Physical interpretation of the Mullins softening in a carbon-black filled SBR

A 40 phr carbon-black filled styrene butadiene rubber has been submitted to several experiments in order to identify the physical damage responsible for the mechanical softening recorded upon first stretch. Damage in the rubber matrix was determined by swelling. The filler structure alteration was monitored by electrical conductivity measurements. Both damages are shown to be of minor importance compared to the substantial mechanical softening undergone by the material. Degradation at the rubber-filler interface may be recovered by exposing the material at high temperatures in vacuo. The chain mobility in such storage conditions promotes free chain adsorption at the filler surface. The existence of a layer of polymer whose movements are hindered adds to the filler reinforcement and its desorption creates Mullins softening

Midiendo retornos accionarios en el mercado de capitales Brasileno : El enfoque de simulacion de Brown y Warner

39 p.Los estudios de eventos buscan estimar el efecto que tiene un determinado evento sobre el valor de la firma, es decir, cuantificar el efecto de un evento sobre el precio de mercado de las acciones que componen el patrimonio de la empresa. Considerando que el poder de este método ha sido escasamente validada para el caso de mercados de capitales emergentes, en el presente trabajo se utiliza el enfoque de simulación de Brown y Warner y usando retornos diarios del mercado accionario brasileño, se examina la especificación y el poder de tres estadísticos comúnmente utilizados en estudios de evento: el test estandarizado, el de corte transversal y el de portafolio. Se analizaron 250 muestras formadas a partir de una muestra de acciones de empresas brasileñas obtenidas de la Bolsa de Valores de Sao Paulo. Por medio del software EventusPro se simula el efecto que tiene un hecho económico sobre el rendimiento de los activos que componen dichas muestras. Con este procedimiento es posible analizar el poder de tests estadísticos para diferentes niveles de retorno anormal introducidos artificialmente. Los resultados indican que aunque existen síntomas de no-normalidad en los retornos y excesos de retornos persistentes aún a nivel de portafolio, métodos basados en el use de tests paramétricos y muestras de 10 o mas activos se encuentran bien especificados, al menos para un nivel de significancia del 5%. En términos del poder del test, el test estandarizado parece siempre ser mas eficaz en la captura de un retorno anormal que sus dos competidores: el de corte transversal y el de portafolio. También se observa, sin embargo, que el poder de las tres pruebas estadísticas analizadas es muy sensible al tamaño muestral

Transient lateral photovoltaic effect in patterned metal-oxide-semiconductor films

The time dependent transient lateral photovoltaic effect has been studied with us time resolution and with chopping frequencies in the kHz range, in lithographically patterned 21 nm thick, 5, 10 and 20 um wide and 1500 um long Co lines grown over naturally passivated p-type Si (100). We have observed a nearly linear dependence of the transitorial response with the laser spot position. A transitorial response with a sign change in the laser-off stage has been corroborated by numerical simulations. A qualitative explanation suggests a modification of the drift-diffusion model by including the in uence of a local inductance. Our findings indicate that the microstructuring of position sensitive detectors could improve their space-time resolution.Comment: 4 pages, 4 figure

Interactive Neural Resonators

In this work, we propose a method for the controllable synthesis of real-time contact sounds using neural resonators. Previous works have used physically inspired statistical methods and physical modelling for object materials and excitation signals. Our method incorporates differentiable second-order resonators and estimates their coefficients using a neural network that is conditioned on physical parameters. This allows for interactive dynamic control and the generation of novel sounds in an intuitive manner. We demonstrate the practical implementation of our method and explore its potential creative applications

The Warburg and Crabtree effects: On the origin of cancer cell energy metabolism and of yeast glucose repression

AbstractDuring the last decades a considerable amount of research has been focused on cancer. Recently, tumor cell metabolism has been considered as a possible target for cancer therapy. It is widely accepted that tumors display enhanced glycolytic activity and impaired oxidative phosphorylation (Warburg effect). Therefore, it seems reasonable that disruption of glycolysis might be a promising candidate for specific anti-cancer therapy. Nevertheless, the concept of aerobic glycolysis as the paradigm of tumor cell metabolism has been challenged, as some tumor cells exhibit high rates of oxidative phosphorylation. Mitochondrial physiology in cancer cells is linked to the Warburg effect. Besides, its central role in apoptosis makes this organelle a promising “dual hit target” to selectively eliminate tumor cells. From a metabolic point of view, the fermenting yeast Saccharomyces cerevisiae and tumor cells share several features. In this paper we will review these common metabolic properties as well as the possible origins of the Crabtree and Warburg effects. This article is part of a Special Issue entitled: Bioenergetics of Cancer

Hierarchical spatial structure and levels of resolution of intertidal grazing and their consequences on predictability and stability at small scales

