662 research outputs found

    A Symmetry Adapted Approach to Molecular Spectroscopy: The Anharmonic Oscillator Symmetry Model

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    We apply the Anharmonic Oscillator Symmetry Model to the description of vibrational excitations in D3h{\cal D}_{3h} and Td{\cal T}_d molecules. A systematic procedure can be used to establish the relation between the algebraic and configuration space formulations, by means of which new interactions are found in the algebraic model, leading to reliable spectroscopic predictions. We illustrate the method for the case of D3h{\cal D}_{3h}-triatomic molecules and the Td{\cal T}_d Be-cluster.Comment: 12 pages, invited talk at XIX Oaxtepec Symposium on Nuclear Physics, January 199

    Quality of Life in Spanish Patients with Liver Transplant

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    Background: Liver transplantation is the optimal method of treatment in patients with end-stage liver failure. Transplantation medicine has significantly progressed in the last time, but some psychology and psychosomatic problems still remain unsolved. Health-Related Quality of Life (HRQL) in liver transplant is considered a useful measure of evolutionary process of the illness. Objective: The authors analyzed the evolution of HRQL in pre-transplant (waiting-list patients) and post-transplant (first year after liver transplant) periods of liver transplant Spanish patients. Methods: A prospective and longitudinal study was carried out among patients who received a liver transplant from a deceased donor. They were assessed in four phases: at the time of inclusion on the transplant waiting-list, and 3, 6, and 12 months after receiving the graft. We used a structured interview and SF-36 and Euroqol-5D (EQ-5D) Health Questionnaires. Results: The greater differences were found between pre-transplant and post-transplant stages with less well-being in the stage before the transplant. No significantly differences were observed when comparing the 3, 6 and 12 months from posttransplant stage. Conclusion: The HQRL of liver patients improved after the transplant, being appreciated a tendency to the stabilization from three months onwards. We suggest that the psychological intervention, in liver patients, should be conducted in waiting- list patients and in the first 3 months post-transplant, periods with a poor mental health (anxiety, depression, and stress by fear to the unknown thing) and a low adhesion to the treatment that can generate a smaller graft and/or patient survival.Transplant Research Network RETIC FIS C03/03Junta de Andalucí

    Decay study of pesticide residues in apple samples

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    A method for monitoring pesticides in apple samples, including Soxhlet extraction, an evaporation step and capillary gas chromatography with nitrogen-phosphorus detection, is applied to a decay study of the carbamate pesticide ethiofencarb. The evaporation step is carried out by a surface nitrogen flow and the recoveries of ethiofencarb measured in standard solutions of ethyl acetate and apple extracts. The results of the decay studies show that ethiofencarb is degraded in the apple peel faster than in the interior of the fruit. The methodology is then applied to decay studies in the laboratory of the organophosphorus pesticides, diclofluanid, fenitrothion and malathion

    Threading Through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers

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    In this work we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine single-walled carbon nanotubes (SWNTs), mechanically interlocked derivatives of SWNTs (MINTs) and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200 % were observed for the polystyrene-MINTs samples with an optimized loading of just 0.01 wt.%, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence. This behavior is found for three different types of SWNTs and two types of macrocycles. Molecular dynamics simulations show that the polymer adopts an elongated conformation parallel to the SWNT when interacting with MINT fillers, irrespective of the macrocycle chemical nature, whereas a more globular structure is taken upon facing with either pristine SWNTs or supramolecular models. The MINT composite architecture thus leads to a more efficient exploitation of the axial properties of the SWNTs and of the polymer chain at the interface, in agreement with experimental results. Our findings demonstrate that the mechanical bond imparts distinctive advantageous properties to SWNT derivatives as polymer fillers.Comment: 39 pages, 19 figure

    Excited-state quantum phase transitions in the anharmonic Lipkin-Meshkov-Glick model: Static aspects

