203 research outputs found
Massive Decaying Tau Neutrino and Big Bang Nucleosynthesis
Comparing Big Bang Nucleosynthesis predictions with the light element
abundances inferred from observational data, we can obtain the strong
constraints on some neutrino properties, e.g. number of neutrino species, mass,
lifetime. Recently the deuterium abundances were measured in high red-shift QSO
absorption systems. It is expected that they are close to the primordial
values, however, two groups have reported inconsistent values which are
different in one order of magnitude. In this paper we show how we can constrain
on neutrino mass and its lifetime in each case when we adopt either high
or low deuterium data. We find that if 0.01 \sec
\lesssim \tau_{\nutau} \lesssim 1 \sec and 10\mev \lesssim m_{\nutau}
\lesssim 24\mev, the theoretical predictions agree with the low D/H
abundances. On the other hand if we adopt the high D/H abundances, we obtain
the upper bound of neutrino mass, m_{\nutau}\lesssim 20 \mev.Comment: 11 pages, using LATEX and four postscript figure
Comparison of Cyclic Nucloetide Phosphodiesterase in Physarum favicomum
We have studied both cyclic AMP phosphodiesterase and cyclic GMP phosphodiesterase in the myxomycete Physarum flavicomum. The cyclic AMP phosphodiesterase preparations were isolated from both the diploid plasmodial stage of the lifecycle and the haploid myxamoebal stage. The plasmodial enzyme was prepared from spent medium (extracellular) and also from purified nuclei. The myxamoebal enzyme was prepared from purified nuclei. Cyclic GMP phosphodiesterase activity was studied in purified nuclei isolated from the plasmodium. One unusual feature of all the enzymes from the plasmodium is extreme heat stability; they remain catalytically active even after exposure to a boiling water bath for twenty minutes. The myxamoebae enzyme lost all activity after five minutes in a boiling water bath. All four enzyme preparations gave linear product formation with time and all were inhibited by isobutyl-methyl xanthine, a potent competitive inhibitor of cyclic nucleotide phosphodiesterase
Mechanisms underlying divergent responses of genetically distinct macrophages to IL-4
Mechanisms by which noncoding genetic variation influences gene expression remain only partially understood but are considered to be major determinants of phenotypic diversity and disease risk. Here, we evaluated effects of >50 million single-nucleotide polymorphisms and short insertions/deletions provided by five inbred strains of mice on the responses of macrophages to interleukin-4 (IL-4), a cytokine that plays pleiotropic roles in immunity and tissue homeostasis. Of >600 genes induced >2-fold by IL-4 across the five strains, only 26 genes reached this threshold in all strains. By applying deep learning and motif mutation analyses to epigenetic data for macrophages from each strain, we identified the dominant combinations of lineage-determining and signal-dependent transcription factors driving IL-4 enhancer activation. These studies further revealed mechanisms by which noncoding genetic variation influences absolute levels of enhancer activity and their dynamic responses to IL-4, thereby contributing to strain-differential patterns of gene expression and phenotypic diversity
Big Bang Nucleosynthesis and Lepton Number Asymmetry in the Universe
Recently it is reported that there is the discrepancy between big bang
nucleosynthesis theory and observations (BBN crisis). We show that BBN
predictions agree with the primordial abundances of light elements, He4, D, He3
and Li7 inferred from the observational data if an electron neutrino has a net
chemical potential xi_{nu_e} due to lepton asymmetry. We estimate that
xi_{nu_e} = 0.043^{+0.040}_{-0.040} (95% C.L.) and Omega_bh^2 =
0.015^{+0.006}_{-0.003} (95% C.L.).Comment: 10 pages, using AAS LATEX and three postscript figure
Superheavy Dark Matter and Thermal Inflation
The thermal inflation is the most plausible mechanism that solves the
cosmological moduli problem naturally. We discuss relic abundance of superheavy
particle in the presence of the thermal inflation assuming that its
lifetime is longer than the age of the universe, and show that the long-lived
particle of mass -- GeV may form a part of the dark
matter in the present universe in a wide region of parameter space of the
thermal inflation model. The superheavy dark matter of mass GeV
may be interesting in particular, since its decay may account for the observed
ultra high-energy cosmic rays if the lifetime of the particle is
sufficiently long.Comment: 13 pages (RevTex file) including 8 figures, revised version to be
published in Physical Review
RNAseq Analyses Identify Tumor Necrosis Factor-Mediated Inflammation as a Major Abnormality in ALS Spinal Cord
