1,207 research outputs found

    Recovery of Amphibian and Reptile Communities During Tropical Secondary Forest Succession

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    The extensive clearing and modification of natural systems from anthropogenic activities is a pressing global concern. Forest habitats and animal communities within forests are among the most highly impacted, globally. Forest destruction has been repeatedly documented as a driver of biodiversity loss. However, little is known about how animal communities respond when altered landscapes are abandoned and left to regenerate into secondary forests. It is thought that the regrowth of secondary forests may help reverse biodiversity loss by restoring habitats to similar conditions as prior to land conversion. Of the forest cover that remains, over half is secondary forest, and in many countries secondary forest cover has been steadily increasing. Therefore, it is important to understand how and if faunal communities recover during secondary forest regeneration. I combined meta-analytic, field-survey-based, and lab-based experimental techniques to determine how amphibians and reptiles respond to habitat change in general, and secondary forest regeneration on landscapes previously cleared for use as pasture. I addressed five specific questions: 1) what are the effects of habitat alteration on amphibians and reptiles?, 2) what are the effects of secondary forest succession on amphibians and reptiles?, 3) what is the relative importance of stochastic and deterministic effects on community assembly during secondary forest succession?, 4) how do amphibian and reptile species composition, probability of occurrence, and species richness change over the course of secondary forest succession?, and 5) is thermal quality of habitat an important mechanism of species response to secondary forest succession? I found that secondary forest has high conservation value for many amphibian and reptile species, environmental changes associated with secondary forest succession have a significant effect on shaping amphibian and reptile community composition, thermal quality is an important mechanism for species response and that strength of response is mediated by species-specific thermal biology. I also highlight the importance of riparian corridors in maintaining species diversity in modified habitats

    Using Simulated Micrometeoroid Impacts to Understand the Progressive Space Weathering of the Surface of Mercury

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    The surfaces of airless bodies such as Mercury are continually modified by space weathering, which is driven by micrometeoroid impacts and solar wind irradiation. Space weathering alters the chemical composition, microstructure, and spectral properties of surface regolith. In lunar and ordinarychondritic style space weathering, these processes affect the reflectance properties by darkening (lowering of reflectance), reddening (increasing reflectance with increasing wavelength), and attenuation of characteristic absorption features. These optical changes are driven by the production of nanophase Febearing particles (npFe). While our understanding of these alteration processes has largely been based on data from the Moon and near-Earth S-type asteroids, the space weathering environment at Mercury is much more extreme. The surface of Mercury experiences a more intense solar wind flux and higher velocity micrometeoroid impacts than its planetary counterparts at 1 AU. Additionally, the composition of Mercurys surface varies significantly from that of the Moon. Most notably, a very low albedo unit has been identified on Mercurys surface, known as the low reflectance material (LRM). This unit is enriched with up to 4 wt.% carbon, likely in the form of graphite, over the local mean. In addition, the surface concentration of Fe across Mercurys surface is low (<2 wt.%) compared to the Moon. Our understanding of how these low-Fe and carbon phases are altered as a result of space weathering processes is limited. Since Fe plays a critical role in the development of space weathering features on other airless surfaces (e.g., npFe), its limited availability on Mercury may strongly affect the space weathering features in surface materials. In order to understand how space weathering affects the chemical, microstructural, and optical properties of the surface of Mercury, we can simulate these processes in the laboratory [7]. Here we used pulsed laser irradiation to simulate the short duration, high temperature events associated with micrometeoroid impacts. We used forsteritic olivine, likely present on the Mercurian surface, with varying FeO contents, each mixed with graphite, in our experiments. We then performed reflectance spectroscopy and electron microscopy to investigate the spectral, chemical, and microstructural changes in these samples

    It's cool to be dominant : social status alters short-term risks of heat stress

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    Climate change has the potential to trigger social change. As a first step towards understanding mechanisms determining the vulnerability of animal societies to rising temperatures, we investigated interactions between social rank and thermoregulation in three arid-zone bird species: fawn-coloured lark (Mirafra africanoides, territorial); African red-eyed bulbul (Pycnonotus nigricans, loosely social) and sociable weaver (Philetairus socius, complex cooperative societies). We assessed relationships between body temperature (Tb), air temperature (Ta) and social rank in captive groups in the Kalahari Desert. Socially dominant weavers and bulbuls had lower mean Tb than subordinate conspecifics, and dominant individuals of all species maintained more stable Tb as Ta increased. Dominant bulbuls and larks tended to monopolise available shade, but dominant weavers did not. Nevertheless, dominantweavers thermoregulated more precisely, despite expending no more behavioural effort on thermoregulation than subordinates. Increasingly unequal risks associated with heat stress may have implications for the stability of animal societies in warmer climates.This study was supported by National Science Foundation Peer Grant no. PGA- 2000003431 to A.E.M., and funding from the DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology to S.J.C. and M.L.T.http://jeb.biologists.org2018-05-30am2017Zoology and Entomolog

    Kindness and competition: Are we striking the right balance in medical education?

