1,335 research outputs found
Characterization of an Aluminum-Lithium Alloy Based Composite Propellant at Elevated Pressures
Aluminum-lithium (Al-Li) alloys have demonstrated a mechanism to improve composite propellant performance by reducing agglomerates through microexplosions. In addition, use of Al-Li significantly reduces hydrochloric acid production in ammonium perchlorate based propellants while also improving theoretical performance. Full combustion characterization (e.g., at various pressures) of the Al-Li based propellant has not been performed previously. Measurement of the aluminum-lithium composite propellant’s burning rate and quantification of agglomerate production at various pressures is presented. Agglomerate size of the aluminum-lithium appeared to be smaller at lower pressures than at higher pressures, likely due to increased microexplosions at low pressures. Additionally, at high pressures the aluminum-lithium did appear to produce larger agglomerates than the aluminum, but upon closer inspection it was observed that the majority of these large agglomerates were liquid metal that had splashed off of the melt layer rather than condensed phase oxide products. This biased the aluminum-lithium samples towards larger agglomerate sizes without clear evidence the larger agglomerates would not burn given greater residence time and distance from the surface. Results show a pressure exponent of 0.29 for a composite propellant using aluminum-lithium powder sieved to 25-40 μm and 0.39 for a propellant using aluminum-lithium powder as-received. The difference in pressure exponents for the two powder sizes could be attributed to the greater microexplosivity increasing the burning rate at low pressure
¿Importa el tamaño de la adversidad?
Con este trabajo se busca idear un modelo que pueda determinar bajo qué
condiciones, a un candidato le convendrÃa ganar las elecciones presidenciales 2015 en Argentina y bajo qué condiciones no.
El modelo será desarrollado en el contexto de la teorÃa de juegos, ya que es considerado
como un instrumental ideal para analizar costos y beneficios en situaciones de decisiones
interpersonales, es decir, para identificar la mejor acción de una persona o ente, teniendo en cuenta las mejores decisiones de las otras personas o entes involucrados.Fil: Diez, Gonzalo Gabriel. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas
Programmable current converter synthesis for the evaluation of UV radiation of excimer lamps
This work proposes the development of a power supply for Dielectric Barrier Discharge (DBD) lamps, intended for the evaluation of a water treatment system based on UV radiation. The DBD excimer lamp is an attractive source of UV because of its cost and radiation power. The proposed converter is conceived to control the UV radiation by programming different lamp current intensities, duty cycles and frequencies. For the converter synthesis, a capacitive electric equivalent model of the DBD is used. A simulation of the converter and its control analysis is presented
Computational chemical analysis of unconjugated bilirubin anions and insights into pKa values clarification
The pKa, the negative logarithm of the acid dissociation equilibrium constant, of the carboxylic acid groups of unconjugated bilirubin in water is a discussed issue because there are quite different experimental values reported. Using quantum mechanical calculations we have studied the conformational behavior of unconjugated bilirubin species (in gas phase and in solution modeled implicitly and explicitly) to provide evidence that may clarify pKa values because of its pathophysiological relevance. Our results show that rotation of carboxylate group, which is not restricted, settles it in a suitable place to establish stronger interactions that stabilizes the monoanion and the dianion to be properly solvated, demonstrating that the rationalization used to justify the high pKa values of unconjugated bilirubin is inappropriate. Furthermore, low unconjugated bilirubin (UCB) pKa values were estimated from a linear regression analysis.Centro de QuÃmica Inorgánic
Characterization of mammalian Lipocalin UTRs in silico: Predictions for their role in posttranscriptional regulation
The Lipocalin family is a group of homologous proteins characterized by its big array of functional capabilities. As extracellular proteins, they can bind small hydrophobic ligands through a well-conserved β-barrel folding. Lipocalins evolutionary history sprawls across many different taxa and shows great divergence even within chordates. This variability is also found in their heterogeneous tissue expression pattern. Although a handful of promoter regions have been previously described, studies on UTR regulatory roles in Lipocalin gene expression are scarce. Here we report a comprehensive bioinformatic analysis showing that complex post-transcriptional regulation exists in Lipocalin genes, as suggested by the presence of alternative UTRs with substantial sequence conservation in mammals, alongside a high diversity of transcription start sites and alternative promoters. Strong selective pressure could have operated upon Lipocalins UTRs, leading to an enrichment in particular sequence motifs that limit the choice of secondary structures. Mapping these regulatory features to the expression pattern of early and late diverging Lipocalins suggests that UTRs represent an additional phylogenetic signal, which may help to uncover how functional pleiotropy originated within the Lipocalin family.Ministerio de Ciencia e Innovación BFU2015-68149-RMinisterio de EconomÃa, Industria y Competitividad, Gobierno de España BFU2011-2397
