Research approach

Evidence and structure are the keys to constructing a convincing and logical argument in support of the idea, insight, contention or recommendation you want to make. In today's business environment it is unlikely that you will be able to find the answer to your question in a single source. You may not find any articles that directly address your question. Therefore, you need to research†¦. And I do not mean being able to use Google Like a good lawyer, you have to bring together a number of different pieces of information.On their own each piece does not mean much but hen you add them all together and YOU explain to the reader how the pieces of Information Interconnect and what the combining of all this Information demonstrates – you are creating a convincing, logical argument. Students often only use the prescribed textbook as the evidence base for their argument. The information within these is generally sound. However, business people do not make decisions based on one source of Information and neither should you.There are a number of search techniques and sources of information that will make the process of generating information easier. If it a completely new topic for you start broad and move to the specific; start with easy to read, general business writing and move to more credible but technical academic writing. If you are a visual learner In the global digital age competition between the worlds best educational institutions is increasing.

Analysis the Crime Pattern of Coastal and Hill Area in Bangladesh

Introduction: Bangladesh lies on the Bay of Bengal. She is also enriched with charming hilly areas. with the advancements of time, crime expands everywhere with its distinctive environmental, geographical & socio-demographical features. The fieldtrip we participated and visited Coast Guard, Chittagong; Cox’s Bazaar & Bandorban district opens us the vital opportunity to acknowledges different patterns of crime in the coastal and hilly regions of Bangladesh. Statement Of The Study:In Bangladesh, the Coast Guard is unique body of force that deals with the crime on the shore of Bay of Bengal and ensure secure sea zone for working & travelling; and also helps to economy on running with smooth velocity through preventing illegal trespassing & outgoing the economic martial’s including manpower. The Cox’s Bazar also a valuable economic zone with its versatility feature of criminal perspectives. The Bandorban is distinct hilly district holds the particular phenomenon†™s of crime.As a student of Criminology and Police Science we have studied the courses of different aspects of crime distributed in different geographical locations but the practical knowledge was unknown to us which are very essential for us. The visit of Coast Guard at Chittagong, Cox’s Bazar and Bandorban helped us greatly in this regard. Background of The Study: Crime is the situational & functional phenomenon that changes from place to place on basis of environment, efficiency of law and order agencies and the socio demographic characteristics of native people.Due to the urbanization and globalization influenced by the different economic factors the modulus of operandi and extent of crime become versatile. The Coast Guard agency at Chittagong region most effetely deals with the costal crime on maintaining law and order in coastal sea area ranges up to 1 km. from the coast. They face the aspects of crime that orientation is totally different on the nature & feature from the crimes crime in land. The Cox’s Bazar is most popular tourist zone with its largest unique sea beach. So it is a valuable open economic zone on road of development.Due to quick urbanization and communicational the socio demographic characteristics of people become trend to be unstable. The Cox’s Bazar is also known as a important corridor of trespassing of criminals and smuggling goods on the land of Bangladesh. The Bandorban is one of the best charming hilly districts in our country. But several geographical characteristics make it distinct from normal people of Bangladesh. At here, keep with the matching with socio demographic feature of people the nature and perspective of crime is totally different from the plane land.On participating as a member in the study tour I’ve acknowledged different patterns of crime with its social & economic consequence in that region. We also informed about the situation and preparation of law and order maintaining agencies, specially the Coast Guard & Police; to meet up these challenges and contributing a role to make Bangladesh better and safer place for working and living. Aims and Objectives: We select some aims to find out through the study- To familiar with the organization of Coast Guard. To acknowledge their role on protecting public & economy, working challenges on sea related crime, glory of achievement etc.To be informed about criminal tread & crime patterns of Cox’s bazaar district. To know about the preparation of Cox’s bazaar police in preventing crime and ensuring safety to the people, especially to the tourist. To familiar with the crime patterns in hilly areas mainly at Bandorban district. To find out entomological reasons of crime in hilly areas. To acknowledge the preparation of police on taking the challenges regarding to meet up these crime. To develop conceptual assessment by analyzing the crime patterns on costal and hilly region. Methodology:It is necessary for the one to know not only the methods but also the methodology. Methodology is a way to systematically solve any problem. Here we all collect data on qualitative process, it is concerned with qualitative phenomenon. Study Area: We visit several placeless on conducting the study tour. We first visit Chittagong coast guard base, then we proceed to Cox’s bazaar & also attended a seminar & a dinar party arranged by district police of Cox’s bazaar. At final stage we visit Bandorban district, there we also took part a discussion with the police authority of district police.Data Collection Method: As it is a qualitative research we used two methods for data collection ? Focus group discussion ?KII and ?Observational method. Findings of the study: The Bangladesh Coast Guard, is unique institution (excluding Armed Forces) fight on the sea for preserving public right and wealth though they have various fundamental deprivation in both personal & administrative context. On Cox’ s bazaar perspective, the native people are gentle & few people commit crime to meet up the demands of urbanization in different way.The crime patterns of costal area treaded to black business related including smuggling, selling drugs. Sometimes we notice some violent patterns of crime including robbery, murder. In Bandorban district, the native hilly people are really peace full. Among them violent crime is rare rather they involved few deviance type of crime. But in Bengali-hilly people mutual perspective there some violent patterns of criminal incidents including robbery, murder, abductions etc. Evolution Of Bangladesh Coast Guard: Prior to the formation of Coast Guard it is Bangladesh Navy who has been entrusted with this sacred policing task at sea.But navy has legal limitation in enforcing customs, fiscal, immigration and other laws at sea. To overcome all these difficulties Coast Guard Act 1994 was passed by parliament in September 1994 and formally the Coast Guard came into being on 22 February 1995. Organizational Organogram of Bangladesh Coast Guard (CG): Organogram of Bangladesh Coast Guard (CG): (Rank) Jurisdiction & Empowerment: Bangladesh Coast Guard has the jurisdiction over the entire sea areas of Bangladesh as declared under the Territorial waters and Maritime Zone Act 1974 and adjacent land areas along the coastal belt up to 1 km.Apart from the sea territory, the government has placed all the waterways of Bangladesh including 1-km land areas from the coasts including the waterways of world’s largest mangrove forest Sundarban. To ensure the task of Bangladesh Coast Guard is empowered to implement rules and regulations under Acts and Ordinances. It have two aspects- National: †¢Bangladesh Coast Guard Act 1994. †¢Immigration Ordinance 1982. †¢Environment Conservation Act 1995. †¢Territorial Waters and Maritime Zones Act 1974. †¢The Marine Fisheries Ordinance 1983. †¢Merchant Shipping Ordinance 1983. †¢T he Customs Act 1969. †¢Narcotics Control Law 1969. Protection and Conservation of Fish Act 1950. †¢The Forest Act 1927. †¢The Port Act 1908 International: †¢United Nations Convention on Law of the Sea III of 1982. †¢Convention for the Prevention of Pollution from Ships, 1973. †¢Convention on Biological Diversity 1992. †¢Convention of Protection of World Culture and Natural Heritage 1972. Under the mentioned Acts and Ordinances the Coast Guard is empowered within the terms of references to arrest any person, seize any property and carryout search having reasons to believe that an offence has been committed in violation of those Acts and Ordinances.Role & function of the Coast Guard: The fundamental role of Coast Guard is to protect the public, the environment, and the national economic and security interests through law enforcement at sea. Role has been clearly defined in the Coast Guard Act 1994 as you can acknowledge: ?Preserve national interests at sea areas of Bangladesh. ?Prevent illegal fishing in sea areas of Bangladesh. ?Prevent unauthorised entry into and illegal exit from Bangladeshi waters. ?Enforce warrant of any court or any other authority against any incoming marine transport or any person onboard that within the territorial waters of Bangladesh. Search and prevent any act of environment pollution in the sea areas of Bangladesh. ?Ensure safety of people working in sea areas of Bangladesh. ?Prevent smuggling and trespassing or narcotics, drugs etc. ?Participate in relief and rescue operations during natural calamities and salvage disastrous water transport, men and materials. ?Arrange transmission of necessary information including warning signals through radio or any other media during natural calamities. ?Assist Bangladesh Navy during war. ?Carry out patrol in Bangladeshi waters. Assist concerned authorities to ensure security of seaports. ?Prevent terrorist and sabotage activities in Bangladeshi waters and ass ist other agencies in this regard. ?Carry out any other duties assigned by the government. Activities of Coast Guard: Coast Guard is involved in many activities. Their participation is in a limited scale but the success rate is praise worthy. Initially the job was limited to anti smuggling and anti piracy operations within port limits of Chittagong and Mongla. But presently they are to operate in the entire coastal belt of the country.They are conducting anti smuggling operations, anti piracy operations, fishery protection operations, catching of illegal arms, forest preservation activities including election duty in the coastal and inland areas. More it successfully conduct some special work on the glory of dignity: Fishery protection operations †¢ Participated in ‘Jatka Nidhon Protirodh Operation’ in the coastal area every year. †¢ Coast Guard received ‘Gold Medal’ in 2005 for outstanding success in Jatka Protirodh operation. Prevention of ferti lizer smuggling :To curb fertilizer smuggling Operation SABUJ DHAN carried out from Sangu, Shah Pori Dwip and Sitakunda.Assistance to Bangladesh Navy (BN): †¢Joint operation is carried out as and when required. †¢CG East Zone tok over inner patrol during Bangladesh Myanmar crisis in 2008. Election duty: †¢Coast Guard was deployed in two constituencies for General Election in 2008 at Dacope and Koira. †¢One contingent were also deployed in Sandwip for Upazilla re-election . Post cyclone relief operation: †¢ Coast Guard carries out post cyclone operation as a regular task whenever required. †¢ Our Ships have contributed by carrying out post cyclone relief operation after the devastating cyclone Sidr in badly affected area like Barishal and Barguna.Special Operations: †¢2006- Operation Nirapad Jiban. †¢20067- Operation Nirapad Upakul. †¢Coast Guard was awarded with ‘Gold Medal’ in 2005 for extra ordinary success in Jatka Protiro dh Operation . †¢In 2006 two ship carried out Joint operation with Indian Coast Guard ship at Haldia, India. †¢In 2009 Coast Guard took part in Ex Somudra Torongo predicated by British Navy ship and Bangladeshi Armed forces and Law Enforcement Agencies Constraints And Limitations of Coast Guard: ?Limited manpower specially shortage of officer. ?No High speed all weather capable ships and boats. The full time security coverage is not possible to the ships beyond outer anchorage. ?No SAR helicopter. Future Plan Of Coast Guard: ?Acquisition of Land. ?Infrastructure and Manpower Development. ?Procurement of Ships / Water craft. Two ships purchasing like CGS RUPOSHI BANGLA is in progress. ?Around 50 high speed boats like US Defender class coming in service very soon ? Air Wing. ?Salvage & Rescue Ships. THE COX’S BAZAR General Orientation of Cox`s bazaar district: Area: 2491. 