1.  Peer Reviewed Title: Universal voluntary HIV testing and immediate antiretroviral therapy [letter] Author: Assefa Y; Lera M Source: Lancet. 2009 Mar 28;373(9669):1080; author reply 1080-1. Abstract: Reuben Granich and colleagues use mathematical models to show that annual screening of most adults for HIV, with immediate commencement of antiretroviral therapy for all infected, would strikingly reduce HIV incidence. The findings are very interesting. We would like to share our lessons from Ethiopia. Ethiopia had a millennium AIDS campaign with the objective of increasing the number of people tested for HIV through universal voluntary counselling and testing and providing antiretroviral treatment for eligible patients. We were able to increase the number of people tested in 1 year from 560 000 in 2005/06 to 4.6 million in 2007/08. The number of patients started on antiretroviral therapy per month increased from 3500 to more than 5700. Even though we accomplished a lot in terms of HIV testing and antiretroviral therapy provision, we had challenges during the rapid scale-up of these services. We learnt that mass testing is very resource-intensive and needs a strong health system, including adequate human resources and a continuous supply of commodities. As a result, our current guiding principle is "high yield" and "high impact" through targeted testing of most-at-risk populations: patients with tuberculosis or sexually transmitted diseases, and pregnant women. Universal voluntary HIV testing and antiretroviral therapy provision might be effective in reducing HIV transmission, but with the current health system constraints in many sub-Saharan African countries such as Ethiopia, it is really not feasible to practise it. We recommend "high yield" and "high impact" HIV testing with early initiation of antiretroviral therapy, and improved adherence and retention of patients in care and treatment. (full-text) Language: English Keywords: DEVELOPING COUNTRIES | THEORETICAL STUDIES | RESEARCH PROPOSAL | THEORETICAL MODELS | COST BENEFIT ANALYSIS | PERSONS LIVING WITH HIV/AIDS | ANTIRETROVIRAL THERAPY | BEST PRACTICES | HIV PREVENTION | PUBLIC HEALTH | TIME FACTORS | COST EFFECTIVENESS | ETHICS | NOTIFICATION | Studies | Research Methodology | Quantitative Evaluation | Evaluation | HIV Infections | Viral Diseases | Diseases | HIV | Programs | Organization and Administration | Health | Population Dynamics | Demographic Factors | Population | Evaluation Indexes | Sociocultural Factors | Political Factors Document Number: 330977 |
| 2. Title: The unique characteristics of ovarian carcinogenesis in the adolescent and young adult population. Author: Gibbon DG; Diaz-Arrastia C Source: Seminars In Oncology. 2009 Jun;36(3):250-7. Abstract: Ovarian cancer in the adolescent and young adult (AYA) population is a disease that is distinctly different with regard to risk factors, genetics, and pathology when compared to ovarian cancers occurring in older women. This article will review the theories behind ovarian carcinogenesis and attempt to elucidate why these tumors exhibit their unique biologic characteristics. Knowledge of these differences will allow us to begin to develop strategies for future research endeavors enabling improved survival in AYA women diagnosed with ovarian cancer. Language: English Keywords: UNITED STATES OF AMERICA | THEORETICAL STUDIES | CLASSIFICATION | ADOLESCENTS, FEMALE | WOMEN | OVARIAN CANCER | AGE FACTORS | GENETICS | NEOPLASMS | OVARIECTOMY | FERTILITY | Developed Countries | North America | Americas | Studies | Research Methodology | Adolescents | Youth | Population Characteristics | Demographic Factors | Population | Cancer | Diseases | Biology | Gynecologic Surgery | Urogenital Surgery | Surgery | Treatment | Medical Procedures | Medicine | Health Services | Delivery of Health Care | Health | Population Dynamics Document Number: 342163 |
| 3. Title: Individual versus household migration decision rules: gender and marital status differences in intentions to migrate in South Africa. Author: Gubhaju B; De Jong GF Source: International Migration. 2009 Jun;47(1):31-61. Abstract: This research tests the thesis that the neoclassical microeconomic and the new household economic theoretical assumptions on migration decision-making rules are segmented by gender, marital status, and time frame of intention to migrate. Comparative tests of both theories within the same study design are relatively rare. Utilizing data from the Causes of Migration in South Africa national migration survey, we analyse how individually held "own-future" versus alternative "household well-being" migration decision rules effect the intentions to migrate of male and female adults in South Africa. Results from the gender and marital status specific logistic regressions models show consistent support for the different gender-marital status decision rule thesis. Specifically, the "maximizing one's own future" neoclassical microeconomic theory proposition is more applicable for never married men and women, the "maximizing household income" proposition for married men with short-term migration intentions, and the "reduce household risk" proposition for longer time horizon migration intentions of married men and women. Results provide new evidence on the way household strategies and individual goals jointly affect intentions to move or stay. Language: English Keywords: SOUTH AFRICA | THEORETICAL STUDIES | SURVEYS | EVER MARRIED | NEVER MARRIED | MIGRATION | MOTIVATION | GENDER ISSUES | MARITAL STATUS | DECISION MAKING | ECONOMIC FACTORS | Developing Countries | Africa, Southern | Africa, Sub Saharan | Africa | Studies | Research Methodology | Sampling Studies | Nuptiality | Demographic Factors | Population | Population Dynamics | Psychological Factors | Behavior | Sociocultural Factors Document Number: 341299 |
| 4. Title: Theory-based interventions for contraception. Author: Lopez LM; Tolley EE; Grimes DA; Chen-Mok M Source: Cochrane Database of Systematic Reviews. 2009;(1):CD007249. Abstract: BACKGROUND: The explicit use of theory in research helps expand the knowledge base. Theories and models have been used extensively in HIV-prevention research and in interventions for preventing sexually transmitted infections (STIs). The health behavior field uses many theories or models of change. However, educational interventions addressing contraception often have no stated theoretical base. OBJECTIVES: Review randomized controlled trials that tested a theoretical approach to inform contraceptive choice; encourage contraceptive use; or promote adherence to, or continuation of, a contraceptive regimen. SEARCH STRATEGY: We searched computerized databases for trials that tested a theory-based intervention for improving contraceptive use (MEDLINE, POPLINE, CENTRAL, PsycINFO, EMBASE, ClinicalTrials.gov, and ICTRP). We also wrote to researchers to find other trials. SELECTION CRITERIA: Trials tested a theory-based intervention for improving contraceptive use. We excluded trials focused on high-risk groups. Interventions addressed the use of one or more contraceptive methods. The reports provided evidence that the intervention was based on a specific theory or model. The primary outcomes were pregnancy, contraceptive choice, initiating