3,835 research outputs found
Killing spinors in supergravity with 4-fluxes
We study the spinorial Killing equation of supergravity involving a torsion
3-form \T as well as a flux 4-form \F. In dimension seven, we construct
explicit families of compact solutions out of 3-Sasakian geometries, nearly
parallel \G_2-geometries and on the homogeneous Aloff-Wallach space. The
constraint \F \cdot \Psi = 0 defines a non empty subfamily of solutions. We
investigate the constraint \T \cdot \Psi = 0, too, and show that it singles
out a very special choice of numerical parameters in the Killing equation,
which can also be justified geometrically
Importance of atropine challenge test in the current era of electrophysiology
Mobitz II block is misunderstood more than any other abnormality of rhythm or conduction”. The concept of 2:1 AV block remains poorly understood by many physicians even after so many years of advancement in the field of electrophysiology. It cannot be classified into type I or type II second-degree AV block because there is only one PR interval to examine before the blocked P waveA 46 year male admitted with chief complaints of effort intolerance and non anginal chest pain of fifteen days duration. His resting ECG revealed 2:1 conduction of P wave, before and after non conducted P wave PR interval was constant and of normal duration. So in order to define the site of block we performed the atropine challenge test as the patient was not able to walk. On administration of atropine ECG revealed worsening of AV block in a 3:1 to 4:1 conduction of P wave with narrow complex QRS. This finding suggesting the block is in bundle of his or branches. This patient underwent Electrophysiological study. Electro physiological tracings showed normal PR interval, QRS duration, with 2:1 AV block. The non conducted P wave was blocked at the level of distal His bundle.This case illustrated the importance of localisation of site of block in 2:1 AV block in order to manage the case appropriately. Both vagal manoeuvres and exercise can help in localising the site of block, which will be confirmed by electrophysiology study.
Exclusive radiative and electroweak b->d and b->s penguin decays at NLO
We provide Standard Model expectations for the rare radiative decays B->K^*
gamma, B->rho gamma and B-> omega gamma, and the electroweak penguin decays
B->K^* l^+ l^- and B->rho l^+ l^- at the next-to-leading order (NLO), extending
our previous results to b->d transitions. We consider branching fractions,
isospin asymmetries and direct CP asymmetries. For the electroweak penguin
decays, the lepton-invariant mass spectrum and forward-backward asymmetry is
also included. Radiative and electroweak penguin transitions in b->d are mainly
interesting in the search for new flavour-changing neutral current
interactions, but in addition the B->rho gamma decays provide constraints on
the CKM parameters (\bar\rho,\bar\eta). The potential impact of these
constraints is discussed.Comment: 29 pages, LaTe
Symmetry-breaking corrections to heavy-to-light B meson form factors at large recoil
Recently it has been shown that symmetries emerging in the heavy quark and
large recoil energy limit impose various relations on form factors that
parametrise the decay of B mesons into light mesons. These symmetries are
broken by perturbative effects. In this paper we discuss the structure of
heavy-to-light form factors including such effects and compute
symmetry-breaking corrections to first order in the strong coupling. As an
application of our results we consider the forward-backward asymmetry zero in
the rare decay B -> V l^+ l^- and the possibility to constrain potential new
physics contributions to the Wilson coefficient C_9.Comment: 30 pages, LaTeX (typos in eq. (44), (46) corrected
Miocene Shark and Batoid Fauna from Nosy Makamby (Mahajanga Basin, Northwestern Madagascar)
published_or_final_versio
Finding the discriminative frequencies of motor electroencephalography signal using genetic algorithm
A crucial part of the brain-computer interface is a classification of electroencephalography (EEG) motor tasks. Artifacts such as eye and muscle movements corrupt EEG signal and reduce the classification performance. Many studies try to extract not redundant and discriminative features from EEG signals. Therefore, this study proposed a signal preprocessing and feature extraction method for EEG classification. It consists of removing the artifacts by using discrete fourier transform (DFT) as an ideal filter for specific frequencies. It also cross-correlates the EEG channels with the effective channels to emphases the EEG motor signals. Then the resultant from cross correlation are statistical calculated to extract feature for classifying a left and right finger movements using support vector machine (SVM). The genetic algorithm was applied to find the discriminative frequencies of DFT for the two EEG classes signal. The performance of the proposed method was determined by finger movement classification of 13 subjects and the experiments show that the average accuracy is above 93 percent
