333 research outputs found

    Observational Study Design in Veterinary Pathology, Part 1: Study Design

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    Observational studies are the basis for much of our knowledge of veterinary pathology and are highly relevant to the daily practice of pathology. However, recommendations for conducting pathology-based observational studies are not readily available. In part 1 of this series, we offer advice on planning and conducting an observational study with examples from the veterinary pathology literature. Investigators should recognize the importance of creativity, insight, and innovation in devising studies that solve problems and fill important gaps in knowledge. Studies should focus on specific and testable hypotheses, questions, or objectives. The methodology is developed to support these goals. We consider the merits and limitations of different types of analytic and descriptive studies, as well as of prospective vs retrospective enrollment. Investigators should define clear inclusion and exclusion criteria and select adequate numbers of study subjects, including careful selection of the most appropriate controls. Studies of causality must consider the temporal relationships between variables and the advantages of measuring incident cases rather than prevalent cases. Investigators must consider unique aspects of studies based on archived laboratory case material and take particular care to consider and mitigate the potential for selection bias and information bias. We close by discussing approaches to adding value and impact to observational studies. Part 2 of the series focuses on methodology and validation of methods

    Observational Study Design in Veterinary Pathology, Part 2: Methodology

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    Observational studies are a basis for much of our knowledge of veterinary pathology, yet considerations for conducting pathology-based observational studies are not readily available. In part 1 of this series, we offered advice on planning and carrying out an observational study. Part 2 of the series focuses on methodology. Our general recommendations are to consider using already-validated methods, published guidelines, data from primary sources, and quantitative analyses. We discuss 3 common methods in pathology research—histopathologic scoring, immunohistochemistry, and polymerase chain reaction—to illustrate principles of method validation. Some aspects of quality control include use of clear objective grading criteria, validation of key reagents, assessing sample quality, determining specificity and sensitivity, use of technical and biologic negative and positive controls, blinding of investigators, approaches to minimizing operator-dependent variation, measuring technical variation, and consistency in analysis of the different study groups. We close by discussing approaches to increasing the rigor of observational studies by corroborating results with complementary methods, using sufficiently large numbers of study subjects, consideration of the data in light of similar published studies, replicating the results in a second study population, and critical analysis of the study findings

    Common Threats and Managing Reputation in Executive Search Firms

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    A free video abstract to accompany this article can be found online at: https://www.youtube.com/watch?v=IziwDorbeGU This paper provides important insights into how executive search firms can successfully manage their reputations to overcome major threats to their organizations. The paper focuses on three threats faced by executive search firms: the global financial crisis; questions around the sector's professional status; and the proliferation of social media for recruitment. Our data show that there was not a single coherent response from firms, but a piecemeal approach that focused on three forms of reputation management. First, diversifying service offerings; second, highlighting their symbolic capital; and third, connecting their firms to clients and candidates through partners. Building on our data and the theoretical literature, we provide a framework for understanding how professional service firms can manage their reputations in response to common threats, based on three categories from the English idiom ‘keep up with the Joneses’. First, moving away from the Joneses; second, fencing out the Joneses; third, networking more than the Joneses. We provide theoretical and practical insights around how organizations can manage their reputations in response to threats which are common across sectors

    Vivienne Westwood and the ethics of consuming fashion

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    Our paper examines ethical consumption using the case study of Vivienne Westwood, the fashion designer, and her eponymous firm, and shows how consumers of fashion might be considered ethical. The fashion industry has figured prominently in ethical debates, notably its role in encouraging overconsumption of resources and promoting an idealised lifestyle that is often neither materially nor psychically sustainable for consumers (Buchholz, 1998). We acknowledge this, yet suggest the purchase and use of clothing carries with it the potential to be ethical insofar as customers find themselves personally implicated with and caring for a designers' work

    Vaccines for the Leishmaniases: Proposals for a Research Agenda

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    The International Symposium on Leishmaniasis Vaccines, held in Olinda, Brazil, on March 9–11, 2009, congregated international experts who conduct research on vaccines against the leishmaniases. The questions that were raised during that meeting and the ensuing discussions are compiled in this report and may assist in guiding a research agenda. A group to further discussion on issues raised in this policy platform has been set up at http://groups.google.com/group/leishvaccines-l

    Managing formalization to increase global team effectiveness and meaningfulness of work in multinational organizations

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    Global teams may help to integrate across locations, and yet, with formalized rules and procedures, responsiveness to those locations’ effectiveness, and the team members’ experiences of work as meaningful may suffer. We employ a mixed-methods approach to understand how the level and content of formalization can be managed to resolve these tensions in multinationals. In a sample of global teams from a large mining and resources organization operating across 44 countries, interviews, observations, and a quantitative 2-wave survey revealed a great deal of variability between teams in how formalization processes were enacted. Only those formalization processes that promoted knowledge sharing were instrumental in improving team effectiveness. Implementing rules and procedures in the set-up of the teams and projects, rather than during interactions, and utilizing protocols to help establish the global team as a source of identity increased this knowledge sharing. Finally, we found members’ personal need for structure moderated the effect of team formalization on how meaningful individuals found their work within the team. These findings have significant implications for theory and practice in multinational organizations