or changing contraceptive use, contraceptive regimen adherence, and contraception continuation. DATA COLLECTION AND ANALYSIS: The primary author evaluated abstracts for eligibility. Two authors extracted data from included studies. We calculated the odds ratio for dichotomous outcomes and the mean difference for continuous data. No meta-analysis was conducted due to intervention differences. MAIN RESULTS: Of 26 trials, 12 interventions addressed contraception (other than condoms), while 14 focused on condom use for preventing HIV or STIs. In 2 of 10 trials with pregnancy or birth data, a theory-based group showed better results. Four of nine trials with contraceptive use (other than condoms) showed better outcomes in an experimental group. For condom use, a theory-based group had favorable results in 14 of 20 trials, but the number was halved in a subgroup analysis. Social Cognitive Theory was the main theoretical basis for 12 trials, and 10 showed positive results. Of the other 14 trials, favorable results were shown for other social cognition models (N=2), motivational interviewing (N=5), and the AIDS Risk Reduction Model (N=2). No major patterns were detected by type of theory, intervention, or target population. AUTHORS' CONCLUSIONS: Family planning researchers and practitioners could apply the relevant theories and effective interventions from HIV and STI prevention. More thorough use of single theories would help inform the field about what works. Better reporting is needed on research design and intervention implementation. Language: English Keywords: UNITED STATES OF AMERICA | METHODOLOGICAL STUDIES | THEORETICAL STUDIES | LITERATURE REVIEW | THEORETICAL MODELS | CLINICAL TRIALS | WOMEN | CONTRACEPTIVE METHODS CHOSEN | CONDOM USE | CONTRACEPTIVE USAGE | MOTIVATION | COUNSELING | HIV PREVENTION | Developed Countries | North America | Americas | Research Methodology | Clinical Research | Demographic Factors | Population | Contraception | Family Planning | Risk Reduction Behavior | Behavior | Psychological Factors | Clinic Activities | Program Activities | Programs | Organization and Administration | HIV Infections | Viral Diseases | Diseases Document Number: 329594 |
| 5. Peer Reviewed Title: Theory-based strategies for improving contraceptive use: a systematic review. Author: Lopez LM; Tolley EE; Grimes DA; Chen-Mok M Source: Contraception. 2009 Jun;79(6):411-7. Abstract: BACKGROUND: Theories and models help explain how behavior change occurs. We systematically reviewed randomized controlled trials that examined theory-based interventions for improving contraceptive use. STUDY DESIGN: We searched electronic databases for eligible trials. Primary outcomes included pregnancy and contraceptive use. We calculated the odds ratio for dichotomous outcomes and the mean difference for continuous data. RESULTS: Of 14 included trials, 10 showed positive results for a theory-based group: 2 of 10 studies with pregnancy or birth data, 4 of 9 addressing contraceptive use (for contraception) and 5 of 9 with condom use (to prevent HIV/sexually transmitted infections). An experimental group had favorable results for six of seven trials based on Social Cognitive Theory, two based on other social cognition models and two using motivational interviewing. Most interventions focused on adolescents and involved multiple sessions. CONCLUSIONS: Effects were not consistent across outcomes and comparisons. The field could benefit from thorough use of single theories and better reporting on intervention implementation. Language: English Keywords: UNITED STATES OF AMERICA | LITERATURE REVIEW | THEORETICAL STUDIES | CASE CONTROL STUDIES | KAP SURVEYS | THEORETICAL MODELS | WOMEN | ADOLESCENTS | CONTRACEPTIVE USAGE | CONDOM USE | CONTRACEPTIVE EFFECTIVENESS | SEXUALLY TRANSMITTED DISEASE PREVENTION | MOTIVATION | TIME FACTORS | PROGRAM DESIGN | Developed Countries | North America | Americas | Studies | Research Methodology | Surveys | Sampling Studies | Demographic Factors | Population | Youth | Age Factors | Population Characteristics | Contraception | Family Planning | Risk Reduction Behavior | Behavior | Sexually Transmitted Diseases | Reproductive Tract Infections | Infections | Diseases | Psychological Factors | Population Dynamics | Programs | Organization and Administration Document Number: 341105 |
| 6. Title: The role of sexually abstained groups in two-sex demographic and epidemic logistic models with non-linear mortality. Author: Maxin D; Milner FA Source: Journal of Theoretical Biology. 2009 Jun 7;258(3):389-402. Abstract: We describe several gender structured population models governed by logistic growth with non-linear death rate. We extend these models to include groups of people isolated from sexual activity and individuals exposed to a mild and long-lasting sexually transmitted disease, i.e. without disease-induced mortality and recovery. The transmission of the disease is modeled through formation/separation of heterosexual couples assuming that one infected individual automatically infects his/her partner. We are interested in how the non-reproductive class may change the demographic tendencies in the general population and whether they can curb the growth of the infected group while keeping the healthy one at acceptable levels. A comparison of the equilibrium total population size in the presence and the absence of the isolated class is also provided. Language: English Keywords: GLOBAL | THEORETICAL STUDIES | MATHEMATICAL MODEL | EPIDEMIOLOGY | SEXUALLY TRANSMITTED DISEASES | TRANSMISSION | ABSTINENCE | REPRODUCTIVE BEHAVIOR | MARRIAGE | POPULATION DYNAMICS | Studies | Research Methodology | Theoretical Models | Public Health | Health | Reproductive Tract Infections | Infections | Diseases | Family Planning, Behavioral Methods | Family Planning | Fertility | Demographic Factors | Population | Nuptiality Document Number: 342385 |
| 7. Peer Reviewed Title: HIV / AIDS and hope(lessness). Author: Barnett T Source: Global Public Health. 2008 Jul;3(3):233-248. Abstract: Public policy debates, about HIV and prevention policy, have tended to occupy positions at the extremes of the two camps of rational choice, theorists and structuralists. This paper argues that the concept of hope may offer a way through this policy and paradigmatic log-jam. Hope is an individually measurable concept, which serves to link the ecological concept of risk environment with that of individual choice. It may be extended into broader understandings of the social epidemiology of infectious diseases. Use of an operationalised concept of hope also offers a possible way forward for rapid community diagnosis and participation in policy development, because it is immediately and intuitively accessible at three often separated levels: the individual actor, the researcher and those acting in the policy arena. (author's) Language: English Keywords: THEORETICAL STUDIES | EVALUATION | POLICYMAKERS | HIV PREVENTION | HEALTH POLICY | ATTITUDES | ABSTINENCE, BE FAITHFUL, CONDOM USE | ECOLOGY | RISK ASSESSMENT | EPIDEMIOLOGY | SOCIOLOGY | COMMUNITY HEALTH SERVICES | HIV TESTING | COMMUNITY PARTICIPATION | Administrative Personnel | Organization and Administration | HIV Infections | Viral Diseases | Diseases | Policy | Political Factors | Sociocultural Factors | Psychological Factors | Behavior | Sex Behavior | Environment | Public Health | Health | Social Sciences | Science | Primary Health Care | Health Services | Delivery of Health Care | Laboratory Examinations and Diagnoses | Examinations and Diagnoses | Medical Procedures | Medicine Document Number: 327756 |
