4,079 research outputs found

    Firms' Main Market, Human Capital and Wages

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    Recent international trade literature emphasizes two features in characterizing the current patterns of trade: efficiency heterogeneity at the firm level and quality differentiation. This paper explores human capital and wage differences across firms in that context. We build a partial equilibrium model predicting that firms selling in more-remote markets employ higher human capital and pay higher wages to employees within each education group. The channel linking these variables is firms’ endogenous choice of quality. Predictions are tested using Spanish employer-employee matched data that classify firms according to four main destination markets: local, national, European Union, and rest of the World. Employees’ average education is increasing in the remoteness of firm’s main output market. Market–destination wage premia are large, increasing in the remoteness of the market, and increasing in individual education. These results suggest that increasing globalization may play a significant role in raising wage inequality within and across education groups

    Neural markers of suppression in impaired binocular vision

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    Even after conventional patching treatment, individuals with a history of amblyopia typically lack good stereo vision. This is often attributed to atypical suppression between the eyes, yet the specific mechanism is still unclear. Guided by computational models of binocular vision, we tested explicit predictions about how neural responses to contrast might differ in individuals with impaired binocular vision. Participants with a history of amblyopia (N = 25), and control participants with typical visual development (N = 19) took part in the study. Neural responses to different combinations of contrast in the left and right eyes, were measured using both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Stimuli were sinusoidal gratings with a spatial frequency of 3c/deg, flickering at 4 Hz. In the fMRI experiment, we also ran population receptive field and retinotopic mapping sequences, and a phase-encoded localiser stimulus, to identify voxels in primary visual cortex (V1) sensitive to the main stimulus. Neural responses in both modalities increased monotonically with stimulus contrast. When measured with EEG, responses were attenuated in the weaker eye, consistent with a fixed tonic suppression of that eye. When measured with fMRI, a low contrast stimulus in the weaker eye substantially reduced the response to a high contrast stimulus in the stronger eye. This effect was stronger than when the stimulus-eye pairings were reversed, consistent with unbalanced dynamic suppression between the eyes. Measuring neural responses using different methods leads to different conclusions about visual differences in individuals with impaired binocular vision. Both of the atypical suppression effects may relate to binocular perceptual deficits, e.g. in stereopsis, and we anticipate that these measures could be informative for monitoring the progress of treatments aimed at recovering binocular vision

    On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

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    This is the final version. Available on open access from European Geosciences Union via the DOI in this recordData availability. CarbonTracker CT2016 results were provided by NOAA ESRL, Boulder, Colorado, USA, from the website at https://www.esrl.noaa.gov/gmd/ccgg/carbontracker/ (National Oceanic and Atmospheric Administration (NOAA) Earth System Laboratory (ESRL), 2019a). CASA GFED 4.1 and CASA CMS NEE fluxes were also downloaded from the CT2016 website. The GOSAT L4 product and VISIT NEE were downloaded from the GOSAT Data Archive Service (https://data2.gosat.nies.go.jp; NIES, 2019). The Dai Global Palmer Drought Severity Index was downloaded from the Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory (https://doi.org/10.5065/D6QF8R93; Dai, 2017). NASA GOME-2 SIF products were obtained from the Aura Validation Data Center (https://avdc.gsfc.nasa.gov/; Aura Validation Data Center, 2019). FLUXCOM products were obtained from the data portal of the Max Planck Institute for Biochemistry (https://www.bgc-jena.mpg.de/geodb/projects/Home.php.; Max Plank Institue for Biogeochemistry, 2019). MERRA-2 products were downloaded from MDISC (https://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/; Global Modeling and Assimilation Office, 2019), managed by the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC). The GEOS-Chem forward and adjoint models are freely available to the public. Instructions for downloading and running the models can be found at http://wiki.seas.harvard.edu/geos-chem (Atmospheric Chemistry Modeling Group at Harvard University , 2019). ACOS GOSAT lite files were obtained from the CO2 Virtual Science Data Environment (https://co2.jpl.nasa.gov/; Jet Propulsion Laboratory, California Institute of Technology, 2019). The SST anomalies were downloaded from the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL) website (https://www.esrl.noaa.gov; National Oceanic and Atmospheric Administration (NOAA) Earth System Laboratory (ESRL), 2019b).Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric CO2. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric CO2 observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem adjoint model to assimilate GOSAT observations. Monthly NEE anomalies are compared to "proxies", variables that are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Statistically significant correlations (P<0.05) are obtained between posterior NEE anomalies and anomalies in soil temperature and FLUXCOM NEE on continental and larger scales in the tropics, as well as in the northern extratropics on subcontinental scales during the summer (R2≥0.49), suggesting that GOSAT measurements provide a constraint on NEE interannual variability (IAV) on these spatial scales. Furthermore, we show that GOSAT flux inversions are generally better correlated with the environmental proxies and FLUXCOM NEE than NEE anomalies produced by a set of terrestrial biosphere models (TBMs), suggesting that GOSAT flux inversions could be used to evaluate TBM NEE fluxes.Environment and Climate Change CanadaNatural Sciences and Engineering Research Council of CanadaCanadian Space Agenc

