20,266 research outputs found
Quantum speed limit for relativistic spin-0 and spin-1 bosons on commutative and noncommutative planes
Quantum speed limits of relativistic charged spin-0 and spin-1 bosons in the
background of a homogeneous magnetic field are studied on both commutative and
oncommutative planes. We show that, on the commutative plane, the average
speeds of wave packets along the radial direction during the interval in which
a quantum state evolving from an initial state to the orthogonal final one can
not exceed the speed of light, regardless of the intensities of the magnetic
field. However, due to the noncommutativity, the average speeds of the wave
packets on noncommutative plane will exceed the speed of light in vacuum
provided the intensity of the magnetic field is strong enough. It is a clear
signature of violating Lorentz invariance in quantum mechanics region.Comment: 8 pages, no figures. arXiv admin note: text overlap with
arXiv:1702.0316
Efficacy of alternative seating on attention, in-seat behavior, and occupational performance in children with Attention Deficit Hyperactivity Disorder
Currently, there is one systematic review conducted by Gochenour and Poskey7 that synthesize current research evidence regarding alternative seating for students with attention difficulties. A limitation of this review, as noted by the authors, is a lack of a consistent definition of attention difficulty in the studies they included. A systematic review focused on a specific, well-defined diagnosis will better contribute to practice recommendations since these recommendations will be tailored to a clear and comprehensive understanding of the child’s attentional and occupational challenges. The review also included studies of children with autism spectrum disorder (ASD).7 While those with ASD may also have difficulties with attention, in-seat behavior and occupational performance, the underlying mechanism yielding these symptoms may be different than in children with ADHD. Thus, alternative seating may not work in the same way for children with ASD as it would for children with ADHD.7 Thus, a systematic review is needed to examine the evidence from all current studies regarding alternative seating on improving attention, in-seat behavior and occupational performance in students with ADHD to increase evidence-based practice in the field of occupational therapy
Microscopic theory of surface-enhanced Raman scattering in noble-metal nanoparticles
We present a microscopic model for surface-enhanced Raman scattering (SERS)
from molecules adsorbed on small noble-metal nanoparticles. In the absence of
direct overlap of molecular orbitals and electronic states in the metal, the
main enhancement source is the strong electric field of the surface plasmon
resonance in a nanoparticle acting on a molecule near the surface. In small
particles, the electromagnetic enhancement is strongly modified by quantum-size
effects. We show that, in nanometer-sized particles, SERS magnitude is
determined by a competition between several quantum-size effects such as the
Landau damping of surface plasmon resonance and reduced screening near the
nanoparticle surface. Using time-dependent local density approximation, we
calculate spatial distribution of local fields near the surface and enhancement
factor for different nanoparticles sizes.Comment: 8 pages, 6 figures. Considerably extended final versio
Fetching marked items from an unsorted database in NMR ensemble computing
Searching a marked item or several marked items from an unsorted database is
a very difficult mathematical problem. Using classical computer, it requires
steps to find the target. Using a quantum computer, Grover's
algorithm uses steps. In NMR ensemble computing,
Brushweiler's algorithm uses steps. In this Letter, we propose an
algorithm that fetches marked items in an unsorted database directly. It
requires only a single query. It can find a single marked item or multiple
number of items.Comment: 4 pages and 1 figur
Stress intensity factor for an elastic half plane weakend by multiple curved cracks
Modified complex potential with free traction boundary condition is used to formulate the curved crack problem in a half plane elasticity into a singular integral equation. The singular integral equation is solved numerically for the unknown distribution dislocation function. Numerical examples exhibit the stress intensity factor increases as the cracks getting close to each other, and close to the boundary of the half plane
Transcriptional and Post-Transcriptional Regulation of Autophagy
Autophagy is a widely conserved process in eukaryotes that is involved in a series of physiological and pathological events, including development, immunity, neurodegenerative disease, and tumorigenesis. It is regulated by nutrient deprivation, energy stress, and other unfavorable conditions through multiple pathways. In general, autophagy is synergistically governed at the RNA and protein levels. The upstream transcription factors trigger or inhibit the expression of autophagyor lysosome-related genes to facilitate or reduce autophagy. Moreover, a significant number of noncoding RNAs (microRNA, circRNA, and lncRNA) are reported to participate in autophagy regulation. Finally, post-transcriptional modifications, such as RNA methylation, play a key role in controlling autophagy occurrence. In this review, we summarize the progress on autophagy research regarding transcriptional regulation, which will provide the foundations and directions for future studies on this self-eating process
Mixed method for the product integral on the infinite interval
In this note, quadrature formula is constructed for product integral on the infinite interval I(f) = ∫ w(x)f(x)dx, where w(x) is a weight function and f(x) is a smooth decaying function for x > N (large enough) and piecewise discontinuous function of the first kind on the interval a ≤ x ≤ N. For the approximate method we have reduced infinite interval x [a, ∞) into the interval t[0,1] and used the mixed method: Cubic Newton’s divided difference formula on [0, t3) and Romberg method on [t3,1] with equal step size, ti = t0+ih,i=0, …,n, h=1/n, where t0 = 0,tn=1. Error term is obtained for mixed method on different classes of functions. Finally, numerical examples are presented to validate the method presented
Hepatoprotective Activity of Dried- and Fermented-Processed Virgin Coconut Oil
The present study aims to determine the hepatoprotective effect of MARDI-produced virgin coconut oils, prepared by dried- or fermented-processed methods, using the paracetamol-induced liver damage in rats. Liver injury induced by 3 g/kg paracetamol increased the liver weight per 100 g bodyweight indicating liver damage. Histological observation also confirms liver damage indicated by the presence of inflammations and necrosis on the respective liver section. Interestingly, pretreatment of the rats with 10, but not 1 and 5, mL/kg of both VCOs significantly (P < .05) reduced the liver damage caused by the administration of paracetamol, which is further confirmed by the histological findings. In conclusion, VCO possessed hepatoprotective effect that requires further in-depth study
Optical study on doped polyaniline composite films
Localization driven by disorder has a strong influence on the conducting
property of conducting polymer. A class of authors hold the opinion that
disorder in the material is homogeneous and conducting polymer is disordered
metal close to Anderson-Mott Metal-Insulator transition, while others treat the
disorder as inhomogeneous and have the conclusion that conducting polymer is a
composite of ordered metallic regions and disordered insulating regions. The
morphology of conducting polymers is an important factor that have influence on
the type and extent of disorder. Different protonic acids used as dopants and
moisture have affection on polymer chain arrangement and interchain
interactions. A PANI-CSA film, two PANI-CSA/PANI-DBSA composite films with
different dopants ratio, and one of the composite films with different moisture
content are studied. Absolute reflectivity measurements are performed on the
films. Optical conductivity and the real part of dielectric function are
calculated by Kramers-Kronig(KK) relations. and
derivate from simple Drude model in low frequency range
and tendencies of the three sample are different and non-monotonic. The
Localization Modified Drude model(LMD) in the framework of Anderson-Mott theory
can not give a good fit to the experimental data. By introducing a distribution
of relaxation time into LMD, reasonable fits for all three samples are
obtained. This result supports the inhomogeneous picture.Comment: 6 figures, 7 page
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