8.  Peer Reviewed Title: Perturbation analysis of nonlinear matrix population models. Author: Caswell H Source: Demographic Research. 2008 Mar;18(3):59-116. Abstract: Perturbation analysis examines the response of a model to changes in its parameters. It is commonly applied to population growth rates calculated from linear models, but there has been no general approach to the analysis of nonlinear models. Nonlinearities in demographic models may arise due to density-dependence, frequency-dependence (in 2-sex models), feedback through the environment or the economy, and recruitment subsidy due to immigration, or from the scaling inherent in calculations of proportional population structure. This paper uses matrix calculus to derive the sensitivity and elasticity of equilibria, cycles, ratios (e.g., dependency ratios), age averages and variances, temporal averages and variances, life expectancies, and population growth rates, for both age-classified and stage-classified models. Examples are presented, applying the results to both human and non-human populations. (author's) Language: English Keywords: MASSACHUSETTS | METHODOLOGICAL STUDIES | THEORETICAL STUDIES | MATHEMATICAL MODEL | DEMOGRAPHIC ANALYSIS | POPULATION | POPULATION THEORY | POPULATION GROWTH ESTIMATION | ENVIRONMENT | MACROECONOMIC FACTORS | AGE FACTORS | TIME FACTORS | LIFE EXPECTANCY | Developed Countries | United States of America | North America | Americas | Theoretical Models | Research Methodology | Demography | Social Sciences | Science | Sociocultural Factors | Estimation Techniques | Economic Factors | Population Characteristics | Demographic Factors | Population Dynamics | Length of Life | Mortality Document Number: 325250 |
| 9. Title: On the contribution of sectoral natural population growth to the aggregate poverty change. Author: Chatti R; El Lahga A Source: Journal of Population Economics. 2008 Jan;21(1):183-190. Abstract: This note extends the Ravallion and Huppi aggregate poverty change decomposition to account for the distinct contribution of migration and differential natural population growth between sectors to the aggregate poverty change. We apply our decomposition to three Least Developing countries. We find that accounting for sectoral difference in natural population growth has a considerable impact on national poverty change. (author's) Language: English Keywords: DEVELOPING COUNTRIES | RESEARCH REPORT | THEORETICAL STUDIES | MATHEMATICAL MODEL | ECONOMIC MODEL | MIGRANTS | POPULATION | MIGRATION | POVERTY | POPULATION GROWTH | LABOR MIGRATION | Theoretical Models | Research Methodology | Population Dynamics | Demographic Factors | Socioeconomic Factors | Economic Factors Document Number: 322761 |
| 10. Peer Reviewed Title: A theory-based approach to understanding condom errors and problems reported by men attending an STI clinic. Author: Crosby RA; Salazar LF; Yarber WL; Sanders SA; Graham CA Source: AIDS and Behavior. 2008 May;12(3):412-418. Abstract: We employed the information-motivation-behavioral skills (IMB) model to guide an investigation of correlates for correct condom use among 278 adult (18-35 years old) male clients attending a sexually transmitted infection (STI) clinic. An anonymous questionnaire aided by a CD-recording of the questions was administered. Linear Structural Relations Program was used to conduct path analyses of the hypothesized IMB model. Parameter estimates showed that while information did not directly affect behavioral skills, it did have a direct (negative) effect on condom use errors. Motivation had a significant direct (positive) effect on behavioral skills and a significant indirect (positive) effect on condom use errors through behavioral skills. Behavioral skills had a direct (negative) effect on condom use errors. Among men attending a public STI clinic, these findings suggest brief, clinic-based, safer sex programs for men who have sex with women should incorporate activities to convey correct condom use information, instill motivation to use condoms correctly, and directly enhance men's behavioral skills for correct use of condoms. (author's) Language: English Keywords: UNITED STATES OF AMERICA | THEORETICAL STUDIES | RESEARCH REPORT | THEORETICAL MODELS | KAP SURVEYS | MEN | URBAN POPULATION | CONDOM FAILURE | THEORETICAL EFFECTIVENESS | MOTIVATION | KNOWLEDGE | INFORMATION | SEX EDUCATION | SAFER SEX | CONDOM USE | Developed Countries | North America | Americas | Research Methodology | Surveys | Sampling Studies | Studies | Demographic Factors | Population | Population Characteristics | Condoms | Barrier Methods | Contraceptive Methods | Contraception | Family Planning | Contraceptive Effectiveness | Psychological Factors | Behavior | Sociocultural Factors | Education | Sex Behavior | Risk Reduction Behavior Document Number: 325898 |
| 11. Peer Reviewed Title: The limits of behaviour change theory: Condom use and contexts of HIV risk in the Kolkata sex industry. Author: Evans C; Lambert H Source: Culture, Health and Sexuality. 2008 Jan;10(1):27-41. Abstract: This paper uses ethnographic data from a sex workers' HIV project in India to consider the appropriateness of individual, social/group and structural theories of health behaviour when applied to HIV-prevention initiatives. Existing theories are critiqued for their modernist representation of behaviour as determined by individual rational decision-making processes or by external structural forces, with inadequate recognition being given to the roles that human agency, subjective meaning and local context play in everyday actions. Analysis of sex workers' accounts of their sexual practices suggests that existing theories of health behaviour can only partially account for sexual behaviour change retrospectively and that they have limited predictive value with respect to the outcomes of individual sexual encounters. Our data show that these outcomes were, in fact, highly context dependent, while possibilities for action were ultimately strongly constrained by structural forces. Findings suggest that interventions need to adopt an integrated, structurally-oriented approach for promoting safer sexual practices in sex work settings. Recognising that no one model of health behaviour is likely to be adequate in explaining or predicting behaviour change encourages responsiveness to local people's agency, recognises the different (health- and non-health-related) registers of risk with which people operate and encourages flexibility according to local contingencies and contexts. (author's) Language: English Keywords: INDIA | RESEARCH REPORT | THEORETICAL STUDIES | KAP SURVEYS | SEX WORKERS | WOMEN IN DEVELOPMENT | BEHAVIOR CHANGE COMMUNICATION | CONDOM USE | HIV TRANSMISSION | RISK ASSESSMENT | DECISION MAKING | SEX BEHAVIOR | SAFER SEX | RISK BEHAVIOR | Developing Countries | Asia, Southern | Asia | Surveys | Sampling Studies | Studies | Research Methodology | Behavior | Economic Development | Economic Factors | Communication Programs | Communication | Behavior Change | Risk Reduction Behavior | HIV Infections | Viral Diseases | Diseases | Evaluation Document Number: 313969 |