    Inert gas clearance from tissue by co-currently and counter-currently arranged microvessels

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    To elucidate the clearance of dissolved inert gas from tissues, we have developed numerical models of gas transport in a cylindrical block of tissue supplied by one or two capillaries. With two capillaries, attention is given to the effects of co-current and counter-current flow on tissue gas clearance. Clearance by counter-current flow is compared with clearance by a single capillary or by two co-currently arranged capillaries. Effects of the blood velocity, solubility, and diffusivity of the gas in the tissue are investigated using parameters with physiological values. It is found that under the conditions investigated, almost identical clearances are achieved by a single capillary as by a co-current pair when the total flow per tissue volume in each unit is the same (i.e., flow velocity in the single capillary is twice that in each co-current vessel). For both co-current and counter-current arrangements, approximate linear relations exist between the tissue gas clearance rate and tissue blood perfusion rate. However, the counter-current arrangement of capillaries results in less-efficient clearance of the inert gas from tissues. Furthermore, this difference in efficiency increases at higher blood flow rates. At a given blood flow, the simple conduction-capacitance model, which has been used to estimate tissue blood perfusion rate from inert gas clearance, underestimates gas clearance rates predicted by the numerical models for single vessel or for two vessels with co-current flow. This difference is accounted for in discussion, which also considers the choice of parameters and possible effects of microvascular architecture on the interpretation of tissue inert gas clearance

    Surface-Atmosphere Coupling Scale, the Fate of Water, and Ecophysiological Function in a Brazilian Forest

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    This is the final verison. Available from American Geophysical Union (AGU) via the DOI in this record.The K83 observational data are available from AmeriFlux (ameriflux.lbl.gov), NCEP Reanalysis data provided by NOAA/ESRL/PSD, Boulder, Colorado, USA, from the http://www.cdc.noaa.gov/ website. Model code and output is stored at GitLab (gitlab.com). This project is password protected, and the password can be obtained from the corresponding author at [email protected] upon request.Tropical South America plays a central role in global climate. Bowen ratio teleconnects to circulation and precipitation processes far afield, and the global CO2 growth rate is strongly influenced by carbon cycle processes in South America. However, quantification of basin-wide seasonality of flux partitioning between latent and sensible heat, the response to anomalies around climatic norms, and understanding of the processes and mechanisms that control the carbon cycle remains elusive. Here, we investigate simulated surface-atmosphere interaction at a single site in Brazil, using models with different representations of precipitation and cloud processes, as well as differences in scale of coupling between the surface and atmosphere. We find that the model with parameterized clouds/precipitation has a tendency toward unrealistic perpetual light precipitation, while models with explicit treatment of clouds produce more intense and less frequent rain. Models that couple the surface to the atmosphere on the scale of kilometers, as opposed to tens or hundreds of kilometers, produce even more realistic distributions of rainfall. Rainfall intensity has direct consequences for the “fate of water,” or the pathway that a hydrometeor follows once it interacts with the surface. We find that the model with explicit treatment of cloud processes, coupled to the surface at small scales, is the most realistic when compared to observations. These results have implications for simulations of global climate, as the use of models with explicit (as opposed to parameterized) cloud representations becomes more widespread.National Aeronautics and Space Administration (NASA)National Science Foundation (NSF)National Science Foundation (NSF)U.S. Department of Energy (DOE

    Neutrophils from Both Susceptible and Resistant Mice Efficiently Kill Opsonized \u3cem\u3eListeria monocytogenes\u3c/em\u3e

