8,489 research outputs found

    Examining the Overlapping Traits of Athletes and Entrepreneurs Through a Series of Case Studies

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    Today’s psychologists have paid close attention to personality and how it can affect many areas of a person’s life. From career success to criminal behavior psychologists continuously are trying to define key characteristics that may be contributing factors in the prediction of future happenings. This paper will look closely at theories regarding personality traits that are key to success. Those traits are identified in eight case studies relating to both entrepreneurial and athletic success with the findings showing a possible link between success and some key traits and an overlap of some traits between athletes and entrepreneurs

    Combining real and virtual Higgs boson mass constraints

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    Within the framework of the standard model we observe that there is a significant discrepancy between the most precise ZZ boson decay asymmetry measurement and the limit from direct searches for Higgs boson production. Using methods inspired by the Particle Data Group we explore the possible effect on fits of the Higgs boson mass. In each case the central value and the 95% confidence level upper limit increase significantly relative to the conventional fit. The results suggest caution in drawing conclusions about the Higgs boson mass from the existing data.Comment: 11 pages, Latex. Citations are added and paper is otherwise reconciled with version to be published in Physical Review Letter

    Search for Associations Containing Young stars (SACY): Chemical tagging IC 2391 & the Argus association

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    We explore the possible connection between the open cluster IC 2391 and the unbound Argus association identified by the SACY survey. In addition to common kinematics and ages between these two systems, here we explore their chemical abundance patterns to confirm if the two substructures shared a common origin. We carry out a homogenous high-resolution elemental abundance study of eight confirmed members of IC 2391 as well as six members of the Argus association using UVES spectra. We derive spectroscopic stellar parameters and abundances for Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni and Ba. All stars in the open cluster and Argus association were found to share similar abundances with the scatter well within the uncertainties, where [Fe/H] = -0.04 +/-0.03 for cluster stars and [Fe/H] = -0.06 +/-0.05 for Argus stars. Effects of over-ionisation/excitation were seen for stars cooler than roughly 5200K as previously noted in the literature. Also, enhanced Ba abundances of around 0.6 dex were observed in both systems. The common ages, kinematics and chemical abundances strongly support that the Argus association stars originated from the open cluster IC 2391. Simple modeling of this system find this dissolution to be consistent with two-body interactions.Comment: 17 pages, 7 figs, accepted for publication in MNRA

    Some Dynamical Effects of the Cosmological Constant

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    Newton's law gets modified in the presence of a cosmological constant by a small repulsive term (antigarvity) that is proportional to the distance. Assuming a value of the cosmological constant consistent with the recent SnIa data (Λ1052m2\Lambda \simeq 10^{-52} m^{-2}) we investigate the significance of this term on various astrophysical scales. We find that on galactic scales or smaller (less than a few tens of kpc) the dynamical effects of the vacuum energy are negligible by several orders of magnitude. On scales of 1Mpc or larger however we find that vacuum energy can significantly affect the dynamics. For example we show that the velocity data in the Local Group of galaxies correspond to galactic masses increased by 35% in the presence of vacuum energy. The effect is even more important on larger low density systems like clusters of galaxies or superclusters.Comment: 5 two column pages, 2 figure

    Concepts, Developments and Advanced Applications of the PAX Toolkit

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    The Physics Analysis eXpert (PAX) is an open source toolkit for high energy physics analysis. The C++ class collection provided by PAX is deployed in a number of analyses with complex event topologies at Tevatron and LHC. In this article, we summarize basic concepts and class structure of the PAX kernel. We report about the most recent developments of the kernel and introduce two new PAX accessories. The PaxFactory, that provides a class collection to facilitate event hypothesis evolution, and VisualPax, a Graphical User Interface for PAX objects

    Search for associations containing young stars (SACY). V. Is multiplicity universal? Tight multiple systems