| 12. Title: Cognitive dissonance as an explanation of the genesis, evolution and persistence of Thabo Mbeki’s HIV denialism. Author: Kenyon C Source: African Journal of AIDS Research. 2008 May;7(1):29-35. Abstract: The ongoing damage that the newer forms of HIV denialism are visiting upon our country is evidenced by the recent firing of Nozizwe Madlala-Routledge, the South African Deputy Minister of Health. It is widely believed that the underlying reason for her dismissal was her support of orthodox HIV treatment and prevention strategies and her disdain for HIV denialism. This paper seeks to understand the origins, spread and metamorphosis of President Thabo Mbeki's HIV denialism in South Africa. Using the theory of cognitive dissonance, I argue that, given the structural beliefs of the African National Congress (ANC) and the pattern of emergence of HIV in the 1980s, a degree of scepticism around the putative science of HIV was probable in ANC circles. On assuming the Presidency in 1999, Mbeki tapped into this scepticism to formulate his initial biological version of HIV denialism, which claimed that 'a virus can't cause a syndrome.' The steady erosion of support for this flagrant HIV denialism, together with the rise of neoliberal thinking in the ANC, would lead to the evolution of this biological denialism into a form of treatment denialism. This ideology argued against the widespread provision and use of antiretroviral treatment. Empirical evidence is presented to demonstrate the extent to which ongoing HIV denial in the general population is continuing to fuel the spread of HIV. (author's) Language: English Keywords: SOUTH AFRICA | RESEARCH REPORT | THEORETICAL STUDIES | INFLUENTIALS | HIV | AIDS | POLICY | POLITICAL FACTORS | LIBERALISM | ANTIRETROVIRAL THERAPY | TREATMENT | Africa, Southern | Africa, Sub Saharan | Africa | Developing Countries | Knowledge Sources | Communication | HIV Infections | Viral Diseases | Diseases | Sociocultural Factors | Medical Procedures | Medicine | Health Services | Delivery of Health Care | Health Document Number: 327158 |
| 13. Title: A developmental psychopathology framework of the psychosocial needs of children orphaned by HIV. Author: Li X; Naar-King S; Barnett D; Stanton B; Fang X Source: Journal of the Association of Nurses in AIDS Care. 2008 Mar-Apr;19(2):147-157. Abstract: In addition to the obstacles to a successful resolution of grief normally faced by children whose parents have died, children orphaned by AIDS may face additional psychological and social challenges. However, limited attention has been paid to psychosocial and developmental needs of children orphaned by HIV/AIDS, particularly in resource-poor countries or regions. In this article the authors review the global literature on child bereavement and AIDS orphan care experiences in developing countries and present a developmental psychopathology model of the psychosocial issues facing AIDS orphans. The authors identify gaps in the literature and provide suggestions for future research on AIDS orphans in resource-poor countries and regions. They emphasize that future studies need to assess the status of behaviors and mental health of children orphaned by AIDS within a developmental framework, identify those individual and social factors associated with grief, and examine the long-term impact of quality of care, developmental maturation, and attachment with caregivers on the psychosocial well-being of AIDS orphans. (author's) Language: English Keywords: DEVELOPING COUNTRIES | LITERATURE REVIEW | THEORETICAL STUDIES | THEORETICAL MODELS | CHILDREN | ORPHANS AND VULNERABLE CHILDREN | HIV INFECTIONS | AIDS | PSYCHOSOCIAL FACTORS | SOCIAL ADJUSTMENT | CHILD DEVELOPMENT | MENTAL HEALTH | DEATH | Research Methodology | Youth | Age Factors | Population Characteristics | Demographic Factors | Population | Family and Household | Sociocultural Factors | Viral Diseases | Diseases | Behavior | Social Behavior | Biology | Health | Mortality | Population Dynamics Document Number: 325228 |
| 14. Title: "Backslanted X" fertility dynamics and macroeconomics. Author: Maoz YD Source: Journal of Population Economics. 2008 Jan;21(1):159-172. Abstract: A large number of pairs of countries exhibit a dynamic pattern in which: (1) Fertility in both countries declines across time; (2) initially, one country has a higher fertility and a lower per-capita income than the other; and (3) in time, as percapita incomes converge, fertility rates in the poorer country become lower than in the richer one. This article documents the prevalence of such dynamics and offers a theoretical model in which these dynamics emerge endogenously. Assuming differences in the degree of utility substitution between consumption and rearing children across countries generates all three components of these dynamics. (author's) Language: English Keywords: GLOBAL | THEORETICAL STUDIES | RESEARCH REPORT | CROSS-CULTURAL COMPARISONS | THEORETICAL MODELS | MATHEMATICAL MODEL | POPULATION | MACROECONOMIC FACTORS | FERTILITY RATE | INCOME | HOUSEHOLD CONSUMPTION | Comparative Studies | Studies | Research Methodology | Economic Factors | Birth Rate | Fertility Measurements | Fertility | Population Dynamics | Demographic Factors | Socioeconomic Factors | Microeconomic Factors Document Number: 322760 |
| 15. Title: Tackling poverty-migration linkages: Evidence from Ghana and Egypt. Author: Sabates-Wheeler R; Sabates R; Castaldo A Source: Social Indicators Research. 2008 Jun;87(2):307-328. Abstract: Are migrants able to use the migration experience to their benefit, that is to improve their livelihoods, and is this result nuanced by whether migrants are poor or nonpoor? This paper explores these questions quantitatively using data on migrants and nonmigrants from Ghana and Egypt. It describes the main challenges in the empirical literature and introduces a conceptual model to explore the links between migration and poverty. The empirical model accounts for the direct effects of migration on poverty and for the role of migration in moderating the dynamics of poverty. Results show the selectivity of migration with respect to subjective poverty and that migration can have a significant impact on helping people improve their livelihoods. The paper further finds that selectivity with respect to human capital depends on 'reasons for migration' and visa status. These findings enrich existing empirical studies by providing a clear estimation of sequential events and enable policymakers to better understand the processes behind migration and poverty. (author's) Language: English Keywords: GHANA | EGYPT | THEORETICAL STUDIES | LITERATURE REVIEW | THEORETICAL MODELS | MIGRANTS | INTERNATIONAL MIGRATION | POVERTY | ECONOMIC FACTORS | Developing Countries | Africa, Western | Africa, Sub Saharan | Africa | Africa, North | Research Methodology | Migration | Population Dynamics | Demographic Factors | Population | Socioeconomic Factors Document Number: 326456 |
