Hall effect measurements on Bridgman-grown CuInSe2 with sodium.

The presence of sodium, either in the substrate or as a co-evaporant during absorber deposition, has been shown to improve the performance of polycrystalline photovoltaic devices made with Cu(In, Ga)Se(2), as well as the ternary CuInSe(2). Investigations have shown Na or Na compounds deposited on the grain boundaries, but none have been found within intact crystal grains, leading to suggestions that grain boundaries may play a role in the improved performance of the cells. Therefore, in this study, ingots containing large monocrystals of CuInSe(2) have been grown, using a vertical-Bridgman method, from melts that also include a varying quantity of sodium. In order to simulate the conditions under which cells are constructed, a proportion of Se above stoichiometry has been added to some of the melts. Resistivity and Hall effect measurements were then performed on the material after growth. The results show no large change in either resistivity or majority hole concentration in either set of samples, although a slight decrease in the latter value was apparent in the excess Se samples with 0.2 and 0.3 at.% Na additions. No clear trend in hole mobility could be discerned, although an increase was seen with 0.2 at.% Na addition for both samples.

Predictors of neuropsychological performance in HIV positive women.

This study examines predictors of neuropsychological (NP) performance in a community sample of 237 HIV seropositive and seronegative women. Consistent with literature describing the NP sequelae of HIV infection in men, we expected that HIV status would predict poorer NP performance on tests assessing verbal memory, psychomotor speed and motor speed. Multiple regression analyses testing the association between HIV serostatus and NP performance and controlling for predictors including age, ethnicity, education, psychological distress, and drug and alcohol use indicated that HIV serostatus was associated with slowed psychomotor speed. Specifically, AIDS diagnosis and HIV seropositivity predicted poorer performance on tests of psychomotor speed relative to HIV seronegatives. Contrary to expectations, no relationship between HIV serostatus and either motor speed or verbal memory performance emerged. Education, ethnicity, depressive distress, recent exposure to drugs as indexed by toxicology, and alcohol use were also associated with NP performance. Given that the HIV seropositive and seronegative samples differed on a number of demographic and drug use variables, a second series of analyses examining a subset of participants (matched on all key demographic factors) and with no illicit drug use during the past year was also conducted. Results of these analyses were similar to those obtained for the full sample, with AIDS diagnosis and HIV seropositivity predicting psychomotor slowing. To date, little work describing the NP sequelae of HIV infection in women has been conducted. This study provides one of the first descriptions of the NP effects of HIV/AIDS in a largely non-injection drug using community sample of women.

The effects of racial stressors and hostility on cardiovascular reactivity in African American and Caucasian men.

This study examined the effects of race-related stressors and hostility on cardiovascular reactivity in 31 African American and 31 Caucasian men. Participants viewed 3 film excerpts that depicted neutral, anger-provoking (but race-neutral), and racist situations. Participants exhibited significantly greater diastolic blood pressure reactivity to anger-provoking and racist stimuli compared with neutral stimuli. In addition, high hostility was associated with higher recovery systolic and diastolic blood pressure levels after exposure to the films. Although the results failed to confirm previous reports of greater reactivity to racism in African Americans, the findings suggest that diastolic blood pressure levels may remain elevated after exposure to racist stimuli. These results indicate that even indirect exposure to interpersonal conflict elicits significant reactivity, which can persist after exposure to the stressor, especially among high-hostile men.

Psychosocial predictors of first-onset depression in Chinese Americans.

BACKGROUND: This study examines the longitudinal and concurrent risk factors associated with first-onset major depression in a community sample of 1747 Chinese Americans in Los Angeles. METHODS: The relative contributions of demographic, health, psychiatric, psychosocial, and cultural variables were assessed in a series of longitudinal and concurrent hierarchical multivariable analyses. RESULTS: Results of the longitudinal analyses indicated that the risk for experiencing a first major depressive episode at 18-months follow-up was higher for those who initially rated their health as poor, reported higher depressive symptoms, and perceived higher levels of social support. After controlling for prior health and psychiatric and psychosocial status at time 1, the results of the concurrent analyses indicated that the risk for experiencing a first major depressive episode at time 2 was higher for those who rated their health as poor, had at least one other psychiatric disorder, were bilingual, experienced high levels of life stress, and perceived themselves as having low and/or decreased social supports. CONCLUSIONS: The results of this study confirm previous evidence that psychosocial vulnerabilities, including higher acculturation, greater stress exposure and reduced social supports, are important predictors of risk for first-onset depressive episodes. Prevention and treatment implications are addressed, and future directions for research are offered.

HIV-1, cocaine, and neuropsychological performance in African American men.

