1,137 research outputs found

    Studies on the flight medical aspects of the German Lufthansa non-stop route from Frankfurt to Rio de Janeiro, part 1

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    The problem of crew size for regularly scheduled flights between Frankfurt and Rio de Janeiro is discussed. Factors affecting crew performance are examined, comparisons are drawn to regulations of other countries and crew questionnaires and tests are presented

    The sequelae of a missed Essex-Lopresti lesion

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    Radial head fractures are the most common type of elbow fracture in adults. Unrecognised disruption of the intraosseous membrane at the time of injury can lead to severe wrist pain from proximal radial migration especially if the radial head is excised. In this case, despite anatomical reduction and internal fixation of the radial head fracture, longitudinal forearm instability developed after delayed radial head resection was performed 7 months post-injury. A Suave-Kapandji procedure was performed due to ongoing wrist pain. Because of the previous radial head resection, this led to a floating forearm that could only be solved by creating a one-bone forearm, sacrificing all forearm rotation to achieve a stable lever arm between the elbow and wrist joint

    Building capacity in remote sensing for conservation: present and future challenges

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    Remote sensing (RS) has made significant contributions to conservation and ecology; however, direct use of RS-based information for conservation decision making is currently very limited. In this paper, we discuss the reasons and challenges associated with using RS technology by conservationists and suggest how training in RS for conservationists can be improved. We present the results from a survey organized by the Conservation Remote Sensing Network to understand the RS expertise and training needs of various categories of professionals involved in conservation research and implementation. The results of the survey highlight the main gaps and priorities in the current RS data and technology among conservation practitioners from academia, institutions, NGOs and industry. We suggest training to be focused around conservation questions that can be addressed using RS-derived information rather than training pure RS methods which are beyond the interest of conservation practitioners. We highlight the importance of developing essential biodiversity variables (EBVs) and how this can be achieved by increasing the RS capacity of the conservation community. Moreover, we suggest that open-source software is adopted more widely in the training modules to facilitate access to RS data and products in developing countries, and that online platforms providing mapping tools should also be more widely distributed. We believe that improved RS capacity among conservation scientists will be essential to improve conservation efforts on the ground and will make the conservation community a key player in the definition of future RS-based products that serve conservation and ecological needs

    Rebirth of X-ray Emission from the Born-Again Planetary Nebula A 30

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    The planetary nebula (PN) A30 is believed to have undergone a very late thermal pulse resulting in the ejection of knots of hydrogen-poor material. Using HST images we have detected the angular expansion of these knots and derived an age of 850+280-150 yr. To investigate the spectral and spatial properties of the soft X-ray emission detected by ROSAT, we have obtained Chandra and XMM-Newton observations of A30. The X-ray emission from A30 can be separated into two components: a point-source at the central star and diffuse emission associated with the hydrogen-poor knots and the cloverleaf structure inside the nebular shell. To help us assess the role of the current stellar wind in powering this X-ray emission, we have determined the stellar parameters of the central star of A 30 using a non-LTE model fit to its optical and UV spectrum. The spatial distribution and spectral properties of the diffuse X-ray emission is suggestive that it is generated by the post-born-again and present fast stellar winds interacting with the hydrogen-poor ejecta of the born-again event. This emission can be attributed to shock-heated plasma, as the hydrogen-poor knots are ablated by the stellar winds, under which circumstances the efficient mass-loading of the present fast stellar wind raises its density and damps its velocity to produce the observed diffuse soft X-rays. Charge transfer reactions between the ions of the stellar winds and material of the born-again ejecta has also been considered as a possible mechanism for the production of diffuse X-ray emission, and upper limits on the expected X-ray production by this mechanism have been derived. The origin of the X-ray emission from the central star of A 30 is puzzling: shocks in the present fast stellar wind and photospheric emission can be ruled out, while the development of a new, compact hot bubble confining the fast stellar wind seems implausible.Comment: 29 pages, 11 figures, 4 tables; accepted for publication by Ap

    Spectral Analysis of the Chandra Comet Survey

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    We present results of the analysis of cometary X-ray spectra with an extended version of our charge exchange emission model (Bodewits et al. 2006). We have applied this model to the sample of 8 comets thus far observed with the Chandra X-ray observatory and ACIS spectrometer in the 300-1000 eV range. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), C/2000 WM1 (LINEAR), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), C/2001 Q4 (NEAT), 9P/2005 (Tempel 1) and 73P/2006-B (Schwassmann-Wachmann 3) and the observations include a broad variety of comets, solar wind environments and observational conditions. The interaction model is based on state selective, velocity dependent charge exchange cross sections and is used to explore how cometary X-ray emission depend on cometary, observational and solar wind characteristics. It is further demonstrated that cometary X-ray spectra mainly reflect the state of the local solar wind. The current sample of Chandra observations was fit using the constrains of the charge exchange model, and relative solar wind abundances were derived from the X-ray spectra. Our analysis showed that spectral differences can be ascribed to different solar wind states, as such identifying comets interacting with (I) fast, cold wind, (II), slow, warm wind and (III) disturbed, fast, hot winds associated with interplanetary coronal mass ejections. We furthermore predict the existence of a fourth spectral class, associated with the cool, fast high latitude wind.Comment: 16 pages, 16 figures, and 7 Tables; accepted A&A (Due to space limits, this version has lower resolution jpeg images.