| 16. Title: Blacks and the family cap: Pregnancy, abortion, and spillovers. Author: Sabia JJ Source: Journal of Population Economics. 2008 Jan;21(1):111-134. Abstract: While reducing out-of-wedlock childbearing is a central goal of welfare reform, most policymakers prefer achieving this objective via a reduction in nonmarital pregnancy rates rather than through an increase in the incidence of abortion. Using aggregate state-level data from 1984 to 1998, I estimate fixed effects models that allow for autocorrelated and heteroskedastic disturbances to examine the association between the family cap and nonmarital birth, pregnancy, and abortion rates. I find robust evidence that the family cap is associated with a reduction in nonmarital birth rates, particularly among black women. This reduction is driven by a reduction in nonmarital pregnancy rates rather than through an increase in abortion or marriage rates. These findings suggest that that the stigmatizing effect of the family cap may influence the nonmarital pregnancy decisions of black women. (author's) Language: English Keywords: UNITED STATES OF AMERICA | RESEARCH REPORT | THEORETICAL STUDIES | LONGITUDINAL STUDIES | MATHEMATICAL MODEL | BLACKS | PREMARITAL PREGNANCY | FAMILY SIZE, COMPLETED | ABORTION RATE | BIRTH RATE | STIGMA | PUBLIC ASSISTANCE | DISINCENTIVES | Developed Countries | North America | Americas | Studies | Research Methodology | Theoretical Models | Ethnic Groups | Cultural Background | Population Characteristics | Demographic Factors | Population | Reproductive Behavior | Fertility | Population Dynamics | Family Size | Family Characteristics | Family and Household | Sociocultural Factors | Fertility Control, Postconception | Family Planning | Fertility Measurements | Social Problems | Government Financing | Financial Activities | Economic Factors | Policy | Political Factors Document Number: 322758 Notification |
| 17. Peer Reviewed Title: Health work, female sex workers and HIV / AIDS: Global and local dimensions of stigma and deviance as barriers to effective interventions. Author: Scambler G; Paoli F Source: Social Science and Medicine. 2008 Apr;66(8):1848-1862. Abstract: This paper addresses the near global attribution of stigma and deviance to female sex workers, and the salience of this attribution for health interventions in HIV/AIDS. A conceptual frame is developed as a guide to comparative sociological study in this area, and the importance of explanation at the level of social structure emphasized. After a general review of the empirical literature, more sustained attention is paid to specific aspects of female sex work in three contexts or figurations, the cities of London, Bangkok and Kolkarta. It is argued that norms of shame and blame and the labelling process with which they are bound up always arise within a structure nexus. We emphasis, in particular, the figuration-specific tensions between the global and the local, system and lifeworld and, the relationship between structure, agency and culture. The article concludes with a discussion of attempts to empower female sex workers and with a series of five orienting themes comprising a research programmefor the future. (author's) Language: English Keywords: UNITED KINGDOM | THAILAND | INDIA | THEORETICAL STUDIES | SEX WORKERS | WOMEN | STIGMA | HIV PREVENTION | AIDS | INTERVENTIONS | CULTURE | Developed Countries | Europe, Western | Europe | Asia, Southeastern | Asia | Developing Countries | Asia, Southern | Sex Behavior | Behavior | Demographic Factors | Population | Social Problems | Sociocultural Factors | HIV Infections | Viral Diseases | Diseases | Programs | Organization and Administration Document Number: 325442 |
| 18. Peer Reviewed Title: Potential impacts of iron biofortification in India. Author: Stein AJ; Meenakshi JV; Qaim M; Nestel P; Sachdev HP Source: Social Science and Medicine. 2008 Apr;66(8):1797-1808. Abstract: Iron deficiency is a widespread nutrition and health problem in developing countries, causing impairments in physical activity and cognitive development, as well as maternal mortality. Although food fortification and supplementation programmes have been effective in some countries, their overall success remains limited. Biofortification, that is, breeding food crops for higher micronutrient content, is a relatively new approach, which has been gaining international attention recently. We propose a methodology for ex ante impact assessment of iron biofortification, building on a disability-adjusted life years (DALYs) framework. This methodology is applied in an Indian context. Using a large and representative data set of household food consumption, the likely effects of iron-rich rice and wheat varieties are simulated for different target groups and regions. These varieties, which are being developed by an international public research consortium, based on conventional breeding techniques, might beready for local distribution within the next couple of years. The results indicate sizeable potential health benefits. Depending on the underlying assumptions, the disease burden associated with iron deficiency could be reduced by 19-58%. Due to the relatively low institutional cost to reach the target population, the expected cost-effectiveness of iron biofortification compares favourably with other micronutrient interventions. Nonetheless, biofortification should not be seen as a substitute for other interventions. Each approach has its particular strengths, so they complement one another. (author's) Language: English Keywords: INDIA | THEORETICAL STUDIES | METHODOLOGICAL STUDIES | THEORETICAL MODELS | IRON | DEFICIENCY DISEASES | FOOD SUPPLEMENTATION | FOOD SUPPLY | NUTRITION | AGRICULTURE | COST EFFECTIVENESS | INTERVENTIONS | Developing Countries | Asia, Southern | Asia | Research Methodology | Metals | Vitamins and Minerals | Physiology | Biology | Nutrition Disorders | Diseases | Nutrition Programs | Primary Health Care | Health Services | Delivery of Health Care | Health | Natural Resources | Environment | Macroeconomic Factors | Economic Factors | Evaluation Indexes | Quantitative Evaluation | Evaluation | Programs | Organization and Administration Document Number: 325441 |
| 19. Title: Social aspirations and choice of fertility: Why can status motive reduce per-capita growth? Author: Tournemaine F Source: Journal of Population Economics. 2008 Jan;21(1):49-66. Abstract: To examine the relationship between social aspirations, fertility choices and growth performances, we develop a R&D-based model in which individuals care about the number of children they bring up and their social status. In such an economy, we find that stronger status motives have a negative effect on growth. The reason is that individuals bring up fewer children, as children are an obstacle to the achievement of their social status. Introducing an endogenous choice of quality for children, we show that stronger status motives lead individuals to bring up fewer but higher quality children. In this case, social aspirations heighten the desire of parents to substitute the quantity for the quality of children because education of children fosters society's productive ability, indirectly improving parents' social status. (author's) Language: English Keywords: THAILAND | THEORETICAL STUDIES | MATHEMATICAL MODEL | ECONOMIC MODEL | PARENTS | ASPIRATIONS | HUMAN CAPITAL | FERTILITY PREFERENCES | ECONOMIC DEVELOPMENT | SOCIAL CLASS | SOCIOECONOMIC STATUS | FAMILY SIZE, DESIRED | QUALITY OF LIFE | MOTIVATION | EDUCATION | Asia, Southeastern | Asia | Developing Countries | Theoretical Models | Research Methodology | Family Relationships | Family Characteristics | Family and Household | Sociocultural Factors | Psychological Factors | Behavior | Human Resources | Economic Factors | Fertility | Population Dynamics | Demographic Factors | Population | Socioeconomic Factors | Family Size | Social Welfare Document Number: 322755 |
