Avalanches in Critical Activated Random Walks

We consider Activated Random Walks on $\Z$ with totally asymmetric jumps and critical particle density, with different time scales for the progressive release of particles and the dissipation dynamics. We show that the cumulative flow of particles through the origin rescales to a pure-jump self-similar process which we describe explicitly

Can rigidly rotating polytropes be sources of the Kerr metric?

We use a recent result by Cabezas et al. to build up an approximate solution to the gravitational field created by a rigidly rotating polytrope. We solve the linearized Einstein equations inside and outside the surface of zero pressure including second-order corrections due to rotational motion to get an asymptotically flat metric in a global harmonic coordinate system. We prove that if the metric and their first derivatives are continuous on the matching surface up to this order of approximation, the multipole moments of this metric cannot be fitted to those of the Kerr metric.Comment: LaTeX, 17 pages, submitted to CQ

Semiclassical Nonlinear Approach for Mesoscopic Circuit

Based on energy conservation considerations we study the nonlinear dynamic behavior of a quantum mesoscopic circuit, which is characterized through parameters of inductance and capacitance. Nonlinearity is given by the initial conditions of magnetic flux and discreteness charge which oscillate in the interval [- , + ], being the magnetic flux normalized by . This LC circuit with quantized electric charge is excited by energy battery that can produce an electrical discreteness charge on the capacitor. The dynamics of the mesoscopic circuit is highly nonlinear. Our results show for the magnetic flux a nearly square wave with an elongated period when compared with the linear case and a train of narrow pulses for the discrete charge

A Seismic Channel Model: The San Ramon Fault

Although seismic waves have been studied for many years, their soliton structure has only recently studied. Deformation solitons propagate along earthquake faults and can induce large earthquakes. Rotation solitons are generated in earthquake sources and propagate throughout the Earth. The conclusion to be reached from our paper is that the research on seismic solitons is essential for investigating the propagation of seismic waves and helps understand mechanisms triggering earthquakes. This paper discusses the development of elastodynamics equations similar to Maxwell's equations in a chiral -mode which is applied to a seismic channel, which is dispersive and nonlinear. The chirality is described in terms of the formalism proposed by Born-Fedorov. The nonlinearity is Kerr-type, and dispersion of the medium is taken into account explicitly through the Taylor series expansion. Through numerical calculations these theoretical results allow us analyze the soliton propagation of S-seismic pulses which can induce strong earthquakes. The numerical calculation is applied to the San Ramon Fault localized in Santiago City, Chile which is a seismically active fault that is a main element to be considered in any study on seismic hazard assessment for this city

Diazoxide-responsive hyperinsulinemic hypoglycemia caused by HNF4A gene mutations

Objective: The phenotype associated with heterozygous HNF4A gene mutations has recently been extended to include diazoxide responsive neonatal hypoglycemia in addition to maturity-onset diabetes of the young (MODY). To date, mutation screening has been limited to patients with a family history consistent with MODY. In this study, we investigated the prevalence of HNF4A mutations in a large cohort of patients with diazoxide responsive hyperinsulinemic hypoglycemia (HH). Subjects and methods: We sequenced the ABCC8, KCNJ11, GCK, GLUD1, and/or HNF4A genes in 220 patients with HH responsive to diazoxide. The order of genetic testing was dependent upon the clinical phenotype. Results: A genetic diagnosis was possible for 59/220 (27%) patients. KATP channel mutations were most common (15%) followed by GLUD1 mutations causing hyperinsulinism with hyperammonemia (5.9%), and HNF4A mutations (5%). Seven of the 11 probands with a heterozygous HNF4A mutation did not have a parent affected with diabetes, and four de novo mutations were confirmed. These patients were diagnosed with HI within the first week of life (median age 1 day), and they had increased birth weight (median +2.4 SDS). The duration of diazoxide treatment ranged from 3 months to ongoing at 8 years. Conclusions: In this large series, HNF4A mutations are the third most common cause of diazoxide responsive HH. We recommend that HNF4A sequencing is considered in all patients with diazoxide responsive HH diagnosed in the first week of life irrespective of a family history of diabetes, once KATP channel mutations have been excluded

Sintering and mechanical properties of cemented carbides based on tungsten carbide and multicomponent metallic alloys.