86 sq. Km Population: 25 Lac. Ratio of Police & citizen is 1 : 3120 No. of Upazila: 8 No. f Union : 71 Annual Rain Fall: 3,378 mm Highest Temp. Avg. :39. 50C (Jun) Lowest Temp. Avg. :11. 80C (Jan) Islands: Moheshkhali, Kutubdia,Matarbari-Dholghata, Sonadia & Saint Martin’s. Main Rivers: Bakkhali, Matamuhuri, Reju,Naf & Kohalia Cox`s bazaar Police District jurisdiction: Circles : Cox’s Bazar (Sadar) Circle Ukhia Circle Police Stations : Cox’sBazar Model Thana Chakoria Thana Moheskhali Thana Kutubdia Thana Ramu Thana Ukhia Thana Teknaf Thana Pekua Thana. Outpost : Town Out Post Beach Out Post Chowfaldody Out Post ( temporary ) Harbang Out Post Badarkhali River Out PostKalarmarchara Out Post ( temporary ) Matarbari Out Post ( temporary ) Rajakhali Out Post ( Temporary ) Garania Out Post Himchari Out Post Eidgoar Out Post St. Martin Out Post Hoyikong Out Post Investigation Centre : ? Eidgoan IC ? Matamuhuri IC ? Baharchara IC CourtSytem of Cox’s bazaar District : ? Sadar Court (Cox’s bazaar model Thana, Ramu Thana, Ukhia Thana and Teknaf Thana ) ? Chakoria Court ? Moheskhali Thana ? Kutubdia Thana Crime Trendsof Cox’s bazaar District (Police Enlisted,2010) This scenario indicates that Narcotics crime (9. 89%),women repression (7. 76%), Smuggling (4. 64%),Theft ( 3. 4%), Illegal Arms offences ( 2. 61%), Murder ( 2. 57%), causing major threat to police. Burglary (1. 91%), Child Repression (1. 75%), Robbery (1. 01%) are causing medium level threat on public safety. Activities of Cox’s Bazaar District Police: ?Organize Community Police Assembly. ?Spontaneous participation on Change himself Change Other self programme. ?Conducting Tourist Policing service 24hours for the safety of tourist at sea beach. ?Arrange Monthly Crime Conference of Cox’s bazaar District Police ? Organize Rally for social consciousness. ?Conducting the programme on beach cleaning initiative Organize Crime Conference and Exchange View ?Organize Police-People Interaction activities e. g . Cricket Match ? Take action against Narcotics ?Acti on to Protect Forest ?Arresting most wanted Criminals ?Action against illegal Myanmar Citizen (Rohinga Issues) †¢Pushback – 442 per. †¢Arrest – 135 per. †¢Case filed – 26 Police Problems of Cox’s Bazaar District: ?Most of the Outposts & Investigation centers have no own land. ?Most of the Outposts & Investigation centers have no permanent & safe structure. ?Insufficient land of new Police line. ?Vacancy of 81 different post of District Police. Vehicle Shortage. ?Ratio of Police & citizen in Cox`sbazar district is 1 : 3120 ? A countable portion of this strength is involve in Refugee camp, BDR Magazine room, VVIP & VIP Protection, KPI`s security. ?No logistic support to prevent Sea Dacoit. ?Residence facility about nil. Analyzing The Crime Patterns In Coastal Area (Coast Guard & Cox’s Bazaar Perspective): On above discussion now we are in the platform to generalize the crime patterns in this two aspects. I proceed on following way- Due to the environmental factors smuggling is the most common crime in this coastal area.Narcotics crime, women repression, Smuggling ,Theft, Illegal Arms offences ,Murder causes threat on police activity, especially on Cox’s Bazaar. Abduction ,Robbery, Dacoit isn’t so frequent criminal feature of crime in this sea level coastal areas. Drug crimes are expanding due to torrent illicit interest for taking drug. Sea (costal) areas are the potential get-way for smuggling, trafficking, illegal Rohinga trespassing etc. Property related conflict / crime is rare to be seen. The ratio between law enforcement personal and public is very poor.So all forms of crime mainly smuggling, criminal & narcotics trespassing, drug crimes, violent crimes is trend to be high day by day. THE HILLY BANDORBAN DISTRICT GENERAL ORIENTATION OF BANDORBAN DISTRICT: ?Bandarban was established as a separate district on 18 April 1981 combining two sub divisions Bandarban and Lama. ?Geographical information : ?This district is surrounded by Myanmar in southern and eastern side. Rangamati in north, Cox’sbazar and Chittagong in western side. ?Area of District : 4,479. 03 Sq. km. †¢Bandarban Sadar : 501. 99 Sq. km. †¢Roangchhari : 442. 89 Sq. km. †¢Ruma: 616. 42Sq. km. †¢Thanchi : 896. 50 Sq. km. Lama: 671. 84 Sq. km. †¢Alikadam: 885. 78 Sq. km. †¢Naikhangchhari : 463. 61 Sq. km ?Demographical information: (As per census 2001) ?Total Population: 3,00,740 ?Male: 1,63,540 ?Female: 1,37,200 ?Tribal : 1,41,213 ?Non Tribal: 1,59,527 ?Population/Sq.. Km:: 67 ?Bangali: 53% ?Tribal: 47% ?Tribal people information: (As per census 2001) In Bandarban 11 indigenous tribes are living with harmony. They are- TribeTotalPopulation †¢Marma75,880 †¢Morong/Mro28,109 †¢Tripura10,478 †¢Tonchonga 7,030 †¢Bom 8,228 †¢Chakma 5,327 †¢Khumi 1,471 †¢Kheyang 1,823 †¢Chak 2,151 †¢Pankhu 128 †¢Losai 293 ?Administrative Units in formation: Police Circles : 02 †¢Sadar Circle: Bandarban, Ruma, Roangchori, Thanchi. †¢Lama Circle:Lama, Alikadam, Naikhongchari. ?Upazilla: 07 ?Union : 29 ?Municipality: 02 ?Police Station: 07 ?Police Investigation Center: 02 ?Police Outpost: 07 ?Police Camp: 11 ?Region(Army): 01 ?Zone(Army): 03 (Sadar,Ruma, Alikadam) ?Zone(BDR): 02 (Balipara, N. chhari) ?Ansar Battalion : 01 ?Cultural Festival information: ?Rajpunna ( Rajpunna is one kind of fair. Where the king of Bomang circle collect tax from the â€Å"Headman and the Karbari’’, Headman and Karbari collect the tax from their local area. Headman and Karbari selected by Bomang circle king. ` Rajpunna’’ fair commences once a year. ) ? Buddo Purnima ?Baisabi, (Sangrai- Marma, Biju- chakma) ?Cow Killing of Murung ?Political information:(Political parties) ?Awami league ?BNP ?Jammat ?Jatiyo Party ?UPDF (United Peoples Democratic Front. Founded on 26 December 1998. The UPDF is a Manifestation of the strong and serious reservations against the Chittagong Hill tract Accord 2 December 1997. ?PCJSS (Parbatya Chittagram Jana Samhati Samiti. Founded on 24 April 1972 by Manabendra Narayan Larma. Present Presedent Sri Jotindro Bodhy Prio Larma Law and Order Situation Of Bandorban District: The Police Force has sufficient manpower and well equipped with modern arms and ammunitions to keep daily law and order situation under control. ? The Police usually gets cooperation from local Army and BDR to secure arrest of miscreants from the remote hilly areas. ? There are rare incidents of breach of peace and amity between local tribes and Bangalis. Crime Statistics: Of Bandorban District (2005- 2009) Analyzing the Crime Trend Of Bandorban District: ?Despite its landscape, propensity of crime is much less than plain land. ?The tribal populated area is less crime prone than Bangali populated area here. There is hardly any case filed in Thanchi, Ruma and Roangchhari police stations. ?Bangali populated areas like Sadar, Lama, Naikkhongchhari, Alikadam are much crime prone. ?Tribal people commit mostly Alcohol related crimes. ?Property related crimes like Theft, Dacoity etc are less committed here. ?Few incidents of murder occur in remote hilly areas. ?The Crime Statistics indicates that theft & murder causes high risks on public safety. Major focus: ?Kidnapping /Abduction ?Extortion ?Land Dispute ?Conflict between tribe and non tribe ?Illegal entry of foreigners ?Rohinga issue. Special Type of Crime: Though evil activities of so called ‘Shanti Bahini’ is not evident, few terrorists create panic through abducting people. ? Terrorists kidnap such persons for ransom and hide themselves in remote hilly forest. ?Considering the safety of abducted persons the relatives avoid law enforcing agencies and conceal fact. They try to free the abducted by paying the ransom. District Police Efficiency in Crime Combating: ?Ensuring quality of investigation ?Effective court procedure management ?Pro-active approach of policing ?Applying appropriate preventive sections of laws like 151 of Crpc and 107 and 117 ©. Community policing; In Response to — ?Domestic Violence ?Trafficking ?Eve-teasing awareness ?Dowry ?Traffic education ?Drug abuse ?School visit for ensuring education and health care ?Tree plantation ?Preserving forest ?Community awareness ?Fire management ?Preservation of hill. Comparison of the crime pattern of coastal and hill area through Analysis : On the base of critical assessment of coastal (Chittagong & Cox’s Bazaar) and Hilly area (Bandorban) now we note as follows- The crime trend on hilly areas is lower than coastal area. Most prominent crime in coastal areas is smuggling.On the other hand, at hilly area we found abduction & murder are the most affected Crime. The hilly people commit pretty alcohol related crime, sometimes we see property conflict between hilly people & Bengali People but this feature is absent at Cox ’s Bazaar. Roninga issue is common problem in both Cox’s Bazaar and Bandorban. Due to the communication obstacle law enforcement personal have serve more hardship in Bandorban than Cox’s Bazaar. There’s no existence of crime committed by â€Å"Santi Bahini† at Cox’s Bazaar but the criminal activities are done in the name of this â€Å"Santi Bahini† at Bandorban.Overall, Hilly people are more peaceful than Bengali people of coastal area. Limitations Of The Study: Though the visit in these coastal & hilly areas helped us very much to gain empirical and practical knowledge in the field of investigation but to visit it we have faced some problems . The main limitation were- ? We didn’t get enough time on staying for collecting data at a one place. ?We collect all these information from representative administrative side, we’ve no scope to verify our findings at field level. Sometimes police representative personal seems like pay unwillingness in answering some fundamental issues. Conclusion: On visiting both these region we become enriched with the knowledge’s that we didn’t have before. This empirical and practical knowledge’s helps us to analyzes the distinct patterns of crime aspects in academic studies. Bibliography Digital documents material, provide by- ?Coast Guard Authority, Chittagong. ?Cox’s Bazaar Police authority ?Bandorban Police Administration Related internet services.

