794 research outputs found
Nonstandard electroconvection in a bent-core oxadiazole material
Electroconvection (EC) phenomena have been investigated in the nematic phase of a bent-core oxadiazole material with negative dielectric anisotropy and a frequency dependent conductivity anisotropy. The formation of longitudinal roll (LR) patterns is one of the predominant features observed in the complete frequency and voltage range studied. At voltages much above the LR threshold, various complex patterns such as the "crisscrossed" pattern, bimodal varicose, and turbulence are observed. Unusually, the nonstandard EC (ns-EC) instability in this material, is observed in a regime in which we measure the dielectric and conductivity anisotropies to be negative and positive respectively. A further significant observation is that the EC displays distinct features in the high and low temperature regimes of the nematic phase, supporting an earlier report that EC patterns could distinguish between regions that have been reported as uniaxial and biaxial nematic phases
PDB3: USE OF BOOTSTRAP IN A COST-OF-ILLNESS STUDY TO DERIVE ACCURACY OF ESTIMATES
Farrando, Jordi;Febles, Maria Dolors ;Henrich, Jordi;TarrasĂł, Olga ;Fuertes, J.C.;PĂ©rez, S
Effects of maleimide-polyethylene glycol-modified human hemoglobin (MP4) on tissue necrosis in SKH1-hr hairless mice
<p>Abstract</p> <p>Objective</p> <p>Tissue hypoxia after blood loss, replantation and flap reperfusion remains a challenging task in surgery. Normovolemic hemodilution improves hemorheologic properties without increasing oxygen carrying capacity. Red blood cell transfusion is the current standard of treatment with its attendant risks. The aim of this study was to investigate the potential of the chemically modified hemoglobin, MP4, to reduce skin flap necrosis and its effect on selected blood markers and kidneys.</p> <p>Materials and methods</p> <p>Tissue ischemia was induced in the ear of hairless mice (n = 26). Hemodilution was performed by replacing one third of blood volume with the similar amount of MP4, dextran, or blood. The extent of non-perfused tissue was assessed by intravital fluorescent microscopy.</p> <p>Results</p> <p>Of all groups, MP4 showed the smallest area of no perfusion (in percentage of the ear ± SEM: 16.3% ± 2.4), the control group the largest (22.4% ± 3.5). Leukocytes showed a significant increase in the MP4 and dextran group (from 8.7 to 13.6 respectively 15.4*10<sup>9</sup>/l). On histology no changes of the kidneys could be observed.</p> <p>Conclusion</p> <p>MP4 causes an increase of leukocytes, improves the oxygen supply of the tissue and shows no evidence of renal impairment.</p
Electroweak Constraints on Warped Geometry in Five Dimensions and Beyond
Here we consider the tree level corrections to electroweak (EW) observables
from standard model (SM) particles propagating in generic warped extra
dimensions. The scale of these corrections is found to be dominated by three
parameters, the Kaluza-Klein (KK) mass scale, the relative coupling of the KK
gauge fields to the Higgs and the relative coupling of the KK gauge fields to
fermion zero modes. It is found that 5D spaces that resolve the hierarchy
problem through warping typically have large gauge-Higgs coupling. It is also
found in where the additional dimensions are warped the relative
gauge-Higgs coupling scales as a function of the warp factor. If the warp
factor of the additional spaces is contracting towards the IR brane, both the
relative gauge-Higgs coupling and resulting EW corrections will be large.
Conversely EW constraints could be reduced by finding a space where the
additional dimension's warp factor is increasing towards the IR brane. We
demonstrate that the Klebanov Strassler solution belongs to the former of these
possibilities.Comment: 18 pages, 3 figures (references added) version to appear in JHE
Experimental determination of the complete spin structure for anti-proton + proton -> anti-\Lambda + \Lambda at anti-proton beam momentum of 1.637 GeV/c
The reaction anti-proton + proton -> anti-\Lambda + \Lambda -> anti-proton +
\pi^+ + proton + \pi^- has been measured with high statistics at anti-proton
beam momentum of 1.637 GeV/c. The use of a transversely-polarized frozen-spin
target combined with the self-analyzing property of \Lambda/anti-\Lambda decay
allows access to unprecedented information on the spin structure of the
interaction. The most general spin-scattering matrix can be written in terms of
eleven real parameters for each bin of scattering angle, each of these
parameters is determined with reasonable precision. From these results all
conceivable spin-correlations are determined with inherent self-consistency.
