Anisotropy of spin-orbit induced electron spin relaxation in [001] and [111] grown GaAs quantum dots

We report a systematic study of the spin relaxation anisotropy between single electron Zeeman sublevels in cuboidal GaAs quantum dots (QDs). The QDs are subject to an in-plane magnetic field. As the field orientation varies, the relaxation rate oscillates periodically, showing ``magic'' angles where the relaxation rate is suppressed by several orders of magnitude. This behavior is found in QDs with different shapes, heights, crystallographic orientations and external fields. The origin of these angles can be traced back to the symmetries of the spin admixing terms of the Hamiltonian. In [001] grown QDs, the suppression angles are different for Rashba and Dresselhaus spin-orbit terms. By contrast, in [111] grown QDs they are the same, which should facilitate a thorough suppression of spin-orbit induced relaxation. Our results evidence that cubic Dresselhaus terms play a critical role in determining the spin relaxation anisotropy even in quasi-2D QDs.Comment: 8 pages, 6 figs, submitted to PRB on 07/30/1

Contrastación de diferentes criterios numéricos para la resolución de flujos potenciales mediante el empleo de coordenadas curvilíneas. Parte I: Función de corriente

En este trabajo se analizan y contrastan diferentes criterios numéricos para la resolución de flujos potenciales subsónicos compresibles mediante el empleo de la función de corriente. Los dominios son discretizados en base a la generación de coordenadas curvilíneas adaptables a los contornos. Las ecuaciones de discretización son obtenidas a partir de la ecuación diferencial de la función de corriente, o bien de efectuar balances sobre volúmenes de control finitos asignados a los nodos de la malla. A modo de ejemplo y para el estudio numérico se analizan dos situaciones concretas de flujos confinados; los resultados presentados ponen de manifiesto la influencia del tipo de malla generada y de los criterios numéricos utilizados en la discretización de las ecuaciones.Peer Reviewe

Seed germination and seedling allogamy in Rosmarinus officinalis: the costs of inbreeding

1) Self-pollination by geitonogamy is likely in self-compatible plants that simultaneously expose large numbers of flowers to pollinators. However, the progeny of these plants is often highly allogamous. Although mechanisms to increase cross-pollination have been identified and studied, their relative importance has rarely been addressed simultaneously in plant populations. (2) We used Rosmarinus officinalis to explore the factors that influence the probability of self-fertilization due to geitonogamy or that purge its consequences, focusing on their effect on seed germination and allogamy rate. For doing this, we experimentally tested the effects of geitonogamy on the proportion of filled seeds and how it influences germination rates. Then during two field seasons, we studied how life-history and flowering traits of individuals influence seed germination and allogamy rates of their progeny in wild populations at the extremes of the altitudinal range. The traits considered were plant size, population density, duration of the flowering season, number of open flowers, flowering synchrony among individuals within populations, and the proportion of male-sterile flowers. (3) We found that most seeds obtained experimentally from self-pollinations were apparently healthy but in fact empty, and that the presence of filled seeds drove the differences in germination rates between self- and cross-pollination experiments. Plants from wild populations consistently showed low germination rates and high rates of allogamy as determined with microsatellites. Germination rates related positively to the length of the flowering season, flowering synchrony and the rate of male-sterile flowers whereas the rate of allogamous seedlings was positively related only to the rate of male-sterile flowers. (4) Rosemary plants purge most of the inbreeding caused by its pollination system by aborting seeds. This study showed that the rates of seed germination and of the resulting allogamy are a function of a complex combination of factors that vary in space and time. Male sterility of flowers, length of the flowering season and flowering synchrony of individuals within populations all favor high rates of cross-pollination, therefore increasing germination and allogamy rates. These flowering traits appear to be highly plastic and respond to local and seasonal environmental conditions

Autophagy plays an important role in protecting Pacific oysters from OsHV-1 and Vibrio aestuarianus infections.

Recent mass mortality outbreaks around the world in Pacific oysters, Crassostrea gigas, have seriously affected the aquaculture economy. Although the causes for these mortality outbreaks appear complex, infectious agents are involved. Two pathogens are associated with mass mortality outbreaks, the virus ostreid herpesvirus 1 (OsHV-1) and the bacterium Vibrio aestuarianus. Here we describe the interactions between these 2 pathogens and autophagy, a conserved intracellular pathway playing a key role in innate immunity. We show for the first time that autophagy pathway is present and functional in Pacific oysters and plays an important role to protect animals from infections. This study contributes to better understand the innate immune system of Pacific oysters.This work was partially funded through the EU project Bivalife (FP7 KBBE, contract n 266157), the Poitou Charentes Region and DPMA (Direction des p^eches maritimes et de l’aquaculture, AESTU project). David Rubinsztein is aWellcome Trust Prinicipal Research Fellow.This is the final published version. It first appeared at http://www.tandfonline.com/doi/full/10.1080/15548627.2015.1017188