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    Inbred mouse strains differ in their susceptibility to infection with the facultative intracellular bacterium Listeria monocytogenes, largely due to delayed or deficient innate immune responses. Previous antibody depletion studies suggested that neutrophils (polymorphonuclear leukocytes [PMN]) were particularly important for clearance in the liver, but the ability of PMN from susceptible and resistant mice to directly kill L. monocytogenes has not been examined. In this study, we showed that PMN infiltrated the livers of BALB/c/By/J (BALB/c) and C57BL/6 (B6) mice in similar numbers and that both cell types readily migrated toward leukotriene B4 in an in vitro chemotaxis assay. However, CFU burdens in the liver were significantly higher in BALB/c mice than in other strains, suggesting that PMN in the BALB/c liver might not be able to clear L. monocytogenes as efficiently as B6 PMN. Unprimed PMN harvested from either BALB/c or B6 bone marrow killed L. monocytogenes directly ex vivo, and pretreatment with autologous serum significantly enhanced killing efficiency for both. L. monocytogenes were internalized within 10 min and rapidly triggered intracellular production of reactive oxygen species in a dose-dependent manner. However, PMN from gp91phox-deficient mice also readily killed L. monocytogenes, which suggested that nonoxidative killing mechanisms may be sufficient for bacterial clearance. Together, these results indicate that there is not an intrinsic defect in the ability of PMN from susceptible BALB/c mice to kill L. monocytogenes and further suggest that if PMN function is impaired in BALB/c mice, it is likely due to locally produced modulating factors present in the liver during infection

    Cost-Effective Use of Silver Dressings for the Treatment of Hard-to-Heal Chronic Venous Leg Ulcers

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    Aim To estimate the cost-effectiveness of silver dressings using a health economic model based on time-to-wound-healing in hard-to-heal chronic venous leg ulcers (VLUs). Background Chronic venous ulceration affects 1–3% of the adult population and typically has a protracted course of healing, resulting in considerable costs to the healthcare system. The pathogenesis of VLUs includes excessive and prolonged inflammation which is often related to critical colonisation and early infection. The use of silver dressings to control this bioburden and improve wound healing rates remains controversial. Methods A decision tree was constructed to evaluate the cost-effectiveness of treatment with silver compared with non-silver dressings for four weeks in a primary care setting. The outcomes: ‘Healed ulcer’, ‘Healing ulcer’ or ‘No improvement’ were developed, reflecting the relative reduction in ulcer area from baseline to four weeks of treatment. A data set from a recent meta-analysis, based on four RCTs, was applied to the model. Results Treatment with silver dressings for an initial four weeks was found to give a total cost saving (£141.57) compared with treatment with non-silver dressings. In addition, patients treated with silver dressings had a faster wound closure compared with those who had been treated with non-silver dressings. Conclusion The use of silver dressings improves healing time and can lead to overall cost savings. These results can be used to guide healthcare decision makers in evaluating the economic aspects of treatment with silver dressings in hard-to-heal chronic VLUs

    Management of Acute COPD Exacerbations in Australia: Do we Follow the Guidelines?

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    Objective: We aimed to assess adherence to the Australian national guideline (COPD-X) against audited practice, and to document the outcomes of patients hospitalised with an acute exacerbation of chronic obstructive pulmonary disease (COPD) at discharge and 28 days after. Methods: A prospective clinical audit of COPD hospital admission from five tertiary care hospitals in five states of Australia was conducted. Post-discharge follow-up was conducted via telephone to assess for readmission and health status. Results: There were 207 admissions for acute exacerbation (171 patients; mean 70.2 years old; 50.3%males). Readmission rates at 28 days were 25.4%, with one (0.6%) death during admission and eight(6.1%) post-discharge within 28 days. Concordance to the COPD-X guidance was variable; 22.7% performed spirometry, 81.1% had blood gases collected when forced expiratory volume in 1 s was \u3c1 \u3eL,99.5% had chest radiography performed, 95.1% were prescribed systemic corticosteroids and 95% were prescribed antibiotic therapy. There were 89.1% given oxygen therapy and 92.6% when arterial oxygen tension was \u3c80 \u3emmHg; 65.6% were given ventilatory assistance when pH was Conclusion: When compared against clinical practice guidelines, we found important gaps in management of patients admitted with COPD throughout tertiary care centres in Australia. Strategies to improve guideline uptake are needed to optimise care
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