Growing interfaces in quenched disordered media

We present the microscopic equation of growing interface with quenched noise for the Tang and Leschhorn model [{\em Phys. Rev.} {\bf A 45}, R8309 (1992)]. The evolution equations for the mean heigth and the roughness are reached in a simple way. Also, an equation for the interface activity density (i.e. interface density of free sites) as function of time is obtained. The microscopic equation allows us to express these equations in two contributions: the diffusion and the substratum one. All the equation shows the strong interplay between both contributions in the dynamics. A macroscopic evolution equation for the roughness is presented for this model for the critical pressure $p=0.461$. The dynamical exponent $\beta=0.629$ is analitically obtained in a simple way. Theoretical results are in excellent agreement with the Monte Carlo simulation.Comment: 6 pages and 3 figures. Conference on Percolation and disordered systems: theory and applications, Giessen, Germany, (July, 1998

Phenomenology of the SU(3)_c X SU(3)_L X U(1)_X model with right-handed neutrinos

A phenomenological analysis of the three-family local gauge group $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ with right-handed neutrinos is carried out. Instead of using the minimal scalar sector able to break the symmetry in a proper way, we introduce an alternative set of four Higgs scalar triplets, which combined with an anomaly-free discrete symmetry, produces a quark mass spectrum without hierarchies in the Yukawa coupling contants. We also embed the structure into a simple gauge group and show some conditions to achieve a low energy gauge coupling unification, avoiding possible conflict with proton decay bounds. By using experimental results from the CERN-LEP, SLAC linear collider and atomic parity violation data, we update constraints on several parameters of the model.Comment: RevTeX, 10 pages, 4 figures. v2: 13 pages. Substantial changes. New section about RGE analysis. Experimental data updated. v3: Discussions about bounds from unitarity violation of the CKM matrix and from FCNC included. Accepted for publication in Eur. Phys. J.

XAS study of the local environment of impurities in doped TiO2 thin films

In this work we present an X-ray Absorption Spectroscopy characterization of the local environment of the impurity in room temperature ferromagnetic anatase TiO2 thin films doped with Co, Ni, Cu, or Zn, deposited on LaAlO3 substrate by Pulsed Laser Deposition. It was found that there is a considerable amount of impurity atoms substituting Ti in TiO2 anatase, although the presence of metal transition monoxide clusters can not be discarded. From our results we infer that the observed room temperature ferromagnetism of the samples could be assigned to the metal transition atoms replacing Ti in TiO2 anatase.Comment: 4 pages, 3 figures, 1 table, Physica B (in press

Photosynthetic and leaf anatomical characteristics of Castanea sativa: A comparison between in vitro and nursery plants

The anatomic and functional leaf characteristics related to photosynthetic performance of Castanea sativa growing in vitro and in nursery were compared. The irradiance saturated photosynthesis in in vitro grown plantlets was significantly lower compared to nursery plants (65 vs. 722 μmol m

Dynamic Evaluation of Production Policies: Improving the Coordination of an Ethanol Supply Chain

AbstractThis paper uses System Dynamics modeling and process simulation to explore coordination in two logistic processes (procurement and production) of the supply chain of an ethanol plant. In that sense, three production scenarios are evaluated to identify: a) stock movement according to current inventory policies, and b) the critical variables affecting the coordination for these two processes. Since the main goal in the company is to meet customer demand, this research incorporates sales forecasting, and four performance indicators to evaluate the state of the processes: 1) average percentage of demand satisfaction, 2) maximum amount of ethanol in excess, 3) available ethanol at the end of the year, and 4) inventory costs. To model the case study, the change in production yield and specific constraints for the chain are considered. The simulation results show that System Dynamics modeling can be used to observe the effects of policies on inventory, and meeting the demand in a real system. It also can define the coordination for a supply chain and give information to improve it. The developed model uses STELLA® software to simulate the logistic processes and execute the evaluation employing the performance indicators

Dynamic changes in the lower Gállego River (Ebro Basin, NE Spain) and their relationship with anthropic activities and the quaternary substrate

The lower Gállego River has been strongly degraded since the 1960s due to human activity (gravel mining, dump accumulation, channeling works), which has produced a deep channel incision. Although these humandriven processes are usually reported in fluvial bibliography, in this case, more complex results are observable. For instance, regarding the depth and incision rates, we observed no relationship between the most anthropically impacted areas and the sections with the deepest incisions; moreover, the deepening process continues 40 years after the human interventions ceased. The reason for this maladjustment is the role played by the exhumation of the underlying Pleistocene substrate, affected by the synsedimentary processes of karstification. The appearance of paleodolines filled with fine sediments on the incision bottom and sides is the main factor conditioning the continuity and magnitude of the process. Besides, these paleodepressions direct the river dynamics and course, thus favoring its widening when they appear and causing the development of a new riverbed (Qt13) while the 1960s floodplain (Qt12) is becoming an old terrace located between 5 and 11 m above the new alluvial bottom. There are no previous records about this kind of consequences in the regional fluvial dynamics. El curso bajo del río Gállego ha sido fuertemente degradado desde los años 1960 por la actividad antrópica (extracción de áridos, acumulaciones de escombros, obras de encauzamiento) que ha conducido a una fuerte incisión. Aunque este tipo de procesos inducidos por el hombre son habituales en la bibliografía fluvial, en este caso se aprecian efectos más complejos. Son, por ejemplo, la profundidad y velocidad de la incisión, la falta de relación entre puntos de máxima intervención y los de mayor incisión o la continuidad del proceso cuarenta años después de cesar ese tipo de acciones. La respuesta a estos desajustes está en el papel que está jugando la exhumación del sustrato pleistoceno infrayacente, afectado por procesos sinsedimentarios de karstificación. La aparición de paleodolinas rellenas de sedimentos finos en el fondo y laterales de la incisión es actualmente el principal determinante de su importancia y continuidad. Además, estas paleodepresiones dirigen la dinámica y trazado del río y puntualmente favorecen ensanchamientos laterales. Esto propicia la aparición de un nuevo lecho (Qt13) a medida que el lecho de los años 1960 (Qt12) va quedando como una terraza colgada entre 5 y 11 m sobre el nuevo fondo aluvial. No hay antecedentes de este tipo de consecuencias en la dinámica fluvial regional