Energy efficiency of ventilated façades with near infrared range reflective ceramic tiles

La creciente concienciación social respecto a la construcción sostenible y el ahorro energético en edificios está conduciendo a prescriptores y usuarios finales a tomar en consideración nuevas soluciones constructivas. Sin embargo, su introducción en el mercado es lenta y difícil, debido tanto a las limitaciones de las herramientas reconocidas de simulación térmica, que no permiten efectuar estimaciones integrando sistemas innovadores, como a la dificultad para validar su eficiencia en edificios reales previamente a su comercialización. En el presente trabajo se analiza la eficiencia energética de una fachada ventilada resuelta con baldosas cerámicas reflectantes al infrarrojo cercano, mediante la integración en el programa EnergyPlus de un modelo matemático que ha sido validado en el edificio experimental CIES Living Lab de Castellón.The growing social awareness with regard to sustainable construction and energy efficiency in buildings is leading specifications writers and end users to take into account new construction solutions. However, the introduction of these construction solutions into the market is slow and difficult owing to the limitations of the recognised thermal simulation tools, which do not allow estimations to be made when integrating innovative systems, and to the difficulty of validating their efficiency in actual buildings before marketing them. The present study analyses the energy efficiency of a ventilated façade made up of near-infrared reflective ceramic tiles, by integrating a mathematical model validated in the CIES Living Lab experimental building in Castellón into the EnergyPlus program.Este estudio ha sido cofinanciado por la plataforma Climate- KIC en el marco del proyecto Building Technologies Accelerator (BTA)

Serum methylarginines and spirometry-measured lung function in older adults

Rationale: Methylarginines are endogenous nitric oxide synthase inhibitors that have been implicated in animal models of lung disease but have not previously been examined for their association with spirometric measures of lung function in humans. Objectives: This study measured serum concentrations of asymmetric and symmetric dimethylarginine in a representative sample of older community-dwelling adults and determined their association with spirometric lung function measures. Methods: Data on clinical, lifestyle, and demographic characteristics, methylated arginines, and L-arginine (measured using LC-MS/MS) were collected from a population-based sample of older Australian adults from the Hunter Community Study. The five key lung function measures included as outcomes were Forced Expiratory Volume in 1 second, Forced Vital Capacity, Forced Expiratory Volume in 1 second to Forced Vital Capacity ratio, Percent Predicted Forced Expiratory Volume in 1 second, and Percent Predicted Forced Vital Capacity. Measurements and Main Results: In adjusted analyses there were statistically significant independent associations between a) higher asymmetric dimethylarginine, lower Forced Expiratory Volume in 1 second and lower Forced Vital Capacity; and b) lower L-arginine/asymmetric dimethylarginine ratio, lower Forced Expiratory Volume in 1 second, lower Percent Predicted Forced Expiratory Volume in 1 second and lower Percent Predicted Forced Vital Capacity. By contrast, no significant associations were observed between symmetric dimethylarginine and lung function. Conclusions: After adjusting for clinical, demographic, biochemical, and pharmacological confounders, higher serum asymmetric dimethylarginine was independently associated with a reduction in key measures of lung function. Further research is needed to determine if methylarginines predict the decline in lung function

Aging enhances contraction to thromboxane A2 in aorta from female senescence mice

The time-course for aging-associated effects on vascular reactivity to U46619, a stable analogue of thromboxane A2 (TXA2), was studied in aorta from female senescence-accelerated mice-prone (SAMP8), a murine model of accelerated senescence. SAMP8 and senescence-accelerated mice-resistant (SAMR1) were divided into three groups: 3-, 6- and 10-month-old. Contractile curves to U46619 (10−9 to 10−6 M) were performed in aortic rings in the absence or in the presence of nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 10−4 M) and/or cyclooxygenase (COX) inhibitor indomethacin (10−5 M). Protein and gene expression for COX-1 and COX-2 were determined by immunofluorescence and real-time PCR, respectively. Maximal contraction to U46619 was markedly higher in SAMP8 at all ages. In SAMR1, increases were seen at 10 months, while SAMP8 displays augmented contraction at 6 months, which was further increased at 10 months. L-NAME enhanced U46619 contractions in both 6-month-old groups, although the increase was higher on vessels from SAMR1 at this age. Indomethacin equally increased U46619 contractions in both 3-month-old groups, suggesting the production of vasodilator prostaglandin in young animals. In contrast, at 6 and 10 months indomethacin decreased U46619 contractions in both groups, indicating an aging-associated swap to a release of contractile prostanoids in aorta. In conclusion, aging enhances contractile responses to TXA2 in aorta from female mice by a mechanism involving a decrease of NO production and increased action of contractile prostanoids. This process occurs earlier in SAMP8 mice, establishing these mice as good model to study cardiovascular aging in a convenient and standard time-course

Brain structural signatures of negative symptoms in depression and schizophrenia.

