1,024 research outputs found
Direct Detection Signals from Absorption of Fermionic Dark Matter
We present a new class of direct detection signals; absorption of fermionic
dark matter. We enumerate the operators through dimension six which lead to
fermionic absorption, study their direct detection prospects, and summarize
additional constraints on their suppression scale. Such dark matter is
inherently unstable as there is no symmetry which prevents dark matter decays.
Nevertheless, we show that fermionic dark matter absorption can be observed in
direct detection and neutrino experiments while ensuring consistency with the
observed dark matter abundance and required lifetime. For dark matter masses
well below the GeV scale, dedicated searches for these signals at current and
future experiments can probe orders of magnitude of unexplored parameter space.Comment: 7 pages, 2 figures. v2: published in PRL with minor revisions and
changes to Fig 2 (no change to results
Retinoic acid induces the differentiation of B cell hybridomas from patients with common variable immunodeficiency.
Human-human B cell hybridomas constructed from B lymphocytes of common variable immunodeficiency (CVI) patients and the nonsecreting cell line WIL2/729 HF consistently secrete low levels of Ig and appear to retain a defect characteristic of the CVI patient's B cells. We assessed the differentiative capacity of retinoic acid (RA) on these hybridomas, as well as on hybridomas constructed from normal B cells and from patients with selective IgA deficiency. RA at concentrations varying between 10(-5) and 10(-9) M augmented IgM secretion 4-20-fold from four of four CVI hybridomas tested, but did not affect Ig secretion from normal or IgA-deficiency hybridomas. In support of this elevated Ig secretion, RA enhanced the de novo synthesis of biosynthetically labeled light (kappa) and heavy (mu) Ig (up to 4- and 15-fold, respectively) in the CVI hybridoma line JK32.1. The increase in IgM synthesis/secretion could not be accounted for by RA-induced alteration in the cell cycle. In inducing this increase in IgM production, RA was found to affect two aspects of Ig gene expression: (a) the steady-state levels of heavy and light chain mRNAs were enhanced, and (b) the processing of mu heavy chain transcripts to the secreted mRNA form became favored over the membrane mRNA form. We also show that expression of Leu-17 (CD38), a surface marker that is re-expressed in the late pre-plasma stage of B cell development, was increased by RA from less than 20% to greater than 90% of the total cell population, with a concomitant 4-10-fold augmentation in the mean fluorescence intensity. Changes in both Leu-17 expression and de novo Ig synthesis were prominent by 24 h, but could be observed as early as 8 h after induction. Taken together, our study demonstrates that RA affects a marked alteration in the differentiated state of the CVI hybridoma clones. This finding suggests that retinoids can enhance the functional capabilities of B cells with defects in maturation and support further studies to evaluate their clinical potential in CVI
Procesos de mejora y cambio en una escuela venezolana
El artículo presenta un estudio de caso de un proceso de mejora en una escuela venezolana. Con la finalidad de identificar y describir las políticas y medidas que se pusieron en práctica analizando los efectos y consecuencias de las mismas buscando identificar de igual manera la relación existente entre las políticas y medidas y los cambios percibidos por la comunidad docent
Ressources cognitives et développement territorial : une analyse textuelle appliquée aux politiques locales de développement durable
International audienceThis paper focuses on how the development of a particular region consistently requires actors to share a certain level of cognitive resources. In the case studied here - the Nord Pas-de-Calais region, this cognitive proximity is built via the local policies involving sustainable development. In order to comprehend the way local communities of the region activate this resource, we used textual data treatment analyzing about thirty interviews. The results suggest that this cognitive proximity relies on two fundamentals elements: on the one hand, valuing the patrimonial infrastructures of the territory; and on the other hand, rebuilding the territorial identity of the region. Then the local policies lean both on the values that underlie these elements and on rhetorical modalities, to impulse in-depth changes that would have been more difficult to implement from the usual political levers.Cet article étudie comment un développement régional cohérent nécessite la mobilisation de ressources cognitives partagées. Dans le cas étudié - la région Nord Pas-de-Calais, cette proximité cognitive se construit via les politiques locales, sur la base du référentiel de développement durable. Pour saisir la manière dont les collectivités de la région activent cette ressource, nous avons mobilisé les outils d'analyse textuelle sur une trentaine d'entretiens auprès des acteurs publics du développement durabe. Les résultats mis en évidence suggèrent que cette proximité cognitive repose sur deux éléments fondamentaux : d'une part la mise en valeur d'un patrimoine infrastructurel territorialisé, et d'autre part la reconstruction d'une identité territoriale. Les politiques locales prennent ainsi appui sur les valeurs qui sous-tendent ces éléments ainsi que sur des modalités rhétoriques, pour impulser en profondeur une dynamique de changement, plus malaisée à mettre en œuvre partir des outils politiques habituels
Evaluation of the Proximity of Singaporean Children’s Dietary Habits to Food-Based Dietary Guidelines