ALS is a rapidly progressive, devastating neurodegenerative illness of adults that produces disabling weakness and spasticity arising from death of lower and upper motor neurons. No meaningful therapies exist to slow ALS progression, and molecular insights into pathogenesis and progression are sorely needed. In that context, we used high-depth, next generation RNA sequencing (RNAseq, Illumina) to define gene network abnormalities in RNA samples depleted of rRNA and isolated from cervical spinal cord sections of 7 ALS and 8 CTL samples. We aligned \u3e50 million 2X150 bp paired-end sequences/sample to the hg19 human genome and applied three different algorithms (Cuffdiff2, DEseq2, EdgeR) for identification of differentially expressed genes (DEG’s). Ingenuity Pathways Analysis (IPA) and Weighted Gene Co-expression Network Analysis (WGCNA) identified inflammatory processes as significantly elevated in our ALS samples, with tumor necrosis factor (TNF) found to be a major pathway regulator (IPA) and TNFα-induced protein 2 (TNFAIP2) as a major network “hub” gene (WGCNA). Using the oPOSSUM algorithm, we analyzed transcription factors (TF) controlling expression of the nine DEG/hub genes in the ALS samples and identified TF’s involved in inflammation (NFkB, REL, NFkB1) and macrophage function (NR1H2::RXRA heterodimer). Transient expression in human iPSC-derived motor neurons of TNFAIP2 (also a DEG identified by all three algorithms) reduced cell viability and induced caspase 3/7 activation. Using high-density RNAseq, multiple algorithms for DEG identification, and an unsupervised gene co-expression network approach, we identified significant elevation of inflammatory processes in ALS spinal cord with TNF as a major regulatory molecule. Overexpression of the DEG TNFAIP2 in human motor neurons, the population most vulnerable to die in ALS, increased cell death and caspase 3/7 activation. We propose that therapies targeted to reduce inflammatory TNFα signaling may be helpful in ALS patients
SALL1 enforces microglia-specific DNA binding and function of SMADs to establish microglia identity
Spalt-like transcription factor 1 (SALL1) is a critical regulator of organogenesis and microglia identity. Here we demonstrate that disruption of a conserved microglia-specific super-enhancer interacting with the Sall1 promoter results in complete and specific loss of Sall1 expression in microglia. By determining the genomic binding sites of SALL1 and leveraging Sall1 enhancer knockout mice, we provide evidence for functional interactions between SALL1 and SMAD4 required for microglia-specific gene expression. SMAD4 binds directly to the Sall1 super-enhancer and is required for Sall1 expression, consistent with an evolutionarily conserved requirement of the TGFβ and SMAD homologs Dpp and Mad for cell-specific expression of Spalt in the Drosophila wing. Unexpectedly, SALL1 in turn promotes binding and function of SMAD4 at microglia-specific enhancers while simultaneously suppressing binding of SMAD4 to enhancers of genes that become inappropriately activated in enhancer knockout microglia, thereby enforcing microglia-specific functions of the TGFβ–SMAD signaling axis.</p
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Globalisation and MA TESOL programs in the UK
This article reports the results of a mixed-methods approach to investigating the association between globalisation and MATESOL in UK universities. Qualitative and quantitative data collected from academic staff through eight emails, four interviews and 41 questionnaires indicate that the globalised context of higher education have affected these programmes in a number of ways including an increasing interest in recruiting more international students and a growing awareness about the need for curriculum and content modifications. The analysis of the data suggests that although change has been an inherent characteristic of these MAs over the past decade, it has been implemented gradually and conservatively, often relying on a dialectic relationship between academic staff and universities’ policies. The results imply that factors other than globalisation have also been at work. Many of the participants contend that globalisation has not lowered the quality of these MAs or standards of good practice
Expression and Function of Serotonin 2A and 2B Receptors in the Mammalian Respiratory Network
Neurons of the respiratory network in the lower brainstem express a variety of serotonin receptors (5-HTRs) that act primarily through adenylyl cyclase. However, there is one receptor family including 5-HT2A, 5-HT2B, and 5-HT2C receptors that are directed towards protein kinase C (PKC). In contrast to 5-HT2ARs, expression and function of 5-HT2BRs within the respiratory network are still unclear. 5-HT2BR utilizes a Gq-mediated signaling cascade involving calcium and leading to activation of phospholipase C and IP3/DAG pathways. Based on previous studies, this signal pathway appears to mediate excitatory actions on respiration. In the present study, we analyzed receptor expression in pontine and medullary regions of the respiratory network both at the transcriptional and translational level using quantitative RT-PCR and self-made as well as commercially available antibodies, respectively. In addition we measured effects of selective agonists and antagonists for 5-HT2ARs and 5-HT2BRs given intra-arterially on phrenic nerve discharges in juvenile rats using the perfused brainstem preparation. The drugs caused significant changes in discharge activity. Co-administration of both agonists revealed a dominance of the 5-HT2BR. Given the nature of the signaling pathways, we investigated whether intracellular calcium may explain effects observed in the respiratory network. Taken together, the results of this study suggest a significant role of both receptors in respiratory network modulation
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