2,254 research outputs found

    ¿Está afectando la actividad turística creciente a la distribución o al número de parejas reproductoras de una pequeña colonia de halcón de Eleonora?

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    Human disturbance is a common threat for species of conservation concern such as the Eleonora’s Falcon. This paper shows that the rise in tourist presence from 1992 to 2000 has not affected the overall number of breeding pairs or their productivity in a small archipelago of the western Mediterranean (Columbretes Islands). However, the increasing tourist activity has coincided with a shift in the degree of occupancy on two islands within the archipelago, favouring that with a lower human presence close to colonies. Several conservation actions are reported and suggested, aimed at both testing and preventing the role of human presence as a factor influencing long–term colony persistence and growth.Las perturbaciones de origen antrópico son un factor de amenaza común para especies vulnerables como el halcón de Eleonora. El presente artículo muestra que el incremento de la presencia humana en un archipiélago del Mediterráneo occidental (islas Columbretes), durante el periodo 1992–2000, no ha afectado ni al número de parejas nidificantes ni a su productividad. Sin embargo, dicho incremento de la actividad turística ha coincidido con un cambio en el nivel de ocupación de dos islas del archipiélago, favoreciendo a la isla menos frecuentada por embarcaciones turísticas. Se sugieren algunas medidas de gestión que pueden servir para comprobar si las visitas turísticas pueden influir en el mantenimiento y crecimiento de la colonia a largo plazo, así como para prevenir estos posibles efectos

    Cambios a largo plazo en la riqueza de especies en una comunidad de aves nidificantes en un pequeño archipiélago mediterráneo

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    We analyzed the pattern of species richness changes in a bird–breeding bird community on a small western Mediterranean archipelago (Columbretes Islands) over a 40–year period (1964–2003). The aim of this study was to qualitatively account for the relative roles of local and regional factors in shaping the community. As expected, we found that regional factors (at the metapopulation spatial scale) increased diversity whereas local factors (i.e. ecological) probably prevented further increases in diversity. We found that the archipelago gained four new species (two seabirds and two falconids) during the study period, whereas no extinctions were recorded. The community seems partially or completely closed to some groups of species (e.g. small–sized birds such as passerines and storm–petrels), probably owing to predatory exclusion by Eleonora falcons (Falco eleonorae). As newly arrived species have breeding calendars that do not fully overlap with those of resident species, competition for space in a rather saturated area is prevented. Preservation of rare species which increase gamma (regional) diversity rather than alpha diversity with common species should be the main local conservation goal.Este trabajo analiza los patrones de cambio en la riqueza de especies en una comunidad de aves nidificantes de un pequeño archipiélago mediterráneo (las islas Columbretes, Castellón) durante un periodo de 40 años (1964–2003). El estudio pretende valorar cualitativamente la influencia relativa de los factores locales y regionales. Como se esperaba, se encontró que los factores regionales (a la escala espacial de la metapoblación) aumentaron la diversidad, mientras que los factores ecológicos locales evitaron mayores incrementos. El archipiélago ganó cuatro especies durante el periodo de estudio (dos aves marinas y dos falcónidos), mientras que no se produjo ninguna extinción. La comunidad parece parcial o totalmente cerrada a ciertos grupos de especies, tales como las aves de pequeña talla (p.ej. Paseriformes y paíños) probablemente debido a la depredación excluyente por parte de los halcones de Eleonor (Falco eleanorae). Dado que las especies que son colonizadoras recientes tienen calendarios de cría que no se solapan completamente con los de las especies residentes, se evita la competencia por el espacio de cría en un área bastante saturada. La principal meta conservacionista debe ser la protección de las especies raras, que incrementan la diversidad gamma (regional), más que la diversidad alpha de las especies comunes

    Developing a Research Mentorship Program: The American Society of Pediatric Nephrology's Experience

