958 research outputs found
Adsorption-induced conversion of the carbon nanotube field effect transistor from ambipolar to unipolar behavior
We investigate ambipolar to unipolar transition by the effect of ambient air on the carbon nanotube field-effect transistor. A unipolar transport property of the double-walled nanotube field-effect transistor and its conversion from ambipolar behavior are observed. We suggest that adsorptions of oxygen molecules, whose lowest-unoccupied-molecular-orbital state is around the midgap of the carbon nanotube, could suppress the electron channel formation and, consequently, result in the unipolar transport behavior.open343
Light Higgsino from Axion Dark Radiation
The recent observations imply that there is an extra relativistic degree of
freedom coined dark radiation. We argue that the QCD axion is a plausible
candidate for the dark radiation, not only because of its extremely small mass,
but also because in the supersymmetric extension of the Peccei-Quinn mechanism
the saxion tends to dominate the Universe and decays into axions with a sizable
branching fraction. We show that the Higgsino mixing parameter mu is bounded
from above when the axions produced at the saxion decays constitute the dark
radiation: mu \lesssim 300 GeV for a saxion lighter than 2m_W, and mu less than
the saxion mass otherwise. Interestingly, the Higgsino can be light enough to
be within the reach of LHC and/or ILC even when the other superparticles are
heavy with mass about 1 TeV or higher. We also estimate the abundance of axino
produced by the decays of Higgsino and saxion.Comment: 18 pages, 1 figure; published in JHE
Interplay of Mre11 Nuclease with Dna2 plus Sgs1 in Rad51-Dependent Recombinational Repair
The Mre11/Rad50/Xrs2 complex initiates IR repair by binding to the end of a double-strand break, resulting in 5′ to 3′ exonuclease degradation creating a single-stranded 3′ overhang competent for strand invasion into the unbroken chromosome. The nuclease(s) involved are not well understood. Mre11 encodes a nuclease, but it has 3′ to 5′, rather than 5′ to 3′ activity. Furthermore, mutations that inactivate only the nuclease activity of Mre11 but not its other repair functions, mre11-D56N and mre11-H125N, are resistant to IR. This suggests that another nuclease can catalyze 5′ to 3′ degradation. One candidate nuclease that has not been tested to date because it is encoded by an essential gene is the Dna2 helicase/nuclease. We recently reported the ability to suppress the lethality of a dna2Δ with a pif1Δ. The dna2Δ pif1Δ mutant is IR-resistant. We have determined that dna2Δ pif1Δ mre11-D56N and dna2Δ pif1Δ mre11-H125N strains are equally as sensitive to IR as mre11Δ strains, suggesting that in the absence of Dna2, Mre11 nuclease carries out repair. The dna2Δ pif1Δ mre11-D56N triple mutant is complemented by plasmids expressing Mre11, Dna2 or dna2K1080E, a mutant with defective helicase and functional nuclease, demonstrating that the nuclease of Dna2 compensates for the absence of Mre11 nuclease in IR repair, presumably in 5′ to 3′ degradation at DSB ends. We further show that sgs1Δ mre11-H125N, but not sgs1Δ, is very sensitive to IR, implicating the Sgs1 helicase in the Dna2-mediated pathway
Differential Regulation of the Period Genes in Striatal Regions following Cocaine Exposure
Several studies have suggested that disruptions in circadian rhythms contribute to the pathophysiology of multiple psychiatric diseases, including drug addiction. In fact, a number of the genes involved in the regulation of circadian rhythms are also involved in modulating the reward value for drugs of abuse, like cocaine. Thus, we wanted to determine the effects of chronic cocaine on the expression of several circadian genes in the Nucleus Accumbens (NAc) and Caudate Putamen (CP), regions of the brain known to be involved in the behavioral responses to drugs of abuse. Moreover, we wanted to explore the mechanism by which these genes are regulated following cocaine exposure. Here we find that after repeated cocaine exposure, expression of the Period (Per) genes and Neuronal PAS Domain Protein 2 (Npas2) are elevated, in a somewhat regionally selective fashion. Moreover, NPAS2 (but not CLOCK (Circadian Locomotor Output Cycles Kaput)) protein binding at Per gene promoters was enhanced following cocaine treatment. Mice lacking a functional Npas2 gene failed to exhibit any induction of Per gene expression after cocaine, suggesting that NPAS2 is necessary for this cocaine-induced regulation. Examination of Per gene and Npas2 expression over twenty-four hours identified changes in diurnal rhythmicity of these genes following chronic cocaine, which were regionally specific. Taken together, these studies point to selective disruptions in Per gene rhythmicity in striatial regions following chronic cocaine treatment, which are mediated primarily by NPAS2. © 2013 Falcon et al
Affleck-Dine leptogenesis with varying Peccei-Quinn scale
The Affleck-Dine leptogenesis scenario along the LHu flat direction is reconsidered. It is known that successful Affleck-Dine leptogenesis requires that the lightest neutrino mass is extremely small. This situation can be significantly relaxed if the neutrino mass in the early universe is different from the present one. We consider a supersymmetric Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) type model, which provides a solution to the strong CP problem and generates a SUSY μ-term and right-handed neutrino masses. If the PQ scale during lepton number generation is much larger than the present value, leptogenesis is very efficient so that enough baryon number can be generated without introducing a hierarchically small neutrino mass. The final baryon asymmetry is related to the μ-term, and hence linked to the level of electroweak fine-tuning. We also show the PQ breaking scalar dynamics that keeps a large PQ breaking scale during inflation and lepton number generation. The μ-term generating superpotential plays an important role for preserving the lepton asymmetry during saxion oscillation. In this scenario, the axion isocurvature perturbation is naturally suppressed. © 2017, The Author(s)1111Nsciescopu
Ecology and technological capability of lactic acid bacteria isolated during Grillo grape vinification in the Marsala production area.
