3,334 research outputs found

    Microsurgical Reconstruction of Large, Locally Advanced Cutaneous Malignancy of the Head and Neck

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    Large, locally advanced cutaneous malignancy of the head and neck region is rare. However, when present, they impart a significant reconstructive challenge. These cancers have a tendency to invade peripheral tissues covering a large surface area as well as expose deeper structures such as skull, dura, orbit, and sinus after resection. Complicating the reconstructive dilemma is the high incidence of individuals who have undergone previous surgery in the region as well as adjuvant radiation therapy, which may preclude the use of local flaps or skin graft. Free tissue transfer provides a reconstructive surgeon the ability to provide well-vascularized tissue with adequate volume not limited by arc of rotation

    A Review of Primary Cardiomyopathy in the Cat

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    Primary cardiomyopathy in cats has been recognized in the literature as a clinical entity only since 1970. Prior to this, the recognition of this disease had been in association with aortic thromboembolism, an important complication of cardiomyopathy, because the etiologies of the several forms of cardiomyopathy are unknown classification has been based on nature of the hemodynamic fault or the anatomical abnormality that is present. The two most basic and common forms are hypertrophic cardiomyopathy and congestive cardiomyopathy

    Congestive Cardiomyopathy in the Canine

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    Diseases of the myocardium can be classified either as primary or secondary. Primary cardiomyopathies include idiopathic congestive or hypertropic forms. Causes of secondary cardiomyopathies are primary, systemic diseases, the most common of which are infectious, metabolic, toxic, ischemic, and neoplastic diseases that cause some myocardial damage

    Characterization of site-specific GPS errors using a short-baseline network of braced monuments at Yucca Mountain, southern Nevada

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    We use a short-baseline network of braced monuments to investigate site-specific GPS effects. The network has baseline lengths of ∼10, 100, and 1000 m. Baseline time series have root mean square (RMS) residuals, about a model for the seasonal cycle, of 0.05–0.24 mm for the horizontal components and 0.20–0.72 mm for the radial. Seasonal cycles occur, with amplitudes of 0.04–0.60 mm, even for the horizontal components and even for the shortest baselines. For many time series these lag seasonal cycles in local temperature measurements by 23–43 days. This could suggest that they are related to bedrock thermal expansion. Both shorter-period signals and seasonal cycles for shorter baselines to REP2, the one short-braced monument in our network, are correlated with temperature, with no lag time. Differences between REP2 and the other stations, which are deep-braced, should reflect processes occurring in the upper few meters of the ground. These correlations may be related to thermal expansion of these upper ground layers, and/or thermal expansion of the monuments themselves. Even over these short distances we see a systematic increase in RMS values with increasing baseline length. This, and the low RMS levels, suggests that site-specific effects are unlikely to be the limiting factor in the use of similar GPS sites for geophysical investigations

    Ionic conductivity on a wetting surface

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    Recent experiments measuring the electrical conductivity of DNA molecules highlight the need for a theoretical model of ion transport along a charged surface. Here we present a simple theory based on the idea of unbinding of ion pairs. The strong humidity dependence of conductivity is explained by the decrease in the electrostatic self-energy of a separated pair when a layer of water (with high dielectric constant) is adsorbed to the surface. We compare our prediction for conductivity to experiment, and discuss the limits of its applicability.Comment: 5 pages, 3 figures; one section and two illustrations added; figures updated and discussion added; typo fixe

    Sex Differences in Change in Skin Temperature When Exercising in a Hot, Humid Environment

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    The risk for heat-related illness is increased when exercising in a hot, humid environment. In an effort to protect the athlete, body temperature is measured continuously while exercising in extreme environments. Currently, researchers and laboratory personnel employ the use of mean skin temperature to monitor athlete safety; however, this measurement fails to consider localized changes in temperature that may arise as a function of sex and exercise time. Therefore, the purpose of this study was to examine potential sex differences in the change in skin temperature at 17 different upper body locations while exercising in a hot, humid environment. Young men and women were recruited and completed a 60-min walk/jog interval protocol in a hot (34.1 ± 1 °C), humid (64 ± 8%) environment while skin temperature was continuously measured. To account for differences that may have arisen due to differing workloads between men and women, energy expenditure and metabolic heat production were calculated after the completion of exercise. Data was analyzed either a repeated-measures ANOVA (change in skin temperature) or t-test­ (energy expenditure and metabolic heat production). Location of interaction effects was determined using a Fisher’s Least Significant Difference test. Significance was set a p\u3c0.05 for all statistical testing. There was no difference between men and women in total energy expenditure; however, men were found to have a higher metabolic heat production. Women had a higher change in skin temperature at three locations on the back (left upper, right upper, and right mid-back). Conversely, there were no differences at any time point between men and women in the change in core temperature from baseline measurements. This study highlights the need to further investigate sex differences in cooling mechanisms while exercising in a hot, humid environment

