Voltage Sensing in Bacterial Protein Translocation

The bacterial channel SecYEG efficiently translocates both hydrophobic and hydrophilic proteins across the plasma membrane. Translocating polypeptide chains may dislodge the plug, a half helix that blocks the permeation of small molecules, from its position in the middle of the aqueous translocation channel. Instead of the plug, six isoleucines in the middle of the membrane supposedly seal the channel, by forming a gasket around the translocating polypeptide. However, this hypothesis does not explain how the tightness of the gasket may depend on membrane potential. Here, we demonstrate voltage-dependent closings of the purified and reconstituted channel in the presence of ligands, suggesting that voltage sensitivity may be conferred by motor protein SecA, ribosomes, signal peptides, and/or translocating peptides. Yet, the presence of a voltage sensor intrinsic to SecYEG was indicated by voltage driven closure of pores that were forced-open either by crosslinking the plug to SecE or by plug deletion. We tested the involvement of SecY’s half-helix 2b (TM2b) in voltage sensing, since clearly identifiable gating charges are missing. The mutation L80D accelerated voltage driven closings by reversing TM2b’s dipolar orientation. In contrast, the L80K mutation decelerated voltage induced closings by increasing TM2b’s dipole moment. The observations suggest that TM2b is part of a larger voltage sensor. By partly aligning the combined dipole of this sensor with the orientation of the membrane-spanning electric field, voltage may drive channel closure

Water ice deuteration: a tracer of the chemical history of protostars

Context. Millimetric observations have measured high degrees of molecular deuteration in several species seen around low-mass protostars. The Herschel Space Telescope, launched in 2009, is now providing new measures of the deuterium fractionation of water, the main constituent of interstellar ices. Aims. We aim at theoretically studying the formation and the deuteration of water, which is believed to be formed on interstellar grain surfaces in molecular clouds. Methods. We used our gas-grain astrochemical model GRAINOBLE, which considers the multilayer formation of interstellar ices. We varied several input parameters to study their impact on water deuteration. We included the treatment of ortho- and para-states of key species, including H2, which affects the deuterium fractionation of all molecules. The model also includes relevant laboratory and theoretical works on the water formation and deuteration on grain surfaces. In particular, we computed the transmission probabilities of surface reactions using the Eckart model, and we considered ice photodissociation following molecular dynamics simulations. Results. The use of a multilayer approach allowed us to study the influence of various parameters on the abundance and the deuteration of water. Deuteration of water is found to be very sensitive to the ortho-to-para ratio of H2 and to the total density, but it also depends on the gas/grain temperatures and the visual extinction of the cloud. Since the deuteration is very sensitive to the physical conditions, the comparison with sub-millimetric observation towards the low-mass protostar IRAS 16293 allows us to suggest that water ice is formed together with CO2 in molecular clouds with limited density, whilst formaldehyde and methanol are mainly formed in a later phase, where the condensation becomes denser and colder.Comment: Accepted for publication to A&A. 24 pages, 10 figure

CONSTRUCTION AND VALIDATION OF THE PARENTAL ASSESSMENT QUESTIONNAIRE FOR CHILDREN’S EMOTIONAL COMPETENCE (URPEKD)

The aim of the research was to construct and validate The Parental Assessment Questionnaire for Children\u27s Emotional Competence (URPEKD). The factorial structure, reliability, validity and sensitivity of the whole questionnaire, as well as the discriminability of individual items were checked, and the best items selected to be captured by the measurement construct were selected. Factor analysis resulted in a two-factor solution that explained 59.845 % of the total variance. The first factor that is saturated with eight items is called The perception, understanding and expression of one\u27s emotions. The second factor that is saturated with six items is called Perception, understanding, and expression of others\u27 emotions. The reliability of the entire scale, as well as its subscales is satisfactory. The construct validity of the URPEKD instrument was verified by its association with a similar instrument for students - UEK-45 (Takšić, 2002). There is a significant correlation between the stated factors of both questionnaires indicating satisfactory validity. The instrument is suitable for the use of measuring primary school children’s emotional competence by their parents

Origen social, competencias lingüísticas y patrones de publicación científica en Argentina, Brasil y Chile

