3,498 research outputs found
Probing the superconducting gap symmetry of PrRuSb: A comparison with PrOsSb
We report measurements of the magnetic penetration depth in single
crystals of PrRuSb down to 0.1 K. Both and superfluid
density exhibit an exponential behavior for 0.5, with
parameters (0)/\textit{k}\textit{T} = 1.9 and
= 2900 \AA. The value of (0) is consistent with the specific-heat jump
value of = 1.87 measured elsewhere, while the value of
is consistent with the measured value of the electronic
heat-capacity coefficient . Our data are consistent with
PrRuSb being a moderate-coupling, fully-gapped superconductor. We
suggest experiments to study how the nature of the superconducting state
evolves with increasing Ru substitution for Os
Probing Lepton Flavor Violation at Future Colliders
Supersymmetric theories with significant lepton flavor violation have
and nearly degenerate. In this case, pair production
of and at LEPII and at
the Next Linear Collider leads to the phenomenon of slepton oscillations, which
is analogous to neutrino oscillations. The reach in and gives a probe of lepton flavor violation which is significantly more
powerful than the current bounds from rare processes, such as . Polarizable beams and the mode at the NLC are found to
be promising options.Comment: 10 pages, 3 figures, RevTeX, minor corrections, published versio
Modelling growth of swietenia macrophylla (mahogany) plantation in Gum-Gum Forest Reserve, Sabah.
Growth models can contribute to the forest management decision making process by providing stand development forecasts. Mahogany plantation in Gum-Gum Forest Reserve Sabah was planted in 1968 with spacing 2.74×2.74 m within an area of 0.52 hectare. Diameter at breast height (dbh) and tree height data were collected from year 1969 to 2006. This study aimed to determine the efficient regression equations for growth prediction of the mahogany plantation. Regression models were developed by search from literature as a basis references. Four diameter prediction models and six height prediction models were developed. Proc Reg in SAS was used to evaluate the regression equations. Performance of the model was measured by using root mean square error (RMSE), bias and coefficient of determination (R2). The chosen diameter prediction model is lnH=3.07-10.42D-1+0.1lnA with RMSE (0.31), bias (1.76) and R2 (0.68). The recommended prediction model slightly underestimated the actual diameter. The chosen height prediction model is lnD=354-3.98A-1 with RMSE (0.11), bias (0.01) and R2 (0.91). This recommended height prediction model gives very close height estimate to the actual height
Continuum Superpartners
In an exact conformal theory there is no particle. The excitations have
continuum spectra and are called "unparticles" by Georgi. We consider
supersymmetric extensions of the Standard Model with approximate conformal
sectors. The conformal symmetry is softly broken in the infrared which
generates a gap. However, the spectrum can still have a continuum above the gap
if there is no confinement. Using the AdS/CFT correspondence this can be
achieved with a soft wall in the warped extra dimension. When supersymmetry is
broken the superpartners of the Standard Model particles may simply be a
continuum above gap. The collider signals can be quite different from the
standard supersymmetric scenarios and the experimental searches for the
continuum superpartners can be very challenging.Comment: 15 pages, 5 figures, talk at SCGT09 Workshop, Nagoya, Japan, 8-11
Dec, 200
SoC-based biomedical embedded system design of arrhythmia detector
Arrhythmia is an irregular heartbeat where the blood may not be delivered effectively throughout the body and cause sudden cardiac arrest (SCA). Immediate treatment is required to prevent SCA. However, most of the existing electrocardiogram (ECG) monitoring devices are bulky, cost expensive and lack arrhythmia detection and classification system. This paper proposes a front-end on-board graphical interface design of System-on-Chip (SoC) based arrhythmia detector which can be used as a first screening device for cardiac disease patient. The system consists of a knowledge-based arrhythmia classifier which is able to identify three types of arrhythmias which are ventricular fibrillation (VF), premature ventricular contractions (PVCs) and second-degree atrioventricular (AV) block. The system has been evaluated and benchmarked with ECG data from MIT-BIH arrhythmia database. The results show that its accuracy is up to 99.25% with a computation time of 6.385 seconds. It is highly portable and relatively inexpensive for installation in small clinics and home monitoring
Improving Sparse Representation-Based Classification Using Local Principal Component Analysis
