A four-equation two-phase flow model for sodium boiling simulation of LMFBR fuel assemblies

A three-dimensional numerical model for the simulation of sodium boiling transients has been developed. The model uses mixture mass and energy equations, while employing a separate momentum equation for each phase. Thermal equilibrium on the saturation line between coexisting phases is assumed.The four governing equations are supplemented by a number of constitutive relations, addressing the interphase and intraphase exchanges, as well as the fluid-solid interactions. It should be noted that this four-equation two-phase flow model requires only one interfacial relation, i.e., the momentum exchange, compared to the six-equation model which needs two additional relations, describing the mass and energy exchanges. Consequently, the relatively high degree of uncertainty currently associated with the interfacial exchange phenomena is considerably reduced.From a numerical point of view, the basic approach in this work is a semi-implicit method, in which pressure pulse propagation and local effects characterized by short characteristic times are treated implicitly, while convective transport and diffusion heat transfer phenomena, associated with longer time constants, are handled explicitly. The method remains tractable and efficient in multidimensional applications.Simulation of a number of experiments has yielded very encouraging results. The numerical method and the constitutive relations have performed well, especially so in light of the extreme severity of the conditions involving sodium boiling

The dual nature of trehalose in citrus canker disease: A virulence factor for Xanthomonas citri subsp. citri and a trigger for plant defence responses

Xanthomonas citri subsp. citri (Xcc) is a bacterial pathogen that causes citrus canker in susceptible Citrus spp. The Xcc genome contains genes encoding enzymes from three separate pathways of trehalose biosynthesis. Expression of genes encoding trehalose-6-phosphate synthase (otsA) and trehalose phosphatase (otsB) was highly induced during canker development, suggesting that the two-step pathway of trehalose biosynthesis via trehalose-6-phosphate has a function in pathogenesis. This pathway was eliminated from the bacterium by deletion of the otsA gene. The resulting XccΔotsA mutant produced less trehalose than the wild-type strain, was less resistant to salt and oxidative stresses, and was less able to colonize plant tissues. Gene expression and proteomic analyses of infected leaves showed that infection with XccΔotsA triggered only weak defence responses in the plant compared with infection with Xcc, and had less impact on the host plant's metabolism than the wild-type strain. These results suggested that trehalose of bacterial origin, synthesized via the otsA-otsB pathway, in Xcc, plays a role in modifying the host plant's metabolism to its own advantage but is also perceived by the plant as a sign of pathogen attack. Thus, trehalose biosynthesis has both positive and negative consequences for Xcc. On the one hand, it enables this bacterial pathogen to survive in the inhospitable environment of the leaf surface before infection and exploit the host plant's resources after infection, but on the other hand, it is a tell-tale sign of the pathogen's presence that triggers the plant to defend itself against infection.Fil: Piazza, Ainelén Melanie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Zimaro, Tamara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Garavaglia, Betiana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Ficarra, Florencia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Thomas, Ludivine. King Abdullah University of Science and Technology; Arabia SauditaFil: Marondedze, Claudius. King Abdullah University of Science and Technology; Arabia SauditaFil: Feil, Regina. Max Planck Institute of Molecular Plant Physiology; AlemaniaFil: Lunn, John E.. Max Planck Institute of Molecular Plant Physiology; AlemaniaFil: Gehring, Chris. King Abdullah University of Science and Technology; Arabia SauditaFil: Ottado, Jorgelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gottig Schor, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

Sexual violence as a public health issue: the importance of searching for the aggressor

Apesar de predominar junto à população a idéia de que a violência sexual é praticada por pessoas desconhecidas, na realidade a maioria desses crimes é praticada por pessoa identificável pela vítima. Além de conseqüências físicas e psicológicas, também há risco em adquirir o vírus HIV. Para prevenção deste, em situação de risco, há orientação para uso da quimioprofilaxia anti-retroviral. Esse uso, por 28 dias, pode trazer efeitos adversos com intensidades variáveis. O conhecimento da sorologia anti-HIV do agressor torna-se fundamental para manter, ou suspender, com segurança, essa indicação. Este estudo descritivo, realizado no Conjunto Hospitalar de Sorocaba, teve como objetivo identificar os agressores e suas respectivas sorologias. Foi realizado a partir de fichas de notificação e os prontuários no período de julho de 2003 a dezembro de 2005. Encontraram-se 920 vítimas de violência sexual, com idades entre oito meses e 77 anos, havendo predomínio do sexo feminino (86,5 por cento). Dentre os agressores, 76 por cento foram referidos como identificáveis. Indicou-se profilaxia anti-retroviral para 24,9 por cento das vítimas. Para 80 (33,2 por cento) agressores localizados, a busca foi realizada através de contato telefônico. Encontrou-se 52,5 por cento em seus domicílios, 45 por cento em Presídio/Delegacia e 2,5 por cento no Pronto Socorro. Um agressor (1,3 por cento) apresentou sorologia positiva para HIV. As buscas encerraram-se, em sua maioria, em até seis dias (80 por cento), possibilitando a suspensão da quimioprofilaxia em 30,6 por cento dos casos. Concluiu-se que a busca ao denunciado permitiu conhecer sua sorologia anti-HIV e suspender, para um terço das vítimas, o uso da quimioprofilaxia anti-retroviral, diminuindo, com isso, a possibilidade de efeitos adversosAlthough people believe that sexual violence is practiced by unknown people, most crimes are actually practiced by someone close to the victim. Besides physical and psychological consequences, there is the risk of acquiring the HIV virus. To prevent the latter, in risky situations, the advice is to use antiretroviral chemoprophylaxis during 28 days. This therapy may bring adverse effects. Knowing the aggressor's anti-HIV serology is vital to safely maintain or suspend the therapy indication. This descriptive study, carried out at Conjunto Hospitalar de Sorocaba, aimed to identify the aggressors and their serology. The study was conducted after analyzing notification index cards and charts from July 2003 to December 2005, in 30 months of active search. The researchers found 920 sexual violence victims, with ages ranging from 8 months to 77 years, most of them female (86.5%). Concerning the aggressors, 76% were referred to as identifiable. Antiretroviral prophylaxis was advised to 24.9% of the victims. For 80 (33.2%) aggressors who were found, the search was carried out through telephone calls. Regarding the places where the aggressors were located, 52.5% were found at home, 45% in a prison/police station and 2.5% in the Emergency Room. One aggressor (1.3%) presented positive HIV serology. Most searches were concluded within 6 days (80%), allowing the suspension of chemoprophylaxis in 30.6% of the cases. It was concluded that after finding the aggressors and learning about their anti-HIV serology, the use of antiretroviral chemoprophylaxis could be safely suspended in one third of the victims, therefore reducing the chances of adverse effect

Advanced information processing system for advanced launch system: Avionics architecture synthesis

The Advanced Information Processing System (AIPS) is a fault-tolerant distributed computer system architecture that was developed to meet the real time computational needs of advanced aerospace vehicles. One such vehicle is the Advanced Launch System (ALS) being developed jointly by NASA and the Department of Defense to launch heavy payloads into low earth orbit at one tenth the cost (per pound of payload) of the current launch vehicles. An avionics architecture that utilizes the AIPS hardware and software building blocks was synthesized for ALS. The AIPS for ALS architecture synthesis process starting with the ALS mission requirements and ending with an analysis of the candidate ALS avionics architecture is described

Good practice in mental health care for socially marginalised groups in Europe: a qualitative study of expert views in 14 countries

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

The bacterial hydrophobin BslA is a switchable ellipsoidal Janus nanocolloid

BslA is an amphiphilic protein that forms a highly hydrophobic coat around <i>Bacillus subtilis</i> biofilms, shielding the bacterial community from external aqueous solution. It has a unique structure featuring a distinct partition between hydrophilic and hydrophobic surfaces. This surface property is reminiscent of synthesized Janus colloids. By investigating the behavior of BslA variants at water-cyclohexane interfaces through a set of multiscale simulations informed by experimental data, we show that BslA indeed represents a biological example of an ellipsoidal Janus nanoparticle, whose surface interactions are, moreover, readily switchable. BslA contains a local conformational toggle, which controls its global affinity for, and orientation at, water–oil interfaces. This adaptability, together with single-point mutations, enables the fine-tuning of its solvent and interfacial interactions, and suggests that BslA could be a basis for biotechnological applications

Laser-UV-microirradiation of interphase nuclei and posttreatment with caffeine: a new approach to establish the arrangement of interphase chromosomes

Laser UV microirradiation of Chinese hamster interphase cells combined with caffeine post-treatment produced different patterns of chromosome damage in mitosis following irradiation of a small area of the nucleus that may be classified in three categories: I) intact metaphase figures, II) chromosome damage confined to a small area of the metaphase spread, III) mitotic figures with damage on all chromosomes. Category III might be the consequence of a non-localized distortion of nuclear metabolism. By contrast, category II may reflect localized DNA damage induced by microirradiation, which could not be efficiently repaired due to the effect of caffeine. If this interpretation is right, in metaphase figures of category II chromosome damage should occur only at the irradiation site. The effect might then be used to investigate neighbourhood relationships of individual chromosomes in the interphase nucleus

High glucose concentration stimulates intracellular renin activity and angiotensin II generation in rat mesangial cells

Increased intrarenal renin-angiotensin system activity contributes to diabetic nephropathy. ANG II generation in mesangial cells (MC) is increased by high-glucose (HG) exposure. This study assessed the mechanisms involved in the glucose-induced ANG II generation in rat MC. Under basal conditions, MC mainly secreted prorenin. HG decreased prorenin secretion and induced a striking 30-fold increase in intracellular renin activity. After 72 h of HG exposure, only the mRNA levels for angiotensinogen and angiotensin-converting enzyme (ACE) were significantly elevated. However, after shorter periods of 24 h of HG stimulation the mRNA levels of the enzymes prorenin and cathepsin B, besides that for ACE, were significantly increased. the results suggest that the HG-induced increase in ANG II generation in MC results from an increase in intracellular renin activity mediated by at least three factors: a time-dependent stimulation of ( pro) renin gene transcription, a reduction in prorenin enzyme secretion, and an increased rate of conversion of prorenin to active renin, probably mediated by cathepsin B. the increase in angiotensinogen mRNA in parallel to increased renin activity indicates that HG also increased the availability of the renin substrate. the consistent upregulation of ACE mRNA suggests that, besides renin, ACE is directly involved in the increased mesangial ANG II generation induced by HG.UNIFESP, Div Renal, BR-04023900 São Paulo, BrazilUNIFESP, Div Renal, BR-04023900 São Paulo, BrazilWeb of Scienc

Biological activity differences between TGF-β1 and TGF-β3 correlate with differences in the rigidity and arrangement of their component monomers

[Image: see text] TGF-β1, -β2, and -β3 are small, secreted signaling proteins. They share 71–80% sequence identity and signal through the same receptors, yet the isoform-specific null mice have distinctive phenotypes and are inviable. The replacement of the coding sequence of TGF-β1 with TGF-β3 and TGF-β3 with TGF-β1 led to only partial rescue of the mutant phenotypes, suggesting that intrinsic differences between them contribute to the requirement of each in vivo. Here, we investigated whether the previously reported differences in the flexibility of the interfacial helix and arrangement of monomers was responsible for the differences in activity by generating two chimeric proteins in which residues 54–75 in the homodimer interface were swapped. Structural analysis of these using NMR and functional analysis using a dermal fibroblast migration assay showed that swapping the interfacial region swapped both the conformational preferences and activity. Conformational and activity differences were also observed between TGF-β3 and a variant with four helix-stabilizing residues from TGF-β1, suggesting that the observed changes were due to increased helical stability and the altered conformation, as proposed. Surface plasmon resonance analysis showed that TGF-β1, TGF-β3, and variants bound the type II signaling receptor, TβRII, nearly identically, but had small differences in the dissociation rate constant for recruitment of the type I signaling receptor, TβRI. However, the latter did not correlate with conformational preference or activity. Hence, the difference in activity arises from differences in their conformations, not their manner of receptor binding, suggesting that a matrix protein that differentially binds them might determine their distinct activities

Perturbation of Chromatin Structure Globally Affects Localization and Recruitment of Splicing Factors

Chromatin structure is an important factor in the functional coupling between transcription and mRNA processing, not only by regulating alternative splicing events, but also by contributing to exon recognition during constitutive splicing. We observed that depolarization of neuroblastoma cell membrane potential, which triggers general histone acetylation and regulates alternative splicing, causes a concentration of SR proteins in nuclear speckles. This prompted us to analyze the effect of chromatin structure on splicing factor distribution and dynamics. Here, we show that induction of histone hyper-acetylation results in the accumulation in speckles of multiple splicing factors in different cell types. In addition, a similar effect is observed after depletion of the heterochromatic protein HP1α, associated with repressive chromatin. We used advanced imaging approaches to analyze in detail both the structural organization of the speckle compartment and nuclear distribution of splicing factors, as well as studying direct interactions between splicing factors and their association with chromatin in vivo. The results support a model where perturbation of normal chromatin structure decreases the recruitment efficiency of splicing factors to nascent RNAs, thus causing their accumulation in speckles, which buffer the amount of free molecules in the nucleoplasm. To test this, we analyzed the recruitment of the general splicing factor U2AF65 to nascent RNAs by iCLIP technique, as a way to monitor early spliceosome assembly. We demonstrate that indeed histone hyper-acetylation decreases recruitment of U2AF65 to bulk 3' splice sites, coincident with the change in its localization. In addition, prior to the maximum accumulation in speckles, ∼20% of genes already show a tendency to decreased binding, while U2AF65 seems to increase its binding to the speckle-located ncRNA MALAT1. All together, the combined imaging and biochemical approaches support a model where chromatin structure is essential for efficient co-transcriptional recruitment of general and regulatory splicing factors to pre-mRNA