Cemented carbides are composite materials used in a wide variety of applications requiring the right combination of mechanical strength and wear resistance under harsh environments (i.e. metal cutting and shaping, civil engineering, mining, valves for the chemical industry, etc). The most common compositions comprise tungsten carbide grains bonded with a cobalt based metallic matrix. The reason is twofold. On the one hand, WC-Co materials are relatively easy to sinter to full density state with the adequate processing methodology and, on the other, a wide range of useful properties can be obtained by changing the WC grain size and the WC/Co ratio. Nevertheless, the use and availability of cobalt are presently jeopardized by both its new classification as toxic substance (REACH regulations) and the growing demand of this metal for making Li-ion batteries for electrical vehicles. The present thesis is focused on studying the sintering behavior and mechanical properties of WC-metal systems in which pure cobalt is replaced by different combinations of metals. Two promising candidates have been found: WC-NiCoCrTiAl cemented carbides These materials were designed starting from WC-NiCoCr compositions with a Ni/Co ratio equal to one. The main challenge was to increase the hardness of these compositions since it is too low compared with that of WC-Co grades. This was achieved firstly by alloying the binder phase with aluminum and, afterwards, inducing gamma prime precipitation by aging treatments. Two different aluminum containing compounds were investigated in order to avoid catastrophic oxidation of aluminum during PM processing: AlN and TiAl3. The latter produced the best results concerning sinterability and precipitation hardening effects. WC-Ni-Co-Cr-Ti-Al materials were obtained in fully dense form by using HIP after sintering technique, a process compatible with industrial processing technologies like Sinter HIP. Aging experiments show that hardness peaks occur at lower temperatures as the Al content of the binder phase increases. Apart from hardness, transverse rupture strength (TRS) was also measured in selected WC-NiCoCrTiAl compositions in both as-HIPed and solution-aged conditions. Results are only 15% lower than those reported for WC-Co materials with similar WC grain sizes and WC/metal ratios. These results also suggest that, like in as-cast Ni superalloys, the properties of the binder phase would be retained at temperatures below those used in aging treatments. WC-FeNiCoCr cemented carbides WC-Fe-Ni-Co-Cr compositions were designed following an alternative approach. In this case, the aim was to obtain a metallic binder with no precipitation of free carbon or any secondary carbide (including those of chromium). This was achieved by starting from WC-Fe-Ni-Co-Cr3C2 powder mixtures with a constant proportion between Fe, Ni and Co equal to 40/40/20. Chromium and carbon contents have been modified in order to find the upper and lower bounds defining the “so-called” carbon windows. In addition, shrinkage kinetics have been thoroughly studied in order to define a robust sintering process for both coarse and submicron WC powders. Results of calorimetric experiments have been used to improve the description of the W-C-Fe-Ni-Co quinary system for 40Fe-40Ni-20Co composition by means of ThermoCalc® software. In this case, mechanical tests confirmed that the values of hardness and transverse rupture strength are within tolerances of those reported for WC-Co grades with similar binder contents and WC grain sizes, provided that precipitation of undesired phases is avoided.Los carburos cementados son materiales compuestos utilizados en una amplia variedad de aplicaciones que requieren la combinación correcta de resistencia mecánica y resistencia al desgaste en entornos hostiles (es decir, corte y conformado de metales, ingeniería civil, minería, válvulas para la industria química, etc). Las composiciones más comunes comprenden granos de carburo de tungsteno unidos con una matriz metálica de cobalto. La razón es doble. Por un lado, los materiales WC-Co son relativamente fáciles de sinterizar a un estado de densidad completa con la metodología de procesamiento adecuada y, por otro lado, una amplia variedad de propiedades útiles se pueden obtener variando el tamaño de grano de WC y la relación WC/Co. Sin embargo, el uso y la disponibilidad de cobalto está actualmente en peligro tanto por su nueva clasificación como sustancia tóxica (normativa REACH) como por la creciente demanda de este metal para la fabricación de baterías de iones de litio para vehículos eléctricos. La presente tesis se centra en el estudio de la sinterización y las propiedades mecánicas de sistemas WC-metal en los que el cobalto puro es reemplazado por diferentes combinaciones de metales. Se han encontrado dos candidatos prometedores: Carburos cementados WC-NiCoCrTiAl Estos materiales fueron diseñados a partir de composiciones WC-NiCoCr con una relación Ni/Co igual a uno. El principal reto fue aumentar la dureza de estas composiciones ya que es muy baja en comparación con los grados WC-Co. Esto se logró en primer lugar mediante la aleación de la fase ligante con aluminio y, posteriormente, induciendo la precipitación gamma prima mediante tratamientos de envejecimiento. Se investigaron dos fuentes de aluminio distintas para evitar una oxidación catastrófica del aluminio durante el procesamiento PM: AlN y TiAl3. Este último produjo los mejores resultados en cuanto a la sinterabilidad y los efectos de endurecimiento por precipitación. Los materiales WC-Ni-Co-Cr-Ti-Al fueron obtenidos en forma totalmente densa mediante el uso de HIP después de la sinterización, un proceso compatible con tecnologías de procesamiento industrial como Sinter HIP. Los experimentos de envejecimiento muestran que la dureza alcanza su punto máximo a temperaturas más bajas a medida que aumenta el contenido de Al de la fase ligante.Además de la dureza, la resistencia a la ruptura transversal (TRS) también se midió en composiciones seleccionadas de WC-NiCoCrTiAl tanto en condiciones de HIPed como de envejecimiento en solución. Los resultados son solo el 15% más bajos que los reportados para materiales WC-Co con tamaños de grano de WC y proporciones WC/metal similares. Estos resultados sugieren también que, al igual que en las superaleaciones base Ni, las propiedades de la fase ligante se mantendrían a temperaturas inferiores a las utilizadas en los tratamientos de envejecimiento. Carburos cementados WC-FeNiCoCr Las composiciones WC-Fe-Ni-Co-Cr fueron diseñadas siguiendo un enfoque alternativo. En este caso, el objetivo era obtener un ligante metálico sin precipitación de carbono libre ni ningún carburo secundario (incluidos los de cromo). Esto se logró partiendo de mezclas en polvo WC- Fe-Ni-Co-Cr3C2 con una proporción constante entre Fe, Ni y Co igual a 40/40/20. Los contenidos en cromo y carbono han sido modificados para encontrar los límites superior e inferior que definen "las llamadas" ventanas de carbono. Además, la cinética de contracción se ha estudiado a fondo para definir un proceso robusto de sinterización para polvos de WC gruesos y submicra. Los resultados de los experimentos calorimétricos se han utilizado para mejorar la descripción del sistema quinario W-C-Fe-Ni-Co para la composición 40Fe-40Ni-20Co mediante el software ThermoCalc®. En este caso, las pruebas mecánicas confirmaron que los valores de dureza y de resistencia a la ruptura transversal están dentro de las tolerancias reportadas para los grados WC-Co con contenidos de ligante y tamaños de grano de WC similares, siempre que se evite la precipitación de fases no deseadas

