2,794 research outputs found
Light-cone Quantum Mechanics of the Eleven-dimensional Superparticle
The linearized interactions of eleven-dimensional supergravity are obtained
in a manifestly supersymmetric light-cone gauge formalism. These vertices are
used to calculate certain one-loop processes involving external gravitini,
antisymmetric three-form potentials and gravitons, thereby determining some
protected terms in the effective action of M-theory compactified on a
two-torus.Comment: 31 pages, harvmac (b); A minor TeX error correcte
Electron-boson spectral density of LiFeAs obtained from optical data
We analyze existing optical data in the superconducting state of LiFeAs at 4 K, to recover its electron-boson spectral density. A maximum entropy
technique is employed to extract the spectral density from
the optical scattering rate. Care is taken to properly account for elastic
impurity scattering which can importantly affect the optics in an -wave
superconductor, but does not eliminate the boson structure. We find a robust
peak in centered about 8.0 meV or 5.3 (with 17.6 K). Its position in energy agrees well with a similar
structure seen in scanning tunneling spectroscopy (STS). There is also a peak
in the inelastic neutron scattering (INS) data at this same energy. This peak
is found to persist in the normal state at 23 K. There is evidence that
the superconducting gap is anisotropic as was also found in low temperature
angular resolved photoemission (ARPES) data.Comment: 17 pages, 6 figure
Two loops in eleven dimensions
The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus, T^2, is analyzed in detail. The Schwinger parameter integrations are re-expressed as integration over the moduli space of a second torus, \hat T^2, which enables the leading low-momentum contribution to be evaluated in terms of maps of \hat T^2 into T^2. The ultraviolet divergences associated with boundaries of moduli space are regularized in a manner that is consistent with the expected duality symmetries of string theory. This leads to an exact expression for terms of order contraction of four Weyl tensors), thereby extending earlier results for the R^4 term that were based on the one-loop eleven-dimensional amplitude. Precise agreement is found with terms in type IIA and IIB superstring theory that arise from the low energy expansion of the tree-level and one-loop string amplitudes and predictions are made for the coefficients of certain two-loop string theory terms as well as for an infinite set of D-instanton contributions. The contribution at the next order in the derivative expansion, \partial^6 R^4, is problematic, which may indicate that it mixes with higher-loop effects in eleven-dimensional supergravity
Dynamic behavior of driven interfaces in models with two absorbing states
We study the dynamics of an interface (active domain) between different
absorbing regions in models with two absorbing states in one dimension;
probabilistic cellular automata models and interacting monomer-dimer models.
These models exhibit a continuous transition from an active phase into an
absorbing phase, which belongs to the directed Ising (DI) universality class.
In the active phase, the interface spreads ballistically into the absorbing
regions and the interface width diverges linearly in time. Approaching the
critical point, the spreading velocity of the interface vanishes algebraically
with a DI critical exponent. Introducing a symmetry-breaking field that
prefers one absorbing state over the other drives the interface to move
asymmetrically toward the unpreferred absorbing region. In Monte Carlo
simulations, we find that the spreading velocity of this driven interface shows
a discontinuous jump at criticality. We explain that this unusual behavior is
due to a finite relaxation time in the absorbing phase. The crossover behavior
from the symmetric case (DI class) to the asymmetric case (directed percolation
class) is also studied. We find the scaling dimension of the symmetry-breaking
field .Comment: 5 pages, 5 figures, Revte
TAZ Suppresses NFAT5 Activity through Tyrosine Phosphorylation
Transcriptional coactivator with PDZ-binding motif (TAZ) physically interacts with a variety of transcription factors and modulates their activities involved in cell proliferation and mesenchymal stem cell differentiation. TAZ is highly expressed in the kidney, and a deficiency of this protein results in multiple renal cysts and urinary concentration defects; however, the molecular functions of TAZ in renal cells remain largely unknown. In this study, we examined the effects of osmotic stress on TAZ expression and activity in renal cells. We found that hyperosmotic stress selectively increased protein phosphorylation at tyrosine 316 of TAZ and that this was enhanced by c-Abl activation in response to hyperosmotic stress. Interestingly, phosphorylated TAZ physically interacted with nuclear factor of activated T cells 5 (NFAT5), a major osmoregulatory transcription factor, and subsequently suppressed DNA binding and transcriptional activity of NFAT5. Furthermore, TAZ deficiency elicited an increase in NFAT5 activity in vitro and in vivo, which then reverted to basal levels following restoration of wild-type TAZ but not mutant TAZ (Y316F). Collectively, the data suggest that TAZ modulates cellular responses to hyperosmotic stress through fine-tuning of NFAT5 activity via tyrosine phosphorylation.open3
