bluuebunny/crossref_metadata_2025 huggingface dataset:
MOMENTUM AND HAMILTONIAN IN COMPLEX ACTION THEORY
Authors: NAGAO KEIICHI , NIELSEN HOLGER BECH
Published: May 2012

In the complex action theory (CAT) we explicitly examine how the momentum and Hamiltonian are defined from the Feynman path integral (FPI) point of view based on the complex coordinate formalism of our foregoing paper. After reviewing the formalism briefly, we describe in FPI with a Lagrangian the time development of a ξ-parametrized wave function, which is a solution to an eigenvalue problem of a momentum operator. Solving this eigenvalue problem, we derive the momentum and Hamiltonian. Oppositely, starting from the Hamiltonian we derive the Lagrangian in FPI, and we are led to the momentum relation again via the saddle point for p. This study confirms that the momentum and Hamiltonian in the CAT have the same forms as those in the real action theory. We also show the third derivation of the momentum relation via the saddle point for q.
NONTRIVIAL GHOSTS AND SECOND-CLASS CONSTRAINTS
Authors: CHISHTIE FARRUKH , McKEON D. G. C.
Published: May 2012

In a model in which a vector gauge field [Formula: see text] is coupled to an antisymmetric tensor field [Formula: see text] possessing a pseudoscalar mass, it has been shown that all physical degrees of freedom reside in the vector field. Upon quantizing this model using the Faddeev–Popov procedure, explicit calculation of the two-point functions 〈ϕϕ〉 and 〈Wϕ〉 at one-loop order seems to have yielded the puzzling result that the effective action generated by radiative effects has more physical degrees of freedom than the original classical action. In this paper we point out that this is not in fact a real effect, but rather appears to be a consequence of having ignored a "ghost" field arising from the contribution to the measure in the path integral arising from the presence of nontrivial second-class constraints. These ghost fields couple to the fields [Formula: see text] and [Formula: see text], which makes them distinct from other models involving ghosts arising from second-class constraints (such as massive Yang–Mills (YM) models) that have been considered, as in these other models such ghosts decouple. As an alternative to dealing with second-class constraints, we consider introducing a "Stueckelberg field" to eliminate second-class constraints in favor of first-class constraints and examine if it is possible to then use the Faddeev–Popov quantization procedure. In the Proca model, introduction of the Stueckelberg vector is equivalent to the Batalin–Fradkin–Tyutin (BFT) approach to converting second-class constraints to being first-class through the introduction of new variables. However, introduction of a Stueckelberg vector is not equivalent to the BFT approach for the vector–tensor model. In an appendix, the BFT procedure is applied to the pure tensor model and a novel gauge invariance is found. In addition, we also consider extending the Hamiltonian so that half of the second-class constraints become first-class and the other half become associated gauge conditions. We also find for this tensor-vector theory that when converting the phase space path integral to the configuration space path integral, a nontrivial contribution to the measure arises that is not manifestly covariant and which is not simply due to the presence of second-class constraints.
ON SUPERLUMINAL FERMIONS WITHIN THE SECOND DERIVATIVE EQUATION
Authors: KRUGLOV S. I.
Published: May 2012

We postulate the second-order derivative equation with four parameters for spin-1/2 fermions possessing two mass states. For some choice of parameters fermions propagate with the superluminal speed. Thus, the novel tachyonic equation is suggested. The relativistic 20-component first-order wave equation is formulated and projection operators extracting states with definite energy and spin projections are obtained. The Lagrangian formulation of the first-order equation is presented and the electric current and energy–momentum tensor are found. The minimal and nonminimal electromagnetic interactions of fermions are considered and Schrödinger's form of the equation and the quantum-mechanical Hamiltonian are obtained. The canonical quantization of the field in the first-order formalism is performed and we find the vacuum expectation of chronological pairing of operators.
PROBABILITY-BASED DESIGN OPTIMIZATION OF DYNAMIC SYSTEMS
Authors: SEECHARAN TURUNA S. , SAVAGE GORDON J.
Published: May 2012

