bluuebunny/crossref_metadata_2025 huggingface dataset:
Spin filtering implemented through Rashba spin-orbit coupling and weak magnetic modulations
Authors: Gong S. J. , Yang Z. Q.
Published: August 2007

We present two theoretical schemes for spin filters in one-dimensional semiconductor quantum wires with spatially modulated Rashba spin-orbit couplings (SOCs) and weak magnetic potentials. In the first scheme, the SOC is periodic and the weak magnetic potential is applied uniformly along the wire. Full spin polarizations with opposite signs are obtained within two separated energy intervals. In the second scheme, the weak magnetic potential is periodic while the SOC is uniform. An ideal negative/positive switching effect for spin polarization is realized by tuning the strength of SOC. The roles of SOC, magnetic potential, and their joint action on the spin filters are analyzed.
Nanoparticles-induced vertical alignment in liquid crystal cell
Authors: Jeng Shie-Chang , Kuo Chia-Wei , Wang Hsing-Lung , Liao Chi-Chang
Published: August 2007

This letter reports that adding nanoparticles in the negative dielectric anisotropic liquid crystal (LC) cell can exhibit the properties of vertical alignment without using alignment layers. The electro-optical properties of this nanoparticles-induced vertical alignment in the LC cell are very similar to the conventional homeotropic LC cell with alignment layers. This technique can be used to fabricate a flexible LC display requiring a low temperature process.
Simulation of two-dimensional infrared spectroscopy of amyloid fibrils
Authors: Zhuang Wei , Abramavicius Darius , Voronine Dimitrii V. , Mukamel Shaul
Published: August 2007

We propose to use infrared coherent two-dimensional correlation spectroscopy (2DCS) to characterize the fibril structure of Ab42, the dominant composition of Ab deposit, which is crucial for investigating its toxicity and aggregation mechanism. By optimizing the pulse polarization configurations with a genetic algorithm combined with sensitivity analysis, we obtained signals with well resolved cross-peak features attributed to the couplings within and between different structural motifs. These signals may provide new constraints for refining of the currently available NMR structure. Two-dimensional correlation spectroscopy also can differentiate the turn structure of Ab42 and other Ab derivatives.
Molecular dioxygen enters the active site of 12/15-lipoxygenase via dynamic oxygen access channels
Authors: Saam Jan , Ivanov Igor , Walther Matthias , Holzhütter Hermann-Georg , Kuhn Hartmut
Published: August 2007

Cells contain numerous enzymes that use molecular oxygen for their reactions. Often, their active sites are buried deeply inside the protein, which raises the question whether there are specific access channels guiding oxygen to the site of catalysis. Choosing 12/15-lipoxygenase as a typical example for such oxygen-dependent enzymes, we determined the oxygen distribution within the protein and defined potential routes for oxygen access. For this purpose, we have applied an integrated strategy of structural modeling, molecular dynamics simulations, site-directed mutagenesis, and kinetic measurements. First, we computed the 3D free-energy distribution for oxygen, which led to identification of four oxygen channels in the protein. All channels connect the protein surface with a region of high oxygen affinity at the active site. This region is localized opposite to the nonheme iron providing a structural explanation for the reaction specificity of this lipoxygenase isoform. The catalytically most relevant path can be obstructed by L367F exchange, which leads to a strongly increased Michaelis constant for oxygen. The blocking mechanism is explained in detail by reordering the hydrogen-bonding network of water molecules. Our results provide strong evidence that the main route for oxygen access to the active site of the enzyme follows a channel formed by transiently interconnected cavities whereby the opening and closure are governed by side chain dynamics.
Methoxychlor and Its Metabolites Inhibit Growth and Induce Atresia of Baboon Antral Follicles
Authors: Gupta Rupesh K. , Aberdeen Graham , Babus Janice K. , Albrecht Eugene D. , Flaws Jodi. A.
Published: August 2007

Methoxychlor (MXC), an organochlorine pesticide, inhibits growth and induces atresia of antral follicles in rodents. MXC metabolites, mono-OH MXC (mono-OH) and bis-OH MXC (HPTE), are thought to be more toxic than the parent compound. Although studies have examined the effects of MXC in rodents, few studies have evaluated the effects of MXC in primates. Therefore, the present study tested the hypothesis that MXC, mono-OH, and HPTE inhibit growth and induce atresia of baboon antral follicles. To test this hypothesis, antral follicles were isolated from adult baboon ovaries and cultured with vehicle (dimethylsulfoxide; DMSO), MXC (1–100 μg/ml), mono-OH (0.1–10 μg/ml), or HPTE (0.1–10 μg/ml) for 96 hr. Growth was monitored at 24 hr intervals. After culture, follicles were processed for histological evaluation of atresia. MXC, mono-OH, and HPTE significantly inhibited follicular growth and increased atresia compared to DMSO. Moreover, the adverse effects of MXC and its metabolites on growth and atresia in baboon antral follicles were observed at lower (100-fold) doses than those causing similar effects in rodents. These data suggest that MXC and its metabolites inhibit growth and induce atresia of baboon antral follicles, and that primate follicles are more sensitive to MXC than rodent follicles.
Time-Dependent Changes in Post-Mortem Testis Histopathology in the Rat
Authors: Bryant Bronwyn H. , Boekelheide Kim
Published: August 2007

