660 research outputs found
Solutions of the dispersion equation in the region of overlapping of zero-sound and particle-hole modes
In this paper the solutions of the zero-sound dispersion equation in the
random phase approximation (RPA) are considered. The calculation of the damped
zero-sound modes \omega_s(k) (complex frequency of excitation) in the nuclear
matter is presented. The method is based on the analytical structure of the
polarization operators \Pi(\omega,k). The solutions of two dispersion equations
with \Pi(\omega,k) and with Re(\Pi(\omega,k)) are compared. It is shown that in
the first case we obtain one-valued smooth solutions without "thumb-like"
forms. Considering the giant resonances in the nuclei as zero-sound excitations
we compare the experimental energy and escape width of the giant dipole
resonance (GDR) in the nucleus A with \omega_s(k) taken at a definite wave
vector k=k_A.Comment: 14 pages, 5 figures; revised versio
The Orbit of the New Milky Way Globular Cluster FSR1716 =VVV-GC05
Indexación: Scopus.We use deep, multi-epoch near-IR images of the VISTA Variables in the Via Lictea (VVV) Survey to measure proper motions (PMs) of stars in the Milky Way globular cluster (GC) FSR1716 = VVV-GC05. The colormagnitude diagram of this object, made by using PM-selected members, shows an extended horizontal branch, nine confirmed RR Lyrae (RRL) members in the instability strip, and possibly several hotter stars extending to the blue. Based on the fundamental-mode (ab-type) RRL stars that move coherently with the cluster, we confirmed that FSR1716 is an Oosterhoff I GC with a mean period aPabn = 0.574 days. Intriguingly, we detect tidal extensions to both sides of this cluster in the spatial distribution of PM-selected member stars. Also, one of the confirmed RRabs is located -11 arcmin in projection from the cluster center, suggesting that FSR1716 may be losing stars due to the gravitational interaction with the Galaxy. We also measure radial velocities (RVs) for five cluster red giants selected using the PMs. The combination of RVs and PMs allow us to compute for the first time the orbit of this GC, using an updated Galactic potential. The orbit results to be confined within|Zmax| < 2.0 kpc, and has eccentricity 0.4 < e < 0.6, with perigalactic distance 1.5 < Rperi (kpc) < 2.3, and apogalactic distance 5.3 < Rapo (kpc) < 6.4. We conclude that, in agreement with its relatively low metallicity ([Fe/H] =-1.4 dex), this is an inner-halo GC plunging into the disk of the Galaxy. As such, this is a unique object with which to test the dynamical processes that contribute to the disruption of Galactic GCs. © 2018. The American Astronomical Society. All rights reserved.https://iopscience.iop.org/article/10.3847/1538-4357/aacd0
Fluctuation induced hopping and spin polaron transport
We study the motion of free magnetic polarons in a paramagnetic background of
fluctuating local moments. The polaron can tunnel only to nearby regions of
local moments when these fluctuate into alignment. We propose this fluctuation
induced hopping as a new transport mechanism for the spin polaron. We calculate
the diffusion constant for fluctuation induced hopping from the rate at which
local moments fluctuate into alignment. The electrical resistivity is then
obtained via the Einstein relation. We suggest that the proposed transport
mechanism is relevant in the high temperature phase of the Mn pyrochlore
colossal magneto resistance compounds and Europium hexaboride.Comment: 8 pages, 3 figure
Photon-assisted tunneling in a Fe8 Single-Molecule Magnet
The low temperature spin dynamics of a Fe8 Single-Molecule Magnet was studied
under circularly polarized electromagnetic radiation allowing us to establish
clearly photon-assisted tunneling. This effect, while linear at low power,
becomes highly non-linear above a relatively low power threshold. This
non-linearity is attributed to the nature of the coupling of the sample to the
thermostat.These results are of great importance if such systems are to be used
as quantum computers.Comment: 4 pages, 4 figure
Generic Business Model Types for Enterprise Mashup Intermediaries
The huge demand for situational and ad-hoc applications desired by the mass of business end users led to a new kind of Web applications, well-known as Enterprise Mashups. Users with no or limited programming skills are empowered to leverage in a collaborative manner existing Mashup components by combining and reusing company internal and external resources within minutes to new value added applications. Thereby, Enterprise Mashup environments interact as intermediaries to match the supply of providers and demand of consumers. By following the design science approach, we propose an interaction phase model artefact based on market transaction phases to structure required intermediary features. By means of five case studies, we demonstrate the application of the designed model and identify three generic business model types for Enterprise Mashups intermediaries (directory, broker, and marketplace). So far, intermediaries following a real marketplace business model don’t exist in context of Enterprise Mashups and require further research for this emerging paradigm
Calidad de vida y sus factores determinantes en universitarios españoles de Ciencias de la Salud
La calidad de vida en la población universitaria
adquiere una especial importancia ya que permite
obtener información sobre las condiciones de vida
de los universitarios y, sobre todo, de cómo éstos las perciben.
Objetivo: Evaluar la calidad de vida de los universitarios
que cursan estudios en ciencias de la salud y su
relación con diferentes factores tales como: hábitos de
vida, parámetros antropométricos y la influencia de las
distintas variables sobre su percepción.
