Hidden degree of freedom and critical states in a two-dimensional electron gas in the presence of a random magnetic field

We establish the existence of a hidden degree of freedom and the critical states of a spinless electron system in a spatially-correlated random magnetic field with vanishing mean. Whereas the critical states are carried by the zero-field contours of the field landscape, the hidden degree of freedom is recognized as being associated with the formation of vortices in these special contours. It is argued that, as opposed to the coherent backscattering mechanism of weak localization, a new type of scattering processes in the contours controls the underlying physics of localization in the random magnetic field system. In addition, we investigate the role of vortices in governing the metal-insulator transition and propose a renormalization-group diagram for the system under study.Comment: 17 pages, 16 figures; Figs. 1, 7, 9, and 10 have been reduced in quality for e-submissio

The influence of racial factors on psychiatric diagnosis: A review and suggestions for research

Research on race and diagnosis initially focused on black-white differences in depression and schizophrenia. Statistics showing a higher treated prevalence of schizophrenia and a lower prevalence of depression for blacks seemed to support the claim that blacks did not suffer from depression. Others argued, however, that clinicians were misdiagnosing depression in blacks. This article reviews empirical studies of racial differences in individual symptoms and summarizes the evidence on misdiagnosis. It argues that more attention must be paid to resolving two contradictory assumptions made by researchers working in the area of race and diagnostic inference: (1) blacks and whites exhibit symptomatology similarly but diagnosticians mistakenly assume that they are different; (2) blacks and whites display psychopathology in different ways but diagnosticians are unaware of or insensitive to such cultural differences. The article concludes with suggested research directions and a discussion of critical research issues.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44303/1/10597_2004_Article_BF00755677.pd