To clarify the contribution of spontaneous or autolytic post-mortem changes to testis histopathology, the testes of adult rats were examined after animals were left at room temperature for 12, 24, 36, and 48 hours postmortem (n = 2 for all time points except 0 hours postmortem, where n = 3). A progressive decrease in testis weight and seminiferous tubule diameter was observed, as well as detachment of the seminiferous epithelium from the basement membrane. As early as 12 hours postmortem, there was observable clumping and margination of chromatin in Leydig cells, Sertoli cells, spermatogonia, spermatocytes, and step 7–10 spermatids; extensive disintegration of Sertoli cells and residual bodies by 24 hours postmortem; and TUNEL positivity of Leydig cells (by 36 hours postmortem) and step 19 spermatids (at 48 hours postmortem). These findings will aid in ensuring proficient histopathological analysis of testes in toxicity studies.
An Undifferentiated Sarcoma in a Rat Resembling Extraskeletal Myxoid Chondrosarcoma in Man
Authors: Nakamura Keigo , Shibuya Kazumoto , Hirai Takuya , Nunoya Tetsuo
Published: August 2007

A soft tissue tumor occurring in the inguinal subcutaneous tissue was detected in a 109-week-old male F344 rat. Macroscopically, the tumor mass showed no skeletal relationship and a gelatinous multinodular appearance. Histologically, the tumor consisted of irregular lobules separated by scant fibrous septa. In each lobule, tumor cells were arranged in cords and strands in the plentiful myxoid stroma. The tumor cells showed marked pleomorphism, and had large, round to ovoid nuclei and abundant eosinophilic cytoplasm. Mitotic figures were often seen. Myxoid stroma of the tumor contained a large amount of acid mucopolysaccharides and collagen type II, which were demonstrated by histochemistry and immunohistochemistry respectively. The tumor cells showed positive immunoreactivities for vimentin and S100 protein. Ultrastructural examination revealed that the tumor cells had a large amount of mitochondria, Golgi complex and dilated rough endoplasmic reticulum containing amorphous material, and the myxoid stroma contained collagenous fibrils and proteoglycan particles. Based on these results, the present tumor in a rat resembled extraskeletal myxoid chondrosarcoma in man.
Interpersonal Forgiveness among Kuwaiti Adolescents and Adults
Authors: Ahmed Ramadan A. , Azar Fabiola , Mullet Etienne
Published: August 2007

The willingness to forgive was examined in a sample of 517 Kuwaiti citizens, aged 12 to 55 years. Participants were instructed first to read a certain number of stories (in which a harmful act was committed against a child) and then to express their willingness to forgive in each case. The stories included four factors: intent to harm, religious proximity, presence/absence of apologies, and cancellation of consequences. A high level of willingness to forgive was observed among the Kuwaitis studies, irrespective of participants' age and gender. The impact of the religious proximity factor was limited to a very small fraction of the sample.
Economic War and Democratic Peace
Authors: Goenner Cullen F.
Published: August 2007

Research has shown that democracies rarely, if ever, engage each other in war and are less likely to have militarized disputes than when interacting with authoritarian regimes. Economic sanctions are an alternative to militarized conflict viewed by the masses as more acceptable. The conflict-inhibiting effects of democratic norms and institutions are thus weakened with respect to the use of sanctions. This paper examines whether a country's decision to initiate sanctions is influenced by its regime type as well as that of the potential target. The results for the period 1950 to 1990 indicate that the more democratic a country is, the more likely it is to initiate sanctions. Democracies, however, are less likely to target other democratic regimes relative to nondemocratic regimes. With respect to sanctions use, pairs of democracies are not peaceful.
The Effects of Liberalism on the Terrestrial Environment
Authors: Li Quan , Reuveny Rafael
Published: August 2007

In recent decades, many countries have adopted, to various degrees, the ideologies of commercial and republican liberalism. One salient aspect of the spread of commercial liberalism in the world has been the growth in international trade. The spread of republican liberalism has manifested itself by the rise in the level of democracy in countries over time. What are the implications of trade and democracy for the terrestrial environment? Two bodies of literature are relevant to this question: one studies the effect of trade on the environment, while a second body focuses on the effect of democracy on the environment. The effects of both forces on the environment are debated theoretically and empirically. The two bodies of literature have generally developed separately, and the effects of trade and democracy have not been evaluated in the same model. This paper discusses the theoretical effects of trade and democracy on the environment, and develops a statistical model to study these effects on the terrestrial environment in the areas of deforestation and land degradation. The results indicate that a rise in trade openness reduces deforestation in autocracy and increases deforestation in democracy, and the effect is similar for the less developed countries (LDCs) and the developed countries (DCs). A rise in trade openness reduces land degradation, but the effect is not robust and does not depend on regime type. A rise in democracy increases deforestation and reduces land degradation, but these effects are weaker in LDCs than in DCs. In addition, the effect of democracy on deforestation is stronger when trade openness is high. The effect of democracy on land degradation does not depend on trade openness. The paper concludes with an examination of the implications of these results for public policy.
Fighting over Oil: Introducing a New Dataset
Authors: Lujala Päivi , Ketil Rod Jan , Thieme Nadja
Published: August 2007

