1,260 research outputs found

    The hydrogenation of metals upon interaction with water

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    Hydrogen evolution at 600 deg and 5 x 10 to the 7th power - 10 to the 6th power torr from AVOOO Al samples, which were pickled in 10 percent NaOH, is discussed. An H evolution kinetic equation is derived for samples of equal vol. and different surfaces (5 and 20 sq cm). The values of the H evolution coefficient K indicated an agreement with considered H diffusion mechanism through an oxide layer. The activation energy for the H evolution process, obtained from the K-temp. relation, was 13,000 2000 cal/g-atom

    Abrupt changes in alpha decay systematics as a manifestation of collective nuclear modes

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    An abrupt change in α\alpha decay systematics around the N=126 neutron shell closure is discussed. It is explained as a sudden hindrance of the clustering of the nucleons that eventually form the α\alpha particle. This is because the clustering induced by the pairing mode acting upon the four nucleons is inhibited if the configuration space does not allow a proper manifestation of the pairing collectivity.Comment: 6 pages, 3 figures, submitted to Phys. Rev. C, a few new references adde

    On one Approach for Stable Estimate of Technical System Efficiency

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    In present paper the problem of efficiency evaluation of technical system by measurable structural design parameters is investigated. To accomplish the purpose of considered problem it is constructed the mathematical model in the form of a finite-dimensional operator equation, where desired elements are both influence weights of the calculated structural design parameters and technical effectiveness indicator of the system. First, the constructed model is reduced to the normal system, and then the apparatus of the ill-posed inverse problem theory is used for the reduced problem: a regularizing operator is constructed and an algorithm for finding the regularization parameter is developed.

    The detection of patients at risk of gastrointestinal toxicity during pelvic radiotherapy by electronic nose and FAIMS : a pilot study

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    It is well known that the electronic nose can be used to identify differences between human health and disease for a range of disorders. We present a pilot study to investigate if the electronic nose and a newer technology, FAIMS (Field Asymmetric Ion Mobility Spectrometry), can be used to identify and help inform the treatment pathway for patients receiving pelvic radiotherapy, which frequently causes gastrointestinal side-effects, severe in some. From a larger group, 23 radiotherapy patients were selected where half had the highest levels of toxicity and the others the lowest. Stool samples were obtained before and four weeks after radiotherapy and the volatiles and gases emitted analysed by both methods; these chemicals are products of fermentation caused by gut microflora. Principal component analysis of the electronic nose data and wavelet transform followed by Fisher discriminant analysis of FAIMS data indicated that it was possible to separate patients after treatment by their toxicity levels. More interestingly, differences were also identified in their pre-treatment samples. We believe these patterns arise from differences in gut microflora where some combinations of bacteria result to give this olfactory signature. In the future our approach may result in a technique that will help identify patients at “high risk” even before radiation treatment is started

    Structural evolution in Pt isotopes with the Interacting Boson Model Hamiltonian derived from the Gogny Energy Density Functional

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    Spectroscopic calculations are carried out, for the description of the shape/phase transition in Pt nuclei in terms of the Interacting Boson Model (IBM) Hamiltonian derived from (constrained) Hartree-Fock-Bogoliubov (HFB) calculations with the finite range and density dependent Gogny-D1S Energy Density Functional. Assuming that the many-nucleon driven dynamics of nuclear surface deformation can be simulated by effective bosonic degrees of freedom, the Gogny-D1S potential energy surface (PES) with quadrupole degrees of freedom is mapped onto the corresponding PES of the IBM. Using this mapping procedure, the parameters of the IBM Hamiltonian, relevant to the low-lying quadrupole collective states, are derived as functions of the number of valence nucleons. Merits of both Gogny-HFB and IBM approaches are utilized so that the spectra and the wave functions in the laboratory system are calculated precisely. The experimental low-lying spectra of both ground-state and side-band levels are well reproduced. From the systematics of the calculated spectra and the reduced E2 transition probabilities BB(E2), the prolate-to-oblate shape/phase transition is shown to take place quite smoothly as a function of neutron number NN in the considered Pt isotopic chain, for which the Îł\gamma-softness plays an essential role. All these spectroscopic observables behave consistently with the relevant PESs and the derived parameters of the IBM Hamiltonian as functions of NN. Spectroscopic predictions are also made for those nuclei which do not have enough experimental E2 data.Comment: 11 pages, 5 figure

    The views and practice of oncologists towards nutritional support in patients receiving chemotherapy

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    Malnutrition in patients with cancer is common and an adverse prognostic indicator. A questionnaire answered by 357 (72%) UK specialist oncological trainees suggests that they lack the ability to identify factors that place patients at risk from malnutrition. Major barriers to effective nutritional practice included lack of guidelines, knowledge and time

    Shape of primary proton spectrum in multi-TeV region from data on vertical muon flux

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    It is shown, that primary proton spectrum, reconstructed from sea-level and underground data on muon spectrum with the use of QGSJET 01, QGSJET II, NEXUS 3.97 and SIBYLL 2.1 interaction models, demonstrates not only model-dependent intensity, but also model-dependent form. For correct reproduction of muon spectrum shape primary proton flux should have non-constant power index for all considered models, except SIBYLL 2.1, with break at energies around 10-15 TeV and value of exponent before break close to that obtained in ATIC-2 experiment. To validate presence of this break understanding of inclusive spectra behavior in fragmentation region in p-air collisions should be improved, but we show, that it is impossible to do on the basis of the existing experimental data on primary nuclei, atmospheric muon and hadron fluxes.Comment: Submitted to Phys. Rev.
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