47 research outputs found
Nonextensive thermodynamic functions in the Schr\"odinger-Gibbs ensemble
Schr\"odinger suggested that thermodynamical functions cannot be based on the
gratuitous allegation that quantum-mechanical levels (typically the orthogonal
eigenstates of the Hamiltonian operator) are the only allowed states for a
quantum system [E. Schr\"odinger, Statistical Thermodynamics (Courier Dover,
Mineola, 1967)]. Different authors have interpreted this statement by
introducing density distributions on the space of quantum pure states with
weights obtained as functions of the expectation value of the Hamiltonian of
the system.
In this work we focus on one of the best known of these distributions, and we
prove that, when considered in composite quantum systems, it defines partition
functions that do not factorize as products of partition functions of the
noninteracting subsystems, even in the thermodynamical regime. This implies
that it is not possible to define extensive thermodynamical magnitudes such as
the free energy, the internal energy or the thermodynamic entropy by using
these models. Therefore, we conclude that this distribution inspired by
Schr\"odinger's idea can not be used to construct an appropriate quantum
equilibrium thermodynamics.Comment: 32 pages, revtex 4.1 preprint style, 5 figures. Published version
with several changes with respect to v2 in text and reference
La sostenibilidad en la arquitectura industrializada: cerrando el ciclo de los materiales
The condition of sustainability, from a physical point of view, can be defined as the closure of the material cycle. This is reached in determined systems, in the absence of residual flows, and in which resources are constantly recycled. Such systems can encounter serious obstacles in the productive model that characterises the majority of contemporary industry. The productive model, born during the Industrial Revolution, can be summarised by the following lineal sequence: extraction > manufacture > use > residue. In contrast, this research focuses on a productive model from the ecological industry, based on the example of the biosphere as a recycling machine. Requiring the elimination of the concept of residues, the system can be summarised by the following continuous cycle: recycling-manufacturing-use-recycling.
The hypothesis posed is as follows: using technology presently available, represented by the lightweight modular construction that is commercialised by renting (making it possible to return the modules to the factory once their useful life is over, therefore recuperating resources), a management system capable to close the material cycle at least to 90% can be developed. (conventional building construction currently manages a recycling value of 10% of used resources).La condición de sostenibilidad, desde el punto de vista fÃsico, puede ser definida como el cierre de los ciclos materiales, alcanzándose éste en un sistema determinado cuando no existen flujos de residuos sino que los recursos se reciclan constantemente. Tal condición encuentra un fuerte obstáculo en el modelo productivo que caracteriza a la mayor parte de la industria contemporánea, nacido en la revolución industrial, que puede sintetizarse en la secuencia lineal extracción > fabricación > uso > residuo. En oposición a ello, el modelo productivo en el que se centra la investigación que aquà se presenta es la ecologÃa industrial y se basa en el ejemplo de la biosfera como máquina de reciclar. Supone la eliminación del concepto de residuo y puede resumirse en el ciclo continuo de reciclaje-fabricación-uso-reciclaje.
La hipótesis planteada consiste en que, a partir de los sistemas de construcción modular ligera que se comercializan bajo el sistema de alquiler (que hace posible que los módulos regresen a la fábrica una vez cumplida su vida útil, recuperándose sus componentes) se puede desarrollar un sistema de gestión de los recursos empleados en el ciclo de vida de los edificios capaz de cerrar los ciclos materiales hasta en un 90% (en la construcción convencional se alcanza un 10%)
La sostenibilidad en la arquitectura industrializada: cerrando el ciclo de los materiales
Recent tectonic and morphostructural evolution of Byers Peninsula (Antarctica): insight into the development of the South Shetland Islands and Bransfield Basin
Byers Peninsula forms the western extremity of the Livingston Island (Antarctica) in the continental South Shetland Block. This tectonic block is bounded by the South Shetland Trench to the north, the Bransfield back-arc basin to the south, and extends to the South Scotia Ridge on the east. Westwards it is connected to the Antarctic Plate by a broad deformation zone located at the southern end of the Hero Fracture Zone. In Byers Peninsula we analyzed more than 1,200 lineaments, and 359 fault planes from 16 sites, both in sedimentary and intrusive igneous rocks. Statistical analysis of lineaments and mesoscopic fractures, with a length varying between 31 and 1,555 m, shows a NW-SE maximum trend, with two NE-SW and ENE-WSW secondary maximums. Fault orientation analysis shows similar trends suggesting that most of the lineaments correspond to fractures. Due to the absence of striated faults and the lack of kinematic evidence on the regime in most of the analyzed faults we have used the Search Grid paleostress determination method. The results obtained allow us to improve and complete the data on the recent evolution of the South Shetland Block. In this complex geodynamic setting, Byers Peninsula has been subjected to NNW-SSE to NNE-SSW extension related to Bransfield Basin opening and NE-SW and NW-SE local compressions respectively associated to Scotia-Antarctic plate convergence and the South Shetland Trench subduction.La PenÃnsula Byers se localiza en el extremo occidental de la Isla Livingston (Antártida) que pertenece al bloque continental de las Shetland del Sur. Este bloque tectónico está limitado al norte por la Fosa de las Shetland del Sur, al