Recent research on armed civil conflict has suggested that oil-producing countries tend to experience conflict more often than their non-oil-producing counterparts. However, this research relies on weak and incomplete measures of petroleum resources. To facilitate more rigorous research on the possible links between hydrocarbons and conflict, this paper presents and describes a new global dataset, PETRODATA. The dataset includes 890 onshore and 383 offshore locations with geographic coordinates and information on the first oil or gas discovery and production year. PETRODATA allows researchers to control for both the spatial and temporal overlap of regions with hydrocarbon reserves and armed conflict. To illustrate the use of data, we conduct a duration analysis on the types of armed civil conflict. The results suggest that oil and gas located in conflict area lengthen governmental conflicts but have no effect on conflicts over territory.
Alliance Politics during the Cold War: Aberration, New World Order, or Continuation of History?
Authors: Ashley Leeds Brett , Mattes Michaela
Published: August 2007

Scholars have often wondered whether the nature of alliance politics fundamentally changed during the bipolar nuclear era characterized by the Cold War. The extension of the Alliance Treaty Obligations and Provisions (ATOP) dataset to include the years from 1815 to 2003 allows us the ability to evaluate systematically whether the Cold War period was an aberration, different both from the periods that preceded it and those that followed it, the beginning of a new alliance politics that has continued in the post—Cold War era, or similar in dynamics to eras both before and since. We begin this descriptive project here. While we find some evidence of the distinctness of the Cold War era, what is more notable in the design of alliances is a trend over time away from “reactive alliances” (which are designed to deal with specific crises) and toward “standing alliances” (which are broader and more enduring). In terms of the effects of alliances, we do find evidence that Cold War dynamics are distinct from those of prior eras. In a replication of a well-known study by Russett and Oneal (2001), we reinforce the finding that shared alliance commitments are related to peace during the Cold War, but not in earlier eras. In addition, we demonstrate that the effect of shared alliances on peace depends on the type of alliance commitment.
Mill and Senior on London's Water Supply: Agency, Increasing Returns, and Natural Monopoly
Authors: Tynan Nicola
Published: August 2007

In recent years, water utilities have received increasing attention. Issues of ownership and market structure have been the focus of academic research, policy debates and grassroots activism. These recent concerns echo the contentious debate that raged over water supply in nineteenth century London from 1810 to 1902. Nassau W. Senior and John Stuart Mill were major players in the debates, as both theorists and policy makers.
The Macroeconomic thought of Nicholas Barbon
Authors: Ullmer James H.
Published: August 2007

Nicholas Barbon (1640–1698) is little appreciated by most historians of economic thought. He is sporadically mentioned in a few writings—probably the most well-known being the favorable reference to him made by John Maynard Keynes (1883–1946) in The General Theory of Employment, Interest, and Money (Keynes 1936, p. 359). The fullest treatment of Barbon's economic ideas is contained in The Origin of Scientific Economics: English Economic Thought 1660–1776 by William Louis Letwin (Letwin 1963, pp. 48–75). Letwin considers a major defect of Barbon's first purely scientific inquiry into economics, A Discourse of Trade (Barbon 1690), and by implication, his other economic writings, to be “the logical incoherence of its parts” (Letwin 1963, p. 57). This criticism is not surprising in light of the pre-paradigm period in which Barbon was writing.
Understanding and managing hypertension in an African sub-district: A multidisciplinary approach1
Authors: Thorogood Margaret , Connor Myles D. , Lewando Hundt Gillian , Tollman Stephen M.
Published: August 2007

Aims: To use a multidisciplinary approach to describe the prevalence, lay beliefs, health impact, and treatment of hypertension in the Agincourt sub-district. Methods: A multidisciplinary team used a range of methods including a cross-sectional random sample survey of vascular risk factors in adults aged 35 years and older, and rapid ethnographic assessment. People who had suffered a stroke were identified by a screening questionnaire followed by a detailed history and examination by a clinician to confirm the likely diagnosis of stroke. Workshops were held for nurses working in the local clinics and an audit of blood pressure measuring devices was carried out. Results: Some 43% of the population 35 and over had hypertension. There was no relationship with gender but a strong positive relationship with age. Illnesses were classified by the population as being either African, with personal or social causes, or White/Western, with physical causes. The causes of hypertension were stated to be both physical and social. Main sources of treatment were the clinics and hospitals but people also sought help from churches and traditional healers. Some 84% of stroke survivors had evidence of hypertension. Few people received treatment for hypertension, although good levels of control were achieved in some. Barriers to providing effective treatment included unreliable drug supply and unreliable equipment to measure blood pressure. Conclusions: Hypertension is a major problem among older people in Agincourt. There is potential for effective secondary prevention. The potential for primary prevention is less clear. Further information on diet is required.
Household transitions in rural South Africa, 1996—2003
Authors: Wittenberg Martin , Collinson Mark A.
Published: August 2007

