4,655 research outputs found
On the Higgs Mass in the CMSSM
We estimate the mass of the lightest neutral Higgs boson h in the minimal
supersymmetric extension of the Standard Model with universal soft
supersymmetry-breaking masses (CMSSM), subject to the available accelerator and
astrophysical constraints. For m_t = 174.3 GeV, we find that 114 GeV < m_h <
127 GeV and a peak in the tan beta distribution simeq 55. We observe two
distinct peaks in the distribution of m_h values, corresponding to two
different regions of the CMSSM parameter space. Values of m_h < 119 GeV
correspond to small values of the gaugino mass m_{1/2} and the soft trilinear
supersymmetry-breaking parameter A_0, lying along coannihilation strips, and
most of the allowed parameter sets are consistent with a supersymmetric
interpretation of the possibly discrepancy in g_mu - 2. On the other hand,
values of m_h > 119 GeV may correspond to much larger values of m_{1/2} and
A_0, lying in rapid-annihilation funnels. The favoured ranges of m_h vary with
m_t, the two peaks being more clearly separated for m_t = 178 GeV and merging
for m_t = 172.7 GeV. If the g_mu - 2 constraint is imposed, the mode of the m_h
distribution is quite stable, being sim 117 GeV for all the studied values of
m_t.Comment: 14 pages, 12 figure
Morphological Evolution of Distant Galaxies from Adaptive Optics Imaging
We report here on a sample of resolved, infrared images of galaxies at z~0.5
taken with the 10-m Keck Telescope's Adaptive Optics (AO) system. We regularly
achieve a spatial resolution of 0.05'' and are thus able to resolve both the
disk and bulge components. We have extracted morphological information for ten
galaxies and compared their properties to those of a local sample. The
selection effects of both samples were explicitly taken into account in order
to derive the unbiased result that disks at z~0.5 are ~0.6 mag arcsec^-2
brighter than, and about the same size as, local disks. The
no-luminosity-evolution case is ruled out at 90% confidence. We also find, in a
more qualitative analysis, that the bulges of these galaxies have undergone a
smaller amount of surface brightness evolution and have also not changed
significantly in size from z~0.5 to today. This is the first time this type of
morphological evolution has been measured in the infrared and it points to the
unique power of AO in exploring galaxy evolution.Comment: 27 pages, 7figures, 2 tables. Accepted for publication in the
Astrophysical Journa
HST/WFPC2 morphologies and color maps of distant luminous infrared galaxies
Using HST/WFPC2 imaging in F606W (or F450W) and F814W filters, we obtained
the color maps in observed frame for 36 distant (0.4<z<1.2) luminous infrared
galaxies (LIRGs), with average star formation rates of ~100 M_sun/yr. Stars and
compact sources are taken as references to align images after correction of
geometric distortion. This leads to an alignment accuracy of 0.15 pixel, which
is a prerequisite for studying the detailed color properties of galaxies with
complex morphologies. A new method is developed to quantify the reliability of
each pixel in the color map without any bias against very red or blue color
regions.Based on analyses of two-dimensional structure and spatially resolved
color distribution, we carried out morphological classification for LIRGs.
About 36% of the LIRGs were classified as disk galaxies and 22% as irregulars.
Only 6 (17%) systems are obvious ongoing major mergers. An upper limit of 58%
was found for the fraction of mergers in LIRGs with all the possible
merging/interacting systems included. Strikingly, the fraction of compact
sources is as high as 25%, similar to that found in optically selected samples.
From their K band luminosities, LIRGs are relatively massive systems, with an
average stellar mass of about 1.1x10^11 solar mass. They are related to the
formation of massive and large disks, from their morphologies and also from the
fact that they represent a significant fraction of distant disks selected by
their sizes. The compact LIRGs show blue cores, which could be associated with
the formation of the central region of these galaxies. We suggest that there
are many massive disks still forming a large fraction of their stellar mass
since z=1. For most of them, their central parts (bulge?) were formed prior to
the formation of their disks.Comment: 20 pages, 14 figures, accepted for publication in A&
Establishing the Fluency Gap Between Native and Non-Native-Speech
Although various dimensions of speech fluency have so far generated a great deal of research interest, very few accounts have tackled the issue of the relationship between L1 and L2 fluency. Also, little empirical evidence has been provided to support the claim that language users are more fluent in their mother tongue than in a foreign/second language. This study examines the fluency gap between L1 and L2 fluency using a battery of objectively quantifiable temporal measures of speed and breakdown fluency. It also attempts to identify those temporal fluency variables which are affected by the individual way of speaking rather than the degree of automatisation of speech processing and which underlie oral performance both in L1 and L2. The analysis draws on transcriptions of elicited speech samples in L1 (Polish) and L2 (English)
Effects of low testosterone levels and of adrenal androgens on growth of prostate tumor models in nude mice
Abstract