Bruno Bettleheim’s “The Use of Enchantment”

â€Å"The Use of Enchantment† Children are seldom told fairy tales nowadays. There are several story books for children with moral lessons to learn at the end of the book. There are many great kids books with standards of moral values, which are favorite for family education. With many books to choose from, children have astounding choices of reading materials. Together with classics, there are classic story books with the adventures of licensed characters, irony, and new story books with every possible topic.These books entertain children and teach them at the same time. Some books include brief history and science lessons. Other features of these books include dinosaurs and other animals. Some few books emphasize on the societal values and virtues like sincerity and honor. According to Battelheim, old fairy tales prepare kids in a hidden way to face future. Even though the children's subconcious does not desire to be interrogated, their conscious minds are willing to share w hat they learned from several fairy tales.For example, a book like ‘Red Riding Hood' teaches children to follow shortcuts through the forest. A book like â€Å"The Three Little Pigs† teaches hildren how they can live in brick houses in order to protect themselves from enemies. It helps children develop defensive mechanisms against harmful animals and other things. Other books like â€Å"Goldilocks† teach children that there is nothing, which is ever right. It educates children on the importance of acknowledging mistakes and correct them.In his book â€Å"The Uses of Enactment† Bruno wrote a lot about mental illness in children, and autism among other issues. Even though his views were highly held by lots of people, many people have now discredited Bruno's views. Many of Bettelheim's claims and credentials are now under scrutiny from both supporters and detractors. He applied the theory of Freudian on fairy tales for children. Bettelheim used the theory as the basis to explain the significance of symbolic and emotional messages to children.The author believed that when children read conventional fairy tales, they develop and mature emotionally. For those who tend to avoid the theory of Freudian, â€Å"The Uses of Enactment† is suitable for the translation of old stories. Some of the stories may instill fear in children's developing minds. Bettelheim's book not only examines imageries within the hildren's story books, but also compares them to other conventional symbols such as religious images and other storytelling styles.The Freudian theory is used in Bruno's book to provide n motivating enlightenment of the functions of old stories in the development of children. For example, in the book â€Å"Little Red Riding Hood† the theme of transformation helps in illustrating fears and concerns among children. Together with the classic versions of kids' stories assessed, Bettelheim exams several variations of stories. He compar es and contrasts differences in various stories with their symbols. On the other hand, those who do not concur with Freudian theory will find several unanswered questions from â€Å"The Uses of Enactment. Generally, analyses by Bettelheim Bruno is essential in examining the importance of fairy tales to children's owtn These books expose kids to ditterent contexts, cultures, and themes. They also expose children to different character traits. These attributes are essential for the children's physical and psychological growth. The books teach the children to be creative and apply some of the books' attribute in while playing. They tend to imitate the characters in those story books while playing.

Analysis of two learning environment designs Essay

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Eukaryotic and Prokaryotic cells - Essay Example DNA as we know tells us about our family structure and passes on from one generation to another. The large number of cells and their network helps in differentiating the DNA structure. The DNA keeps of replicating with the help of template polymerization. The Eukaryotic and Prokaryotic cells are made up of similar basic chemicals like carbohydrates, proteins, nucleic acid, minerals, fats and vitamins, while making use of proteins as catalysts. The hereditary information is transformed into RNA, which in turn is translated into proteins. Therefore these two cells are similar in nature in many respects. But, there are a number of features which differentiate these two types cells from each other. One of the major distinctive feature is that the Prokaryote is without a nucleus, therefore the DNA keeps floating around in an unorganized manner in the cells. But on the other hand, the Eukaryote cells have a large centrally located nucleus, surrounded by double layer of membrane known as nuclear envelope. This envelope contains nucleoplasm. The DNA is held within this nucleus only. The nucleus being the centre of activities is also termed as brain of the cell. Prokaryotic cells do not have the organelles, but Eukaryotic cells have organelles which allow them to perform more complex functions. Both these cells differ in respect of their size as well.

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Paraphrase - Essay Example This extends sources of the practitioners’ knowledge to available historical data through existing publications (Hoffmann, Bennett and De Mar, 2010; Akobeng, 2005). Systematic review is also important to knowledge development for new research. Its analytical approach that plays the same role as formal literature review allows researchers to consolidate existing knowledge on a subject and to identify knowledge gaps for possible new studies. The reviews, with this respect, contribute to new research through informing research objectives, research questions, and research hypotheses. In addition, results of systematic reviews identify theories from related research that can be used in proposed or future studies. Effects of the reviews also extend to influence on research methodologies of new studies through elements such as selection of research methods and design, sampling strategy, and data collection strategy and tools. Ability of systematic reviews to identify weaknesses of pr evious studies also offer a basis for corrective measures and therefore helps to resolve such problems like bias in studies (Booth, Rees and Beecroft, 2010). Data extraction is a process by which data is collected from their sources and is organized into desired form for presentation to the audience. Examples of forms in which extracted data can be communicated are tables and graphs that facilitate understanding. Data extraction is a fundamental process in systematic reviews and helps in identification of elements of a research such as a study’s methods and design, sample and population, and applied treatment and mode of application. The process of data extraction is however largely subjective to a researcher’s interest and opinion and therefore susceptible to bias (Cochrane Handbook, 2011; Petticrew & Roberts, 2006). Summary of studies’ findings is important to any form of analysis and

Four Freedoms for All Essay Example | Topics and Well Written Essays - 1500 words

Four Freedoms for All - Essay Example The first freedom, that of speech is the hallmark of a democratic society where people are free to express their opinions on a variety of subjects. Speech differentiates man from any other form of life and allows humans to communicate, and through this communication to explore and create in fields as diverse as music or art, science or medicine. This freedom of speech and expression is not just a basic right, but also a means to impart ideas that contribute to man’s ever increasing knowledge as well as his growth, happiness, and well-being. The curtailment of this freedom can subdue man for a while but in the end, when he sees others enjoying it, revolt is inevitable. In today’s world of speedy communication, this phenomenon is being increasingly seen in the overthrow of dictatorships around the world. In democratic societies, it is the tool used to keep a watch on the activities of those in power, because unbridled power can lead to corruption. This freedom in the hand s of the media is a powerful tool to place facts before the people so they are in a position to make informed choices while choosing their leaders. However, every right comes with a responsibility and freedom of speech does not mean maligning others or their way of life and customs or traditions. A responsible way to use freedom of speech is to respect the rights and freedoms of others. The second freedom is man’s freedom to worship the god or gods of his choice and in a way, he feels fit for his own peace of mind. Today religious intolerance is what is leading to many of the world’s problems. ... It is important to note that a man’s religion or religious beliefs are his personal choice hence it is important for each one of us to have the freedom to choose whom we worship and how we do it. Ultimately all religions preach the same things and they really are the same except for the names that they go by, which again are given to them by man. Religion and religious beliefs have always been the source of conflict since the time man began to worship nature and the elements. Every religion has gone through phases when people were killed and tortured in the name of religion. Most religious leaders are under the impression that the greater the numbers of their followers, the better their religion or the stronger their faith, little realizing that no religious body teaches its followers to kill or steal or lie. Despite this underlying truth that is self evident, religious persecutions have dogged mankind from time immemorial and persist even to this day. International bodies can pass resolutions and nation states can pass laws, but ultimately unless man is willing to admit that religion is a personal choice and cannot be forced on another through fear, real freedom of worship cannot be attained. The third freedom, that of freedom from want is the vast imbalance between the haves and the have nots. There are some countries in our world where poverty is rampant. The people do not have the basic necessities of two square meals a day or a roof over their heads. Here malnourished mothers give birth to underweight babies who do not have a chance to grow into healthy children or adults. Infant mortality rates are high, and those babies who do survive, fall prey to diseases that are spread due to the unhygienic conditions in

Legal and Ethical Considerations in Marketing, Product Safety, and Essay - 1

Legal and Ethical Considerations in Marketing, Product Safety, and Intellectual Property - Essay Example Correspondingly, recommendations have also been provided in the essay so as to mitigate the identified challenges. Ethical issues relating to marketing and advertising, intellectual property, and regulation of product safety Use of negative advertisement techniques The use of negative techniques refers to the adoption of comparative advertisement strategy by the companies. In this unethical practice, the advertisement focuses on the disadvantages of the competitor’s product. Arguably, in the modern phenomenon, this technique has become a major tool for promoting the utility of the products of a particular company (Majtan & Dubcova, n.d.). Misleading or dishonest advertisement It is one of the most serious ethical problems that have been observed as commonly used by many of the advertisers in the modern day. It involves not only misleading facts about the product but also false impression forecasted. Any advertiser who fails to promote the truth of the product not only goes aga inst morality but also against the law as it violates customer protection rights to information. The advertisement must also not include any kind of false statement regarding the product or claim for the dishonest value of that product (Majtan & Dubcova, n.d.). Copyright infringement It is one of the most serious unethical issues that are observed in the field of intellectual property. Notably, the copyright infringement occurs whenever a person who does not own the copyright violates any of the rights of others without permission. The most common practice found in this aspect is breach of reproduction right and invention of new work base under the existing one (Tehranian, 2007). Use of unsafe raw materials in the production Many of the companies use cheap quality material in the production of its final product for the sake of earning maximum profits. They do not keep consumer health or stakeholders’ interest into consideration being highly concerned about the profitability o f their company. For example, in a free market, if a health drink manufacturing company uses cheap quality ingredients in production, it would ultimately affect the health of the consumers offering the company with profits, but only for a limited period in the short-run, inhibiting the company’s sustainability interests to a substantial extent (Dufferin-Peel Catholic District School Board, 2013). Argue for Direct-to-Consumer (DTC) marketing by drug companies The sponsorship of pharmaceutical drugs through Direct-to-Consumer (DTC) has much significance in the current market scenario as it promotes customer confidence and provides better opportunity to the company to align the marketing strategies with customer preferences to a greater extent. In the US, majority of the drug companies have been found spending double than the total amount in DTC marketing technique (Mogull, 2008). On the contrary, there exist many customers who are strictly against this technique of advertising on grounds that because the technique requires substantial financial investments, the drug companies focusing on direct-to-customers selling concept have to spent maximum money on advertising rather than on research and development. However, considering its positive effects, the Food and Drug Administration (FDA)