The purpose of this study was to examine the independent and interactive effects of HIV-1 serostatus and cocaine on neuropsychological (NP) performance in a sample of 237 gay and bisexual urban-dwelling African American men. Consistent with current evidence, it was expected that the greatest neuropsychological performance deficits would be evident (1) in the symptomatic seropositives (SSPs), especially in domains affected by HIV (i.e., memory and psychomotor speed), and on tests that are sensitive to subtle slowing; (2) in those who are recent and frequent cocaine abusers; and (3) in those who are both HIV seropositive and cocaine abusers. Multivariate analyses controlling for age and alcohol use confirmed expectations, with symptomatic seropositives (SSPs) evidencing significantly poorer psychomotor speed than the seronegatives (SNs), and slower reaction time and poorer nonverbal memory than the asymptomatic seropositives (ASPs). Moderate to heavy recent cocaine use was associated with slower psychomotor speed. However, contrary to expectations, no interaction of serostatus and cocaine was noted for any NP domain, and the expected serostatus and cocaine effects on verbal memory and frontal systems were not obtained. Level of alcohol consumption exacerbated the detrimental effects of HIV-1 on a computerized reaction time test which is especially sensitive to subtle slowing. This study provides one of the first descriptions of the neuropsychological effects of HIV-AIDS in a non-injection drug-using community sample of gay and bisexual African American men.

Neuropsychiatric disturbance is associated with executive dysfunction in HIV-1 infection.

Prominent apathy and/or irritability are frequently observed among individuals infected with the human immunodeficiency virus (HIV). Although these symptoms often occur as part of a mood disorder, compelling evidence suggests that they may occur independently of depression in neurologic disease/disorder. The current study examined the prevalence of both apathy and irritability among a sample of HIV-infected individuals and explored the degree to which these neuropsychiatric (NP) phenomena were associated with performance on neuro-cognitive measures thought to be sensitive to the potential CNS effects of HIV-1. Clinician-administered rating scales assessing apathy and irritability were administered to 65 HIV-seropositive (HIV+) and 21 HIV-seronegative (HIV-) participants who also completed a dual-task reaction time paradigm and the Stroop task. NP disturbance was significantly more prevalent among HIV+ participants compared with HIV- controls and was associated with specific neuro-cognitive deficits suggestive of executive dysfunction. Relative to both HIV- controls and to neuro-psychiatrically intact HIV+ participants, those HIV+ individuals with evidence of prominent apathy and/or irritability showed deficits in dual-task, but not single-task, performance and on the interference condition of the Stroop. Unexpectedly, NP disturbance did not show a robust relationship with HIV disease stage. These results suggest that the presence of prominent apathy and/or irritability among HIV+ individuals may signify greater HIV-associated CNS involvement. In HIV/AIDS, the disruption of frontal-subcortical circuits may be a common mechanism causing both executive dysfunction and NP disturbance.

Increased natural killer-cell mobilization and cytotoxicity during marital conflict.

Natural killer (NK) cells are reproducibly mobilized into the circulation in response to intense physical exercise or acute psychological stress, and altered expression of adhesion molecules potentially contributes to NK-cell mobilization. Studies of leukocyte mobilization during acute stress have used psychological stressors which facilitate tight experimental control but have limited applicability to everyday life. We therefore used a laboratory model of marital conflict as an experientially meaningful acute stressor to elucidate relationships among conflict, cardiovascular reactivity, and altered leukocyte phenotype and function. Forty-one ethnically diverse, nondistressed, healthy married couples were asked to discuss a specific problem in their marriage for 15 min. Blood pressure and heart rate were measured before, during, and after the discussion, and blood was remotely drawn at the same time points to quantify numbers of specific leukocyte subsets, NK-cell adhesion molecule expression, and NK cytotoxicity. Couples responded to the conflict task with cardiovascular reactivity; increases in the percentages of circulating NK cells and CD8(+) T cells and decreases in the percentage of circulating CD4(+) T cells; decreases in the percentage of NK cells that express L-selectin; and increases in NK-cell cytotoxicity without a commensurate increase in per-cell cytotoxicity. Rapid downregulation or shedding of L-selectin (CD62L) from NK cells did not contribute to their mobilization during conflict. Instead, CD62L(-) NK cells were mobilized while CD62L(+) NK cells were selectively retained in the vascular marginating pool and/or in extravascular tissue. From a broader perspective, the data support the hypothesis that altered trafficking of specific leukocyte subsets is an integral component of the fight-or-flight response to an acute stressor.

Stress, stress reduction and hypercholesterolemia in African Americans: a review.