Two transplantable, androgen dependent prostate tumor models of human origin, PC-82 and PC-EW, were used to study the effect of low androgen levels and adrenal androgens on prostate tumor cell proliferation. Tumor load of the PC-82 and PC-EW tumors could be maintained constant when plasma testosterone levels were 0.8 and 0.9 nmol/l, respectively, corresponding with an intratissue 5α-dihydrotestosterone level of 3–4 pmol/g tissue. This critical androgen level for prostate tumor growth stimulation amounted to 2–3 times the castration level and proved to be similar for both tumor models. Relatively high levels of androstenedione resulted in physiological levels of plasma testosterone causing androgen concentrations in PC-82 tumor tissue exceeding the critical level for tumor growth. These results indicate that submaximal suppression of androgens can stop tumor growth in these prostate tumor models
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Development of speech fluency over a short period of time: effects of pedagogic intervention
This study investigates the effects of a short-term pedagogic intervention on the development of L2 fluency among learners studying English for Academic purposes (EAP) at a university in the UK. It also examines the interaction between the development of fluency, and complexity and accuracy. Through a pre-test, post-test design, data were collected over a period of four weeks from learners performing monologic tasks. While the Control Group (CG) focused on developing general speaking and listening skills, the Experimental Group (EG) received awareness-raising activities and fluency strategy training in addition to general speaking and listening practice i.e following the syllabus. The data, coded in terms of a range of measures of fluency, accuracy and complexity, were subjected to repeated measures MANOVA, t-tests and correlations. The results indicate that after the intervention, while some fluency gains were achieved by the CG, the EG produced statistically more fluent language demonstrating a faster speech and articulation rate, longer runs and higher phonation time ratios. The significant correlations obtained between measures of accuracy and learners’ pauses in the CG suggest that pausing opportunities may have been linked to accuracy. The findings of the study have significant implications for L2 pedagogy, highlighting the effective impact of instruction on the development of fluency
Protein levels and colony development of Africanized and European honey bees fed natural and artificial diets
Pollen substitute diets are a valuable resource for maintaining strong and health honey bee colonies. Specific diets may be useful in one region or country and inadequate or economically unviable in others. We compared two artificial protein diets that had been formulated from locally-available ingredients in Brazil with bee bread and a non-protein sucrose diet. Groups of 100 newly-emerged, adult workers of Africanized honey bees in Brazil and European honey bees in the USA were confined in small cages and fed on one of four diets for seven days. The artificial diets included a high protein diet made of soy milk powder and albumin, and a lower protein level diet consisting of soy milk powder, brewer’s yeast and rice bran. The initial protein levels in newly emerged bees were approximately 18-21 μg/μL hemolymph. After feeding on the diets for seven days, the protein levels in the hemolymph were similar among the protein diet groups (~37-49 μg/μL after seven days), although Africanized bees acquired higher protein levels, increasing 145 and 100% on diets D1 and D2, respectively, versus 83 and 60% in the European bees. All the protein diets resulted in significantly higher levels of protein than sucrose solution alone. In the field, the two pollen substitute diets were tested during periods of low pollen availability in the field in two regions of Brazil. Food consumption, population development, colony weight, and honey production were evaluated to determine the impact of the diets on colony strength parameters. The colonies fed artificial diets had a significant improvement in all parameters, while control colonies dwindled during the dearth period. We conclude that these two artificial protein diets have good potential as pollen substitutes during dearth periods and that Africanized bees more efficiently utilize artificial protein diets than do European honey bees.FAPESP 07/07701-3FAPESP 04/15801-0CNPqFAEP
Uptake of thyroxine in cultured anterior pituitary cells of euthyroid rats
The uptake of [125I]T4 was investigated in cultured anterior pituitary
cells isolated from adult fed Wistar rats and cultured for 3 days in
medium containing 10% fetal calf serum. Experiments were performed with
[125I]T4 (10(5) to 2 x 10(6) cpm; 0.35-7 nM) in medium containing 0.5% or
0.1% BSA. The uptake of [125I]T4 increased with time and showed
equilibrium after around 1 h of incubation. The presence of 10 microM
unlabeled T4 during incubation decreased the uptake of [125I]T4 by 65-70%
at all time intervals. After 24 h of incubation, 1.5% iodide and 3.2%
conjugates were detected in the medium, whereas around 20% of cellular
radioactivity represented [125I]T3. The 15-min uptake of [125I]T4 was
significantly reduced by simultaneous incubation with 100 nM T4 (by 24%; P
< 0.05), 100 nM T3 (by 38%; P < 0.001), or 10 microM rT3 (by 32%; P <
0.001), whereas 10 microM tetraiodothyroacetic acid (Tetrac) had no
effect. Furthermore, preincubation (30 min) and incubation (15 min) with
10 microM monodansylcadaverine, oligomycin, or monensin reduced the uptake
of [125I]T4 by 30%, 50%, and 40%, respectively (all P < 0.001).