The mechanistic model of a dynamic system is often so complex that it is not conducive to probability-based design optimization. This is so because the common method to evaluate probability is the Monte Carlo method which requires thousands of lifetime simulations to provide probability distributions. This paper presents a methodology that (1) replaces the implicit mechanistic model with a simple explicit model, and (2), transforms the dynamic, probabilistic, problem into a time invariant probability problem. Probabilities may be evaluated by any convenient method, although the first-order reliability method is particularly attractive because of its speed and accuracy. A part of the methodology invokes design of computer experiments and approximating functions. Training sets of the design variables are selected, a few computer experiments are run to produce a matrix of corresponding responses at discrete times, and then the matrix is replaced with a vector of so-called metamodels. Responses at an arbitrary design set and at any time are easily calculated and then used to formulate common, time-invariant, performance measures. Design variables are treated as random variables and limit-state functions are formed in standard normal probability space. Probability-based design is now straightforward and optimization determines the best set of distribution parameters. Systems reliability methods may be invoked for multiple competing performance measures. Further, singular value decomposition may be used to reduce greatly the number of metamodels needed by transforming the response matrix into two smaller matrices: One containing the design variable-specific information and the other the time-specific information. An error analysis is presented. A case study of a servo-control mechanism shows the new methodology provides controllable accuracy and a substantial time reduction when compared to the traditional mechanistic model with Monte Carlo sampling.
RELIABILITY AND SENSITIVITY ANALYSIS OF AN OPERATING SYSTEM WITH INSPECTION IN DIFFERENT WEATHER CONDITIONS
Authors: NAILWAL BEENA , SINGH S. B.
Published: May 2012

This paper deals with the reliability analysis of a system which consists of two subsystems namely main and standby with two weather conditions — normal and abnormal (turbulent). The subsystems are nonidentical and each has two modes — normal and total failure. The main subsystem is k-to-l-out-of-n and standby subsystem is k-out-of-n configurations. Single repairman is available for repair who plays the dual role of inspection and repair. Repairman inspects main subsystem and both the subsystems at its failure to see the feasibility of repair. If repair of the (sub) system is not feasible, it is replaced by new one. Inspection activities are stopped in abnormal weather conditions but system remains operative. Failure rates of both subsystems and the rate of change of weather conditions are constant, whereas the repair rates are general. With the help of Supplementary variable technique, Laplace transformations and copula methodology the transition state probabilities, asymptotic behavior and some characteristics such as reliability, availability, M.T.T.F., cost effectiveness and sensitivity of the system have been evaluated. At last some particular cases and numerical examples have been taken to describe the model.
ON AUTOMORPHISMS FIXING CERTAIN GROUPS
Authors: AZHDARI ZAHEDEH , AKHAVAN-MALAYERI MEHRI
Published: May 2012

Let G be a group and let M and N be two normal subgroups of G. Let [Formula: see text] be the set of all automorphisms of G which centralize G/M and N. In this paper, we find certain necessary and sufficient conditions on G such that [Formula: see text] be equal to Z( Inn (G)), Inn (G), C* or Aut c(G). We also characterize the subgroups of a finite p-group G for which the equality [Formula: see text] holds.
WEAK GORENSTEIN PROJECTIVE, INJECTIVE AND FLAT MODULES
Authors: GAO ZENGHUI
Published: May 2012

In this paper, weak Gorenstein projective, injective and flat modules are introduced and investigated. A left R-module M is called weak Gorenstein projective if there exists an exact sequence ⋯ → P1 → P0 → P0 → P1 → ⋯ of left R-modules such that: (1) all Pi and Pi are projective; and (2) M ≅ ker (P0 → P1). The weak Gorenstein injective and flat modules are defined similarly. Several well-known classes of rings are characterized in terms of weak Gorenstein projective, injective and flat modules. We also give a partial answer to Holm's question ([Question C, on p. 114 in Gorenstein projective, injective and flat modules, MSc thesis, Institute for Mathematical Sciences, University of Copenhagen (2000)]).
CONTINUED FRACTIONS WITH ODD PARTIAL QUOTIENTS
Authors: ZHABITSKAYA E. N.
Published: May 2012

Every Euclidean algorithm is associated with a kind of continued fraction representation of a number. The representation associated with "odd" Euclidean algorithm we will call "odd" continued fraction. We consider the limit distribution function F(x) for sequences of rationals with bounded sum of partial quotients for "odd" continued fractions. In this paper we prove certain properties of the function F(x). Particularly this function is singular and satisfies a number of functional equations. We also show that the value F(x) can be expressed in terms of partial quotients of the "odd" continued fraction representation of a number x.
ABEL ARITHMETIC FUNCTIONS IN FINITE CHARACTERISTIC
Authors: ADAM DAVID
Published: May 2012

We define Abel arithmetic functions in function fields with positive characteristic. We prove that any Abel arithmetic function with exponential type lesser than [Formula: see text] is a polynomial, the bound [Formula: see text] being optimal. This provides an analog of a Bertrandias' result. Some q-analogs are considered too.
p-ADIC INTERPOLATION OF METAPLECTIC FORMS OF COHOMOLOGICAL TYPE
Authors: HILL RICHARD , LOEFFLER DAVID
Published: May 2012