Dietary habits in children may not only impact current health status but could also shape future, lifelong dietary choices. Dietary intake data in Singaporean children are limited. The current study aimed to define the overall diet quality of Singaporean children using an existing cross-sectional dataset and to consider how demographic factors (i.e., body mass index (BMI) status, ethnicity, age, and sex) were associated with these scores. Existing, cross-sectional dietary data (n = 561 children aged 6–12 years, collected in 2014–2015) from duplicate 24-h recalls were assessed for diet quality using an index based on the Singaporean Health Promotion Board dietary guidelines. Total diet quality scores were calculated from ten different components (frequencies of rice and alternatives, whole grains, fruits, vegetables, meat and alternatives, dairy and alternatives, total fat, saturated fat, sodium intake, and added sugars). Association with demographic factors and BMI category was evaluated by one-way multivariate ANOVA (MANOVA) tests, with Bonferroni post hoc analyses. Median (interquartile range) total diet quality scores were 65.4 (57.1–73.0). Median scores for whole grains (0.0, 0.0–33.4), fruits (24.1, 0.0–65.3), vegetables (36.5, 10.4-89.8), and sodium (58.4, 0.0–100.0) intake were frequently sub-optimal. Children of Malay ethnic origin had statistically lower total diet quality scores ((55.3, 47.5–60.3) vs. other ethnic groups (combined median 65.4 (57.1, 73.0); p < 0.001). These findings highlight the need for continuing efforts to improve dietary intake in young Singaporeans and for longitudinal dietary monitoring in this group
The CAT Imaging Telescope for Very-High-Energy Gamma-Ray Astronomy
The CAT (Cherenkov Array at Themis) imaging telescope, equipped with a
very-high-definition camera (546 fast phototubes with 0.12 degrees spacing
surrounded by 54 larger tubes in two guard rings) started operation in Autumn
1996 on the site of the former solar plant Themis (France). Using the
atmospheric Cherenkov technique, it detects and identifies very high energy
gamma-rays in the range 250 GeV to a few tens of TeV. The instrument, which has
detected three sources (Crab nebula, Mrk 421 and Mrk 501), is described in
detail.Comment: 24 pages, 15 figures. submitted to Elsevier Preprin
Is the tetraneutron a bound dineutron-dineutron molecule?
In light of a new experiment which claims a positive identification, we
discuss the possible existence of the tetraneutron. We explore a novel model
based on a dineutron-dineutron molecule. We show that this model is not able to
explain the tetraneutron as a bound state, in agreement with other theoretical
models already discussed in the literature.Comment: 9 pages, 3 figures, J. Phys. G, in pres
Yukawa Unification and the Superpartner Mass Scale
Naturalness in supersymmetry (SUSY) is under siege by increasingly stringent
LHC constraints, but natural electroweak symmetry breaking still remains the
most powerful motivation for superpartner masses within experimental reach. If
naturalness is the wrong criterion then what determines the mass scale of the
superpartners? We motivate supersymmetry by (1) gauge coupling unification, (2)
dark matter, and (3) precision b-tau Yukawa unification. We show that for an
LSP that is a bino-Higgsino admixture, these three requirements lead to an
upper-bound on the stop and sbottom masses in the several TeV regime because
the threshold correction to the bottom mass at the superpartner scale is
required to have a particular size. For tan beta about 50, which is needed for
t-b-tau unification, the stops must be lighter than 2.8 TeV when A_t has the
opposite sign of the gluino mass, as is favored by renormalization group
scaling. For lower values of tan beta, the top and bottom squarks must be even
lighter. Yukawa unification plus dark matter implies that superpartners are
likely in reach of the LHC, after the upgrade to 14 (or 13) TeV, independent of
any considerations of naturalness. We present a model-independent, bottom-up
analysis of the SUSY parameter space that is simultaneously consistent with
Yukawa unification and the hint for m_h = 125 GeV. We study the flavor and dark
matter phenomenology that accompanies this Yukawa unification. A large portion
of the parameter space predicts that the branching fraction for B_s to mu^+
mu^- will be observed to be significantly lower than the SM value.Comment: 34 pages plus appendices, 20 figure
HIV Prevention in Care and Treatment Settings: Baseline Risk Behaviors among HIV Patients in Kenya, Namibia, and Tanzania.
HIV care and treatment settings provide an opportunity to reach people living with HIV/AIDS (PLHIV) with prevention messages and services. Population-based surveys in sub-Saharan Africa have identified HIV risk behaviors among PLHIV, yet data are limited regarding HIV risk behaviors of PLHIV in clinical care. This paper describes the baseline sociodemographic, HIV transmission risk behaviors, and clinical data of a study evaluating an HIV prevention intervention package for HIV care and treatment clinics in Africa. The study was a longitudinal group-randomized trial in 9 intervention clinics and 9 comparison clinics in Kenya, Namibia, and Tanzania (N = 3538). Baseline participants were mostly female, married, had less than a primary education, and were relatively recently diagnosed with HIV. Fifty-two percent of participants had a partner of negative or unknown status, 24% were not using condoms consistently, and 11% reported STI symptoms in the last 6 months. There were differences in demographic and HIV transmission risk variables by country, indicating the need to consider local context in designing studies and using caution when generalizing findings across African countries. Baseline data from this study indicate that participants were often engaging in HIV transmission risk behaviors, which supports the need for prevention with PLHIV (PwP). TRIAL REGISTRATION: ClinicalTrials.gov NCT01256463
Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up
Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated
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