3,901 research outputs found

    The Shapes of Dense Cores and Bok Globules

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    The shapes of isolated Bok globules and embedded dense cores of molecular clouds are analyzed using a nonparametric method, under the alternate hypotheses that they are randomly oriented prolate objects or that they are randomly oriented oblate objects. In all cases, the prolate hypothesis gives a better fit to the data. If Bok globules are oblate, they must be very flat; the average axis ratio is b/a = 0.3, and few or no globules can have b/a > 0.7. If Bok globules are prolate, then the mean axis ratio is b/a = 0.5. For most data samples of dense cores, the randomly-oriented oblate hypothesis can be rejected at the 99% confidence level. If the dense cores are prolate, their mean axis ratio is approximately 0.4 to 0.5. Dense cores are significantly different in shape from the clouds in which they are embedded; clouds have flatter apparent shapes, and are inconsistent with a population of randomly oriented axisymmetric objects.Comment: 26 pages (LaTeX) including 8 postscript figures; to appear in Ap

    Earnings distribution, corporate governance and CEO pay

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    We investigate the relationship between earnings differentials and the pay of CEOs of 190 British companies between 1970 and 1990. We find that (i) changes in the differential between the 90th and 50th weekly earnings percentiles for non-manual adult male workers [90:50] explain changes in the level of real CEO salary and bonus in our sample of companies; (ii) changes in this differential also account for changes in the elasticity of CEO pay to firm size; (iii) a broader measure of earnings inequality does far worse than 90:50 at explaining changes in both the level and the firm size elasticity of CEO pay; (iv) fitting the model on data for 1970-1983 and predicting pay levels for the period starting with the widespread adoption of executive share option schemes in 1984, we find a structural break in the relationship between lower management pay differentials and the pay of the CEO. We conclude first that top executive pay prior to 1984 was a stable function of both firm size and earnings differentials lower on the administrative ladder, consistent with a hypothesis advanced by Herbert Simon in 1957; and second that the use of share options from 1984 onward represents not simply a change in the mode of top executive compensation, but a de -linking of the pay of top executives and that of their subordinates

    Recombinant monovalent llama-derived antibody fragments (VHH) to rotavirus VP6 protect neonatal gnotobiotic piglets against human rotavirus-induced diarrhea

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    Group A Rotavirus (RVA) is the leading cause of severe diarrhea in children. The aims of the present study were to determine the neutralizing activity of VP6-specific llama-derived single domain nanoantibodies (VHH nanoAbs) against different RVA strains in vitro and to evaluate the ability of G6P[1] VP6-specific llama-derived single domain nanoantibodies (VHH) to protect against human rotavirus in gnotobiotic (Gn) piglets experimentally inoculated with virulent Wa G1P[8] rotavirus. Supplementation of the daily milk diet with 3B2 VHH clone produced using a baculovirus vector expression system (final ELISA antibody -Ab- titer of 4096; virus neutralization -VN- titer of 256) for 9 days conferred full protection against rotavirus associated diarrhea and significantly reduced virus shedding. The administration of comparable levels of porcine IgG Abs only protected 4 out of 6 of the animals from human RVA diarrhea but significantly reduced virus shedding. In contrast, G6P[1]-VP6 rotavirus-specific IgY Abs purified from eggs of hyperimmunized hens failed to protect piglets against human RVA-induced diarrhea or virus shedding when administering similar quantities of Abs. The oral administration of VHH nanoAb neither interfered with the host's isotype profiles of the Ab secreting cell responses to rotavirus, nor induced detectable host Ab responses to the treatment in serum or intestinal contents. This study shows that the oral administration of rotavirus VP6-VHH nanoAb is a broadly reactive and effective treatment against rotavirus-induced diarrhea in neonatal pigs. Our findings highlight the potential value of a broad neutralizing VP6-specific VHH nanoAb as a treatment that can complement or be used as an alternative to the current strain-specific RVA vaccines. Nanobodies could also be scaled-up to develop pediatric medication or functional food like infant milk formulas that might help treat RVA diarrhea.Fil: Vega, Celina Guadalupe. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bok, Marina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vlasova, Anastasia N.. Ohio State University; Estados UnidosFil: Chattha, Kuldeep S.. Ohio State University; Estados UnidosFil: Gómez Sebastián, Silvia. Universidad Politécnica de Madrid; EspañaFil: Nuñez, Carmen. Universidad Politécnica de Madrid; EspañaFil: Alvarado, Carmen. Universidad Politécnica de Madrid; EspañaFil: Lasa, Rodrigo. Universidad Politécnica de Madrid; EspañaFil: Escribano, José M.. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Departamento Mejora Genética y Biotecnología; EspañaFil: Garaicoechea, Lorena Laura. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernández, Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; ArgentinaFil: Bok, Karin. National Institutes of Health; Estados UnidosFil: Wigdorovitz, Andrés. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Saif, Linda J.. Ohio State University; Estados UnidosFil: Parreño, Gladys Viviana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Methicillin resistant S. aureus (MRSA) and their antibiotic sensitivity pattern in Kano, Nigeria

