1,061 research outputs found

    Perspectives on the sources of heterogeneity in Indian industry

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    The authors examine technical efficiency variation across four industrial sectors in India, using a stochastic production frontier technique. The results are comparable to technical efficiency distribution patterns obtained in other countries. The authors examine heterogeneity in firm-level efficiency against internal, firm-level characteristics and against external characteristics (industry and location). The results suggest that managerial effectiveness significantly influences efficiency and that considerable benefits derive from location within established industrial clusters for particular industries. The methodology and findings indicate that the study of industry-specific technical efficiency patterns is a useful analytical tool for tracking domestic firms'response to liberalization and the advance of market forces. An important policy implication of the authors'results: There is considerable room for efficiency gains through better organization and management of production processes and improved supply chain management, even in the highly organized corporate sector. These gains could be achieved by purely internal learning processes with no extra investment in physical plant or equipment, or with the help of outside consultants, or through business alliances with partners from industrial countries (a rising trend). The results also show that greater technical efficiency correlates with better energy use and higher investments in plant management. How firms can be induced to undertake such investments in the"software"of production is an important issue. Liberalization and globalization are likely to bring significant productivity gains even in low-technology industries as managers gear up to meet the challenges of competition.Environmental Economics&Policies,Water and Industry,Health Monitoring&Evaluation,Economic Theory&Research,Banks&Banking Reform

    Shark: introducing an open source, free and flexible semi-analytic model of galaxy formation

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    We present a new, open source, free semi-analytic model (SAM) of galaxy formation, Shark, designed to be highly flexible and modular, allowing easy exploration of different physical processes and ways of modelling them. We introduce the philosophy behind Shark and provide an overview of the physical processes included in the model. Shark is written in C++11 and has been parallelized with OpenMP. In the released version (v1.1), we implement several different models for gas cooling, active galactic nuclei, stellar and photo-ionisation feedback, and star formation (SF). We demonstrate the basic performance of Shark using the Planck15 cosmology SURFS simulations, by comparing against a large set of observations, including: the stellar mass function (SMF) and stellar-halo mass relation at z=0-4; the cosmic evolution of the star formation rate density (SFRD), stellar mass, atomic and molecular hydrogen; local gas scaling relations; and structural galaxy properties, finding excellent agreement. Significant improvements over previous SAMs are seen in the mass-size relation for disks/bulges, the gas-stellar mass and stellar mass-metallicity relations. To illustrate the power of Shark in exploring the systematic effects of the galaxy formation modelling, we quantify how the scatter of the SF main sequence and the gas scaling relations changes with the adopted SF law, and the effect of the starbursts H2_2 depletion timescale on the SFRD and ΩH2\Omega_{\rm H_2}. We compare Shark with other SAMs and the hydrodynamical simulation EAGLE, and find that SAMs have a much higher halo baryon fractions due to large amounts of intra-halo gas, which in the case of EAGLE is in the intergalactic medium.Comment: Final MNRAS version of accepted pape

    Tidal Energy Round Robin Tests: A Comparison of Flow Measurements and Turbine Loading

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    A Round Robin Tests program is being undertaken within the EC MaRINET2 initiative. This programme studies the used facility influence can have on the performance evaluation of a horizontal axis tidal turbine prototype when it is operated under wave and current conditions. In this paper, we present the design of experiments that is used throughout the work programme and the results related to the flow characterisation obtained at the Ifremer wave and current circulating tank, the Cnr-Inm wave towing tank and the ocean research facility FloWave. These facilities have been identified to provide adequate geometric conditions to accommodate a 0.724 m diameter turbine operating at flow velocities of 0.8 and 1.0 m/s. The set-up is replicated in each of the facilities with exemption of the amount of flow measuring instruments. Intrinsic differences in creating wave and currents between facilities are found. Flow velocities are up to 10% higher than the nominal values and wave amplitudes higher than the target values by up to a factor of 2. These discrepancies are related to the flow and wave generation methods used at each facility. When the flow velocity is measured besides the rotor, the velocity presents an increase of 8% compared to the upstream measurements

    Quenching massive galaxies across cosmic time with the semi-analytic model SHARK v2.0

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    We introduce version 2.0 of the SHARK semi-analytic model of galaxy formation after many improvements to the physics included. The most significant being: (i) a model describing the exchange of angular momentum (AM) between the interstellar medium and stars; (ii) a new active galactic nuclei feedback model which has two modes, a quasar and a radio mode, with the radio mode tied to the jet energy production; (iii) a model tracking the development of black hole (BH) spins; (iv) more sophisticated modelling of environmental effects on satellite galaxies; and (v) automatic parameter exploration using Particle Swarm Optimisation. We focus on two timely research topics: the structural properties of galaxies and the quenching of massive galaxies. For the former, SHARK v2.0 is capable of producing a more realistic stellar size-mass relation with a plateau marking the transition from disk- to bulge-dominated galaxies, and scaling relations between specific AM and mass that agree well with observations. For the quenching of massive galaxies, SHARK v2.0 produces massive galaxies that are more quenched than the previous version, reproducing well the observed relations between star formation rate (SFR) and stellar mass, and specific SFR and BH mass at z=0z=0. SHARK v2.0 produces a number density of massive-quiescent galaxies >1dex higher than the previous version, in good agreement with JWST observations at z≤5z\le 5; predicts a stellar mass function of passive galaxies in reasonably good agreement with observations at 0.5<z<50.5<z<5; and environmental quenching to already be effective at z=5z=5.Comment: Submitted for publication in MNRAS. Supplementary material with additional comparisons with observations can be found here https://clagos.com/files/Shark_v2_SupplementaryMaterial.pd

    G6PD deficiency alleles in a malaria-endemic region in the Western Brazilian Amazon.

