Difference between revisions of "Bilingual education" - New World Encyclopedia

From New World Encyclopedia
Line 7: Line 7:
  
 
==Development of Bilingual Educational Programs==
 
==Development of Bilingual Educational Programs==
Bilingual programs are created so children can be able to either maintain their own cultures, identities, heritages and languages and/or explore new ones. Teachers are faced with the question of how to best assimilate students that don’t speak the native language into the classroom.
+
Bilingual programs are created so students can be able to either maintain their own cultures, identities, heritages and languages and/or explore new ones. Teachers are faced with the question of how to best assimilate students that don’t speak the native language into the classroom.
  
 
There are two main goals of bilingual education. First is the development of the academic native language and school success. The second important issue is the heritage language. In order to promote diversity it is crucial to acknowledge peoples' differences and facilitate the ability for them to keep their dignity and spirit alive while allowing the growth of present and future forms of language programs.
 
There are two main goals of bilingual education. First is the development of the academic native language and school success. The second important issue is the heritage language. In order to promote diversity it is crucial to acknowledge peoples' differences and facilitate the ability for them to keep their dignity and spirit alive while allowing the growth of present and future forms of language programs.
Line 129: Line 129:
  
 
===Challenges===
 
===Challenges===
 +
The effectiveness of bilingual programs relies on how well the program is designed and implemented. Above all, good teachers are imperative to the success of the program.  The question of how the languages are used in the classroom is an ongoing challenge.  Do the teachers simply give the translations or do they engage the students in cognitive and academic growth?  Is the program goal to provide a “quick exit” to the mainstream classroom or is the goal to encourage fluency in speech and reading?
 +
 +
When studies on the effectiveness of bilingual programs include both good and bad programs averaged together, the results are basically mediocre. However, when the research tested programs that featured a gradual transition verses the “quick exit” and immersion programs, the study found that the transitional bilingual programs were significantly more successful. <ref> [http://www.nabe.org/documents/research/Ramirez.pdf  ''Longitudinal Study of Structured English Immersion Strategy, Early-Exit
 +
and Late-Exit Transitional Bilingual Education Programs for Language-
 +
Minority Children'' by J. David Ramírez,
 +
Sandra D. Yuen, and 
 +
Dena R. Ramey (1991)] retrieved on December 21, 2007. </ref> <ref> [http://www.cal.org/crede/pubs/ResBrief10.htm ''A National Study of School Effectiveness for Language Minority Students' Long-Term Academic Achievement'' by the Center for Research on Education, Diversity & Excellence
 +
(January 2003)] retrieved on December 21, 2007. </ref>
 +
 +
Another challenge schools experience is providing adequate resources, materials, and support services. The absence of books limits the component of free voluntary reading that can accelerate the learning of the language.  Books, in both first and second languages, are vital for comprehensive input in the language as well as a means for developing the knowledge and literacy both for learning the language and for the language development.
  
 
==Notes==
 
==Notes==

Revision as of 20:59, 21 December 2007



Bilingual education involves teaching all subjects in school through two different languages and the practice of teaching children in their native language. Instruction occurs in the native language and a minority language with varying amounts of each language used in accordance with the program model. There are many forms of bilingual education, and the implementation of these programs in the educational system varies significantly. Often bilingual programs are set up to facilitate the opportunity for children to progress in their subjects such as math, science, and social studies in their native tongue while they learn their second language in a separate class. The purpose of bilingual education was as a transitional program, but often students continue in such programs for most of their school years.

Development of Bilingual Educational Programs

Bilingual programs are created so students can be able to either maintain their own cultures, identities, heritages and languages and/or explore new ones. Teachers are faced with the question of how to best assimilate students that don’t speak the native language into the classroom.

There are two main goals of bilingual education. First is the development of the academic native language and school success. The second important issue is the heritage language. In order to promote diversity it is crucial to acknowledge peoples' differences and facilitate the ability for them to keep their dignity and spirit alive while allowing the growth of present and future forms of language programs.

Since many children in America during the 1840s spoke German, Dutch, French, Spanish, Swedish, and other languages, the tradition of public bilingual education began. However, after World War I, laws prohibiting instruction in languages other than English were put in place restricting bilingual education. The situation of bilingual education in the 1960s, with the civil rights movements, witnessed a renewed interest. In 1968, The United States Congress started to provide funding for bilingual programs.