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    The basic Lipkin-Meshkov-Glick model displays a second-order ground-state quantum phase transition and an excited-state quantum phase transition (ESQPT). The inclusion of an anharmonic term in the Hamiltonian implies a second ESQPT of a different nature. We characterize this ESQPT using the mean field limit of the model. The alternative ESQPT, associated with the changes in the boundary of the finite Hilbert space of the system, can be properly described using the order parameter of the ground-state quantum phase transition, the energy gap between adjacent states, the participation ratio, and the quantum fidelity susceptibility.I + D + i Projects - MCIN/AEI PID2019-104002GB-C21 PID2019104002GB-C22 PID2020-114687GB-I00 MCIN/AEI/10.13039/501100011033Junta de AndaluciaEuropean Commission UHU-1262561 US-1380840Junta de Andalucia P20_01247ERDF-A Way of Making Europe European CommissionSpanish Government UNHU-15CE-2848European Union NextGenerationEU/PRT

    Four-body continuum-discretized coupled-channels calculations using a transformed harmonic oscillator basis

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    The scattering of a weakly bound three-body system by a target is discussed. A transformed harmonic oscillator basis is used to provide an appropriate discrete and finite basis for treating the continuum part of the spectrum of the projectile. The continuum-discretized coupled channels framework is used for the scattering calculations. The formalism is applied to different reactions, 6He+12C at 229.8 MeV, 6He+64Zn at 10 and 13.6 MeV, and 6He+208Pb at 22 MeV, induced by the Borromean nucleus 6He. Both the Coulomb and nuclear interactions with a target are taken into account.Comment: Published in Phys. Rev.

    Estimation of the Primary Net Production above Ground through Remote Sensing in a Pastoral System of the Colombian Altillanura.

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    The primary net production above ground (ANPP) represents the main forage resource that supports the bovine production systems and its valuation is essential to help in the decision making on the management of the pastures. The ANPP has been estimated by periodic biomass courtesy, but with the use of the remote sensor integrated into the efficiency model formulated by Monteih (1972), it has been possible to estimate this biophysical parameter more efficiently at different scales and at low cost. The objective of this study was to estimate the PPNA based on a model of efficiency in the use of light for pastoral coverage in the Colombian Altillanura. The work is in the Carimagua Research Center of the Colombian Agricultural Research Corporation –AGROSAVIA– located in the municipality of Puerto Gaitán - Meta, Colombia. The pasture was monitored through forage supply gaps, in 14 paddocks with an approximate area of 2.6 ha each, established with Urochloa humidicola CIAT 6133 c.v Llanero under grazing of cattle with rest periods of 28 to 30 days. The spectral information was obtained from the on-board Sentinel 2 sensor and the global radiation data was obtained from a field weather station. A PPNA observed in the field and estimated by the efficiency model of 603.79 ±189kgDM/ha ± 188 and de 589.22 ±104 kgDM/ha was found, with a coefficient of determination R2 (0.79) and a significant correlation p \u3c 0.01 of 0.89. This methodology would quantify the supply of fodder on a larger scale under the same type of pastures

    Physical Education Classes as a Precursor to the Mediterranean Diet and the Practice of Physical Activity

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    Physical activity and a healthy, balanced diet are remaining unresolved issues among young people. According to the World Health Organization, young people do not get enough exercise during the week, and physical education classes are the best way to promote healthy habits. This study aims to analyze how the role of the teacher influences the frustration of psychological needs, coping strategies, motivation, and the adoption of healthy eating habits through the Mediterranean diet and the regular practice of physical activity. The study involved 1031 boys and 910 girls between the ages of 13 and 18. To explain the relationships between the different variables included in this study, a model of structural equations has been developed. The results showed that autonomy support negatively predicted the frustration of four psychological needs. The failure to meet four psychological needs negatively predicted resilience. Likewise, resilience positively predicted autonomous motivation, and this positively predicted the Mediterranean diet and the practice of physical activity. Thus, the results obtained in the present study are in line with those of various studies wherein physical education classes were seen to help consolidate healthy living habits

    Three-body continuum discretization in a basis of transformed harmonic oscillator states

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    The inclusion of the continuum in the study of weakly-bound three-body systems is discussed. A transformed harmonic oscillator basis is introduced to provide an appropriate discrete and finite basis for treating the continuum part of the spectrum. As examples of the application of the method the strength functions corresponding to several operators that couple the ground state to the continuum are investigated, for 6He, and compared with previous calculations. It is found that the energy moments of these distributions are accurately reproduced with a small basis set.Comment: 12 figures, submitted to PR
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