Different-sized grazers have distinctive effects on plant functional composition of an African savannah

Grazing ungulates play a key role in many ecosystems worldwide and can form diverse assemblages, such as in African savannahs. In many of these ecosystems, present-day ungulate communities are impoverished subsets of once diverse assemblages. While we know that excluding all ungulates from grasslands can exert major effects on both the structure and composition of the vegetation, how different individual ungulate species may have contrasting effects on grassland communities remains poorly understood. Here, we performed a long-term ‘Russian doll’ grazing exclosure experiment in an African savannah to test for the effects of different size classes of grazers on grassland structure and composition. At five sites, grazer species of decreasing size class (ranging from white rhino to scrub hare) were excluded using four fence types, to experimentally create different realized grazer assemblages. The vegetation structure and the grass functional community composition were characterized in 6 different years over a 10-year period. Additionally, animal footprints were counted to quantify the abundance of different ungulate species in each treatment. We found that while vegetation height was mostly driven by total grazing pressure of all species together, ungulate community composition best explained the functional community composition of grasses. In the short term, smaller ungulate species (‘mesoherbivores’) had strongest effects on vegetation composition, by shifting communities towards dominance by species with low specific leaf area and low nutritional value. In the long term, large grazers had stronger but similar effects on the functional composition of the system. Surprisingly, the largest ‘mega-herbivore’, the white rhinoceros, did not have strong effects on the vegetation structure or composition. Synthesis. Our results support the idea that different size classes of grazers have varying effects on the functional composition of grassland plant communities. Therefore, the worldwide decline in the diversity of ungulate species is expected to have (had) major impacts on community composition and functioning of grassland ecosystems, even if total grazing pressure has remained constant, for example, due to replacement by livestock.

Environmental sensing by African trypanosomes

African trypanosomes, which divide their life cycle between mammals and tsetse flies, are confronted with environments that differ widely in temperature, nutrient availability and host responses to infection. In particular, since trypanosomes cannot predict when they will be transmitted between hosts, it is vital for them to be able to sense and adapt to their milieu. Thanks to technical advances, significant progress has been made in understanding how the parasites perceive external stimuli and react to them. There is also a growing awareness that trypanosomes use a variety of mechanisms to exchange information with each other, thereby enhancing their chances of survival.

The South-African Zionist Federation, Share-Club

S. Stern

Safer sex choices among African-American college women

The purpose of this dissertation was to explore and describe the factors that influence the safer sex choices of African-American college women. The pandemic of HIV and the prevalence of other sexually transmitted diseases has disproportionately affected African-American females. As young women enter college they are faced with a myriad of choices. Unprotected sexual exploration is one choice that can lead to deadly consequences. This dissertation explores, through in-depth interviews, the factors associated with the decision to practice or not practice safe sex. ^ The first study describes the factors associated with increased sexual risk taking among African-American college women. Sexual risk taking or sex without a condom was found to be more likely when issues of self or partner pleasure were raised. Participants were also likely to have sexual intercourse without a condom if they desired a long term relationship with their partner. ^ The second study examined safe sex decision making processes among a group of African-American college women. Women were found to employ both emotional and philosophical strategies to determine their safe sex behavior. These strategies range from assessing a partner's physical capabilities and appearance to length of the dating relationship. ^ The third study explores the association between knowledge and risk perception as predictors for safer sex behaviors. Knowledge of HIV/AIDS and other STDs was not found to be a determinant of safer sex behavior. Perception of personal risk was also not highly correlated with consistent safer sex behavior. ^ These studies demonstrate the need for risk-based safer sex education and intervention programs. The current climate of knowledge-based program development insures that women will continue to predicate their decision to practice safer sex on their limited perception and understanding of the risks associated with unprotected sexual behavior. Further study into the emotional and philosophical determinants of sexual behavior is necessary for the realistic design of applicable and meaningful interventions. ^