In 1974, the U.S. Supreme Court ruled that 1800 Chinese students in San Francisco were not receiving a "meaningful education" because they had English-only instruction. The public schools were asked to provide special programs for students who spoke little or no English. The use for special language program funding for both minority language and mainstream groups in the United States increased from $7.5 million in 1969 to $117 million in 1995.

Examples Worldwide

Andalucia

In Andalucia (southernmost region of Spain) things have changed drastically concerning bilingual education since the introduction of the Plurilingualism Promotion Plan by the autonomous government. The plan was born as the realization for the Andalucian territory of the European language policies regarding the teaching and learning of languages. With special strength in the past ten years, the Council of Europe has been encouraging governments and education authorities to design new schemes on the teaching and learning of languages, inclusive of the mother tongue, which enhance communication targets, rather than descriptive or reflexive knowledge, as well as the promotion of language diversity, intercultural values and democratic citizenship.

In addition to this new European scene, the Scheme for the Promotion of Plurilingualism has learned a lot from the first experimental bilingual sections set up in some schools by the Andalusian government in 1998. Following the content-based approach, French and German were used to partly teach other subjects. This successful experience, as show the international tests that the students have been given, is the starting point for a more ambitious scene, where 400 schools will be involved in the next four years, more languages, especially English, will take part, and a lot of investigation and implementation of the Integrated Curriculum of languages must be carried out.

Being aware of the necessity of the Andalucian people to adapt to the new scenario, a major government plan, called “strategies for the second modernization of Andalusia”, was designed in 2003. The document also underlined language diversity as a source of richness and a valuable heritage of humankind which needs to be looked after.

Therefore, the major goal of the Scheme for the Promotion of Plurilingualism is to design a new language policy for Andalusia, according to the principles of the European Council, in order to provide the citizens with the plurilingual and multicultural competence to respond to the new economic, technological and social challenges, based on an Integrated Curriculum for all languages and key stages.

The full version in English of the Plurilingualism Promotion Plan can be found online. [1]

Australia

In Australia there are some schools with bilingual programs which cater for children speaking community languages other than English. Baldauf (2005) explains that these programs are now beginning to benefit from more government support. Bilingual education for Indigenous students, however, has only received intermittent official backing. In the Northern Territory, for example, bilingual programs for Indigenous students were begun with Federal Government support in the early 1970s but by December 1998 the Northern Territory Government had announced its decision to shift $3 million away from the 21 bilingual programs to a Territory-wide program teaching English as a second language. Within 12 months though the government had softened its position. Most bilingual programs were allowed to continue under the guise of two-way education. Then on August 24, 2005 the Minister for Employment, Education, and Training announced that the government would be "revitalising bi-lingual education" at 15 Community Education Centres. (Alekerange, Angurugu, Borroloola, Gapuwiyak, Gunbalunya, Kalkaringi, Lajamanu, Maningrida, Milingimbi, Ramingining, Ngkurr, Shepherdson College, Numbulwar, Yirrkala and Yuendumu). This revitalization is conceived as part of an effort aimed at "providing effective education from pre-school through to senior secondary at each of the Territory’s 15 Community Education Centres". As Harris & Devlin (1986) observe, “Aboriginal bilingual education in Australia represents much more than a range of education programs. It has been a measure of non-Aboriginal commitment to either assimilation or cultural pluralism”.

Canada

In Canada, education is under provincial jurisdiction. However, the federal government has been a strong supporter of establishing Canada as a bilingual country and has helped pioneer the French immersion programs in the public education systems throughout Canada. In French immersion students with no previous French language training, usually beginning in Kindergarten or grade 1, do all of their school work in French. Regular English programs provide Core French in later grades, usually in grade 4. Depending on provincial jurisdiction, some provinces also offer an Extended French program that begins in grade 7 which offers relatively more courses in French. There are also some private schools and preschools that do immersion programs in other languages.

European Union

Near most of the various European Union institution sites, European Schools have been created to allow staff to have their students receive their education in their mother tongue, and at the same time to foster European spirit by (among other things) teaching at least two other European languages.