Negative symptoms occur in several major mental health disorders with undetermined mechanisms and unsatisfactory treatments; identification of their neural correlates might unveil the underlying pathophysiological basis and pinpoint the therapeutic targets. In this study, participants with major depressive disorder (n = 24), schizophrenia (n = 22), and healthy controls (n = 20) were assessed with 10 frequently used negative symptom scales followed by principal component analysis (PCA) of the scores. A linear model with the prominent components identified by PCA was then regressed on gray and white-matter volumes estimated from T1-weighted magnetic resonance imaging. In depressed patients, negative symptoms such as blunted affect, alogia, withdrawal, and cognitive impairment, assessed mostly via clinician-rated scales were inversely associated with gray matter volume in the bilateral cerebellum. In patients with schizophrenia, anhedonia, and avolition evaluated via self-rated scales inversely related to white-matter volume in the left anterior limb of internal capsule/anterior thalamic radiation and positively in the left superior longitudinal fasiculus. The pathophysiological mechanisms underlying negative symptoms might differ between depression and schizophrenia. These results also point to future negative symptom scale development primarily focused on detecting and monitoring the corresponding changes to brain structure or function.This work was supported by Brain and Behavior Research Foundation (NARSAD) and Medical Research Council (MRC) awards to GKM, and by the Wellcome Trust/MRC Behavioural and Clinical Neuroscience Institute, University of Cambridge. We thank Dr. Zheng Ye for her help with image analysis and technical support, Niels Reinders and staff at the Wolfson Brain Imaging Centre for help with data collection, and staff at IAPT, CAMEO and the Rehabilitation and Recovery Service in the Cambridgeshire and Peterborough NHS Foundation Trust for help with recruitment. The study was supported by infrastructure provided by the Wellcome Trust/MRC Behavioural and Clinical Neuroscience Institute at the University of Cambridge.This is the final version published by Frontiers here: http://journal.frontiersin.org/Journal/10.3389/fpsyt.2014.00116/abstract

Reduction in ventral striatal activity when anticipating a reward in depression and schizophrenia: a replicated cross-diagnostic finding.

In the research domain framework (RDoC), dysfunctional reward expectation has been proposed to be a cross-diagnostic domain in psychiatry, which may contribute to symptoms common to various neuropsychiatric conditions, such as anhedonia or apathy/avolition. We used a modified version of the Monetary Incentive Delay (MID) paradigm to obtain functional MRI images from 22 patients with schizophrenia, 24 with depression and 21 controls. Anhedonia and other symptoms of depression, and overall positive and negative symptomatology were also measured. We hypothesized that the two clinical groups would have a reduced activity in the ventral striatum when anticipating reward (compared to anticipation of a neutral outcome) and that striatal activation would correlate with clinical measures of motivational problems and anhedonia. Results were consistent with the first hypothesis: two clusters in both the left and right ventral striatum were found to differ between the groups in reward anticipation. Post-hoc analysis showed that this was due to higher activation in the controls compared to the schizophrenia and the depression groups in the right ventral striatum, with activation differences between depression and controls also seen in the left ventral striatum. No differences were found between the two patient groups, and there were no areas of abnormal cortical activation in either group that survived correction for multiple comparisons. Reduced ventral striatal activity was related to greater anhedonia and overall depressive symptoms in the schizophrenia group, but not in the participants with depression. Findings are discussed in relation to previous literature but overall are supporting evidence of reward system dysfunction across the neuropsychiatric continuum, even if the specific clinical relevance is still not fully understood. We also discuss how the RDoC approach may help to solve some of the replication problems in psychiatric fMRI research.Supported by the Wellcome Trust Institutional Strategic Support Fund [097814/Z/11], a MRC Clinician Scientist [G0701911], a Brain and Behavior Research Foundation Young Investigator, and an Isaac Newton Trust award to Dr Murray; an award to Dr Segarra from the Secretary for Universities and Research of the Ministry of Economy and Knowledge of the Government of Catalonia and the European Union; by the University of Cambridge Behavioural and Clinical Neuroscience Institute, funded by a joint award from the Medical Research Council [G1000183]and Wellcome Trust [093875/Z/10/Z]; by awards from the Wellcome Trust [095692] and the Bernard Wolfe Health Neuroscience Fund to Dr. Fletcher, and by the Cambridge NIHR Biomedical Research Centre.This is the final version of the article. It first appeared from Frontiers via http://dx.doi.org/10.3389/fpsyg.2015.0128