7,745 research outputs found
Fermion Resonances on a Thick Brane with a Piecewise Warp Factor
In this paper, we mainly investigate the problems of resonances of massive KK
fermions on a single scalar constructed thick brane with a piecewise warp
factor matching smoothly. The distance between two boundaries and the other
parameters are determined by one free parameter through three junction
conditions. For the generalized Yukawa coupling
with odd , the mass eigenvalue , width , lifetime
, and maximal probability of fermion resonances are obtained.
Our numerical calculations show that the brane without internal structure also
favors the appearance of resonant states for both left- and right-handed
fermions. The scalar-fermion coupling and the thickness of the brane influence
the resonant behaviors of the massive KK fermions.Comment: V3: 15 pages, 7 figures, published versio
Multi-layer holographic bifurcative neural network system for real-time adaptive EOS data analysis
Optical data processing techniques have the inherent advantage of high data throughout, low weight and low power requirements. These features are particularly desirable for onboard spacecraft in-situ real-time data analysis and data compression applications. The proposed multi-layer optical holographic neural net pattern recognition technique will utilize the nonlinear photorefractive devices for real-time adaptive learning to classify input data content and recognize unexpected features. Information can be stored either in analog or digital form in a nonlinear photorefractive device. The recording can be accomplished in time scales ranging from milliseconds to microseconds. When a system consisting of these devices is organized in a multi-layer structure, a feed forward neural net with bifurcating data classification capability is formed. The interdisciplinary research will involve the collaboration with top digital computer architecture experts at the University of Southern California
Thick branes with a nonminimally coupled bulk-scalar field
In this paper, we investigate thick branes with a nonminimally coupled
background scalar field, whose solution is a single-kink or a double-kink. The
effects of the nonminimal coupling constant on the structure of the thick
branes and the localization of gravity, fermions, scalars and vectors are
discussed. It is shown that each brane will split into two sub-branes as
increasing the nonminimal coupling constant . By investigating the tensor
perturbation equations of gravity and the general covariant Dirac equation of
fermions, we find that both the gravity zero mode and left-chiral fermion zero
mode are localized at the center of the single-kink branes and localized
between the two sub-branes generated by the double-kink, which indicates that
the constant does not effect the localization of these zero modes.
However, the zero mode of scalars is localized on each sub-brane (for both
single-kink and double-kink branes) when is larger than its critical
value . The effects of the nonminimal coupling constant on the
resonances of gravity and fermions with finite lifetime on the branes are also
discussed.Comment: V2: 33 pages, 17 figures, 3 tables, published versio
Biomarker Exploration in Human Peripheral Blood Mononuclear Cells for Monitoring Sulforaphane Treatment Responses in Autism Spectrum Disorder
Autism Spectrum Disorder (ASD) is one of the most common neurodevelopmental disorders with no drugs treating the core symptoms and no validated biomarkers for clinical use. The multi-functional phytochemical sulforaphane affects many of the biochemical abnormalities associated with ASD. We investigated potential molecular markers from three ASD-associated physiological pathways that can be affected by sulforaphane: redox metabolism/oxidative stress; heat shock response; and immune dysregulation/inflammation, in peripheral blood mononuclear cells (PBMCs) from healthy donors and patients with ASD. We first analyzed the mRNA levels of selected molecular markers in response to sulforaphane ex vivo treatment in PBMCs from healthy donors by real-time quantitative PCR. All of the tested markers showed quantifiability, accuracy and reproducibility. We then compared the expression levels of those markers in PBMCs taken from ASD patients in response to orally-delivered sulforaphane. The mRNA levels of cytoprotective enzymes (NQO1, HO-1, AKR1C1), and heat shock proteins (HSP27 and HSP70), increased. Conversely, mRNA levels of pro-inflammatory markers (IL-6, IL-1beta, COX-2 and TNF-alpha) decreased. Individually none is sufficiently specific or sensitive, but when grouped by function as two panels, these biomarkers show promise for monitoring pharmacodynamic responses to sulforaphane in both healthy and autistic humans, and providing guidance for biomedical interventions
Si-based anode materials for lithium rechargeable batteries
Silicon is a very promising candidate to replace graphite as the anode in Li-ion batteries because of its very high theoretical capacity, relatively low cost and low toxicity. However, it has not yet made its way into commercial cells. This review highlights recent progress on Si-based anode materials for lithium rechargeable batteries
Transport critical current density in Fe-sheathed nano-SiC doped MgB2 wires
The nano-SiC doped MgB2/Fe wires were fabricated using a powder-in-tube
method and an in-situ reaction process. The depression of Tc with increasing
SiC doping level remained rather small due to the counterbalanced effect of Si
and C co-doping. The high level SiC co-doping allowed creation of the
intra-grain defects and nano-inclusions, which act as effective pinning
centers, resulting in a substantial enhancement in the Jc(H) performance. The
transport Jc for all the wires is comparable to the magnetic Jc at higher
fields despite the low density of the samples and percolative nature of
current. The transport Ic for the 10wt% SiC doped MgB2/Fe reached 660A at 5K
and 4.5T (Jc = 133,000A/cm2) and 540A at 20K and 2T (Jc = 108,000A/cm2). The
transport Jc for the 10wt% SiC doped MgB2 wire is more than an order of
magnitude higher than for the state-the-art Fe-sheathed MgB2 wire reported to
date at 5K and 10T and 20K and 5T respectively. There is a plenty of room for
further improvement in Jc as the density of the current samples is only 50%.Comment: 4 pages, 7 figures, presented at ASC 2002, Housto
Spin alignments of vector mesons in deeply inelastic lepton-nucleon scattering
We extend the calculations of the spin alignments of vector mesons in
annihilation in a recent Rapid Communication to deeply inelastic
lepton-nucleon scatterings. We present the results for different mesons in the
current fragmentation regions of at high energies
and at both high and low energies. We also present
the predictions for at NOMAD energies in the
target fragmentation region using a valence quark model.Comment: 4 pages, 6 figures; to appear in Phys. Rev.
Lateral Sharpening of Cortical Frequency Tuning by Approximately Balanced Inhibition
SummaryCortical inhibition plays an important role in shaping neuronal processing. The underlying synaptic mechanisms remain controversial. Here, in vivo whole-cell recordings from neurons in the rat primary auditory cortex revealed that the frequency tuning curve of inhibitory input was broader than that of excitatory input. This results in relatively stronger inhibition in frequency domains flanking the preferred frequencies of the cell and a significant sharpening of the frequency tuning of membrane responses. The less selective inhibition can be attributed to a broader bandwidth and lower threshold of spike tonal receptive field of fast-spike inhibitory neurons than nearby excitatory neurons, although both types of neurons receive similar ranges of excitatory input and are organized into the same tonotopic map. Thus, the balance between excitation and inhibition is only approximate, and intracortical inhibition with high sensitivity and low selectivity can laterally sharpen the frequency tuning of neurons, ensuring their highly selective representation
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