Fabrication of Lateral Polysilicon Gap of Less than 50nm Using Conventional Lithography
We report a thermal oxidation process for the fabrication of nanogaps of less than 50 nmin dimension.Nanogaps of this dimension
are necessary to eliminate contributions from double-layer capacitance in the dielectric detection of protein or nucleic acid. The
method combines conventional photolithography and pattern-size reduction techniques. The gaps are fabricated on polysiliconcoated
silicon substrate with gold electrodes. The dimensions of the structure are determined by scanning electron microscopy
(SEM). An electrical characterization of the structures by dielectric analyzer (DA) shows an improved conductivity as well
as enhanced permittivity and capacity with the reduction of gap size, suggesting its potential applications in the detection of
biomolecule with very low level of power supply. Two chrome Masks are used to complete the work: the first Mask is for the
nanogap pattern and the second one is for the electrodes. An improved resolution of pattern size is obtained by controlling the
oxidation time. The method expected to enable fabrication of nanogaps with a wide ranging designs and dimensions on different
substrates. It is a simple and cost-effective method and does not require complicated nanolithography process for fabricating
desired nanogaps in a reproducible fashion
EFFECT OF HARMONICS ON A SOLID-ROTOR INDUCTION MOTOR
The paper records a study of an investigating the performance of a solid-rotor induction motor with
a rectilinear inverter excitation to identify the effects of the associated time harmonics. The
performance is determined experimentally by using a stator of a three-phase laboratory induction
motor that is fitted with a solid-steel rotor and compared with the theoretical model developed
which uses the Fourier components of the supply voltage waveform. Final conclusions are drawn
from comparing motor performances with sinusoidal and inverter excitations. An equivalent circuit
model is developed to determine the harmonic currents. The development of the theoretical model
make use of the results of existing field analyses. Harmonic currents and other performance details
including the possible interactions between the co-existing harmonics are determined and discussed.
The measured values of torque, input current and power over full speed range with the two types of
excitation are presented, and compared with the theoretical values. The waveforms of current, phase
and line voltages are analyzed experimentally and compared with simulation results. The theoretical
results correlate well with measured results and the significant harmonic effects are identifie
Unquenched QCD with Light Quarks
We present recent results in unquenched lattice QCD with two degenerate light
sea quarks using the truncated determinant approximation (TDA). In the TDA the
infrared modes contributing to the quark determinant are computed exactly up to
some cutoff in quark off-shellness (typically 2). This approach
allows simulations to be performed at much lighter quark masses than possible
with conventional hybrid MonteCarlo techniques. Results for the static energy
and topological charge distributions are presented using a large ensemble
generated on very coarse (6) but physically large lattices. Preliminary
results are also reported for the static energy and meson spectrum on 10x20
lattices (lattice scale =1.15 GeV) at quark masses corresponding to
pions of mass 200 MeV. Using multiboson simulation to compute the
ultraviolet part of the quark determinant the TDA approach becomes an exact
with essentially no increase in computational effort. Some preliminary results
using this fully unquenched algorithm are presented.Comment: LateX, 39 pages, 16 eps figures, 1 ps figur
Exclusive Radiative B-Decays in the Light-Cone QCD Sum Rule Approach
We carry out a detailed study of exclusive radiative rare -decays in the
framework of the QCD sum rules on the light cone, which combines the
traditional QCD sum rule technique with the description of final state vector
mesons in terms of the light-cone wave functions of increasing twist. The
decays considered are: and the corresponding decays of the mesons, and . Based on our estimate of the transition
form factor F_1^{B \to K^*\pg}(0) =0.32\pm0.05, we find for the branching
ratio , which is in
agreement with the observed value measured by the CLEO collaboration. We
present detailed estimates for the ratios of the radiative decay form factors,
which are then used to predict the rates for the exclusive radiative B-decays
listed above. This in principle allows the extraction of the CKM matrix element
from the penguin-dominated CKM-suppressed radiative decays when they
are measured. We give a detailed discussion of the dependence of the form
factors on the -quark mass and on the momentum transfer, as well as their
interrelation with the CKM-suppressed semileptonic decay form factors in , which we also calculate in our approach.Comment: 32 pages, 10 uuencoded figures, LaTeX, preprint CERN-TH 7118/9
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