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    Background: Nosocomial infection caused by methicillin resistant S. aureus (MRSA) presents with management difficulties in infected patients due to their resistance to a number of other frontline antibiotics and constitutessignificant epidemiological problems. This study was undertaken to determine the prevalence of methicillin resistant S. aureus and antibiotic sensitivity pattern in clinical isolates in Kano. There is dearth of  information onthis subject in Kano.Method: One hundred and eighty five (185) S. aureus isolates from various clinical specimens obtained over a 12-month period in the Microbiology Department of Aminu Kano Teaching Hospital (AKTH) were subjected to methicillin susceptibility testing, while including susceptibility testing to other antibiotics by the disc diffusion methods.Result: Out of 185 S. aureus isolates tested, 53(28.6%) were found to be methicillin resistant. While 38(62%) isolates were obtained from in-patients, 15(28%) were from out-patients. Surgical wound infection had the highest prevalence of 32(60%) isolates. Antibiotics sensitivity results of methicillin susceptible staphylococcus aureus MSSA) and MRSA with the third generation cephalosporins and the quinilones were encouraging. AllMRSA isolates were sensitive to vancomycin.Conclusion: A prevalence of 28.6% MRSA in this environment calls for urgent intervention strategies due to its possible rapid spread and therapeutic problem

    Quaking Aspen Ecology on Forest Service Lands North of Yellowstone National Park

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    Quaking aspen (Populus tremuloides) occupy a small area in the northern Rocky Mountains, but are highly valued as wildlife habitat. Aspen stands in and around Yellowstone National Park commonly consist of few, large, mature overstory stems and numerous root suckers that do not grow above the browsing reach (≈ 2 m) of most wild ungulates. Our primary objective was to determine if the recruitment or density of aspen stems \u3e 2 m tall had changed from 1991 to 2006 on a portion of the Gallatin National Forest. The same aspen stands were surveyed in 1991 and 2006 in the 560 km² study area (n = 316). Secondary objectives were to determine if aspen density was influenced by elk (Cervus elaphus) browsing, conifer establishment, and cattle (Bos spp.) grazing. Mean recruitment stem density did not change from 1991 to 2006 (P = 0.95). Density of stems \u3e 2 m declined 12 percent from 1991 to 2006 (P = 0.04), which indicates that recruitment stems are not being produced at a sufficient rate to replace aging overstories. Areas with the greatest elk densities had the lowest recruitment stem densities and contributed the most to the decline. Although elk browsing seemed to play the largest role, conifer establishment and cattle grazing have also negatively impacted overstory recruitment in aspen stands. Even though elk numbers on the Northern Yellowstone Winter Range have declined since wolf reintroduction, aspen recruitment has not increased at the landscape level on the Gallatin National Forest

    Analyse de la variabilité germinative de la vesce commune sous l’impact d’un stress Ferrique-Cadmique-Salin

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    Ce travail a pour but de voir l’impact de l’application d’une combinaison de stress abiotique sur la germination des graines de vesce commune ainsi que de visualiser les modifications physiologiques et histologiques au niveau des tissus racinaires sous l’influence de ces contraintes. De ce fait, une conduite de germination a été réalisée avec des graines de vesce commune dans différentes situations de combinaisons entre trois types de stress métallique-cadmique-salin et un suivi a été fait en se basant sur des caractères végétatifs bien déterminés. Les résultats montrent bien une nette différence entre les réponses des graines à l’application de stress séparément et entre les combinaisons de stress ainsi qu’une variabilité intra-espèce énorme vis-à-vis de différentes types de contraintes.Mots-clés : vesce commune, stress métallique-cadmique-salin, caractères végétatifs, modifications physiologiques et histologiques

    Persistence of insecticidal activity of novel bio-encapsulated formulations of Bacillus thuringiensis var. kurstaki against Choristoneura rosaceana [Lepidoptera: Tortricidae]

