167 research outputs found

    Cheetah (Acinonyx jubatus) mortality and survival in fenced reserves as part of a managed metapopulation across South Africa

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    Large carnivores require expansive habitat to meet their life history needs making them vulnerable to the loss and fragmentation of natural habitat. This, in addition to human persecution has led to substantial population and range reductions of most of the world’s large carnivores over the past century. Cheetahs are no exception, occupying only 12% of their historic range in South Africa. Reintroduction programs have attempted to re-establish cheetahs to parts of this historic range, and increasingly the potential exists for their conservation in smaller fenced game reserves. However, this requires managers to maintain demographic and genetic diversity. In 2011, the Endangered Wildlife Trust initiated a project which coordinates movements between reserves using a metapopulation framework. This coordinated management approach is still in its infancy and little data exist on how reintroduction success varies amongst individuals and reserves. This study aims to examine the causes of mortality and the factors influencing cheetah survival on 20 reserves using individual life history records from 1993-2018. We assessed demographic, environmental, and management factors that are predicted to influence cheetah survival using a Cox proportional hazard model. Predation, mostly by lions (Panthera leo) accounted for 39% of known mortalities. However, the presence of spotted hyena (Crucota crucuta) posed the greatest threat to survival. Contrary to my prediction, translocation improved survival when controlling for age. Survival has also improved with time since the coordinated metapopulation approach was initiated in 2011. We created a nomogram which can be used by practitioners to predict cheetah survival within the metapopulation. Our study shows the importance of monitoring reintroduction efforts and encourages similar methods be used for other species of conservation concern that are managed within a metapopulation framework

    Improvements in hover display dynamics for a combat helicopter

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    This paper describes a piloted simulation conducted on the NASA Ames Vertical Motion Simulator. The objective of the experiment was to investigate the handling qualities benefits attainable using new display law design methods for hover displays. The new display laws provide improved methods to specify the behavior of the display symbol that predicts the vehicle's ground velocity in the horizontal plane; it is the primary symbol that the pilot uses to control aircraft horizontal position. The display law design was applied to the Apache helmet-mounted display format, using the Apache vehicle dynamics to tailor the dynamics of the velocity predictor symbol. The representations of the Apache vehicle used in the display design process and in the simulation were derived from flight data. During the simulation, the new symbol dynamics were seen to improve the pilots' ability to maneuver about hover in poor visual cuing environments. The improvements were manifested in pilot handling qualities ratings and in measured task performance. The paper details the display design techniques, the experiment design and conduct, and the results

    Five decades of radioglaciology

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    Radar sounding is a powerful geophysical approach for characterizing the subsurface conditions of terrestrial and planetary ice masses at local to global scales. As a result, a wide array of orbital, airborne, ground-based, and in situ instruments, platforms and data analysis approaches for radioglaciology have been developed, applied or proposed. Terrestrially, airborne radar sounding has been used in glaciology to observe ice thickness, basal topography and englacial layers for five decades. More recently, radar sounding data have also been exploited to estimate the extent and configuration of subglacial water, the geometry of subglacial bedforms and the subglacial and englacial thermal states of ice sheets. Planetary radar sounders have observed, or are planned to observe, the subsurfaces and near-surfaces of Mars, Earth's Moon, comets and the icy moons of Jupiter. In this review paper, and the thematic issue of the Annals of Glaciology on ‘Five decades of radioglaciology’ to which it belongs, we present recent advances in the fields of radar systems, missions, signal processing, data analysis, modeling and scientific interpretation. Our review presents progress in these fields since the last radio-glaciological Annals of Glaciology issue of 2014, the context of their history and future prospects

    Gpr37l1 Modulates Seizure Susceptibility: Evidence from Mouse Studies and Analyses of a Human Gpr37l1 Variant

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    Progressive myoclonus epilepsies (PMEs) are disorders characterized by myoclonic and generalized seizures with progressive neurological deterioration. While several genetic causes for PMEs have been identified, the underlying causes remain unknown for a substantial portion of cases. Here we describe several affected individuals from a large, consanguineous family presenting with a novel PME in which symptoms begin in adolescence and result in death by early adulthood. Whole exome analyses revealed that affected individuals have a homozygous variant in GPR37L1 (c.1047G \u3e T [Lys349Asn]), an orphan G protein-coupled receptor (GPCR) expressed predominantly in the brain. In vitro studies demonstrated that the K349N substitution in Gpr37L1 did not grossly alter receptor expression, surface trafficking or constitutive signaling in transfected cells. However, in vivo studies revealed that a complete loss of Gpr37L1 function in mice results in increased seizure susceptibility. Mice lacking the related receptor Gpr37 also exhibited an increase in seizure susceptibility, while genetic deletion of both receptors resulted in an even more dramatic increase in vulnerability to seizures. These findings provide evidence linking GPR37L1 and GPR37 to seizure etiology and demonstrate an association between a GPR37L1 variant and a novel progressive myoclonus epilepsy