PROBLEMS WITH THE PAROLE AND PROBATION SYSTEM IN THE UNITED STATES Research Paper

PROBLEMS WITH THE PAROLE AND PROBATION SYSTEM IN THE UNITED STATES - Research Paper Example This specific problem is one which can be attributed to the system with the probation programs because of the inability to meet the needs of those that are adjusting back into society. Problem within Probation Programs The criminal offender conduct is the main concept that is focused on with probation programs. Those who are working with criminals who have just been released from prison are focused on changing mannerisms and ensuring that the prisoner is able to work within society as a citizen. Getting steady employment, staying away from further crime and developing new habits within society are some of the associated concepts that are a part of probation programs. Supervising those individuals and working with counseling programs are also some of the attributes that are a part of probation programs. However, there is a noticeable re-entry crisis that occurs among criminals. The inability to change the focus out of the habits from past crimes and the inability to provide criminals with the ability to move into a completely correctional system are causing many criminals to go through probation periods then move back into the same crimes as in the past (Johnson et al, 2006). The problem with those who are in parole systems is one which is showing a high return rate that is not decreasing with the systems that are in place. In 2006, an average of 35% of all inmates returned to prison during or after the probation period. This was a result of parole violations, as opposed to new crimes that were committed. The state of California held the highest of parole violations, which was inclusive of two-thirds of inmates returning to prison because of the same violations. The problems with probation include the first problem of too many inmates being supervised with too little supervision. In 2006, 4 million offenders were placed into probation. The officers were primarily responsible for the movement back into society with other court orders that were associated with thi s. It was found that the restrictions with probation, such as not being able to find employment because of a criminal record, led to many being forced into breaking the probation rules to try to integrate into society (Lawrence, 2008). The parole systems, while known to assist with the integration back into society, are causing the reverse problem to occur. Those who are within the system and are going through parole are aware that there is difficulty in getting past probation systems and staying in society. There are many who have created the mentality that they will go back into prison during their probation period, adding in a psychological response to the known statistics and rates of those who are going in and out of the justice system. Those who are going back into prison work as an example of the difficulties within the probation and parole system, making the trend arise among those who are a part of the probation system and which are trying to work back into an integrated so ciety. The psychological responses, trends and the large amount of criminals that go back into prison add into the complexity of those who are going through the parole system (Johnson et al, 2006). Theories of Criminal Justice Practice There are several theories that apply to the criminal justice practice and the way in which individuals integrate into society. Historically, those who had committed a crime were only required to serve

Annotated Review of Literature Essay Example for Free

Annotated Review of Literature Essay Annotated Review of Literature to Support how Differentiated Instruction Workshops can Improve Instruction Hawkins, V. (2009). Barriers to implementing differentiation: Lack of confidence, efficacy and perseverance. The New England Reading Association Journal, 44(2), 11-16. Retrieved from Education Full Text database. Annotation: In this article, Hawkins exposes three major reasons why implementing differentiated instruction (DI) if a difficult task for most teachers. Hawkins states that districts advocate for professional development of DI as a reactive response to current data trends in education. The goal of this article is to provide classroom teachers with the necessary skills to be able to implement DI into their curriculum. The researcher found that a lack of teacher confidence, lack of teacher efficacy, and a lack of perseverance are three factors in which teachers most often struggle with when trying to differentiate lessons. Support for Project: This article gives important information for teachers on how to overcome the barriers of implementing effective DI into their curriculum. So many of us face the same problems when trying to differentiate our lessons, therefore, it is important for teachers to understand how to overcome these barriers and also to understand that they are not alone in this daunting task. Hawkins goes on to describe each barrier in detail to help teachers overcome them so they can become effective DI instructors. Tomlinson, Carol Ann. Carol Ann Tomlinson explains how differentiated instruction works and why we need it now. Making A Difference, September 2007. Annotation: In this article, Carol Ann Tomlinson, who is a leader in the field of education on Differentiated Instruction, explains what DI is, why it is so important in education today, as well as in the future, and the characteristics of an effective differentiated classroom. Tomlinson also reviews some key points that teachers need to think about when developing a differentiated lesson plan. The researcher goes on to explain that the reason DI is so important is that students vary in so many ways, and our student populations are becoming more and more academically diverse. Support for Project: This article is important for my project because the researcher explains how to deal with student differences. Today’s classrooms are so diverse and teachers need to know how to deal with these differences on a daily basis. Tomlinson states that there are three ways to deal with differences: ignore them, separate or â€Å"track† them, or keep students together in the context of high-quality curriculum (differentiated instruction). Obviously the third one should be the way to go, but unfortunately, it is the road least traveled. This article also describes the characteristics of a well-run DI classroom and what teachers need to do in order to be successful when creating differentiated lessons to improve instruction. Tomlinson, C. (2005). Traveling the road to differentiation in staff development. Journal of Staff Development, 26(4), 8-12. Retrieved from Education Full Text database. Annotation: In this article, Tomlinson explains how teacher leaders can help educators hurdle four key barriers teachers face when trying to implement DI into their classrooms. The researcher describes the need for DI in the United States education system and also reviews six strategies of effective differentiation. Tomlinson goes over current research findings about student achievement and differentiation in response to readiness, interest, and learning profiles. Support for Project: This article is important for my project because when trying to convince educators to change their way of thinking and pedagogical practices, you must have solid evidence that the new practice; in this case, DI, will work. This article goes over the latest research findings to support DI and it also gives effective strategies for implementing DI practices as well as ways to overcome barriers of incorporating DI into the curriculum. The goal of my project is to design a workshop to inform educators about differentiated instruction; what it is, why we need it, what effective DI practices look like, what the keys aspects of DI are, how to overcome the barriers of DI, and what the current research of DI is. This article does a good job of reviewing these topics. Wormeli, R. (2007). Differentiation: From planning to practice grades 6-12. Portland, ME: Stenhouse. Annotation: In this book, Wormeli provides a practical way for teachers to create a differentiated lesson from start to finish. He walks educators through the lesson, giving details on what steps to take before, during, and after to make deep connections for students. He gives effective strategies and advice on how to reach â€Å"all† learners within one classroom. Wormeli presents models of effective differentiated instruction, so that teachers can extend what they learn to any subject and any classroom. Support for Project: When creating a workshop for educators on differentiation, it is important to include models of instruction for teachers to reflect upon and use as examples for the future. That is just what this book does. Wormeli gives annotated models of effective differentiated instruction, such as tiering, flexible grouping, how to make adjustments based on formative assessments, and interdisciplinary examples for teachers to learn how to do. Once educators feel comfortable using these strategies, they can extend these procedures throughout their careers.

