284 research outputs found
Quenching through Dirac and semi-Dirac points in optical Lattices: Kibble-Zurek scaling for anisotropic Quantum-Critical systems
We propose that Kibble-Zurek scaling can be studied in optical lattices by
creating geometries that support, Dirac, Semi-Dirac and Quadratic Band
Crossings. On a Honeycomb lattice with fermions, as a staggered on-site
potential is varied through zero, the system crosses the gapless Dirac points,
and we show that the density of defects created scales as , where
is the inverse rate of change of the potential, in agreement with the
Kibble-Zurek relation. We generalize the result for a passage through a
semi-Dirac point in dimensions, in which spectrum is linear in parallel
directions and quadratic in rest of the perpendicular directions. We
find that the defect density is given by where
and are the dynamical exponents and the correlation
length exponents along the parallel and perpendicular directions, respectively.
The scaling relations are also generalized to the case of non-linear quenching
TREATMENT WITH FERULIC ACID AMELIORATED CISPLATIN‑INDUCED NEPHROTOXICITY AND OXIDATIVE STRESS IN TUMOR BEARING MICE
Cisplatin (Cis) is one of the most widely used cytotoxic therapeutic agents for the treatment of cancer. Overdose of the drug resulted in various side effects of genotoxicity and nephrotoxicity. The toxicity of the drug has been attributed to the generation of oxidative free radicals. The current study aims to explore the effect of Ferulic acid (FA) in ameliorating Cis-induced renal toxicity in tumor bearing Swiss albino mice. Nephrotoxicity was induced in tumor bearing mice by a single dose of Cis (12mg/kg, i.p). Post administration of FA was carried out (100 mg/kg p.o and 200 mg/kg p.o) one hour after Cis administration. Toxicity was measured by analyzing the amount of serum urea, creatinine, and antioxidant status of renal and tumor tissues. Treatment of cisplatin-administered tumor animals with the FA could prevent the drug-induced oxidative damage as evidenced by the decreased levels of lipid peroxidation and enhanced activities of the antioxidants in the renal tissues. The treatment also protected the renal tissues from the toxic effects of Cis by reducing the levels of serum urea and creatinine. FA protected the renal tissues, whereas it enhanced the anticancer efficacy of Cis in tumor tissues. The histopathological observations support that ferulic acid has a protective effect against Cisplatin-induced nephrotoxicity and can be used to improve the chemotherapeutic index of Cisplatin for cancer treatment
Estimation of ferulic acid from selected plant materials by Spectrophotometry and High performance liquid chromatography
Ferulic acid is an abundant phytophenolic compound present in plant cell wall. Ferulic acid possess anticancer, antioxidant, and anti-aging properties. A simple, sensitive and reproducible spectrophotometric method has been developed for quantitative estimation of ferulic acid from selected plant materials such as rice bran, wheat bran and bamboo shoot. The blue coloured chromogen obtained after the reaction was measured at wavelength of 718 nm for ferulic acid against the blank reagent. The chromogen obeyed linearity over the range of 1?g/ml - 8?g/ml. An HPLC method was also developed for the estimation of ferulic acid from selected plant materials
A random fiber bundle with many discontinuities in the threshold distribution
We study the breakdown of a random fiber bundle model (RFBM) with
-discontinuities in the threshold distribution using the global load sharing
scheme. In other words, different classes of fibers identified on the
basis of their threshold strengths are mixed such that the strengths of the
fibers in the class are uniformly distributed between the values
and where . Moreover, there
is a gap in the threshold distribution between and class. We
show that although the critical stress depends on the parameter values of the
system, the critical exponents are identical to that obtained in the recursive
dynamics of a RFBM with a uniform distribution and global load sharing. The
avalanche size distribution (ASD), on the other hand, shows a non-universal,
non-power law behavior for smaller values of avalanche sizes which becomes
prominent only when a critical distribution is approached. We establish that
the behavior of the avalanche size distribution for an arbitrary is
qualitatively similar to a RFBM with a single discontinuity in the threshold
distribution (), especially when the density and the range of threshold
values of fibers belonging to strongest ()-th class is kept identical in
all the cases.Comment: 6 pages, 4 figures, Accepted in Phys. Rev.
Dynamical delocalization of Majorana edge states by sweeping across a quantum critical point
We study the adiabatic dynamics of Majorana fermions across a quantum phase
transition. We show that the Kibble-Zurek scaling, which describes the density
of bulk defects produced during the critical point crossing, is not valid for
edge Majorana fermions. Therefore, the dynamics governing an edge state quench
is nonuniversal and depends on the topological features of the system. Besides,
we show that the localization of Majorana fermions is a necessary ingredient to
guaranty robustness against defect production.Comment: Submitted to the Special Issue on "Dynamics and Thermalization in
Isolated Quantum Many-Body Systems" in New Journal of Physics. Editors:M.
Cazalilla, M. Rigol. New references and some typos correcte
Non-Preemptive Scheduling on Machines with Setup Times
Consider the problem in which n jobs that are classified into k types are to
be scheduled on m identical machines without preemption. A machine requires a
proper setup taking s time units before processing jobs of a given type. The
objective is to minimize the makespan of the resulting schedule. We design and
analyze an approximation algorithm that runs in time polynomial in n, m and k
and computes a solution with an approximation factor that can be made
arbitrarily close to 3/2.Comment: A conference version of this paper has been accepted for publication
in the proceedings of the 14th Algorithms and Data Structures Symposium
(WADS
Adiabatic multicritical quantum quenches: Continuously varying exponents depending on the direction of quenching
We study adiabatic quantum quenches across a quantum multicritical point
(MCP) using a quenching scheme that enables the system to hit the MCP along
different paths. We show that the power-law scaling of the defect density with
the rate of driving depends non-trivially on the path, i.e., the exponent
varies continuously with the parameter that defines the path, up to a
critical value ; on the other hand for , the scaling exponent saturates to a constant value. We show that
dynamically generated and {\it path()-dependent} effective critical
exponents associated with the quasicritical points lying close to the MCP (on
the ferromagnetic side), where the energy-gap is minimum, lead to this
continuously varying exponent. The scaling relations are established using the
integrable transverse XY spin chain and generalized to a MCP associated with a
-dimensional quantum many-body systems (not reducible to two-level systems)
using adiabatic perturbation theory. We also calculate the effective {\it
path-dependent} dimensional shift (or the shift in center of the
impulse region) that appears in the scaling relation for special paths lying
entirely in the paramagnetic phase. Numerically obtained results are in good
agreement with analytical predictions.Comment: 5 pages, 4 figure
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