Aims: To investigate changes in household structure in rural South Africa over the period 1996—2003, a period marked by politico-structural change and an escalating HIV/AIDS epidemic. In particular, the authors examine whether there is dissolution of extended family living arrangements. Methods: Data from the Agincourt demographic surveillance system, in rural north-eastern South Africa, and the rural sub-samples of selected nationally representative data sets were used to compare changes in the cross-sectional distribution of household types. Surveillance system data were further analysed to estimate the transition probabilities between household types. The latent pressures for change within the Agincourt area were analysed by projecting the household transition probabilities forward and comparing the projected steady-state distributions to the current distributions. Results: The national surveys show dramatic changes in the social structure in rural areas, particularly an increase in the importance of single person households. These trends are not confirmed in the surveillance system data. The national ``changes'' can possibly be ascribed to changes in sampling frames or household definitions. The transition probabilities within the Agincourt area show considerable changes between household types, despite a slower change in the aggregate distributions. The most important projected long-run changes are an increase in the proportion of three-generation linear households. ``Simpler'' household types such as single person households and nuclear households will become relatively less common. Conclusions: The structure of households is evolving under the pressure of social change and increased mortality due to HIV/AIDS. There is no evidence, however, that the social fabric is unravelling or that individuals are becoming increasingly isolated residentially.
Does money empower the elderly? Evidence from the Agincourt demographic surveillance site, South Africa1
Authors: Case Anne , Menendez Alicia
Published: August 2007

Aims: To quantify the impact of the South African old age (social) pension on outcomes for pensioners and the prime-aged adults and children who live with them, and to examine alternative means by which pensions affect household outcomes. Methods: We collected socioeconomic data on 290 households in the Agincourt demographic surveillance area (DSA), stratifying our sample on the presence of a household member age-eligible for the old-age pension (women aged 60 and older, men aged 65 and older). Results: The presence of a pensioner significantly reduces household reports that adults and, separately, children missed meals because there was not enough money for food. In addition, girls are significantly more likely to be enrolled in school if they are living with a pensioner, an effect that is driven entirely by living with a female pensioner. Our results are consistent with a model in which pensioners have a greater say in household functioning once they begin to receive their pensions. Conclusions: We find a program targeted toward the elderly plays a significant role in children's health and development.
An introduction to the General Temporal Data Model and the Structured Population Event History Register (SPEHR)
Authors: Clark Samuel J.
Published: August 2007

There are some 37 demographic surveillance system sites active in sub-Saharan Africa, Asia and Central America. These sites, and other longitudinal population and health research projects, generate data over time in order to describe and explain the event histories of individuals and the populations they constitute. This note addresses key data management challenges presented by such complex temporal data-gathering efforts. Ideas supporting a standard definition for temporal population data, and a standard design for temporal databases to improve management of longitudinal population data, are presented and briefly discussed.
Coping with the cost burdens of illness: Combining qualitative and quantitative methods in longitudinal, household research
Authors: Goudge Jane , Gumede Tebogo , Gilson Lucy , Russell Steve , Tollman Stephen M. , Mills Anne
Published: August 2007

Over the last 10—15 years, poor African households have had to cope with the burden of increased levels of chronic illness such as HIV/AIDS. How do these households cope with the cost burdens of ill health and healthcare, and has this burden further impoverished them? What policy responses might better support these households? This is a report from the field of the South African Costs and Coping study (SACOCO) — a longitudinal investigation of household experiences in the Agincourt health and demographic surveillance site.
Returning home to die: Circular labour migration and mortality in South Africa 1
Authors: Clark Samuel J. , Collinson Mark A. , Kahn Kathleen , Drullinger Kyle , Tollman Stephen M.
Published: August 2007

Aim: To examine the hypothesis that circular labour migrants who become seriously ill while living away from home return to their rural homes to convalesce and possibly to die. Methods: Drawing on longitudinal data collected by the Agincourt health and demographic surveillance system in rural northeastern South Africa between 1995 and 2004, discrete time event history analysis is used to estimate the likelihood of dying for residents, short-term returning migrants, and long-term returning migrants controlling for sex, age, and historical period. Results: The annual odds of dying for short-term returning migrants are generally 1.1 to 1.9 times (depending on period, sex, and age) higher than those of residents and long-term returning migrants, and these differences are generally highly statistically significant. Further supporting the hypothesis is the fact that the proportion of HIV/TB deaths among short-term returning migrants increases dramatically as time progresses, and short-term returning migrants account for an increasing proportion of all HIV/TB deaths. Conclusions: This evidence strongly suggests that increasing numbers of circular labour migrants of prime working age are becoming ill in the urban areas where they work and coming home to be cared for and eventually to die in the rural areas where their families live. This shifts the burden of caring for them in their terminal illness to their families and the rural healthcare system with significant consequences for the distribution and allocation of health care resources.
Fertility trends and net reproduction in Agincourt, rural South Africa, 1992—2004 1
Authors: Garenne Michel L. , Tollman Stephen M. , Collinson Mark A. , Kahn Kathleen
Published: August 2007

