Frustrated two-dimensional Josephson junction array near incommensurability

To study the properties of frustrated two-dimensional Josephson junction arrays near incommensurability, we examine the current-voltage characteristics of a square proximity-coupled Josephson junction array at a sequence of frustrations f=3/8, 8/21, 0.382 $(\approx (3-\sqrt{5})/2)$, 2/5, and 5/12. Detailed scaling analyses of the current-voltage characteristics reveal approximately universal scaling behaviors for f=3/8, 8/21, 0.382, and 2/5. The approximately universal scaling behaviors and high superconducting transition temperatures indicate that both the nature of the superconducting transition and the vortex configuration near the transition at the high-order rational frustrations f=3/8, 8/21, and 0.382 are similar to those at the nearby simple frustration f=2/5. This finding suggests that the behaviors of Josephson junction arrays in the wide range of frustrations might be understood from those of a few simple rational frustrations.Comment: RevTex4, 4 pages, 4 eps figures, to appear in Phys. Rev.

Mesoscale magnetism at the grain boundaries in colossal magnetoresistive films

We report the discovery of mesoscale regions with distinctive magnetic properties in epitaxial La$_{1-x}$Sr$_{x}$MnO$_{3}$ films which exhibit tunneling-like magnetoresistance across grain boundaries. By using temperature-dependent magnetic force microscopy we observe that the mesoscale regions are formed near the grain boundaries and have a different Curie temperature (up to 20 K {\it higher}) than the grain interiors. Our images provide direct evidence for previous speculations that the grain boundaries in thin films are not magnetically and electronically sharp interfaces. The size of the mesoscale regions varies with temperature and nature of the underlying defect.Comment: 4 pages of text, 4 figure

Seminal plasma and prostaglandin E2 up-regulate fibroblast growth factor 2 expression in endometrial adenocarcinoma cells via E-series prostanoid-2 receptor-mediated transactivation of the epidermal growth factor receptor and extracellular signal-regulated kinase pathway

BACKGROUND: Prostaglandin E(2) (PGE(2)) has been shown to modulate angiogenesis and tumour progression via the E-series prostanoid-2 (EP2) receptor. Endometrial adenocarcinomas may be exposed to endogenous PGE(2) and exogenous PGE(2), present at high concentration in seminal plasma. METHODS: This study investigated fibroblast growth factor 2 (FGF2) mRNA expression and cell signalling in response to seminal plasma or PGE(2), using an endometrial adenocarcinoma (Ishikawa) cell line stably expressing the EP2 receptor (EP2 sense cells) and endometrial adenocarcinoma explants. RESULTS: Seminal plasma and PGE(2) induced a significant up-regulation of FGF2 expression in EP2 sense but not parental untransfected Ishikawa (wild-type) cells (P < 0.05). These effects were inhibited by co-treatment with EP2 receptor antagonist or inhibitors of protein kinase A, c-Src, epidermal growth factor receptor (EGFR) kinase or extracellular signal-regulated kinase (ERK) signalling. The treatment of EP2 sense cells with seminal plasma induced cAMP accumulation and phosphorylation of c-Src, EGFR kinase and ERK via the EP2 receptor. Finally, seminal plasma and PGE(2) significantly increased FGF2 mRNA expression in endometrial adenocarcinoma tissue explants via the EP2 receptor (P < 0.05). CONCLUSIONS: Seminal plasma and PGE(2) can similarly activate FGF2 expression and EP2 receptor signalling in endometrial adenocarcinoma cells. These data highlight the potential for seminal plasma exposure to facilitate tumorigenesis–angiogenesis in endometrial adenocarcinomas in vivo

Evaluation of the Metal Fatigue Solutions Electrochemical Fatigue Sensor System, March 2018

The electrochemical fatigue sensor was developed to detect very small fatigue cracks that are actively growing. To evaluate the fatigue crack capabilities and gain a better understanding of implementation needs, a laboratory test and a field monitoring program were developed to evaluate the EFS system using the CrackChek and FatigueWatch sensors, respectively. The laboratory test program consisted of evaluating the adequacy of Crackchek sensors for crack detection. The Crackchek sensors were installed on a standard steel plate specimen. An electrical discharge machining (EDM) notch was induced in the mid-length of the steel plate and a pair of sensors were installed adjacent to the notch tip. The field monitoring program consisted of evaluating the adequacy of the FatigueWatch sensors for crack detection and the general capabilities of the system for use in field applications. The sensors were installed on the Cherry Creek Bridge near Newton, Iowa, on a sacrificial specimen and on a bridge girder web in a known fatigue-sensitive location. The sacrificial specimen was a standard steel plate exactly the same as the one used for evaluating the CrackChek sensors. The EDM notch was also generated in the edge and mid-length of the specimen and a pair of sensors were installed near the notch tip. After a 13-month data collection and analysis period, no crack formed in either the sacrificial specimen or the bridge girder web where the sensors were installed. In summary, the CrackChek and FatigueWatch sensors perform well for crack detection