Modelling of Meromorphic Retina

Modelling of Meromorphic Retina CHAPTER 1 INTRODUCTION and literature review 1. INTRODUCTION The world depends on how we sense it; perceive it and how we act is according to our perception of this world. But where from this perception comes? Leaving the psychological part, we perceive by what we sense and act by what we perceive. The senses in humans and other animals are the faculties by which outside information is received for evaluation and response. Thus the actions of humans depend on what they sense. Aristotle divided the senses into five, namely: Hearing, Sight, Smell, Taste and Touch. These have continued to be regarded as the classical five senses, although scientists have determined the existence of as many as 15 additional senses. Sense organs buried deep in the tissues of muscles, tendons, and joints, for example, give rise to sensations of weight, position of the body, and amount of bending of the various joints; these organs are called proprioceptors. Within the semicircular canal of the ear is the organ of equilibrium, concerned with the sense of balance. General senses, which produce information concerning bodily needs (hunger, thirst, fatigue, and pain), are also recognized. But the foundation of all these is still the list of five that was given by Aristotle. Our world is a visual world. Visual perception is by far the most important sensory process by which we gather and extract information from our environment. Vision is the ability to see the features of objects we look at, such as color, shape, size, details, depth, and contrast. Vision is achieved when the eyes and brain work together to form pictures of the world around us. Vision begins with light rays bouncing off the surface of objects. Light reflected from objects in our world forms a very rich source of information and data. The light reflected has a short wavelength and high transmission speed that allow us a spatially accurate and fast localization of reflecting surfaces. The spectral variations in wavelength and intensity in the reflected light resemble the physical properties of object surfaces, and provide means to recognize them. The sources that light our world are usually inhomogeneous. The sun, our natural light source, for example, is in good approximation a point sou rce. Inhomogeneous light sources cause shadows and reflections that are highly correlated with the shape of objects. Thus, knowledge of the spatial position and extent of the light source enables further extraction of information about our environment. Our world is also a world of motion. We and most other animals are moving creatures. We navigate successfully through a dynamic environment, and we use predominantly visual information to do so. A sense of motion is crucial for the perception of our own motion in relation to other moving and static objects in the environment. We must predict accurately the relative dynamics of objects in the environment in order to plan appropriate actions. Take for example the following situation that illustrates the nature of such a perceptual task: the batsman a cricket team is facing a bowler. In order to get the boundary on the ball, he needs an accurate estimate of the real motion trajectory of the ball such that he can precisely plan and orchestrate his body movements to hit the ball. There is little more than just visual information available to him in order to solve the task. And once he is in motion the situation becomes much more complicated because visual motion information now represents the relative motion between him and the ball while the important coordinate frame remains static. Yet, despite its difficulty, with appropriate training some of us become astonishingly good at performing this task. High performance is important because we live in a highly competitive world. The survival of the fittest applies to us as to any other living organism, although the fields of competition might have slightly shifted and diverted during recent evolutionary trends. This competitive pressure not only promotes a visual motion perception system that can determine quickly what is moving where, in which direction, and at what speed; but it also forces this system to be efficient. Efficiency is crucial in biological systems. It encourages solutions that consume the smallest amount of resources of time, substrate, and energy. The requirement for efficiency is advantageous because it drives the system to be quicker, to go further, to last longer, and to have more resources left to solve and perform other tasks at the same time. Thus, being the complex sensory-motor system as the batsman is, he cannot dedicate all of the resources available to solve a single task. Compared to human perceptual abilities, nature provides us with even more astonishing examples of efficient visual motion perception. Consider the various flying insects that navigate by visual perception. They weigh only fractions of grams, yet they are able to navigate successfully at high speeds through complicated environments in which they must resolve visual motions up to 2000 deg/s. 1.1 ARTIFICIAL SYSTEMS What applies to biological systems applies also to a large extent to any artificial autonomous system that behaves freely in a real-world environment. When humankind started to build artificial autonomous systems, it was commonly accepted that such systems would become part of our everyday life by the year 2001. Numberless science-fiction stories and movies have encouraged visions of how such agents should behave and interfere with human society. And many of these scenarios seem realistic and desirable. Briefly, we have a rather good sense of what these agents should be capable of. But the construction is still eluding. The semi- autonomous rover of NASAs recent Mars missions or demonstrations of artificial pets are the few examples. Remarkably the progress in this field is slow than the other fields of electronics. Unlike transistor technology in which explosion of density is defined by the Moores law and also in terms of the computational powers the performance of autonomous systems is still not to the par. To find out the reason behind it we have to understand the limitation of traditional approaches. The autonomous system is the one that perceives, takes decision and plans action at a cognitive level, in doing so it must show some degree of intelligence. Returning back to the batsman example, he knows exactly what he has to do to dispatch the ball to the boundary, he has to get into a right position and then hit the ball with a precise timing. In this process, the photons hit the retina and then muscle force is applied. The batsman is not aware that this much is going on into his body. The batsman has a nervous system, and one of its many functions is to instantiate a transformation layerbetween the environme nt and his cognitive mind. The brain reduces and preprocesses the huge amount of noisy sensory data, categorizes and extracts the relevant information, and translates it into a form that is accessible to cognitive reasoning. Thus it is clear here that the there is cluster of process that takes place in a biological cognitive system in a very short time duration. And also that an important part of this whole process is transduction although it is not the one that can solely perform the whole complex task. Thus perception is the interpretationof sensory information with respect to the perceptual goal. The process is shown in the fig-1. 1.2 DIFFERENCE BETWEEN BIOLOGICAL SYSTEMS AND COMPUTERS The brain is fundamentally differently organized than a computer and science is still a long way from understanding how the whole thing works. A computer is really easy to understand by comparison. Features (or organization principles) that clearly distinguish a brain from a computer are: Massive parallelism, Distributed storage, Asynchronous processing, and Self organization. The computer is still a basically serially driven machine with a centralized storage and minimal self organization. The table 1.1 enlists these differences. Table 1.1 Differences in the organization principles and operation of computer and brain The digital computation may become so fast that it may solve the present problems and also it may become possible that the autonomous systems are made by digital components that are as powerful as efficient and as intelligent as we may imagine in our wildest dreams. However there are doubts in it and so we have to switch to an implementation framework that can realize all these things. 1.3 NEURAL COMPUTATIONS WITH THE HELP OF ANALOG INTEGRATED CIRCUITS It was Carver Mead who, inspired by the course â€Å"The Physics of Computation† he jointly taught with John Hopfield and Richard Feynman at Caltech in 1982, first proposed the idea of embodying neural computation in silicon analog very large-scale integrated (aVLSI) circuits. Biological neural networks are examples of wonderfully engineered and efficient computational systems. When researchers first began to develop mathematical models for how nervous systems actually compute and process information, they very soon realized that one of the main reasons for the impressive computational power and efficiency of neural networks is the collective computation that takes place among their highly connected neurons. And in researches, it is also well established that these computations are not undertaken digitally although the digital way is much simpler. Real neurons have a cell membrane with a capacitance that acts as a low-pass filter to the incoming signal through its dendrites; they have dendritic trees that non-linearly add signals from other neurons, and so forth. Network structure and analog processing seem to be two key properties of nervous systems providing them with efficiency and computational power, but nonetheless two properties that digital compute rs typically do not share or exploit. 1.4 LITERATURE REVIEW 1. Biological information-processing systems operate on completely different principles from those with which most engineers are familiar. For many problems, particularly those in which the input data are ill-conditioned and the computation can be specified in a relative manner, biological solutions are many orders of magnitude more effective than those we have been able to implement using digital methods. This advantage can be attributed principally to the use of elementary physical phenomena as computational primitives, and to the representation of information by the relative values of analog signals, rather than by the absolute values of digital signals. This approach requires adaptive techniques to mitigate the effects of component differences. This kind of adaptation leads naturally to systems that learn about their environment. Large-scale adaptive analog systems are more robust to component degradation and failure than are more conventional systems, and they use far less power . For this reason, adaptive analog technology can be expected to utilize the full potential of wafer scale silicon fabrication 2. The architecture and realization of microelectronic components for a retina-implant system that will provide visual sensations to patients suffering from photoreceptor degeneration. Special circuitry has been developed for a fast single-chip CMOS image sensor system, which provides high dynamic range of more than seven decades (without any electronic or mechanical shutter) corresponding to the performance of the human eye. This image sensor system is directly coupled to a digital filter and a signal processor that compute the so-called receptive-field function for generation of the stimulation data. These external components are wireless, linked to an implanted flexible silicon multielectrode stimulator, which generates electrical signals for electro stimulation of the intact ganglion cells. All components, including additional hardware for digital signal processing and wireless data and power transmission, have been fabricated using in-house standard CMOS technology 3. The circuits inspired by the nervous system that either help verifying neuron physiological models, or that are useful components in artificial perception/action systems. Research also aims at using them in implants. These circuits are computational devices and intelligent sensors that are very differently organized than digital processors. Their storage and processing capacity is distributed. They are asynchronous and use no clock signal. They are often purely analog and operate time continuous. They are adaptive or can even learn on a basic level instead of being programmed. A short introduction into the area of brain research is also included in the course. The students will learn to exploit mechanisms employed by the nervous system for compact energy efficient analog integrated circuits. They will get insight into a multidisciplinary research area. The students will learn to analyze analog CMOS circuits and acquire basic knowledge in brain research methods. 4. Smart vision systems will be an inevitable component of future intelligent systems. Conventional vision systems, based on the system level integration (or even chip level integration) of an image (usually a CCD) camera and a digital processor, do not have the potential for application in general purpose consumer electronic products. This is simply due to the cost, size, and complexity of these systems. Because of these factors conventional vision systems have mainly been limited to specific industrial and military applications. Vision chips, which include both the photo sensors and parallel processing elements (analog or digital), have been under research for more than a decade and illustrate promising capabilities. 5. Dr. Carver Mead, professor emeritus of California Institute of Technology (Caltech), Pasadena pioneered this field. He reasoned that biological evolutionary trends over millions of years have produced organisms that engineers can study to develop better artificial systems. By giving senses and sensory-based behavior to machines, these systems can possibly compete with human senses and brings an intersection between biology, computer science and electrical engineering. Analog circuits, electrical circuits operated with continuous varying signals, are used to implement these algorithmic processes with transistors operated in the sub-threshold or weak inversion region (a region of operation in which transistors are designed to conduct current though the gate voltage is slightly lower than the minimum voltage, called threshold voltage, required for normal conduction to take place) where they exhibit exponential current voltage characteristics and low currents. This circuit paradigm pr oduces high density and low power implementations of some functions that are computationally intensive when compared with other paradigms (triode and saturation operational regions). {A triode region is operating transistor with gate voltage above the threshold voltage but with the drain-source voltage lower than the difference between the gate-source voltage and threshold voltage. For saturation region, the gate voltage is still above the threshold voltage but with the drain-source voltage above the difference between the gate-source voltage and threshold voltage. Transistor has four terminals: drain, gate, source and bulk. Current flows between the drain and the source when enough voltage is applied through the gate that enables conduction. The bulk is the body of the transistor.}. As the systems mature, human parts replacements would become a major application area of the Neuromorphic electronics. The fundamental principle is by observing how biological systems perform these func tions robust artificial systems are designed. 6. In This proposed work a circuit level model of Neuromorphic Retina, this is a crude electronic model of biologically inspired smart visual sensors. These visual sensors have integrated image acquisition and parallel processing. Having these features neuromorphic retina mimics the neural circuitry of bionic eye. The proposed electronic model contains adaptive photoreceptors as light sensors and other circuit components such as averaging circuits, circuits representing ganglion cells, neuronal firing circuits etc that junction to sense brightness, size, orientation and shape to distinguish objects in closer proximity. Although image-processing features are available with modern robots but most of the issues related to image processing are taken care by software resources. Whereas machine vision with the help of neuromorphic retina is empowered with image processing at the front end. With added hardware resources, processing at the front end can reduce a lot of engineering resources for making electronic devices with sense of vision. 1.5 OBJECTIVES OF THE PRESENT WORK This project work describes a circuit level model of Neuromorphic Retina, which is a crude electronic model of biologically inspired smart visual sensors. These visual sensors have integrated image acquisition and parallel processing. Having these features neuromorphic retina mimics the neural circuitry of bionic eye. The proposed electronic model contains adaptive photoreceptors as light sensors and other neural firing circuits etc at junction to sense brightness, size, orientation and shape to distinguish objects in closer proximity. Although, image processing features are available with modern robots but most of the issues related to image processing are taken care by software resources. Whereas, machine vision with the help of neuromorphic retina is empowered with image processing at the front end. In this paper it has been shown that with added hardware resources, processing at the front end it can reduce a lot of engineering resources as well as time for making electronic devic es with sense of vision. . The objectives of present work are: Modelling of Neuromorphic Retina The photoreceptor block The horrizontal cell block The transistor mesh implemented with cmos technology The integerated block The integrated block of prs, horizontal cells and bipolar cells The spike generation circuit 1.6 Concluding Remarks In this chapter, the function of the artificial system, difference between brain and computer work is described. The present work is focused on designing of neuromorphic retina layer circuits. Many successful studies have been carried out by the researchers to study the behavior and failure of neuromorphic retina. Some investigators have performed the experimental work to study the phenomenon of the neuromorphic retina. Chapter 2 conations the biological neurons and the electronics of neuromorphic retina in this the descriptions of silicon neurons, electrical nodes as neurons, perceptrons, integrate fire neurons, biological significance of neuromorphic systems, neuromorphic electronics engineering methods, process of developing a neuromorphic chip. Chapter 3 describes the artificial silicon retina, physiology of vision, the retina, photon to electrons, why we require the neuromorphic retina?, the equivalent electronic structure, visual path to brain. In chapter 4 designing and implementation of neuromorphic retina in this the description of the photoreceptor block, the horrizontal cell block, the integerated block, the integrated block of photoreceptors, horizontal cells and bipolar cells, the spike generation circuit. In chapter 5 the design analyses and test results of neuromorphic retina layers. The results are summarized in the form of conclusion in Chapter 6 CHAPTER-2 BIOLOGICAL neurons AND neuromorphic electronics 2.1 INTRODUCTION Neuromorphic systems are inspired by the structure, function and plasticity of biological nervous systems. They are artificial neural systems that mimic algorithmic behavior of the biological animal systems through efficient adaptive and intelligent control techniques. They are designed to adapt, learn from their environments, and make decisions like biological systems and not to perform better than them. There are no efforts to eliminate deficiencies inherent in biological systems. This field, called Neuromorphic engineering, is evolving a new era in computing with a great promise for future medicine, healthcare delivery and industry. It relies on plenty of experiences which nature offers to develop functional, reliable and effective artificial systems. Neuromorphic computational circuits, designed to mimic biological neurons, are primitives based on the optical and electronic properties of semiconductor materials 2.1 BIOLOGICAL NEURONS Biological neurons have a fairly simple large-scale structure, although their operation and small-scale structure is immensely complex. Neurons have three main parts: a central cell body, called the soma, and two different types of branched, treelike structures that extend from the soma, called dendrites and axons. Information from other neurons, in the form of electrical impulses, enters the dendrites at connection points called synapses. The information flows from the dendrites to the soma, where it is processed. The output signal, a train of impulses, is then sent down the axon to the synapses of other neurons. The dendrites send impulses to the soma while the axon sends impulses away from the soma. Functionally, there are three different types of neurons: Sensory neurons They carry information from sense receptors (nerves that help us see, smell, hear taste and feel) to the central nervous system which includes the brain and the spinal cord. Motor neurons They carry information from the CNS to effectors (muscles or glands that release all kind of stuff, from water to hormones to ear wax) Interneuron They connect sensory neurons and motor neurons. It has a cell body (or soma) and root-like extensions called mygdale. Amongst the mygdale, one major outgoing trunk is the axon, and the others are dendrites. The signal processing capabilities of a neuron is its ability to vary its intrinsic electrical potential (membrane potential) through special electro-physical and chemical processes. The portion of axon immediately adjacent to the cell body is called axon hillock. This is the point at which action potentials are usually generated. The branches that leave the main axon are often called collaterals. Certain types of neurons have axons or dendrites coated with a fatty insulating substance called myelin. The coating is called the myelin sheath and the fiber is said to be myelinated. In some cases, the myelin sheath is surrounded by another insulating layer, sometimes called neurilemma. This layer, thinner than the myelin sheath and continuous over the nodes of Ranvier, is made up o thin cells called Schwann cells. Now, how do these things work? Inside and just outside of the neurons are sodium ions (Na+) and potassium ions (K+). Normally, when the neuron is just sitting not sending any messages, K+ accumulate inside the neuron while Na+ is kicked out to the area just outside the neuron. Thus, there is a lot of K+ in the neuron and a lot of Na+ just outside of it. This is called the resting potential. Keeping the K+ in and the Na+ is not easy; it requires energy from the body to work. An impulse coming in from the dendrites, reverses this balance, causing K+ to leave the neuron and Na+ to come in. This is known as depolarization. As K+ leave Na+ enter the neuron, energy is released, as the neuron no longer is doing any work to keep K+ in and Na+ out. This energycreates an electrical impulse or action potential that is transmitted from the soma to axon. As the impulse leaves the axon, the neuron repolarizes, that is it takes K+ back in and kicks Na+ out and restores itself to resting potential, ready to send another impulse. This process occurs extremely quickly. A neuron theoretically can send roughly 266 messages in one second. The electrical impulse may stimulate other neurons from its synaptic knobs to propagate the message. Experiments have shown that the membrane voltage variation during the generation of an action potential is generally in a form of a spike (a short pulse figure 2.2), and the shape of this pulse in neurons is rather stereotype and mathematically predictable. 2.2 SILICON NEURONS Neuromorphic engineers are more interested in the physiological rather than the anatomical model of a neuron though, which is concerned with the functionality rather than only classifying its parts. And their preference lies with models that can be realized in aVLSI circuits. Luckily many of the models of neurons have always been formulated as electronic circuits since many of the varying observables in biological neurons are voltages and currents. So it was relatively straight forward to implement them in VLSI electronic circuits. There exist now many aVLSI models of neurons which can be classified by their level of detail that is represented in them. A summary can be found in table 3.1. The most detailed ones are known as ‘silicon neurons. A bit cruder on the level of detail are ‘integrate and fire neurons and even more simplifying are ‘Perceptrons also known as ‘Mc Culloch Pitts neurons. The simplest way however of representing a neuron in electronics is to represent neurons as electrical nodes. Table 2.1 VLSI models of neurons 2.2.1 Electrical Nodesasneurons The most simple of all neuronal models is to just represent a neurons activity by a voltage or a current in an electrical circuit, and input and output are identical, with no transfer function in-between. If a voltage node represents a neuron, excitatory bidirectional connections can be realized simply by resistive elements between the neurons. If you want to add the possibility for inhibitory and mono directional connections, followers can be used instead of resistors. Or if a current represents neuronal activity then a simple current mirror can implement a synapse. Many useful processing networks can be implemented in this manner or in similar ways. For example a resistive network can compute local averages of current inputs. 2.2.2 Perceptrons A perceptron is a simple mathematical model of a neuron. As real neurons it is an entity that is connected to others of its kind by one output and several inputs. Simple signals pass through these connections. In the case of the perceptron these signals are not action potentials but real numbers. To draw the analogy to real neurons these numbers may represent average frequencies of action potentials. The output of a perceptron is a monotonic function (referred to as activation function) of the weighted sum of its inputs (see figure 3.3). Perceptrons are not so much implemented in analog hardware. They have originally been formulated as a mathematical rather than an electronic model and traditional computers are good at those whereas it is not so straight forward to implement simple mathematics into aVLSI. Still there exist aVLSI implementations of perceptrons since they still promise the advantage of a real fully parallel, energy and space conservative implementation. A simple aVLSI implementation of a perceptron is given in the schematics in figure 3.4. This particular implementation works well enough in theory, in practice however it is on one hand not flexible enough (particularly the activation function), on the other already difficult to tune by its bias voltages and prone to noise on the a chip. Circuits that have really been used are based on this one but were more extensive to deal with the problems. 2.2.3 Integrate Fire Neurons This model of a neuron sticks closer to the original in terms of its signals. Its output and its inputs are pulse signals. In terms of frequencies it actually can be modeled by a perceptron and vice versa. It is however much better suited to be implemented in aVLSI. And the spike communication also has distinct advantages in noise robustness. That is also thought to be a reason, why the nervous system uses that kind of communication. An integrate and fire neuron integrates weighted charge inputs triggered by presynaptic action potentials. If the integrated voltage reaches a threshold, the neuron fires a short output pulse and the integrator is reset. These basic properties are depicted in figure 2.5. 2.3 BIOLOGICAL SIGNIFICANCE OF NEUROMORPHIC SYSTEMS The fundamental philosophy of neuromorphic engineering is to utilize algorithmic inspiration of biological systems to engineer artificial systems. It is a kind of technology transfer from biology to engineering that involves the understanding of the functions and forms of the biological systems and consequent morphinginto silicon chips. The fundamental biological unit mimicked in the design of neuromorphic systems is the neurons. Animal brain is composed of these individual units of computation, called neurons and the neurons are the elementary signaling parts of the nervous systems. By examining the retina for instance, artificial neurons that mimic the retinal neurons and chemistry are fabricated on silicon (most common material), gallium arsenide (GaAs) or possibly prospective organic semiconductor materials. 