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    Background: Most pediatric nephrologists work in academia. Mentor-mentee relationships provide support and guidance for successful research career. Mentorship program implementation is valuable in medical fields for providing research opportunities to young faculty. Methods: The American Society of Pediatric Nephrology (ASPN) established a research mentorship program to (a) assist with matching of appropriate mentor-mentee dyads and (b) establish metrics for desirable mentor-mentee outcomes with two independent components: (1) the grants review workshop, a short-term program providing mentor feedback on grant proposals, and (2) the longitudinal program, establishing long-term mentor-mentee relationships. Regular surveys of both mentors and mentees were reviewed to evaluate and refine the program. Results: Twelve mentees and 17 mentors participated in the grant review workshop and 19 mentees were matched to mentors in the longitudinal program. A review of NIH RePORTER data indicated that since 2014, 13 NIH grants have been awarded. Mentees in the longitudinal program reported that the program helped most with identifying an outside mentor, improving grant research content, and with general career development. Mentors perceived themselves to be most helpful in assisting with overall career plans. Email communications were preferred over phone or face-to-face communications. Mentees endorsed strong interest in staying in touch with their mentors and 100% of mentors expressed their willingness to serve in the future. Conclusion: This mentorship program was initiated and supported by a relatively small medical society and has shown early success in cultivating mentoring relationships for a future generation of clinician-scientists

    Dynamical instabilities of Bose-Einstein condensates at the band-edge in one-dimensional optical lattices

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    We report on experiments that demonstrate dynamical instability in a Bose-Einstein condensate at the band-edge of a one-dimensional optical lattice. The instability manifests as rapid depletion of the condensate and conversion to a thermal cloud. We consider the collisional processes that can occur in such a system, and perform numerical modeling of the experiments using both a mean-field and beyond mean-field approach. We compare our numerical results to the experimental data, and find that the Gross-Pitaevskii equation is not able to describe this experiment. Our beyond mean-field approach, known as the truncated Wigner method, allows us to make quantitative predictions for the processes of parametric growth and thermalization that are observed in the laboratory, and we find good agreement with the experimental results.Comment: v2: Added several reference

    Laser treatment in diabetic retinopathy

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    Diabetic retinopathy is a leading cause of visual impairment and blindness in developed countries due to macular edema and proliferative diabetic retinopathy (PDR). For both complications laser treatment may offer proven therapy: the Diabetic Retinopathy Study demonstrated that panretinal scatter photocoagulation reduces the risk of severe visual loss by >= 50% in eyes with high-risk characteristics. Pan-retinal scatter coagulation may also be beneficial in other PDR and severe nonproliferative diabetic retinopathy (NPDR) under certain conditions. For clinically significant macular edema the Early Treatment of Diabetic Retinopathy Study could show that immediate focal laser photocoagulation reduces the risk of moderate visual loss by at least 50%. When and how to perform laser treatment is described in detail, offering a proven treatment for many problems associated with diabetic retinopathy based on a high evidence level. Copyright (c) 2007 S. Karger AG, Basel

    A Multifaceted Mathematical Approach for Complex Systems

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    Applied mathematics has an important role to play in developing the tools needed for the analysis, simulation, and optimization of complex problems. These efforts require the development of the mathematical foundations for scientific discovery, engineering design, and risk analysis based on a sound integrated approach for the understanding of complex systems. However, maximizing the impact of applied mathematics on these challenges requires a novel perspective on approaching the mathematical enterprise. Previous reports that have surveyed the DOE's research needs in applied mathematics have played a key role in defining research directions with the community. Although these reports have had significant impact, accurately assessing current research needs requires an evaluation of today's challenges against the backdrop of recent advances in applied mathematics and computing. To address these needs, the DOE Applied Mathematics Program sponsored a Workshop for Mathematics for the Analysis, Simulation and Optimization of Complex Systems on September 13-14, 2011. The workshop had approximately 50 participants from both the national labs and academia. The goal of the workshop was to identify new research areas in applied mathematics that will complement and enhance the existing DOE ASCR Applied Mathematics Program efforts that are needed to address problems associated with complex systems. This report describes recommendations from the workshop and subsequent analysis of the workshop findings by the organizing committee