Psychological stress may directly contribute to the disproportionately high rates of coronary heart disease morbidity and mortality and its etiologic risk factors in African Americans. Specifically, acute and chronic stress have been shown to raise serum lipids and are associated with clinical coronary events. The mechanisms by which stress contributes to alterations in lipid levels are not fully known, but various pathways (ie, hormonal, dietary, etc) have been implicated. Traditional methods for reducing blood serum lipids include diet, drugs or both. These methods have been criticized because of issues of compliance, side effects, and cost. Because of these limitations, nondrug behavioral methods are recommended by the National Cholesterol Education Program as the first line of prevention and treatment for hypercholesterolemia and other risk factors. Research shows that CHD morbidity and mortality and major risk factors may be modifiable by behavioral intervention. Specifically, the Transcendental Meditation technique, an effective antidote to stress, reduces levels of major CHD risk factors including hypercholesterolemia, as well as blood pressure and smoking. Using an effective stress reduction approach for prevention and treatment of CHD and its risk factors in African Americans may prove to be a valuable asset for this underserved population.

Psychosocial predictors of natural killer cell mobilization during marital conflict.

This study examined how specific emotions relate to autonomic nervous and immune system parameters and whether cynical hostility moderates this relationship. Forty-one married couples participated in a 15-min discussion about a marital problem. Observers recorded spouses' emotional expressions during the discussion, and cardiovascular, neuroendocrine, and immunologic parameters were assessed throughout the laboratory session. Among men high in cynical hostility, anger displayed during the conflict was associated with greater elevations in systolic and diastolic blood pressure, cortisol, and increases in natural killer cell numbers and cytotoxicity. Among men low in cynical hostility, anger was associated with smaller increases in heart rate and natural killer cell cytotoxicity. These findings suggest that models describing the impact of stress on physiology should be refined to reflect the joint contribution of situational and dispositional variables.

Effects of depressed mood versus clinical depression on neuropsychological test performance among African American men impacted by HIV/AIDS.

The utility of self-report measures in identifying those at risk for depressive disorder and the adverse impact of depression versus depressed mood and HIV serostatus on neuropsychological (NP) test performance were examined in a large sample (N = 243) of gay and bisexual African American men. Results indicate high rates of depression relative to recent population estimates, regardless of methodology, but that the use of standard cut-scores for self-report inventories may significantly overestimate psychiatric morbidity. Limited independent effects of serostatus or depression on NP test performance were observed. More importantly, a complex set of adverse effects of depression and its interaction with serostatus which varied according to the methodology used to assess depression were observed. These findings are discussed in light of ongoing controversy regarding the relative influence of depression on neuropsychological functioning among people living with HIV/AIDS.

The African-American Health Project (AAHP): study overview and select findings on high risk behaviors and psychiatric disorders in African American men.

The AAHP investigated the neurobehavioral and psychosocial sequelae of HIV-1 and substance use in urban African American men. A community resident sample of 502 African American men stratified by HIV-1 serostatus, drug use and sexual orientation were recruited. A comprehensive battery of measures of neurobehavioral and health status, lifestyle and psychosocial characteristics were administered to all participants, and a stratified sub-sample of 120 participants were tested using state of the art brain imaging techniques to investigate differences in the functional and neurophysiologic effects of HIV-1 and substance use. An overview of the methodology of the AAHP and results on high risk sexual and substance use behaviors, and psychiatric disorders are presented and discussed. The sample was primarily HIV-negative (63%), heterosexual (49% gay or bisexual) and a high percentage used substances during the past year (56% used drugs and 30% moderate/heavy drinkers). High-risk sexual practices were relatively prevalent, and a high percentage reported a history of STDs and other infections. Finally, 25% had a current psychiatric disorder, with gays/bisexuals and HIV-seropositives evidencing greater psychiatric vulnerability. More research is needed to further explore the apparent greater risk for psychiatric disorders among gay and bisexual men, and to determine whether being African American and lower social class exacerbate this risk.

Behavioral risk factors related to chronic diseases in ethnic minorities.

This article reviews the evidence on 5 risk behaviors: cigarette smoking, dietary intake, being overweight, limited exercise, and alcohol consumption among African Americans, Asian/Pacific Islanders, Latinos, and Native Americans. Although there is little basis for believing that these high-risk behaviors are any less significant as contributors to chronic disease risk in any ethnic group, the limited information available, especially for Asian/Pacific Islanders and Native Americans, indicates that there may be significant within- and between-group differences in the prevalence of these behaviors. Therefore, some of the ethnic group differences in morbidity and mortality for chronic diseases are partly attributable to differences in behavioral risk profiles. Limited basic health behavior information on most ethnic minority groups delay the development of effective health promotion interventions.

Parental and family predictors of behavior problems in inner-city black children.