Substitution of Na+ in the buffer by K+ diminished the uptake of [125I]T4
by 39% (P < 0.005); 2 mM phenylalanine, tyrosine, or tryptophan reduced
[125I]T4 uptake by 18% (P < 0.05), 18% (P = NS), and 33% (P < 0.005),
respectively. Our data suggest that the pituitary contains a specific
carrier-mediated energy-requiring mechanism for [125I]T4 uptake that is
partly dependent on the Na+ gradient. In addition, part of [125I]T4 uptake
in the pituitary might occur through an amino acid transport system. When
expressed per pM of free hormone, the 15-min uptake of [125I]T4 was
approximately as high as that of [125I]T3. Because the reduction of
[125I]T4 uptake by T4, T3, monodansylcadaverine, oligomycin, and monensin
was roughly the same as the previously reported reduction of [125I]T3
uptake by the same compounds, it is further suggested that T4 and T3 share
a common carrier in cultured anterior pituitary cells
The course of cytokine and chemokine gene expression in clinically suspect arthralgia patients during progression to inflammatory arthritis
Objectives: Autoantibody responses increase years before the onset of inflammatory arthritis (IA) and are stable during transitioning from clinically suspect arthralgia (CSA) to IA. Cytokine and chemokine levels also increase years before IA onset. However, the course in the at-risk stage of CSA during progression to disease or non-progression is unknown. To increase the understanding of processes mediating disease development, we studied the course of cytokine, chemokine and related receptors gene expression in CSA patients during progression to IA and in CSA patients who ultimately did not develop IA. Methods: Whole-blood RNA expression of 37 inflammatory cytokines, chemokines and related receptors was determined by dual-colour reverse transcription multiplex ligation-dependent probe amplification in paired samples of CSA patients at CSA onset and either at IA development or after 24 months without IA development. ACPA-positive and ACPA-negative CSA patients developing IA were compared at CSA onset and during progression to IA. Generalised estimating equations tested changes over time. A false discovery rate approach was applied. Results: None of the cytokine/chemokine genes significantly changed in expression between CSA onset and IA development. In CSA patients without IA development, G-CSF expression decreased (P = 0.001), whereas CCR6 and TNIP1 expression increased (P < 0.001 and P = 0.002, respectively) over a 2 year period. Expression levels in ACPA-positive and ACPA-negative CSA patients who developed IA were similar. Conclusion: Whole-blood gene expression of assessed cytokines, chemokines and related receptors did not change significantly from CSA to IA development. This suggests that changes in expression of these molecules may not be related to the final process of developing chronicity and may have occurred preceding CSA onset. Changes in gene expression in CSA patients without IA development may provide clues for processes related to resolution.</p
Uptake of triiodothyroacetic acid and its effect on thyrotropin secretion in cultured anterior pituitary cells
The uptake of [125I]triiodothyroacetic acid ([125I]Triac) in anterior
pituitary cells was investigated and compared with that of [125I]T3.
Furthermore, the effects of Triac, T3, and T4 on TSH release were
compared. Cells isolated from adult male Wistar rats were cultured for 3
days in medium with 10% fetal calf serum. Uptake was measured at 37 C with
[125I]Triac (100,000 cpm; 120 pM) or [125I]T3 (50,000 cpm; 50 pM) in
medium with 0.5% BSA. In this medium, the ratio of the free fractions of
Triac, T3, and T4 was 1:8:1. Exposure of cells to 100 nM TRH for 2 h
stimulated TSH release by 80-110% (P < 0.001). Comparing total hormone
levels (1 nM to 1 microM), Triac and T3 were equally effective in reducing
this response, and both were 10-fold more effective than T4. The time
course (15 min to 4 h) of [125I]Triac uptake was similar to that of
[125I]T3, showing equilibrium after 1 h. Unlabeled Triac (1 microM)
reduced the uptake of [125I]Triac and [125I]T3 at all time intervals.
Expressed per pM free hormone, the cellular and nuclear uptake of
[125I]Triac were twice those of [125I]T3. The 15-min uptake of [125I]Triac
was reduced by incubation with 10 nM unlabeled Triac (35%; P < 0.001).
Maximum inhibition (56%; P < 0.001) was found with 10 microM Triac. A
similar effect was seen with 10 microM T3, T4, or
3,3',5,5'-tetraiodothyroacetic acid. Preincubation (30 min) and incubation
(15 min) with 10 microM oligomycin reduced the cellular ATP content by 51%
(P < 0.001), [125I]T3 uptake by 77% (P < 0.001), and [125I]Triac uptake by
only 25% (P < 0.001). The temperature dependence of [125I]Triac and
[125I]T3 uptake was the same. Preincubation and incubation with 10 microM
monensin (reduces the Na+ gradient) or 10 microM monodansylcadaverine
(inhibits receptor-mediated endocytosis) reduced 15-min [125I] Triac
uptake by 15% (P < 0.005) and 19% (P < 0.005), respectively. The data show
that 1) Triac, on the basis of the free hormone concentration, is more
potent than T3 or T4 in suppressing TSH secretion; and 2) the rapid uptake
of [125I]Triac by the anterior pituitary occurs by a carrier-mediated
mechanism that is only partially dependent on ATP or the Na+ gradient
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