Basic instruction is given in the eleven official languages of the European Union: Danish, Dutch, English, Finnish, French, German, Greek, Italian, Portuguese, Spanish and Swedish. In the expansion of the Union with 10 countries in 2004 and two more in 2007, the new official languages of the EU are added. The pupil's mother tongue (L I) therefore remains his/her first language throughout the School. Consequently, each School comprises several language sections. The curricula and syllabuses (except in the case of mother tongue) are the same in all sections. In the Schools where the creation of a separate language section cannot be justified based on the number of students, teaching of the mother tongue and possibly mathematics is provided.

To foster the unity of the School and encourage genuine multicultural education, there is a strong emphasis on the learning, understanding and use of foreign languages. This is developed in a variety of ways. The study of a first foreign language (English, French or German, known as L II) is compulsory throughout the school, from first year primary up to the Baccalaureate. In secondary school, some classes will be taught in L II. All pupils must study a second foreign language (L III), starting in the second year of secondary school. Any language available in the School may be chosen. Pupils may choose to study a third foreign language (L IV) from the fourth year of secondary school. Language classes are composed of mixed nationalities and taught by a native speaker. A weekly "European Hour" in the primary school brings together children from all sections for cultural and artistic activities and games. In the secondary school, classes in art, music and sport are always composed of mixed nationalities. From the third year of secondary school, history and geography are studied in the pupil's first foreign language, also called the "working language" (English, French or German). Economics, which may be taken as an option from the fourth year of the secondary school, is also studied in a working language. From the third year, therefore, all social science subjects are taught to groups of mixed nationalities. [2]

Israel

Hand in Hand: Center for Jewish Arab Education in Israel runs four Hebrew-Arabic bilingual schools, and the Neve Shalom peace village also hosts a local school which conducts classes in both Hebrew and Arabic. Normally students are taught in one language or the other, with most Arab Israelis learning Hebrew as a second language in school.

Middle East

Schools in the Middle East follow the Dual or Triple Language Program. The Triple Language Program is most commonly found in Lebanon. History, grammar, literature and the arabic language are taught in the native language(Arabic). Math and Science are taught in English. In Lebanon, however, the Sciences and Math are taught in either French or English, but it mostly depends on the school's administration or the grade level. It is not uncommon in the Middle East where you could find a French-only school or an English-only school.

Most Arab countries have required mastery in Arabic and English, and some require three. Armenians and other non-Arab minorities are polyglots, especially in Lebanon. Many Armenians can speak 4 languages.

There is a sizable minority of illiterate Arabs but most of these people are bilingual or trilingual but because of vast differences in proper Arabic and colluqial Arabic, many Arabs are unable to differentiate between the two, which is also very common in Western nations too. [3]

Hong Kong

In Hong Kong where both English and Chinese are official, both languages are taught in school and are mandatory subjects. Either English or Chinese is used as the medium of instruction for other subjects.

Southeast Asia

Since the mid-1990s bilingual approaches to schooling and higher education have become popular in parts of Southeast Asia, especially in Thailand and Malaysia where different models have been applied, from L2 immersion (content taught in a non-native language) to parallel immersion, where core subjects are taught in both the mother-tongue and a second language (usually English). Malaysian government policy mandates the phased introduction of English immersion for Math, Science and IT. The Sarasas model, pioneered by the Sarasas schools affiliation in Thailand, is an exemplar of parallel immersion.

The difficulties and disputes characteristic of the US experience have not been replicated in these Asian countries, though they are not without controversy. Generally, it can be said that there is widespread acknowledgement of the need to improve English competence in the population, and bilingual approaches, where language is taught through subject content, are seen to be the most effective means of attaining this. The most significant limiting factors are the shortage of teachers linguistically competent to teach in a second language and the costs involved in use of expatriate native speakers for this purpose.

The Netherlands

In the Netherlands, there are around 100 bilingual schools. In these schools, some subjects are taught in English, some in Dutch. Most schools are TVWO (Bilingual Preparatory Scientific Education), but there is THAVO (Bilingual Higher General Secondary Education), too. The following subjects are taught in English: Arts, Chemistry, Physics, Biology, Geography, Economics, Physical Education, Drama, English, Mathematics, History and Religious Studies.

The Philippines

Having two official languages, the Philippine constitution provides a clear guideline for the use of both English and Filipino in classrooms.

Presently, the Department of Education is already implementing a rule wherein subjects like English and the Sciences (including Maths) are taught in English while History and Civics are being taught in Filipino.