Este artigo analisa as condições de aquisição de competência linguística em língua inglesa e o uso de idiomas estrangeiros nas publicações de pesquisadores da Argentina, Brasil e Chile. A análise se baseia nos  resultados de um questionário cross-national respondido por uma amostra do conjunto de pesquisadores  integrados ao núcleo central do sistema científico de cada país. O foco principal do artigo são as  modalidades de aquisição da competência  linguística e sua relação com características sociodemográficas, como a origem social, e com a  trajetória de formação. Além disso, o artigo analisa a relação entre as competências linguísticas e a  publicação científica, e explora a variação disciplinar no uso de idiomas estrangeiros. Os resultados mostram que existe uma associação entre  origem social, trajetória de formação, modalidades de aquisição da  competência em inglês e o nível  dessas competências. No entanto,  independentemente do domínio da língua, a maioria dos pesquisadores dos três países publica em inglês, e,  em todos os casos, seu nível de competência tem impacto sobre suas estratégias de escrita (autônomas, colaborativas ou via tradução profissional). Em termos comparativos, os pesquisadores brasileiros são os  que mais publicam em inglês, embora, no caso chileno, a menor proporção de publicações nessa língua possa se  dever ao maior peso dos pesquisadores em ciências sociais e humanas na amostra, uma vez que, nessas disciplinas, pelo menos na América Latina, o inglês não  adquiriu o mesmo status de língua franca que  nas ciências naturais.En este artículo se analizan las  condiciones de adquisición de  competencia lingüística en lenguainglesa y el uso de idiomas extranjeros en las publicaciones de investigadores de Argentina, Brasil y Chile. El análisis se basa en los resultados de una encuesta cross-national realizada a muestras de investigadores integrados al núcleo central del sistema científico de cada país. En relación con el foco principal del artículo, se abordan las modalidades de adquisición de la competencia lingüística y su relación con factores sociodemográficos, como el origen social, y con la trayectoriaformativa. Por otra parte, se analiza la relación entre las competencias  lingüísticas y la publicación científica, y se explora el lugar de las disciplinas en el uso de idiomas extranjeros. Los  resultados ponen en evidencia que existe una asociación entre el origen social, la trayectoria formativa, lasmodalidades de adquisición de  competencias en inglés y el nivel de dichas competencias. Sin embargo, e independientemente de su dominio de la lengua, la mayoría de los  investigadores de los tres países publica en inglés y, en todo caso, su nivel de competencia tiene incidencia en las estrategias de escritura (autónomas, colaborativas o por traducción profesional). En términoscomparativos, los científicos brasileños son los que más publican en inglés, aunque en el caso chileno la menor proporción de publicaciones en esta lengua podría deberse al mayor peso que tienen en su muestra los  investigadores de ciencias sociales y humanas, toda vez que, en estasdisciplinas, al menos en América Latina, el inglés no ha adquirido un estatus de lingua franca equivalente al de las ciencias naturales.This article analyzes the conditions of acquisition of linguistic competence in the English language and the use of foreign languages in the publications of researchers from Argentina, Brazil and Chile. The analysis is based on the results of a cross-national survey  carried out on samples of the researchers most integrated into the central nucleus of the scientific system of each country. In relation to the main focus of the article, the modalities of acquisition of linguistic competenceand its relationship with sociodemographic factors, such as social origin, and with the educationaltrajectory are addressed. On the other hand, the association between  linguistic competence and scientific publication, and the place of scientific disciplines in the use of foreign  languages are analyzed. The results show that there is a connection  between social origin, educational trajectory, ways of acquiring English skills and the level of these skills.  However, and regardless of theirlinguistic proficiency, the majority of researchers in the three countries  publish in English and, in any case, their level of competence has an impact on writing strategies (whether autonomous, collaborative or mediated by professional translation). In comparative terms, Brazilian  scientists publish the most in English, although in the Chilean case the lower proportion of publications in this language could be due to the greater weight of social and human scientists in the sample, since, in these disciplines, at least in Latin America, English has not acquired a lingua  franca status equivalent to that of the natural sciences

El estrés de los enfermeros que actúan en una unidad de terapia intensiva

The present study aimed to identify the presence of stress in nurses working in intensive care units, the stressing agents and symptoms associated to the nurses' perceptions of stress, and to assess the correlation between the occurrence of stress, sources of stress, and symptoms shown by the nurses. Seventy-five nurses took part in the study. the data were collected from questionnaires, analyzed with the Pearson correlation coefficients, and adjusted by general linear models. the study showed the presence of stress related to work dissatisfaction, activities regarded as critical situations in intensive care units, symptoms related to cardiovascular, digestive and musculoskeletal disorders. the conclusion is that stress is present in nurses' activities in intensive care units, related to characteristics of the health area itself, causing dissatisfaction and stress-related symptoms.O presente estudo teve como objetivos identificar a presença de estresse em enfermeiros que trabalham em unidades de terapia intensiva, identificar os agentes estressores e sintomas associados à percepção do enfermeiro ao estresse e avaliar a correlação entre a presença de estresse, fontes de estresse e sintomas apresentados pelos enfermeiros. Setenta e cinco enfermeiros participaram do estudo. Os dados foram obtidos por questionário. A analise foi realizada através do uso de coeficientes de correlação de Pearson e ajustados modelos lineares generalizados. O estudo mostrou a presença de estresse correlacionado à insatisfação com o trabalho, atividades consideradas como situações críticas em unidade de terapia intensiva, os sintomas relacionados às alterações cardiovasculares, aparelho digestivo e músculo-esquelético. A compreensão final é que o estresse está presente na atividade do enfermeiro em unidade de terapia intensiva, correlacionado com fatores pertinentes ao setor, gerando insatisfação com a profissão e sintomas ligados ao estresse.Hosp Israelita Albert Einstein, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc

Heat Conduction in Complex Metallic Alloys

Thermal conductivity, κ, of ε-phase Al73Pd25Fe2 and "Bergman phase" Mg-Al-Zn is presented, which resembles the features common to all complex metallic alloys: relatively low value, shallow local maximum or change of slope at approximately 50 K, and a rise above 100 K. The electron contribution, κel, is calculated using Wiedemann-Franz law, while the calculation of the phonon thermal conductivity, κph, below 50 K is calculated employing Debye model. The sum of the two does not explain the experimental data at higher temperatures (above 100 K). This discrepancy is analyzed in three competitive ways: assuming an increase of an effective Lorenz number, taking into account the hopping of localized lattice vibrations, and employing a "bipolar diffusion effect", known from the theory of semiconductors. While the results of the former two approaches confirm other findings in literature, "bipolar diffusion effect" needs to be adopted for the specific electron structure of complex metallic alloys.</p

Dynamics of Cyclic GMP Synthesis in Retinal Rods

AbstractIn retinal rods, Ca2+ exerts negative feedback control on cGMP synthesis by guanylate cyclase (GC). This feedback loop was disrupted in mouse rods lacking guanylate cyclase activating proteins GCAP1 and GCAP2 (GCAPs−/−). Comparison of the behavior of wild-type and GCAPs−/− rods allowed us to investigate the role of the feedback loop in normal rod function. We have found that regulation of GC is apparently the only Ca2+ feedback loop operating during the single photon response. Analysis of the rods' light responses and cellular dark noise suggests that GC normally responds to light-driven changes in [Ca2+] rapidly and highly cooperatively. Rapid feedback to GC speeds the rod's temporal responsiveness and improves its signal-to-noise ratio by minimizing fluctuations in cGMP

Slant, Fan, and Narrow: the Response of Stellar Streams to a Tilting Galactic Disk

Stellar streams are sensitive tracers of the gravitational potential, which is typically assumed to be static in the inner Galaxy. However, massive mergers like Gaia-Sausage-Enceladus can impart torques on the stellar disk of the Milky Way that result in the disk tilting at rates of up to 10-20 deg/Gyr. Here, we demonstrate the effects of disk tilting on the morphology and kinematics of stellar streams. Through a series of numerical experiments, we find that streams with nearby apocenters $(r_{\rm apo} \lesssim 20~\rm{kpc})$ are sensitive to disk tilting, with the primary effect being changes to the stream's on-sky track and width. Interestingly, disk tilting can produce both more diffuse streams and more narrow streams, depending on the orbital inclination of the progenitor and the direction in which the disk is tilting. Our model of Pal 5's tidal tails for a tilting rate of 15 deg/Gyr is in excellent agreement with the observed stream's track and width, and reproduces the extreme narrowing of the trailing tail. We also find that failure to account for a tilting disk can bias constraints on shape parameters of the Milky Way's local dark matter distribution at the level of 5-10%, with the direction of the bias changing for different streams. Disk tilting could therefore explain discrepancies in the Milky Way's dark matter halo shape inferred using different streams.Comment: 24 pages (+2 appendix), 15 figures, submitted to ApJ. Comments welcome. v2: fixed rendering issue with Fig. 11 on some device

Pueblos originarios y Estado municipal en Bahía Blanca (Argentina). Búsquedas interculturales y respuestas institucionales en una ciudad desigual

Bahía Blanca es una ciudad media del sudoeste de la Provincia de Buenos Aires (Argentina) en la cual la presencia indígena es frecuentemente negada. En el marco del trabajo de campo realizado, orientado a la obtención de un Doctorado en Antropología Social, en este artículo analizamos una serie de ordenanzas municipales y sus expedientes fechados entre los años 1990 y 2015. Nuestro objetivo general consiste en conocer y describir las demandas que distintas referentes indígenas elevaron al Estado municipal, así como las instituciones, fuerzas políticas, organizaciones y personas particulares que intervinieron en estos procesos. Asimismo, cruzamos la información de estas fuentes escritas con entrevistas etnográficas en las que nuestras interlocutoras se refieren a su militancia etnopolítica, lo cual nos permitió problematizar el contenido de la documentación oficial. Con todo, este trabajo constituye un aporte significativo para historizar las relaciones entre quienes reivindicaron y reivindican sus identidades étnicas en Bahía Blanca y el Estado municipal, a partir de documentos que, hasta el momento, no habían sido estudiados.Bahía Blanca is a city of around 300,000 inhabitants, located in the southwest of Buenos Aires province (Argentina), where the presence of originary peoples is often denied. Framed in our field work leading to a PhD in Social Anthropology, this article analyses a series of files related to ten municipal ordinances, dated between 1990 and 2015. Our main objective is to learn about and describe the demands that different indigenous local leaders presented to the Municipal State. Likewise, we seek to find out which institutions, political forces, organizations and individuals intervened in these processes. In addition, we compare the information from these written sources with ethnographic interviews, which allowed us to problematize the content of the official documents. Based on these documents that, until now, have not been studied, this work represents a meaningful contribution to historicize the relationship between those who vindicated and still vindicate their ethnic identities in Bahía Blanca and the Municipal State.Fil: Denis, Ana Clara. Universidad Nacional del Sur. Departamento de Humanidades; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentin