434 research outputs found
On the Stereochemistry of the Cations in the Doping Block of Superconducting Copper-Oxides
Metal-oxygen complexes containing Cu,- Tl-, Hg-, Bi- and Pb-cations are
electronically active in superconducting copper-oxides by stabilizing single
phases with enhanced , whereas other metal-oxygen complexes deteriorate
copper-oxide superconductivity. Cu, Tl, Hg, Bi, Pb in their actual oxidation
states are closed shell or inert pair ions. Their electronic
configurations have a strong tendency to polarize the oxygen environment. The
closed shell ions with low lying
excitations form linear complexes through hybridization polarizing
the apical oxygens. Comparatively low excitation energies
distinguish from other closed shell
ions deteriorating copper-oxide superconductivity, {\it e.g.} .Comment: 5 pages, uses REVTEX. To be published in: J. Superconductivity, Proc.
Int. Workshop on "Phase Separation, Electronic Inhomogenities and Related
Mechanisms for High T_c Superconductors", Erice (Sicily) 9-15 July 199
Two-parameter neutrino mass matrices with two texture zeros
We reanalyse Majorana-neutrino mass matrices M_nu with two texture zeros, by
searching for viable hybrid textures in which the non-zero matrix elements of
M_nu have simple ratios. Referring to the classification scheme of Frampton,
Glashow and Marfatia, we find that the mass matrix denoted by A1 allows the
ratios (M_nu)_{mu mu} : (Mnu)_{tau tau} = 1:1 and (M_nu)_{e tau} : (Mnu)_{mu
tau} = 1:2. There are analogous ratios for texture A2. With these two hybrid
textures, one obtains, for instance, good agreement with the data if one
computes the three mixing angles in terms of the experimentally determined
mass-squared differences Delta m^2_21 and Delta m^2_31. We could not find
viable hybrid textures based on mass matrices different from those of cases A1
and A2.Comment: 10 pages, no figures, minor changes, some references adde
Identification of {HNRNPK} as Regulator of Hepatitis {C} Virus Particle Production
Hepatitis C virus (HCV) is a major cause of chronic liver disease affecting around 130 million people worldwide. While great progress has been made to define the principle steps of the viral life cycle, detailed knowledge how HCV interacts with its host cells is still limited. To overcome this limitation we conducted a comprehensive whole-virus RNA interference-based screen and identified 40 host dependency and 16 host restriction factors involved in HCV entry/replication or assembly/release. Of these factors, heterogeneous nuclear ribonucleoprotein K (HNRNPK) was found to suppress HCV particle production without affecting viral RNA replication. This suppression of virus production was specific to HCV, independent from assembly competence and genotype, and not found with the related Dengue virus. By using a knock-down rescue approach we identified the domains within HNRNPK required for suppression of HCV particle production. Importantly, HNRNPK was found to interact specifically with HCV RNA and this interaction was impaired by mutations that also reduced the ability to suppress HCV particle production. Finally, we found that in HCV-infected cells, subcellular distribution of HNRNPK was altered; the protein was recruited to sites in close proximity of lipid droplets and colocalized with core protein as well as HCV plus-strand RNA, which was not the case with HNRNPK variants unable to suppress HCV virion formation. These results suggest that HNRNPK might determine efficiency of HCV particle production by limiting the availability of viral RNA for incorporation into virions. This study adds a new function to HNRNPK that acts as central hub in the replication cycle of multiple other viruses
Proceedings of the 2nd Workshop on Flavor Symmetries and Consequences in Accelerators and Cosmology (FLASY12)
These are the proceedings of the 2nd Workshop on Flavor Symmetries and
Consequences in Accelerators and Cosmology, held 30 June 2012 - 4 July 2012,
Dortmund, Germany.Comment: Order 400 pages, several figures including the group picture v2:
corrected author list and contributio
A comparative study on the felting propensity of animal fibers
The felting propensity of different animal fibers, particularly alpaca and wool, has been examined. The Aachen felting test method was employed. 1 g of each type of fiber was soaked in 50 ml of wetting solution and agitated in a dyeing machine to make felt balls. The diameter of each ball was measured in nine directions and the ball density was calculated in g/cm3; the higher the density value of the ball, the higher the feltability of the fibers. The effects of fiber diameter and fiber length on the felting propensity of these fibers were investigated. The results show that the alpaca fibers felt to a higher degree than wool fibers, and short and fine cashmere fibers have lower felting propensity than wool fibers at a similar diameter range. There is a higher tendency of felting for bleached and dyed alpaca fibers than for untreated fibers. Fiber length has a remarkable influence on the propensity of fiber felting. Cotton and nylon fibers were also tested for felting propensity to verify the mechanism responsible for the different fiber felting behavior. <br /