Prenatal care: A survey of African American women in Houston

The focus of the study was to identify variables that African American women who delivered at a teaching hospital in Houston, Harris County, Texas, between January 12, 1998 and April 24, 1998 perceived to prevent them from receiving adequate prenatal care. The research was based on Aday and Andersen's Framework for the Study of Access to Medical Care. A self-administered questionnaire, using realized and potential access indicators, was developed and administered to 161 African American patients at the study hospital. ^ The objectives of the study were (1) to describe the demographic characteristics of African American women who delivered at a large urban teaching hospital between January 12, 1998 and April 24, 1998; and to determine the relationships between (2) predisposing factors such as age, race, educational level, marital status, family structure, social support and attitude toward prenatal care and prenatal care utilization; (3) enabling factors such as income, employment, insurance status, transportation, appointment, and regular source of care; (4) need factors such as perceived health status, number of past pregnancies, pregnancy occurrence; and (5) the relative importance of predisposing, enabling and need factors as predictors of utilization of prenatal care. The indicators of prenatal care utilization examined included the trimester in which the women initiated prenatal care, number of visits, and numbers and types of services received during pregnancy. Barriers cited included low income and inadequate insurance coverage, problems of transportation and child care, unawareness of pregnancy, delays in the scheduling of appointments, and having too many other problems. ^ The results of the study have implications for well-defined public health promotion campaigns, social support system enhancement, and appointment scheduling reform with an emphasis on prenatal care. ^

Stress and coping in African American grandparents who are raising grandchildren

Over the years, substantial increases have occurred in the number of children being raised by their grandparents. A small number of studies have reported that grandparents raising grandchildren experience an increase in stress due to the demands of caregiving. The primary objectives of this study were to: (1) determine the degree of stress in African American (AA) grandparents who are raising their grandchildren age 12 years or younger; (2) identify the variables pertaining to the demographic characteristics of the grandparent caregiver and characteristics of the caregiving situation; (3) identify the coping strategies reported by AA grandparents; and (4) identify the relative importance of demographic and situational variables pertaining to the grandparent caregiver and caregiving situation, and coping strategies in influencing the degree of stress experienced. ^ An exploratory, descriptive, cross sectional design was used to study stress and coping in 50 AA grandparents who ranged in age from 44–87 years (M = 63.12). Data were collected via one personal interview in January/February 2001 at area senior centers or churches which the grandparent attends in Harris County, Texas. Five home interviews were done as requested by grandparents. ^ The instruments used to measure stress and coping were the Parenting Stress Index developed by Abidin and Folkman and Lazarus' Ways of Coping Questionnaire. Results of the study found that the grandparents is this study were a highly stressed group. Ninety-four percent of the sample demonstrated a “clinically significant” level of stress. Situational variables associated with lower stress levels were use of counseling, use of special school programs such as tutoring and special education, and increased length of caregiving (>5 years). ^ The most frequently used coping strategies overall were seeking social support and positive reappraisal. Six coping strategies were significantly correlated to lower reported stress: positive reappraisal, accepting responsibility, confrontive coping, self-control, planful problem solving, and distancing. ^ The findings from this study have limited generalizability. Nonetheless, this study was useful in adding to the limited amount of literature on AA grandparents who are rearing their grandchildren. The results clearly suggest the need for affordable counseling, support groups, education related to available resources, stress management, and interventions that increase the use of coping strategies found to reduce perceived stress. Future research should investigate levels of stress in AA and other grandparent caregivers longitudinally, as well as focus on stress and coping in grandparents raising grandchildren with special needs. ^

Life, wanderings and labours in Eastern Africa : with an account of the first successful ascent of the equatorial snow mountain, Kilima Njaro, and remarks upon East African slavery

by Charles New, of the late Livingstone search and relief expedition

The Congo Slave State : a protest against the new African slavery ; and an appeal to the public of Great Britain, of the United States, and of the Continent of Europe

by Edmund D. Morel

The new African slavery; or, King Leopold's rule in Africa

by E. D. Morel

Adolescent tobacco use: Studies of prevalence, factorial validity, and factorial invariance between African Americans and Whites

