35 research outputs found
Density of defects and the scaling law of the entanglement entropy in quantum phase transition of one dimensional spin systems induced by a quench
We have studied quantum phase transition induced by a quench in different one
dimensional spin systems. Our analysis is based on the dynamical mechanism
which envisages nonadiabaticity in the vicinity of the critical point. This
causes spin fluctuation which leads to the random fluctuation of the Berry
phase factor acquired by a spin state when the ground state of the system
evolves in a closed path. The two-point correlation of this phase factor is
associated with the probability of the formation of defects. In this framework,
we have estimated the density of defects produced in several one dimensional
spin chains. At the critical region, the entanglement entropy of a block of
spins with the rest of the system is also estimated which is found to increase
logarithmically with . The dependence on the quench time puts a constraint
on the block size . It is also pointed out that the Lipkin-Meshkov-Glick
model in point-splitting regularized form appears as a combination of the XXX
model and Ising model with magnetic field in the negative z-axis. This unveils
the underlying conformal symmetry at criticality which is lost in the sharp
point limit. Our analysis shows that the density of defects as well as the
scaling behavior of the entanglement entropy follows a universal behavior in
all these systems.Comment: 4 figures, Accepted in Phys. Rev.
Quantum Cournot equilibrium for the Hotelling-Smithies model of product choice
This paper demonstrates the quantization of a spatial Cournot duopoly model
with product choice, a two stage game focusing on non-cooperation in locations
and quantities. With quantization, the players can access a continuous set of
strategies, using continuous variable quantum mechanical approach. The presence
of quantum entanglement in the initial state identifies a quantity equilibrium
for every location pair choice with any transport cost. Also higher profit is
obtained by the firms at Nash equilibrium. Adoption of quantum strategies
rewards us by the existence of a larger quantum strategic space at equilibrium.Comment: 13 pages, 6 tables, 8 figure
A statistical method for excluding non-variable CpG sites in high-throughput DNA methylation profiling
<p>Abstract</p> <p>Background</p> <p>High-throughput DNA methylation arrays are likely to accelerate the pace of methylation biomarker discovery for a wide variety of diseases. A potential problem with a standard set of probes measuring the methylation status of CpG sites across the whole genome is that many sites may not show inter-individual methylation variation among the biosamples for the disease outcome being studied. Inclusion of these so-called "non-variable sites" will increase the risk of false discoveries and reduce statistical power to detect biologically relevant methylation markers.</p> <p>Results</p> <p>We propose a method to estimate the proportion of non-variable CpG sites and eliminate those sites from further analyses. Our method is illustrated using data obtained by hybridizing DNA extracted from the peripheral blood mononuclear cells of 311 samples to an array assaying 1505 CpG sites. Results showed that a large proportion of the CpG sites did not show inter-individual variation in methylation.</p> <p>Conclusions</p> <p>Our method resulted in a substantial improvement in association signals between methylation sites and outcome variables while controlling the false discovery rate at the same level.</p
Searching for VHE gamma-ray emission associated with IceCube neutrino alerts using FACT, H.E.S.S., MAGIC, and VERITAS
The realtime follow-up of neutrino events is a promising approach to searchfor astrophysical neutrino sources. It has so far provided compelling evidencefor a neutrino point source: the flaring gamma-ray blazar TXS 0506+056 observedin coincidence with the high-energy neutrino IceCube-170922A detected byIceCube. The detection of very-high-energy gamma rays (VHE, ) from this source helped establish the coincidence andconstrained the modeling of the blazar emission at the time of the IceCubeevent. The four major imaging atmospheric Cherenkov telescope arrays (IACTs) -FACT, H.E.S.S., MAGIC, and VERITAS - operate an active follow-up program oftarget-of-opportunity observations of neutrino alerts sent by IceCube. Thisprogram has two main components. One are the observations of known gamma-raysources around which a cluster of candidate neutrino events has been identifiedby IceCube (Gamma-ray Follow-Up, GFU). Second one is the follow-up of singlehigh-energy neutrino candidate events of potential astrophysical origin such asIceCube-170922A. GFU has been recently upgraded by IceCube in collaborationwith the IACT groups. We present here recent results from the IACT follow-upprograms of IceCube neutrino alerts and a description of the upgraded IceCubeGFU system.<br
Geomagnetic storm-time scintillation study in Antarctica - A comparison of model and observation
Haplotype Analysis of Genomic Polymorphisms in and Around the Myotonic Dystrophy Locus in Diverse Populations of India
The frequencies of haplotypes based upon the
(CTG)n repeat and three other biallelic markers in and
around the myotonic dystrophy (DM) locus were estimated
in 13 ethnically, linguistically and geographically
diverse sub-populations of India. The range of CTG repeats
in caste populations was 5–31, while in tribal populations
the range was shorter (5–23). Extensive variation
in frequencies of large (CTG)n alleles (≥18 repeats) was
found in Indian populations. The implications of this finding
on DM epidemiology are discussed. Haplotype diversity
was found to be very high in most populations. The
majority of the Indian DM patients carried a haplotype
that is commonly found among DM patients globally; this
is the most common haplotype in the class of large (≥18
repeats) CTG alleles. However, one haplotype was found
to be present in particularly high frequency in Indian populations; this haplotype was also found among Indian DM
patients. This haplotype may be a characteristic of Indian
and possibly of other East Asian populations
Magnetic-field dependence of the entanglement entropy of one-dimensional spin systems in quantum phase transitions induced by a quench
Structure-Based Energetics of Stop Codon Recognition by Eukaryotic Release Factor
In translation termination,
the eukaryotic release factor (eRF1)
recognizes mRNA stop codons (UAA, UAG, or UGA) in a ribosomal A site
and triggers release of the nascent polypeptide chain from P-site
tRNA. eRF1 is highly selective for U in the first position and a combination
of purines (except two consecutive guanines, i.e., GG) in the second
and third positions. Eukaryotes decode all three stop codons with
a single release factor eRF1, instead of two (RF1 and RF2), in bacteria.
Furthermore, unlike bacterial RF1/RF2, eRF1 stabilizes the compact
U-turn mRNA configuration in the ribosomal A site by accommodating
four nucleotides instead of three. Despite the available cryo-EM structures
(resolution ∼3.5–3.8 Å), the energetic principle
for eRF1 selectivity toward a stop codon remains a fundamentally unsolved
problem. Using cryo-EM structures of eukaryotic translation termination
complexes as templates, we carried out molecular dynamics free energy
simulations of cognate and near-cognate complexes to quantitatively
address the energetics of stop codon recognition by eRF1. Our results
suggest that eRF1 has a higher discriminatory power against sense
codons, compared to that reported earlier for RF1/RF2. The compact
mRNA formed specific intra-mRNA interactions, which itself contributed
to stop codon specificity. Furthermore, the specificity is enhanced
by the loss of protein–mRNA interactions and, most importantly,
by desolvation of the incorrect codons in the near-cognate complexes.
Our work provides a clue to how eRF1 discriminates between cognate
and near-cognate codons during protein synthesis