15,447 research outputs found
Production of Z' and W' via Drell-Yan processes in the 4D Composite Higgs Model at the LHC
We present an analysis of both the Neutral Current (NC) and Charged Current
(CC) Drell-Yan processes at the LHC within a 4 Dimensional realization of a
Composite Higgs model studying the cross sections and taking into account the
possible impact of the extra fermions present in the spectrum.Comment: Conference proceeding, XII IFAE Edition, 3-5 April 2013, Cagliari. 2
pages, 2 figures; v2 typo correcte
Higgs Boson in the 4DCHM: LHC phenomenology
Composite Higgs models provide an elegant solution to the hierarchy problem
present in the Standard Model (SM) and give an alternative pattern leading to
the mechanism of Electro-Weak Symmetry Breaking (EWSB). We present an analysis
of the Higgs boson production and decay within a recently proposed realistic
realization of this general idea: the 4D Composite Higgs Model (4DCHM).
Comparing our results with the latest Large Hadron Collider (LHC) data we show
that the 4DCHM could provide an alternative explanation with respect to the SM
of the LHC results pointing to the discovery of a Higgs-like particle at 125
GeV.Comment: Conference proceeding, EPS-HEP 2013, 18-24 July 2013, Stockholm. 3
pages, 2 figures, typo correcte
Quantifying selection in immune receptor repertoires
The efficient recognition of pathogens by the adaptive immune system relies
on the diversity of receptors displayed at the surface of immune cells. T-cell
receptor diversity results from an initial random DNA editing process, called
VDJ recombination, followed by functional selection of cells according to the
interaction of their surface receptors with self and foreign antigenic
peptides. To quantify the effect of selection on the highly variable elements
of the receptor, we apply a probabilistic maximum likelihood approach to the
analysis of high-throughput sequence data from the -chain of human
T-cell receptors. We quantify selection factors for V and J gene choice, and
for the length and amino-acid composition of the variable region. Our approach
is necessary to disentangle the effects of selection from biases inherent in
the recombination process. Inferred selection factors differ little between
donors, or between naive and memory repertoires. The number of sequences shared
between donors is well-predicted by the model, indicating a purely stochastic
origin of such "public" sequences. We find a significant correlation between
biases induced by VDJ recombination and our inferred selection factors,
together with a reduction of diversity during selection. Both effects suggest
that natural selection acting on the recombination process has anticipated the
selection pressures experienced during somatic evolution
Predicting the spectrum of TCR repertoire sharing with a data-driven model of recombination
Despite the extreme diversity of T cell repertoires, many identical T-cell
receptor (TCR) sequences are found in a large number of individual mice and
humans. These widely-shared sequences, often referred to as `public', have been
suggested to be over-represented due to their potential immune functionality or
their ease of generation by V(D)J recombination. Here we show that even for
large cohorts the observed degree of sharing of TCR sequences between
individuals is well predicted by a model accounting for by the known
quantitative statistical biases in the generation process, together with a
simple model of thymic selection. Whether a sequence is shared by many
individuals is predicted to depend on the number of queried individuals and the
sampling depth, as well as on the sequence itself, in agreement with the data.
