918 research outputs found
The Heart Of Adult Peer-Group Learning: Living The Learning Together
The experience of learning in peer-groups has not been adequately studied. This researcher
used her own experience with 2 other graduate students for over 2 years as the basis for her dissertation. Various literatures, not previously linked were pulled together that shed light on this particular phenomenon. Qualitative analysis of her peer-group’s conversations produced 8 key themes. A synthesis of the literature and of the themes provides an overview of adult peer-group learning; summed up by the theme living the learning together
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
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
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
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
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
Sociological stalking? Methods, ethics and power in longitudinal criminological research
Scholarship on criminal careers and desistance from crime employing longitudinal
methodologies has paid scant attention to sociological and anthropological debates
regarding epistemology, reflexivity and researcher positionality. This is surprising in
light of a recent phenomenological turn in desistance research wherein (former)
lawbreakers’ identity, reflexivity, and self-understanding have become central
preoccupations. In this article I interrogate aspects of the methodological ‘underside’
(Gelsthorpe, 2007) of qualitative longitudinal research with criminalised women
through an examination of the surveillant position of the researcher. Focusing on
methods, ethics and power, I examine some contradictions of feminist concerns to
‘give women voice’ in research involving re-tracing an over-surveilled and highly
stigmatised population. I reflect on the effects of researcher positionality through a
conceptualisation of re-tracing methods as, at worst, a form of sociological stalking
A Comparison of the Forest Floras along the Des Moines and Missouri Rivers
A cursory examination of the deciduous forest of eastern North America, at intervals from its center (14) in the Ohio River basin westward, discloses changes in the structure of the forest characterized chiefly by a reduction in number of species and in the abundance and size of the component trees. Beyond the Mississippi river in Iowa and eastern Nebraska the forest flora is concentrated chiefly along streams flowing diagonally southeastward. Bordering these streams the deciduous forest extends into the prairie
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