| 20. Peer Reviewed Title: Estimation of a structural model of the determinants of neonatal mortality in Hungary, 1984 - 88 and 1994 - 98. Author: Vandresse M Source: Population Studies. 2008 Mar;62(1):85-11. Abstract: We developed and evaluated a structural model of the determinants of neonatal mortality in Hungary that embodies the causal mechanisms by which its proximate and indirect determinants - socio-economic, behavioural, and biological - are related. The statistical model used distinguishes between endogenous and exogenous variables and allows the causal effect of each to be correctly estimated. Unobserved variables are integrated into the model, which was tested using Hungarian data for the periods 1984-88 and 1994-98. The principal findings are as follows: weight at birth and duration of gestation are the most important of the (direct) causal determinants of neonatal mortality. Mother's age has an indirect and detrimental effect: when mothers are older than 30 years of age, the risk of lower birth weight or multiple births and, in consequence, neonatal mortality is increased. Father's age has no direct or indirect causal effect on neonatal mortality. (author's) Language: English Keywords: HUNGARY | THEORETICAL STUDIES | THEORETICAL MODELS | INFANT | NEONATAL MORTALITY | MORTALITY DETERMINANTS | ESTIMATION TECHNIQUES | RISK FACTORS | MATERNAL AGE | PATERNAL AGE | BIRTH WEIGHT | GESTATIONAL AGE | Developing Countries | Europe, Central | Europe | Research Methodology | Youth | Age Factors | Population Characteristics | Demographic Factors | Population | Infant Mortality | Mortality | Population Dynamics | Biology | Parental Age | Body Weight | Physiology | Fetus | Pregnancy | Reproduction Document Number: 324675 |
| 21. Peer Reviewed Title: Review of corruption in the health sector: Theory, methods and interventions. Author: Vian T Source: Health Policy and Planning. 2008;23(2):83-94. Abstract: There is increasing interest among health policymakers, planners and donors in how corruption affects health care access and outcomes, and what can be done to combat corruption in the health sector. Efforts to explain the risk of abuse of entrusted power for private gain have examined the links between corruption and various aspects of management, financing and governance. Behavioural scientists and anthropologists also point to individual and social characteristics which influence the behaviour of government agents and clients. This article presents a comprehensive framework and a set of methodologies for describing and measuring how opportunities, pressures and rationalizations influence corruption in the health sector. The article discusses implications for intervention, and presents examples of how theory has been applied in research and practice. Challenges of tailoring anti-corruption strategies to particular contexts, and future directions for research, are addressed. (author's) Language: English Keywords: DEVELOPING COUNTRIES | THEORETICAL STUDIES | LITERATURE REVIEW | HEALTH PERSONNEL | POLICYMAKERS | GOVERNMENT OFFICIALS | HEALTH SERVICES ADMINISTRATION | MANAGEMENT | CRIME | PUBLIC SECTOR | INTERVENTIONS | Delivery of Health Care | Health | Administrative Personnel | Organization and Administration | Social Problems | Sociocultural Factors | Macroeconomic Factors | Economic Factors | Programs Document Number: 324663 |
| 22. Title: Risk amplification: HIV in migrant communities. Author: Banati P Source: Development Southern Africa. 2007 Mar;24(1):205-223. Abstract: The demography of both urban and rural South Africa is shaped by migration, with three unique patterns: labour-sending, labour-receiving and rural areas. This article explores the relationship between HIV risk and migration in South Africa. It identifies the urban informal settlements common in labour-receiving areas as key magnifiers of HIV risk, increasing the vulnerability of migrant workers in these townships. It examines the urban informal settlement, a unique social environment with distinctly high-risk behaviour dynamics, as a focal determinant of HIV. It proposes this framework as an extension of the migration-HIV dialectic beyond the traditionally unidimensional approach, to encompass a more contextualised discussion. This methodology, which uses the environment as an entry point to understanding behaviour and emphasises the importance of addressing the HIV-migration issue within a broader development perspective, has important implications for HIV programming in South Africa. (author's) Language: English Keywords: SOUTH AFRICA | LITERATURE REVIEW | THEORETICAL STUDIES | MIGRANT WORKERS | HIV INFECTIONS | AIDS | RISK FACTORS | URBAN AREAS | RURAL AREAS | SOCIAL ADJUSTMENT | Africa, Southern | Africa, Sub Saharan | Africa | Developing Countries | Labor Force | Human Resources | Economic Factors | Viral Diseases | Diseases | Biology | Geographic Factors | Population | Social Behavior | Behavior Document Number: 326676 |
| 23. Title: AIDS: Public justice and private meaning. Author: Boshoff A Source: Tydskrif vir die Suid-Afrikaanse Reg. 2007;(2):339-345. Abstract: A theoretical discussion of the AIDS pandemic in South Africa is best done against the background of a straight-forward statistical analysis. The facts, simple and stark, speak for themselves: at the moment South Africa has the highest number of people living with HIV in the world. A government survey, conducted in October 2005, estimates that 5.5 million South Africans are living with the virus, accounting for more than one-eighth of the estimated cases worldwide. UNAIDS estimates that nearly 19 percent of people aged 15 to 49 in South Africa are HIV positive. Around 1.5 million South Africans have died from AIDS-related illnesses since the start of the epidemic. The annual number of new HIV infections is close to half a million (around 800 per day) and is likely to remain that high over the next few years. When one turns to the statistics pertaining to the most vulnerable groups it gets no better: the highest prevalence and incidence of HIV is found amongst pregnant women and women of child-bearing age, with 30.2 percent of antenatal clinic attendees testing HIV positive. Medically, the greatest risk of being infected with HIV is towards the end of pregnancy and a startling 5.3 percent of children between 2 and 4 are HIV positive due to mother-to-child transmission. (excerpt) Language: English Keywords: SOUTH AFRICA | THEORETICAL STUDIES | PHILOSOPHICAL OVERVIEW | THEORETICAL MODELS | RELIGIOUS ASPECTS | PERSONS LIVING WITH HIV/AIDS | PRISONERS | COURT DECISION | ANTIRETROVIRAL THERAPY | DEATH | PAIN | Africa, Southern | Africa, Sub Saharan | Africa | Developing Countries | Research Methodology | Religion | Sociocultural Factors | HIV Infections | Viral Diseases | Diseases | Crime | Social Problems | Litigation | Political Factors | HIV | Mortality | Population Dynamics | Demographic Factors | Population | Signs and Symptoms Document Number: 318188 |
