1,611 research outputs found
Atomistic long-term simulation of heat and mass transport
We formulate a theory of non-equilibrium statistical thermodynamics for ensembles of atoms or molecules. The theory is an application of Jayne's maximum entropy principle, which allows the statistical treatment of systems away from equilibrium. In particular, neither temperature nor atomic fractions are required to be uniform but instead are allowed to take different values from particle to particle. In addition, following the Coleman-Noll method of continuum thermodynamics we derive a dissipation inequality expressed in terms of discrete thermodynamic fluxes and forces. This discrete dissipation inequality effectively sets the structure for discrete kinetic potentials that couple the microscopic field rates to the corresponding driving forces, thus resulting in a closed set of equations governing the evolution of the system. We complement the general theory with a variational meanfield theory that provides a basis for the formulation of computationally tractable approximations. We present several validation cases, concerned with equilibrium properties of alloys, heat conduction in silicon nanowires and hydrogen desorption from palladium thin films, that demonstrate the range and scope of the method and assess its fidelity and predictiveness. These validation cases are characterized by the need or desirability to account for atomic-level properties while simultaneously entailing time scales much longer than those accessible to direct molecular dynamics. The ability of simple meanfield models and discrete kinetic laws to reproduce equilibrium properties and long-term behavior of complex systems is remarkable
Visible and near-infrared observations of asteroid 2012 DA14 during its closest approach of February 15, 2013
Near-Earth asteroid 2012 DA14 made its closest approach on February 15, 2013,
when it passed at a distance of 27,700 km from the Earth's surface. It was the
first time an asteroid of moderate size was predicted to approach that close to
the Earth, becoming bright enough to permit a detailed study from ground-based
telescopes. Asteroid 2012 DA14 was poorly characterized before its closest
approach. We acquired data using several telescopes on four Spanish
observatories: the 10.4m Gran Telescopio Canarias (GTC) and the 3.6m Telescopio
Nazionale Galileo (TNG), both in the El Roque de los Muchachos Observatory
(ORM, La Palma); the 2.2m CAHA telescope, in the Calar Alto Observatory
(Almeria); the f/3 0.77m telescope in the La Hita Observatory (Toledo); and the
f/8 1.5m telescope in the Sierra Nevada Observatory (OSN, Granada). We obtained
visible and near-infrared color photometry, visible spectra and time-series
photometry. Visible spectra together with color photometry of 2012 DA14 show
that it can be classified as an L-type asteroid, a rare spectral type with a
composition similar to that of carbonaceous chondrites. The time-series
photometry provides a rotational period of 8.95 +- 0.08 hours after the closest
approach, and there are indications that the object suffered a spin-up during
this event. The large amplitude of the light curve suggests that the object is
very elongated and irregular, with an equivalent diameter of around 18m. We
obtain an absolute magnitude of H_R = 24.5 +- 0.2, corresponding to H_V = 25.0
+- 0.2. The GTC photometry also gives H_V = 25.29 +- 0.14. Both values agree
with the value listed at the Minor Planet Center shortly after discovery. From
the absolute photometry, together with some constraints on size and shape, we
compute a geometric albedo of p_V = 0.44 +- 0.20, which is slightly above the
range of albedos known for L-type asteroids (0.082 - 0.405).Comment: 7 pages, 4 figures, 1 table. Accepted in A&A (June 17 2013
External stimuli help restore post-partum ovarian activity in Pelibuey sheep
Post-partum anestrus is a problem on farms, and its duration depends on the frequency and intensity of suckling which affects reproduction and production efficiency to become a determining economic factor. The aim of this study was to determine the post-partum reproductive response in ewe to a "male effect" with an ovulation induction protocol of five days using progesterone and the application of a metabolic restorative (MR; Metabolase ®). One hundred and twenty females were randomly assigned to one of four treatments: T1: Continuous suckling (CS; n = 29), T2: CS + MR (n = 29), T3: CS + Male Effect (ME; n = 32), and T4: CS + MR + ME. The percentage of females in ovulation, weight changes among females and lambs, the onset of estrus, calving, fecundity, and prolificacy were also determined. The ovulation percentage was higher in CS + ME and CS + MR + ME (75.0 and 73.3%) than in the other treatments. Weight changes in females and lambs were different among periods. The onset of estrus was similar for CS and CS + MR (25.9 ± 1.9 and 25.7 ± 0.7 h, respectively). The calving percentage was higher for CS + MR (86.2%) than other treatments. Male presence positively affected the postpartum cyclic ovarian re-establishment and the metabolic restorative could even improve the fertility of hair ewes in continuous suckling with similar hormone protocolKeywords: Male effect, metabolic stimulation, post-partum anestru