Control of the neuroprotective Lipocalin Apolipoprotein D expression by alternative promoter regions and differentially expressed mRNA 5’ UTR variants
The Lipocalin Apolipoprotein D (ApoD) is one of the few genes consistently overexpressed in the aging brain, and in most neurodegenerative and psychiatric diseases. Its functions include metabolism regulation, myelin management, neuroprotection, and longevity regulation. Knowledge of endogenous regulatory mechanisms controlling brain disease-triggered ApoD expression is relevant if we want to boost pharmacologically its neuroprotecting potential. In addition to classical transcriptional control, Lipocalins have a remarkable variability in mRNA 5’UTR-dependent translation efficiency. Using bioinformatic analyses, we uncover strong selective pressures preserving ApoD 5’UTR properties, indicating unexpected functional conservation. PCR amplifications demonstrate the production of five 5’UTR variants (A-E) in mouse ApoD, with diverse expression levels across tissues and developmental stages. Importantly, Variant E is specifically expressed in the oxidative stress-challenged brain. Predictive analyses of 5’UTR secondary structures and enrichment in elements restraining translation, point to Variant E as a tight regulator of ApoD expression. We find two genomic regions conserved in human and mouse ApoD: a canonical (α) promoter region and a previously unknown region upstream of Variant E that could function as an alternative mouse promoter (β). Luciferase assays demonstrate that both α and β promoter regions can drive expression in cultured mouse astrocytes, and that Promoter β activity responds proportionally to incremental doses of the oxidative stress generator Paraquat. We postulate that Promoter β works in association with Variant E 5’UTR as a regulatory tandem that organizes ApoD gene expression in the nervous system in response to oxidative stress, the most common factor in aging and neurodegeneration
An Evolutionary Perspective of the Lipocalin Protein Family
The protein family of Lipocalins is ubiquitously present throughout the tree of life, with the exception of the phylum Archaea. Phylogenetic relationships of chordate Lipocalins have been proposed in the past based on protein sequence similarities, but their highly divergent primary structures and a shortage of experimental annotations in genome projects have precluded a well-supported hypothesis for their evolution. In this work we propose a novel topology for the phylogenetic tree of chordate Lipocalins, inferred from multiple amino acid sequence alignments. Sixteen jawed vertebrates with fair coverage by genomic sequencing were compared. The selected species span an evolutionary range of ∼400 million years, allowing for a balanced representation of all major vertebrate clades. A consensus phylogenetic tree is proposed following a comparison of sequence-based maximum-likelihood trees and protein structure dendrograms. This new phylogeny suggests an APOD-like common ancestor in early chordates, which gave rise, via whole-genome or tandem duplications, to the six Lipocalins currently present in fish (APOD, RBP4, PTGDS, AMBP, C8G, and APOM). Further gene duplications of APOM and PTGDS resulted in the altogether 15 Lipocalins found in contemporary mammals. Insights into the functional impact of relevant amino acid residues in early diverging Lipocalins are also discussed. These results should foster the experimental exploration of novel functions alongside the identification of new members of the Lipocalin family.España Ministerio de Ciencia e Innovación grant PID2019-110911RB-I0
High-sensitivity troponin is associated with high risk clinical profile and outcome in acute heart failure
Background: The aim of the study was to evaluate the value of high-sensitivity cardiac troponin (hs-cTn) for identifying high-risk patients.
Methods and results: One hundred and eighty-seven patients admitted with acute heart failure (HF) (without myocardial infarction) were consecutively included; hs-cTn was measured at admission; the relation between elevated hs-cTn and the clinical outcome during hospitalization and at 90 days was analyzed; 93% (n = 174) had hs-cTn above the maximal normal value (14 ng/L); median hs-cTn was 42 ng/L (IQR 24–81). Patients with ejection fraction (EF) ≤ 45% had higher hs-cTn values (p = 0.0004). Patients with low cardiac output syndrome (LCOS) or shock had higher troponin levels compared with those with less severe clinical presentations (p = 0.004). Patients who required inotropic presented higher troponin values (p = 0.002), troponin values were also higher in those requiring complex therapies (intra-aortic balloon pump, mechanical ventilation or hemodialysis, p = 0.002). At 90-day follow-up, 28 (15.5%) patients died and 27 rehospitalizations occurred (55 events). The risk of events was greater in patients with hs-cTn > 42 ng/L (0.021), low blood pressure at admission (p = 0.002), LCOS or shock (p < 0.0001), EF ≤ 45% (p = 0.005) and inotropic use (p < 0.0001). In multivariate analysis, only inotropic agents requirements was associated independently with a high risk of death or rehospitalizations at 90 days (p = 0.007).