United States

Bilingual education in the U.S. focuses on English language learners. The term "limited English proficiency" remains in use by the federal government, but has fallen out of favor elsewhere for its negative connotations, so the term "English language learner" (or ELL) is now preferred in schools and educational research. An English language learner is a student who comes from a home where a language other than English is spoken, and who needs language support services in order to succeed in school. Because such students are learning English, they may be denied the opportunity to successfully achieve in classrooms where the language of instruction is English. They may also be unable to participate fully in society.

In the 50 states of the United States, proponents of the practice argue that it will not only help to keep non-English-speaking children from falling behind their peers in math, science, and social studies while they master English, but such programs teach English better than English-only programs. For many students, the process of learning literacy and a new language simultaneously is simply an overwhelming task, so bilingual programs began as a way to help such students develop native language literacy first - research by Cummins (1997), a central researcher in the field, shows that skills such as literacy developed in a first language will transfer to English. Opponents of bilingual education argue that it delays students' mastery of English, thereby retarding the learning of other subjects as well. In California there has been considerable politicking for and against bilingual education.

In 1968 U.S., with Title VII of the Elementary and Secondary Education Act, or, informally, the Bilingual Education Act, Congress first mandated bilingual education in order to give immigrants access to education in their “first” language. (The Act was amended in 1988).

A 1974 U.S. Supreme Court ruling, Lau v. Nichols gave further momentum to bilingual education. Here, the Court held that California schools violated minority language students' rights when they educated students without special provisions. [4]

Taken together, the Bilingual Education Act and the Lau v. Nichols ruling mandated that schools needed to at least provide some type of services to support English language learners, though neither specified what type of educational program needed to be provided. As such both bilingual and English-only programs flourished after the law's passage.

Most recently, however, the Bilingual Education Act was terminated in 2001 by new federal education policy, with the passage of "No Child Left Behind" by U.S. Congress. This law offers no support for native language learning, but rather emphasized accountability in English only, and mandates that all students, including ELLs, are tested yearly in English.

The majority of U.S. high school students in the United States are required to take at least 1 to 2 years of a second language. The vast majority of these classes are either French or Spanish. In a large number of schools this is taught in a manner known as FLES, in which students learn about the second language in a manner similar to other subjects such as Math or Science. Some schools use an additional method known as FLEX in which the "nature of the language" and culture are also taught. High school education almost never uses "immersion" techniques.

Bilingual models

Transitional Bilingual Education involves education in a child's native language, typically for no more than three years, to ensure that students do not fall behind in content areas like math, science, and social studies while they are learning English. The goal is to help students transition to mainstream, English-only classrooms as quickly as possible, and the linguistic goal of such programs is English acquisition only. The overwhelming majority of bilingual programs in the U.S. are transitional.[5]

Two-Way or Dual Language Bilingual Education programs are designed to help native and non-native English speakers become bilingual and biliterate. Ideally in such programs in a U.S. context, half of the students will be native speakers of English and half of the students will be native speakers of a minority language such as Spanish. Dual Language programs are less commonly permitted in US schools, although research indicates they are extremely effective in helping students learn English well and aiding the long-term performance of English learners in school. [6]

One of the most effective forms of Bilingual Education is a type of Dual Language program that has students study in two different ways. 1) A variety of academic subjects are taught in the students' second language, with specially trained bilingual teachers who can understand students when they ask questions in their native language, but always answer in the second language. 2) Native language literacy classes improve students writing and higher-order language skills in their first language. Research has shown that many of the skills learned in the native language can be transferred easily to the second language later. In this type of program, the native language classes do not teach academic subjects. The second-language classes are content-based, rather than grammar-based, so students learn all of their academic subjects in the second language. [7]

Late-Exit or Developmental Bilingual Education. Education is in the child's native language for an extended duration, accompanied by education in English. The goal is to develop bilingualism and biliteracy in both languages. This program is available to students whose native language is not English, and also less common than transitional programs.

Immersion Bilingual Education uses the standard school curriculum taught in a foreign language to those who all speak the same first language. Instruction for all subject matter is given in the foreign language and is not a separate subject. In order to communicate, teachers use gestures, toys, and pictures to explore math, reading, social studies, science etc. Canada has successfully used this program since 1965. In Ottawa and Montreal, 20 % of all English speaking children are taught only in French. Not until the students are able to read in French will they begin instruction in English. By 1999, approximately 162,500 students were enrolled in the French immersion programs in Canada (outside of Quebec). [8] In North America, although Spanish and French immersion programs are most common, other immersion programs such as German, Japanese, and Chinese can be found.