Estabilidad de patatas chips fritas en aceites vegetales de distinto grado de insaturación. Efecto del palmitato de ascorbilo durante el almacenamiento
Four vegetable oils with different polyunsaturated/saturated fatty acid ratio (P/S): 5.2 for sunflower oil, 3.,4 for canola rapeseed oil, 0.4 for a blend of palm oleic and canola rapeseed oil (80:20), and 0.3 for palm olein were assayed for stability of crisps fried in these oils during storage at 60º C. The action of ascorbyl palmitate with special attention to its synergistic effect on the natural antioxidants was also tested. by addition to the fried potatoes. The evolution of the oxidative stability was measured through peroxide value, quantitation of tocopherols and tocotrienols, and induction time (IT) by means of Rancimat. Oil degradation during frying was very low as both polar compound percentages and natural antioxidant had similar levels to those present in refined oils. Evolution of analytical parameters during storage results indicated that oil unsaturation degree or P/S had a much more importance on stability of the product than had the content and type of natural antioxidants and the addition of AP. Nevertheless, addition of AP to the fried potatoes had a significant effect resulting in higher retention of natural antioxidants, higher IT and lower PV at any storage timeSe estudia la evolución de la oxidación a 60º C en patatas fritas con cuatro aceites vegetales de distinta relación ácidos grasos poliinsaturados/saturados (P/S): 5,4 para el aceite de girasol, 3,4 para el aceite de canola, 0,4 para una mezcla de oleína de palma (80 %) y aceite de canola (20 %) y 0,3 para la oleína de palma. Se estudia igualmente la influencia de la adición de palmitato de ascorbilo (AP) durante la conservación del producto frito con especial atención a su efecto sinergista sobre los antioxidantes naturales. La evolución de la oxidación en lotes de patatas, con y sin adición de AP, se determinó mediante las siguientes determinaciones analíticas: índice de peróxidos (PV), cuantificación de tocoferoles y tocotrienoles, y periodos de inducción (IT) en Rancimat. La degradación de los aceites durante el proceso de fritura fue muy baja puesto que los niveles de compuestos polares y de antioxidantes naturales fueron similares a los encontrados en aceites refinados. La evolución de los índices analíticos durante el almacenamiento mostraron la importancia primordial del grado de insaturación del aceite por encima de la cantidad y tipo de antioxidantes y de la adición de AP. Sin embargo, la adición de AP a las patatas fritas tuvo un claro efecto sinergista traducido en menores PV y mayores cantidades de antioxidantes naturales e IT para cualquier tiempo de almacenamiento
A new tool based on artificial intelligence and GIS for preventive conservation of heritage buildings
This paper describes a new predictive model for preventive conservation of buildings. It allows for multiscenarios of several hazards, assessments of environmental risks, and the use level of buildings together with cultural val-ues of monuments. This modeling approach is based on fuzzy logic and geographic information system available to organizations dedicated to the restoration and rehabilitation in Spain. This system has a transversal development that includes urban, architectural, cultural heritage value, and the analysis of environmental and sociodemographic situations around the monuments. This new tool allows for decision making based on scientific criteria and minimizes risklosses of cultural asset
Shedding light on the methylerythritol phosphate (MEP)-pathway:long hypocotyl 5 (HY5)/phytochrome-interacting factors (PIFs) transcription factors modulating key limiting steps
