Magneto-Conductance Anisotropy and Interference Effects in Variable Range Hopping

We investigate the magneto-conductance (MC) anisotropy in the variable range hopping regime, caused by quantum interference effects in three dimensions. When no spin-orbit scattering is included, there is an increase in the localization length (as in two dimensions), producing a large positive MC. By contrast, with spin-orbit scattering present, there is no change in the localization length, and only a small increase in the overall tunneling amplitude. The numerical data for small magnetic fields $B$, and hopping lengths $t$, can be collapsed by using scaling variables $B_\perp t^{3/2}$, and $B_\parallel t$ in the perpendicular and parallel field orientations respectively. This is in agreement with the flux through a `cigar'--shaped region with a diffusive transverse dimension proportional to $\sqrt{t}$. If a single hop dominates the conductivity of the sample, this leads to a characteristic orientational `finger print' for the MC anisotropy. However, we estimate that many hops contribute to conductivity of typical samples, and thus averaging over critical hop orientations renders the bulk sample isotropic, as seen experimentally. Anisotropy appears for thin films, when the length of the hop is comparable to the thickness. The hops are then restricted to align with the sample plane, leading to different MC behaviors parallel and perpendicular to it, even after averaging over many hops. We predict the variations of such anisotropy with both the hop size and the magnetic field strength. An orientational bias produced by strong electric fields will also lead to MC anisotropy.Comment: 24 pages, RevTex, 9 postscript figures uuencoded Submitted to PR

Fabrication of strong magnetic micron-sized supraparticles with anisotropic magnetic properties for magnetorheology

Dr Tavacoli is acknowledged for useful discussions. This work was supported by MICINN PID2019-104883GB-I00 project (Spain), Junta de Andalucı´a P18-FR-2465 project and European Regional Development Fund (ERDF). J. R. M. acknowledges FPU14/01576 fellowship. E. C.-G. acknowledges financial support by CONACYT (Ref. #232347).We propose three different techniques to synthesize anisotropic magnetic supraparticles for their incorporation in the formulation of magnetorheological fluids with novel potential applications. The techniques include microtransfer molding, electrodeposition and microfluidic flow-focusing devices. Although the yield of these methods is not large, with their use, it is possible to synthesize supraparticles with anisotropy in both their magnetic content and shape. The magnetorheological characteristics (yield stress) of the resulting field-induced structures were computed using finite element method simulations and demonstrated to be strongly dependent on the microstructural anisotropy of the supraparticles. In anisotropic particles, the simulated yield stress is always larger than that of the isotropic ones consisting of magnetically homogeneous spherical particles.MICINN PID2019-104883GB-I00 project (Spain)Junta de Andalucía P18-FR-2465 projectEuropean Regional Development Fund (ERDF)FPU14/01576CONACYT (Ref. #232347

Global mRNA expression analysis in myosin II deficient strains of Saccharomyces cerevisiae reveals an impairment of cell integrity functions

<p>Abstract</p> <p>Background</p> <p>The <it>Saccharomyces cerevisiae MYO1 </it>gene encodes the myosin II heavy chain (Myo1p), a protein required for normal cytokinesis in budding yeast. Myo1p deficiency in yeast (<it>myo1Δ</it>) causes a cell separation defect characterized by the formation of attached cells, yet it also causes abnormal budding patterns, formation of enlarged and elongated cells, increased osmotic sensitivity, delocalized chitin deposition, increased chitin synthesis, and hypersensitivity to the chitin synthase III inhibitor Nikkomycin Z. To determine how differential expression of genes is related to these diverse cell wall phenotypes, we analyzed the global mRNA expression profile of <it>myo1Δ </it>strains.</p> <p>Results</p> <p>Global mRNA expression profiles of <it>myo1Δ </it>strains and their corresponding wild type controls were obtained by hybridization to yeast oligonucleotide microarrays. Results for selected genes were confirmed by real time RT-PCR. A total of 547 differentially expressed genes (p ≤ 0.01) were identified with 263 up regulated and 284 down regulated genes in the <it>myo1Δ </it>strains. Gene set enrichment analysis revealed the significant over-representation of genes in the protein biosynthesis and stress response categories. The <it>SLT2/MPK1 </it>gene was up regulated in the microarray, and a <it>myo1Δslt2Δ </it>double mutant was non-viable. Overexpression of ribosomal protein genes <it>RPL30 </it>and <it>RPS31 </it>suppressed the hypersensitivity to Nikkomycin Z and increased the levels of phosphorylated Slt2p in <it>myo1Δ </it>strains. Increased levels of phosphorylated Slt2p were also observed in wild type strains under these conditions.</p> <p>Conclusion</p> <p>Following this analysis of global mRNA expression in yeast <it>myo1Δ </it>strains, we conclude that 547 genes were differentially regulated in <it>myo1Δ </it>strains and that the stress response and protein biosynthesis gene categories were coordinately regulated in this mutant. The <it>SLT2/MPK1 </it>gene was confirmed to be essential for <it>myo1Δ </it>strain viability, supporting that the up regulated stress response genes are regulated by the <it>PKC1 </it>cell integrity pathway. Suppression of Nikkomycin Z hypersensitivity together with Slt2p phosphorylation was caused by the overexpression of ribosomal protein genes <it>RPL30 </it>and <it>RPS31</it>. These ribosomal protein mRNAs were down regulated in the <it>myo1Δ </it>arrays, suggesting that down regulation of ribosomal biogenesis may affect cell integrity in <it>myo1Δ </it>strains.</p

