On the Unification of Process Semantics: Logical Semantics

We continue with the task of obtaining a unifying view of process semantics by considering in this case the logical characterization of the semantics. We start by considering the classic linear time-branching time spectrum developed by R.J. van Glabbeek. He provided a logical characterization of most of the semantics in his spectrum but, without following a unique pattern. In this paper, we present a uniform logical characterization of all the semantics in the enlarged spectrum. The common structure of the formulas that constitute all the corresponding logics gives us a much clearer picture of the spectrum, clarifying the relations between the different semantics, and allows us to develop generic proofs of some general properties of the semantics.Comment: In Proceedings SOS 2011, arXiv:1108.279

Oral administration of cobalt acetate alters milk fatty acid composition, consistent with an inhibition of stearoyl-coenzyme A desaturase in lactating ewes

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An Exactly Conservative Integrator for the n-Body Problem

The two-dimensional n-body problem of classical mechanics is a non-integrable Hamiltonian system for n > 2. Traditional numerical integration algorithms, which are polynomials in the time step, typically lead to systematic drifts in the computed value of the total energy and angular momentum. Even symplectic integration schemes exactly conserve only an approximate Hamiltonian. We present an algorithm that conserves the true Hamiltonian and the total angular momentum to machine precision. It is derived by applying conventional discretizations in a new space obtained by transformation of the dependent variables. We develop the method first for the restricted circular three-body problem, then for the general two-dimensional three-body problem, and finally for the planar n-body problem. Jacobi coordinates are used to reduce the two-dimensional n-body problem to an (n-1)-body problem that incorporates the constant linear momentum and center of mass constraints. For a four-body choreography, we find that a larger time step can be used with our conservative algorithm than with symplectic and conventional integrators.Comment: 17 pages, 3 figures; to appear in J. Phys. A.: Math. Ge

Genetic differentiation between natural populations of Drosophila subobscura in the Western Mediterranean Area with respect to chromosomal variation

International audienc

Psychological well-being among older adults during the COVID-19 outbreak: A comparative study of the young-old and the old-old adults

The COVID-19 outbreak could be considered as an uncontrollable stressful life event. Lockdown measures have provoked a disruption of daily life with a great impact over older adults' health and well-being. Nevertheless, eudaimonic well-being plays a protective role in confronting adverse circumstances, such as the COVID-19 situation. This study aims to assess the association between age and psychological well-being (personal growth and purpose in life). Young-old (60-70 years) and old-old (71-80 years) community-dwelling Spaniards (N = 878) completed a survey and reported on their sociodemographic characteristics and their levels of health, COVID-19 stress-related, appraisal, and personal resources. Old-old did not evidence poorer psychological well-being than young-old. Age has only a negative impact on personal growth. The results also suggest that the nature of the COVID-19 impact (except for the loss of a loved one) may not be as relevant for the older adults' well-being as their appraisals and personal resources for managing COVID-related problems. In addition, these results suggest that some sociodemographic and health-related variables have an impact on older adults' well-being. Thus, perceived-health, family functioning, resilience, gratitude, and acceptance had significant associations with both personal growth and purpose in life. Efforts to address older adults' psychological well-being focusing on older adults' personal resources should be considered

Thoracolumbar fractures without neurological impairment : a review of diagnosis and treatment

An appropriate protocol and unified management of thoracolumbar fractures without neurological impairment has not been well defined. This review attempts to elucidate some controversies regarding diagnostic tools, the ability to define the most appropriate treatment of classification systems and the evidence for conservative and surgical methods based on the recent literature

Logística inversa de residuos agroquímicos en Argentina: resolución heurística y exacta

Argentina es uno de los principales exportadores de productos agrícolas del mundo, localizándose gran parte de esta producción en la región pampeana. Debido a su enorme escala, esta actividad, además de generar importantes ingresos a nuestro país, también origina una gran cantidad de residuos especiales, entre ellos, los envases de los agroquímicos. Son conocidos los problemas ambientales y económicos que genera el incorrecto manejo de estos residuos por poseer sustancias que representan un riesgo para la salud y el medio ambiente. Teniendo en cuenta esta problemática, la Universidad Nacional del Sur (UNS) y la Universidad Provincial del Sudoeste (UPSO), proponen diseñar un sistema de reciclado de dichos envases en la región que comprende los veintiún municipios del sudoeste bonaerense (SOB). En el marco de este proyecto, el presente trabajo consistió en la optimización de la red logística de recolección de los residuos agroquímicos y la evaluación de la localización de la planta de tratamiento de los mismos. El modelado de la red se abordó como un problema CVRP (Capacitated Vehicle Routing Problem). Se consideraron distintas frecuencias de recolección y se resolvió mediante técnicas exactas y heurísticas.Sociedad Argentina de Informática e Investigación Operativ

A large geometric distortion in the first photointermediate of rhodopsin, determined by double-quantum solid-state NMR

Double-quantum magic-angle-spinning NMR experiments were performed on 11,12-C-13(2)-retinylidene-rhodopsin under illumination at low temperature, in order to characterize torsional angle changes at the C11-C12 photoisomerization site. The sample was illuminated in the NMR rotor at low temperature (similar to 120 K) in order to trap the primary photointermediate, bathorhodopsin. The NMR data are consistent with a strong torsional twist of the HCCH moiety at the isomerization site. Although the HCCH torsional twist was determined to be at least 40A degrees, it was not possible to quantify it more closely. The presence of a strong twist is in agreement with previous Raman observations. The energetic implications of this geometric distortion are discussed