On the local existence of maximal slicings in spherically symmetric spacetimes

In this talk we show that any spherically symmetric spacetime admits locally a maximal spacelike slicing. The above condition is reduced to solve a decoupled system of first order quasi-linear partial differential equations. The solution may be accomplished analytical or numerically. We provide a general procedure to construct such maximal slicings.Comment: 4 pages. Accepted for publication in Journal of Physics: Conference Series, Proceedings of the Spanish Relativity Meeting ERE200

A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA

In this work we present ALMA continuum observations at 880 $\mu$m of 30 sub-mm cores previously identified with APEX/LABOCA at 870$\mu$m in the Barnard 30 cloud. The main goal is to characterize the youngest and lowest mass population in the cloud. As a result, we report the detection of five (out of 30) spatially unresolved sources with ALMA, with estimated masses between 0.9 and 67 M$_{\rm Jup}$. From these five sources, only two show gas emission. The analysis of multi-wavelength photometry from these two objects, namely B30-LB14 and B30-LB19, is consistent with one Class II- and one Class I low-mass stellar object, respectively. The gas emission is consistent with a rotating disk in the case of B30-LB14, and with an oblate rotating envelope with infall signatures in the case of LB19. The remaining three ALMA detections do not have infrared counterparts and can be classified as either deeply embedded objects or as starless cores if B30 members. In the former case, two of them (LB08 and LB31) show internal luminosity upper limits consistent with Very Low Luminosity objects, while we do not have enough information for LB10. In the starless core scenario, and taking into account the estimated masses from ALMA and the APEX/LABOCA cores, we estimate final masses for the central objects in the substellar domain, so they could be classified as pre-BD core candidates.Comment: Published in A&

Digestor anaeróbico enterrado asistido por energía solar térmica

Un digestor anaeróbico es un módulo capaz de entregar una mezcla de gases como metano y dióxido de carbono llamado biogás. Este debe ser cargado con material orgánico que se degrada bajo condiciones de temperatura constante y en ausencia total de oxígeno. La aclimatación de un digestor anaeróbico requiere de temperaturas de entre 25° C y 45° C en el rango mesofílico. En este trabajo se propone la incorporación de un colector solar con este fin. El colector solar no posee cubierta transparente y está construido casi en su mayoría con material plástico de PVC. Posee alta capacidad de acumulación y sus dimensiones son: 0,80 metros de ancho por 2,20 metros de largo. Este se integra a un digestor anaeróbico enterrado de 1000 litros de capacidad llenado en un 40% de su volumen. Se mantiene al digestor a una temperatura constante de 30° C por tanto se cuenta con un sistema de calefacción eléctrico capaz de asistir en los momentos en que no se cuente con la radiación solar. Con el sistema de calentamiento propuesto se logró lo cometido, la temperatura se mantuvo estable con pequeñas oscilaciones que el digestor en operación puede soportar sin interrupciones de la producción normal de biogás. La aplicación del colector depende mucho de las condiciones de radiación solar dada por el lugar en donde se encuentre instalado. En la Ciudad de Salta se logra una ventaja mayor que en otras regiones del país ya que posee un clima seco de alta radiación solar en la estación invernal. Se expone en este trabajo los resultados de las medidas de temperatura tomadas en el colector solar y el digestor anaeróbico. También se evalúa la curva de eficiencia del colector.Facultad de Ingenierí

Experimental Type 2 Diabetes Induces Enzymatic Changes in Isolated Rat Enterocytes

