1,053 research outputs found

    An Evaluation of Mergers in the U.S. Petroleum Industry

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    This paper analyzes the effects of mergers and acquisitions on the profitability of both participating firms and competitor firms in the U.S. petroleum industry. It also identifies distinct economic conditions and firm specific characteristics that are correlated with the performance of the firm and the merger. The span of the study reaches from 1995-2011. It incorporates four unique, yet characteristic mergers of the domestic petroleum industry. The paper finds evidence that mergers and acquisitions affect the profitability of participating firms positively and competitor firms negatively. This study also provides insight into how uniform mergers and acquisitions in this industry may truly be

    Neutrino masses and mixings: Status of known and unknown 3ν3\nu parameters

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    Within the standard 3nu mass-mixing framework, we present an up-to-date global analysis of neutrino oscillation data (as of January 2016), including the latest available results from experiments with atmospheric neutrinos (Super-Kamiokande and IceCube DeepCore), at accelerators (first T2K anti-nu and NOvA nu runs in both appearance and disappearance mode), and at short-baseline reactors (Daya Bay and RENO far/near spectral ratios), as well as a reanalysis of older KamLAND data in the light of the "bump" feature recently observed in reactor spectra. We discuss improved constraints on the five known oscillation parameters (delta m^2, |Delta m^2|, sin^2theta_12, sin^2theta_13, sin^2theta_23), and the status of the three remaining unknown parameters: the mass hierarchy, the theta_23 octant, and the possible CP-violating phase delta. With respect to previous global fits, we find that the reanalysis of KamLAND data induces a slight decrease of both delta m^2 and sin^2theta_12, while the latest accelerator and atmospheric data induce a slight increase of |Delta m^2|. Concerning the unknown parameters, we confirm the previous intriguing preference for negative values of sin(delta) [with best-fit values around sin(delta) ~ -0.9], but we find no statistically significant indication about the theta_23 octant or the mass hierarchy (normal or inverted). Assuming an alternative (so-called LEM) analysis of NOvA data, some delta ranges can be excluded at >3 sigma, and the normal mass hierarchy appears to be slightly favored at 90% C.L. We also describe in detail the covariances of selected pairs of oscillation parameters. Finally, we briefly discuss the implications of the above results on the three non-oscillation observables sensitive to the (unknown) absolute nu mass scale: the sum of nu masses, the effective nu_e mass, and the effective Majorana mass.Comment: 15 pages, 9 figures, 2 tables. Invited contribution prepared for the Nuclear Physics B Special Issue on "Neutrino Oscillations" celebrating the Nobel Prize in Physics 201

    Status of three-neutrino oscillation parameters, circa 2013

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    The standard three-neutrino (3nu) oscillation framework is being increasingly refined by results coming from different sets of experiments, using neutrinos from solar, atmospheric, accelerator and reactor sources. At present, each of the known oscillation parameters [the two squared mass gaps (delta m^2, Delta m^2) and the three mixing angles (theta_12}, theta_13, theta_23)] is dominantly determined by a single class of experiments. Conversely, the unknown parameters [the mass hierarchy, the theta_23 octant and the CP-violating phase delta] can be currently constrained only through a combined analysis of various (eventually all) classes of experiments. In the light of recent new results coming from reactor and accelerator experiments, and of their interplay with solar and atmospheric data, we update the estimated N-sigma ranges of the known 3nu parameters, and revisit the status of the unknown ones. Concerning the hierarchy, no significant difference emerges between normal and inverted mass ordering. A slight overall preference is found for theta_23 in the first octant and for nonzero CP violation with sin delta < 0; however, for both parameters, such preference exceeds 1 sigma only for normal hierarchy. We also discuss the correlations and stability of the oscillation parameters within different combinations of data sets.Comment: Updated and revised version, accepted for publication in PRD. The analysis includes the latest (March 2014) T2K disappearance data: all the figures and the numerical results have been updated, and parts of the text have been revised accordingl

    Thrombophilia and varicella zoster in children

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    From 2005 to 2011, 25 children of both sexes (13 boys and 12 girls, mean age 7.8 ± 2.5 years, 5-12.4 years) with acute varicella zoster virus (VZV) infection were selected. Five patients showed venous thromboembolism characterized by deep venous thrombosis (DVT). Comparison of activated partial thromboplastin time, antithrombin III, D-dimer, lupus anticoagulant, free S protein (PS), C protein, and antiphospholipid and PS antibodies was performed on children with acute VZV and DVT (group I), acute uncomplicated VZV (group II), and 30 healthy controls of both sexes (15 boys and 15 girls, mean age 7.5 ± 2.6 years, group III). Genetic thrombophilic mutations (Factor V Leiden, MTHFR C677T, and Prothrombin G20210A) were evaluated. Coagulation disorders and PS antibody were found in children with acute VZV (groups I and II). Significant differences were shown among the three groups (P0.05). Acute VZV infection could be associated with coagulation disorders and production of inhibitory PS antibodies in many uncomplicated cases

    Lateral stress evolution in chromium sulfide cermets with varying excess chromium

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    The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a onedimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium content

    Scale-independent roughness value of cell membranes studied by means of AFM technique

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    AbstractThe roughness of cell membrane is a very interesting indicator of cell's health state. Atomic Force Microscopy allows us to investigate the roughness of cell membrane in great detail, but the obtained roughness value is scale-dependent, i.e. it strongly depends on measurement parameters, as scanning area and step size. The scale-dependence of the roughness value can be reduced by means of data filtration techniques, that are not standardized at nanometric scale, especially as far as biological data are concerned. In this work, a new method, based on the changes of values of some roughness parameter (root mean square roughness and skewness) as a function of filtration frequencies, has been implemented to optimize data filtering procedure in the calculation of cell membrane roughness. In this way, a root mean square roughness value independent of cell shape, membrane micro-irregularities and measurement parameters can be obtained. Moreover, different filtration frequencies selected with this method allow us to discriminate different surface regimes (nominal form, waviness and roughness) belonging to the raw cell profile, each one related to different features of the cell surface

    Effect on haematological and anthropometric parameters of iron supplementation in the first 2 years of life. Risks and benefits

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    Effects of iron supplementation (IS) on haematological and anthropometric parameters in a cohort of 121 healthy children, followed from 6 to 24 months of life, in the Paediatric Department, Second University of Naples, were evaluated. Children were randomly segregated in four groups: (1) exclusively breast feeding (BF) weaned with non-iron fortified (NIF) foods, (2) BF and iron fortified formulas (IFF) and foods, (3) exclusively IFF and foods, (4) BF and oral iron supplementation (OIS). Haematological parameters (Hb, MCV, Serum ferritin and transferrin saturation) in addition to anthropometric measurements (length and weight) were obtained. Results from the study at 6, 12, 18 and 24 months showed significantly lower values of haematological parameters in BF infants than other groups and in IFF infants than in those with OIS. In contrast children with OIS showed significant lower length. It appears that IS may be of limited or no benefit for growth in non-iron deficient children

    Global fits to neutrino oscillations: status and prospects

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    In this work we review our present knowledge of the neutrino oscillation parameters. In a threeneutrino framework, neutrino oscillations depend on six parameters, two squared mass differences (Δm2,δm2), three mixing angles (θ12, θ13, θ23) and one phase δ. Five out of these six parameters have been measured by a number of experiments and only the CP-violating phase δ remains unknown. Moreover, the octant of the mixing angle θ23 and the neutrino mass hierarchy are still undetermined. We update our previous 2014 analysis, by adding to the global fit the recent results of the antineutrino running of T2K and the first results of the NOvA experiment
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