3,121 research outputs found

    Business strategy and firm performance: the British corporate economy, 1949-1984

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    There has been considerable and ongoing debate about the performance of the British economy since 1945. Empirical studies have concentrated on aggregate or industry level indicators. Few have examined individual firms’ financial performance. This study takes a sample of c.3000 firms in 19 industries and identifies Britain’s best performing companies over a period of 35 years. Successful companies are defined as a) those that survive as independent entities, b) that outperform peer group average return to capital for that industry, and c) that outperform other firms in the economy according to return on capital relative to industry average. Results are presented as league tables of success and some tentative explanations offered concerning the common strategies of successful firms. A broader research agenda for British business history is suggested

    A diagnostic plot for assessing model fit incount data models

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    Whilst many numeric methods, such as AIC and deviance, exist for assessing model fit, diagrammatic methods are few. We present here a diagnostic plot, to which we refer as ‘Christmas tree plot’ due its characteristic shape, that may be used to visually assess the suitability of a given count data model

    On statistical testing and mean parameter estimation for zero–modification in count data regression

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    For the problem of testing for zero–modification in Poisson regression, a simple and intuitive test can be constructed by computing directly confidence intervals for the number of 0’s under the Poisson assumption. This requires the ability of estimating the mean function accurately even if the data are in fact zero–inflated or deflated. A novel hybrid estimator is introduced for this purpose, which is of interest beyond the scope of the motivating test problem

    A diagnostic plot for assessing model fit in count data models

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    Whilst many numeric methods, such as AIC and deviance, exist for assessing model fit, diagrammatic methods are few. We present here a diagnostic plot, to which we refer as `Christmas tree plot' due its characteristic shape, that may be used to visually assess the suitability of a given count data model

    Immunocytochemical localization of protein kinase C in resting and activated human neutrophils

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    AbstractAn immunocytochemical method was used to determine possible changes in the subcellular distribution of protein kinase C (PKC) in human neutrophils in response to opsonized latex beads and zymosan. While in resting cells most of the PKC immunoreactivity was localized in the cytoplasm, a redistribution of PKC to the plasma and phagosomal membranes was observed in cells treated with latex beads or zymosan for 5–20 min, suggesting a participation of PKC in endocytosis

    Pulmonary Hydatid Cyst with Complicating Aspergillus Infection Presenting as a Refractory Lung Abscess

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    Background Hydatid disease is rare in the United States. Rarely the hydatid cyst can become infected with mycotic organisms, such as Aspergillus . We describe a young male who presents with clinical features of suppurative lung abscess whose workup diagnosed hydatid cyst complicated by Aspergillus co-infection. Case presentation A 27-year-old Peruvian male was hospitalized because of fever, chills, and productive cough of three months’ duration. Clinical features were consistent with a suppurative lung abscess. Significant findings included leukocytosis with eosinophilia and a chest x-ray showing a large lingular lobe thick walled cavity with a wavy irregular fluid level. The patient ultimately underwent surgical resection of the lingular lobe. Examination of the surgical specimen revealed the cavity to be a hydatid cyst. Histologic examination of the cyst wall showed intense inflammation and several septate hyphae of Aspergillus species. The patient recovered fully and has remained in good health. Conclusion A thick-walled cavity and a wavy meniscus constitute unusual features for an ordinary pyogenic lung abscess and suggests other possibilities. Endogenous cases of hydatid disease are uncommon in the United States, with the majority of cases occurring in immigrants. There are few published case reports describing incidental findings of Aspergillus in a hydatid cyst. The rare occurrence of such a condition can lead to a delay in diagnosis and treatment

    Extensions of discrete classical orthogonal polynomials beyond the orthogonality

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    It is well known that the family of Hahn polynomials {hnα,β(x;N)}n≥0\{h_n^{\alpha,\beta}(x;N)\}_{n\ge 0} is orthogonal with respect to a certain weight function up to NN. In this paper we present a factorization for Hahn polynomials for a degree higher than NN and we prove that these polynomials can be characterized by a Δ\Delta-Sobolev orthogonality. We also present an analogous result for dual-Hahn, Krawtchouk, and Racah polynomials and give the limit relations between them for all n\in \XX N_0. Furthermore, in order to get this results for the Krawtchouk polynomials we will get a more general property of orthogonality for Meixner polynomials.Comment: 2 figures, 20 page

    Potential for Supernova Neutrino Detection in MiniBooNE

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    The MiniBooNE detector at Fermilab is designed to search for νμ→νe\nu_\mu \to \nu_e oscillation appearance at Eν∼1GeVE_\nu \sim 1 {\rm GeV} and to make a decisive test of the LSND signal. The main detector (inside a veto shield) is a spherical volume containing 0.680 ktons of mineral oil. This inner volume, viewed by 1280 phototubes, is primarily a \v{C}erenkov medium, as the scintillation yield is low. The entire detector is under a 3 m earth overburden. Though the detector is not optimized for low-energy (tens of MeV) events, and the cosmic-ray muon rate is high (10 kHz), we show that MiniBooNE can function as a useful supernova neutrino detector. Simple trigger-level cuts can greatly reduce the backgrounds due to cosmic-ray muons. For a canonical Galactic supernova at 10 kpc, about 190 supernova νˉe+p→e++n\bar{\nu}_e + p \to e^+ + n events would be detected. By adding MiniBooNE to the international network of supernova detectors, the possibility of a supernova being missed would be reduced. Additionally, the paths of the supernova neutrinos through Earth will be different for MiniBooNE and other detectors, thus allowing tests of matter-affected mixing effects on the neutrino signal.Comment: Added references, version to appear in PR
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