    Fifty-kDa Hyaluronic Acid Upregulates Some Epidermal Genes without Changing TNF-α Expression in Reconstituted Epidermis

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    Background: Due to its strong water binding potential, hyaluronic acid (HA) is a well-known active ingredient for cosmetic applications. However, based on its varying molecular size, skin penetration of HA may be limited. Recent studies have demonstrated that low-molecular-weight HA (LMW HA) may show a certain proinflammatory activity. We thus aimed to characterize an LMW-sized HA molecule that combines strong anti-aging abilities with efficient skin penetration but lacks potential proinflammatory effects. Methods: Total RNA and total protein were isolated from reconstituted human epidermis following incubation with HAs of various molecular weights (20, 50, 130, 300, 800 and 1,500 kDa). Tumor necrosis factor-alpha expression was determined using quantitative PCR. Genonnic and proteomic expression of various junctional proteins was determined using Affymetrix and common Western blotting techniques. Results: LMW HA of approximately 50 kDa did not significantly alter tumor necrosis factor-alpha expression compared to 20-kDa HA, but revealed significantly higher skin penetration rates than larger sized HA associated with increased expression of genes and proteins known to be involved in tight junction formation and keratinocyte cohesion. Conclusion: LMW HA of approximately 50 kDa shows better penetration abilities than larger-sized HA. In addition, LMW HA influences the expression of various genes including those contributing to keratinocyte differentiation and formation of intercellular tight junction complexes without showing proinflammatory activity. These observations contribute to current knowledge on the effects of LMW HA on keratinocyte biology and cutaneous physiology. Copyright (C) 2011 S. Karger AG, Base

    A Confirmatory Factor Analysis of Home Environment and Home Social Behavior Data from the Elementary School Success Profile for Families

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    The purpose of the current study was to test the factor structure and scale quality of data provided by caregivers about the home environment and child behavior at home using the Elementary School Success Profile (ESSP) for Families. The ESSP for Families is one component of the ESSP, an online social–environmental assessment that also collects information from students and teachers. Confirmatory factor analyses with Mplus and weighted least squares means and variances adjusted estimation took into account the hierarchical nature and ordinal level of the data. The sample comprised caregivers of 692 third- through fifth-grade students from 13 elementary schools in four districts. A primary model and an alternative model were tested. Models were tested on a random calibration sample and validated with another sample. A nine-factor first-order solution demonstrated superior fit to the data. Scores from the nine scales also demonstrated acceptable internal consistency reliability. Implications for practice and further research are presented

    Many-body approach to proton emission and the role of spectroscopic factors

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    The process of proton emission from nuclei is studied by utilizing the two-potential approach of Gurvitz and Kalbermann in the context of the full many-body problem. A time-dependent approach is used for calculating the decay width. Starting from an initial many-body quasi-stationary state, we employ the Feshbach projection operator approach and reduce the formalism to an effective one-body problem. We show that the decay width can be expressed in terms of a one-body matrix element multiplied by a normalization factor. We demonstrate that the traditional interpretation of this normalization as the square root of a spectroscopic factor is only valid for one particular choice of projection operator. This causes no problem for the calculation of the decay width in a consistent microscopic approach, but it leads to ambiguities in the interpretation of experimental results. In particular, spectroscopic factors extracted from a comparison of the measured decay width with a calculated single-particle width may be affected.Comment: 17 pages, Revte

    Paleo-denudation rates suggest variations in runoff drove aggradation during last glacial cycle, Crete, Greece

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    Fluvial aggradation and incision are often linked to Quaternary climate cycles, but it usually remains unclear whether variations in runoff or sediment supply or both drive channel response to climate variability. Here we quantify sediment supply with paleo-denudation rates and provide geochronological constraints on aggradation and incision from the Sfakia and Elafonisi alluvial-fan sequences in Crete, Greece. We report seven optically stimulated luminescence and ten radiocarbon ages, eight 10Be and eight 36Cl denudation rates from modern channel and terrace sediments. For five samples, 10Be and 36Cl were measured on the same sample by measuring 10Be on chert and 36Cl on calcite. Results indicate relatively steady denudation rates throughout the past 80 kyr, but the aggradation and incision history indicates a link with climate shifts. At the Elafonisi fan, we identify four periods of aggradation coinciding with Marine Isotope Stages (MIS) 2, 4, 5a/b, and likely 6, and three periods of incision coinciding with MIS 1, 3, and likely 5e. At the Sfakia fan, rapid aggradation occurred during MIS 2 and 4, followed by incision during MIS 1. Nearby climate and vegetation records show that MIS 2, 4, and 6 stadials were characterized by cold and dry climates with sparse vegetation, whereas forest cover and more humid conditions prevailed during MIS 1, 3, and 5. Our data thus suggest that past changes in climate had little effect on landscape-wide denudation rates but exerted a strong control on the aggradation–incision behaviour of alluvial channels on Crete. During glacial stages, we attribute aggradation to hillslope sediment release promoted by reduced vegetation cover and decreased runoff; conversely, incision occurred during relatively warm and wet stages due to increased runoff. In this landscape, past hydroclimate variations outcompeted changes in sediment supply as the primary driver of alluvial deposition and incision
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