Spontaneous Symmetry Breakdown in non-relativistic Quantum Mechanics

The advantages and disadvantages of some pedagogical non-relativistic quantum-mechanical models, used to illustrate spontaneous symmetry breakdown, are discussed. A simple quantum-mechanical toy model (a spinor on the line, subject to a magnetostatic interaction) is presented, that exhibits the spontaneous breakdown of an internal symmetry.Comment: 19 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1111.1213. Equations (30) and (31) have been corrected. Other minor correction

Experiencia con rituximab en miopatía inflamatoria idiopática refractaria

Clinical and laboratory characteristics of two patients who received rituximab for refractory idiopathic inflammatory myopathy (IIM) are described. Patients were refractory to conventional treatment with disease-modifying antirheumatic drugs (DMARDs) so they received rituximab 1 g dose every 14 days in two biannual cycle infusions. Data of proximal muscle strength, pathognomonic skin lesions, CPK, SGOT, LDH and ESR, results of electromyography, muscle and skin biopsy were obtained from the medical records. None of the cases presented drug reaction or infections during and following infusions. Rituximab showed effectiveness in clinical and enzymatic response in patients with dermatomyositis refractory to corticosteroids and traditional DMARDs.Se describe las características clínicas y de laboratorio de dos pacientes que recibieron rituximab por miopatía inflamatoria idiopática(MII). Ellas eran refractarias a tratamiento convencional con DARMES, por lo que recibieron rituximab 1 gramo cada 14 días, en dosinfusiones en ciclo semestral. En las historias clínicas se obtuvo los datos clínicos de fuerza muscular proximal, lesiones cutáneaspatognomónicas, elevación de CPK, TGO, DHL y VSG, resultados de electromiografía, biopsia muscular y de piel. Ninguno de losdos casos presentó reacción medicamentosa ni infecciones durante y posterior a las infusiones. Rituximab mostró efectividad en larespuesta clínica y enzimática en estas pacientes con dermatomiositis refractarias a corticoides y DARMES tradicionales

A simulational and theoretical study of the spherical electrical double layer for a size-asymmetric electrolyte: the case of big coions

Monte Carlo simulations of a spherical macroion, surrounded by a size-asymmetric electrolyte in the primitive model, were performed. We considered 1:1 and 2:2 salts with a size ratio of 2 (i.e., with coions twice the size of counterions), for several surface charge densities of the macrosphere. The radial distribution functions, electrostatic potential at the Helmholtz surfaces, and integrated charge are reported. We compare these simulational data with original results obtained from the Ornstein-Zernike integral equation, supplemented by the hypernetted chain/hypernetted chain (HNC/HNC) and hypernetted chain/mean spherical approximation (HNC/MSA) closures, and with the corresponding calculations using the modified Gouy-Chapman and unequal-radius modified Gouy-Chapman theories. The HNC/HNC and HNC/MSA integral equations formalisms show good concordance with Monte Carlo "experiments", whereas the notable limitations of point-ion approaches are evidenced. Most importantly, the simulations confirm our previous theoretical predictions of the non-dominance of the counterions in the size-asymmetric spherical electrical double layer [J. Chem. Phys. 123, 034703 (2005)], the appearance of anomalous curvatures at the outer Helmholtz plane and the enhancement of charge reversal and screening at high colloidal surface charge densities due to the ionic size asymmetry.Comment: 11 pages, 7 figure

Multilayered Solar Energy Converters with Flexible Sequence of p and n Semiconductor Films

Non-traditional design of multi-layered solar energy converters is proposed, with electrically independent p-i-n junctions. This new approach allows utilization of cheap and abundant II-VI, IV and IV-VI materials instead of III-V ones, using also cheap and economic deposition techniques like Chemical Bath Deposition (CBD) or Chemical Vapor Deposition (CVD) instead of expensive Molecular Beam Epitaxy (MBE). The CVD reactor with three atomic sources was built and used. II-VI and IV-VI semiconductor materials were prepared either in CVD reactor, or by CBD techniques. Besides, the original two-stage technology was employed: first the precursor oxide/hydroxide film of corresponding metal (like cadmium oxide/hydroxide) was prepared by some variety of CBD methods, and at the second stage, in CVD reactor the non-metallic component of precursor film was substituted by chalcogen, producing materials like CdS, CdSe, PbTe, etc. The semiconductor materials thus produced were of high quality, with basic parameters corresponding to those for the single crystals. Several experimental multilayered converters were constructed (in particular, with CdS/CdTe, CdS/PbS and Si/PbTe active bilayers). The preliminary results of their studying have shown that these and similar devices can be used in solar cells and photo sensors with satisfactory efficiency, and have great potential for improvement

Electron transport measurements in liquid xenon with Xenoscope, a large-scale DARWIN demonstrator