Controversy and Challenges

Controversy

There has been much debate over bilingual education in recent times.

Proponents of bilingual education say that it is not only easier for students to learn a second language if they are literate in their first language, but that such students will learn better and become bilingual and biliterate. [9] Effective bilingual programs strive to achieve proficiency in both the native language and the students' home language. Dual language or Two-Way bilingual programs are one such approach, whereby half of the students speak the native language and half are considered second language language learners. The teacher instructs in the native language and the second language. The dual purpose of this type of classroom is to teach the children a new language and culture, and language diversity in such classrooms is seen as a resource. Programs in the native language only eradicate the native languages immigrants bring to the country, while dual language bilingual programs serve to maintain such languages in an "additive" context, where a new language is added without the first being lost.

Opponents of bilingual education claim that many bilingual education programs fail to teach students the native language. Critics of bilingual education have claimed that studies supporting bilingual education tend to have poor methodologies and that there is little empirical support in favor of it. And often, the "supporting research" is decades old. Results of more recent studies refute earlier claims and instead encourage simultaneous bilingualism.

The controversy over bilingual education is often enmeshed in a larger political and cultural context. Opponents of bilingual education are sometimes accused of racism and xenophobia. This is especially so in the case of such groups as "English First" [10] which is a conservative organization that promotes the stance that English should be the official language of the United States.

Proponents of bilingual education are frequently accused of practicing identity politics to the detriment of children and of immigrants.

Most often, decisions about what language(s) will be the used in instruction in school are decided by political agendas and efforts for social control, rather than by educational research showing which pedagogies in schools work best.

California

California is the state with the highest number of English Learners (ELs) in the nation. One every four students is an EL in California. In June of 1998 Proposition 227 was passed by 61 percent of the California electorate. This proposition mandates that ELs be placed in structured English immersion for a period "not normally to exceed one year", then be transferred to mainstream classrooms taught "overwhelmingly in English". [11] This proposition also gave parents the possibility to request alternative programs for their children, however, the availability of waivers and information to parents have been a challenge in the implementation of this proposition Parrish et al., (2002). "Proposition 227 and Instruction of English Learners in California: Evaluation Update" [12]

In 2000, the California Department of Education contracted with the American Institutes for Research (AIR) and WestEd to conduct a five-year evaluation of the effects of Proposition 227. [13] The study methodology focused on "A combination of student achievement analysis, phone interviews, case study site visits, and written surveys was used to examine such questions as how the proposition was implemented, which EL services are most and least effective, and what unintended consequences resulted from Proposition 227’s implementation."

The authors caution about the limitations in the statewide data. California does not have the capacity to link student academic progress over time across years, however, using student-level linked data over time from the Los Angeles Unified School District, and complementing that analysis with surveys, site visits and interviews, the study found "no conclusive evidence favoring one instructional program over another". Students who remained in bilingual education have similar academic growth trajectories when compared with students that switched to English Immersion. [14]

Arizona

California was followed by Arizona in the passage of similar legislation Arizona "Proposition 203" [15] which ended several programs previously available to ESL students. The Arizona law is even more restrictive, particularly under the implementation of Superintendent of Public Instruction.

Challenges

The effectiveness of bilingual programs relies on how well the program is designed and implemented. Above all, good teachers are imperative to the success of the program. The question of how the languages are used in the classroom is an ongoing challenge. Do the teachers simply give the translations or do they engage the students in cognitive and academic growth? Is the program goal to provide a “quick exit” to the mainstream classroom or is the goal to encourage fluency in speech and reading?

When studies on the effectiveness of bilingual programs include both good and bad programs averaged together, the results are basically mediocre. However, when the research tested programs that featured a gradual transition verses the “quick exit” and immersion programs, the study found that the transitional bilingual programs were significantly more successful. [16] [17]

Another challenge schools experience is providing adequate resources, materials, and support services. The absence of books limits the component of free voluntary reading that can accelerate the learning of the language. Books, in both first and second languages, are vital for comprehensive input in the language as well as a means for developing the knowledge and literacy both for learning the language and for the language development.

