344 research outputs found

    Optically and x-ray selected galaxy groups at intermediate redshift

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    In this thesis I present the properties of two samples of galaxy groups containing 39 high quality X-ray selected systems and 38 optically (spectroscopically) selected systems in coincident spatial regions at 0.12<z<0.79. Only nine optical systems are associable with X-ray systems. I discuss the confusion inherent in the matching of both galaxies to extended X-ray emission and of X-ray emission to already identified optical systems. Extensive spectroscopy has been obtained and the resultant redshift catalog and group membership are provided here. X-ray, dynamical, and total stellar masses (integrated down to a limit of 10^10 M⊙) of the groups are also derived and presented. The total mass range of the combined sample is ∼10^12 − 5 × 10 ^14 M⊙. I explore the effects of utilizing different centers and applying three different kinds of radial cut to the systems: a constant cut of 1 Mpc and two r200 cuts (roughly approximating a virial radius), one based on the velocity dispersion of the system and the other on the X-ray emission. I find that an X-ray based r200 tends to result in less scatter in scaling relations and less dynamical complexity of member galaxies as evidenced by results of the Anderson-Darling and Dressler-Shectman tests, indicating that this radius tends to isolate the virialized part of the system. The constant and velocity dispersion based cuts can overestimate membership and can work to inflate velocity dispersion and dynamical and stellar mass. I fit Lx-σ and Mstellar-Lx scaling relations for X-ray and optically selected systems and find they are not dissimilar. The mean fraction of mass found in stars for my systems is ∼0.014 with a logarithmic standard deviation of 0.398 dex. I also define and investigate a sample of groups which are X-ray underluminous given the total group stellar mass. For these systems the fraction of stellar mass contributed by the most massive galaxy is typically lower than that found for the total population of groups. 80% of 15 underluminous groups have less than 40% of their stellar mass in the most massive galaxy which only happens in less than 1% of cases with samples matched in stellar mass, taken from the combined group catalog. These results imply that there may be less Intra-Group Medium contributed from the most massive member in these systems, supporting the model of hierarchical collapse wherein a group begins with a massive galaxy and accretes mass smoothly, resulting in a group with a higher gas fraction and a more massive central galaxy than would result from the merger of roughly equivalent mass ‘subgroups’ (clumps) comprised of similar mass / luminosity galaxies

    Is Habitat Use by Greater Sage-Grouse Proportional to Availability of Plant Morphotypes?

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    Greater Sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) select sagebrush plants for food that are high in protein. However, sagebrush produce toxins called monoterpenes that can inhibit enzymatic reactions and interrupt cellular processes and therefore result in decreased intake by sage-grouse. Moreover, species, subspecies, populations, and morphotypes of sagebrush can vary in the concentration of toxins produced. Preliminary analysis has shown that different morphotypes of sagebrush have different chemical profiles, and this may influence selection at a scale below species. Our research aims to determine whether sage-grouse select specific morphotypes of sagebrush to maximize biomass consumed per bite or minimize toxin consumed per bite and, how that selection changes with plant density or abundance. We flushed radio-marked sage-grouse and identified their foraging site using tracks and fresh pellets. At each used patch, we performed density counts for each morphotype of sagebrush along atransect, and recorded the volume and number of bite marks for each plant. We will evaluate if sage-grouse browse certain morphotypes in proportion to their availability, or if they differentially select morphotypes to browse based on biomass per bite or toxin concentration per bite. This research contributes to a growing understanding of how sage-grouse select and use habitats throughout the year, which is increasingly important as habitat availability decreases, the distribution of specific morphotypes change and remaining landscapes are degraded. Additionally, this research provides insight about plant-herbivore interactions and how herbivores select plants to consume, based on biomass intake rates, toxin concentration, or availability of plants

    Using Age as a Predictor of Chemotypes for Low Sagebrush (\u3cem\u3eArtemisia Arbuscula\u3c/em\u3e): Can Age Help Us Manage Sage-Grouse Foraging Habitat?

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    The defensive chemistry of plants limit intake by herbivores. In addition, the spatial and temporal variation of plant chemicals constrains habitat use by herbivores. As such, management of herbivores requires that we properly conserve and manage for the most palatable chemical profiles of plants, or chemotypes. However, management of palatable plants requires that we first identify parameters that influence chemotypes. We hypothesized that the age of a plant is one parameter that influences chemotypes and could be managed. To test this hypothesis, we counted the annual ring growth to determine age and used gas chromatography to determine chemotypes of small (tall) and medium (15cm-30cm tall) low sagebrush (Artemisia arbuscula). We focused on low sagebrush as it is a preferred food source for greater sage-grouse (Centrocercus urophasianus) at our study site. In addition, we tested whether the circumference at the base of the plant is correlated with annual ring growth. Correlating age and circumference may yield a simple, nonintrusive method to estimate the age of sagebrush in the field without counting annual rings. Understanding how age influences palatability of plants is an important factor in assessing and managing grouse habitat. Using a parameter like age, which may be simple to assess in field, to manage sage-steppe habitats could save time and money. We expect if the younger plants are more palatable, reseeding and replanting could be effective methods to make restored habitats more ideal for foraging grouse. Alternatively, if older plants are more palatable the consequences of mowing and herbicide could dramatically outweigh any potential benefits

    Assessing the Psychoeducational Approach to Transcendence and Health (PATH) program : an intervention to foster self-transcendence and well-being in community-dwelling older adults.