Aims: To analyse trends in fertility rates and net reproduction rates in Agincourt, a rural area of South Africa located in the former homeland of Gazankulu near the Mozambican border. Trends are analysed in the context of widely available modern contraceptive methods and increasing HIV/AIDS. Methods: A health and demographic surveillance system has been in place since 1992, covering a population of approximately 70,000 persons, with an annual census update and comprehensive recording of births and deaths. It was complemented by a retrospective study of fertility at baseline. Retrospective and prospective data were used to calculate trends in fertility, survival, and net reproduction. When possible, they were compared with data from other censuses and surveys in the same ethnic group. Results: The fertility transition has almost ended over a course of 25 years in Agincourt. The total fertility rate (TFR) averaged 6.0 in 1979 and 2.3 in 2004. Fertility declined in proportionate fashion in all age groups including adolescents in the recent period. The net reproduction rate (NRR) declined from 1.8 to 1.0 during the prospective period (1992—2004). At current rates of change in fertility and mortality, the NRR can be expected to reach 0.63 by the year 2010. Conclusions: The situation of a below-replacement fertility level is new for rural Africa, and is likely to have many demographic, economic and social implications. The population could decline in the country as a whole, and is nearly static in Agincourt because of negative migration flows balancing the small excess from natural increase.
``Taking care of my own blood'': Older women's relationships to their households in rural South Africa
Authors: Schatz Enid J.
Published: August 2007

Aim: This paper examines financial, emotional, and physical responsibilities elderly women are being asked to take on due to the incapacity of their adult children to care for the next generation; such incapacity is likely to increase as the HIV/AIDS epidemic worsens. Methods: This paper combines quantitative and qualitative data. Census data from the Agincourt health and demographic surveillance system (AHDSS) describe the presence of the elderly (specifically women over the age of 60 and men over the age of 65) in households in the Agincourt study site. Semi-structured interviews with 30 female residents aged 60—75 complement the census data by exploring the roles that older women, in particular, are playing in their households. Results: An elderly man and/or woman lives in 27.6% of households; 86% of elders live with non-elders. Households with a woman over the age of 60 resident (as opposed to those without) are twice as likely to have a fostered child living in the household and three times as likely to have an orphaned child in the household. Elderly women face financial, physical, and emotional burdens related to the morbidity and mortality of their adult children, and to caring for grandchildren left behind due to adult children's mortality, migration, (re)marriage, and unemployment. Conclusions: Older women provide crucial financial, physical, and emotional support for ill adult children and fostered and orphaned grandchildren in their households. As more prime-aged adults suffer from HIV/AIDS-related morbidity and mortality, these obligations are likely to increase.
The social context of children's nutritional status in rural South Africa 1
Authors: Madhavan Sangeetha , Townsend Nicholas
Published: August 2007

Aim: To investigate the relationship between children's nutritional status and a series of measures capturing both the current status and the lifetime history of their connection with adult caregivers in the Agincourt sub-district of rural South Africa. Methods: Using data on a sample of 202 children from a recent ethnographic study of children's social connections and well-being, the authors (1) compare height for age and weight for age to an accepted international standard and (2) conduct bivariate analyses of the relationships between selected measures of social connection and extreme deviations below expected weight and expected height. Results: Fitted curves for weight for age and height for age fall between the 5th and 50th percentiles of CDC growth curves. Compromised nutrition, defined as being more than two standard deviations below expected height or weight, is associated with the death or non-co-residence of the mother, and with the absence of financial support from the father. The co-residence of maternal female kin as substitutes for the mother do not fully compensate for her absence. Conclusions: The findings highlight the importance of parental living arrangements, parental financial support, birth order and the composition of sibling sets, and lifetime residential patterns in facilitating access to nutrition.
Migration, settlement change and health in post-apartheid South Africa: Triangulating health and demographic surveillance with national census data1
Authors: Collinson Mark A. , Tollman Stephen M. , Kahn Kathleen
Published: August 2007