Calidad de vida y estrés en estudiantes de medicina en Cajamarca-Perú-2023

Objectives: Determine the influence of quality of life on the stress of medical students at a university in Cajamarca during 2023. Identify the level of quality of life and the degree of stress, and establish the dimensions of quality of life and others. factors that influence stress. Materials and methods: The present study was basic with a quantitative approach, cross-sectional with a correlational method. The student population was 175 students, and the sample was 106 students. The SISCO SV-21 questionnaire with Cronbach's alpha of 0.85 and the WHOQOL-BREF 26 questionnaire with Cronbach's alpha of 0.89 were used. For the treatment of the collected information, descriptive and inferential statistics were used with a level of significance p&lt;0.05 using the Excel statistical package and the Epi Info system. Results: We found 71.70% high levels of stress and 96 % of a low quality of life. A value of p = 0.317 was found with respect to the relationship of the two variables. Regarding the dimensions of the quality of life that predisposes to have high stress, it was found significant to psychological health (p = 0.0025) and PR of 2.88; and social relationships (p= 0.036). Finally, in relation to gender and presentation of stress (significant p of =0.0084) with PR of 1.37. Conclusion: There is no significant correlation between stress and the quality of life of medical students. There are high levels of stress and a feeling of poor quality of life among students. The female sex, mental health and social relationships are significantly related to high levels of stress.Objetivos: Determinar la influencia de la calidad de vida en el estrés de los estudiantes de medicina de una universidad de Cajamarca durante el 2023. Identificar el nivel de calidad de vida y el grado de estrés, y establecer las dimensiones de calidad de vida y otros factores que influyen en el estrés. Materiales y métodos:&nbsp;El presente estudio fue tipo básico con enfoque cuantitativo, de tipo transversal con método correlacional. La población de estudiantes fue de 175 estudiantes, y la muestra fue de 106 estudiantes. Se usó el cuestionario SISCO SV-21 con alfa de Cronbach del 0.85 y el cuestionario WHOQOL-BREF 26 con alfa de Cronbach del 0.89. Para el tratamiento de la información recolectada, se usó la estadística descriptiva e inferencial con un nivel de significancia p&lt;0.05 usando para ello el paquete estadístico Excel y el sistema Epi Info. Resultados: Encontramos un 71,70% altos niveles de estrés y 96% de una calidad de vida baja. Se halló un valor de p = 0.317 con respecto a la relación de las dos variables. Con respecto a las dimensiones de la calidad de vida que predispone a tener estrés alto, se encontró significativo a la salud psicológica (p = 0.0025) y RP de 2.88; y las relaciones sociales (p= 0.036). Finalmente, en relación a sexo y presentación de estrés (p significativo de =0,0084) con RP de 1.37. Conclusión: No existe correlación significativa entre el estrés y la calidad de vida de los estudiantes de medicina, Existen elevados niveles de estrés y de sensación de mala calidad de vida entre los estudiantes. El sexo femenino, la salud mental y las relaciones sociales se relacionan significativamente con elevados de estrés

Fox : a un año de la alternancia

Reflexiones críticas desde diversas disciplinas de las ciencias sociales acerca del primer año de gobierno de Vicente Fox Quesada. Entre los rubros que se analizan están: la política cultural, el sector rural, los jóvenes, los derechos humanos, la cultura indígena y la seguridad pública.ITESO, A.C

