14,841 research outputs found

    Global superscaling analysis of quasielastic electron scattering with relativistic effective mass

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    We present a global analysis of the inclusive quasielastic electron scattering data with a superscaling approach with relativistic effective mass. The SuSAM* model exploits the approximation of factorization of the scaling function f∗(ψ∗)f^*(\psi^*) out of the cross section under quasifree conditions. Our approach is based on the relativistic mean field theory of nuclear matter where a relativistic effective mass for the nucleon encodes the dynamics of nucleons moving in presence of scalar and vector potentials. Both the scaling variable ψ∗\psi^* and the single nucleon cross sections include the effective mass as a parameter to be fitted to the data alongside the Fermi momentum kFk_F. Several methods to extract the scaling function and its uncertainty from the data are proposed and compared. The model predictions for the quasielastic cross section and the theoretical error bands are presented and discussed for nuclei along the periodic table from A=2A=2 to A=238A=238: 2^2H, 3^3H, 3^3He, 4^4He, 12^{12}C, 6^{6}Li, 9^{9}Be, 24^{24}Mg, 59^{59}Ni, 89^{89}Y, 119^{119}Sn, 181^{181}Ta, 186^{186}W, 197^{197}Au, 16^{16}O, 27^{27}Al, 40^{40}Ca, 48^{48}Ca, 56^{56}Fe, 208^{208}Pb, and 238^{238}U. We find that more than 9000 of the total ∼20000\sim 20000 data fall within the quasielastic theoretical bands. Predictions for 48^{48}Ti and 40^{40}Ar are also provided for the kinematics of interest to neutrino experiments.Comment: 26 pages, 20 figures and 4 table

    Analysis of CMB maps with 2D wavelets

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    We consider the 2D wavelet transform with two scales to study sky maps of temperature anisotropies in the cosmic microwave background radiation (CMB). We apply this technique to simulated maps of small sky patches of size 12.8 \times 12.8 square degrees and 1.5' \times 1.5' pixels. The relation to the standard approach, based on the cl's is established through the introduction of the scalogram. We consider temperature fluctuations derived from standard, open and flat-Lambda CDM models. We analyze CMB anisotropies maps plus uncorrelated Gaussian noise (uniform and non-uniform) at idfferent S/N levels. We explore in detail the denoising of such maps and compare the results with other techniques already proposed in the literature. Wavelet methods provide a good reconstruction of the image and power spectrum. Moreover, they are faster than previously proposed methods.Comment: latex file 7 pages + 5 postscript files + 1 gif file; accepted for publication in A&A

    Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

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    We propose a unique program of measurements of electric and magnetic dipole moments of charm, beauty and strange charged baryons at the LHC, based on the phenomenon of spin precession of channeled particles in bent crystals. Studies of crystal channeling and spin precession of positively- and negatively-charged particles are presented, along with feasibility studies and expected sensitivities for the proposed experiment using a layout based on the LHCb detector.Comment: 19 pages, 13 figure

    Compact groups from semi-analytical models of galaxy formation -- V: their assembly channels as a function of the environment

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    We delved into the assembly pathways and environments of compact groups (CGs) of galaxies using mock catalogues generated from semi-analytical models (SAMs) on the Millennium simulation. We investigate the ability of SAMs to replicate the observed CG environments and whether CGs with different assembly histories tend to inhabit specific cosmic environments. We also analyse whether the environment or the assembly history is more important in tailoring CG properties. We find that about half of the CGs in SAMs are non-embedded systems, 40% are inhabiting loose groups or nodes of filaments, while the rest distribute evenly in filaments and voids, in agreement with observations. We observe that early-assembled CGs preferentially inhabit large galaxy systems (~ 60%), while around 30% remain non-embedded. Conversely, lately-formed CGs exhibit the opposite trend. We also obtain that lately-formed CGs have lower velocity dispersions and larger crossing times than early-formed CGs, but mainly because they are preferentially non-embedded. Those lately-formed CGs that inhabit large systems do not show the same features. Therefore, the environment plays a strong role in these properties for lately-formed CGs. Early-formed CGs are more evolved, displaying larger velocity dispersions, shorter crossing times, and more dominant first-ranked galaxies, regardless of the environment. Finally, the difference in brightness between the two brightest members of CGs is dependent only on the assembly history and not on the environment. CGs residing in diverse environments have undergone varied assembly processes, making them suitable for studying their evolution and the interplay of nature and nurture on their traits.Comment: 13 pages, 8 figures. Accepted for publication in MNRA

    Semiempirical formula for two-nucleon emission induced by short-range correlations in electron and neutrino scattering

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    A semiempirical formula is proposed for the emission cross section of two correlated nucleons. We assume that the two-particle emission response is proportional to the two-particle two-hole phase space multiplied by an averaged single-nucleon response. The effect of the short-range correlations is encoded in a correlation coefficient that is linked to an average of the high-momentum distribution of a nucleon pair. The correlation coefficient depends only on the momentum transfer and is obtained from a fit to the tail of the phenomenological scaling function. We present predictions for the inclusive two-nucleon emission cross section induced by electrons and neutrinos including short-range correlations and meson-exchange currents.Comment: 14 pages, 8 figures. Major revision, with 5 more pages, a new section, an appendix and a figur

    Interaction between a Novel Oligopeptide Fragment of the Human Neurotrophin Receptor TrkB Ectodomain D5 and the C-Terminal Fragment of Tetanus Neurotoxin

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    This article presents experimental evidence and computed molecular models of a potential interaction between receptor domain D5 of TrkB with the carboxyl-terminal domain of tetanus neurotoxin (Hc-TeNT). Computational simulations of a novel small cyclic oligopeptide are designed, synthesized, and tested for possible tetanus neurotoxin-D5 interaction. A hot spot of this protein-protein interaction is identified in analogy to the hitherto known crystal structures of the complex between neurotrophin and D5. Hc-TeNT activates the neurotrophin receptors, as well as its downstream signaling pathways, inducing neuroprotection in different stress cellular models. Based on these premises, we propose the Trk receptor family as potential proteic affinity receptors for TeNT. In vitro, Hc-TeNT binds to a synthetic TrkB-derived peptide and acts similar to an agonist ligand for TrkB, resulting in phosphorylation of the receptor. These properties are weakened by the mutagenesis of three residues of the predicted interaction region in Hc-TeNT. It also competes with Brain-derived neurotrophic factor, a native binder to human TrkB, for the binding to neural membranes, and for uptake in TrkB-positive vesicles. In addition, both molecules are located together in vivo at neuromuscular junctions and in motor neurons

    Managerial and leadership effectiveness as perceived by managers and non-managerial employees in Mexico

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    Using the critical incident (CI) technique, concrete examples of effective and ineffective managerial behaviour (CIs) were collected from managers and non-managerial employees within private and public sector organizations situated in the north and southeast regions of Mexico. The CIs were content analysed using open, axial and selective coding to identify a smaller number of thematic categories. A total of 38 ‘manager’ and 35 ‘non-managerial employee’ behavioural categories were identified respectively, of which 82.19% (n = 60) were found to be either convergent or polar opposite in meaning. The findings suggest that what behaviourally differentiates effective managers from ineffective managers is perceived, described and defined by Mexican managers and non-managerial employees in much the same way. The study provides new insights on the issue of perceived managerial and leadership effectiveness in Mexico and is a rare example of indigenous managerial behaviour research in a non-Anglo country
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