Material y Método: Estudio transversal de una muestra
de 1.753 estudiantes de ciencias de la salud de nueve
universidades españolas con diseño muestral aleatorio y
estatrificado según curso y facultad al que se le aplicó
un cuestionaro ad hoc que recogía todas las variables a
estudio.
Resultados: La calidad de vida percibida por los participantes
fue Me = 75. Los factores explorados de la calidad
de vida se co-relacionaron significativamente con la
percepción global de calidad de vida de los estudiantes
(p<0,001). Se establecieron 3 dimensiones y el impacto de
cada una de ellas sobre la percepción de calidad de vida
global fue p<0,001. Los varones percibieron mejor calidad
de vida que las mujeres y también los estudiantes con
menor Índice de Masa Corporal (IMC).
Conclusión: Los universitarios son una población clave
para realizar actividades de promoción y prevención
de la salud por lo que resulta necesario crear mejores infraestucturas
y recursos educativos para mejorar la CV y
fomentar hábitos y estilos de vida saludable con especial
atención en la alimentación y la realización de una adecuada
actividad física.Abstract
Introduction: The quality of life of university students
acquires special importance because it provides information
about their life conditions and especially how they
perceive it.
Objetive: Evaluate the quality of life of students who
are enrolled in health science studies and its relation with
the following diverse factors: life and dietetic habits, anthropometric
parameters and the influence of distinct
variables on their perception.
Methods: Transversal study of a sample of 1753 health
science degree students of nine Spanish universities with
a randomized design and stratified by course and faculty
for which we applied an ad hoc questionnaire that considered
all study variables.
Results: The quality of life (QoL) perceived by the
participants had a Median of 75. The factors that were
explored about the quality of life correlated significantly
with their global perception of it (p<0.001). Three dimensions
were established and the impact of each one of them
on their global perception of QoL was p<0.001. Men perceived
better QoL then women and the students with lower
Body Mass Index (BMI).
Conclusions: University students are a key population
for realizing health promotion and prevention activities
therefore it is necessary to develop and provide better
infrastructures and educative resources in order to enhance
their QoL and to promote healthier habits and life
styles with special attention on dietetics habits and the
performance of an adequate physical activity
Dipolar-controlled spin tunneling and relaxation in molecular magnets
Spin tunneling in molecular magnets controlled by dipole-dipole interactions
(DDI) in the disordered state has been considered numerically on the basis of
the microscopic model using the quantum mean-field approximation. In the actual
case of a strong DDI spin coherence is completely lost and there is a slow
relaxation of magnetization, described by t^{3/4} at short times. Fast
precessing nuclear spins, included in the model microscopically, only
moderately speed up the relaxation.Comment: 10 pages, 9 figures, to be published in EPJ
The Absence of Caspase-8 in the Dopaminergic System Leads to Mild Autism-like Behavior
In the last decade, new non-apoptotic roles have been ascribed to apoptotic caspases. This family of proteins plays an important role in the sculpting of the brain in the early stages of development by eliminating excessive and nonfunctional synapses and extra cells. Consequently, impairments in this process can underlie many neurological and mental illnesses. This view is particularly relevant to dopamine because it plays a pleiotropic role in motor control, motivation, and reward processing. In this study, we analyze the effects of the elimination of caspase-8 (CASP8) on the development of catecholaminergic neurons using neurochemical, ultrastructural, and behavioral tests. To do this, we selectively delete the CASP8 gene in cells that express tyrosine hydroxylase with the help of recombination through the Cre-loxP system. Our results show that the number of dopaminergic neurons increases in the substantia nigra. In the striatum, the basal extracellular level of dopamine and potassium-evoked dopamine release decreased significantly in mice lacking CASP8, clearly showing the low dopamine functioning in tissues innervated by this neurotransmitter. This view is supported by electron microscopy analysis of striatal synapses. Interestingly, behavioral analysis demonstrates that mice lacking CASP8 show changes reminiscent of autism spectrum disorders (ASD). Our research reactivates the possible role of dopamine transmission in the pathogenesis of ASD and provides a mild model of autism
Nanoflowers Versus Magnetosomes Comparison Between Two Promising Candidates for Magnetic Hyperthermia Therapy
Magnetic Fluid Hyperthermia mediated by iron oxide nanoparticles is one of the most promising therapies for cancer treatment. Among the different candidates, magnetite and maghemite nanoparticles have revealed to be some of the most promising candidates due to both their performance and their biocompatibility. Nonetheless, up to date, the literature comparing the heating efficiency of magnetite and maghemite nanoparticles of similar size is scarce. To fill this gap, here we provide a comparison between commercial Synomag Nanoflowers pure maghemite and bacterial magnetosomes pure magnetite synthesized by the magnetotactic bacterium Magnetospirillum gryphiswaldense of amp; 10216;D amp; 10217; amp; 8776; 40 45 nm. Both types of nanoparticles exhibit a high degree of crystallinity and an excellent degree of chemical purity and stability. The structural and magnetic properties in both nanoparticle ensembles have been studied by means of X Ray Diffraction, Transmission Electron Microscopy, X Ray Absorption Spectroscopy, and SQUID magnetometry. The heating efficiency has been analyzed in both systems using AC magnetometry at several field amplitudes 0 88 mT and frequencies 130, 300, and 530 kH
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