Detection of dengue virus serotype 2 in aedes aegypti in Quintana Roo, Mexico, 2011

Abstract. In October 2011, the State Health Department announced that several laboratory-confirmed cases of dengue had occurred among residents in two neighborhoods of Benito Juarez, Quintana Roo State, Mexico. To identify the dengue virus serotype(s) temporally and spatially associated with the cases, entomologic-based virus surveillance was initiated in October 2011 in both neighborhoods. Adult mosquitoes were collected from 88 houses by CDCbackpack aspirator, and all female Aedes aegypti L. (n = 419) were individually homogenized and assayed in pools of as many as 10 by reverse transcriptionpolymerase chain reaction (RT-PCR) using dengue virus-specific primers. Five (12%) of 41 pools were positive for dengue virus RNA. The individual mosquitoes that comprised the pools were analyzed separately by RT-PCR using dengue virus serotype-specific primers. Six mosquitoes were positive for dengue virus serotype-2 (DENV-2) RNA, three of which were collected in the same house. The mean number of female Ae. aegypti collected in each house was 4.76 ± 6.19. The overall dengue virus-infection rate in female Ae. aegypti was 1.4%. Interestingly, most (60%) of mosquito females were collected only from 15 (17%) houses. In summary, we provide evidence of recent DENV-2 transmission in Quintana Roo State

H4 Histamine Receptors Mediate Cell Cycle Arrest in Growth Factor-Induced Murine and Human Hematopoietic Progenitor Cells

The most recently characterized H4 histamine receptor (H4R) is expressed preferentially in the bone marrow, raising the question of its role during hematopoiesis. Here we show that both murine and human progenitor cell populations express this receptor subtype on transcriptional and protein levels and respond to its agonists by reduced growth factor-induced cell cycle progression that leads to decreased myeloid, erythroid and lymphoid colony formation. H4R activation prevents the induction of cell cycle genes through a cAMP/PKA-dependent pathway that is not associated with apoptosis. It is mediated specifically through H4R signaling since gene silencing or treatment with selective antagonists restores normal cell cycle progression. The arrest of growth factor-induced G1/S transition protects murine and human progenitor cells from the toxicity of the cell cycle-dependent anticancer drug Ara-C in vitro and reduces aplasia in a murine model of chemotherapy. This first evidence for functional H4R expression in hematopoietic progenitors opens new therapeutic perspectives for alleviating hematotoxic side effects of antineoplastic drugs

Building and surroundings: thermal coupling

Energy building performance can be different according to outdoor conditions or urban environment, at the same time that this last assess, buildings are also affected by the building envelope, as obvious consequence of the thermal and Aeraulic coupling existing between the indoor and outdoor conditions in buildings. Thus, in this coupling is fundamental to typify the transmission phenomenon through the building envelope. Doing this, it is possible to estimate transmission heating losses and gains and also the superficial temperatures of the envelope. In order to assess the transient behaviour of the building envelope it is necessary to develop a predictive model, precise enough, to be integrated in a simulating tool. Detailed and multidimensional models, based in numerical methods, like Finite Element Method (FEM), has a high precision, but its complexity imply resources consumption and computational time, too high to be integrated in these kind of tools. On the contrary, simplified methods are good enough because they are simple and fast, with an acceptable precision in almost all the situations. The present work is focused: (a) Firstly, to develop a simplified RC-network model. The aim of the model is to characterize and to implement with precision the behaviour of a wall in a simulating software tool based on urban environment, (b) secondly, to express in form of equivalences, the different indoor and outdoor excitations that can exist in the building envelope, and (c) finally, to calibrate the simplified model through its characteristic parameters. For a homogeneous wall and two types of excitations, it has been obtained the characteristic parameters of the model that represent the better adjustment to the real wall. In a first step, it has been obtained the results of the proposal model and a reference model based on FEM, in terms of wall external surface heat flow. Results of both models have been compared, and the resultant characteristic parameters of the model have been obtained through an optimisation method. Results for the wall and for the excitations under analysis show: (1) Characteristic longitude ec, or capacitive node position, it is determined according to a certain value of Fo equal to 2 for both excitations, this value remains constant in time, (2) useful wall thickness, on the contrary, vary as time function, according to a logarithmic law for both excitations, although this function is different depending on the considered excitation, (3) using a constant excitation, coefficients from the previous logarithmic function depends on the range of the excitation, while these are practically independent of the lineal excitation gradient