394 research outputs found
Leibniz algebras of Heisenberg type
We introduce and provide a classification theorem for the class of Heisenberg-Fock Leibniz algebras.
This category of algebras is formed by those Leibniz algebras L whose corresponding Lie algebras are Heisenberg
algebras Hn and whose Hn-modules I, where I denotes the ideal generated by the squares of elements of L, are
isomorphic to Fock modules. We also consider the three-dimensional Heisenberg algebra H3 and study three classes
of Leibniz algebras with H3 as corresponding Lie algebra, by taking certain generalizations of the Fock module.
Moreover, we describe the class of Leibniz algebras with Hn as corresponding Lie algebra and such that the action
I × Hn ! I gives rise to a minimal faithful representation of Hn. The classification of this family of Leibniz
algebras for the case of n = 3 is given
Hospital mortality in acute coronary syndrome: differences related to gender and use of percutaneous coronary procedures
<p>Abstract</p> <p>Background</p> <p>To identify differences among men and women with acute coronary syndrome in terms of in-hospital mortality, and to assess whether these differences are related to the use of percutaneous cardiovascular procedures.</p> <p>Methods</p> <p>Observational study based on the Minimum Basic Data Set. This encompassed all episodes of emergency hospital admissions (46,007 cases, including 16,391 women and 29,616 men) with a main diagnosis of either myocardial infarction or unstable angina at 32 hospitals within the Andalusian Public Health System over a four-year period (2000–2003). The relationship between gender and mortality was examined for the population as a whole and for stratified groups depending on the type of procedures used (diagnostic coronary catheterisation and/or percutaneous transluminal coronary angioplasty). These combinations were then adjusted for age group, main diagnosis and co-morbidityharlson score).</p> <p>Results</p> <p>During hospitalisation, mortality was 9.6% (4,401 cases out of 46,007), with 11.8% for women and 8.3% for men. There were more deaths among older patients with acute myocardial infarction and greater co-morbidity. Lower mortality was shown in patients undergoing diagnostic catheterisation and/or PTCA. After adjusting for age, diagnosis and co-morbidity, mortality affected women more than men in the overall population (OR 1.14, 95% CI: 1.06–1.22) and in the subgroup of patients where no procedure was performed (OR 1.16, 95% CI: 1.07–1.24). Gender was not an explanatory variable in the subgroups of patients who underwent some kind of procedure.</p> <p>Conclusion</p> <p>Gender has not been associated to in-hospital mortality in patients who undergo some kind of percutaneous cardiovascular procedure. However, in the group of patients without either diagnostic catheterisation or angioplasty, mortality was higher in women than in men.</p
Electric-field tuning of the valley splitting in silicon corner dots
We perform an excited state spectroscopy analysis of a silicon corner dot in
a nanowire field-effect transistor to assess the electric field tunability of
the valley splitting. First, we demonstrate a back-gate-controlled transition
between a single quantum dot and a double quantum dot in parallel that allows
tuning the device in to corner dot formation. We find a linear dependence of
the valley splitting on back-gate voltage, from to with a slope of (or equivalently a slope
of with respect to the effective field). The
experimental results are backed up by tight-binding simulations that include
the effect of surface roughness, remote charges in the gate stack and discrete
dopants in the channel. Our results demonstrate a way to electrically tune the
valley splitting in silicon-on-insulator-based quantum dots, a requirement to
achieve all-electrical manipulation of silicon spin qubits.Comment: 5 pages, 3 figures. In this version: Discussion of model expanded;
Fig. 3 updated; Refs. added (15, 22, 32, 34, 35, 36, 37
The Role of Orbital Nesting in the Superconductivity of Iron-Based Superconductors
We analyze the magnetic excitations and the spin-mediated superconductivity in iron-based superconductors within a low energy model that operates in the band basis, but fully incorporates the orbital character of the spin excitations. We show how the orbital selectivity, encoded in our low energy description, simplifies substantially the analysis and allows for analytical treatments, while retaining all the main features of both spin excitations and gap functions computed using multiorbital models. Importantly, our analysis unveils the orbital matching between the hole and electron pockets as the key parameter to determine the momentum dependence and the hierarchy of the superconducting gaps, instead of the Fermi surface matching, as in the common nesting scenario
Evaluating the psychometric properties of the Exercise Dependence Scale-Revised (EDS-R) in a Spanish Sample.