2.4 NEUROMORPHIC ELECTRONICS ENGINEERING METHODS Neuromorphic systems design methods involves the mapping of models of perfection and sensory processing in biological systems onto analog VLSI systems which emulate the biological functions at the same time resembling their structural architecture. These systems are mainly designed with complementary metal oxide semiconductors (CMOS) transistors that enable low power consumption, higher chip density and integration, lower cost. These transistors are biased to operate in the sub-threshold region to enable the realizations of high dynamic range of currents which are very important for neural systems design. Elements of adaptation and learning (a sort of higher level of adaptation in which past experience is used to effectively readjust the response of a system to previously unseen input stimuli) are incorporated into neuromorphic systems since they are expected to emulate the behavior of the biological systems and compensate for imperfections in t Modelling of Meromorphic Retina Modelling of Meromorphic Retina CHAPTER 1 INTRODUCTION and literature review 1. INTRODUCTION The world depends on how we sense it; perceive it and how we act is according to our perception of this world. But where from this perception comes? Leaving the psychological part, we perceive by what we sense and act by what we perceive. The senses in humans and other animals are the faculties by which outside information is received for evaluation and response. Thus the actions of humans depend on what they sense. Aristotle divided the senses into five, namely: Hearing, Sight, Smell, Taste and Touch. These have continued to be regarded as the classical five senses, although scientists have determined the existence of as many as 15 additional senses. Sense organs buried deep in the tissues of muscles, tendons, and joints, for example, give rise to sensations of weight, position of the body, and amount of bending of the various joints; these organs are called proprioceptors. Within the semicircular canal of the ear is the organ of equilibrium, concerned with the sense of balance. General senses, which produce information concerning bodily needs (hunger, thirst, fatigue, and pain), are also recognized. But the foundation of all these is still the list of five that was given by Aristotle. Our world is a visual world. Visual perception is by far the most important sensory process by which we gather and extract information from our environment. Vision is the ability to see the features of objects we look at, such as color, shape, size, details, depth, and contrast. Vision is achieved when the eyes and brain work together to form pictures of the world around us. Vision begins with light rays bouncing off the surface of objects. Light reflected from objects in our world forms a very rich source of information and data. The light reflected has a short wavelength and high transmission speed that allow us a spatially accurate and fast localization of reflecting surfaces. The spectral variations in wavelength and intensity in the reflected light resemble the physical properties of object surfaces, and provide means to recognize them. The sources that light our world are usually inhomogeneous. The sun, our natural light source, for example, is in good approximation a point sou rce. Inhomogeneous light sources cause shadows and reflections that are highly correlated with the shape of objects. Thus, knowledge of the spatial position and extent of the light source enables further extraction of information about our environment. Our world is also a world of motion. We and most other animals are moving creatures. We navigate successfully through a dynamic environment, and we use predominantly visual information to do so. A sense of motion is crucial for the perception of our own motion in relation to other moving and static objects in the environment. We must predict accurately the relative dynamics of objects in the environment in order to plan appropriate actions. Take for example the following situation that illustrates the nature of such a perceptual task: the batsman a cricket team is facing a bowler. In order to get the boundary on the ball, he needs an accurate estimate of the real motion trajectory of the ball such that he can precisely plan and orchestrate his body movements to hit the ball. There is little more than just visual information available to him in order to solve the task. And once he is in motion the situation becomes much more complicated because visual motion information now represents the relative motion between him and the ball while the important coordinate frame remains static. Yet, despite its difficulty, with appropriate training some of us become astonishingly good at performing this task. High performance is important because we live in a highly competitive world. The survival of the fittest applies to us as to any other living organism, although the fields of competition might have slightly shifted and diverted during recent evolutionary trends. This competitive pressure not only promotes a visual motion perception system that can determine quickly what is moving where, in which direction, and at what speed; but it also forces this system to be efficient. Efficiency is crucial in biological systems. It encourages solutions that consume the smallest amount of resources of time, substrate, and energy. The requirement for efficiency is advantageous because it drives the system to be quicker, to go further, to last longer, and to have more resources left to solve and perform other tasks at the same time. Thus, being the complex sensory-motor system as the batsman is, he cannot dedicate all of the resources available to solve a single task. Compared to human perceptual abilities, nature provides us with even more astonishing examples of efficient visual motion perception. Consider the various flying insects that navigate by visual perception. They weigh only fractions of grams, yet they are able to navigate successfully at high speeds through complicated environments in which they must resolve visual motions up to 2000 deg/s. 1.1 ARTIFICIAL SYSTEMS What applies to biological systems applies also to a large extent to any artificial autonomous system that behaves freely in a real-world environment. When humankind started to build artificial autonomous systems, it was commonly accepted that such systems would become part of our everyday life by the year 2001. Numberless science-fiction stories and movies have encouraged visions of how such agents should behave and interfere with human society. And many of these scenarios seem realistic and desirable. Briefly, we have a rather good sense of what these agents should be capable of. But the construction is still eluding. The semi- autonomous rover of NASAs recent Mars missions or demonstrations of artificial pets are the few examples. Remarkably the progress in this field is slow than the other fields of electronics. Unlike transistor technology in which explosion of density is defined by the Moores law and also in terms of the computational powers the performance of autonomous systems is still not to the par. To find out the reason behind it we have to understand the limitation of traditional approaches. The autonomous system is the one that perceives, takes decision and plans action at a cognitive level, in doing so it must show some degree of intelligence. Returning back to the batsman example, he knows exactly what he has to do to dispatch the ball to the boundary, he has to get into a right position and then hit the ball with a precise timing. In this process, the photons hit the retina and then muscle force is applied. The batsman is not aware that this much is going on into his body. The batsman has a nervous system, and one of its many functions is to instantiate a transformation layerbetween the environme nt and his cognitive mind. The brain reduces and preprocesses the huge amount of noisy sensory data, categorizes and extracts the relevant information, and translates it into a form that is accessible to cognitive reasoning. Thus it is clear here that the there is cluster of process that takes place in a biological cognitive system in a very short time duration. And also that an important part of this whole process is transduction although it is not the one that can solely perform the whole complex task. Thus perception is the interpretationof sensory information with respect to the perceptual goal. The process is shown in the fig-1. 1.2 DIFFERENCE BETWEEN BIOLOGICAL SYSTEMS AND COMPUTERS The brain is fundamentally differently organized than a computer and science is still a long way from understanding how the whole thing works. A computer is really easy to understand by comparison. Features (or organization principles) that clearly distinguish a brain from a computer are: Massive parallelism, Distributed storage, Asynchronous processing, and Self organization. The computer is still a basically serially driven machine with a centralized storage and minimal self organization. The table 1.1 enlists these differences. Table 1.1 Differences in the organization principles and operation of computer and brain The digital computation may become so fast that it may solve the present problems and also it may become possible that the autonomous systems are made by digital components that are as powerful as efficient and as intelligent as we may imagine in our wildest dreams. However there are doubts in it and so we have to switch to an implementation framework that can realize all these things. 1.3 NEURAL COMPUTATIONS WITH THE HELP OF ANALOG INTEGRATED CIRCUITS It was Carver Mead who, inspired by the course â€Å"The Physics of Computation† he jointly taught with John Hopfield and Richard Feynman at Caltech in 1982, first proposed the idea of embodying neural computation in silicon analog very large-scale integrated (aVLSI) circuits. Biological neural networks are examples of wonderfully engineered and efficient computational systems. When researchers first began to develop mathematical models for how nervous systems actually compute and process information, they very soon realized that one of the main reasons for the impressive computational power and efficiency of neural networks is the collective computation that takes place among their highly connected neurons. And in researches, it is also well established that these computations are not undertaken digitally although the digital way is much simpler. Real neurons have a cell membrane with a capacitance that acts as a low-pass filter to the incoming signal through its dendrites; they have dendritic trees that non-linearly add signals from other neurons, and so forth. Network structure and analog processing seem to be two key properties of nervous systems providing them with efficiency and computational power, but nonetheless two properties that digital compute rs typically do not share or exploit. 1.4 LITERATURE REVIEW 1. Biological information-processing systems operate on completely different principles from those with which most engineers are familiar. For many problems, particularly those in which the input data are ill-conditioned and the computation can be specified in a relative manner, biological solutions are many orders of magnitude more effective than those we have been able to implement using digital methods. This advantage can be attributed principally to the use of elementary physical phenomena as computational primitives, and to the representation of information by the relative values of analog signals, rather than by the absolute values of digital signals. This approach requires adaptive techniques to mitigate the effects of component differences. This kind of adaptation leads naturally to systems that learn about their environment. Large-scale adaptive analog systems are more robust to component degradation and failure than are more conventional systems, and they use far less power . For this reason, adaptive analog technology can be expected to utilize the full potential of wafer scale silicon fabrication 2. The architecture and realization of microelectronic components for a retina-implant system that will provide visual sensations to patients suffering from photoreceptor degeneration. Special circuitry has been developed for a fast single-chip CMOS image sensor system, which provides high dynamic range of more than seven decades (without any electronic or mechanical shutter) corresponding to the performance of the human eye. This image sensor system is directly coupled to a digital filter and a signal processor that compute the so-called receptive-field function for generation of the stimulation data. These external components are wireless, linked to an implanted flexible silicon multielectrode stimulator, which generates electrical signals for electro stimulation of the intact ganglion cells. All components, including additional hardware for digital signal processing and wireless data and power transmission, have been fabricated using in-house standard CMOS technology 3. The circuits inspired by the nervous system that either help verifying neuron physiological models, or that are useful components in artificial perception/action systems. Research also aims at using them in implants. These circuits are computational devices and intelligent sensors that are very differently organized than digital processors. Their storage and processing capacity is distributed. They are asynchronous and use no clock signal. They are often purely analog and operate time continuous. They are adaptive or can even learn on a basic level instead of being programmed. A short introduction into the area of brain research is also included in the course. The students will learn to exploit mechanisms employed by the nervous system for compact energy efficient analog integrated circuits. They will get insight into a multidisciplinary research area. The students will learn to analyze analog CMOS circuits and acquire basic knowledge in brain research methods. 4. Smart vision systems will be an inevitable component of future intelligent systems. Conventional vision systems, based on the system level integration (or even chip level integration) of an image (usually a CCD) camera and a digital processor, do not have the potential for application in general purpose consumer electronic products. This is simply due to the cost, size, and complexity of these systems. Because of these factors conventional vision systems have mainly been limited to specific industrial and military applications. Vision chips, which include both the photo sensors and parallel processing elements (analog or digital), have been under research for more than a decade and illustrate promising capabilities. 5. Dr. Carver Mead, professor emeritus of California Institute of Technology (Caltech), Pasadena pioneered this field. He reasoned that biological evolutionary trends over millions of years have produced organisms that engineers can study to develop better artificial systems. By giving senses and sensory-based behavior to machines, these systems can possibly compete with human senses and brings an intersection between biology, computer science and electrical engineering. Analog circuits, electrical circuits operated with continuous varying signals, are used to implement these algorithmic processes with transistors operated in the sub-threshold or weak inversion region (a region of operation in which transistors are designed to conduct current though the gate voltage is slightly lower than the minimum voltage, called threshold voltage, required for normal conduction to take place) where they exhibit exponential current voltage characteristics and low currents. This circuit paradigm pr oduces high density and low power implementations of some functions that are computationally intensive when compared with other paradigms (triode and saturation operational regions). {A triode region is operating transistor with gate voltage above the threshold voltage but with the drain-source voltage lower than the difference between the gate-source voltage and threshold voltage. For saturation region, the gate voltage is still above the threshold voltage but with the drain-source voltage above the difference between the gate-source voltage and threshold voltage. Transistor has four terminals: drain, gate, source and bulk. Current flows between the drain and the source when enough voltage is applied through the gate that enables conduction. The bulk is the body of the transistor.