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    Le DiPelTM, une formulation commerciale du Bacillus thuringiensis var. kurstaki (Btk), et des formulations bio-encapsulées du Btk ont été pulvérisées dans un verger de pommiers. Pendant trois années consécutives, leur persistance a été évaluée en laboratoire sur des larves de tordeuse à bandes obliques (Choristoneura rosaceana). En 1995, le DiPel et la formulation bio-encapsulée ont causé une mortalité larvaire significativement plus grande que celle du témoin, au moins 1 jour et jusqu’à 27 jours après les traitements, respectivement. En 1996, bien que 6 mm de pluie soient tombés la journée des traitements, le DiPel et la formulation bio-encapsulée ont causé respectivement 21 et 33 % de mortalité larvaire immédiatement après les traitements. Le DiPel a causé une mortalité significativement plus grande que celle du témoin pour une période de trois jours après les traitements alors que la formulation bio-encapsulée a causé une mortalité plus grande pendant 14 jours. En 1997, deux souches de Btk (HD-1 et BMP123) ont été pulvérisées à des concentrations différentes en matière active (3 et 8 %) et en doses (30 et 240 g 15 L-1). Des concentrations élevées en matière active et des doses élevées ont accru la persistance de l’activité insecticide des formulations de Btk. Parmi les facteurs météorologiques mesurés (précipitations, température et radiations solaires), les précipitations ont réduit la persistance de l’activité insecticide. Les radiations solaires peuvent également avoir contribué à moduler la persistance des formulations.DiPelTM, a registered Bacillus thuringiensis var. kurstaki (Btk)-based formulation, and experimental bio-encapsulated Btk formulations were sprayed in an apple orchard. Their persistence was assessed in the laboratory against obliquebanded leafroller (Choristoneura rosaceana) larvae for three consecutive years. In 1995, DiPel and the bio-encapsulated formulation caused significantly higher larval mortality than the control at least 1 day, and up to 27 days after treatments, respectively. In 1996, although 6.4 mm of rain fell during the day of treatments, DiPel and the bio-encapsulated formulation caused respectively 21 and 33% larval mortality immediately after treatments. DiPel caused significantly higher mortality than the control for up to 3 days while the bio-encapsulated formulation caused significantly higher mortality for up to 14 days. In 1997, two Btk strains (HD-1 and BMP123) were sprayed at different concentrations in a.i. (3 and 8%) and doses (30 and 240 g 15 L-1 applied). Higher concentrations of a.i. in the Btk formulations and higher doses sprayed increased the persistence of the insecticidal activity. Among the meteorological factors that were measured (i.e. precipitations, temperature and solar radiations), precipitations reduced the persistence of the insecticidal activity. Solar radiations may have modulated the persistence of the formulations

    Joint Blind Motion Deblurring and Depth Estimation of Light Field

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    Removing camera motion blur from a single light field is a challenging task since it is highly ill-posed inverse problem. The problem becomes even worse when blur kernel varies spatially due to scene depth variation and high-order camera motion. In this paper, we propose a novel algorithm to estimate all blur model variables jointly, including latent sub-aperture image, camera motion, and scene depth from the blurred 4D light field. Exploiting multi-view nature of a light field relieves the inverse property of the optimization by utilizing strong depth cues and multi-view blur observation. The proposed joint estimation achieves high quality light field deblurring and depth estimation simultaneously under arbitrary 6-DOF camera motion and unconstrained scene depth. Intensive experiment on real and synthetic blurred light field confirms that the proposed algorithm outperforms the state-of-the-art light field deblurring and depth estimation methods

    Deep Depth From Focus

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    Depth from focus (DFF) is one of the classical ill-posed inverse problems in computer vision. Most approaches recover the depth at each pixel based on the focal setting which exhibits maximal sharpness. Yet, it is not obvious how to reliably estimate the sharpness level, particularly in low-textured areas. In this paper, we propose `Deep Depth From Focus (DDFF)' as the first end-to-end learning approach to this problem. One of the main challenges we face is the hunger for data of deep neural networks. In order to obtain a significant amount of focal stacks with corresponding groundtruth depth, we propose to leverage a light-field camera with a co-calibrated RGB-D sensor. This allows us to digitally create focal stacks of varying sizes. Compared to existing benchmarks our dataset is 25 times larger, enabling the use of machine learning for this inverse problem. We compare our results with state-of-the-art DFF methods and we also analyze the effect of several key deep architectural components. These experiments show that our proposed method `DDFFNet' achieves state-of-the-art performance in all scenes, reducing depth error by more than 75% compared to the classical DFF methods.Comment: accepted to Asian Conference on Computer Vision (ACCV) 201
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