Background: World population growth will be increasingly concentrated in the urban areas of the developing world; however, some scholars caution against the oversimplification of African urbanization noting that there may be ``counterurbanization'' and a prevailing pattern of circular rural—urban migration. The aim of the paper is to examine the ongoing urban transition in South Africa in the post-apartheid period, and to consider the health and social policy implications of prevailing migration patterns. Methods: Two data sets were analysed, namely the South African national census of 2001 and the Agincourt health and demographic surveillance system. A settlement-type transition matrix was constructed on the national data to show how patterns of settlement have changed in a five-year period. Using the sub-district data, permanent and temporary migration was characterized, providing migration rates by age and sex, and showing the distribution of origins and destinations. Findings: The comparison of national and sub-district data highlight the following features: urban population growth, particularly in metropolitan areas, resulting from permanent and temporary migration; prevailing patterns of temporary, circular migration, and a changing gender balance in this form of migration; stepwise urbanization; and return migration from urban to rural areas. Conclusions: Policy concerns include: rural poverty exacerbated by labour migration; explosive conditions for the transmission of HIV; labour migrants returning to die in rural areas; and the challenges for health information created by chronically ill migrants returning to rural areas to convalesce. Lastly, suggestions are made on how to address the dearth of relevant population information for policy-making in the fields of migration, settlement change and health.
Living with death in a time of AIDS: A rural South African case study
Authors: Posel Deborah , Kahn Kathleen , Walker Liz
Published: August 2007

Aims: To examine how a rural community profoundly affected by escalating rates of largely AIDS-related deaths of young and middle-aged people makes sense of this phenomenon and its impact on their everyday lives. Methods: Data were collected in Agincourt subdistrict, Limpopo Province. Twelve focus groups were constituted according to age and gender and met three times (a total of 36 focus-group discussions [FGDs]). The FGDs explored sequentially people's expectations of their lives in the ``new'' South Africa, their interpretations of the acceleration of death amongst the young and middle-aged, and their understandings of HIV/AIDS. Discussions were recorded, fully transcribed, and thematically analysed. Results: Respondents acknowledged escalating death rates in their community, yet few referred directly to HIV/AIDS as the cause. Rather, respondents focused on the social and cultural causes of death, including the erosion of cultural norms and traditions such as cultural taboos on sex. There are many competing versions of what HIV/AIDS is, what causes it and how it is spread, ranging from scientific explanations to conspiracy theories. Findings highlight the relationship between AIDS and other traditional diseases with some respondents suggesting that AIDS is a new form of other longstanding illnesses. Conclusions: This study points to the centrality of cultural explanations in understanding ``bad death'' (AIDS death) in the Agincourt area. Physical illness is understood to be a symptom of ``cultural damage''. Implications of this for public health practice and research are outlined.
Evaluating access to a child-oriented poverty alleviation intervention in rural South Africa1
Authors: Twine Rhian , Collinson Mark A. , Polzer Tara J. , Kahn Kathleen
Published: August 2007

Background: In April 1998, the South African government introduced the child-support grant as a poverty-alleviation measure to support the income of poor households and enable them to care for the child. Aims: This research aimed to measure equity of access to applications for the child-support grant in an area characterized by poverty. Three questions were addressed: (i) How does socioeconomic status affect the probability of a household applying for a child-care grant? (ii) What household and caregiver characteristics are associated with child-care-grant application? (iii) What barriers to access are experienced by households that do not apply for the child-care grant? Methods: The study population of 6,725 households with at least one age-eligible child was drawn from the Agincourt field site, a rural sub-district of South Africa. Data used were obtained from health and demographic surveillance, a child-grant questionnaire, and a household-asset survey. Descriptive cross-tabulations and multivariate logistic regression were used in the analysis. Results: Although these grants are intended as a pro-poor intervention, the poorest households are less likely to apply for grants than those in higher socioeconomic bands. Households in lower socioeconomic bands experienced barriers in accessing grants; these related to lack of official documentation, education level of the caregiver and household head, and distance from government service offices. Conclusions: Enhancing access will require improved provision of birth certificates and identity documents, efficient coordination and service provision from a range of rural government offices, and creative methods of communication.
Research into health, population and social transitions in rural South Africa: Data and methods of the Agincourt Health and Demographic Surveillance System1
Authors: Kahn Kathleen , Tollman Stephen M. , Collinson Mark A. , Clark Samuel J. , Twine Rhian , Clark Benjamin D. , Shabangu Mildred , Gómez-Olivé Francesc Xavier , Mokoena Obed , Garenne Michel L.
Published: August 2007

Rationale for study: Vital registration is generally lacking in infrastructurally weak areas where health and development problems are most pressing. Health and demographic surveillance is a response to the lack of a valid information base that can provide high-quality longitudinal data on population dynamics, health, and social change to inform policy and practice. Design and measurement procedures: Continuous demographic monitoring of an entire geographically defined population involves a multi-round, prospective community study, with annual recording of all vital events (births, deaths, migrations). Status observations and special modules add value to particular research areas. A verbal autopsy is conducted on every death to determine its probable cause. A geographic surveillance system supports spatial analyses, and strengthens field management. Population and sample size considerations: Health and demographic surveillance covers the Agincourt sub-district population, sited in rural north-eastern South Africa, of some 70,000 people (nearly a third are Mozambican immigrants) in 21 villages and 11,700 households. Data enumerated are consistent or more detailed when compared with national sources; strategies to improve incomplete data, such as counts of perinatal deaths, have been introduced with positive effect. Basic characteristics: A major health and demographic transition was documented over a 12-year period with marked changes in population structure, escalating mortality, declining fertility, and high levels of temporary migration increasing particularly amongst women. A dual burden of infectious and non-communicable disease exists against a background of dramatically progressing HIV/AIDS. Potential and research questions: Health and demographic surveillance sites — fundamental to the INDEPTH Network — generate research questions and hypotheses from empirical data, highlight health, social and population priorities, provide cost-effective support for diverse study designs, and track population change and the impact of interventions over time.
Motivation, overtraining, and burnout: Can self‐determined motivation predict overtraining and burnout in elite athletes?
Authors: Lemyre Pierre‐Nicolas , Roberts Glyn C. , Stray‐Gundersen Jim
Published: August 2007