Introduction: There are several instruments to evaluate behavioural addictions. Furthermore, several
specific scales have been developed to assess various aspects of exercise dependence. Nevertheless,
in Spain there is a lack of specific instruments designed to assess exercise dependence.
Objective: This study aims to examine the psychometric properties of a Spanish version of the Exercise
Dependence Scale-Revised.
Method: 175 university students who were regular exercisers (m=59.11, sd=15.89) took part in the
study. They were requested to complete the eds-r, as well as the General Addiction Scale. The requirement
to take part in the study was to exercise a minimum of four times per week.
Results: Findings provide initial support for the psychometric properties of the scale as its internal
consistency (Cronbach’s alpha: 0.907), and construct and convergent validity with the eag-rc (r=.559;
p<.001) are adequate. In addition, its structure did not need to be modified, as it kept the 21 original
items from the American version. Factor analysis yielded a five-factor structure (tolerance, loss of control,
continuity, intensity, and withdrawal symptoms) which differ from the ones obtained in the original
(American) and French versions where seven factors were obtained. This correlated five-factor model
explains 50% of the variance.
Conclusion: This Spanish eds-r, which presents adequate psychometric properties, will provide researchers
and clinicians with specific data on this screening tool for assessing exercise dependence.
Further research is needed to confirm the current results and check its validity both in research and
clinical practice.2017-1
A revisit to the region of Collinder 132 using Carte du Ciel and Astrographic Catalogue plates
Aims. Based on stellar positions and proper motions, we aim to re-analyse the region of the controversial open cluster Collinder 132. Methods. We have developed a model which analyses the proper motion distribution and the stellar density to find moving groups. The astrometric data were obtained from four Carte du Ciel (CdC) and one Astrogaphic Catalogue (AC) plates of the Córdoba Astronomical Observatory collection (Argentina). Results. We detected an open cluster from the field stars and calculated the mean proper motion and the membership probabilities of the region's stars. We report new coordinates of its centre αc = 108\fdg347, δc = -31\fdg011, the components of mean proper motion μ αcosδ = -2.62±0.44 mas/yr, μδ = 4.79±0.88 mas/yr. Thirteen stars are astrometric members giving a value of 20' for the cluster angular diameter. Six stars fulfil the astrometric and photometric criteria for being cluster members and locate the cluster at 360 pc from the Sun. We propose a simple model for the analysis of the proper motion distribution of an association. We report the components of the association mean proper motion μαcosδ = -1.38±0.14 mas/yr, μδ = 2.26±0.16 mas/yr. We found 149 astrometric members, 11 of which have reliable photometric data that locate them betweeen 417 and 660 pc from the Sun.Este documento tiene una corrección (ver documento relacionado).Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica
Alcohol Protective Behavioral Strategies in Young Spanish Adults in the Community: A Prospective Study of Perceived Effi cacy and Social Norms
Background: Protective behavioral strategies (PBS) have been shown to
be useful for reducing excessive alcohol use and alcohol-related problems.
However, research on the explanatory factors of PBS is limited. This paper
prospectively examines the contribution of perceived effi cacy of PBS in
reducing alcohol-related consequences and perceived descriptive norms
of close peers´ PBS use in young adults. The mediating role of perceived
effi cacy of PBS between descriptive norms of PBS use and personal PBS
use is also examined. Method: Targeted sampling was used to recruit a
community-based sample of 339 young Spanish adults aged 18-25 years,
who completed baseline and two-month follow-up questionnaires. Three
types of PBS (serious harm reduction-SHR, manner of drinking-MOD, and
stopping/limiting drinking-SLD) were measured. Results: Both perceived
effi cacy and descriptive norms at baseline were positively associated with
personal PBS use (SHR, MOD and SLD) at follow-up. A partial mediation
effect of perceived effi cacy between descriptive norms and personal PBS
use was found for the three PBS subscales. Conclusions: Our fi ndings
support the usefulness of correcting misperceptions of PBS use by peers
in interventions aimed at reducing excessive drinking and alcohol-related
consequences in young adults in the community. Moreover, PBS perceived
effi cacy should be included as a component of these interventions.Antecedentes: las estrategias conductuales de protección (ECP)
han mostrado utilidad para reducir el consumo excesivo de alcohol y sus
problemas asociados, aunque la investigación sobre sus factores explicativos
es escasa. Este trabajo examina la contribución de la efi cacia percibida de
las ECP para reducir las consecuencias negativas del alcohol, y la norma
descriptiva percibida del uso de PBS de los iguales, en adultos jóvenes.
