Dartmouth College

About: Dartmouth College is a education organization based out in Hanover, New Hampshire, United States. It is known for research contribution in the topics: Population & Health care. The organization has 20740 authors who have published 51426 publications receiving 2796969 citations. The organization is also known as: Dartmouth.

Formation of Electron Holes and Particle Energization During Magnetic Reconnection

Abstract: Three-dimensional particle simulations of magnetic reconnection reveal the development of turbulence driven by intense electron beams that form near the magnetic x-line and separatrices. The turbulence collapses into localized three-dimensional nonlinear structures in which the electron density is depleted. The predicted structure of these electron holes compares favorably with satellite observations at Earth's magnetopause. The birth and death of these electron holes and their associated intense electric fields lead to strong electron scattering and energization, whose understanding is critical to explaining why magnetic explosions in space release energy so quickly and produce such a large number of energetic electrons.

A Uniform System for the Annotation of Vertebrate microRNA Genes and the Evolution of the Human microRNAome

Abstract: Although microRNAs (miRNAs) are among the most intensively studied molecules of the past 20 years, determining what is and what is not a miRNA has not been straightforward. Here, we present a uniform system for the annotation and nomenclature of miRNA genes. We show that less than a third of the 1,881 human miRBase entries, and only approximately 16% of the 7,095 metazoan miRBase entries, are robustly supported as miRNA genes. Furthermore, we show that the human repertoire of miRNAs has been shaped by periods of intense miRNA innovation and that mature gene products show a very different tempo and mode of sequence evolution than star products. We establish a new open access database--MirGeneDB ( http://mirgenedb.org )--to catalog this set of miRNAs, which complements the efforts of miRBase but differs from it by annotating the mature versus star products and by imposing an evolutionary hierarchy upon this curated and consistently named repertoire.

Anhedonia, Positive and Negative Affect, and Social Functioning in Schizophrenia

Abstract: This study examines the relationship between anhedonia and the trait dimensions of positive affect (PA) and negative affect (NA) in schizophrenia. The relationship between poor social functioning in schizophrenia and these individual differences in affectivity is also examined. Schizophrenia outpatients (n = 37) and normal controls (n = 15) were assessed at a baseline evaluation and again approximately 90 days later. Consistent with the hypothesized decrease in hedonic capacity in schizophrenia, patients reported significantly greater physical and social anhedonia and less PA than controls. However, the schizophrenia group also reported significantly greater NA and social anxiety than did controls. In support of the dispositional view of these individual differences in affectivity, trait measures demonstrated test-retest reliability, and group differences between the schizophrenia group and controls were stable over the 90-day followup period. Within the schizophrenia group, physical and social anhedonia were comparably negatively correlated with trait PA; however, social but not physical anhedonia was significantly positively correlated with NA and social anxiety. Poor social functioning in the schizophrenia group was associated with greater physical and social anhedonia and greater NA and social anxiety. Alternatively, greater trait PA was related to better social functioning. These findings indicate that schizophrenia is characterized by both low PA and elevated NA and that these affective characteristics are a stable feature of the illness. The results also suggest important links between affect and social functioning in schizophrenia.