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    BACKGROUND: Plasmodium vivax parasites are the predominant cause of malaria infections in the Brazilian Amazon. Infected individuals are treated with primaquine, which can induce haemolytic anaemia in glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals and may lead to severe and fatal complications. This X-linked disorder is distributed globally and is caused by allelic variants with a geographical distribution that closely reflects populations exposed historically to endemic malaria. In Brazil, few studies have reported the frequency of G6PD deficiency (G6PDd) present in malaria-endemic areas. This is particularly important, as G6PDd screening is not currently performed before primaquine treatment. The aim of this study was to determine the prevalence of G6PDd in the region of Alto do Juruá, in the Western Brazilian Amazon, an area characterized by a high prevalence of P. vivax infection. METHODS: Five-hundred and sixteen male volunteers were screened for G6PDd using the fluorescence spot test (Beutler test) and CareStart™ G6PD Biosensor system. Demographic and clinical-epidemiological data were acquired through an individual interview. To assess the genetic basis of G6PDd, 24 SNPs were genotyped using the Kompetitive Allele Specific PCR assay. RESULTS: Twenty-three (4.5%) individuals were G6PDd. No association was found between G6PDd and the number of malaria cases. An increased risk of reported haemolysis symptoms and blood transfusions was evident among the G6PDd individuals. Twenty-two individuals had the G6PDd A(-) variant and one the G6PD A(+) variant. The Mediterranean variant was not present. Apart from one polymorphism, almost all SNPs were monomorphic or with low frequencies (0-0.04%). No differences were detected among ethnic groups. CONCLUSIONS: The data indicates that ~1/23 males from the Alto do Juruá could be G6PD deficient and at risk of haemolytic anaemia if treated with primaquine. G6PD A(-) is the most frequent deficiency allele in this population. These results concur with reported G6PDd in other regions in Brazil. Routine G6PDd screening to personalize primaquine administration should be considered, particularly as complete treatment of patients with vivax malaria using chloroquine and primaquine, is crucial for malaria elimination

    The biting performance of Homo sapiens and Homo heidelbergensis

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    Modern humans have smaller faces relative to Middle and Late Pleistocene members of the genus Homo. While facial reduction and differences in shape have been shown to increase biting efficiency in Homo sapiens relative to these hominins, facial size reduction has also been said to decrease our ability to resist masticatory loads. This study compares crania of Homo heidelbergensis and H. sapiens with respect to mechanical advantages of masticatory muscles, force production efficiency, strains experienced by the cranium and modes of deformation during simulated biting. Analyses utilize X-ray computed tomography (CT) scan-based 3D models of a recent modern human and two H. heidelbergensis. While having muscles of similar cross-sectional area to H. heidelbergensis, our results confirm that the modern human masticatory system is more efficient at converting muscle forces into bite forces. Thus, it can produce higher bite forces than Broken Hill for equal muscle input forces. This difference is the result of alterations in relative in and out-lever arm lengths associated with well-known differences in midfacial prognathism. Apparently at odds with this increased efficiency is the finding that the modern human cranium deforms more, resulting in greater strain magnitudes than Broken Hill when biting at the equivalent tooth. Hence, the facial reduction that characterizes modern humans may not have evolved as a result of selection for force production efficiency. These findings provide further evidence for a degree of uncoupling between form and function in the masticatory system of modern humans. This may reflect the impact of food preparation technologies. These data also support previous suggestions that differences in bite force production efficiency can be considered a spandrel, primarily driven by the midfacial reduction in H. sapiens that occurred for other reasons. Midfacial reduction plausibly resulted in a number of other significant changes in morphology, such as the development of a chin, which has itself been the subject of debate as to whether or not it represents a mechanical adaptation or a spandrel

    The evolutionary history of the human face

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    The face is the most distinctive feature used to identify others. Modern humans have a short, retracted face beneath a large globular braincase that is distinctively different from that of our closest living relatives. The face is a skeletal complex formed by 14 individual bones that houses parts of the digestive, respiratory, visual and olfactory systems. A key to understanding the origin and evolution of the human face is analysis of the faces of extinct taxa in the hominin clade over the last 6 million years. Yet, as new fossils are recovered and the number of hominin species grows, the question of how and when the modern human face originated remains unclear. By examining key features of the facial skeleton, here we evaluate the evolutionary history of the modern human face in the context of its development, morphology and function, and suggest that its appearance is the result of a combination of biomechanical, physiological and social influences
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