In the last thirty years, increasing efforts have been made to reduce the prevalence of adolescent tobacco use in the United States. Although the prevalence has declined dramatically over the past decade, there are still sharp differences in adolescent smoking-initiation rates across racial/ethnic groups. Large-scale surveys frequently assess smoking-related attitudes, self-efficacy, and intentions to explain the differences in smoking rates between African Americans and Whites. However, there is little agreement about which constructs are significant. Moreover, the psychometric properties of smoking-related attitude, self-efficacy, and intention constructs have not been fully examined. More studies are needed to understand existing patterns of tobacco use and to validate and fully exploit the constructs' relationship to adolescent smoking initiation across racial/ethnic groups. ^ This dissertation reports on a secondary analysis of data from a large multi-ethnic convenience sample of sixth- through eighth-grade students in 22 schools in East Texas and the city of Houston. The specific aims of this dissertation were to (1) describe smoking and alternate tobacco product use rates by race/ethnicity, gender, age, and grade level (Article 1); (2) test the factorial validity of smoking-related attitudes, self-efficacy, and intentions using confirmatory factor analysis techniques (Article 2); and (3) test the factorial invariance of smoking-related attitudes, self-efficacy, and intentions between African Americans and Whites (Article 3). ^ The prevalence findings confirm the disparities in tobacco use among African American, Hispanic, and White adolescents that other surveys have reported (Article 1). This study also demonstrates the usefulness of examining use patterns of not only cigarettes but also alternative tobacco products in younger multiethnic populations, as well as of providing epidemiological data estimates about different phases of smoking. The confirmatory factor analysis provides evidence of construct validity of attitude, self-efficacy, and intention scales for the multiethnic sample (Article 2). Finally, the factorial invariance analyses indicates that some measures representing smoking-related attitudes, self-efficacy, and intentions may not be appropriate for use among both African Americans and Whites (Article 3). Additional research is needed to further our understanding of the patterns and predictors of youth tobacco use initiation. ^

Interventions to reduce sexual risk behavior in African American men

The purpose of this review was to describe characteristics of interventions that have been conducted for African American men and identify similarities and differences between interventions for subpopulations of African American men. Of the 473 studies identified through database searching, 8 studies met the eligibility criteria for this review. Target populations within these studies included heterosexual men, homosexual and bisexual men, persons with mental health problems, and injection and non-injection drug users. Little variation was found in the theories and methods used in interventions for different target populations. However, several different behavioral determinants were addressed within these interventions. Although interventions for drug users generally did not exclude individuals based on sexual orientation, these interventions were able to address HIV sexual risk behavior in heterosexual, homosexual, and bisexual-identified men. Given these findings, multi-faceted approaches to HIV prevention are recommended in order to reduce HIV risk in African American men.^

Sexual orientation and sexual behavior patterns: Evaluation of agreement and variation in a cohort of male, African American drug users in Houston, TX

Background. Sexual orientation and sexual behavior among men have shown disagreement in past studies. The term "on the down low" has been adopted by many to describe "straight" identifying men who have sex with men but do not inform their primary female partner. Methods. This secondary analysis of data collected from the "DASH Project---A Hepatitis B Vaccine Model for HIV Vaccine Trial in Drug Users," assessed sexual behavior patterns among African American drug-using men over time. Using a screener questionnaire to determine sexual orientation and sexual behavior of the men, the study specifically evaluated "straight" identified men who have sex with women only (MSW) to determine what factors were associated with sexual behavior variation to include men during follow-up. The Fisher's Exact Test was used to evaluate the factors. Results. Variation of sexual behavior was highest among "bisexual" identified men followed by "gay" identified men. Fifteen of the original 593 "straight" and MSW men had sexual behavior variation to include men. In the analysis of "straight" and MSW men with variation in sexual behavior compared to those who did not, living on the streets, greater number of sexual partners, trading sex for drugs, and trading sex for money were associated with sexual behavior variation (all p-values <0.01). Conclusions. The factors were only associated when considering the interview when the variation occurred. The same factors at screening were not predictive of sexual behavior variation in the future. Environmental factors, such as living situation, appear to play a role in sexual behavior variations in "straight" and MSW men. ^ Keywords. sexual behavior, sexual orientation, Fisher's Exact Test^