818 research outputs found
Charged Higgs bosons in the Next-to MSSM (NMSSM)
The charged Higgs boson decays and
are studied in the framework of the next-to Minimal Supersymmetric Standard
Model (NMSSM). It is found that the decay rate for can
exceed the rates for the and channels both below and above
the top-bottom threshold. The dominance of is most readily
achieved when has a large doublet component and small mass. We also study
the production process at the LHC followed by the decay
which leads to the signature . We suggest
that is a promising discovery channel for a light charged
Higgs boson in the NMSSM with small or moderate and dominant decay
mode . This signature can also arise from
the Higgsstrahlung process followed by the decay . It is shown that there exist regions of parameter space where these
processes can have comparable cross sections and we suggest that their
respective signals can be distinguished at the LHC by using appropriate
reconstruction methods.Comment: 20 pages, 22 eps figures, more reference adde
A new method for determining the sensitivity of X-ray imaging observations and the X-ray number counts
We present a new method for determining the sensitivity of X-ray imaging
observations, which correctly accounts for the observational biases that affect
the probability of detecting a source of a given X-ray flux, without the need
to perform a large number of time consuming simulations. We use this new
technique to estimate the X-ray source counts in different spectral bands
(0.5-2, 0.5-10, 2-10 and 5-10keV) by combining deep pencil-beam and shallow
wide-area Chandra observations. The sample has a total of 6295 unique sources
over an area of and is the largest used to date to determine
the X-ray number counts. We determine, for the first time, the break flux in
the 5-10 keV band, in the case of a double power-law source count distribution.
We also find an upturn in the 0.5-2keV counts at fluxes below about
6e-17erg/s/cm2. We show that this can be explained by the emergence of normal
star-forming galaxies which dominate the X-ray population at faint fluxes. The
fraction of the diffuse X-ray background resolved into point sources at
different spectral bands is also estimated. It is argued that a single
population of Compton thick AGN cannot be responsible for the entire unresolved
X-ray background in the energy range 2-10keV.Comment: Accepted for publication in MNRAS. Data products available at
http://astro.imperial.ac.uk/research/xray
RIXS observation of bond-directional nearest-neighbor excitations in the Kitaev material NaIrO
Spin-orbit coupling locks spin direction and spatial orientation and
generates, in semi-classical magnets, a local spin easy-axis and associated
ordering. Quantum spin-1/2's defy this fate: rather than spins becoming locally
anisotropic, the spin-spin interactions do. Consequently interactions become
dependent on the spatial orientation of bonds between spins, prime theoretical
examples of which are Kitaev magnets. Bond-directional interactions imply the
existence of bond-directional magnetic modes, predicted spin excitations that
render crystallographically equivalent bonds magnetically inequivalent, which
yet have remained elusive experimentally. Here we show that resonant inelastic
x-ray scattering allows us to explicitly probe the bond-directional character
of magnetic excitations. To do so, we use a scattering plane spanned by one
bond and the corresponding spin component and scan a range of momentum transfer
that encompasses multiple Brillouin zones. Applying this approach to
NaIrO we establish the different bond-directional characters of
magnetic excitations at 10 meV and 45 meV. Combined with the observation of
spin-spin correlations that are confined to a single bond, this experimentally
validates the Kitaev character of exchange interactions long proposed for this
material.Comment: 6 pages, 5 figures, plus 4 pages Supplementary Information (incl. 5
figures
Environmental toxicity, redox signaling and lung inflammation:the role of glutathione
Glutathione (γ-glutamyl-cysteinyl-glycine, GSH) is the most abundant intracellular antioxidant thiol and is central to redox defense during oxidative stress. GSH metabolism is tightly regulated and has been implicated in redox signaling and also in protection against environmental oxidant-mediated injury. Changes in the ratio of the reduced and disulfide form (GSH/GSSG) can affect signaling pathways that participate in a broad array of physiological responses from cell proliferation, autophagy and apoptosis to gene expression that involve H(2)O(2) as a second messenger. Oxidative stress due to oxidant/antioxidant imbalance and also due to environmental oxidants is an important component during inflammation and respiratory diseases such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, acute respiratory distress syndrome, and asthma. It is known to activate multiple stress kinase pathways and redox sensitive transcription factors such as Nrf2, NF-κB and AP-1, which differentially regulate the genes for pro-inflammatory cytokines as well as the protective antioxidant genes. Understanding the regulatory mechanisms for the induction of antioxidants, such as GSH, versus pro-inflammatory mediators at sites of oxidant-directed injuries may allow for the development of novel therapies which will allow pharmacological manipulation GSH synthesis during inflammation and oxidative injury. This article features the current knowledge about the role of GSH in redox signaling, GSH biosynthesis and particularly the regulation of transcription factor Nrf2 by GSH and downstream signaling during oxidative stress and inflammation in various pulmonary diseases. We also discussed the current therapeutic clinical trials using GSH and other thiol compounds, such as N-acetyl-L-cysteine, fudosteine, carbocysteine, erdosteine in environment-induced airways disease
Tunnelling Methods and Hawking's radiation: achievements and prospects
The aim of this work is to review the tunnelling method as an alternative
description of the quantum radiation from black holes and cosmological
horizons. The method is first formulated and discussed for the case of
stationary black holes, then a foundation is provided in terms of analytic
continuation throughout complex space-time. The two principal implementations
of the tunnelling approach, which are the null geodesic method and the
Hamilton-Jacobi method, are shown to be equivalent in the stationary case. The
Hamilton-Jacobi method is then extended to cover spherically symmetric
dynamical black holes, cosmological horizons and naked singularities. Prospects
and achievements are discussed in the conclusions.Comment: Topical Review commissioned and accepted for publication by
"Classical and Quantum Gravity". 101 pages; 6 figure
Folate catabolites in spot urine as non-invasive biomarkers of folate status during habitual intake and folic acid supplementation.