Diabetes in humans and in experimental animals produces changes in the function and structure of the small intestine. The authors determined the activity of intestinal disaccharidases (maltase and sucrase) and of 6-phosphofructo-1-kinase (PFK-1) in enterocytes isolated from the small intestine of male Wistar rats (2.5 to 3 months old) with experimental nonobese type 2 diabetes, induced by streptozotocin (STZ) injection on the day of birth (n0-STZ) or on the 5th day of life (n5-STZ), with different degrees of hyperglycemia and insulinemia (n0-STZ and n5-STZ models). The glycemia (mmol/L) of the diabetic rats (n0-STZ: 8.77 ± 0.47; n5-STZ: 20.83 ± 0.63) was higher (P < .01) than that of the nondiabetic (ND) rats (5.99 ± 0.63); on the contrary, the insulinemia (ng/mL) was significantly lower in both n0-STZ (1.74 ± 0.53; P < .05) and n5-STZ (1.12 ± 0.44; P < .01) diabetic rats than in normal rats (3.77 ± 0.22). The sucrase and maltase activities (U/g protein) in diabetic rats (n0-STZ: 89 ± 9 and 266 ± 12; n5-STZ: 142 ± 23 and 451 ± 57) were significantly higher than those in the ND group (66 ± 5 and 228 ± 22). The PFK-1 activities (mU/mg protein) in the diabetic models (n0-STZ: 14.89 ± 1.51; n5-STZ: 13.35 ± 3.12) were significantly lower (P < .05) than in ND rats (20.54 ± 2.83). The data demonstrated enzymatic alterations in enterocytes isolated fromthe small intestine of n0-STZ rats that are greater (P < .05) than in the more hyperglycemic and hypoinsulinemic n5-STZ animals. The results also show that nonobese type 2–like diabetes in the rat produces modifications that favor an increase in glucose absorption rates

On Some Sampling-Related Frames in U-Invariant Spaces

This paper is concerned with the characterization as frames of some sequences in -invariant spaces of a separable Hilbert space H where U denotes an unitary operator defined on H ; besides, the dual frames having the same form are also found. This general setting includes, in particular, shift-invariant or modulation-invariant subspaces in L2(R) , where these frames are intimately related to the generalized sampling problem. We also deal with some related perturbation problems. In doing so, we need the unitary operator to belong to a continuous group of unitary operators

Relación entre la presencia de Malassezia Pachydermatis y los signos clínicos encontrados en cuadros de otitis crónicas caninas en una población de perros de raza Podenco canarios

El papel que desempeña Malassezia pachydermatis como factor perpetuante en las otitis externas caninas ha sido muy discutido. Dada la problemática que presentan las otitis en la clínica veterinaria, hemos intentado determinar la relación existente entre las manifestaciones clínicas de otitis externas crónicas caninas, y la presencia de esta levadura en los oídos de perros de raza Podenco canario. A los perros se les realizó una exploración física general, toma de muestras de ambos conductos auditivos externos, video otoscopia, y toma de biopsias de dichos conductos. Se realizó un contaje de M. pachydermatis por campo en cada una de las muestras a mil aumentos, y con objetivo de inmersión. Los resultados citológicos fueron comparados con los obtenidos de los cultivos en placa, los signos y lesiones encontrados en la exploración y con los hallados en las biopsias. Más de la mitad dé los perros estudiados padecían otitis crónica, siendo la forma eritematosa-ceruminosa la más comúnmente diagnosticada. Se aisló M. pachydermatis en el 54'28% de los conductos auditivos externos(CAE) con signos clínicos o lesiones. Como conclusión, comprobamos que el contaje por campos de esta levadura a mil aumentos en los frotis de las muestras, es un método bastante fiable para determinar el papel patógeno de M. pachydermatis en los cuadros de otitis crónicas caninas, y para decidir si instaurar o no un tratamiento antifúngica frente a las mismas a la espera de pruebas diagnósticas más concluyentes

Effect of the milk-whey relation over physicochemical and rheological properties on a fermented milky drink