Linfoma angiocéntrico centrofacial

El linfoma angiocéntrico centrofacial es una neoplasia linfoide rara, con un diagnóstico a menudo difícil, debido al cuadro clínico inespecífico y a que muchas veces son necesarias varias biopsias para llegar a un diagnóstico correcto. Se trata de un linfoma no Hodgkin(LNH) agresivo, de localización preferente en el tracto respiratorio superior (sobre todo en cavidad nasal), y con un pronóstico ominoso, ya que la supervivencia media es de 12-18 meses aproximadamente(1). Predomina en orientales y sudamericanos, entre los 50-60 años de edad, y con ligera preferencia por el sexo masculino (2:1). Se presenta el caso de una paciente ecuatoriana que acude a nuestro servicio con edema hemifacial, rinorrea achocolatada y obstrucción respiratoria nasal de 1 mes de evolución, sin respuesta al tratamiento antibiótico y antiinflamatorio, que tras realizar varias pruebas diagnósticas se evidenció histológicamente la presencia de un linfoma T extranodal de tipo nasal (también llamado linfoma de células T angiocéntrico).The centrofacial angiocentric lymphoma is a rare lymphoid neoplasm, with an often-difficult diagnosis due to the non-specific clinical picture. On many occasions it is necessary to perform various biopsies to reach the correct diagnosis. This lymphoma is an aggressive Non-Hodgkin's (NHL) type, which is normally found in the upper respiratory tract (predominantly in the nasal cavity), and has an ominous prognosis, as the average survival rate is between 12 and 18 months (1). It is predominantly found in subjects of oriental and South American extraction, who are between the ages of 50 and 60 years and with a slight tendency towards males (2:1). This is the case study of a female Ecuadorian patient who was referred to our department with a hemifacial edema, chocolate- like rhinorrhea and nasal respiratory obstruction, which had been treated with antibiotics and anti-inflammatories for a month without success. After performing a number of diagnostic tests, it was found histologically that the patient had an extranodal T-cell lymphoma of the nasal type (also known as T-cell angiocentric lymphoma)

Changes in compliance with school-based physical activity recommendations in Spanish youth: The UP&DOWN longitudinal study

The study aimed (a) to examine changes in physical activity (PA) during the whole day, school hours, recess, and physical education classes (PEC) during a 2-year period in primary and secondary students; (b) to identify changes in the proportion of compliance with specific PA recommendations for these periods; and (c) to examine whether PA levels at baseline are associated with PA levels 2 years later. Eight hundred and fourteen (51.8% boys) children and 658 (50.1% boys) adolescents from 41 Spanish schools participated in the study. Hip-worn accelerometers were used to assess PA during different time periods. Light PA (LPA) declined during the whole day, school hours, recess (all P < 0.001, except child girls for recess), and PEC (all, P < 0.05) in children and adolescents. Moderate-to-vigorous PA (MVPA) during the whole day and recess declined in child boys (P < 0.01 and P < 0.001, respectively) and adolescent boys (P < 0.001 and P < 0.05, respectively). MVPA during PEC declined in adolescent boys (P < 0.001) and adolescent girls (all P < 0.05). The proportion of compliance with the specific PA recommendations for these periods declined (P < 0.05), except for PEC in adolescent girls. PA during the whole day at baseline was moderately associated with PA during the whole day years later (ICCs = 0.210-0.544, with one exception), but this association was lower for the school-based PA. In conclusion, time spent in MVPA and LPA during the whole day and recess declined over time in child and adolescent boys and during PEC in adolescents. These findings highlight the need to promote PA interventions in these settings

Symmetry constraints on phonon dispersion in graphene

Taking into account the constraints imposed by the lattice symmetry, we calculate the phonon dispersion for graphene with interactions between the first, second, and third nearest neighbors in the framework of the Born--von Karman model. Analytical expressions obtained for the dispersion of the out-of-plane (bending) modes give the nonzero sound velocity. The dispersion of four in-plane modes is determined by coupled equations. Values of the force constants are found in fitting with frequencies at critical points and with elastic constants measured on graphite.Comment: 5 pages, 2 figure

Defect characterization of UMG mc-Si solar cells using LBIC and luminescence imaging techniques

Upgraded metallurgical-grade silicon (UMG Si) solar cells with different ranges of efficiencies were characterized through electroluminescence imaging (ELi) and light-beam induced current (LBIC) measurements. The results showed a good correlation between the EL intensity and the efficiency of the solar cells. ELi images gave a bright contrast at the defects, grain boundaries and intragrain defects, and dark contrast inside the grain bodies. Metallic impurities are much more present in some cells due to the directional solidification of the Si ingot. Local short-circuit current mapping with LBIC measurements revealed a bright zone in the neighborhoods of the defects due to the depletion of impurities. Internal quantum efficiencies (IQE) and effective diffusion lengths (Leff) were calculated using different excitation wavelengths. High resolution LBIC measurements revealed micrometric clusters of impurities around intragrain defectsSpanish MINECO project, ref. ENE2014-56069-C4-4-R and “Junta de Castilla y León (Spain)” project number VA081U1