279 research outputs found
CMB Anisotropy from Baryogenesis by a Scalar Field
We study the cosmic microwave background (CMB) anisotropy in the scenario
where the baryon asymmetry of the universe is generated from a condensation of
a scalar field. In such a scenario, the scalar condensation may acquire
fluctuation during the inflation which becomes a new source of the cosmic
density perturbations. In particular, the primordial fluctuation of the scalar
condensation may induce correlated mixture of the adiabatic and isocurvature
fluctuations. If the scalar condensation decays before it completely dominates
the universe, the CMB angular power spectrum may significantly deviate from the
conventional adiabatic result. Such a deviation may be observed in the on-going
MAP experiment.Comment: 14 pages, 3 figure
Impaired Interoceptive Accuracy in Semantic Variant Primary Progressive Aphasia
Background: Interoception (the perception of internal bodily sensations) is strongly linked to emotional experience and sensitivity to the emotions of others in healthy subjects. Interoceptive impairment may contribute to the profound socioemotional symptoms that characterize frontotemporal dementia (FTD) syndromes, but remains poorly defined.
Methods: Patients representing all major FTD syndromes and healthy age-matched controls performed a heartbeat counting task as a measure of interoceptive accuracy. In addition, patients had volumetric MRI for voxel-based morphometric analysis, and their caregivers completed a questionnaire assessing patients’ daily-life sensitivity to the emotions of others.
Results: Interoceptive accuracy was impaired in patients with semantic variant primary progressive aphasia relative to healthy age-matched individuals, but not in behavioral variant frontotemporal dementia and nonfluent variant primary progressive aphasia. Impaired interoceptive accuracy correlated with reduced daily-life emotional sensitivity across the patient cohort, and with atrophy of right insula, cingulate, and amygdala on voxel-based morphometry in the impaired semantic variant group, delineating a network previously shown to support interoceptive processing in the healthy brain.
Conclusion: Interoception is a promising novel paradigm for defining mechanisms of reduced emotional reactivity, empathy, and self-awareness in neurodegenerative syndromes and may yield objective measures for these complex symptoms
Complete constraints on a nonminimally coupled chaotic inflationary scenario from the cosmic microwave background
We present complete constraints imposed from observations of the cosmic
microwave background radiation (CMBR) on the chaotic inflationary scenario with
a nonminimally coupled inflaton field proposed by Fakir and Unruh (FU). Our
constraints are complete in the sense that we investigate both the scalar
density perturbation and the tensor gravitational wave in the Jordan frame, as
well as in the Einstein frame. This makes the constraints extremely strong
without any ambiguities due to the choice of frames. We find that the FU
scenario generates tiny tensor contributions to the CMBR relative to chaotic
models in minimal coupling theory, in spite of its spectral index of scalar
perturbation being slightly tilted. This means that the FU scenario will be
excluded if any tensor contributions to CMBR are detected by the forthcoming
satellite missions. Conversely, if no tensor nature is detected despite the
tilted spectrum, a minimal chaotic scenario will be hard to explain and the FU
scenario will be supported.Comment: 7 pages, no figure, RevTeX, to appear in Phys.Rev. D59 (Mar. 15,
1999
The Cosmology of Asymmetric Brane Modified Gravity
We consider the asymmetric branes model of modified gravity, which can
produce late time acceleration of the universe and compare the cosmology of
this model to the standard CDM model and to the DGP braneworld model.
We show how the asymmetric cosmology at relevant physical scales can be
regarded as a one-parameter extension of the DGP model, and investigate the
effect of this additional parameter on the expansion history of the universe.Comment: 21 pages, 9 figures, journal versio
The degradation of p53 and its major E3 ligase Mdm2 is differentially dependent on the proteasomal ubiquitin receptor S5a.