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    The late-life developmental process of self-transcendence shapes elders’ perspectives on self, others, the nature of this world, and of a dimension beyond the here and now. This qualitative pilot study evaluated the Psychoeducational Approach to Transcendence and Health (PATH) Program, a psychoeducational intervention to promote self-transcendence and well-being in community-dwelling women at a senior center. The intervention involved eight weekly group sessions using group processes, mindfulness practices, creative experiences, and independent at-home practice. The findings supported the underlying theory-based structure and content of the intervention and indicated the intervention may empower elders to attend to self-care, develop acceptance, and learn new skills associated with health and well-being, thus merits further study. Based on insights gained from facilitators’ and participants’ experiences and perceptions, the intervention will be revised and strengthened

    Shoulder electromyography activity during push-up variations: a scoping review

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    Background: Push-ups (PU) are a common closed chain exercise used to enhance shoulder girdle stability, with variations that alter the difficulty or target specific muscles. To appropriately select and prescribe PU exercises, an understanding of muscle activity during variations of the PU is needed. The purpose of this scoping review was to identify common PU variations and describe their muscle activation levels. Methods: Databases searched included PubMed, CINAHL, Scopus, and SPORTDiscus for articles published between January 2000 and November 2019. Results: Three hundred three articles were screened for eligibility with 30 articles included in the analysis. Six PU types and five muscles met the criteria for analysis. Weighted mean electromyography (EMG) amplitude was calculated for each muscle across PU types and for each PU type as a measure of global muscle activity. Triceps and pectoralis major had the highest EMG amplitude during unstable, suspension, incline with hands on a ball and the standard PU. Serratus anterior had the highest EMG amplitude during PU plus and incline PU. The greatest global EMG amplitude occurred during unstable surface PU. Discussion: These results provide clinicians with a framework for prescribing PU to target specific muscles and scale exercise difficulty to facilitate rehabilitation outcomes

    Phytochemistry Predicts Habitat Selection by an Avian Herbivore at Multiple Spatial Scales

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    Animal habitat selection is a process that functions at multiple, hierarchically structured spatial scales. Thus multi-scale analyses should be the basis for inferences about factors driving the habitat selection process. Vertebrate herbivores forage selectively on the basis of phytochemistry, but few studies have investigated the influence of selective foraging (i.e., fine-scale habitat selection) on habitat selection at larger scales. We tested the hypothesis that phytochemistry is integral to the habitat selection process for vertebrate herbivores. We predicted that habitats selected at three spatial scales would be characterized by higher nutrient concentrations and lower concentrations of plant secondary metabolites (PSMs) than unused habitats. We used the Greater Sage-Grouse (Centrocercus urophasianus), an avian herbivore with a seasonally specialized diet of sagebrush, to test our hypothesis. Sage-Grouse selected a habitat type (black sagebrush, Artemisia nova) with lower PSM concentrations than the alternative (Wyoming big sagebrush, A. tridentata wyomingensis). Within black sagebrush habitat, Sage-Grouse selected patches and individual plants within those patches that were higher in nutrient concentrations and lower in PSM concentrations than those not used. Our results provide the first evidence for multi-scale habitat selection by an avian herbivore on the basis of phytochemistry, and they suggest that phytochemistry may be a fundamental driver of habitat selection for vertebrate herbivores

    Promoting self-transcendence and well-being in community-dwelling older adults : a pilot study of a psychoeducational intervention.

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    Self-transcendence changes how older adults perceive themselves, their relationships with others, the material world, and the metaphysical or spiritual dimension. It is associated with multiple indicators of well-being. The purpose of this pilot study (N = 20) was to examine the feasibility and effectiveness of a psychoeducational intervention to increase self-transcendence and well-being of older adults. Data were analyzed using generalized estimating equations. All variables trended in the directions hypothesized. Self-transcendence increased in the intervention group and decreased in the control group but not significantly. The group × time interaction for life satisfaction was significant (z = 2.89, p = .004). This feasibility study supports further investigation to assess the effectiveness of the intervention in a larger sample

    Developments in marine pCO2 measurement technology; towards sustained in situ observations

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    The oceanic uptake of anthropogenic CO2 causes pronounced changes to the marine carbonate system. High quality pCO2 measurements with good temporal and spatial coverage are required to monitor the oceanic uptake, identify regions with pronounced carbonate system changes, and observe the effectiveness of CO2 emission mitigation strategies. There are currently several instruments available, but many are unsuitable for autonomous deployments on in situ platforms such as gliders, moorings and Argo floats. We assess currently available technology on its suitability for in situ deployment, with a focus on optode technology developments. Optodes for pCO2 measurements provide a promising new technological approach, and were successfully calibrated over the range of 280–480 μatm applying modified time-domain dual lifetime referencing. A laboratory precision of 0.8 μatm (n = 10) and a response time (τ90) of 165 s were achieved, and with further development pCO2 optodes may become as widely used as their oxygen counterparts

    Clusters of Adaptive Evolution in the Human Genome

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    Considerable work has been devoted to identifying regions of the human genome that have been subjected to recent positive selection. Although detailed follow-up studies of putatively selected regions are critical for a deeper understanding of human evolutionary history, such studies have received comparably less attention. Recently, we have shown that ALMS1 has been the target of recent positive selection acting on standing variation in Eurasian populations. Here, we describe a careful follow-up analysis of genetic variation across the ALMS1 region, which unexpectedly revealed a cluster of substrates of positive selection. Specifically, through the analysis of SNP data from the HapMap and Human Genome Diversity Project–Centre d’Etude du Polymorphisme Humain samples as well sequence data from the region, we find compelling evidence for three independent and distinct signals of recent positive selection across this 3 Mb region surrounding ALMS1. Moreover, we analyzed the HapMap data to identify other putative clusters of independent selective events and conservatively discovered 19 additional clusters of adaptive evolution. This work has important implications for the interpretation of genome-scans for positive selection in humans and more broadly contributes to a better understanding of how recent positive selection has shaped genetic variation across the human genome
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