Good agreement is found with the few previously existing measurements of spin
observables in anti-proton + proton -> anti-\Lambda + \Lambda near this energy.
Existing theoretical models do not give good predictions for those
spin-observables that had not been previously measured.Comment: To be published in Phys. Rev. C. Tables of results (i.e. Ref. 24) are
available at http://www-meg.phys.cmu.edu/~bquinn/ps185_pub/results.tab 24
pages, 16 figure
Electroweak and Flavour Structure of a Warped Extra Dimension with Custodial Protection
We present the electroweak and flavour structure of a model with a warped
extra dimension and the bulk gauge group SU(3) x SU(2)_L x SU(2)_R x P_LR x
U(1)_X. The presence of SU(2)_R implies an unbroken custodial symmetry in the
Higgs system allowing to eliminate large contributions to the T parameter,
whereas the P_LR symmetry and the enlarged fermion representations provide a
custodial symmetry for flavour diagonal and flavour changing couplings of the
SM Z boson to left-handed down-type quarks. We diagonalise analytically the
mass matrices of charged and neutral gauge bosons including the first KK modes.
We present the mass matrices for quarks including heavy KK modes and discuss
the neutral and charged currents involving light and heavy fields. We give the
corresponding complete set of Feynman rules in the unitary gauge.Comment: 74 pages, 2 figures. clarifying comments and references added,
version to be published in JHE
Measurement of Spin Transfer Observables in Antiproton-Proton -> Antilambda-Lambda at 1.637 GeV/c
Spin transfer observables for the strangeness-production reaction
Antiproton-Proton -> Antilambda-Lambda have been measured by the PS185
collaboration using a transversely-polarized frozen-spin target with an
antiproton beam momentum of 1.637 GeV/c at the Low Energy Antiproton Ring at
CERN. This measurement investigates observables for which current models of the
reaction near threshold make significantly differing predictions. Those models
are in good agreement with existing measurements performed with unpolarized
particles in the initial state. Theoretical attention has focused on the fact
that these models produce conflicting predictions for the spin-transfer
observables D_{nn} and K_{nn}, which are measurable only with polarized target
or beam. Results presented here for D_{nn} and K_{nn} are found to be in
disagreement with predictions from existing models. These results also
underscore the importance of singlet-state production at backward angles, while
current models predict complete or near-complete triplet-state dominance.Comment: 5 pages, 3 figure
Les Houches 2015: Physics at TeV colliders - new physics working group report
We present the activities of the 'New Physics' working group for the 'Physics
at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report
includes new physics studies connected with the Higgs boson and its properties,
direct search strategies, reinterpretation of the LHC results in the building
of viable models and new computational tool developments. Important signatures
for searches for natural new physics at the LHC and new assessments of the
interplay between direct dark matter searches and the LHC are also considered.Comment: Proceedings of the New Physics Working Group of the 2015 Les Houches
Workshop, Physics at TeV Colliders, Les Houches 1-19 June 2015. 197 page
Reducing Constraints in a Higher Dimensional Extension of the Randall and Sundrum Model
In order to investigate the phenomenological implications of warped spaces in
more than five dimensions, we consider a dimensional extension to
the Randall and Sundrum model in which the space is warped with respect to a
single direction by the presence of an anisotropic bulk cosmological constant.
The Einstein equations are solved, giving rise to a range of possible spaces in
which the additional spaces are warped. Here we consider models in
which the gauge fields are free to propagate into such spaces. After carrying
out the Kaluza Klein (KK) decomposition of such fields it is found that the KK
mass spectrum changes significantly depending on how the additional
dimensions are warped. We proceed to compute the lower bound on the KK mass
scale from electroweak observables for models with a bulk
gauge symmetry and models with a bulk gauge
symmetry. It is found that in both cases the most favourable bounds are
approximately TeV, corresponding to a mass of the first gauge
boson excitation of about 4-6 TeV. Hence additional warped dimensions offer a
new way of reducing the constraints on the KK scale.Comment: 27 pages, 15 figures, v3: Additional comments in sections 1, 2 and 4.
New appendix added. Five additional figures. References adde
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