Además, analiza el papel mediador de la efi cacia percibida entre norma
descriptiva y ECP. Método: mediante muestreo dirigido a poblaciones
diana, 339 jóvenes españoles (18-25 años) comunitarios cumplimentaron
cuestionarios basal y de seguimiento (dos meses), midiéndose tres tipos de
ECP (reducción de daños-RR, forma de beber-FB, parar/limitar el consumo-
PLC). Resultados: efi cacia y norma se asociaron positivamente con el uso de
ECP (RR/FB/PLC) en el seguimiento. Para los tres tipos de ECP se detectó
un efecto de mediación parcial de la efi cacia percibida entre la norma y el uso
de ECP. Conclusiones: corregir percepciones erróneas del uso de ECP de los
iguales puede ser útil en las intervenciones dirigidas a reducir el uso excesivo
de alcohol y sus consecuencias en adultos jóvenes comunitarios, al igual que
la inclusión de la efi cacia percibida como uno de sus componentes
Twisted bilayered graphenes at magic angles and Casimir interactions: correlation-driven effects
Twisted bilayered graphenes at magic angles are systems housing long ranged
periodicity of Moir\'e pattern together with short ranged periodicity
associated with the individual graphenes. Such materials are a fertile ground
for novel states largely driven by electronic correlations. Here we find that
the ubiquitous Casimir force can serve as a platform for macroscopic
manifestations of the quantum effects stemming from the magic angle bilayered
graphenes properties and their phases determined by electronic correlations. By
utilizing comprehensive calculations for the electronic and optical response,
we find that Casimir torque can probe anisotropy from the Drude conductivities
in nematic states, while repulsion in the Casimir force can help identify
topologically nontrivial phases in magic angle twisted bilayered graphenes.Comment: 9 pages, 6 figures (main), 7 pages, 7 figures (supplementary);
provisionally accepted for publication in 2D Material
Predictors of vulnerability and aggression in severe intimate partner violence
Understanding the characteristics of victim vulnerability as well as the violence perpetrated by abusers against women in relationships is essential for professionals in the field who are adopting intervention measures. The current study aimed to examine the differences between severe (n = 805) and less severe (n = 805) intimate partner violence (IPV) as well as to identify the variables that predict severe IPV. Chi-square test and logistic regression analysis were used to examine the information from police reports on IPV in Catalonia (Spain) between 2016 and 2017, obtained through the Police Risk Assessment Questionnaire (PRAQ). In relation to the victims, isolation, minimization of abuse, fear of being seriously assaulted, substance abuse and pregnancy increased the risk of suffering severe IPV, while being in a new relationship and the existence of prior police reports diminished it. As for the aggressor, previous sexual aggression and abuse, degrading treatment, threats, harassment, control, and jealousy increased the probability of committing severe IPV. Some implications for intervening between aggressors and victims of IPV are discussed.2020-2
Predictores de vulnerabilidad en víctimas que sufren violencia severa contra la pareja en función de la tipología de su agresor
Este estudio analiza la información recogida mediante el Cuestionario Policial
de Valoración del Riesgo (CPVR) respecto de 722 denuncias presentadas en Cataluña
(España) en el 2017. Se comparó dos grupos de víctimas, aquellas maltratadas por
agresores antisociales (n=318) frente a aquellas cuyos maltratadores solo agreden
en el ámbito familiar (n=404). Los resultados de la prueba de árboles de regresión
indican que el miedo a ser agredida y la minimización del maltrato son los principales
predictores de VCP-S en las víctimas de agresores solo en familia, mientras que en las
víctimas de maltratadores antisociales el miedo a ser agredida es el mejor predictor de
esta clase de violencia. Es necesario incorporar en las herramientas de evaluación del
riesgo de VCP-S la percepción de la mujer sobre el riesgo de ser asesinada, e informar a
las víctimas de agresores solo en la familia del peligro de minimizar y justificar el
maltrato.2019-2
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