| 24. Peer Reviewed Title: Theorizing migration policy: Is there a third way? Author: Boswell C Source: International Migration Review. 2007 Mar;41(1):75-100. Abstract: This article critically reviews theories of migration policy according to two criteria: methodological rigor and explanatory plausibility. It finds that political economy accounts are theoretically robust, but at the price of oversimplification. Neo-institutional theories offer more sophisticated accounts, but fall short on a number of methodological and explanatory counts. As an alternative, this article suggests a theory focusing on the functional imperatives of the state in the area of migration, which shape its responses to societal interests and institutional structures. (author's) Language: English Keywords: GLOBAL | LITERATURE REVIEW | THEORETICAL STUDIES | MIGRATION POLICY | POLITICAL FACTORS | MACROECONOMIC FACTORS | Population Policy | Social Policy | Policy | Sociocultural Factors | Economic Factors Document Number: 312089 |
| 25. Peer Reviewed Title: Predictors of adolescent sexual behavior and intention: a theory-guided systematic review. Author: Buhi ER; Goodson P Source: Journal of Adolescent Health. 2007 Jan;40(1):4-21. Abstract: The purpose was to better understand why adolescents initiate sexual activity at early ages, we conducted a systematic literature review guided by eight key elements outlined in an integrative theoretical framework. Using the matrix method for literature reviews, we extracted--from 69 published studies--statistically significant and nonsignificant findings (related to the attempted prediction/explanation of adolescents' sexual behavior and intention) and organized them using the various integrative model elements. We also assessed these publications' methodological quality including each study's deployment of theory, appropriate design, and data analytic/reporting techniques. Three integrative theoretical framework elements--intention, perceived norms, and an environmental constraint variable, time home alone--emerged as stable predictors of sexual behavior outcomes in this body of literature. This analysis revealed, however, a literature that has remained rather stagnant regarding its methodological quality, over time. Implications for adolescent sexual health promotion practice and research are discussed. (author's) Language: English Keywords: UNITED STATES OF AMERICA | LITERATURE REVIEW | THEORETICAL STUDIES | THEORETICAL MODELS | ADOLESCENTS | SEX BEHAVIOR | FIRST INTERCOURSE | PARENTAL INVOLVEMENT | North America | Americas | Developed Countries | Research Methodology | Youth | Age Factors | Population Characteristics | Demographic Factors | Population | Behavior | Child Rearing Document Number: 310688 |
| 26. Peer Reviewed Title: [Protective factors and resilience in people living with HIV/AIDS] Fatores de protecao relacionados a promocao de resiliencia em pessoas que vivem com HIV/AIDS. Author: de Carvalho FT; de Morais NA; Koller SH; Piccinini CA Source: Cadernos de Saude Publica. 2007 Sep;23(9):2023-2033. Abstract: The aim of this theoretical review was to articulate the resilience concept with key aspects in the lives of people living with HIV/AIDS. We emphasize the analysis of protective factors traditionally related to resilience (personal characteristics and social and affective support networks). The reviewed studies show important protective factors that contribute to the health and well-being of people with HIV/AIDS, such as cognitive coping and acceptance of their HIV status, family participation in treatment and family support, the role of governmental and nongovernmental institutions, and religious beliefs. The concept of resilience defined as a dynamic process that allows human beings to overcome adversities is essential for understanding HIV infection and treatment of AIDS patients. It helps decrease stigmatization and prejudice towards the disease and patients. It also helps alter the notion that living with AIDS is incompatible with well-being and quality of life and fosters the creation of newHIV/AIDS prevention and treatment perspectives. (author's) Language: Portuguese Keywords: BRAZIL | RESEARCH REPORT | THEORETICAL STUDIES | PERSONS LIVING WITH HIV/AIDS | SOCIAL NETWORKS | CARE AND SUPPORT | TREATMENT | QUALITY OF LIFE | AIDS PREVENTION | PSYCHOLOGICAL FACTORS | South America, Eastern | South America | Latin America | Americas | Developing Countries | HIV Infections | Viral Diseases | Diseases | Friends and Relatives | Family and Household | Sociocultural Factors | Health Services | Delivery of Health Care | Health | Medical Procedures | Medicine | Social Welfare | Economic Factors | AIDS | Behavior Document Number: 307963 |
| 27. Title: Nutritional iron deficiency: An evolutionary perspective. Author: Denic S; Agarwal MM Source: Nutrition. 2007 Jul-Aug;23(7-8):603-614. Abstract: Iron deficiency, with or without iron-deficiency anemia, is so ubiquitous that it affects all populations of the world irrespective of race, culture, or ethnic background. Despite all the latest advances in modern medicine, improved nutrition, and the ready availability of cheap oral iron, there is still no good explanation for the widespread persistence of iron deficiency. It is possible that the iron deficiency phenotype is very prevalent because of many factors other than the commonly cited causes such as a decreased availability or an increased utilization of iron. Several thousand years ago, human culture changed profoundly with the agrarian revolution, when humans turned to agriculture. Their diet became iron deficient and new epidemic infections emerged due to crowding and lifestyle changes. There is convincing evidence that iron deficiency protects against many infectious diseases such as malaria, plague, and tuberculosis as shown by diverse medical, historical, and anthropologic studies. Thus, this change of diet increased the frequency of iron deficiency, and epidemic infections exerted a selection pressure under which the iron deficiency phenotype survived better. Multiple evolutionary factors have contributed in making iron deficiency a successful phenotype. We analyze some of the recent findings of iron metabolism, the theories explaining excessive menstruation in human primates, the unexplained relative paucity of hemochromatosis genes, the former medical practice of "blood-letting," and other relevant historical data to fully understand the phenomenon of iron deficiency. We suggest that, due to a long evolutionary persistence of iron deficiency, efforts at its prevention will take a long time to be effective. (author's) Language: English Keywords: GLOBAL | THEORETICAL STUDIES | HISTORICAL REVIEW | EVALUATION | POPULATION | DEFICIENCY DISEASES | MALNUTRITION | SERUM IRON LEVEL | ANEMIA | GENETICS | METABOLIC EFFECTS | METRORRHAGIA | SERUM TOTAL IRON BINDING CAPACITY | CULTURE | Nutrition Disorders | Diseases | Hemic System | Physiology | Biology | Bleeding | Signs and Symptoms | Sociocultural Factors Document Number: 318359 |