    Intestinal dysbiosis in preterm infants preceding necrotizing enterocolitis: a systematic review and meta-analysis

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    Background Necrotizing enterocolitis (NEC) is a catastrophic disease of preterm infants, and microbial dysbiosis has been implicated in its pathogenesis. Studies evaluating the microbiome in NEC and preterm infants lack power and have reported inconsistent results. Methods and results Our objectives were to perform a systematic review and meta-analyses of stool microbiome profiles in preterm infants to discern and describe microbial dysbiosis prior to the onset of NEC and to explore heterogeneity among studies. We searched MEDLINE, PubMed, CINAHL, and conference abstracts from the proceedings of Pediatric Academic Societies and reference lists of relevant identified articles in April 2016. Studies comparing the intestinal microbiome in preterm infants who developed NEC to those of controls, using culture-independent molecular techniques and reported α and β-diversity metrics, and microbial profiles were included. In addition, 16S ribosomal ribonucleic acid (rRNA) sequence data with clinical meta-data were requested from the authors of included studies or searched in public data repositories. We reprocessed the 16S rRNA sequence data through a uniform analysis pipeline, which were then synthesized by meta-analysis. We included 14 studies in this review, and data from eight studies were available for quantitative synthesis (106 NEC cases, 278 controls, 2944 samples). The age of NEC onset was at a mean ± SD of 30.1 ± 2.4 weeks post-conception (n = 61). Fecal microbiome from preterm infants with NEC had increased relative abundances of Proteobacteria and decreased relative abundances of Firmicutes and Bacteroidetes prior to NEC onset. Alpha- or beta-diversity indices in preterm infants with NEC were not consistently different from controls, but we found differences in taxonomic profiles related to antibiotic exposure, formula feeding, and mode of delivery. Exploring heterogeneity revealed differences in microbial profiles by study and the target region of the 16S rRNA gene (V1-V3 or V3-V5). Conclusions Microbial dysbiosis preceding NEC in preterm infants is characterized by increased relative abundances of Proteobacteria and decreased relative abundances of Firmicutes and Bacteroidetes. Microbiome optimization may provide a novel strategy for preventing NEC

    Hybrid Newton-type method for a class of semismooth equations

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    In this paper, we present a hybrid method for the solution of a class of composite semismooth equations encountered frequently in applications. The method is obtained by combining a generalized finite-difference Newton method to an inexpensive direct search method. We prove that, under standard assumptions, the method is globally convergent with a local rate of convergence which is superlinear or quadratic. We report also several numerical results obtained applying the method to suitable reformulations of well-known nonlinear complementarity problem

    Finite Temperature Models of Bose-Einstein Condensation

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    The theoretical description of trapped weakly-interacting Bose-Einstein condensates is characterized by a large number of seemingly very different approaches which have been developed over the course of time by researchers with very distinct backgrounds. Newcomers to this field, experimentalists and young researchers all face a considerable challenge in navigating through the `maze' of abundant theoretical models, and simple correspondences between existing approaches are not always very transparent. This Tutorial provides a generic introduction to such theories, in an attempt to single out common features and deficiencies of certain `classes of approaches' identified by their physical content, rather than their particular mathematical implementation. This Tutorial is structured in a manner accessible to a non-specialist with a good working knowledge of quantum mechanics. Although some familiarity with concepts of quantum field theory would be an advantage, key notions such as the occupation number representation of second quantization are nonetheless briefly reviewed. Following a general introduction, the complexity of models is gradually built up, starting from the basic zero-temperature formalism of the Gross-Pitaevskii equation. This structure enables readers to probe different levels of theoretical developments (mean-field, number-conserving and stochastic) according to their particular needs. In addition to its `training element', we hope that this Tutorial will prove useful to active researchers in this field, both in terms of the correspondences made between different theoretical models, and as a source of reference for existing and developing finite-temperature theoretical models.Comment: Detailed Review Article on finite temperature theoretical techniques for studying weakly-interacting atomic Bose-Einstein condensates written at an elementary level suitable for non-experts in this area (e.g. starting PhD students). Now includes table of content
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