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    Many parents could be excused for no longer hoping that their children pursue careers in medicine. Junior medical staff must cope with unforgiving rosters that often include rigorous on-call commitments and night shifts. Coupled with this, they face the emotional challenges of caring for very sick patients and their families. In addition, recent reports of bullying and harassment from the specialty colleges indicate that hospitals continue to be imperfect workplaces

    Medical Biochemistry Without Rote Memorization: Multi-Institution Implementation And Student Perceptions Of A Nationally Standardized Metabolic Map For Learning And Assessment

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    Despite the growing number of patients worldwide with metabolism-related chronic diseases, medical biochemistry education is commonly perceived as focusing on recall of facts irrelevant for patient care. The authors suggest that this focus on rote memorization of pathways creates excessive cognitive load that may interfere with learners’ development of an integrated understanding of metabolic regulation and dysregulation. This cognitive load can be minimized by providing appropriate references during learning and assessment. Biochemistry educators collaborated to develop a medically relevant Pathways of Human Metabolism map (MetMap) that is now being used at many medical schools as a nationally standardized resource during learning and assessments. To assess impact, students from three medical schools were surveyed about its benefits and disadvantages. Responses were obtained from 481 students (84%) and were examined using thematic analysis. Five main themes emerged as perceived benefits of using the MetMap: 1) aids visual and mental organization, 2) promotes deep learning and applied understanding, 3) decreases emphasis on memorization, 4) reduces anxiety on exams, and 5) aids recall. Perceived disadvantages were: 1) fear of under-preparation for licensing exams, 2) overwhelming nature of the map, and 3) reduced motivation for and time spent studying. Results affirm that students perceive use of the MetMap promotes focus on broader metabolic concepts and deep versus surface learning, supporting a shift in cognitive load toward desired goals. Although the long-term impact on learning needs to be further studied, the use of the MetMap represents a step toward open-reference exams that reflect “real world” practice

    The Development and Validation of the Ethical Climate Index for Middle and High Schools

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    One school characteristic that needs to be considered as important in keeping schools safe is school climate. The purposes of this study were to develop and validate an instrument that measures the ethical climate of middle and high schools. To create the School Ethical Climate Index (SECI), we adapted the Ethical Climate Index for graduate and professional school programs to apply to middle and high schools. The SECI measures a school’s sense of community by assessing student and teacher interactions and relationships through the application of five ethical principles: respect for autonomy, nonmaleficence, beneficence, justice, and fidelity. To provide evidence of the SECI’s reliability and validity, we distributed the SECI to 101 teachers and administrators who worked at middle and/or high schools. The reliability coefficients for each of the SECI subscales were greater than .80. Differences between middle and high school teacher and administrator perceptions provided evidence of construct validity. The SECI could be used in school districts to assess areas for school improvement and, thereby, help to reduce school disorder and violence

    Variation in abundance, diversity and composition of coral reef fishes with increasing depth at a submerged shoal in the northern Great Barrier Reef

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    Coral reef fishes often exhibit specific or restricted depth distributions, but the factors (biotic or abiotic) that influence patterns of depth use are largely unknown. Given inherent biological gradients with depth (i.e. light, nutrients, habitat, temperature), it is expected that fishes may exploit certain depths within their environment to seek out more favourable conditions. This study used baited remote underwater video (BRUV) systems to document variation in the taxonomic and functional (trophic and size) structure of a fish assemblage along a shallow to upper-mesophotic depth gradient (13–71 m) at a submerged, offshore shoal in the northern Great Barrier Reef. BRUVs were deployed during two separate time periods (February and August 2017), to separately examine patterns of depth use. Both the relative abundance and diversity of reef fishes declined with depth, and there were pronounced differences in the taxonomic and functional structure of the fish assemblage across the depth gradient. In shallow habitats ( 30 m) was dominated by piscivores and mobile invertivores. Depth and habitat type were also strong predictors for important fisheries species such as coral trout (Plectropomus spp.), emperors (Lethrinus spp.) and trevallies (Carangid spp.). We found limited evidence of temporal changes in depth and habitat use by fishes (including fisheries target species), although recorded temperatures were 4 °C higher in February 2017 compared to August 2017

    First record and massive range extension of Hyalinobatrachium cappellei (Van Lidth de Jeude, 1904) (Anura, Centrolenidae) in Colombia

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    We report the first record of the Banded-limb Glassfrog, Hyalinobatrachium cappellei (Van Lidth de Jeude, 1904), in Colombia based on 2 specimens, 1 each from the municipalities of Cartagena del Chair&amp;aacute; and Solano, department of Caquet&amp;aacute;. The present record represents an additional amphibian species for the country, bringing the known total to 821 species and represents a massive range extension of 1,077 km southwest of the nearest known locality for H. cappellei in Venezuela.&amp;nbsp

    (S)-(−)-Fluorenylethylchloroformate (FLEC) ; preparation using asymmetric transfer hydrogenation and application to the analysis and resolution of amines

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    Fluorenylethylchoroformate (FLEC) is a valuable chiral derivatisation reagent that is used for the resolution of a wide variety of chiral amines. Herein, we describe an improved preparation of (S)-(−)-FLEC using an efficient asymmetric catalytic transfer hydrogenation as the key step. We also demonstrate the application of FLEC as a chiral Fmoc equivalent for chiral resolution, with facile deprotection, of tetrahydroquinaldines, and its capacity for inducing regioselective outcomes in nitration reactions

    Cultivating Hospital Volunteers and Auxiliary Board Leadership: THE NEXT GENERATION

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    In spring 2009, Team Vision accepted the challenge from the VCUHS Hospital Auxiliary Board to assist in increasing the auxiliary volunteer population. After meeting with the Auxiliary Board, Volunteer Services, and John Duvall (team mentor), Team Vision proposed a project that would look more globally at volunteer recruitment, training and placement, and retention.As the project evolved, we also examined how the two organizations could draw on their deep experience and resources not only to develop a robust volunteer population , but to develop and strengthen their own organizations to better define their goals and ensure an Auxiliary Board membership of vitality and longevity
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