The DARWIN observatory is a proposed next-generation experiment with 40 tonnes of liquid xenon as an active target in a time projection chamber. To study challenges related to the construction and operation of a multi-tonne scale detector, we have designed and constructed a vertical, full-scale demonstrator for the DARWIN experiment at the University of Zurich. Here, we present the first results from a several-months run with 343kg of xenon and electron drift lifetime and transport measurements with a 53cm tall purity monitor immersed in the cryogenic liquid. After 88days of continuous purification, the electron lifetime reached a value of (664±23)μs. We measured the drift velocity of electrons for electric fields in the range (25–75) V/cm, and found values consistent with previous measurements. We also calculated the longitudinal diffusion constant of the electron cloud in the same field range, and compared with previous data, as well as with predictions from an empirical model

Asymmetric cell division requires specific mechanisms for adjusting global transcription

Most cells divide symmetrically into two approximately identical cells. There are many examples, however, of asymmetric cell division that can generate sibling cell size differences. Whereas physical asymmetric division mechanisms and cell fate consequences have been investigated, the specific problem caused by asymmetric division at the transcription level has not yet been addressed. In symmetrically dividing cells the nascent transcription rate increases in parallel to cell volume to compensate it by keeping the actual mRNA synthesis rate constant. This cannot apply to the yeast Saccharomyces cerevisiae, where this mechanism would provoke a never-ending increasing mRNA synthesis rate in smaller daughter cells. We show here that, contrarily to other eukaryotes with symmetric division, budding yeast keeps the nascent transcription rates of its RNA polymerases constant and increases mRNA stability. This control on RNA pol II-dependent transcription rate is obtained by controlling the cellular concentration of this enzyme

Musicoterapia en una Unidad de Cuidados Intensivos Neonatales: experiencia benéfica para el binomio

ResumenIntroducciónDesde hace varios años se está utilizando la música como herramienta terapéutica y preventiva en la neonatología, se han documentado en un gran número de artículos de investigación, sin embargo, en México esta técnica es poco utilizada.ObjetivoMejorar las condiciones de los neonatos atendidos en una Unidad de Cuidados Intensivos (UCIN) y sus familiares, mediante el uso de musicoterapia, para minimizar el estrés y los daños colaterales.Materiales y métodosUn grupo de 2 neonatólogos, 3 residentes de pediatría, 10 enfermeras y un concertista profesional de violín, llevaron a cabo 6 sesiones musicales semanales en la Unidad de Cuidados Intensivos Neonatales Externos del Hospital Civil de Guadalajara. Durante el concierto se valoró individualmente a cada neonato, registrando los signos vitales por monitorización electrónica, además se registró el estado anímico de los familiares.ResultadosDurante las sesiones de música los neonatales no presentaron cambios significativos en sus constantes vitales, en el personal de la UCIN y en los padres de recién nacidos hospitalizados se vieron efectos benéficos, refiriendo disminución del estrés y altos índices de satisfacción.ConclusionesLa música puede tener un efecto positivo como terapia coadyuvante en neonatos de alto riesgo, principalmente en prematuros. Se recomienda difundir y aplicar esta metodología en las UCIN del país.AbstractIntroductionSince several years ago, music has been used as a therapeutic and preventive tool in neonatology. A great number of research papers have been written on the subject; however, this technique is rarely used in Mexico.ObjectiveTo improve the condition of neonates at Neonatal Intensive Care Units (NICU) and their relatives, in order to minimize any stress and collateral damage.Material and methods: A group of two neonatologists, 3 residents, 10 nurses and a professional concert violinist, conducted six weekly music sessions in the Outpatient Neonatal Intensive Care Unit (ONICU) of our institution. During the concert, we individually assessed each newborn, recording vital signs through electronic monitoring; additionally, we recorded the mood of any other family members present.ResultsDuring the music sessions, the neonatal patients showed no significant changes in vital signs; yet, ONICU staff and the parents/relatives of hospitalized newborns showed beneficial effects, reporting decreased stress and high levels of satisfaction.ConclusionsMusic can have a positive effect as adjunctive therapy in high-risk newborns, especially in premature babies. We therefore recommend applying this methodology in the ONICU

Efecto de las fuentes de polen sobre el rendimiento en la extracción de aceite y perfil de ácidos grasos de las semillas de dátil (Phoenix dactylifera L.) cultivar Medjool de México