    A Long-Term Vision for an Ecologically Sound Platte River

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    The Platte River extends about 310 mi (499 km) from North Platte, Nebraska, to its terminus at the Missouri River confluence near Plattsmouth, Nebraska. The Platte River Valley is a continentally significant ecosystem that serves as a major stopover for migratory waterbirds in the Central Flyway including the endangered Whooping Crane (Grus americana) and \u3e1 million Sandhill Cranes (Antigone canadensis) at the peak of spring migration. However, the Platte River Valley also supports a great diversity of avifauna including grassland breeding birds, native stream fish, vascular plants, herpetofauna, mammals, pollinators, and aquatic macroinvertebrates. Despite ongoing conservation efforts since the mid-1970s the ecosystem remains largely conservation dependent and an increasing number of species across taxa are being considered at risk of regional extirpation or outright extinction. However, given the attention provided to conservation in the Platte River Valley and the need to maintain ecologically functional stopover sites in the Central Flyway, there is a great opportunity to create a resilient refugium for biodiversity conservation in the central Great Plains. To that end we convened a working group of \u3e18 individuals representing \u3e9 organizations including representatives from non-profit conservation organizations, universities, and state and federal natural resource agencies to develop a long-term vision for an ecologically sound Platte River Valley (PRV). We met in groups of varying size for \u3e170 hours throughout a more than 3-year period and developed conservation priorities and objectives using a landscape design process. Landscape design is an interdisciplinary conservation planning process that incorporates components of landscape ecology and social dimensions of natural resources with the explicit intention of improving conservation implementation.https://digitalcommons.unl.edu/zeabook/1128/thumbnail.jp

    Environmental Influences on Growth and Reproduction of Invasive Commelina benghalensis

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    Commelina benghalensis (Benghal dayflower) is a noxious weed that is invading agricultural systems in the southeastern United States. We investigated the influences of nutrition, light, and photoperiod on growth and reproductive output of C. benghalensis. In the first experimental series, plants were grown under high or low soil nutrition combined with either full light or simulated shade. Lowered nutrition strongly inhibited vegetative growth and aboveground spathe production. Similar but smaller effects were exerted by a 50% reduction in light, simulating conditions within a developing canopy. In the second series of experiments, C. benghalensis plants were exposed to different photoperiod conditions that produced short- and long-day plants growing in similar photosynthetic periods. A short-day photoperiod decreased time to flowering by several days and led to a 40 to 60% reduction in vegetative growth, but reproduction above and below ground was unchanged. Collectively, the results indicate that (1) fertility management in highly weathered soils may strongly constrain competitiveness of C. benghalensis; (2) shorter photoperiods will limit vegetative competitiveness later in the growing seasons of most crops; and (3) the high degree of reproductive plasticity and output possessed by C. benghalensis will likely cause continual persistence problems in agricultural fields

    Paxillin Dynamics Measured during Adhesion Assembly and Disassembly by Correlation Spectroscopy

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    Paxillin is an adaptor molecule involved in the assembly of focal adhesions. Using different fluorescence fluctuation approaches, we established that paxillin-EGFP is dynamic on many timescales within the cell, ranging from milliseconds to seconds. In the cytoplasmic regions, far from adhesions, paxillin is uniformly distributed and freely diffusing as a monomer, as determined by single-point fluctuation correlation spectroscopy and photon-counting histogram analysis. Near adhesions, paxillin dynamics are reduced drastically, presumably due to binding to protein partners within the adhesions. The photon-counting histogram analysis of the fluctuation amplitudes reveals that this binding equilibrium in new or assembling adhesions is due to paxillin monomers binding to quasi-immobile structures, whereas in disassembling adhesions or regions of adhesions, the equilibrium is due to exchange of large aggregates. Scanning fluctuation correlation spectroscopy and raster-scan image correlation spectroscopy analysis of laser confocal images show that the environments within adhesions are heterogeneous. Relatively large adhesions appear to slide transversally due to a treadmilling mechanism through the addition of monomeric paxillin at one side and removal of relatively large aggregates of proteins from the retracting edge. Total internal reflection microscopy performed with a fast acquisition EM-CCD camera completes the overall dynamic picture and adds details of the heterogeneous dynamics across single adhesions and simultaneous bursts of activity at many adhesions across the cell

    Use of bioanalyzer electropherograms for quality control and target evaluation in microarray expression profiling studies of ocular tissues

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    Expression profiling with DNA microarrays has been used to examine the transcriptome of a wide spectrum of vertebrate cells and tissues. The sensitivity and accuracy of the data generated is dependent on the quality and composition of the input RNA. In this report, we examine the quality and array performance of over 200 total RNA samples extracted from ocular tissues and cells that have been processed in a microarray core laboratory over a 7-year period. Total RNA integrity and cRNA target size distribution were assessed using the 2100 Bioanalyzer. We present Affymetrix GeneChip array performance metrics for different ocular samples processed according to a standard microarray assay workflow including several quality control checkpoints. Our review of ocular sample performance in the microarray assay demonstrates the value of considering tissue-specific characteristics in evaluating array data. Specifically, we show that Bioanalyzer electropherograms reveal highly abundant mRNAs in lacrimal gland targets that are correlated with variation in array assay performance. Our results provide useful benchmarks for other gene expression studies of ocular systems

    Computational ethics

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    Technological advances are enabling roles for machines that present novel ethical challenges. The study of 'AI ethics' has emerged to confront these challenges, and connects perspectives from philosophy, computer science, law, and economics. Less represented in these interdisciplinary efforts is the perspective of cognitive science. We propose a framework – computational ethics – that specifies how the ethical challenges of AI can be partially addressed by incorporating the study of human moral decision-making. The driver of this framework is a computational version of reflective equilibrium (RE), an approach that seeks coherence between considered judgments and governing principles. The framework has two goals: (i) to inform the engineering of ethical AI systems, and (ii) to characterize human moral judgment and decision-making in computational terms. Working jointly towards these two goals will create the opportunity to integrate diverse research questions, bring together multiple academic communities, uncover new interdisciplinary research topics, and shed light on centuries-old philosophical questions

    Student Learning Outcomes Poster Session for CSB/SJU Joint Board of Trustees Meeting, December 5th, 2014

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    A faculty and student poster session was held focusing on student learning outcomes at the December 5th, 2014 joint Board of Trustee meeting. The posters focused on using assessment of student learning to improve teaching and learning and covered student learning outcomes at the course, departmental, and institutional levels
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