    Regulation of immunity during visceral Leishmania infection

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    Unicellular eukaryotes of the genus Leishmania are collectively responsible for a heterogeneous group of diseases known as leishmaniasis. The visceral form of leishmaniasis, caused by L. donovani or L. infantum, is a devastating condition, claiming 20,000 to 40,000 lives annually, with particular incidence in some of the poorest regions of the world. Immunity to Leishmania depends on the development of protective type I immune responses capable of activating infected phagocytes to kill intracellular amastigotes. However, despite the induction of protective responses, disease progresses due to a multitude of factors that impede an optimal response. These include the action of suppressive cytokines, exhaustion of specific T cells, loss of lymphoid tissue architecture and a defective humoral response. We will review how these responses are orchestrated during the course of infection, including both early and chronic stages, focusing on the spleen and the liver, which are the main target organs of visceral Leishmania in the host. A comprehensive understanding of the immune events that occur during visceral Leishmania infection is crucial for the implementation of immunotherapeutic approaches that complement the current anti-Leishmania chemotherapy and the development of effective vaccines to prevent disease.The research leading to these results has received funding from the European Community’s Seventh Framework Programme under grant agreement No.602773 (Project KINDRED). VR is supported by a post-doctoral fellowship granted by the KINDReD consortium. RS thanks the Foundation for Science and Technology (FCT) for an Investigator Grant (IF/00021/2014). This work was supported by grants to JE from ANR (LEISH-APO, France), Partenariat Hubert Curien (PHC) (program Volubilis, MA/11/262). JE acknowledges the support of the Canada Research Chair Program

    Population of Merging Compact Binaries Inferred Using Gravitational Waves through GWTC-3

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    We report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalog 3 (GWTC-3) contains signals consistent with three classes of binary mergers: binary black hole, binary neutron star, and neutron star-black hole mergers. We infer the binary neutron star merger rate to be between 10 and 1700 Gpc-3 yr-1 and the neutron star-black hole merger rate to be between 7.8 and 140 Gpc-3 yr-1, assuming a constant rate density in the comoving frame and taking the union of 90% credible intervals for methods used in this work. We infer the binary black hole merger rate, allowing for evolution with redshift, to be between 17.9 and 44 Gpc-3 yr-1 at a fiducial redshift (z=0.2). The rate of binary black hole mergers is observed to increase with redshift at a rate proportional to (1+z)κ with κ=2.9-1.8+1.7 for z≲1. Using both binary neutron star and neutron star-black hole binaries, we obtain a broad, relatively flat neutron star mass distribution extending from 1.2-0.2+0.1 to 2.0-0.3+0.3M⊙. We confidently determine that the merger rate as a function of mass sharply declines after the expected maximum neutron star mass, but cannot yet confirm or rule out the existence of a lower mass gap between neutron stars and black holes. We also find the binary black hole mass distribution has localized over- and underdensities relative to a power-law distribution, with peaks emerging at chirp masses of 8.3-0.5+0.3 and 27.9-1.8+1.9M⊙. While we continue to find that the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above approximately 60M⊙, which would indicate the presence of a upper mass gap. Observed black hole spins are small, with half of spin magnitudes below χi≈0.25. While the majority of spins are preferentially aligned with the orbital angular momentum, we infer evidence of antialigned spins among the binary population. We observe an increase in spin magnitude for systems with more unequal-mass ratio. We also observe evidence of misalignment of spins relative to the orbital angular momentum

    Constraints on dark photon dark matter using data from LIGO's and Virgo's third observing run

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    We present a search for dark photon dark matter that could couple to gravitational-wave interferometers using data from Advanced LIGO and Virgo's third observing run. To perform this analysis, we use two methods, one based on cross-correlation of the strain channels in the two nearly aligned LIGO detectors, and one that looks for excess power in the strain channels of the LIGO and Virgo detectors. The excess power method optimizes the Fourier Transform coherence time as a function of frequency, to account for the expected signal width due to Doppler modulations. We do not find any evidence of dark photon dark matter with a mass between mA10141011m_{\rm A} \sim 10^{-14}-10^{-11} eV/c2c^2, which corresponds to frequencies between 10-2000 Hz, and therefore provide upper limits on the square of the minimum coupling of dark photons to baryons, i.e. U(1)BU(1)_{\rm B} dark matter. For the cross-correlation method, the best median constraint on the squared coupling is 1.31×1047\sim1.31\times10^{-47} at mA4.2×1013m_{\rm A}\sim4.2\times10^{-13} eV/c2c^2; for the other analysis, the best constraint is 2.4×1047\sim 2.4\times 10^{-47} at mA5.7×1013m_{\rm A}\sim 5.7\times 10^{-13} eV/c2c^2. These limits improve upon those obtained in direct dark matter detection experiments by a factor of 100\sim100 for mA[24]×1013m_{\rm A}\sim [2-4]\times 10^{-13} eV/c2c^2, and are, in absolute terms, the most stringent constraint so far in a large mass range mAm_A\sim 2×10138×10122\times 10^{-13}-8\times 10^{-12} eV/c2c^2.Comment: 20 pages, 7 figure

    The population of merging compact binaries inferred using gravitational waves through GWTC-3

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    We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 Gpc3yr1\rm{Gpc^{-3} yr^{-1}} and 1700 Gpc3yr1\rm{Gpc^{-3} yr^{-1}} and the NSBH merger rate to be between 7.8 Gpc3yr1\rm{Gpc^{-3}\, yr^{-1}} and 140 Gpc3yr1\rm{Gpc^{-3} yr^{-1}} , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 Gpc3yr1\rm{Gpc^{-3}\, yr^{-1}} and 44 Gpc3yr1\rm{Gpc^{-3}\, yr^{-1}} at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from 1.20.2+0.1M1.2^{+0.1}_{-0.2} M_\odot to 2.00.3+0.3M2.0^{+0.3}_{-0.3} M_\odot. We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 MM_\odot. We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above 60M\sim 60 M_\odot. The rate of BBH mergers is observed to increase with redshift at a rate proportional to (1+z)κ(1+z)^{\kappa} with κ=2.91.8+1.7\kappa = 2.9^{+1.7}_{-1.8} for z1z\lesssim 1. Observed black hole spins are small, with half of spin magnitudes below χi0.25\chi_i \simeq 0.25. We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio
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