456 research outputs found
Hartree-Fock-Bogoliubov Calculations in Coordinate Space: Neutron-Rich Sulfur, Zirconium, Cerium, and Samarium Isotopes
Using the Hartree-Fock-Bogoliubov (HFB) mean field theory in coordinate
space, we investigate ground state properties of the sulfur isotopes from the
line of stability up to the two-neutron dripline (). In particular,
we calculate two-neutron separation energies, quadrupole moments, and rms-radii
for protons and neutrons. Evidence for shape coexistence is found in the very
neutron-rich sulfur isotopes. We compare our calculations with results from
relativistic mean field theory and with available experimental data. We also
study the properties of neutron-rich zirconium (), cerium
(), and samarium () isotopes which exhibit very large
prolate quadrupole deformations.Comment: 7 pages, 6 figures, 2 tables submitted to Phys. Rev.
Behavior of shell-model configuration moments
An important input into reaction theory is the density of states or the level
density. Spectral distribution theory (also known as nuclear statistical
spectroscopy) characterizes the secular behavior of the density of states
through moments of the Hamiltonian. One particular approach is to partition the
model space into subspaces and find the moments in those subspaces; a
convenient choice of subspaces are spherical shell-model configurations. We
revisit these configuration moments and find, for complete
many-body spaces, the following behaviors: (a) the configuration width is
nearly constant for all configurations; (b) the configuration asymmetry or
third moment is strongly correlated with the configuration centroid; (c) the
configuration fourth moment, or excess is linearly related to the square to the
configuration asymmetry. Such universal behavior may allow for more efficient
modeling of the density of states in a shell-model framework.Comment: 12 pages, 8 figure
A class of quasi-sparse companion pencils
In this paper, we introduce a general class of quasi-sparse potential companion pencils for arbitrary square matrix polynomials over an arbitrary field, which extends the class introduced in [B. Eastman, I.-J. Kim, B. L. Shader, K.N. Vander Meulen, Companion matrix patterns. Linear Algebra Appl. 436 (2014) 255-272] for monic scalar polynomials. We provide a canonical form, up to permutation, for companion pencils in this class. We also relate these companion pencils with other relevant families of companion linearizations known so far. Finally, we determine the number of different sparse companion pencils in the class, up to permutation.This work has been partially supported by theMinisterio de Economía y Competitividad of Spain through grants MTM2015-68805-REDT and MTM2015-65798-P
Towards a FPGA-controlled deep phase modulation interferometer
Deep phase modulation interferometry was proposed as a method to enhance
homodyne interferometers to work over many fringes. In this scheme, a
sinusoidal phase modulation is applied in one arm while the demodulation takes
place as a post-processing step. In this contribution we report on the
development to implement this scheme in a fiber coupled interferometer
controlled by means of a FPGA, which includes a LEON3 soft-core processor. The
latter acts as a CPU and executes a custom made application to communicate with
a host PC. In contrast to usual FPGA-based designs, this implementation allows
a real-time fine tuning of the parameters involved in the setup, from the
control to the post-processing parameters.Comment: Proceedings of the X LISA Symposium, Gainesville, May 18-23, 201
Highly viscoelastic films at the water/air interface: α-Cyclodextrin with anionic surfactants
This work showcases the remarkable viscoelasticity of films consisting of α-cyclodextrin (α-CD) and anionic surfactants (S) at the water/air interface, the magnitude of which has not been observed in similar systems. The anionic surfactants employed are sodium salts of a homologous series of n-alkylsulfates (n = 8–14) and of dodecylsulfonate. Our hypothesis was that the very high viscoelasticity can be systematically related to the bulk and interfacial properties of the system. Through resolution of the bulk distribution of species using isothermal titration calorimetry, the high dilatational modulus is related to (α-CD)2:S1 inclusion complexes in the bulk with respect to both the bulk composition and temperature. Direct interfacial characterization of α-CD and sodium dodecylsulfate films at 283.15 K using ellipsometry and neutron reflectometry reveals that the most viscoelastic films consist of a highly ordered monolayer of 2:1 complexes with a minimum amount of any other component. The orientation of the complexes in the films and their driving force for adsorption are discussed in the context of results from molecular dynamics simulations. These findings open up clear potential for the design of new functional materials or molecular sensors based on films with specific mechanical, electrical, thermal, chemical, optical or even magnetic properties
Carbono de biomasa microbiana y nitrógeno potencialmente mineralizable sobre sistemas conservacionistas en la región chaqueña
Hydrophilic and lipophilic radiopharmaceuticals as tracers in pharmaceutical development: In vitro – In vivo studies
BACKGROUND: Scintigraphic studies have been performed to assess the release, both in vitro and in vivo, of radiotracers from tablet formulations. Four different tracers with differing physicochemical characteristics have been evaluated to assess their suitability as models for drug delivery. METHODS: In-vitro disintegration and dissolution studies have been performed at pH 1, 4 and 7. In-vivo studies have been performed by scintigraphic imaging in healthy volunteers. Two hydrophilic tracers, ((99m)Tc-DTPA) and ((99m)Tc-MDP), and two lipophilic tracers, ((99m)Tc-ECD) and ((99m)Tc-MIBI), were used as drug models. RESULTS: Dissolution and disintegration profiles, differed depending on the drug model chosen. In vitro dissolution velocity constants indicated a probable retention of the radiotracer in the formulation. In vivo disintegration velocity constants showed important variability for each radiopharmaceutical. Pearson statistical test showed no correlation between in vitro drug release, and in vivo behaviour, for (99m)Tc-DTPA, (99m)Tc-ECD and (99m)Tc-MIBI. High correlation coefficients were found for (99m)Tc-MDP not only for in vitro dissolution and disintegration studies but also for in vivo scintigraphic studies. CONCLUSION: Scintigraphic studies have made a significant contribution to the development of drug delivery systems. It is essential, however, to choose the appropriate radiotracers as models of drug behaviour. This study has demonstrated significant differences in release patterns, depending on the model chosen. It is likely that each formulation would require the development of a specific model, rather than being able to use a generic drug model on the basis of its physicochemical characteristics
Axially symmetric Hartree-Fock-Bogoliubov Calculations for Nuclei Near the Drip-Lines
Nuclei far from stability are studied by solving the Hartree-Fock-Bogoliubov
(HFB) equations, which describe the self-consistent mean field theory with
pairing interaction. Calculations for even-even nuclei are carried out on
two-dimensional axially symmetric lattice, in coordinate space. The
quasiparticle continuum wavefunctions are considered for energies up to 60 MeV.