sur por la cuenca de trasarco de Bransfield, y hacia el este se extiende por la Dorsal Sur de Scotia. Hacia el oeste conecta con la placa Antártica a través de una amplia zona de deformación localizada en la prolongación meridional de la Zona de Fractura Hero. En este trabajo se han analizado conjuntamente más de 1.200 lineamientos, asà como 359 planos de fallas en 16 estaciones en rocas sedimentarias e Ãgneas de la PenÃnsula Byers. El análisis estadÃstico de los lineamientos y las fracturas a escala mesoscópica, con una longitud que oscila entre 31 y 1.555 m, muestran una orientación máxima NO-SE, con dos máximos secundarios de dirección NE-SO y ENE-OSO. El análisis de las fracturas muestra orientaciones similares que sugieren que gran parte de estos lineamientos están relacionados con fracturas. La ausencia de indicadores cinemáticos de calidad en la mayor parte de las fracturas sólo nos ha permitido aplicar el método de Redes de Búsqueda para el cálculo de paleoesfuerzos. Los resultados obtenidos son compatibles con los obtenidos en otros sectores del Bloque de las Shetland del Sur. En este complejo contexto geodinámico, la PenÃnsula Byers ha estado sometida a extensión NNW-SSE/ NNE-SSW ligada a la apertura de la cuenca de Bransfield, asà como a compresión local NE-SO y NO-SE asociada respectivamente a la convergencia entre las placas Scotia y Antártica, y a la subducción en la Fosa de las Shetland del Sur
Statistics and Nos\'e formalism for Ehrenfest dynamics
Quantum dynamics (i.e., the Schr\"odinger equation) and classical dynamics
(i.e., Hamilton equations) can both be formulated in equal geometric terms: a
Poisson bracket defined on a manifold. In this paper we first show that the
hybrid quantum-classical dynamics prescribed by the Ehrenfest equations can
also be formulated within this general framework, what has been used in the
literature to construct propagation schemes for Ehrenfest dynamics. Then, the
existence of a well defined Poisson bracket allows to arrive to a Liouville
equation for a statistical ensemble of Ehrenfest systems. The study of a
generic toy model shows that the evolution produced by Ehrenfest dynamics is
ergodic and therefore the only constants of motion are functions of the
Hamiltonian. The emergence of the canonical ensemble characterized by the
Boltzmann distribution follows after an appropriate application of the
principle of equal a priori probabilities to this case. Once we know the
canonical distribution of a Ehrenfest system, it is straightforward to extend
the formalism of Nos\'e (invented to do constant temperature Molecular Dynamics
by a non-stochastic method) to our Ehrenfest formalism. This work also provides
the basis for extending stochastic methods to Ehrenfest dynamics.Comment: 28 pages, 1 figure. Published version. arXiv admin note: substantial
text overlap with arXiv:1010.149
Dwarf pomegranate (Punica granatum L. var. nana): source of 5-HMF and bioactive compounds with applications in the protection of woody crops
While the properties of edible pomegranate varieties have been widely explored, there is little information on ornamental types. In this study, possible alternatives for the valorization of dwarf pomegranate fruits have been explored. The characterization of their hydromethanolic extract by gas chromatography−mass spectrometry evidenced the presence of high contents of 5-hydroxymethylfurfural (a carbon-neutral feedstock for the production of fuels and other chemicals) and β- and γ-sitosterol stereoisomers. The microbicidal activity of the crude extract, both alone and in a conjugate complex with chitosan oligomers (COS), was investigated against three plant pathogenic microorganisms that cause significant losses in woody crops: Erwinia amylovora, E. vitivora, and Diplodia seriata. In in vitro assays, a strong synergistic behavior was found after conjugation of the bioactive constituents of the fruit extract with COS, resulting in minimum inhibitory concentration (MIC) values of 750 and 375 μg·mL−1 against E. amylovora and E. vitivora, respectively, and an EC90 value of 993 μg·mL−1 against D. seriata. Hence, extracts from the non-edible fruits of this Punicaceae may hold promise as a source of high value-added phytochemicals or as environmentally friendly agrochemicals
Generalized Central Limit Theorem and Renormalization Group
We introduce a simple instance of the renormalization group transformation in
the Banach space of probability densities. By changing the scaling of the
renormalized variables we obtain, as fixed points of the transformation, the
L\'evy strictly stable laws. We also investigate the behavior of the
transformation around these fixed points and the domain of attraction for
different values of the scaling parameter. The physical interest of a
renormalization group approach to the generalized central limit theorem is
discussed.Comment: 16 pages, to appear in J. Stat. Phy
Groundwater hydrochemistry of Rajnandgaon district, Chhattisgarh, Central India
The spreading of fluorosis diseases in Central India related to high concentrations of fluoride ion (F−) is a cause of major concern. In this work, the hydrochemistry of the aquifers related to Seonath River, in Rajnandgaon district, Chhattisgarh state, India, has been studied, focusing on the presence and sources of F−. Hydrochemical parameters were analyzed in the post-monsoon season in 160 wells located in nine tehsils, finding F− concentrations ranging from 0.6 to 18.5 mg L−1. Seasonal variations were also studied in Chhuikhadan tehsil, in which the highest F− values were registered, finding a noticeable enrichment in the pre-monsoon months. In many locations of the district, F− concentrations exceeded the recommended value of 1.5 mg L−1, which have led to the appearance of several health issues. Multidimensional analysis statistical methods were adopted to investigate the sources of F−, and the mineralization of bedrock elements into the groundwater was observed to be the primary source