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    Context: Dynamically undisrupted, young populations of stars are crucial to study the role of multiplicity in relation to star formation. Loose nearby associations provide us with a great sample of close (<<150 pc) Pre-Main Sequence (PMS) stars across the very important age range (\approx5-70 Myr) to conduct such research. Aims: We characterize the short period multiplicity fraction of the SACY (Search for Associations Containing Young stars) accounting for any identifiable bias in our techniques and present the role of multiplicity fractions of the SACY sample in the context of star formation. Methods: Using the cross-correlation technique we identified double-lined spectroscopic systems (SB2), in addition to this we computed Radial Velocity (RV) values for our subsample of SACY targets using several epochs of FEROS and UVES data. These values were used to revise the membership of each association then combined with archival data to determine significant RV variations across different data epochs characteristic of multiplicity; single-lined multiple systems (SB1). Results: We identified 7 new multiple systems (SB1s: 5, SB2s: 2). We find no significant difference between the short period multiplicity fraction (FmF_\mathrm{m}) of the SACY sample and that of nearby star forming regions (\approx1-2 Myr) and the field (FmF_\mathrm{m}\leq10%) both as a function of age and as a function of primary mass, M1M_1, in the ranges PP [1:200 day] and M2M_2 [0.08 MM_{\odot}-M1 M_1]. Conclusions: Our results are consistent with the picture of universal star formation, when compared to the field and nearby star forming regions (SFRs). We comment on the implications of the relationship between increasing multiplicity fraction with primary mass, within the close companion range, in relation to star formation.Comment: 14 pages, 18 figures, published, A&A http://dx.doi.org/10.1051/0004-6361/20142385

    Calculation of isotope shifts and relativistic shifts in CI, CII, CIII and CIV

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    We present an accurate ab initio method of calculating isotope shifts and relativistic shifts in atomic spectra. We test the method on neutral carbon and three carbon ions. The relativistic shift of carbon lines may allow them to be included in analyses of quasar absorption spectra that seek to measure possible variations in the fine structure constant, alpha, over the lifetime of the Universe. Carbon isotope shifts can be used to measure isotope abundances in gas clouds: isotope abundances are potentially an important source of systematic error in the alpha-variation studies. These abundances are also needed to study nuclear reactions in stars and supernovae, and test models of chemical evolution of the Universe

    Nuclear timescale mass transfer in models of supergiant and ultra-luminous X-ray binaries

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    We investigate how the proximity of supergiant donor stars to the Eddington-limit, and their advanced evolutionary stage, may influence the evolution of massive and ultra-luminous X-ray binaries with supergiant donor stars (SGXBs and ULXs). We construct models of massive stars with different internal hydrogen/helium gradients and different hydrogen-rich envelope masses, and expose them to slow mass loss to probe the response of the stellar radius. In addition, we compute the corresponding Roche-lobe overflow mass-transfer evolution with our detailed binary stellar evolution code, approximating the compact objects as point masses. We find that a hydrogen/helium gradient in the layers beneath the surface, as it is likely present in the well-studied donor stars of observed SGBXs, can enable nuclear timescale mass-transfer in SGXBs with a BH or a NS accretor, even for mass ratios in excess of 20. In our binary evolution models, the donor stars rapidly decrease their thermal equilibrium radius and can therefore cope with the inevitably strong orbital contraction imposed by the high mass ratio. Our results open a new perspective for understanding the large number of Galactic SGXBs, and their almost complete absence in the SMC. They may also offer a way to obtain more ULX systems, to find nuclear timescale mass-transfer in ULX systems even with neutron star accretors, and shed new light on the origin of the strong B-field in these neutron stars.Comment: 23 pages, 21 figures, we are thankful for any comments an this draf

    Varying Alpha Monopoles

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    We study static magnetic monopoles in the context of varying alpha theories and show that there is a group of models for which the t'Hooft-Polyakov solution is still valid. Nevertheless, in general static magnetic monopole solutions in varying alpha theories depart from the classical t'Hooft-Polyakov solution with the electromagnetic energy concentrated inside the core seeding spatial variations of the fine structure constant. We show that Equivalence Principle constraints impose tight limits on the allowed variations of alpha induced by magnetic monopoles which confirms the difficulty to generate significant large-scale spatial variation of the fine structure constant found in previous works. This is true even in the most favorable case where magnetic monopoles are the source for these variations.Comment: 8 pages, 10 figures; Version to be published in Phys. Rev.

    The alpha-dependence of transition frequencies for some ions of Ti, Mn, Na, C, and O, and the search for variation of the fine structure constant

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    We use the relativistic Hartree-Fock method, many-body perturbation theory and configuration-interaction method to calculate the dependence of atomic transition frequencies on the fine structure constant, alpha. The results of these calculations will be used in the search for variation of the fine structure constant in quasar absorption spectra.Comment: 4 pages, 5 table
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