The aim of this study was to determine whether quality of self‐determined motivation at the start of the competitive season in elite athletes and symptoms of overtraining can predict athlete burnout propensity at the end of the season. The participants were 141 elite winter sport athletes. In September, at the beginning of the season, the athletes responded to a self‐determined motivation questionnaire, while they answered questions assessing overtraining symptoms and burnout in March, at the end of the season. Findings indicated that self‐determined motivation and symptoms of overtraining were negatively and positively linked respectively to dimensions of athlete burnout. The results suggest that self‐determined motivation and symptoms of overtraining are both independently linked to signs of burnout in elite athletes and that although no moderating effect was found, pairing self‐determined motivation with symptoms of overtraining increased the prediction of burnout in athletes at the end of the season. Our findings are in line with those of recent research (Cresswell & Eklund, 2005; Lemyre, Treasure, & Roberts, 2006) and support a motivational approach to study burnout in elite athletes.
Leisure‐time physical activity in relation to the risk of breast cancer
Authors: Kruk Joanna
Published: August 2007

The incidence of breast cancer has increased over the past decades. To the author's knowledge, no published studies have addressed leisure‐time physical activity and breast cancer risk in Polish women. I conducted a case‐control study of 257 women who underwent a breast cancer operation during 1993–1998, in Szczecin hospitals, and a control group of 565 women, free of any cancer diagnosis, to investigate the role of lifetime, leisure‐time physical activity on breast cancer risk. The participants were sent a detailed structured questionnaire including questions on socio‐demographics, gynaecological factors (age at menarche, age at birth of the first child, total number of full‐term pregnancies), lifestyle factors (lifetime exercise/sports activity, alcohol consumption, fruit and vegetables consumed, experience of psychological stress), anthropometric measures (weight, height), physical activity at work, and disease history. Logistic regression analyses were used to estimate the odds ratios with 95% confidence intervals (CIs).

After adjusting for potential confounding variables, the odds ratios for increasing levels of leisure‐time physical activity were 1.00 (reference), 0.47 (95% CI=0.36–0.89), and 0.22 (95% CI=0.14–0.35), respectively, for low (women consistently sedentary), intermediate, and high levels (P trend<0.0001). In a stratified analysis, the protective effect of leisure‐time physical activity appeared to be stronger among women who experienced menarche at age ≤12 years, women with a higher body mass index, and women who rarely consumed fruit and vegetables. The reduced risk of breast cancer associated with recreational physical activity was also greater for participants who had not experienced psychological stress.

These findings provide further support for the hypothesis that increased leisure‐time physical activity throughout life is associated with a decreased risk of breast cancer.
Psychosocial correlates of stages of change in physical activity in an adult community sample
Authors: Lorentzen Catherine , Ommundsen Yngvar , Holme Ingar
Published: August 2007

Two important public health challenges are to influence sedentary people to become physically active, and to influence active people to maintain their level of activity. Psychosocial factors might have important influencing properties in this regard. The aims of this study were threefold: (1) to examine the relationships between selected psychosocial factors and physical activity stages of change; (2) to examine moderating influences of socio‐demographic and anthropometric factors in these relationships; and (3) to identify possible interactions between psychosocial factors in their relation to stages of change.

Altogether, 2336 men and women aged 31–67 (mean 48, s=10) years completed self‐administered questionnaires that assessed stages of change in physical activity, self‐efficacy, social support, perceived behavioural control, attitude, and identity. The psychosocial factors were measured by instruments derived or modified from instruments that have previously been shown to have acceptable validity and reliability. The statistical tests employed were descriptive and frequency analyses, Pearson's correlations, multiple regressions, multivariate analyses of variance, analyses of variance, and Tukey post‐hoc comparison tests.

Analyses revealed that self‐efficacy in the face of psychological barriers, support from family and from friends, perceived behavioural control, and identity explained 42% of the variance in stages of physical activity behaviour change. Results further showed that all measured psychosocial variables differed significantly by stages of change, with almost every stage having significantly different psychosocial variable scores than every other stage. Although we found no moderating effects of socio‐demographic or anthropometric variables on these relationships, social support from family and social support from friends, identity and social support from family, as well as perceived behavioural control and self‐efficacy faced with psychological barriers were found to interact with respect to their relationships with stages of change.