The aim of this research was to assess three hierarchical aspects of alga-grazer interactions in intertidal communities on a small scale: spatial heterogeneity, grazing effects and spatial stability in grazing effects. First, using semivariograms and cross-semivariograms I observed hierarchical spatial patterns in most algal groups and in grazers. However, these patterns varied with the level on the shore and between shores, suggesting that either human exploitation or wave exposure can be a source of variability. Second, grazing effects were studied using manipulative experiments at different levels on the shore. These revealed significant effects of grazing on the low shore and in tidal pools. Additionally, using a transect of grazer exclusions across the shore, I observed unexpected hierarchical patchiness in the strength of grazing, rather than zonation in its effects. This patchiness varied in time due to different biotic and abiotic factors. In a separate experiment, the effect of mesograzers effects were studied in the upper eulittoral zone under four conditions: burnt open rock (BOR), burnt pools (Bpool), non-burnt open rock (NBOR) and non-burnt pools (NBpool). Additionally, I tested spatial stability in the effects of grazing in consecutive years, using the same plots. I observed great spatial variability in the effects of grazing, but this variability was spatially stable in Bpools and NBOR, meaning deterministic and significant grazing effects in consecutive years on the same plots. Both the significance in grazing effects and spatial stability depended on the level of resolution (species, functional, biomass) at which the algal assemblage was evaluated, suggesting hierarchical variability. In order to be able to predict spatial variability in the effects of grazers in the upper eulittoral zone using biotic and abiotic micro- and macrofactors, a conceptual model was proposed, based on data from several multiple-regressions. This linked the interactions among three elements: idiosyncratic heterogeneity, micro and macrofactors. This suggests that spatial variability can be a product of these factors, while spatial stability can be caused by the same or different combinations of factors. In conclusion, grazing and other ecological phenomena must be studied hierarchically, not only through spatiotemporal scales, but also at different levels of resolution, as these also influence our perception of patterns

Temperature-dependent development of the cycad aulacaspis scale, aulacaspis yasumatsui (Hemiptera: Diaspididae)

Egg duration period, immature development time, and pre-oviposition period of the cycad aulacaspis scale, Aulacaspis yasumatsui Takagi, were measured at 9 constant temperatures in the laboratory. Egg duration period ranged from 15 d at 20°C to 7 d at 30°C. First instar development time was 30 d at 18°C but only 4 d at 35°C. No first instars completed development below 18°C or above 35°C. Development time of second instar females ranged from 19 d at 18 and 20°C to 9 d at 30°C. Development time of male second instar + pupa ranged from 15 d at 20°C to 910 d at 2532°C. Pre-oviposition period averaged 14 d at 20°C to 8 d at 25 32°C; no females laid eggs at 18 and 35°C. The lowest temperature threshold for all stages ranged from 8 to 12°C and 538 degree-days were required for female immature development in a linear model. Development rates of the scale are compared to those of 3 of its natural enemies, Cybocephalus nipponicus Endrdy-Younga, Rhyzobius lophanthae (Blaisdell), and Coccobius fulvus (Compere and Annecke)

GJMS-like operators on symmetric 2-tensors and their gravitational duals

We study a family of higher-derivative conformal operators $P_{2k}^{(2)}$ acting on transverse-traceless symmetric 2-tensors on generic Einstein spaces. They are a natural generalization of the well-known construction for scalars. We first provide the alternative description in terms of a bulk Poincar\'e-Einstein metric by making use of the AdS/CFT dictionary and argue that their holographic dual generically consists of bulk massive gravitons. At one-loop quantum level, we put forward a holographic formula for the functional determinant of the higher-derivative conformal operators $P_{2k}^{(2)}$ in terms of the functional determinant for massive gravitons with standard and alternate boundary conditions. The analogous construction for vectors $P_{2k}^{(1)}$ is worked out as well and we also rewrite the holographic formula for unconstrained vector and traceless symmetric 2-tensor by decoupling the longitudinal part. Finally, we show that the holographic formula provides the necessary building blocks to address the massless and partially massless bulk gravitons. This is confirmed in four and six dimensions, verifying full agreement with results available in the literature.Comment: 15 Pages, 0 figures. Minor change

Symmetries of first-order Lovelock gravity

We apply the converse of Noether’s second theorem to the first-order n-dimensional Lovelock action, considering the frame rotation group as both SO (1, n − 1) or as SO(n). As a result, we get the well-known invariance under local Lorentz transformations or SO(n) transformations and diffeomorphisms, for odd- and even-dimensional manifolds. We also obtain the so-called ‘local translations’ with nonvanishing constant Λ for odd-dimensional manifolds when a certain relation among the coefficients of the various terms of the first-order Lovelock Lagrangian is satisfied. When this relation is fulfilled, we report the existence of a new gauge symmetry emerging from a Noether identity. In this case the fundamental set of gauge symmetries of the Lovelock action is composed by the new symmetry, local translations with Λ ≠ 0 and local Lorentz transformations or SO(n) transformations. The commutator algebra of this set closes with structure functions. We also get the invariance under local translations with Λ = 0 of the highest term of the Lovelock action in odd-dimensional manifolds. Furthermore, we report a new gauge symmetry for the highest term of the first-order Lovelock action for odd-dimensional manifolds. In this last case, the fundamental set of gauge symmetries can be considered as Poincaré or Euclidean transformations together with the new symmetry. The commutator algebra of this set also closes with structure functions