Branching and annihilating Levy flights
We consider a system of particles undergoing the branching and annihilating
reactions A -> (m+1)A and A + A -> 0, with m even. The particles move via
long-range Levy flights, where the probability of moving a distance r decays as
r^{-d-sigma}. We analyze this system of branching and annihilating Levy flights
(BALF) using field theoretic renormalization group techniques close to the
upper critical dimension d_c=sigma, with sigma<2. These results are then
compared with Monte-Carlo simulations in d=1. For sigma close to unity in d=1,
the critical point for the transition from an absorbing to an active phase
occurs at zero branching. However, for sigma bigger than about 3/2 in d=1, the
critical branching rate moves smoothly away from zero with increasing sigma,
and the transition lies in a different universality class, inaccessible to
controlled perturbative expansions. We measure the exponents in both
universality classes and examine their behavior as a function of sigma.Comment: 9 pages, 4 figure
Mechanism of Cisplatin-Induced Cytotoxicity Is Correlated to Impaired Metabolism Due to Mitochondrial ROS Generation
The chemotherapeutic use of cisplatin is limited by its severe side effects. In this study, by conducting different omics data analyses, we demonstrated that cisplatin induces cell death in a proximal tubular cell line by suppressing glycolysis-and tricarboxylic acid (TCA)/mitochondria-related genes. Furthermore, analysis of the urine from cisplatin-treated rats revealed the lower expression levels of enzymes involved in glycolysis, TCA cycle, and genes related to mitochondrial stability and confirmed the cisplatin-related metabolic abnormalities. Additionally, an increase in the level of p53, which directly inhibits glycolysis, has been observed. Inhibition of p53 restored glycolysis and significantly reduced the rate of cell death at 24 h and 48 h due to p53 inhibition. The foremost reason of cisplatin-related cytotoxicity has been correlated to the generation of mitochondrial reactive oxygen species (ROS) that influence multiple pathways. Abnormalities in these pathways resulted in the collapse of mitochondrial energy production, which in turn sensitized the cells to death. The quenching of ROS led to the amelioration of the affected pathways. Considering these observations, it can be concluded that there is a significant correlation between cisplatin and metabolic dysfunctions involving mROS as the major player.116224Ysciescopu
Does hardcore interaction change absorbing type critical phenomena?
It has been generally believed that hardcore interaction is irrelevant to
absorbing type critical phenomena because the particle density is so low near
an absorbing phase transition. We study the effect of hardcore interaction on
the N species branching annihilating random walks with two offspring and report
that hardcore interaction drastically changes the absorbing type critical
phenomena in a nontrivial way. Through Langevin equation type approach, we
predict analytically the values of the scaling exponents, in one dimension for all N > 1. Direct numerical
simulations confirm our prediction. When the diffusion coefficients for
different species are not identical, and vary
continuously with the ratios between the coefficients.Comment: 4 pages, 1 figur
Phosphate uptake and growth characteristics of transgenic rice with phosphate transporter 1 (OsPT1) gene overexpression under high phosphate soils
Farmers have used phosphate fertilizer to provide sufficient yields. However, overuse of phosphorus accumulate in soil and causes soil and water pollution. We evaluated the phosphate acquisition and growth characteristics of OsPT1 transgenic rice (OsPT1-OX, over-expressing the high affinity phosphate transporter 1) in high phosphate soils with different level of nitrogen fertilizer treatment to investigate its removal ability of excessive phosphate from soil. OsPT1-OX had shorter culm length but more tillers than those of wild-type plants in each soil conditions. Phosphate content per dry weight of OsPT1-OX was 1.8 times higher than that of wild-type under control fertilizer treated conditions. Although the dry weight of OsPT1-OX was not different from that of wild-type plants, whole plant phosphate content was 1.7 times higher than that of wild-type plants under control fertilizer conditions. Tiller number and phosphate content per dry weight of wild-type plants increased following high levels of phosphate application, but did not change following additional nitrogen application. Tiller number and phosphate content per dry weight of OsPT1-OX did not also change under the high phosphate condition, but increased following nitrogen application under similar conditions. Whole plant phosphate content was also highest under high nitrogen and high phosphate application conditions. These results suggest that OsPT1-OX may reduce phosphate content in soils containing excess phosphate and may be further effective under high nitrogen condition.Key words: Phosphate content, fertilizer treatment, phosphate transporter, rice, soil
Assessment of radiofrequency electromagnetic field exposure from personal measurements considering the body shadowing effect in Korean children and parents
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