Sparse representation-based classification (SRC), proposed by Wright et al.,
seeks the sparsest decomposition of a test sample over the dictionary of
training samples, with classification to the most-contributing class. Because
it assumes test samples can be written as linear combinations of their
same-class training samples, the success of SRC depends on the size and
representativeness of the training set. Our proposed classification algorithm
enlarges the training set by using local principal component analysis to
approximate the basis vectors of the tangent hyperplane of the class manifold
at each training sample. The dictionary in SRC is replaced by a local
dictionary that adapts to the test sample and includes training samples and
their corresponding tangent basis vectors. We use a synthetic data set and
three face databases to demonstrate that this method can achieve higher
classification accuracy than SRC in cases of sparse sampling, nonlinear class
manifolds, and stringent dimension reduction.Comment: Published in "Computational Intelligence for Pattern Recognition,"
editors Shyi-Ming Chen and Witold Pedrycz. The original publication is
available at http://www.springerlink.co
Superconductivity and crystalline electric field effects in the filled skutterudite series Pr(OsRu)Sb
X-ray powder diffraction, magnetic susceptibility , and electrical
resistivity measurements were made on single crystals of the filled
skutterudite series Pr(OsRu)Sb. One end of the series
() is a heavy fermion superconductor with a superconducting critical
temperature K, while the other end () is a conventional
superconductor with K. The lattice constant decreases
approximately linearly with increasing Ru concentration . As Ru (Os) is
substituted for Os (Ru), decreases nearly linearly with substituent
concentration and exhibits a minimum with a value of K at , suggesting that the two types of superconductivity compete with one
another. Crystalline electric field (CEF) effects in and
due to the splitting of the Pr nine-fold degenerate Hund's
rule multiplet are observed throughout the series, with the splitting
between the ground state and the first excited state increasing monotonically
as increases. The fits to the and data are
consistent with a doublet ground state for all values of x,
although reasonable fits can be obtained for a ground state for
values near the end member compounds ( or ).Comment: 10 pages, 8 figures, submitted to Phys. Rev.
Symbiotic Bright Solitary Wave Solutions of Coupled Nonlinear Schrodinger Equations
Conventionally, bright solitary wave solutions can be obtained in
self-focusing nonlinear Schrodinger equations with attractive self-interaction.
However, when self-interaction becomes repulsive, it seems impossible to have
bright solitary wave solution. Here we show that there exists symbiotic bright
solitary wave solution of coupled nonlinear Schrodinger equations with
repulsive self-interaction but strongly attractive interspecies interaction.
For such coupled nonlinear Schrodinger equations in two and three dimensional
domains, we prove the existence of least energy solutions and study the
location and configuration of symbiotic bright solitons. We use Nehari's
manifold to construct least energy solutions and derive their asymptotic
behaviors by some techniques of singular perturbation problems.Comment: to appear in Nonlinearit
Doublet-Triplet Splitting and Fermion Masses with Extra Dimensions
The pseudo-Goldstone boson mechanism for the ``doublet-triplet splitting''
problem of the grand unified theory can be naturally implemented in the
scenario with extra dimensions and branes. The two SU(6) global symmetries of
the Higgs sector are located on two separate branes while the SU(6) gauge
symmetry is in the bulk. After including several vector-like fields in the
bulk, and allowing the most general interactions with their natural strength
(including the higher dimensional ones which may be generated by gravity) which
are consistent with the geometry, a realistic pattern of the Standard Model
fermion masses and mixings can be naturally obtained without any flavor
symmetry. Neutrino masses and mixings required for the solar and atmospheric
neutrino problems can also be accommodated. The geometry of extra dimensions
and branes provides another way to realize the absence of certain interactions
(as required in the pseudo-Goldstone boson mechanism) or the smallness of some
couplings (e.g., the Yukawa couplings between the fermions and the Higgs
bosons), in addition to the usual symmetry arguments.Comment: 16 pages, 4 figures, LaTeX, references and some clarifying remarks
added, to be published in Phys. Rev.
- …