Morphological and Molecular Characterization of Grapevine Accessions Known as Albillo

Twenty-eight accessions identified under the name of Albillo or cited as a synonym of this ancient Spanish grapevine variety were characterized using 43 morphological descriptors, four different isozyme systems (CO, ACPH, GOT, and SOD) and two Amplified Fragment Length Polymorphism (AFLP) primer combinations. Genetic similarity data resulting from these analyses allowed three different groups of Albillo to be distinguished that corresponded with geographical and historical origin of representative varieties: Turruntés, Malvasía de El Bierzo, and the classical Albillo de Madrid, related to the oldest Albillo ampelographical descriptions. In addition, homonyms as well as varieties incorrectly cited as Albillo synonyms were identified. To ensure accurate variety identification, association among historical descriptions based on morphological descriptors and molecular fingerprints was required. Isozymes proved to be useful markers for varietal identification. However, only AFLP allowed distinction among closely related varieties as well as the analysis of intravarietal variation.M.T.C. was funded by a Ministerio de Educación y Cultura contract; I.R., J.A.C., and J.C. were funded by predoctoral fellowships from the European Union, Instituto Nacional de Investigaciones Agrarias y Agroalimentarias, and Agencia Española de Cooperación Internacional, respectively. This research was funded in part by projects INIA SC96-010, SC94-092, and CM 07B-0010-1997. Support for research activity at the Centro Nacional de Biotecnología is provided by a CSIC-INIA specific agreement.Peer reviewe

Suplementación de raciones para cebo intensivo de terneros con aceites vegetales: rendimientos productivos, calidad de la canal, de la grasa y de la carne

Se han estudiado los efectos de la incorporación de aceites de origen vegetal sobre los rendimientos productivos, calidad de la canal y de la grasa en el ganado vacuno. Se utilizaron 240 terneros agrupados en 24 lotes de 10 terneros cada uno. Las raciones experimentales fueron: Tratamiento Control (4% de aceite de palma), Oliva (4,8% de jabón cálcico de aceite de oliva), Soja (4% de aceite de soja). De cada lote se seleccionó al azar un ternero (8 terneros por tratamiento) para diseccionar su 6ª costilla. No se han observado diferencias significativas entre tratamientos para ningún parámetro productivo ni de calidad de la canal. Los animales que consumieron aceite de oliva presentaron un mayor contenido (P=0,09) en C18:2 cis-9, trans-11 CLA en la grasa intramuscular que los que consumieron palma