| 28. Title: Power, trust, and pleasure: relationship components of contraceptive negotiations. Author: Fennell J Source: [Unpublished] 2007. Presented at the Population Association of America 2007 Annual Meeting, New York, New York, March 29-31, 2007. 32 p. Abstract: With contraception playing an ever-larger role in people's sexual lives throughout the world, both in the prevention of pregnancy and the limiting of sexually transmitted diseases such as HIV, it is increasingly important to understand how people make decisions about contraceptive use. People's decisions about contraceptive use are presumably primarily motivated by the three main purposes of contraception: prevention of pregnancy, prevention of sexually transmitted infections (STI's), and menstrual and fertility regulation. Recent research has begun to pay greater attention to the role of couple dynamics in contraceptive decision-making and is well-integrated with work on fertility decision-making. Unfortunately, this research has been less integrated with work on sexual decision-making, even though the sexual context is a major component of a couple's dynamic contraceptive decisions. Moreover, research on couple's contraceptive decisions has focused more on the methodological than the theoretical implications of studying couples. In this paper, I attempt to ameliorate these issues by introducing a theoretical perspective which addresses the sexual context of couple's contraceptive decisions. The theory of contraceptive decision-making and negotiation which I offer here focuses on three elements of sexual relationships-power relations and trust between partners, and the desire for pleasure by individuals and their partners. I argue that these factors ultimately mediate other important elements of relationships, such as gender, material resources, and romantic love in determining if and when contraceptive negotiations take place, and their outcomes if they do. (excerpt) Language: English Keywords: GLOBAL | THEORETICAL STUDIES | COUPLES | CONTRACEPTIVE USAGE DETERMINANTS | DECISION MAKING | POWER | PARTNER COMMUNICATION | CONDOM USE | SEXUALLY TRANSMITTED DISEASE PREVENTION | GENDER RELATIONS | CULTURE | Family Characteristics | Family and Household | Sociocultural Factors | Contraceptive Usage | Contraception | Family Planning | Behavior | Political Factors | Interpersonal Relations | Risk Reduction Behavior | Sexually Transmitted Diseases | Reproductive Tract Infections | Infections | Diseases | Gender Issues Document Number: 317382 |
| 29. Peer Reviewed Title: Changing service systems for high-risk youth using state-level strategies. Author: Frankford ER Source: American Journal of Public Health. 2007 Apr;97(4):594-599. Abstract: Despite the considerable efforts of those who service youth through the many governmental and voluntary programs, these programs and services are not meeting the challenge of effective intervention to address and ameliorate the problems associated with high-risk youth and their broader social environments. One important reason why these programs are missing the mark is that states continue to fund categorical and fragmented programs, i.e., narrow interventions targeted on "fixing" certain problems or behaviors. Meeting the challenge of effective intervention requires local and regional systemic change that creates public health-oriented, comprehensive, interagency initiatives that target deficient environments and reorganize services and programs to strengthen assets among individuals, families, and communities. The state is the level from which the leadership for that change must come. A values-based conceptual framework that can be adapted to a public health approach is "systems of care," a set of principles that show how services should be delivered to children with serious emotional disturbances and their families-in other words, those for whom treatment rather than prevention is needed. Coordinated systems of care provide a range of services to effectively serve children and their families in the context of their families and communities, rather than to focus just on the singular problems they may have. This systems of care approach can be adapted for positive youth development and prevention strategies with adolescents. (excerpt) Language: English Keywords: UNITED STATES OF AMERICA | RECOMMENDATIONS | THEORETICAL STUDIES | EVALUATION | ADOLESCENTS | COMMUNITY | RISK BEHAVIOR | PREVENTION AND CONTROL | FAMILY RELATIONSHIPS | MENTAL DISORDERS | CHILD DEVELOPMENT | SCHOOL-BASED SERVICES | PRIMARY HEALTH CARE | GOVERNMENT FINANCING | North America | Americas | Developed Countries | Youth | Age Factors | Population Characteristics | Demographic Factors | Population | Residence Characteristics | Population Distribution | Geographic Factors | Behavior | Diseases | Family Characteristics | Family and Household | Sociocultural Factors | Biology | Programs | Organization and Administration | Health Services | Delivery of Health Care | Health | Financial Activities | Economic Factors Document Number: 313265 |
| 30. Title: Epidemiological effects of seasonal oscillations in birth rates. Author: He D; Earn DJ Source: Theoretical Population Biology. 2007 Sep;72(2):274-291. Abstract: Seasonal oscillations in birth rates are ubiquitous in human populations. These oscillations might play an important role in infectious disease dynamics because they induce seasonal variation in the number of susceptible individuals that enter populations. We incorporate seasonality of birth rate into the standard, deterministic susceptible-infectious-recovered (SIR) and susceptible-exposed-infectious-recovered (SEIR) epidemic models and identify parameter regions in which birth seasonality can be expected to have observable epidemiological effects. The SIR and SEIR models yield similar results if the infectious period in the SIR model is compared with the "infected period" (the sum of the latent and infectious periods) in the SEIR model. For extremely transmissible pathogens, large amplitude birth seasonality can induce resonant oscillations in disease incidence, bifurcations to stable multi-year epidemic cycles, and hysteresis. Typical childhood infectious diseases are not sufficiently transmissible for their asymptotic dynamics to be likely to exhibit such behaviour. However, we show that fold and period-doubling bifurcations generically occur within regions of parameter space where transients are phase-locked onto cycles resembling the limit cycles beyond the bifurcations, and that these phase-locking regions extend to arbitrarily small amplitude of seasonality of birth rates. Consequently, significant epidemiological effects of birth seasonality may occur in practice in the form of transient dynamics that are sustained by demographic stochasticity. (author's) Language: English Keywords: GLOBAL | THEORETICAL STUDIES | THEORETICAL MODELS | BIRTH RATE | SEASONAL VARIATION | INFECTION TRANSMISSION | EPIDEMIOLOGY | POPULATION DYNAMICS | Research Methodology | Fertility Measurements | Fertility | Demographic Factors | Population | Infections | Diseases | Public Health | Health Document Number: 320817 |
 |
||
 |
Information & Knowledge for Optimal Health (INFO) Project 111 Market Place Suite 310, Baltimore, MD 21202 Phone: 410-659-6300 Fax: 410-659-6266 Security & Privacy Policy |  |