601 research outputs found

    Non-Equilibrium Scaling Analysis of Quantum Dots in the Kondo Regime

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    Population Structuring and Patterns of Morphological Variation in Californian Styrax (Styracaceae)

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    Recent studies of genetic variation within and among populations and phylogenetic estimates have provided evidence bearing on the evolutionary history and taxonomy of Styrax in California (S. redivivus). In this paper, data from these studies are further analyzed and integrated with new data from morphology to gain insight into the nature and taxonomic significance of character variation within this species. Six morphological characters thought to be important in the delimitation of infraspecific taxa within S. redivivus were measured on 52 herbarium specimens and analyzed with Pearson correlations and multivariate methods. Five characters are significantly associated with latitude and three characters are significantly multiply correlated with latitude. Permutation tests show a significant association between isozyme allelic variation and latitude. Principal components analysis of the morphological data does not reveal distinct clusters. The distribution of character variation shows that most characters vary along continuous latitudinal clines, and no character exhibits an evident gap in character states. Although principal coordinates and neighbor-joining analyses of the isozyme data, and discriminant function analysis of the morphological data suggest the presence of two groups within S. redivivus, the sum of evidence does not support the delimitation of infraspecific taxa. A taxonomic treatment of S. redivivus, a distribution map of historical Californian collections, and a key distinguishing S. redivivus from related taxa are presented. The species status of S. redivivus is justified, and implications of the data for conservation are discussed

    Letter To The Editor

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    An examination of mining in wilderness logically incompatible yet legally feasible revisiting the Cabinet Mountains mining controversy

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    Staphylococcal Toxic Epidermal Necrolysis: Pathogenesis And Studies On The Subcellular Site Of Action Of Exfoliatin

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    An exfoliating substance elaborated by certain phage Group 2 staphylococci causes toxic epidermal necrolysis. Both in man and in the newborn mouse, intraepidermal cleavage is the predominant histologic feature following exposure to this toxin. Electron microscopic study of sequential biopsy specimens obtained from neonatal mice and from organ cultures of human skin revealed intercellular cleavage and cell separation. The extracellular nature of the exfoliative process was confirmed in several ways: (1) perfused tracers did not penetrate cells during cell separation; (2) cultured cells exposed to high doses of exfoliating fractions demonstrated no signs of injury; and (3) cleaved surfaces examined by scanning electron microscopy and surface replication demonstrated intact plasma membranes. When fractions capable of inducing exfoliation were applied to cultured keratinocytes or fibroblasts, sperm, or lymphocyte suspensions, and to human or mouse skin in vivo, they did not alter the distribution or intensity of concanavalin A binding, ruthenium red staining, pemphigus antibody binding, or HL-A surface antigens. Therefore, while the pathogenesis of staphylococcal toxic epidermal necrolysis involves intercellular cleavage, the molecular cell surface target remains unknown

    Orbital Freezing in FeCr2S4 Studied by Dielectric Spectroscopy

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    Broadband dielectric spectroscopy has been performed on single-crystalline FeCr2S4 revealing a transition into a low-temperature orbital glass phase and on polycrystalline FeCr2S4 where long-range orbital order is established via a cooperative Jahn-Teller transition. The freezing of the orbital moments is revealed by a clear relaxational behavior of the dielectric permittivity, which allows a unique characterization of the orbital glass transition. The orbital relaxation dynamics continuously slows down over six decades in time, before at the lowest temperatures the glass transition becomes suppressed by quantum tunneling.Comment: 4 pages, 4 figure

    PHYLOGENY OF ACRIDOCARPUS-BRACHYLOPHON (MALPIGHIACEAE): IMPLICATIONS FOR TERTIARY TROPICAL FLORAS AND AFROASIAN BIOGEOGRAPHY

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    A major tenet of African Tertiary biogeography posits that lowland rainforest dominated much of Africa in the late Cretaceous and was replaced by xeric vegetation as a response to continental uplift and consequent widespread aridification beginning in the late Paleogene. The aridification of Africa is thought to have been a major factor in the extinction of many African humid-tropical lineages, and in the present-day disparity of species diversity between Africa and other tropical regions. This primarily geologically based model can be tested with independent phylogenetic evidence from widespread African plant groups containing both humid- and xeric-adapted species. We estimated the phylogeny and lineage divergence times within one such angiosperm group, the acridocarpoid clade (Malpighiaceae), with combined ITS, ndhF , and trnL-F data from 15 species that encompass the range of morphological and geographic variation within the group. Dispersal-vicariance analysis and divergence-time estimates suggest that the basal acridocarpoid divergence occurred between African and Southeast Asian lineages approximately 50 million years ago (mya), perhaps after a southward ancestral retreat from high-latitude tropical forests in response to intermittent Eocene cooling. Dispersion of Acridocarpus from Africa to Madagascar is inferred between approximately 50 and 35 mya, when lowland humid tropical forest was nearly continuous between these landmasses. A single dispersal event within Acridocarpus is inferred from western Africa to eastern Africa between approximately 23 and 17 mya, coincident with the widespread replacement of humid forests by savannas in eastern Africa. Although the spread of xeric environments resulted in the extinction of many African plant groups, our data suggest that for others it provided an opportunity for further diversification.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72798/1/j.0014-3820.2002.tb00165.x.pd

    Self-talk and emotions in tennis players during competitive matches

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    A theory-driven classification recently introduced to sport psychology distinguishes between goal-directed self-talk as a controlled type of self-talk, and spontaneous self-talk as an uncontrolled type of selftalk. Based on this classification, the aim of this study was to explore the relationship between self-talk and emotions. To this end, twenty competitive tennis matches were video-recorded. Shortly after the match, the players were confronted with situations from the match and asked to rate the intensity of their emotions experienced, the intensity of their outward emotional reactions, and to report on their self-talk. Multilevel fixed and random effect models showed that the intensity of emotions experienced and outward emotional reactions were lower in instances where players reported solely goal-directed self-talk than in instances where players reported solely spontaneous self-talk. Moreover, in the fixed model, the intensity of emotions experienced was also lower in instances where players reported goal-directed self-talk in conjunction with spontaneous self-talk, compared to instances where players reported solely spontaneous self-talk. Finally, exploratory analyses suggest that these effects are mostly true for negative emotions rather than positive ones. Overall, the findings support the relevance of dualprocess self-talk approaches. These findings encourage players to gain awareness about their emotions through spontaneous self-talk, while they can use goal-directed self-talk for emotion regulation. Lay summary: During a match, most tennis players talk a lot to themselves. This study shows that their self-talk is related to (a) the emotions they experience and (b) the emotions they show to the outside. Specifically, a goal-oriented type of self-talk is related to less intense emotions. IMPLICATIONS FOR PRACTICE Players can gain awareness about their emotional states through spontaneous self-talk. Players can use goal-directed self-talk to proactively and reactively regulate emotions. Video-assisted recall can be helpful to assess and learn to deal with challenging psychological states during sport competitions
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