(Eng) The effect of the milk-whey relation over the physicochemical properties (pH, total acidity, soluble solids and syneresis) and rheology (deformation rate, apparent viscosity, flow behavior index and consistency index) of a fermented dairy drink was studied. A completely randomized experimental design of two factors: percentage of whey (0, 5, 10 and 15% w/w) and type of milk (whole and skim) was used. The significance was determined using an analysis of variance (ANOVA). All properties analyzed except pH had statistically significant differences (P<0.05). The use of whole milk in comparison to skim milk generated an increase in soluble solids and viscosity of the beverage but caused a decrease in acidity and syneresis. The growth in whey concentration increased syneresis and apparent viscosity but decreased soluble solids and consistency index. The changes in properties are related to the contribution of fat from milk and the contribution of calcium and phosphate from whey, affecting both the interaction between the casein micelles and the water retention capacity, which changes the composition and fluidity of the beverage.(Spa) Se estudió el efecto de la relación leche-lactosuero sobre las propiedades fisicoquímicas (pH, acidez total, sólidos solubles y sinéresis) y reológicas (velocidad de deformación, viscosidad aparente, índice de comportamiento al flujo e índice de consistencia) de una bebida láctea fermentada. Se utilizó un diseño experimental completamente al azar de dos factores: porcentaje de lactosuero (0, 5, 10 y 15% p/p) y tipo de leche (entera y descremada). La significancia se determinó mediante un análisis de varianza (ANOVA). Todas las propiedades analizadas excepto el pH presentaron diferencias estadísticamente significativas (P<0,05). El uso de la leche entera en comparación con la leche descremada generó un incremento en los sólidos solubles y en la viscosidad de la bebida, pero causó una disminución en la acidez y la sinéresis. El incremento en la concentración de lactosuero aumentó la sinéresis y la viscosidad aparente pero disminuyó los sólidos solubles e índice de consistencia. Los cambios en las propiedades se relacionan con el aporte de grasa que realiza el tipo de leche y la contribución de calcio y fosfato que efectúa la adición de lactosuero, afectando tanto la interacción entre las micelas de caseína como la capacidad de retención de agua, que resulta en cambios en la composición y fluidez de la bebida

Two-dimensional distributed feedback lasers with thermally-nanoimprinted perylenediimide-containing films

Two-dimensional (2D) distributed feedback (DFB) lasers with gratings imprinted by thermal nanoimprint lithography on the active film are reported. They show thresholds for lasing of ∼10 kW/cm2, similar to the most efficient imprinted DFB lasers reported; and long operational lifetimes (under ambient conditions) of ∼12 × 104 pump pulses. The key for their successful operation has been the selection of a highly efficient and stable dye, perylene orange (PDI-O), and a proper matrix to host it, the fluoro-modified thermoplastic resist mr-I7030R, which has enabled 2D imprinting while preserving the dye optical properties. The use of the UV-curable resist SU8 as an alternative matrix for PDI-O to be imprinted by combined nanoimprint and photolithography was also investigated, and was concluded to be unsuccessful due to severe photoluminescence quenching. By replacing PDI-O with Rhodamine 6G, lasers with reasonable thresholds, but with significantly inferior operational lifetimes in comparison to PDI-O/mr-I7030R devices, were obtained.We thank support from the Spanish Government (MINECO) and the European Community (FEDER) through Grants MAT2011-28167-C02 and MAT2015-66586-R, as well as to the University of Alicante. M.M-V. has been partly supported by a MINECO FPI fellowship (no. BES-2009-020747) and by a Junta de Castilla y León grant (no. SA046U16)

Distributed feedback lasers based on perylenediimide dyes for label-free refractive index sensing

The refractive index sensing capabilitity of distributed feedback (DFB) lasers based on highly photostable (under ambient conditions) perylenediimide-based active films, are reported. The sensor bulk sensitivity is determined from changes in the laser emission wavelength upon exposure to different liquids. The role of the active film thickness (hf) on the sensor sensitivity and on the laser parameters is studied. Sensors based on very thin films (hf = 160 nm) show the highest sensitivities, but their laser thresholds are relatively high and their operational durabilities moderate. The use of thicker films (hf = 850 nm) allows reducing the laser threshold and increasing the durability by two orders of magnitude. In this case, a higher sensitivity is achieved when the sensor operates at the wavelength corresponding to the first-order TE1 mode, instead of at the TE0 one. Finally, it is also shown that the inclusion of a high refractive index TiO2 layer on top of the sensor structure improves the sensitivity by around two times.This work was supported by the Spanish Government (MINECO) and the European Community (FEDER) through grant no. MAT-2011–28167-C02. This work was partially funded by the Basque Government within the framework of the Etortek Program (Grant No. IE13-360). M. Morales-Vidal has been partly supported by a MINECO FPI fellowship (no. BES-2009-020747)