2,201 research outputs found
The flavor puzzle in multi-Higgs models
We reconsider the flavor problem in the models with two Higgs doublets. By
studying two generation toy models, we look for flavor basis independent
constraints on Yukawa couplings that will give us the mass hierarchy while
keeping all Yukawa couplings of the same order. We then generalize our findings
to the full three generation Standard Model. We find that we need two
constraints on the Yukawa couplings to generate the observed mass hierarchy,
and a slight tuning of Yukawa couplings of order 10%, much less than the
Standard Model. We briefly study how these constraints can be realized, and
show how flavor changing currents are under control for mixing in
the near-decoupling limit.Comment: 26 pages, typos are corrected, references are added, the final
versio
Modelling the influence of age of steel fibre reinforced self-compacting concrete on its compressive behaviour
Steel fibre reinforced self-compacting
concrete (SFRSCC) can combine the benefits of
self-consolidating concrete technology with those
derived from adding steel fibres to quasi-brittle
cement based materials. In a recent applied research
project joining pre-casting industry, private and
public research institutions, a method was developed
to design cost-competitive SFRSCC of rheological
and mechanical properties required for the prefabrication
of SFRSCC fac¸ade panels. To assure safe
demoulding process of the panels, the influence of the
concrete age on the compression behaviour of the
SFRSCC should be known. For this purpose, series of
tests with specimens of 12 h to 28 days were tested in
order to analyze the age influence on the compressive
strength, strain at peak stress, Young’s modulus, and
compressive volumetric fracture energy. The experimental
program was divided in two groups of test
series, one with SFRSCC of a volumetric fibre
percentage of 0.38% and the other with 0.57%. To
apply the obtained data in the design and numerical
analysis framework, the influence of the age on
these SFRSCC properties was modelled. This work
describes the carried out experimental program, presents and analyzes the obtained results, and
provides the derived analytical expressions
Heat in optical tweezers
Laser-induced thermal effects in optically trapped microspheres and single cells have been investigated by Luminescence Thermometry. Thermal spectroscopy has revealed a non-localized temperature distribution around the trap that extends over tens of microns, in agreement with previous theoretical models. Solvent absorption has been identified as the key parameter to determine laser-induced heating, which can be reduced by establishing a continuous fluid flow of the sample. Our experimental results of thermal loading at a variety of wavelengths reveal that an optimum trapping wavelength exists for biological applications close to 820 nm. This has been corroborated by a simultaneous analysis of the spectral dependence of cellular heating and damage in human lymphocytes during optical trapping. Minimum intracellular heating, well below the cytotoxic level (43 °C), has been demonstrated to occur for optical trapping with 820 nm laser radiation, thus avoiding cell damage
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Propriétés psychométriques de l’échelle de satisfaction des cours académiques (ESCA) chez les étudiants universitaires brésiliens
Academic satisfaction has been studied from different perspectives that considerate distinct ways of measurement. However, the plurality of evaluated facets prevents a more parsimonious assessment of the general students’ academic satisfaction. In the article, we aimed to provide psychometric evidence of the validity and reliability for the AMSS in Brazil in two studies (N = 893). In Study 1, an exploratory factor analysis and item parameters (Item Response Theory) support the one-factor solution and the suitability of the six items. Moreover, evidence for factorial invariance across gender and convergent validity with the PANAS and with the SWLS was also presented in Study 2. In conclusion, the present paper provides evidence of the adequacy of the AMSS to evaluate global satisfaction with the academics course in Brazil.Propiedades psicométricas de la Escala de Satisfacción del Curso Académico (ESCA) en estudiantes universitarios brasileños
La satisfacción académica ha sido estudiada bajo diferentes perspectivas, produciendo dife- rentes formas de medición. Sin embargo, la pluralidad de facetas evaluadas impide una evaluación más parsimoniosa de la satisfacción académica de los estudiantes en general. En este artÃculo, objetivamos proporcionar evidencias psicométricas de la validez y con- fiabilidad para el ESCA en Brasil en dos estudios (N = 893). En el Estudio 1, un análisis factorial exploratorio y los parámetros de los Ãtems (TeorÃa de Respuesta al Item) soportan la solución unifatorial y la adecuación de los seis Ãtems. Además, se presentaron evidencias de invariancia factorial entre género y validez convergente con el PANAS y con el ESV en el Estudio 2. En conclusión, este estudio proporciona evidencias de la adecuación de la ESCA para evaluar la satisfacción global con el curso académico en Brasil.A satisfação acadêmica tem sido estudada sob diferentes perspectivas que contemplam formas distintas de mensuração. Entretanto, a pluralidade de facetas avaliadas impede uma avaliação mais parcimoniosa da satisfação acadêmica dos estudantes em geral. O presente estudo tem por objetivo fornecer evidências psicométricas da validade e confiabilidade para o ESCA no Brasil em dois estudos (N = 893). No Estudo 1, uma análise fatorial exploratória e os parâmetros dos itens (Teoria de Resposta ao Item) suportam a solução unifatorial e a adequação dos seis itens. Além disso, foram apresentadas evidências de invariância fatorial entre gênero e validade convergente com o PANAS e com o ESV no Estudo 2. Em con- clusão, este estudo fornece evidências da adequação da ESCA para avaliar a satisfação global com o curso acadêmico na versão em português.La satisfaction académique a été étudiée sous différentes perspectives qui envisagent différentes formes de mesure. Cependant, la pluralité des facettes évaluées empêche une évaluation plus parcimonieuse de la satisfaction académique des étudiants en général. La pré- sente étude vise à fournir des preuves psychométriques de validité et de fiabilité pour ESCA au Brésil dans deux études (N = 893). Dans l’étude 1, une analyse factorielle exploratoire et les paramètres d’item (Théorie de la réponse à l’item) corroborent la solution à un facteur et l’adéquation des six items. En outre, nous avons présenté des preuves d’invariance factorielle entre le sexe et la validité convergentes avec PANAS et ESV dans l’étude 2. En conclusion, cette étude fournit des preuves de l’aptitude de l’ESCA à évaluer la satisfaction générale à l’égard du cours universitaire dans la version portugaise
New insights into the classification and nomenclature of cortical GABAergic interneurons.
