1,666 research outputs found

    12C emission from 114Ba and nuclear properties

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    We investigate the influence of nuclear masses, radii, and interaction potentials on 12C radioactivity of 114the best representative of a new island of cluster emitters leading to daughter nuclei around the doubly magic 100Sn. Three different models are considered: one derived by Blendowske, Fliessbach, and Walliser (BFW) from the many-body theory of alpha decay, as well as our analytical (ASAF) and numerical (NuSAF) superasymmetric fission models. A Q value larger by 1 MeV or an ASAF potential barrier reduced by 3% are producing a half-life shorter by 2 orders of magnitude. A similar effect can be obtained within BFW and NuSAF by a decrease of the action integral with less than 10% and 5%, respectively. By increasing the radius constant within ASAF or BFW models by 10%, the half-life becomes shorter by 3 orders of magnitude

    The Effect of Georgetown Steel Corp. v. United States on Nonmarket Economy Imports

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    Nanoengineered Curie Temperature in Laterally-Patterned Ferromagnetic Semiconductor Heterostructures

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    We demonstrate the manipulation of the Curie temperature of buried layers of the ferromagnetic semiconductor (Ga,Mn)As using nanolithography to enhance the effect of annealing. Patterning the GaAs-capped ferromagnetic layers into nanowires exposes free surfaces at the sidewalls of the patterned (Ga,Mn)As layers and thus allows the removal of Mn interstitials using annealing. This leads to an enhanced Curie temperature and reduced resistivity compared to unpatterned samples. For a fixed annealing time, the enhancement of the Curie temperature is larger for narrower nanowires.Comment: Submitted to Applied Physics Letters (minor corrections

    s-Process Nucleosynthesis in Advanced Burning Phases of Massive Stars

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    We present a detailed study of s-process nucleosynthesis in massive stars of solar-like initial composition and masses 15, 20,25, and 30 Msun. We update our previous results of s-process nucleosynthesis during the core He-burning of these stars and then focus on an analysis of the s-process under the physical conditions encountered during the shell-carbon burning. We show that the recent compilation of the Ne22(alpha,n)Mg25 rate leads to a remarkable reduction of the efficiency of the s-process during core He-burning. In particular, this rate leads to the lowest overproduction factor of Kr80 found to date during core He-burning in massive stars. The s-process yields resulting from shell carbon burning turn out to be very sensitive to the structural evolution of the carbon shell. This structure is influenced by the mass fraction of C12 attained at the end of core helium burning, which in turn is mainly determined by the C12(alpha,gamma)O16 reaction. The still present uncertainty in the rate for this reaction implies that the s-process in massive stars is also subject to this uncertainty. We identify some isotopes like Zn70 and Rb87 as the signatures of the s-process during shell carbon burning in massive stars. In determining the relative contribution of our s-only stellar yields to the solar abundances, we find it is important to take into account the neutron exposure of shell carbon burning. When we analyze our yields with a Salpeter Initial Mass Function, we find that massive stars contribute at least 40% to s-only nuclei with mass A 90, massive stars contribute on average ~7%, except for Gd152, Os187, and Hg198 which are ~14%, \~13%, and ~11%, respectively.Comment: 52 pages, 16 figures, accepted for publication in Ap

    Akt1 and -2 inhibition diminishes terminal differentiation and enhances central memory CD8(+) T-cell proliferation and survival

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    The authors thank Dr Esteban Celis and Dr Rhea-Beth Markowitz for reviewing the manuscript and for their valuable suggestions and also thank Dr Lei Huang for his suggestions.Peer reviewedPublisher PD

    Complete right- and left-sided thoracic ducts associated with aberrant left vertebral artery: unreported case with surgical implications

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    Anatomy is the keystone to an appropriate understanding of surgical and radiological sciences. Here the authors report on a rare case of complete right- and left-sided thoracic ducts (TDs) associated with aberrant left-vertebral artery (LVA) arising from the aortic arch. The TDs originated from right and left cisterna chyli and terminated separately close to the left venous angle. Superior to the aortic arch, the TDs showed different relationships to the LVA; the right TD was ventral, while the left was dorsal in position. This report is associated with other variations detailed below, and may have important implications in cervicothoracic surgery. (Folia Morphol 2018; 77, 1: 156–160)

    Classification system for Egyptian heritage buildings

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    To create a classification system for heritage buildings, it is essential to delve into the architectural components of the buildings following a specific procedure. First, the different objects’ properties (including their architectural style, geometric characteristics and ratio, condition, construction method, cultural value, material, color, reflectance characteristics) are identified. Second, creating a systematic framework that identifies the lifestyle of each element, stating the grouping principle of heritage elements and the design composition of tables that identifies the geometrical form, material and functional features whether insulation or load tolerance. This paper presents the challenges in creating a unified classification system for an Egyptian heritage palace built in 1896 with different architectural styles; i.e Rocco, Baroque, Islamic and even architectural customized elements with Royal slogan; through different historical periods, where multiple elements and sections were detached and attached to the place during its lifetime. The formulated classification system can be generalized in similar heritage buildings built in the same era

    Evolution of Massive Stars Up to the End of Central Oxygen Burning

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    We present a detailed study of the evolution of massive stars of masses 15, 20, 25 and 30 \msun assuming solar-like initial chemical composition. The stellar sequences were evolved through the advanced burning phases up to the end of core oxygen burning. We present a careful analysis of the physical characteristics of the stellar models. In particular, we investigate the effect of the still unsettled reaction 12^{12}C(α\alpha,γ\gamma)16^{16}O on the advanced evolution by using recent compilations of this rate. We find that this rate has a significant impact on the evolution not only during the core helium burning phase, but also during the late burning phases, especially the shell carbon-burning. We have also considered the effect of different treatment of convective instability based on the Ledoux criterion in regions of varying molecular weight gradient during the hydrogen and helium burning phases. We compare our results with other investigations whenever available. Finally, our present study constitutes the basis of analyzing the nucleosynthesis processes in massive stars. In particular we will present a detail analysis of the {\it s}-process in a forthcoming paper.Comment: 46 pages, 15 figures. To be published in ApJ vol 611, August 10, 200
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