The present investigation aimed to assess the effect of pollen sources on the mass, dimension, oil content and fatty acid profile of the seeds from female palms of the Medjool date cultivar. The palms were pollinated with Deglet Noor, Khadrawy, Medjool and Zahidi cultivars. In addition, three palms were pollinated as the treatment control. The fatty acids were evaluated by gas chromatography-mass spectrometry. The surface morphology of date seed powder was examined using SEM, before and after n-hexane interaction. The seeds of the Medjool treatment had the greatest mass (1.42 g), but the lowest oil content (5.37% w/w); the control seeds showed smaller mass (1.21 g), but higher oil content (13.57% w/w). The proportion of fatty acids varied significantly among the treatments with respect to the control. The most abundant fatty acids were oleic (C18:1), lauric (C12:0), myristic (C14:0), palmitic (C16:0), linoleic (C18:2), and stearic (C18:0). Together these fatty acids presented a composition between 98.3 and 98.67% for treatments, and 99.0% for the control. The results indicate that the pollen sources from Deglet Noor, Khadrawy, Medjool and Zahidi cultivars had a significant effect on mass, dimension, oil content and fatty acid profile of the seeds of the date cultivar Medjool. The date seed oil could be used as edible oil, in food products, and in pharmaceutical and cosmetic applications.La presente investigación tuvo como objetivo evaluar el efecto de las fuentes de polen, sobre la masa, dimensión, contenido de aceite y el perfil de ácidos grasos de las semillas de dátil del cultivar Medjool. Las palmas hembras del cultivar Medjool fueron polinizadas con cultivares Deglet Noor, Khadrawy, Medjool y Zahidi. Además, tres palmas fueron polinizadas como tratamiento control. Los ácidos grasos se evaluaron por cromatografía de gases-espectrometría de masas. La morfología de la superficie del polvo de semillas de dátil se examinó utilizando un equipo SEM, antes y después de la interacción n-hexano. Las semillas del tratamiento Medjool resultaron con mayor masa (1,42 g), pero menor contenido de aceite (5,37% p/p); la semilla control, mostró una masa más pequeña (1,21 g), pero un mayor contenido de aceite (13,57% p/p). La composición de ácidos grasos varió significativamente entre los tratamientos con respecto al control. Los ácidos grasos mayoritarios fueron: oleico (C18:1), láurico (C12:0), mirístico (C14:0), palmítico (C16:0), linoleico (C18:2) and esteárico (C18:0). En total, estos ácidos grasos alcanzan una composición entre 98.3 y 98.67% para los tratamientos, y 99.0% para el control. Los resultados indican que la fuente de polen de los cultivares Deglet Noor, Khadrawy, Medjool y Zahidi tiene un efecto significativo sobre la masa, dimensión, contenido de aceite y el perfil de ácidos grasos de la semilla del cultivar de dátil Medjool. El aceite de la semilla de dátil, podría usarse como aceite comestible, productos alimenticios, aplicaciones farmacéuticas y cosméticas

Musculoskeletal evaluation in severe haemophilia A patients from Latin America

There is a paucity of literature on haemophilia treatment in Latin American countries, a region characterized by rapidly improving systems of care, but with substantial disparities in treatment between countries. The aim of this study was to evaluate the musculoskeletal status of haemophilia patients from Latin America and to examine the relationship between musculoskeletal status and treatment practices across countries. The Committee of Latin America on the Therapeutics of Inhibitor Groups conducted a survey of its member country representatives on key aspects of haemophilia treatment in 10 countries. Musculoskeletal status of patients was obtained during routine comprehensive evaluations between March 2009 and March 2011. Eligible patients had severe haemophilia A (factor VIII <1%) without inhibitors (<0.6 BU mL−1) and were ≥5 years of age. Musculoskeletal status was compared between three groups of countries, based primarily on differences in the availability of long‐term prophylaxis. Overall, 143 patients (5–66 years of age) were enrolled from nine countries. In countries where long‐term prophylaxis had been available for at least 10 years (Group A), patients aged 5–10 years had significantly better mean World Federation of Hemophilia clinical scores, fewer target joints and fewer affected joints than patients from countries where long‐term prophylaxis has been available for about 5 years (Group B) or was not available (Group C). In Latin America, the musculoskeletal status of patients with severe haemophilia without inhibitors has improved significantly in association with the provision of long‐term prophylaxis. As more countries in Latin America institute this practice, further improvements are anticipated

Bold or shy? Examining the risk-taking behavior and neophobia of invasive and non-invasive house sparrows

Bold or shy? Examining the risk-taking behavior and neophobia of invasive and non-invasive house sparrows. Behavior provides a useful framework for understanding specialization, with animal personality aiding our understanding of the invasiveness of birds. Invasions imply dispersion into unknown areas and could require changes in behavior or spatial clustering based on personality. Reduced neophobia and increased exploring behavior could allow individuals to colonize new areas as they test and use non-familiar resources. Here, we hypothesized that house sparrow (Passer domesticus) individuals from invasive populations would exhibit bolder behavior than in non-invasive populations. We assessed risk taking and neophobia in male house sparrows in Barcelona (where it is considered native) and in Mexico City (where it has become widely invasive), captured in two different habitats, urban and non-urban. We assessed latency to enter an experimental cage and to explore it, and latency to feed and feeding time in the presence of a novel object. We found that sparrows from Mexico City, both from urban and non-urban areas, were quicker to enter the experimental cage than the sparrows from Barcelona. The time it took the birds to start exploring the cage gave a similar result. We found no differences between cities or habitats in the latency to feed and feeding time while exposed to a novel object. Our results partially support the view that the invader populations from Mexico City are bolder than those from Barcelona. Behavior is an important component of plasticity and its variability may have an important effect on adaptation to local situations. Future studies should disentangle the underlying mechanisms that explain the different personalities found in populations of different regions, contrasting populations of different densities, and taking different food availability scenarios into account.Peer reviewe