Conclusions: Elevation of hs-cTn is a finding almost constant in patients with decompensated HF. In subjects with higher troponin levels ventricular dysfunction is frequent. The use of hs-cTn for risk stratification at admission helps to identify populations with poor outcome during hospitalization and increased risk of death or rehospitalizations during follow-up who will require rapid implementation of aggressive treatment.
Emotional Intelligence in Physical Activity, Sports and Judo: A Global Approach.
Emotional intelligence (EI) has been studied in relation to health and physical activity
(PA) or in a sport-specific approach. EI is related to sports performance; however, combat sports
seem to show characteristics of their own that involve better control of emotions than other sports.
This study aimed to analyse whether there are differences in EI dimensions between those who do
not achieve World Health Organization (WHO) PA recommendations, those who meet WHO PA
recommendations, those who meet WHO PA recommendations practising sports, and judokas of
different levels. A descriptive and cross-sectional study was conducted. The sample comprised
2938 undergraduate students from Madrid and 487 active Spanish judokas. PA was measured
by the Global Physical Activity Questionnaire (GPAQ). EI was assessed by the Trait Meta-Mood
Scale (TMMS-24). Three different one-way ANOVA and ANCOVA (controlling for gender and age)
were conducted to compare the effect of type of group studied on the EI dimensions. Significant
differences in EI dimensions were found between those who do not meet PA recommendations, those
who meet PA recommendations, those who meet PA recommendations practising sports, and judo
athletes of different levels. However, when controlling for gender and age, these differences remained
specifically in emotional attention and in emotional repair. Judo athletes and high-performance judo
athletes showed better EI than the rest of the studied groups.post-print375 K
Amélioration des conditions d’hygiène et d’assainissement dans la commune de Zè au Bénin
La présente étude vise à évaluer les effets des interventions mises en œuvre de 2017 à 2018 relatives à la promotion de l'hygiène et de l'assainissement dans la commune de Zè. Réalisée en Septembre 2019, l’étude a mobilisé la recherche documentaire, l’observation et l’entretien. La collecte a été effectuée dans les arrondissements bénéficiaires des interventions et de celles non bénéficiaires. Les résultats après interventions montrent que la proportion des personnes ayant de bonnes pratiques d’hygiène et d’assainissement est passée de 31,01% à 73,08%. La proportion des groupements de femmes associés aux activités IEC/WASH est passée de 0% à 87%. Le taux de morbidité liée aux maladies hydro-fécales a régressé de 1,20% à 0,78%. La prévalence des géohelminthiases a diminué de 7,10% à 0,75%. Par ailleurs, l’observation a permis de constater la réduction de la défécation à l’air libre, la réduction de la distance séparant les ménages d’un point d’eau, la diminution de la corvée d’eau pour les femmes et les filles, la réduction de la prévalence des maladies courantes dans les localités bénéficiaires. Malgré les résultats positifs obtenus, il reste des défis à relever pour pérenniser les acquis et passer à l’échelle supérieure notamment l’implication effective des autorités locales dans le suivi des ouvrages d’hygiène et d’assainissement.
The study aims to assess the effects of the interventions implemented from 2017 to 2018 relating to the promotion of hygiene and sanitation in the municipality of Zè. Conducted in September 2019, the study involved documentary research, observation and interview. Collection was carried out in the districts benefiting from the interventions and those not benefiting. Postintervention results show that the proportion of people with good hygiene and sanitation practices increased from 31.01% to 73.08%. The proportion of women's groups involved in IEC / WASH activities increased from 0% to 87%. The morbidity rate linked to hydro-fecal diseases fell from 1.20% to 0.78%. The prevalence of soil-transmitted helminthiasis decreased from 7.10% to 0.75%. In addition, the observation made it possible to note the reduction in open defecation, the reduction in the distance separating households from a water point, the reduction in the drudgery of water for women and girls, reducing the prevalence of common diseases in beneficiary localities and empowering women in groups through the manufacture and sale of soap
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