}. As the systems mature, human parts replacements would become a major application area of the Neuromorphic electronics. The fundamental principle is by observing how biological systems perform these func tions robust artificial systems are designed. 6. In This proposed work a circuit level model of Neuromorphic Retina, this is a crude electronic model of biologically inspired smart visual sensors. These visual sensors have integrated image acquisition and parallel processing. Having these features neuromorphic retina mimics the neural circuitry of bionic eye. The proposed electronic model contains adaptive photoreceptors as light sensors and other circuit components such as averaging circuits, circuits representing ganglion cells, neuronal firing circuits etc that junction to sense brightness, size, orientation and shape to distinguish objects in closer proximity. Although image-processing features are available with modern robots but most of the issues related to image processing are taken care by software resources. Whereas machine vision with the help of neuromorphic retina is empowered with image processing at the front end. With added hardware resources, processing at the front end can reduce a lot of engineering resources for making electronic devices with sense of vision. 1.5 OBJECTIVES OF THE PRESENT WORK This project work describes a circuit level model of Neuromorphic Retina, which is a crude electronic model of biologically inspired smart visual sensors. These visual sensors have integrated image acquisition and parallel processing. Having these features neuromorphic retina mimics the neural circuitry of bionic eye. The proposed electronic model contains adaptive photoreceptors as light sensors and other neural firing circuits etc at junction to sense brightness, size, orientation and shape to distinguish objects in closer proximity. Although, image processing features are available with modern robots but most of the issues related to image processing are taken care by software resources. Whereas, machine vision with the help of neuromorphic retina is empowered with image processing at the front end. In this paper it has been shown that with added hardware resources, processing at the front end it can reduce a lot of engineering resources as well as time for making electronic devic es with sense of vision. . The objectives of present work are: Modelling of Neuromorphic Retina The photoreceptor block The horrizontal cell block The transistor mesh implemented with cmos technology The integerated block The integrated block of prs, horizontal cells and bipolar cells The spike generation circuit 1.6 Concluding Remarks In this chapter, the function of the artificial system, difference between brain and computer work is described. The present work is focused on designing of neuromorphic retina layer circuits. Many successful studies have been carried out by the researchers to study the behavior and failure of neuromorphic retina. Some investigators have performed the experimental work to study the phenomenon of the neuromorphic retina. Chapter 2 conations the biological neurons and the electronics of neuromorphic retina in this the descriptions of silicon neurons, electrical nodes as neurons, perceptrons, integrate fire neurons, biological significance of neuromorphic systems, neuromorphic electronics engineering methods, process of developing a neuromorphic chip. Chapter 3 describes the artificial silicon retina, physiology of vision, the retina, photon to electrons, why we require the neuromorphic retina?, the equivalent electronic structure, visual path to brain. In chapter 4 designing and implementation of neuromorphic retina in this the description of the photoreceptor block, the horrizontal cell block, the integerated block, the integrated block of photoreceptors, horizontal cells and bipolar cells, the spike generation circuit. In chapter 5 the design analyses and test results of neuromorphic retina layers. The results are summarized in the form of conclusion in Chapter 6 CHAPTER-2 BIOLOGICAL neurons AND neuromorphic electronics 2.1 INTRODUCTION Neuromorphic systems are inspired by the structure, function and plasticity of biological nervous systems. They are artificial neural systems that mimic algorithmic behavior of the biological animal systems through efficient adaptive and intelligent control techniques. They are designed to adapt, learn from their environments, and make decisions like biological systems and not to perform better than them. There are no efforts to eliminate deficiencies inherent in biological systems. This field, called Neuromorphic engineering, is evolving a new era in computing with a great promise for future medicine, healthcare delivery and industry. It relies on plenty of experiences which nature offers to develop functional, reliable and effective artificial systems. Neuromorphic computational circuits, designed to mimic biological neurons, are primitives based on the optical and electronic properties of semiconductor materials 2.1 BIOLOGICAL NEURONS Biological neurons have a fairly simple large-scale structure, although their operation and small-scale structure is immensely complex. Neurons have three main parts: a central cell body, called the soma, and two different types of branched, treelike structures that extend from the soma, called dendrites and axons. Information from other neurons, in the form of electrical impulses, enters the dendrites at connection points called synapses. The information flows from the dendrites to the soma, where it is processed. The output signal, a train of impulses, is then sent down the axon to the synapses of other neurons. The dendrites send impulses to the soma while the axon sends impulses away from the soma. Functionally, there are three different types of neurons: Sensory neurons They carry information from sense receptors (nerves that help us see, smell, hear taste and feel) to the central nervous system which includes the brain and the spinal cord. Motor neurons They carry information from the CNS to effectors (muscles or glands that release all kind of stuff, from water to hormones to ear wax) Interneuron They connect sensory neurons and motor neurons. It has a cell body (or soma) and root-like extensions called mygdale. Amongst the mygdale, one major outgoing trunk is the axon, and the others are dendrites. The signal processing capabilities of a neuron is its ability to vary its intrinsic electrical potential (membrane potential) through special electro-physical and chemical processes. The portion of axon immediately adjacent to the cell body is called axon hillock. This is the point at which action potentials are usually generated. The branches that leave the main axon are often called collaterals. Certain types of neurons have axons or dendrites coated with a fatty insulating substance called myelin. The coating is called the myelin sheath and the fiber is said to be myelinated. In some cases, the myelin sheath is surrounded by another insulating layer, sometimes called neurilemma. This layer, thinner than the myelin sheath and continuous over the nodes of Ranvier, is made up o thin cells called Schwann cells. Now, how do these things work? Inside and just outside of the neurons are sodium ions (Na+) and potassium ions (K+). Normally, when the neuron is just sitting not sending any messages, K+ accumulate inside the neuron while Na+ is kicked out to the area just outside the neuron. Thus, there is a lot of K+ in the neuron and a lot of Na+ just outside of it. This is called the resting potential. Keeping the K+ in and the Na+ is not easy; it requires energy from the body to work. An impulse coming in from the dendrites, reverses this balance, causing K+ to leave the neuron and Na+ to come in. This is known as depolarization. As K+ leave Na+ enter the neuron, energy is released, as the neuron no longer is doing any work to keep K+ in and Na+ out. This energycreates an electrical impulse or action potential that is transmitted from the soma to axon. As the impulse leaves the axon, the neuron repolarizes, that is it takes K+ back in and kicks Na+ out and restores itself to resting potential, ready to send another impulse. This process occurs extremely quickly. A neuron theoretically can send roughly 266 messages in one second. The electrical impulse may stimulate other neurons from its synaptic knobs to propagate the message. Experiments have shown that the membrane voltage variation during the generation of an action potential is generally in a form of a spike (a short pulse figure 2.2), and the shape of this pulse in neurons is rather stereotype and mathematically predictable. 2.2 SILICON NEURONS Neuromorphic engineers are more interested in the physiological rather than the anatomical model of a neuron though, which is concerned with the functionality rather than only classifying its parts. And their preference lies with models that can be realized in aVLSI circuits. Luckily many of the models of neurons have always been formulated as electronic circuits since many of the varying observables in biological neurons are voltages and currents. So it was relatively straight forward to implement them in VLSI electronic circuits. There exist now many aVLSI models of neurons which can be classified by their level of detail that is represented in them. A summary can be found in table 3.1. The most detailed ones are known as ‘silicon neurons. A bit cruder on the level of detail are ‘integrate and fire neurons and even more simplifying are ‘Perceptrons also known as ‘Mc Culloch Pitts neurons. The simplest way however of representing a neuron in electronics is to represent neurons as electrical nodes. Table 2.1 VLSI models of neurons 2.2.1 Electrical Nodesasneurons The most simple of all neuronal models is to just represent a neurons activity by a voltage or a current in an electrical circuit, and input and output are identical, with no transfer function in-between. If a voltage node represents a neuron, excitatory bidirectional connections can be realized simply by resistive elements between the neurons. If you want to add the possibility for inhibitory and mono directional connections, followers can be used instead of resistors. Or if a current represents neuronal activity then a simple current mirror can implement a synapse. Many useful processing networks can be implemented in this manner or in similar ways. For example a resistive network can compute local averages of current inputs. 2.2.2 Perceptrons A perceptron is a simple mathematical model of a neuron. As real neurons it is an entity that is connected to others of its kind by one output and several inputs. Simple signals pass through these connections. In the case of the perceptron these signals are not action potentials but real numbers. To draw the analogy to real neurons these numbers may represent average frequencies of action potentials. The output of a perceptron is a monotonic function (referred to as activation function) of the weighted sum of its inputs (see figure 3.3). Perceptrons are not so much implemented in analog hardware. They have originally been formulated as a mathematical rather than an electronic model and traditional computers are good at those whereas it is not so straight forward to implement simple mathematics into aVLSI. Still there exist aVLSI implementations of perceptrons since they still promise the advantage of a real fully parallel, energy and space conservative implementation. A simple aVLSI implementation of a perceptron is given in the schematics in figure 3.4. This particular implementation works well enough in theory, in practice however it is on one hand not flexible enough (particularly the activation function), on the other already difficult to tune by its bias voltages and prone to noise on the a chip. Circuits that have really been used are based on this one but were more extensive to deal with the problems. 2.2.3 Integrate Fire Neurons This model of a neuron sticks closer to the original in terms of its signals. Its output and its inputs are pulse signals. In terms of frequencies it actually can be modeled by a perceptron and vice versa. It is however much better suited to be implemented in aVLSI. And the spike communication also has distinct advantages in noise robustness. That is also thought to be a reason, why the nervous system uses that kind of communication. An integrate and fire neuron integrates weighted charge inputs triggered by presynaptic action potentials. If the integrated voltage reaches a threshold, the neuron fires a short output pulse and the integrator is reset. These basic properties are depicted in figure 2.5. 2.3 BIOLOGICAL SIGNIFICANCE OF NEUROMORPHIC SYSTEMS The fundamental philosophy of neuromorphic engineering is to utilize algorithmic inspiration of biological systems to engineer artificial systems. It is a kind of technology transfer from biology to engineering that involves the understanding of the functions and forms of the biological systems and consequent morphinginto silicon chips. The fundamental biological unit mimicked in the design of neuromorphic systems is the neurons. Animal brain is composed of these individual units of computation, called neurons and the neurons are the elementary signaling parts of the nervous systems. By examining the retina for instance, artificial neurons that mimic the retinal neurons and chemistry are fabricated on silicon (most common material), gallium arsenide (GaAs) or possibly prospective organic semiconductor materials. 2.4 NEUROMORPHIC ELECTRONICS ENGINEERING METHODS Neuromorphic systems design methods involves the mapping of models of perfection and sensory processing in biological systems onto analog VLSI systems which emulate the biological functions at the same time resembling their structural architecture. These systems are mainly designed with complementary metal oxide semiconductors (CMOS) transistors that enable low power consumption, higher chip density and integration, lower cost. These transistors are biased to operate in the sub-threshold region to enable the realizations of high dynamic range of currents which are very important for neural systems design. Elements of adaptation and learning (a sort of higher level of adaptation in which past experience is used to effectively readjust the response of a system to previously unseen input stimuli) are incorporated into neuromorphic systems since they are expected to emulate the behavior of the biological systems and compensate for imperfections in t