1,174 research outputs found

    W. Arthur Lewis in Retrospect

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    This paper reviews several themes from the writings of W. Arthur Lewis, both the first black Nobel Laureate in Economics and the first from a developing country, and examines them from the perspective of two to five decades of hindsight. The paper emphasizes three main interrelated aspects; economic growth, economic dualism, and the evolution of the economic order -the forces that drive the prices of goods and relative incomes across countries. Lewis\u27s messages still resonate today, as he foresaw the rise of industrial exports from developing countries-and also that it would not end the large gaps among nations\u27 standards of living. The paper both documents these rises and asks whether one could have predicted it from information available in the 1960s, or whether additional prescience was necessary

    Beet necrotic yellow vein virus accumulates inside resting spores and zoosporangia of its vector Polymyxa betae BNYVV infects P. betae

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    BACKGROUND: Plasmodiophorids and chytrids are zoosporic parasites of algae and land plant and are distributed worldwide. There are 35 species belonging to the order Plasmodiophorales and three species, Polymyxa betae, P. graminis, and Spongospora subterranea, are plant viral vectors. Plasmodiophorid transmitted viruses are positive strand RNA viruses belonging to five genera. Beet necrotic yellow vein virus (BNYVV) and its vector, P. betae, are the causal agents for rhizomania. RESULTS: Evidence of BNYVV replication and movement proteins associating with P. betae resting spores was initially obtained using immunofluorescence labeling and well characterized antisera to each of the BNYVV proteins. Root cross sections were further examined using immunogold labeling and electron microscopy. BNYVV proteins translated from each of the four genomic and subgenomic RNAs accumulate inside P. betae resting spores and zoospores. Statistical analysis was used to determine if immunolabelling detected viral proteins in specific subcellular domains and at a level greater than in control samples. CONCLUSION: Virus-like particles were detected in zoosporangia. Association of BNYVV replication and movement proteins with sporangial and sporogenic stages of P. betae suggest that BNYVV resides inside its vector during more than one life cycle stage. These data suggest that P. betae might be a host as well as a vector for BNYV

    Demographic Predictors of the Perceived Likelihood of Hiring a Health Care Advocate

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    Background and Significance: The field of health care advocacy developed in response to the growing complexity of the health care system. A Health Care Advocate (HCA) is a trained professional who can help patients navigate the health care system. In the present study we investigated the effects of social support, number of people with whom individuals reside, gender, age, income, and race on the perceived likelihood of hiring an HCA for oneself. Method: Nine hundred and eighty-seven adults (Mage = 45.48 years, SD = 17.33 years, 55.4% female) were randomly selected and asked to complete a questionnaire. To explore the relationships of the perceived likelihood of hiring an HCA, path-analytic models using full-information maximum likelihood (FIML) estimation were tested, using Stata 12.1. Results: The model fit well statistically, ? 2 (5, N = 987) = 8.50, p = 0.131, and descriptively, CFI = 0.999, RMSEA = 0.027, pclose = 0.891, CD = 0.205. Conclusion: Overall, the model accounted for 4.30% of the variance in Hire HCA. More research is needed to better understand the role of an HCA in our complex and everchanging health care system

    Multisensor navigation systems: a remedy for GNSS vulnerabilities?

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    Space-based positioning, navigation, and timing (PNT) technologies, such as the global navigation satellite systems (GNSS) provide position, velocity, and timing information to an unlimited number of users around the world. In recent years, PNT information has become increasingly critical to the security, safety, and prosperity of the World's population, and is now widely recognized as an essential element of the global information infrastructure. Due to its vulnerabilities and line-of-sight requirements, GNSS alone is unable to provide PNT with the required levels of integrity, accuracy, continuity, and reliability. A multisensor navigation approach offers an effective augmentation in GNSS-challenged environments that holds a promise of delivering robust and resilient PNT. Traditionally, sensors such as inertial measurement units (IMUs), barometers, magnetometers, odometers, and digital compasses, have been used. However, recent trends have largely focused on image-based, terrain-based and collaborative navigation to recover the user location. This paper offers a review of the technological advances that have taken place in PNT over the last two decades, and discusses various hybridizations of multisensory systems, building upon the fundamental GNSS/IMU integration. The most important conclusion of this study is that in order to meet the challenging goals of delivering continuous, accurate and robust PNT to the ever-growing numbers of users, the hybridization of a suite of different PNT solutions is required

    Elements of attention in HIV-infected adults: Evaluation of an existing model

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    Because of the multifactorial nature of neuropsychological tests, attention remains poorly defined from a neuropsychological perspective, and conclusions made regarding attention across studies may be limited due to the different nature of the measures used. Thus, a more definitive schema for this neurocognitive domain is needed. We assessed the applicability of Mirsky and Duncan\u27s (2001) neuropsychological model of attention to a cohort of 104 HIV+ adults. Our analysis resulted in a five-factor structure similar to that of previous studies, which explained 74.5% of the variance. However, based on the psychometric characteristics of the measures comprising each factor, we offer an alternative interpretation of the factors. Findings also indicate that one factor, which is generally not assessed in clinical neuropsychology settings, may be more predictive of real-world behaviors (such as medication adherence) than those composed of traditional measures. Suggestions for further research in this important area are discussed

    ECG measurement parameters of athletes are reliable when made with a smartphone based ECG device