Nuclei near the drip lines have a strong coupling between weakly bound states
and the particle continuum. This method gives a proper description of the
ground state properties of such nuclei. High accuracy is achieved by
representing the operators and wavefunctions using the technique of
basis-splines. The detailed representation of the HFB equations in cylindrical
coordinates is discussed. Calculations of observables for nuclei near the
neutron drip line are presented to demonstrate the reliability of the method.Comment: 13 pages, 4 figures. Submitted to Physical Review C on 05/08/02.
Revised on Dec/0
Indicadores de maturação para definição de ponto de colheita do maracujá selvagem (passiflora tenuifila) cultivado na região de cerrado.
O Maracujá-selvagem é uma das espécies depositadas no BAG de Passifloras da Embrapa Cerrados que estão sendo estudadas para fins de melhoramento genético. Neste trabalho buscou-se avaliar uma metodologia de campo, para definição do ponto de colheita do fruto tomando-se como referência indicadores físicos, físico-químicos e de aparência dos frutos em 7 (sete) estádios. Fez-se comparações entre índices de aparência do fruto com as variáveis massa total,da casca, da polpa, das sementes e seus respectivos percentuais em relação ao fruto total, o diâmetro transversal e longitudinal e teor de açucares solúveis totais na polpa. Os resultados indicaram que o ponto ótimo de colheita dos frutos dá-se no estádio 3, quando apresentam aparência com coloração amarela em até 20% da casca e valores médios de 18,45g de massa total. Na polpa 26,5o Brix de açucares solúveis totais, 0,82% de acidez total titulável e pH 4,43
Technical Efficiency of Dairy Farms in Sierra Andina Using Neural Network Modeling
The aim of this paper was to estimate the efficiency of milk production of 1 168 cases in Ecuadoran Sierra Sur Andina, with the implementation of a neural network model with multilayer perceptrons. These cases were collected from secondary samples provided by the Official Institute of National Statistics of Ecuador, in 2016. The variables chosen for the model were total milk production on the previous day (P), as dependent variable, and total cattle heads (CH), total laborers in the field (E), and total area attended by laborer (S), as independent variables. The data from individual cases and their impact on the dependent variable were used as the variable selection criteria. The average efficiency was 8.11%, from which the total efficient cases detected (>0.70) were 11 (0.9% of the sample). Later, the cases studied were classified into three groups, depending on the estimated efficiency: Group 1 (≤ 0.4 efficiency); Group 2 (>0.4-≤0.7 efficiency); and Group 3 (>0.7 efficiency). A comparison produced several statistical differences (P<0.01) for variables total milk production/year on the farm, total field laborers, farm size, total cows, total cattle heads, calvings, pregnant cows, and served cows.The aim of this paper was to estimate the efficiency of milk production of 1 168 cases in Ecuadoran Sierra Sur Andina, with the implementation of a neural network model with multilayer perceptrons. These cases were collected from secondary samples provided by the Official Institute of National Statistics of Ecuador, in 2016. The variables chosen for the model were total milk production on the previous day (P), as dependent variable, and total cattle heads (CH), total laborers in the field (E), and total area attended by laborer (S), as independent variables. The data from individual cases and their impact on the dependent variable were used as the variable selection criteria. The average efficiency was 8.11%, from which the total efficient cases detected (>0.70) were 11 (0.9% of the sample). Later, the cases studied were classified into three groups, depending on the estimated efficiency: Group 1 (≤ 0.4 efficiency); Group 2 (>0.4-≤0.7 efficiency); and Group 3 (>0.7 efficiency). A comparison produced several statistical differences (P<0.01) for variables total milk production/year on the farm, total field laborers, farm size, total cows, total cattle heads, calvings, pregnant cows, and served cows
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