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Nonlinear simulations of sawteeth and related energetic particle transport are carried out using the kinetic/magnetohydrodynamic (MHD) hybrid code M3D-K. MHD simulations show repeated sawtooth cycles for a model tokamak equilibrium. Furthermore, test particle simulations are carried out to study the energetic particle transport due to a sawtooth crash. The results show that energetic particles are redistributed radially in the plasma core, depending on pitch angle and energy. For trapped particles, the redistribution occurs for particle energy below a critical value in agreement with existing theories. For co-passing particles, the redistribution is strong with little dependence on particle energy. In contrast, the redistribution level of counter-passing particles decreases with increasing particle energy. [ABSTRACT FROM AUTHOR]

A set of scalar variables and projection operators for the vector momentum and magnetic field evolution equations is presented that has several unique and desirable properties, making it a preferred system for solving the magnetohydrodynamic equations in a torus with a strong toroidal magnetic field. A “weak form” of these equations is derived that explicitly conserves energy and is suitable for a Galerkin finite element formulation provided the basis elements have C1 continuity. Systems of reduced equations are discussed, along with their energy conservation properties. An implicit time advance is presented that adds diagonally dominant self-adjoint energy terms to the mass matrix to obtain numerical stability. [ABSTRACT FROM AUTHOR]

A potential explanation for the finding that disadvantaged minority status is associated with a lower lifetime risk for depression is that individuals from minority ethnic groups may be less likely to endorse survey questions about depression even when they have the same level of depression. We examine this possibility using a nonparametric item response theory approach to assess differential item functioning (DIF) in a national survey of psychiatric disorders, the National Comorbidity Survey. Of 20 questions used to assess depression symptoms, we found evidence of DIF in 3 questions when comparing non-Hispanic blacks with non-Hispanic whites and in 3 questions when comparing Hispanics with non-Hispanic whites. However, removal of the questions with DIF did not alter the relative prevalence of depression between ethnic groups. Ethnic differences do exist in response to questions concerning depression, but these differences do not account for the finding of relatively low prevalence of depression among minority groups. [ABSTRACT FROM AUTHOR]

Objectives: While lower socioeconomic status (SES) is related to higher risk for alcohol dependence, minority race-ethnicity is often associated with lower risk. This study attempts to clarify the nature and extent of social inequalities in alcohol dependence by investigating the effects of SES and race-ethnicity on the development of alcohol dependence following first alcohol use. Design: Cross-sectional analysis of data from the National Epidemiologic Survey on Alcohol and Related Conditions (n = 43093). Survival analysis was used to model alcohol dependence onset according to education, race-ethnicity and their interaction. Setting: United States, 2001-2. Results: Compared with non-Hispanic white people, age-adjusted and sex-adjusted risks of alcohol dependence were lower among black people (odds ratio (OR) = 0.70, 95% confidence interval (CI) = 0.63 to 0.78), Asians (OR = 0.65, CI = 0.49 to 0.86) and Hispanics (OR = 0.68, CI = 0.58 to 0.79) and higher among American Indians (OR = 1.37, CI = 1.09 to 1.73). Individuals without a college degree had higher risks of alcohol dependence than individuals with a college degree or more; however, the magnitude of risk varied significantly by race-ethnicity (χ² for the interaction between education and race- ethnicity = 19.7, df = 10, p = 0.03); odds ratios for less than a college degree were 1.12, 1.46, 2.24, 2.35 and 10.99 among Hispanics, white people, black people, Asians, and American Indians, respectively. There was no association between education and alcohol dependence among Hispanics. Conclusions: Race-ethnicity differences in the magnitude of the association between education and alcohol dependence suggest that aspects of racial-ethnic group membership mitigate or exacerbate the effects of social adversity. [ABSTRACT FROM AUTHOR]

Although previous research has consistently documented that immigrants to the United States have better mental health than US natives, little is known about why this difference occurs. DSM-IV anxiety, mood, impulse control, and substance use disorders were assessed in a nationally representative survey of the US household population, the National Comorbidity Survey Replication. Differences in risk for disorder between immigrants (N = 299) and 5124 natives (N = 5124) were examined using discrete time survival models. Differences were estimated by generation, age of immigration, and duration of residence in the United States. Immigrants had lower lifetime risk of disorder than natives (OR = 0.7; 95% CI, 0.5-0.9). Risk was equally large for natives who were children of immigrants as for natives of subsequent generations. For mood and impulse control disorders, risk equal to that of natives was also found among immigrants who arrived in the United States as children (12 years of age or younger). Immigrants had lower risk than natives prior to arrival in the United States, but there was a trend toward equalization of risk with longer duration of residence in the United States. Differences in risk for disorder emerge within a single generation following immigration, consistent with a strong effect of environmental factors on changes in risk among immigrant populations. This pattern is consistent with either of two causal processes, one involving early socialization in the United States and the other involving postmigration experiences among immigrants who arrive in the United States as adults. [ABSTRACT FROM AUTHOR]

BACKGROUND: Recent research in the United States has demonstrated striking health disparities across ethnic groups. Despite a longstanding interest in ethnic disadvantage in psychiatric epidemiology, patterns of psychiatric morbidity across ethnic groups have never been examined in a nationally representative sample. METHOD: Ethnic differences in psychiatric morbidity are analyzed using data from the National Comorbidity Survey (NCS). The three largest ethnic groups in the United States--Hispanics, Non-Hispanic Blacks and Non-Hispanic Whites were compared with respect to lifetime risk and persistence of three categories of psychiatric disorder: mood disorder, anxiety disorder, and substance use disorder. RESULTS: Where differences across ethnic groups were found in lifetime risk, socially disadvantaged groups had lower risk. Relative to Non-Hispanic Whites, Hispanics had lower lifetime risk of substance use disorder and Non-Hispanic Blacks had lower lifetime risk of mood, anxiety and substance use disorders. Where differences were found in persistence of disorders, disadvantaged groups had higher risk. Hispanics with mood disorders were more likely to be persistently ill as were Non-Hispanic Blacks with respect to both mood disorders and anxiety disorders. Closer examination found these differences to be generally consistent across population subgroups. CONCLUSIONS: Members of disadvantaged ethnic groups in the United States do not have an increased risk for psychiatric disorders. Members of these groups, however, do tend to have more persistent disorders. Future research should focus on explanations for these findings, including the possibility that these comparisons are biased, and on potential means of reducing the disparity in persistence of disorders across ethnic groups. [ABSTRACT FROM AUTHOR]

This article examines a meeting of biomedicine and Traditional Chinese Medicine (TCM) in the context of a psychiatry department in a Japanese national medical school. The meeting is explored through stories of four individuals, the professor of the department and three Chinese physicians studying as exchange students. Global structures of medical authority are revealed in the way each participant follows a different trajectory through this space, positioning themselves by virtue of the medical epistemologies they embody. The particular geography of this meeting between systems allowed for a productive synthesis of diagnostic techniques, quite different from the more common therapeutic syntheses. This synthesis is particularly important for contemporary psychiatry because of its ability to attend to dimensional as opposed to categorical aspects of mental health. [ABSTRACT FROM AUTHOR]