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    Pre-participation cardiac screening including electrocardiogram (ECG) is a subject of controversy among sports medicine practitioners. Opponents of pre-participation ECG screen site concerns regarding the cost and accuracy of the testing. Recently, a single lead ECG accessory has become available for use with smartphones. The purpose of this study was to evaluate the between and within rater validity and reliability of the Kardia device in recording the ECG parameters rate, rhythm, and PR, QRS, and QT intervals. The ECG parameter made with the smartphone were also compared to same measures made using a 12 lead electrocardiograph. This investigation used a repeated measures cross-sectional design. The investigation was conducted in 2 separate phases using separate participant samples. Phase 1 (N=10) was used to determine the within rater reliability with the Kardia device. Phase 2 (N=12) was used to determine the reliability between the Kardia device and the 12 lead electrocardiograph. The between rater and between device reliability for the rate, QT interval and QRS duration parameters ranged good to very good (ICC = 0.667 – 0.981). The current investigation showed that the reliability of the ECG parameters measured using the smartphone technology ranged from good to very good. This paper serves as support for a technological advancement that will help advance the debate on the utility of ECG testing as part of the athletic pre-participation physical

    Spitzer IRAC Observations of Star Formation in N159 in the LMC

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    We present observations of the giant HII region complex N159 in the LMC using IRAC on the {\it Spitzer Space Telescope}. One of the two objects previously identified as protostars in N159 has an SED consistent with classification as a Class I young stellar object (YSO) and the other is probably a Class I YSO as well, making these two stars the youngest stars known outside the Milky Way. We identify two other sources that may also be Class I YSOs. One component, N159AN, is completely hidden at optical wavelengths, but is very prominent in the infrared. The integrated luminosity of the entire complex is L 9×106\approx 9\times10^6L_{\odot}, consistent with the observed radio emission assuming a normal Galactic initial mass function (IMF). There is no evidence for a red supergiant population indicative of an older burst of star formation. The N159 complex is 50 pc in diameter, larger in physical size than typical HII regions in the Milky Way with comparable luminosity. We argue that all of the individual components are related in their star formation history. The morphology of the region is consistent with a wind blown bubble $\approx 1-2Myr-old that has initiated star formation now taking place at the rim. Other than its large physical size, star formation in N159 appears to be indistinguishable from star formation in the Milky Way.Comment: 14 figure

    Outflows from Luminous YSOs: An Infrared Polarimetric Study

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    e present Near Infrared imaging polarimetry of three regions of massive star formation, G192.163.82192.16 - 3.82, Cepheus A, and W42. In W42 we have discovered a new bipolar nebula located at the far side of the HII region behind the visible cluster of exciting stars. The axis of this new nebula is aligned with the magnetic field threading the entire cluster region. Polarization in the bipolar outflow nebulosity associated with G192.16 is consistent with a single illuminating source, too faint to be detected at 2 \micron. Polarization in the reflection nebulosity associated with Ceph A requires more than one illuminating source, although HW2 is clearly dominant. In all three objects, the magnetic field in the outflow at distances greater than 0.2\sim 0.2 pc is radial. In G192.16 the magnetic field geometry closer than 0.2\sim 0.2 pc to the embedded star appears chaotic. For G192.16 the outflow is not aligned with the surrounding magnetic field, which lies in the galactic plane. In Ceph A, the outflow axis could be interpreted as being aligned with the galactic plane, but the magnetic field threading the region is not. Only in the case of W42 is the magnetic field threading the HII region aligned with the mean field in the surrounding galactic plane.Comment: 1 LaTeX file, 10 figure

    The Hemocompatibility of a Nitric Oxide Generating Polymer that Catalyzes S-nitrosothiol Decomposition in an Extracorporeal Circulation Model

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    Nitric oxide (NO) generating (NOGen) materials have been shown previously to create localized increases in NO concentration by the catalytic decomposition of blood S-nitrosothiols (RSNO) via copper (Cu)-containing polymer coatings and may improve extracorporeal circulation (ECC) hemocompatibility. In this work, a NOGen polymeric coating composed of a Cuo-nanoparticle (80 nm)-containing hydrophilic polyurethane (SP-60D-60) combined with the intravenous infusion of an RSNO, S- nitroso-N-acetylpenicillamine (SNAP), is evaluated in a 4 h rabbit thrombogenicity model and the anti-thrombotic mechanism is investigated. Polymer films containing 10 wt.% Cuo-nanoparticles coated on the inner walls of ECC circuits are employed concomitantly with systemic SNAP administration (0.1182 μmol/kg/min) to yield significantly reduced ECC thrombus formation compared to polymer control + systemic SNAP or 10 wt.% Cu NOGen + systemic saline after 4 h blood exposure (0.4 ± 0.2 NOGen/SNAP vs 4.9 ± 0.5 control/SNAP or 3.2 ± 0.2 pixels/cm2 NOGen/saline). Platelet count (3.9 ± 0.7 NOGen/SNAP vs 1.8 ± 0.1 control/SNAP or 3.0 ± 0.2 × 108/ml NOGen/saline) and plasma fibrinogen levels were preserved after 4 h blood exposure with the NOGen/SNAP combination vs either the control/SNAP or the NOGen/saline groups. Platelet function as measured by aggregometry (51 ± 9 NOGen/SNAP vs 49 ± 3% NOGen/saline) significantly decreased in both the NOGen/SNAP and NOGen/saline groups while platelet P-selectin mean fluorescence intensity (MFI) as measured by flow cytometry was not decreased after 4 h on ECC to ex vivo collagen stimulation (26 ± 2 NOGen/SNAP vs 29 ± 1 MFI baseline). Western blotting showed that fibrinogen activation as assessed by Aγ dimer expression was reduced after 4 h on ECC with NOGen/SNAP (68 ± 7 vs 83 ± 3% control/SNAP). These results suggest that the NOGen polymer coating combined with SNAP infusion preserves platelets in blood exposure to ECCs by attenuating activated fibrinogen and preventing platelet aggregation. These NO-mediated platelet changes were shown to improve thromboresistance of the NOGen polymer-coated ECCs when adequate levels of RSNOs are present
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