6,671 research outputs found
Sensitive Chemical Compass Assisted by Quantum Criticality
The radical-pair-based chemical reaction could be used by birds for the
navigation via the geomagnetic direction. An inherent physical mechanism is
that the quantum coherent transition from a singlet state to triplet states of
the radical pair could response to the weak magnetic field and be sensitive to
the direction of such a field and then results in different photopigments in
the avian eyes to be sensed. Here, we propose a quantum bionic setup for the
ultra-sensitive probe of a weak magnetic field based on the quantum phase
transition of the environments of the two electrons in the radical pair. We
prove that the yield of the chemical products via the recombination from the
singlet state is determined by the Loschmidt echo of the environments with
interacting nuclear spins. Thus quantum criticality of environments could
enhance the sensitivity of the detection of the weak magnetic field.Comment: 4 pages, 3 figure
Trapped interacting two-component bosons
In this paper we solve one dimensional trapped SU(2) bosons with repulsive
-function interaction by means of Bethe-ansatz method. The features of
ground state and low-lying excited states are studied by numerical and analytic
methods. We show that the ground state is an isospin "ferromagnetic" state
which differs from spin-1/2 fermions system. There exist three quasi-particles
in the excitation spectra, and both holon-antiholon and holon-isospinon
excitations are gapless for large systems. The thermodynamics equilibrium of
the system at finite temperature is studied by thermodynamic Bethe ansatz. The
thermodynamic quantities, such as specific heat etc. are obtained for the case
of strong coupling limit.Comment: 15 pages, 9 figure
Extraction of differential expressing aphid-resistance genes of sorghum (Sorghum bicolor L. Monech) and construction of suppression subtractive hybridization (SSH) library
Experiments were conducted for the extraction of differential expressing aphid-resistance genes of sorghum (Sorghum bicolor L. Monech) in the experimental laboratories and fields of Hebei Agricultural University, China and Shenyang Agricultural University, Liaoning Province, China, during 2010 to 2011 and suppression subtractive hybridization (SSH) library was constructed. The seeds of two sorghum varieties (Henong-16 and Qian-3) were grown and aphids were infested through natural and artificial way on sorghum seedlings (10-day old) with a paint brush. Total mRNA was isolated from fresh leaves samples using Trizol reagent and plant RNA mate (TAKARA). Integrity of RNA was confirmed by 1.2% agarose gel electrophoresis. SSH was performed using PCR-Select cDNA subtraction kit user manual according to the manufacturer’s instruction (Clontech Laboratories, Inc, USA). cDNA that contained specific (differentially expressed) transcripts were denoted as tester and the reference cDNA as driver. Tester and driver cDNAs were hybridized after two rounds of subtractive suppression PCR and the pMD18-T vector (TAKARA, Dalian, China). After preliminary screening by subtractive hybridization, plasmid restriction enzyme digestion, colony PCR for 100 forward and 100 reverse clones were sequenced by two-way hybridization using Mega BACE1000 to obtain better quality of 200 expressed sequence tag (EST) sequences. Cross-match software and ClustalW2 were used to obtain vector sequence shielding and multiple comparisons. Using BLAST at NCBI database for homology comparisons, it was concluded that a number of EST sequences which had different degrees of homology with known proteins or genes and another six EST sequences did not have any significant homology in the database. These sequences might have representation for new and unknown genes, or higher variability of non-coding region cDNA sequences.Key words: Extraction, sorghum, SSH, aphid-resistance genes
Decay of Loschmidt Echo Enhanced by Quantum Criticality
We study the transition of a quantum system from a pure state to a mixed
one, which is induced by the quantum criticality of the surrounding system
coupled to it. To characterize this transition quantitatively, we carefully
examine the behavior of the Loschmidt echo (LE) of modelled as an Ising
model in a transverse field, which behaves as a measuring apparatus in quantum
measurement. It is found that the quantum critical behavior of strongly
affects its capability of enhancing the decay of LE: near the critical value of
the transverse field entailing the happening of quantum phase transition, the
off-diagonal elements of the reduced density matrix describing vanish
sharply.Comment: 4 pages, 3 figure
Finite-Temperature Scaling of Magnetic Susceptibility and Geometric Phase in the XY Spin Chain
We study the magnetic susceptibility of 1D quantum XY model, and show that
when the temperature approaches zero, the magnetic susceptibility exhibits the
finite-temperature scaling behavior. This scaling behavior of the magnetic
susceptibility in 1D quantum XY model, due to the quantum-classical mapping,
can be easily experimentally tested. Furthermore, the universality in the
critical properties of the magnetic susceptibility in quantum XY model is
verified. Our study also reveals the close relation between the magnetic
susceptibility and the geometric phase in some spin systems, where the quantum
phase transitions are driven by an external magnetic field.Comment: 6 pages, 4 figures, get accepted for publication by J. Phys. A: Math.
Theo
Heme oxygenase-1 enhances renal mitochondrial transport carriers and cytochrome C oxidase activity in experimental diabetes
Up-regulation of heme oxygenase (HO-1) by either cobalt protoporphyrin
(CoPP) or human gene transfer improves vascular and
renal function by several mechanisms, including increases in antioxidant
levels and decreases in reactive oxygen species (ROS) in
vascular and renal tissue. The purpose of the present study was to
determine the effect of HO-1 overexpression on mitochondrial
transporters, cytochrome c oxidase, and anti-apoptotic proteins in
diabetic rats (streptozotocin, (STZ)-induced type 1 diabetes). Renal
mitochondrial carnitine, deoxynucleotide, and ADP/ATP carriers
were significantly reduced in diabetic compared with nondiabetic
rats (p<0.05). The citrate carrier was not significantly decreased in
diabetic tissue. CoPP administration produced a robust increase in
carnitine, citrate, deoxynucleotide, dicarboxylate, and ADP/ATP
carriers and no significant change in oxoglutarate and aspartate/
glutamate carriers. The increase in mitochondrial carriers (MCs)
was associated with a significant increase in cytochrome c oxidase
activity. The administration of tin mesoporphyrin (SnMP), an
inhibitor of HO-1 activity, prevented the restoration of MCs in diabetic
rats. Human HO-1 cDNA transfer into diabetic rats increased
both HO-1 protein and activity, and restored mitochondrial ADP/
ATP and deoxynucleotide carriers. The increase in HO-1 by CoPP
administration was associated with a significant increase in the
phosphorylation of AKT and levels of BcL-XL proteins. These
observations in experimental diabetes suggest that the cytoprotective
mechanism of HO-1 against oxidative stress involves an
increase in the levels of MCs and anti-apoptotic proteins as well as
in cytochrome c oxidase activity
Dynamics of lattice spins as a model of arrhythmia
We consider evolution of initial disturbances in spatially extended systems
with autonomous rhythmic activity, such as the heart. We consider the case when
the activity is stable with respect to very smooth (changing little across the
medium) disturbances and construct lattice models for description of
not-so-smooth disturbances, in particular, topological defects; these models
are modifications of the diffusive XY model. We find that when the activity on
each lattice site is very rigid in maintaining its form, the topological
defects - vortices or spirals - nucleate a transition to a disordered,
turbulent state.Comment: 17 pages, revtex, 3 figure
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