The study identified a strong set of psychosocial correlates of physical activity stages of change as well as significant interactions between particular correlates in these relationships. The findings might provide guidance in the design of stage‐matched interventions to promote physical activity among adults. Further work is needed to confirm these findings as well as to provide evidence of the causality in the observed relationships.
Morphological characteristics of Olympic slalom canoe and kayak paddlers
Authors: Ridge Barry R. , Broad Elizabeth , Kerr Deborah A. , Ackland Timothy R.
Published: August 2007

Sidney and Shephard (1973) were the first to report on the morphology of slalom paddlers and characterized them as having “a substantial standing height and lean body mass, good general muscle development with particular emphasis on the leg muscles”. The purpose of this study was to analyse the morphological characteristics of Olympic slalom kayak and canoe paddlers to determine whether they possess unique physique or structural characteristics that provide an advantage for their sport. Thirty‐one male and 12 female slalom paddlers were measured using a battery of 36 anthropometric dimensions in the 15‐day period before competition at the 2000 Olympic Games. Male slalom paddlers were older, lighter, shorter, and leaner than previously reported slalom paddlers and had similar height and weight to a reference population of non‐athletes. Compared with Olympic sprint paddlers, male slalom paddlers were older, lighter and shorter, and had similar body fat and almost identical proportionality characteristics. Female slalom paddlers were taller, lighter, older, and less fat than those reported previously. They were taller and lighter than the reference population of non‐athletes and of similar age and height but lighter and leaner than the Olympic sprint paddlers. While a high brachial index was reported for both male and female slalom paddlers, the Best male paddlers (those ranked in the top 10 placings) were more compact, had smaller proportional hip girth, and showed a tendency for smaller proportional hip breadth but a larger proportional waist girth than the Rest (those not ranked in the top 10 placings). Changes to the technical aspect of the events and to competition rules and the nature and approach to training were explored as possible reasons for some of these differences. We outline the contribution this research makes to talent identification and highlight the need for further research.
Modelling and interpretation of MHD active control experiments in RFX-mod
Authors: Paccagnella R. , Terranova D. , Zanca P.
Published: August 2007

A clean magnetic boundary, i.e. a vanishing radial magnetic field, is important for reversed field pinch operation. In order to achieve this target a large modification of the RFX device (a= 0.45 m,R= 2 m) into RFX-mod has been realized and 192 individually controlled saddle coils which provide a flexible control of magnetic boundary have been installed. Recent experiments have shown that this change has produced a significant improvement in plasma magnetohydrodynamic (MHD) behaviour.

This paper discusses 3D MHD numerical simulations aimed at interpreting these results. In particular it is shown that these simulations can predict the measured level of magnetic fluctuations in different operational scenarios. They can also predict the dominat modes and show in general an agreement with experiments. A specific comparison for a resistive wall mode branch is also done, showing differences between simulations and experiments which may indicate the presence of field errors.
H-mode-like transition and ELM-like bursts in LHD with thick ergodic layer
Authors: Morita S. , Morisaki T. , Goto M. , Tanaka K. , Chowdhuri M.B. , Ikeda K. , Katai R. , Masuzaki S. , Nagaoka K. , Narihara K. , Oka Y. , Osakabe M. , Sakakibara S. , Takeiri Y. , Tsumori K. , Yamazaki H. , Watanabe K.Y.
Published: August 2007

In H2discharges of large helical device (LHD), H-mode-like transition has been obtained with edge localized mode (ELM)-like bursts in an outwardly shifted configuration ofRax= 4.00 m with an extremely thick ergodic layer, where the ι/2π = 1 position is located in the middle of the ergodic layer. This H-mode-like transition can be triggered by changingPNBI(<12 MW) from 3 beams to 2 beams in a density range (4–8) × 1013 cm−3. The spontaneous H-mode-like transition is also observed during a stable discharge with constant heating power and density, where a steep edge pressure gradient is formed at the ι/2π = 1 position. The ELM-like bursts occurred in the ergodic layer accompanied with density bursts. It is found that the density bursts triggered at the ι/2π = 1 position in the ergodic layer instantaneously propagate outward beyond the ergodic layer with positive density pulse, and a few ms later also begin to propagate inward from the ergodic layer with negative density pulse to recover the previous edge density profile. In the case of He discharges no H-mode-like transition and ELM-like bursts are observed. The frequency of the ELM-like bursts increases with heating power, e.g. 50 Hz (3 MW)–100 Hz (5 MW) atne= 4 × 1013 cm−3. The external resonant magnetic field to generate a staticm/n= 1/1 island inside the ergodic layer is supplied to the ELM-like bursts. It is also found that the externally supplied magnetic field makes a clear response even in the ergodic layer. As a result, the frequency of the ELM-like bursts decreases, e.g. from 60 to 45 Hz. The present study strongly indicates that those phenomena observed in LHD are quite different from the ones which have been observed in tokamaks until now.