The plastidial methylerythritol phosphate (MEP) pathway is an essential route for plants as the source of precursors for all plastidial isoprenoids, many of which are of medical and biotechnological importance. The MEP pathway is highly sensitive to environmental cues as many of these compounds are linked to photosynthesis and growth and light is one of the main regulatory factors. However, the mechanisms coordinating the MEP pathway with light cues are not fully understood. Here we demonstrate that by a differential direct transcriptional modulation, via the key-master integrators of light signal transduction HY5 and PIFs which target the genes that encode the rate-controlling DXS1, DXR and HDR enzymes, light imposes a direct, rapid and potentially multi-faceted response that leads to unique protein dynamics of this pathway, resulting in a significant difference in the protein levels. For DXS1, PIF1/HY5 act as a direct activation/suppression module. In contrast, DXR accumulation in response to light results from HY5 induction with minor contribution of de-repression by PIF1. Finally, HDR transcription increases in the light exclusively by suppression of the PIFs repression. This is an example of how light signaling components can differentially multi-target the initial steps of a pathway whose products branch downstream to all chloroplastic isoprenoids. These findings demonstrate the diversity and flexibility of light signaling components that optimize key biochemical pathways essential for plant growth. © 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Lt
Testing Eurasian wild boar piglets for serum antibodies against Mycobacterium bovis
A. Che’ Amat et al.Animal tuberculosis (TB) caused by infection with Mycobacterium bovis and closely related members of the M. tuberculosis complex (MTC), is often reported in the Eurasian wild boar (. Sus scrofa). Tests detecting antibodies against MTC antigens are valuable tools for TB monitoring and control in suids. However, only limited knowledge exists on serology test performance in 2-6 month-old piglets. In this age-class, recent infections might cause lower antibody levels and lower test sensitivity. We examined 126 wild boar piglets from a TB-endemic site using 6 antibody detection tests in order to assess test performance. Bacterial culture (. n=. 53) yielded a M. bovis infection prevalence of 33.9%, while serum antibody prevalence estimated by different tests ranged from 19% to 38%, reaching sensitivities between 15.4% and 46.2% for plate ELISAs and between 61.5% and 69.2% for rapid immunochromatographic tests based on dual path platform (DPP) technology. The Cohen kappa coefficient of agreement between DPP WTB (Wildlife TB) assay and culture results was moderate (0.45) and all other serological tests used had poor to fair agreements. This survey revealed the ability of several tests for detecting serum antibodies against the MTC antigens in 2-6 month-old naturally infected wild boar piglets. The best performance was demonstrated for DPP tests. The results confirmed our initial hypothesis of a lower sensitivity of serology for detecting M. bovis-infected piglets, as compared to older wild boar. Certain tests, notably the rapid animal-side tests, can contribute to TB control strategies by enabling the setup of test and cull schemes or improving pre-movement testing. However, sub-optimal test performance in piglets as compared to that in older wild boar should be taken into account.This is a contribution to Spanish Government MINECO Plan Nacional I+D+I grant AGL2014-56305 and FEDER, to a contract between CDTI and Glenton, and to the EU FP7 grant WildTBvac #613779. Azlan Che Amat has a PhD grant from the Malaysian Government, and José Angel Barasona and Iratxe Diéz-Delgado acknowledge PhD grants from the Spanish Government.Peer Reviewe
Laboratorio Remoto: Rejillas Periódicas Submicrométricas
We present the design of a remotely operated laboratory compatible with the requirements for setting a node at FaCENA within the R-LAB collaboration network coordinated by CONFEDI. We considered the antecedents on national and international experiences on running remote laboratories, definition of goals and pedagogical scope. We propose a prototype giving specifications on devices, measurement instruments and construction, operated through a modular versatile interface connected via web pages.Presentamos un diseño de laboratorio remoto compatible con los requerimientos para establecer un nodo FaCENA en la red R-LAB administrada por el CONFEDI. Consideramos los antecedentes sobre puesta en servicios de laboratorios remotos a nivel nacional e internacional; definiciones de metas y alcances pedagógicos; formulaciones del problema del diseño y la realización de una propuesta preliminar. Proponemos un prototipo con definiciones sobre dispositivos, instrumentos de medición, diseño y fabricación, mediante una interfaz del tipo modular muy versátil para conectividad vía páginas web
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