The dynamics of quark-gluon plasma and AdS/CFT

In these pedagogical lectures, we present the techniques of the AdS/CFT correspondence which can be applied to the study of real time dynamics of a strongly coupled plasma system. These methods are based on solving gravitational Einstein's equations on the string/gravity side of the AdS/CFT correspondence. We illustrate these techniques with applications to the boost-invariant expansion of a plasma system. We emphasize the common underlying AdS/CFT description both in the large proper time regime where hydrodynamic dynamics dominates, and in the small proper time regime where the dynamics is far from equilibrium. These AdS/CFT methods provide a fascinating arena interrelating General Relativity phenomenae with strongly coupled gauge theory physics.Comment: 35 pages, 3 figures. Lectures at the 5th Aegean summer school, `From gravity to thermal gauge theories: the AdS/CFT correspondence'. To appear in the proceedings in `Lecture Notes in Physics

Hierarchical urchin-like CuxCo3−xO4 spinels as oxygen evolution reaction catalysts in alkaline anion exchange membrane water electrolyzers

In this work, powdered hierarchical CuxCo3−xO4 catalysts were used as catalysts for the oxygen evolution reaction (OER) in an alkaline anion exchange membrane water electrolyzer (AAEMWE). The effect of increasing Cu concentration (x = 0, 0.25, 0.5, 0.75, and 1) on the OER catalysis performance of the spinel Co3O4 was studied. In general, Cu-doped Co3O4 samples performed better than the undoped spinel catalyst. The sample synthesized with Cu-doping at x = 0.75 (CCO-0.75) performed the best among the catalysts tested with an overpotential of 385 mV at 10 mA cm−2 in 1 M KOH, which is 24% lower than that recorded for the undoped Co3O4 sample. An AAEMWE was assembled using CCO-0.75 on Ti gas diffusion layer (GDL), and Pt/C on carbon GDL as the anode, and cathode, respectively. The CCO-0.75||Pt/C cell required only 1.65 V to reach 100 mA cm−2 at 60 ℃ in 1 M KOH

Spectrum of the SU(3) Dirac operator on the lattice: Transition from random matrix theory to chiral perturbation theory

We calculate complete spectra of the Kogut-Susskind Dirac operator on the lattice in quenched SU(3) gauge theory for various values of coupling constant and lattice size. From these spectra we compute the connected and disconnected scalar susceptibilities and find agreement with chiral random matrix theory up to a certain energy scale, the Thouless energy. The dependence of this scale on the lattice volume is analyzed. In the case of the connected susceptibility this dependence is anomalous, and we explain the reason for this. We present a model of chiral perturbation theory that is capable of describing the data beyond the Thouless energy and that has a common range of applicability with chiral random matrix theory.Comment: 8 pages, RevTeX, 15 .eps figure

Four Zero Texture Fermion Mass Matrices in SO(10) GUT

We attempt the integration of the phenomenologically successful four zero texture of fermion mass matrices with the renormalizable SO(10) GUT. The resulting scenario is found to be highly predictive. Firstly, we examine the phenomenological implications of a class of the lepton mass matrices with parallel texture structures and obtain interesting constraints on the parameters of the charged lepton and the neutrino mass matrices. We combine these phenomenological constraints with the constraints obtained from SO(10) GUT to reduce the number of the free parameters and to further constrain the allowed ranges of the free parameters. The solar/atmospheric mixing angles obtained in this analysis are in fairly good agreement with the data.Comment: 14 pages, 3 figures, 1 tabl

Dynamical model and nonextensive statistical mechanics of a market index on large time windows

The shape and tails of partial distribution functions (PDF) for a financial signal, i.e. the S&P500 and the turbulent nature of the markets are linked through a model encompassing Tsallis nonextensive statistics and leading to evolution equations of the Langevin and Fokker-Planck type. A model originally proposed to describe the intermittent behavior of turbulent flows describes the behavior of normalized log-returns for such a financial market index, for small and large time windows, both for small and large log-returns. These turbulent market volatility (of normalized log-returns) distributions can be sufficiently well fitted with a $\chi^2$-distribution. The transition between the small time scale model of nonextensive, intermittent process and the large scale Gaussian extensive homogeneous fluctuation picture is found to be at $ca.$ a 200 day time lag. The intermittency exponent ($\kappa$) in the framework of the Kolmogorov log-normal model is found to be related to the scaling exponent of the PDF moments, -thereby giving weight to the model. The large value of $\kappa$ points to a large number of cascades in the turbulent process. The first Kramers-Moyal coefficient in the Fokker-Planck equation is almost equal to zero, indicating ''no restoring force''. A comparison is made between normalized log-returns and mere price increments.Comment: 40 pages, 14 figures; accepted for publication in Phys Rev

Antihistaminic effect of Bauhinia racemosa leaves

Bauhinia racemosa Lam. (Caesalpiniaceae) leaves have been used in the treatment of asthma traditionally and we therefore undertook this study to scientifically validate its benefit in asthma using suitable animal models. Antihistaminic principles are known to be useful in the treatment of asthma; hence, in the present work, the antihistaminic activity of an ethanol extract of B. racemosa (at a dose of 50 mg/kg, i.p.) was assessed using clonidine-induced catalepsy and haloperidol-induced catalepsy in Swiss albino mice. The results showed that the ethanol extract inhibits clonidine-induced catalepsy but there is no effect on haloperidol-induced catalepsy. This suggests that the inhibition is through an antihistaminic action and that there is no role of dopamine. Hence, we concluded that the ethanol extract has significant antihistaminic activity. The polar constituents in the ethanol extract of leaves of B. racemosa may be responsible for the antihistaminic activity and B. racemosa may therefore have a role in the treatment of asthma