Folate status, as reflected by red blood cell (RCF) and plasma folates (PF), is related to health and disease risk. Folate degradation products para-aminobenzoylglutamate (pABG) and para-acetamidobenzoylglutamate (apABG) in 24 hour urine have recently been shown to correlate with blood folate.
Since blood sampling and collection of 24 hour urine are cumbersome, we investigated whether the determination of urinary folate catabolites in fasted spot urine is a suitable non-invasive biomarker for folate status in subjects before and during folic acid supplementation.
Immediate effects of oral folic acid bolus intake on urinary folate catabolites were assessed in a short-term pre-study. In the main study we included 53 healthy men. Of these, 29 were selected for a 12 week folic acid supplementation (400 µg). Blood, 24 hour and spot urine were collected at baseline and after 6 and 12 weeks and PF, RCF, urinary apABG and pABG were determined.
Intake of a 400 µg folic acid bolus resulted in immediate increase of urinary catabolites. In the main study pABG and apABG concentrations in spot urine correlated well with their excretion in 24 hour urine. In healthy men consuming habitual diet, pABG showed closer correlation with PF (rs = 0.676) and RCF (rs = 0.649) than apABG (rs = 0.264, ns and 0.543). Supplementation led to significantly increased folate in plasma and red cells as well as elevated urinary folate catabolites, while only pABG correlated significantly with PF (rs = 0.574) after 12 weeks.
Quantification of folate catabolites in fasted spot urine seems suitable as a non-invasive alternative to blood or 24 hour urine analysis for evaluation of folate status in populations consuming habitual diet. In non-steady-state conditions (folic acid supplementation) correlations between folate marker (RCF, PF, urinary catabolites) decrease due to differing kinetics
Nuclear Reprogramming Strategy Modulates Differentiation Potential of Induced Pluripotent Stem Cells
Bioengineered by ectopic expression of stemness factors, induced pluripotent stem (iPS) cells demonstrate embryonic stem cell-like properties and offer a unique platform for derivation of autologous pluripotent cells from somatic tissue sources. In the process of nuclear reprogramming, somatic tissues are converted to a pluripotent ground state, thus unlocking an unlimited potential to expand progenitor pools. Molecular dissection of nuclear reprogramming suggests that a residual memory derived from the original parental source, along with the remnants of the reprogramming process itself, leads to a biased potential of the bioengineered progeny to differentiate into target tissues such as cardiac cytotypes. In this way, iPS cells that fulfill pluripotency criteria may display heterogeneous profiles for lineage specification. Small molecule-based strategies have been identified that modulate the epigenetic state of reprogrammed cells and are optimized to erase the residual memory and homogenize the differentiation potential of iPS cells derived from distinct backgrounds. Here, we describe the salient components of the reprogramming process and their effect on the downstream differentiation capacity of the iPS populations in the context of cardiovascular regenerative applications
Electroweak Symmetry Breaking at the LHC
One of the major goals of the Large Hadron Collider is to probe the
electroweak symmetry breaking mechanism and the generation of the masses of the
elementary particles. We review the physics of the Higgs sector in the Standard
Model and some of its extensions such as supersymmetric theories and models of
extra dimensions. The prospects for discovering the Higgs particles at the LHC
and the study of their fundamental properties are summarised.Comment: 27 pages, 45 figures, uses LaTeX (insa.sty). Invited review for
volume on LHC physics to celebrate the Platinum Jubilee of the Indian
National Science Academy, edited by Amitava Datta, Biswarup Mukhopadhyaya and
Amitava Raychaudhuri. Expanded the acronym in the title in the annoncement.
No other change in the text or reference
Extensive Copy-Number Variation of Young Genes across Stickleback Populations
MM received funding from the Max Planck innovation funds for this project. PGDF was supported by a Marie Curie European Reintegration Grant (proposal nr 270891). CE was supported by German Science Foundation grants (DFG, EI 841/4-1 and EI 841/6-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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