Notes

  1. Plurilingualism Promotion Plan[1] retrieved on November 9, 2007
  2. "European Schools Principles and objectives"[2]
  3. "European Schools Principles and objectives"[3] retrieved December 19, 2007.
  4. Bilingual Education Is A Human and Civil Right [4] retrieved November 7, 2007 from the Rethinking Schools Online website.
  5. Transitional Bilingual Education[5] retrieved November 9, 2007 from the Exploring Bilingual Education website.
  6. Project 1.2 Two-Way Immersion Report November, 2004 [6] retrieved November 9, 2007 from the Center for Applied Linguistics website.
  7. Portraits of Success[7] retrieved November 9, 2007 from the National Association for Bilingual Education (NABE) website.
  8. Exploring Bilingual Education retrieved December 19, 2007.
  9. Krashen, S.D. (1999). Bilingual Education: Arguments for and (Bogus) Arguments Against, [8]
  10. What is English First? [9] retrieved on November 9, 2007 from the English First website.
  11. Proposition 227[10] retrieved November 9, 2007 from the California Secretary of State Government website.
  12. Proposition 227 and Instruction of English Learners in California [11] retrieved November 9, 2007.
  13. [12] retrieved November 9, 2007 from the American Institutes for Research (AIR) website.
  14. Effects of the Implementation of Proposition 227 on the Education of English Learners, K-12: 2002 Report By: Thomas B. Parrish, Robert Linquanti, Amy Merickel, [13] retrieved November 9, 2007 from the West Ed website.
  15. Proposition 203 [14] retrieved November 9, 2007 from the Arizona Secretary of State Government website.
  16. [http://www.nabe.org/documents/research/Ramirez.pdf Longitudinal Study of Structured English Immersion Strategy, Early-Exit and Late-Exit Transitional Bilingual Education Programs for Language- Minority Children by J. David Ramírez, Sandra D. Yuen, and Dena R. Ramey (1991)] retrieved on December 21, 2007.
  17. [http://www.cal.org/crede/pubs/ResBrief10.htm A National Study of School Effectiveness for Language Minority Students' Long-Term Academic Achievement by the Center for Research on Education, Diversity & Excellence (January 2003)] retrieved on December 21, 2007.


Further reading

  • Crawford, James, Educating English Learners: Language Diversity in the Classroom (5th edition), Los Angeles: Bilingual Educational Services (BES), June 2004, ISBN 0890759995
  • Dean, Bartholomew (Ed.) (2004) “Indigenous Education and the Prospects for Cultural Survival”, Cultural Survival Quarterly,(27)4.[15]
  • Gao, Helen. (November 2004). “Fight over bilingual education continues.” The San Diego Union-Tribune. [16] retrieved November 9, 2007 from the San Diego Union Tribune website.
  • Cenoz, Jasone & Genesee, Frank, Beyond bilingualism: Multilingualism and multilingual education (pp. 192-205). Clevedon, England: Multilingual Matters, November 1998, ISBN 1853594210
  • Grimes, B.F.. Ethnologue: Languages of the world Dallas, TX: Summer Institute of Linguistics, 1992 [17]
  • Hakuta, Kenji, Mirror of language: The debate on bilingualism. New York: Basic Books, July 1987, ISBN 0465046371
  • Kalist, David E. (2005). "Registered Nurses and the Value of Bilingualism." Industrial & Labor Relations Review, 59(1): 101-118.[18]
  • Harris, S.G. & Devlin, B.C. (1997). "Bilingual programs involving Aboriginal languages in Australia". In Jim Cummins and David Corso (Eds.), Encyclopedia of language and education, vol 5, pp. 1–14. Dordrecht: Kluwer Academic Publishers, ISBN 0792348060
  • Kloss, Heinz (1977, reprinted 1998). The American Bilingual Tradition. (Language in Education; 88) McHenry, IL: Center for Applied Linguistics and Delta Systems. ISBN 1887744029
  • Parrish, T.; Perez, M; Merickel, A.; and Linquanti, R.(2006). "Effects of the Implementation of Proposition 227 on the Education of English Learners, K-12, Findings from a Five-Year Evaluation: Final Report." Washington, DC: AIR and San Francisco: WestEd. The complete report is available free at [19]. An abbreviated, more accessible summary of the findings is available at [20]

External links


Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.