We introduce the degree of publicness conditional on the queried cohort size
and the size of the sampled repertoires. Based on these observations we propose
a public/private sequence classifier, `PUBLIC' (Public Universal Binary
Likelihood Inference Classifier), based on the generation probability, which
performs very well even for small cohort sizes
Compression of Atomic Phase Space Using an Asymmetric One-Way Barrier
We show how to construct asymmetric optical barriers for atoms. These
barriers can be used to compress phase space of a sample by creating a confined
region in space where atoms can accumulate with heating at the single photon
recoil level. We illustrate our method with a simple two-level model and then
show how it can be applied to more realistic multi-level atoms
Renal cyst epithelial transport in non-uremic polycystic kidney disease
Renal cyst epithelial transport in non-uremic polycystic kidney disease. Renal cyst epithelial transport of organic molecules was investigated during three separate cyst drainage procedures in a non-uremic patient with polycystic kidney disease (PCKD). Following constant intravenous inulin infusion, four of eight sampled cysts achieved concentrations exceeding those expected by glomerular filtration alone. Likewise, cyst concentrations of the filtered radionuclide Tc DTP A were up to 3.7 times simultaneous plasma levels. Both PAH and I-131 hippuran accumulated in all cysts suggesting intact tubular secretory mechanisms. Quantitative amino acid levels in two proximal nephron cysts were identical to serum. Since concentrations of inulin, DTPA, and amino acids exceed levels expected if cystic nephrons had normal glomerular filtration and tubular reabsorptive properties, other mechanisms are likely. Simple diffusion across altered epithelial surfaces could partially account for the observed cyst concentrations of each organic molecule and, by ion trapping, contribute to progressive cyst growth in PCKD.Transport épithélial kystique rénal dans la maladie polykystique rénale non-urémique. Le transport épithélial kystique rénal de molécules organiques a été étudié pendant trois drainages kystiques séparés chez un malade non urémique atteint de maladie polykystique (PCKD). Après une perfusion constante intraveineuse d'inuline, les recueils de quartre sur huit kystes indiquaient des concentrations dépassant celles attendues par la seule filtration glomérulaire. De même, les concentrations kystiques du radionuclide Tc DTPA filtré atteignaient jusqu'à 3,7 fois les valeurs plasmatiques au même moment. Le PAH et le I-131 hippuran s'accumulaient dans tous les kystes, suggérant des mécanismes sécrétoires tubulaires intacts. Les niveaux quantitatifs d'aminoacides dans deux kystes néphroniques proximaux étaient identiques au sérum. Puisque les concentrations d'inuline, de DTPA et d'aminoacides dépassent les niveaux attendus si les néphrons kystiques avaient une filtration glomérulaire normale et des propriétés de réabsorption tubulaire, d'autres mécanismes sont probables. La simple diffusion à travers des surfaces épithéliales altérées pourrait partiellement rendre compte des concentrations kystiques observées pour chaque molécule organique, et, par capture ionique, contribuer à la croissance progressive des kystes dans la PCKD
Legislative Control of the Menhaden Fishery
This year, six menhaden- related bills were introduced in the Virginia General Assembly. Delegate John Cosgrove (RChesapeake) introduced legislation in the House of Delegates that was identical to Senate Bill 765, a bill that proposed to shift oversight of the menhaden fishery to the VMRC. This article aims to highlight the unique stance taken by Virginia\u27s legislature and explain why this management is better left to the commission responsible for managing every other fishery in the Commonwealth. While there may not be a conclusive link between reduction industry practices and a decline in water quality, Virginia\u27s legislators should recognize the shift towards an ecosystem-based model as the most effective way to sustainably manage fisheries and all natural resources
Legislative Control of the Menhaden Fishery
This year, six menhaden- related bills were introduced in the Virginia General Assembly. Delegate John Cosgrove (RChesapeake) introduced legislation in the House of Delegates that was identical to Senate Bill 765, a bill that proposed to shift oversight of the menhaden fishery to the VMRC. This article aims to highlight the unique stance taken by Virginia\u27s legislature and explain why this management is better left to the commission responsible for managing every other fishery in the Commonwealth. While there may not be a conclusive link between reduction industry practices and a decline in water quality, Virginia\u27s legislators should recognize the shift towards an ecosystem-based model as the most effective way to sustainably manage fisheries and all natural resources
Experimental recovery of a qubit from partial collapse
We describe and implement a method to restore the state of a single qubit, in
principle perfectly, after it has partially collapsed. The method resembles the
classical Hahn spin-echo, but works on a wider class of relaxation processes,
in which the quantum state partially leaves the computational Hilbert space. It
is not guaranteed to work every time, but successful outcomes are heralded. We
demonstrate using a single trapped ion better performance from this recovery
method than can be obtained employing projection and post-selection alone. The
demonstration features a novel qubit implementation that permits both partial
collapse and coherent manipulations with high fidelity.Comment: 5 pages, 3 figure
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