Grapes of “Grillo” variety, used to produce Marsala wine, were harvested from five vineyards different for climatic and agronomic parameters, in order to obtain a first mapping of lactic acid bacteria (LAB) inhabiting the production area. Marsala base wine production was followed at large-scale and two experimental vinifications, different for lysozyme and SO2 concentration and combination, were carried out at pilot-plant scale. LAB communities and conventional chemical parameters were periodically analysed. LAB were found on grapes at an average concentration of about 102 CFU g-1 which decreased during the transformation process. A total of 146 colonies were collected, but only 35 were recognized as presumptive LAB. On the basis of phenotypic differences and isolation source, 16 isolates were then subjected to genotypic identification and gathered into the following species: Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Enterococcus faecium, Leuconostoc fallax and Sporalactobacillus nakayamae subsp. nakayamae. Lactococcus lactis subsp. lactis strains was the species most frequently isolated during winemaking showing the highest resistance to SO2 and lysozyme
Heritability estimates of the Big Five personality traits based on common genetic variants
According to twin studies, the Big Five personality traits have substantial heritable components explaining 40–60% of the variance, but identification of associated genetic variants has remained elusive. Consequently, knowledge regarding the molecular genetic architecture of personality and to what extent it is shared across the different personality traits is limited. Using genomic-relatedness-matrix residual maximum likelihood analysis (GREML), we here estimated the heritability of the Big Five personality factors (extraversion, agreeableness, conscientiousness, neuroticism and openness for experience) in a sample of 5011 European adults from 527 469 single-nucleotide polymorphisms across the genome. We tested for the heritability of each personality trait, as well as for the genetic overlap between the personality factors. We found significant and substantial heritability estimates for neuroticism (15%, s.e.=0.08, P=0.04) and openness (21%, s.e.=0.08, P<0.01), but not for extraversion, agreeableness and conscientiousness. The bivariate analyses showed that the variance explained by common variants entirely overlapped between neuroticism and openness (rG=1.00, P <0.001), despite low phenotypic correlation (r=−0.09, P <0.001), suggesting that the remaining unique heritability may be determined by rare or structural variants. As far as we are aware of, this is the first study estimating the shared and unique heritability of all Big Five personality traits using the GREML approach. Findings should be considered exploratory and suggest that detectable heritability estimates based on common variants is shared between neuroticism and openness to experiences
Peccei-Quinn extended gauge-mediation model with vector-like matter
We construct a gauge-mediated SUSY breaking model with vector-like matters
combined with the Peccei-Quinn mechanism to solve the strong CP problem. The
Peccei-Quinn symmetry plays an essential role for generating sizable masses for
the vector-like matters and the -term without introducing dangerous CP
angle. The model naturally explains both the 125GeV Higgs mass and the muon
anomalous magnetic moment. The stabilization of the Peccei-Quinn scalar and the
cosmology of the saxion and axino are also discussed.Comment: 33 pages, 5 figures; version to be published (JHEP
Protein C anticoagulant system—anti-inflammatory effects
Activated protein C (APC) plays active roles in preventing progression of a number of disease processes. These include thrombosis due to its direct anticoagulant activity which is likely augmented by its cytoprotective activity, thereby limiting exposure of procoagulant cellular membrane surfaces on cells. Beyond that, the pathway signals the cells to prevent apoptosis, to dampen inflammation, to increase endothelial barrier function, and to selectively downregulate some genes implicated in disease progression. Most of these functions are manifested to APC binding to endothelial protein C receptor (EPCR) allowing PAR1 activation, but activation of other PARS is also implicated in some cases. In addition to EPCR orchestrating these changes, CD11b is also capable of supporting APC signaling. Selective control of these pathways offers potential in new therapeutic approaches to disease
Axino Cold Dark Matter Revisited
Axino arises in supersymmetric versions of axion models and is a natural
candidate for cold or warm dark matter. Here we revisit axino dark matter
produced thermally and non-thermally in light of recent developments. First we
discuss the definition of axino relative to low energy axion one for several
KSVZ and DFSZ models of the axion. Then we review and refine the computation of
the dominant QCD production in order to avoid unphysical cross-sections and,
depending on the model, to include production via SU(2) and U(1) interactions
and Yukawa couplings.Comment: 30 pages, 10 figures, version accepted by JHE
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