462 research outputs found

    A new assemblage of ray-finned fishes (Teleostei) from the Lower Oligocene “Schistes à Meletta” from the Glières plateau, Bornes Massif, eastern France

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    A recently discovered fish assemblage from the “Schistes à Meletta” facies (Lower Oligocene) of the Glières Plateau, Bornes Massif, Haute–Savoie, eastern France is described. The assemblage, comprising specimens ranging from fully-articulated skeletons to isolated scattered ossifications, is composed of Anenchelum cf. glarisianum, Pristigenys sp., Fistularia sp., Caranx cf. glarisianus alongside indeterminate teleosts. This new assemblage greatly increases the fish diversity previously known from the “Schistes à Meletta” of this area. The fauna shows biogeographic affinities with assemblages from the Peritethys domain, in particular from the Helvetic molassic basin and from the Paratethys. The genera identified at the Glières locality are represented today by species living in tropical nearshore environments together with species from the open sea. A possible explanation is that the environment of deposition was rather deep, and that shallow-water fishes were brought in by turbidity currents

    How to Measure Scope Variables when no Metrics Exist : Application to Landscape Quality Measurement and Hedonic Price Evaluation

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    Landscape is an example of a non-market good where no metrics exist to measure its quality. The paper proposes an original methodology to nevertheless estimate scope variables in those circumstances, allowing then to better test if people's willingnesstopay for such good is sensitive to the scope. The methodology is based on techniques developed in the context of multicriteria decision analysis. It is applied to assess the quality of the landscape of several Swiss alpine resorts. This assessment is then used as an explanatory variable in a hedonic price function to explain the rent of apartments and to derive an implicit price of the landscape quality

    Positive Imagery-Based Cognitive Bias Modification as a Web-Based Treatment Tool for Depressed Adults: A Randomized Controlled Trial.

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    Depression is a global health problem requiring treatment innovation. Targeting neglected cognitive aspects may provide a useful route. We tested a cognitive-training paradigm using positive mental imagery (imagery cognitive bias modification, imagery CBM), developed via experimental psychopathology studies, in a randomized controlled trial. Training was delivered via the Internet to 150 individuals with current major depression. Unexpectedly, there was no significant advantage for imagery CBM compared with a closely matched control for depression symptoms as a whole in the full sample. In exploratory analyses, compared with the control, imagery CBM significantly improved anhedonia over the intervention and improved depression symptoms as a whole for those participants with fewer than five episodes of depression and those who engaged to a threshold level of imagery. Results suggest avenues for improving imagery CBM to inform low-intensity treatment tools for depression. Anhedonia may be a useful treatment target for future work

    Scaling of the distribution of fluctuations of financial market indices

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    We study the distribution of fluctuations over a time scale Δt\Delta t (i.e., the returns) of the S&P 500 index by analyzing three distinct databases. Database (i) contains approximately 1 million records sampled at 1 min intervals for the 13-year period 1984-1996, database (ii) contains 8686 daily records for the 35-year period 1962-1996, and database (iii) contains 852 monthly records for the 71-year period 1926-1996. We compute the probability distributions of returns over a time scale Δt\Delta t, where Δt\Delta t varies approximately over a factor of 10^4 - from 1 min up to more than 1 month. We find that the distributions for Δt\Delta t \leq 4 days (1560 mins) are consistent with a power-law asymptotic behavior, characterized by an exponent α3\alpha \approx 3, well outside the stable L\'evy regime 0<α<20 < \alpha < 2. To test the robustness of the S&P result, we perform a parallel analysis on two other financial market indices. Database (iv) contains 3560 daily records of the NIKKEI index for the 14-year period 1984-97, and database (v) contains 4649 daily records of the Hang-Seng index for the 18-year period 1980-97. We find estimates of α\alpha consistent with those describing the distribution of S&P 500 daily-returns. One possible reason for the scaling of these distributions is the long persistence of the autocorrelation function of the volatility. For time scales longer than (Δt)×4(\Delta t)_{\times} \approx 4 days, our results are consistent with slow convergence to Gaussian behavior.Comment: 12 pages in multicol LaTeX format with 27 postscript figures (Submitted to PRE May 20, 1999). See http://polymer.bu.edu/~amaral/Professional.html for more of our work on this are

    Biocatalyzed C-C bond formation for the production of alkaloids

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    Traditional methods of chemical synthesis of alkaloids exhibit various problems such as lack of enantioselectivity, the use of toxic chemical and intermediates, and multiple numbers of synthetic steps. Consequently, various enzymatic methods for the formation of C-C bonds in the alkaloid skeleton have been developed. Herein, we report advances achieved in the enzymatic or chemo-enzymatic synthesis of pharmaceutically important alkaloids that employ three C-C bond forming enzymes: two Pictet-Spenglerases and the oxidative C-C bond forming flavoenzyme Berberine Bridge Enzyme. Protein engineering studies, improving the substrate scope of these enzymes, and thereby leading to the synthesis of non-natural alkaloids possessing higher or newer pharmacological activities, are also discussed. Furthermore, the integration of these biocatalysts with other enzymes, in multi-enzymatic cascades for the enantioselective synthesis of alkaloids, is also reviewed. Current results suggest that these enzymes hold great promise for the generation of C-C bonds in the selective synthesis of alkaloid compounds possessing diverse pharmacological properties

    Mental Imagery-Based Training to Modify Mood and Cognitive Bias in Adolescents: Effects of Valence and Perspective

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    Mental imagery has a powerful impact on emotion and cognitive processing in adults, and is implicated in emotional disorders. Research suggests the perspective adopted in mental imagery modulates its emotional impact. However, little is known about the impact of mental imagery in adolescence, despite adolescence being the key time for the onset of emotional dysfunction. We administered computerised positive versus mixed valence picture-word mental imagery training to male adolescent participants (N = 60, aged 11–16 years) across separate field and observer perspective sessions. Positive mood increased more following positive than mixed imagery; pleasantness ratings of ambiguous pictures increased following positive versus mixed imagery generated from field but not observer perspective; negative interpretation bias on a novel scrambled sentences task was smaller following positive than mixed imagery particularly when imagery was generated from field perspective. These findings suggest positive mental imagery generation alters mood and cognition in male adolescents, with the latter moderated by imagery perspective. Identifying key components of such training, such as imagery perspective, extends understanding of the relationship between mental imagery, mood, and cognition in adolescence
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