Flavor Violating Higgs Decays
We study a class of nonstandard interactions of the newly discovered 125 GeV
Higgs-like resonance that are especially interesting probes of new physics:
flavor violating Higgs couplings to leptons and quarks. These interaction can
arise in many frameworks of new physics at the electroweak scale such as two
Higgs doublet models, extra dimensions, or models of compositeness. We rederive
constraints on flavor violating Higgs couplings using data on rare decays,
electric and magnetic dipole moments, and meson oscillations. We confirm that
flavor violating Higgs boson decays to leptons can be sizeable with, e.g., h ->
tau mu and h -> tau e branching ratios of order 10% perfectly allowed by low
energy constraints. We estimate the current LHC limits on h -> tau mu and h ->
tau e decays by recasting existing searches for the SM Higgs in the tau-tau
channel and find that these bounds are already stronger than those from rare
tau decays. We also show that these limits can be improved significantly with
dedicated searches and we outline a possible search strategy. Flavor violating
Higgs decays therefore present an opportunity for discovery of new physics
which in some cases may be easier to access experimentally than flavor
conserving deviations from the Standard Model Higgs framework.Comment: 39 pages, 12 figures, 3 tables; v2: Improved referencing, updated mu
-> 3e bounds to include large loop contributions, corrected single top
constraints; conclusions unchanged; matches version to be published in JHEP;
v3: included 2-loop contributions in mu -> e conversion, improved discussion
of tau -> 3 mu and of EDM constraints on FV top-Higgs couplings; conclusions
unchange
DASMIweb: online integration, analysis and assessment of distributed protein interaction data
In recent years, we have witnessed a substantial increase of the amount of available protein interaction data. However, most data are currently not readily accessible to the biologist at a single site, but scattered over multiple online repositories. Therefore, we have developed the DASMIweb server that affords the integration, analysis and qualitative assessment of distributed sources of interaction data in a dynamic fashion. Since DASMIweb allows for querying many different resources of protein and domain interactions simultaneously, it serves as an important starting point for interactome studies and assists the user in finding publicly accessible interaction data with minimal effort. The pool of queried resources is fully configurable and supports the inclusion of own interaction data or confidence scores. In particular, DASMIweb integrates confidence measures like functional similarity scores to assess individual interactions. The retrieved results can be exported in different file formats like MITAB or SIF. DASMIweb is freely available at http://www.dasmiweb.de
Selective Molecular Sieving through Porous Graphene
Membranes act as selective barriers and play an important role in processes
such as cellular compartmentalization and industrial-scale chemical and gas
purification. The ideal membrane should be as thin as possible to maximize
flux, mechanically robust to prevent fracture, and have well-defined pore sizes
to increase selectivity. Graphene is an excellent starting point for developing
size selective membranes because of its atomic thickness, high mechanical
strength, relative inertness, and impermeability to all standard gases.
However, pores that can exclude larger molecules, but allow smaller molecules
to pass through have to be introduced into the material. Here we show
UV-induced oxidative etching can create pores in micrometre-sized graphene
membranes and the resulting membranes used as molecular sieves. A pressurized
blister test and mechanical resonance is used to measure the transport of a
variety of gases (H2, CO2, Ar, N2, CH4, and SF6) through the pores. The
experimentally measured leak rates, separation factors, and Raman spectrum
agree well with models based on effusion through a small number of
angstrom-sized pores.Comment: to appear in Nature Nanotechnolog
The arrhythmogenic cardiomyopathy-specific coding and non-coding transcriptome in human cardiac stromal cells
Arrhythmogenic cardiomyopathy (ACM) is a genetic autosomal disease characterized by abnormal cell-cell adhesion, cardiomyocyte death, progressive fibro-adipose replacement of the myocardium, arrhythmias and sudden death. Several different cell types contribute to the pathogenesis of ACM, including, as recently described, cardiac stromal cells (CStCs). In the present study, we aim to identify ACM-specific expression profiles of human CStCs derived from endomyocardial biopsies of ACM patients and healthy individuals employing TaqMan Low Density Arrays for miRNA expression profiling, and high throughput sequencing for gene expression quantification
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