    Near-Infrared Spectroscopy of Carbon-Enhanced Metal-Poor Stars. I. A SOAR/OSIRIS Pilot Study

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    We report on an abundance analysis for a pilot study of seven Carbon-Enhanced Metal-Poor (CEMP) stars, based on medium-resolution optical and near-infrared spectroscopy. The optical spectra are used to estimate [Fe/H], [C/Fe], [N/Fe], and [Ba/Fe] for our program stars. The near-infrared spectra, obtained during a limited early science run with the new SOAR 4.1m telescope and the Ohio State Infrared Imager and Spectrograph (OSIRIS), are used to obtain estimates of [O/Fe] and 12C/13C. The chemical abundances of CEMP stars are of importance for understanding the origin of CNO in the early Galaxy, as well as for placing constraints on the operation of the astrophysical s-process in very low-metallicity Asymptotic Giant Branch (AGB) stars. This pilot study includes a few stars with previously measured [Fe/H], [C/Fe], [N/Fe],[O/Fe], 12C/13C, and [Ba/Fe], based on high-resolution optical spectra obtained with large-aperture telescopes. Our analysis demonstrates that we are able to achieve reasonably accurate determinations of these quantities for CEMP stars from moderate-resolution optical and near-infrared spectra. This opens the pathway for the study of significantly larger samples of CEMP stars in the near future. Furthermore, the ability to measure [Ba/Fe] for (at least the cooler) CEMP stars should enable one to separate stars that are likely to be associated with s-process enhancements (the CEMP-s stars) from those that do not exhibit neutron-capture enhancements (the CEMP-no stars).Comment: 27 pages, including 5 tables, 6 figures, accepted for publication in The Astronomical Journa

    Evidence Suggesting that Ivory-billed Woodpeckers (Campephilus principalis) Exist in Florida

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    The Ivory-billed Woodpecker (Campephilus principalis) disappeared from the forests of southeastern North America in the early 20th Century and for more than 50 years has been widely considered extinct. On 21 May 2005, we detected a bird that we identified as an Ivory-billed Woodpecker in the mature swamp forest along the Choctawhatchee River in the panhandle of Florida. During a subsequent year of research, members of our small search team observed birds that we identified as Ivory-billed Woodpeckers on 14 occasions. We heard sounds that matched descriptions of Ivory-billed Woodpecker acoustic signals on 41 occasions. We recorded 99 putative double knocks and 210 putative kent calls. We located cavities in the size range reported for Ivory-billed Woodpeckers and larger than those of Pileated Woodpeckers (Dryocopus pileatus) that have been reported in the literature or that we measured in Alabama. We documented unique foraging signs consistent with the feeding behavior of Ivory-billed Woodpeckers. Our evidence suggests that Ivory-billed Woodpeckers may be present in the forests along the Choctawhatchee River and warrants an expanded search of this bottomland forest habitat

    The Influence of Particle Concentration and Bulk Characteristics on Polarized Oceanographic Lidar Measurements

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    Oceanographic lidar measurements of the linear depolarization ratio, δ, contain information on the bulk characteristics of marine particles that could improve our ability to study ocean biogeochemistry. However, a scarcity of information on the polarized light-scattering properties of marine particles and the lack of a framework for separating single and multiple scattering effects on δ have hindered the development of polarization-based retrievals of bulk particle properties. To address these knowledge gaps, we made single scattering measurements of δ for several compositionally and morphologically distinct marine particle assemblages. We then used a bio-optical model to explore the influence of multiple scattering and particle characteristics on lidar measurements of δ made during an expedition to sample a mesoscale coccolithophore bloom. Laboratory measurements of linear depolarization revealed a complex dependency on particle shape, size, and composition that were consistent with scattering simulations for idealized nonspherical particles. Model results suggested that the variability in δ measured during the field expedition was driven predominantly by shifts in particle concentration rather than their bulk characteristics. However, model estimates of δ improved when calcite particles were represented by a distinct particle class, highlighting the influence of bulk particle properties on δ. To advance polarized lidar retrievals of bulk particle properties and to constrain the uncertainty in satellite lidar retrievals of particulate backscattering, these results point to the need for future efforts to characterize the variability of particulate depolarization in the ocean and to quantify the sensitivity of operational ocean lidar systems to multiple scattering
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