Duality between k-essence and Rastall gravity

The k-essence theory with a power-law function of $(\partial\phi)^2$ and Rastall's non-conservative theory of gravity with a scalar field are shown to have the same solutions for the metric under the assumption that both the metric and the scalar fields depend on a single coordinate. This equivalence (called k-R duality) holds for static configurations with various symmetries (spherical, plane, cylindrical, etc.) and all homogeneous cosmologies. In the presence of matter, Rastall's theory requires additional assumptions on how the stress-energy tensor non-conservation is distributed between different contributions. Two versions of such non-conservation are considered in the case of isotropic spatially flat cosmological models with a perfect fluid: one (R1) in which there is no coupling between the scalar field and the fluid, and another (R2) in which the fluid separately obeys the usual conservation law. In version R1 it is shown that k-R duality holds not only for the cosmological models themselves but also for their adiabatic perturbations. In version R2, among other results, a particular model is singled out that reproduces the same cosmological expansion history as the standard $\Lambda$CDM model but predicts different behaviors of small fluctuations in the k-essence and Rastall frameworks.Comment: 10 pages, no figures. Two references adde

Modelamiento y simulación de un sistema no convencional de levantamiento multifasico

The importance of the multiphase flow is caused in that when the produced fluid is displaced from the reservoir to the surface, energy is released in both the vertical and horizontal flow; this energy or pressure is possessed by the fluid while it is in the reservoir. Therefore, it is required to make a good design teams well, flowlines, throttles, separators and other connections. For optimum design, it is necessary to conduct a detailed study of the behavior of multiphase flow in each component. This paper presents the software developed which allows determine through correlations and mechanistic models, the profiles of pressure and temperature that occur along the pipes. The software was developed in a graphic interface in Java programming language and was validated with PIPESIM commercial software. In this way it can be further studied the behavior of multiphase flow in vertical and horizontal pipe.La importancia del flujo multifásico se origina en que cuando el fluido producido se desplaza desde el yacimiento hacia la superficie, se libera energía tanto en el flujo vertical como en el flujo horizontal; esta energía o presión está inmersa en el fluido mientras está en el yacimiento. Por lo tanto, es necesario realizar un buen diseño de los equipos del pozo, líneas de flujo, estranguladores, separadores, y demás conexiones. Para un diseño óptimo, es necesario realizar un estudio detallado del comportamiento del flujo multifásico en cada componente. El presente artículo presenta el desarrollo de un Software que permite determinar mediante correlaciones y modelos mecanísticos los perfiles de presión y temperatura que se presentan a lo largo de las tuberías. El Software está desarrollado en una interfaz gráfica en lenguaje de programación Java y fue validado en el Software comercial PIPESIM. De esta manera se podrá estudiar más a fondo el comportamiento del flujo multifásico en tubería vertical y horizontal

La relación entre gestión familiar y desempeño en las pymes: los efectos mediadores del uso de sistemas de control de gestión y los logros en la innovación tecnológica

We study the influence of family management on firm performance in SMEs, analysing the mediating role of management control systems and the achievement of technological innovation in the former relationship. We used data from a survey addressed to firm managers in Murcia (Spain) and we checked our models using Partial Least Squares (PLS). We find empirical support for a positive mediating influence of management control systems and the achievement of technological innovation on the relation between family management and firm performance. Hence, the higher is the use of management control systems and the greater the creation of technological innovation, the more likely it is that family-managed firms perform better. Moreover, we show that the use of management control systems has both a direct and indirect –through its incidence on the obtaining of TI- influence on firm performance. Therefore, our paper stresses the importance of considering that family managers may utilize management control systems and the obtaining of technological innovation as a mean to improve firm performanceUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Identification, characterization and localization of chagasin, a tight-binding cysteine protease inhibitor in Trypanosoma cruzi

Lysosomal cysteine proteases from mammalian cells and plants are regulated by endogenous tight-binding inhibitors from the cystatin superfamily. The presence of cystatin-like inhibitors in lower eukaryotes such as protozoan parasites has not yet been demonstrated, although these cells express large quantities of cysteine proteases and may also count on endogenous inhibitors to regulate cellular proteolysis. Trypanosoma cruzi, the causative agent of Chagas heart disease, is a relevant model to explore this possibility because these intracellular parasites rely on their major lysosomal cysteine protease (cruzipain) to invade and multiply in mammalian host cells. Here we report the isolation, biochemical characterization, developmental stage distribution and subcellular localization of chagasin, an endogenous cysteine protease inhibitor in T. cruzi. We used high temperature induced denaturation to isolate a heat-stable cruzipain-binding protein (apparent molecular mass, 12 kDa) from epimastigote lysates. This protein was subsequently characterized as a tight-binding and reversible inhibitor of papain-like cysteine proteases. Immunoblotting indicated that the expression of chagasin is developmentally regulated and inversely correlated with that of cruzipain. Gold-labeled antibodies localized chagasin to the flagellar pocket and cytoplasmic vesicles of trypomastigotes and to the cell surface of amastigotes. Binding assays performed by probing living parasites with fluorescein (FITC)-cruzipain or FITC-chagasin revealed the presence of both inhibitor and protease at the cell surface of amastigotes. The intersection of chagasin and cruzipain trafficking pathways may represent a checkpoint for downstream regulation of proteolysis in trypanosomatid protozoa

First Record of Leea guineensis (Vitaceae) in Cuban Scientific Literature

The presence of Leea guineensis G. Don. was confirmed in Cuba. It is a widely cultivated alochtonous species used in Cuba as ornameltal plants, which had not been previously registered in the scientific literature of the country. Several botanical procedures (collections, specialized catalogs, descriptions, and scientific illustrations) were applied. It is a new taxon of the genus in the country. A key is suggested as a way to distinguish it from other genera of the Vitaceae family

Essential Notes on the Passiflora incarnata-Agraulis vanillae insularis Relation

Context: The local vegetation was studied to identify elements that could host butterfly rearing (Lepidoptera: Papilionoidea) in the butterfly refuge at the Camaguey’s Botanical Park Aim: To unveil the nomenclature, taxonomy, phenotypical characterization, differences from akin taxa, distribution, and ethnobiological traits of a host plant (Passiflora incarnata L.), and one of the butterflies that lives in it (Agraulis vanillae insularis Maynard, 1889). Methods: Field observation, work with biological collections, digital image processing, specimen identification through descriptive catalogs and analytical keys, experimental breeds in controlled conditions. Results: The recorded history of P. incarnata L. in Cuba was reconstructed, and the origin of the germplasm found at the Camaguey’s Botanical Park was elucidated. A. vanillae insularis Maynard (1889) demonstrated a potential as a host plant in Cuba. Different criteria were defined to contrast the two taxa with their akin. The feasibility of using the plant to rear butterflies for exhibition purposes was discussed. Conclusions: Due to the frequency P. incarnata L. is cultivated in Cuba, it should be acknowledged as part of the economic flora of the nation. Considering that it acts as a host plant at the Camaguey’s Botanical Park, and is capable of host the rearing of A. vanillae insularis Maynard (1889) butterflies, which have the potential to be included in the butterfly refuge under construction in the park