Studied contributions of maternal psychological distress, family stress load, maternal and family risk factors, and family coping strategies in predicting behavior problems in 441 inner-city black primary-grade children. Results indicated maternal psychological distress and high family stress load were associated with high child behavior problems. Family coping strategies offered no protection against risk, while coping with life difficulties by reframing them was detrimental to child behavioral adjustment. Active help-seeking strategies (i.e., family mobilization, acquiring social supports) served to moderate the effects of maternal psychological distress and family risk attributes for boys, but exacerbated the effects of dysfunctional maternal social and psychiatric histories for girls. Implications for understanding vulnerability and resilience in inner-city black children and recommendations for future research are discussed.

Cardiovascular reactivity with caffeine and stress in black and white normotensive females.

Forty-eight healthy, young, normotensive black and white women, half with and half without a parental history of hypertension, were studied using a double-blind, randomized design. Systolic (SBP) and diastolic (DBP) blood pressures and heart rate (HR) were recorded in response to 250 mg of caffeine vs placebo (3 mg) during rest and during a stressful mental arithmetic task. Results indicated no racial or parental history differences in response to caffeine or to stress. Surprisingly, our female subjects evidenced a small drop in SBP (1 mm Hg) and a decline in HR (5 bpm), and, as expected, they demonstrated a rise in DBP of 6 mm Hg in response to caffeine. The effects of caffeine on SBP and HR were contingent on the experimental condition such that the difference in SBP and HR between the high vs low dose of caffeine was significant only under the caffeine plus psychological stress condition. These effects were only partially consistent with those previously observed in males. Previous evidence of significantly greater DBP pressor effects when caffeine is consumed under stressful conditions was confirmed. However, in this study, the caffeine alone condition had little effect on SBP reactivity and promoted a decrease in HR reactivity. The results are discussed in relation to previous research on males, and recommendations for future research are offered.

Hypertension in blacks: psychosocial and biological perspectives.

The extraordinarily high rate of hypertension in blacks remains a significant public health issue in most industrialized societies. Research has focused on the investigation of racial differences in biological, nutritional, behavioural and psychological, and social factors in an effort to identify the causes of this high morbidity rate. Thus far, research suggests important racial differences in renal functioning, particularly in sodium metabolism and plasma renin activity, as well as potassium intake and sodium:potassium ratio. Behavioral factors such as anger-coping style and John Henryism, and social factors such as socioeconomic status, socioecological stress, social support, urban-rural residence, and family interaction patterns have also been identified as potential contributors. Finally, emerging research paradigms such as laboratory stress reactivity and 24-h ambulatory monitoring of blood pressure may provide promising leads about the interaction between these effects and hypertension in black populations.

Impact of caffeine and psychological stress on blood pressure in black and white men.

The purpose of this study was to examine the effects of caffeine and psychological stress on systolic blood pressure (SBP) and heart rate (HR) in 40 healthy Black and White male regular coffee drinkers. Half the subjects had a positive family history of hypertension (FH+), and half did not. The effects of 250 mg of caffeine versus placebo (3 mg) in decaffeinated coffee were compared in a within-subject, double-blind, cross-over design. SBP and HR were measured at rest, after caffeine ingestion, during mental arithmetic stress, and during recovery. Results confirmed previous findings with White men that a moderate dose of caffeine produced significant increases in SBP and little effect on HR and that the pressor effects of caffeine and stress combined additively. Contrary to expectations, no overall race or family history differences in SBP levels or in SBP reactivity were observed. FH+ Blacks, however, evidenced slower SBP recovery than Whites. Whites evidenced higher overall HR levels than blacks, but this difference was not specific to caffeine or to mental stress. Mechanisms of racial differences in reactivity underlying differential risk for hypertension are discussed, as well as the utility of caffeine as a pharmacologic probe for such differences.

Psychophysiological reactivity to mental arithmetic stress in black and white normotensive men.

Racial differences in physiological responses to a behavioral stressor were examined. Thirty-four Black and 42 White male normotensives 34 to 55 years old (mean age = 43.01 years) performed a mental arithmetic task while blood pressure, heart rate, and skin conductance were recorded. Compared to Whites, Blacks had significantly higher baseline diastolic blood pressure (77.93 mm Hg vs. 73.11 mm Hg) and lower skin conductance levels (11.08 microS vs. 12.25 microS). These effects persisted during performance of the mental arithmetic task. However, when baseline differences were covaried, there were no significant physiological effects associated with the task. Analysis of changes in response levels from baseline revealed a nonsignificant trend for Whites to show greater increases in systolic blood pressure than Blacks. There were no significant race or family history effects. Further, task performance did not influence the outcome. Failure to demonstrate greater cardiovascular reactivity in Blacks and all men with a positive family history of hypertension is discussed with regard to possible "survivor effects" and methodologic limitations.