p53 and its major E3 ligase Mdm2 are both ubiquitinated and targeted to the proteasome for degradation. Despite the importance of this in regulating the p53 pathway, little is known about the mechanisms of proteasomal recognition of ubiquitinated p53 and Mdm2. In this study, we show that knockdown of the proteasomal ubiquitin receptor S5a/PSMD4/Rpn10 inhibits p53 protein degradation and results in the accumulation of ubiquitinated p53. Overexpression of a dominant-negative deletion of S5a lacking its ubiquitin-interacting motifs (UIM)s, but which can be incorporated into the proteasome, also causes the stabilization of p53. Furthermore, small-interferring RNA (siRNA) rescue experiments confirm that the UIMs of S5a are required for the maintenance of low p53 levels. These observations indicate that S5a participates in the recognition of ubiquitinated p53 by the proteasome. In contrast, targeting S5a has no effect on the rate of degradation of Mdm2, indicating that proteasomal recognition of Mdm2 can be mediated by an S5a-independent pathway. S5a knockdown results in an increase in the transcriptional activity of p53. The selective stabilization of p53 and not Mdm2 provides a mechanism for p53 activation. Depletion of S5a causes a p53-dependent decrease in cell proliferation, demonstrating that p53 can have a dominant role in the response to targeting S5a. This study provides evidence for alternative pathways of proteasomal recognition of p53 and Mdm2. Differences in recognition by the proteasome could provide a means to modulate the relative stability of p53 and Mdm2 in response to cellular signals. In addition, they could be exploited for p53-activating therapies. This work shows that the degradation of proteins by the proteasome can be selectively dependent on S5a in human cells, and that this selectivity can extend to an E3 ubiquitin ligase and its substrate
Current evidence for a modulation of low back pain by human genetic variants
The manifestation of chronic back pain depends on structural, psychosocial, occupational and genetic influences. Heritability estimates for back pain range from 30% to 45%. Genetic influences are caused by genes affecting intervertebral disc degeneration or the immune response and genes involved in pain perception, signalling and psychological processing. This inter-individual variability which is partly due to genetic differences would require an individualized pain management to prevent the transition from acute to chronic back pain or improve the outcome. The genetic profile may help to define patients at high risk for chronic pain. We summarize genetic factors that (i) impact on intervertebral disc stability, namely Collagen IX, COL9A3, COL11A1, COL11A2, COL1A1, aggrecan (AGAN), cartilage intermediate layer protein, vitamin D receptor, metalloproteinsase-3 (MMP3), MMP9, and thrombospondin-2, (ii) modify inflammation, namely interleukin-1 (IL-1) locus genes and IL-6 and (iii) and pain signalling namely guanine triphosphate (GTP) cyclohydrolase 1, catechol-O-methyltransferase, ÎĽ opioid receptor (OPMR1), melanocortin 1 receptor (MC1R), transient receptor potential channel A1 and fatty acid amide hydrolase and analgesic drug metabolism (cytochrome P450 [CYP]2D6, CYP2C9)
Accelerating cosmologies tested by distance measures
We test if the latest Gold set of 182 SNIa or the combined "Platinum" set of
192 SNIa from the ESSENCE and Gold sets, in conjunction with the CMB shift
parameter show a preference between the LambdaCDM model, three wCDM models, and
the DGP model of modified gravity as an explanation for the current
accelerating phase of the universe's expansion. We consider flat wCDM models
with an equation of state w(a) that is (i) constant with scale factor , (ii)
varies as w(a)=w_0+w_a(1-a) for redshifts probed by supernovae but is fixed at
-1 at earlier epochs and (iii) varies as w_0+w_a(1-a) since recombination. We
find that all five models explain the data with comparable success.Comment: 15 pages, 7 figures, 1 table. New ESSENCE SN data include
Observing the Evolution of the Universe
How did the universe evolve? The fine angular scale (l>1000) temperature and
polarization anisotropies in the CMB are a Rosetta stone for understanding the
evolution of the universe. Through detailed measurements one may address
everything from the physics of the birth of the universe to the history of star
formation and the process by which galaxies formed. One may in addition track
the evolution of the dark energy and discover the net neutrino mass.
We are at the dawn of a new era in which hundreds of square degrees of sky
can be mapped with arcminute resolution and sensitivities measured in
microKelvin. Acquiring these data requires the use of special purpose
telescopes such as the Atacama Cosmology Telescope (ACT), located in Chile, and
the South Pole Telescope (SPT). These new telescopes are outfitted with a new
generation of custom mm-wave kilo-pixel arrays. Additional instruments are in
the planning stages.Comment: Science White Paper submitted to the US Astro2010 Decadal Survey.
Full list of 177 author available at http://cmbpol.uchicago.ed
Testing the DGP model with ESSENCE
We use the recent supernova data set from the ESSENCE collaboration combined
with data from the Supernova Legacy Survey and nearby supernovae to test the
DGP brane world model and its generalisations. Combination of this data with a
flatness prior and the position of the peak of the CMB disfavours the DGP model
slightly. Inclusion of the baryon acoustic peak from the Sloan Digital Sky
Survey increase the tension of the DGP model with the data, although it is not
clear how self consistent this procedure would be without a re-analysis of the
survey data in the framework of the DGP cosmology. Generalisations of the DGP
model are tested and constraints on relevant parameters obtained.Comment: Minor corrections, clarifications and references added. Published in
JCA
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