A systematic classification and accepted nomenclature of neuron types is much needed but is currently lacking. This article describes a possible taxonomical solution for classifying GABAergic interneurons of the cerebral cortex based on a novel, web-based interactive system that allows experts to classify neurons with pre-determined criteria. Using Bayesian analysis and clustering algorithms on the resulting data, we investigated the suitability of several anatomical terms and neuron names for cortical GABAergic interneurons. Moreover, we show that supervised classification models could automatically categorize interneurons in agreement with experts' assignments. These results demonstrate a practical and objective approach to the naming, characterization and classification of neurons based on community consensus
Altered thymic differentiation and modulation of arthritis by invariant NKT cells expressing mutant ZAP70
Various subsets of invariant natural killer T (iNKT) cells with different cytokine productions develop in the mouse thymus, but the factors driving their differentiation remain unclear. Here we show that hypomorphic alleles of Zap70 or chemical inhibition of Zap70 catalysis leads to an increase of IFN-gamma-producing iNKT cells (NKT1 cells), suggesting that NKT1 cells may require a lower TCR signal threshold. Zap70 mutant mice develop IL-17-dependent arthritis. In a mouse experimental arthritis model, NKT17 cells are increased as the disease progresses, while NKT1 numbers negatively correlates with disease severity, with this protective effect of NKT1 linked to their IFN-gamma expression. NKT1 cells are also present in the synovial fluid of arthritis patients. Our data therefore suggest that TCR signal strength during thymic differentiation may influence not only IFN-gamma production, but also the protective function of iNKT cells in arthritis
Accounting Problems Under the Excess Profits Tax
DNA vaccines based on subunits from pathogens have several advantages over other vaccine strategies. DNA vaccines can easily be modified, they show good safety profiles, are stable and inexpensive to produce, and the immune response can be focused to the antigen of interest. However, the immunogenicity of DNA vaccines which is generally quite low needs to be improved. Electroporation and co-delivery of genetically encoded immune adjuvants are two strategies aiming at increasing the efficacy of DNA vaccines. Here, we have examined whether targeting to antigen-presenting cells (APC) could increase the immune response to surface envelope glycoprotein (Env) gp120 from Human Immunodeficiency Virus type 1 (HIV- 1). To target APC, we utilized a homodimeric vaccine format denoted vaccibody, which enables covalent fusion of gp120 to molecules that can target APC. Two molecules were tested for their efficiency as targeting units: the antibody-derived single chain Fragment variable (scFv) specific for the major histocompatilibility complex (MHC) class II I-E molecules, and the CC chemokine ligand 3 (CCL3). The vaccines were delivered as DNA into muscle of mice with or without electroporation. Targeting of gp120 to MHC class II molecules induced antibodies that neutralized HIV-1 and that persisted for more than a year after one single immunization with electroporation. Targeting by CCL3 significantly increased the number of HIV-1 gp120-reactive CD8(+) T cells compared to non-targeted vaccines and gp120 delivered alone in the absence of electroporation. The data suggest that chemokines are promising molecular adjuvants because small amounts can attract immune cells and promote immune responses without advanced equipment such as electroporation.Funding Agencies|Research Council of Norway; Odd Fellow</p
Pt-Sn/C as a possible methanol-tolerant cathode catalyst for DMFC
An effective method was developed for preparing highly dispersed nano-sized Pt–Sn/C electrocatalyst synthesised by a modified polyol reduction method. From XRD patterns, the Pt–Sn/C peaks shifted slightly to lower 2θ angles when compared with commercial Pt/C catalyst, suggesting that Sn formed alloy with Pt. Based on HR-TEM images, the Pt–Sn/C nanoparticles showed small particle sizes and well dispersed onto the carbon support with a narrow particle distribution. The methanol oxidation reaction on the as-prepared Pt–Sn/C catalyst appeared at lower currents (+7.08 mA at +480 mV vs. Ag/AgCl) compared to the commercial Pt/C (+8.25 mA at +480 mV vs. Ag/AgCl) suggesting that the Pt–Sn/C catalyst has ‘methanol tolerance capabilities’. Pt–Sn/C HA Slurry pH3 catalysts showed better activity towards the oxygen-reduction reaction (ORR) than commercial Pt/C which could be attributed to smaller particle sizes. In our study, the Pt–Sn/C catalyst appears to be a promising methanol-tolerant catalyst with activity towards the ORR in the DMFC.Web of Scienc
Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015
SummaryBackground The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding Bill & Melinda Gates Foundation
Geometric maximal operators and BMO on product bases
We consider the problem of the boundedness of maximal operators on BMO on
shapes in . We prove that for bases of shapes with an engulfing
property, the corresponding maximal function is bounded from BMO to BLO,
generalising a known result of Bennett for the basis of cubes. When the basis
of shapes does not possess an engulfing property but exhibits a product
structure with respect to lower-dimensional shapes coming from bases that do
possess an engulfing property, we show that the corresponding maximal function
is bounded from BMO to a space we define and call rectangular BLO
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