Let G be a reductive group over a number field k. It is shown how Emerton's methods may be applied to the problem of p-adically interpolating the metaplectic forms on G, i.e. the automorphic forms on metaplectic covers of G, as long as the metaplectic covers involved split at the infinite places of k.
A PROBLEM OF FOMENKO'S RELATED TO ARTIN'S CONJECTURE
Authors: FELIX ADAM TYLER , MURTY M. RAM
Published: May 2012

Let a be a natural number greater than 1. For each prime p, let ia(p) denote the index of the group generated by a in [Formula: see text]. Assuming the generalized Riemann hypothesis and Conjecture A of Hooley, Fomenko proved in 2004 that the average value of ia(p) is constant. We prove that the average value of ia(p) is constant without using Conjecture A of Hooley. More precisely, we show upon GRH that for any α with 0 ≤ α < 1, there is a positive constant cα > 0 such that [Formula: see text] where π(x) is the number of primes p ≤ x. We also study related questions.
A NOTE ON THE MEAN VALUE OF L-FUNCTIONS IN FUNCTION FIELDS
Authors: ANDRADE JULIO
Published: May 2012

An asymptotic formula for the sum ∑ L(1, χ) is established for a family of hyperelliptic curves of genus g over a fixed finite field 𝔽q as g → ∞ making use of the analog of the approximate functional equation for such L-functions. As a corollary, we obtain a formula for the average of the class number of the associated rings [Formula: see text].
ON THE SUM OF THE TWISTED EULER FUNCTION
Authors: KACZOROWSKI JERZY , WIERTELAK KAZIMIERZ
Published: May 2012

We study an asymptotic formula for the sum of values of the Euler φ-function twisted by a real Dirichlet character. The error term is split into the arithmetic and the analytic part. The former is studied with minimal use of analytic tools in contrast to the latter, where the analysis depends heavily on the distribution of the non-trivial zeros of the corresponding Dirichlet L-function. The results of the present paper are an extension of a recent work by the authors, where the case of the classical Euler φ-function has been studied. The present, more general situation invites new technical difficulties. Not all of them can be successfully overcome. For instance, satisfactory omega results for the analytic part are proved in the case of an even Dirichlet character only. Nevertheless, a method providing good omega estimates for the arithmetic part as well as for the complete error term is developed. Moreover, it is noted that the Riemann Hypothesis for the involved Dirichlet L-function is equivalent to a sufficiently sharp estimation of the analytic part. This shows in particular that the arithmetic part can be much larger than the corresponding analytic part.
INTEGRATION OF GENERAL AND PARTIAL EQUILIBRIUM AGRICULTURAL LAND-USE TRANSFORMATION FOR THE ANALYSIS OF CLIMATE CHANGE IN THE MEDITERRANEAN
Authors: PALATNIK RUSLANA R. , EBOLI FABIO , GHERMANDI ANDREA , KAN IDDO , RAPAPORT-ROM MICKEY , SHECHTER MORDECHAI
Published: May 2012

This study presents an internal modification of a dynamic computable general equilibrium model, ICES, employing inputs from a partial equilibrium model for the agricultural sector, VALUE. The aim is to quantify and analyze the medium-term socio-economic consequences of projected climate change. The methodology is innovative as it combines state-of-the-art knowledge from economic and biophysical sources and is demonstrated in application to two Mediterrenean countries: Israel and Italy. The information from the VALUE model was incorporated into the ICES economic model to improve the agricultural production structure. The new land allocation method takes into account the variation of substitutability across different types of land use. It captures agronomic features included in the VALUE model. This modification gives a better representation of heterogeneous information of land productivity to the economic framework. Climate impacts and policy evaluation with ICES are reinforced due to the more refined system of land allocation. This exercise is original in its ability to base the analysis on empirically estimated parameters rather than on assumptions, as in other studies of this kind. Notably, we suggest diverse land Constant Elasticity of Transformation (CET) frontiers for two main ecological regions in the Mediterranean basin for a more accurate representation of agronomic characteristics. Using the modified ICES model we evaluate climate change impact on agricultural production in the Mediterranean region.
ESTIMATING RICARDIAN MODELS WITH PANEL DATA
Authors: MASSETTI EMANUELE , MENDELSOHN ROBERT
Published: May 2012

Although the Ricardian model is a cross sectional method, there are advantages to estimating the model with additional years of data. For instance, with a panel, one can more easily separate events in a single year (e.g. weather and price shocks) from longer term phenomenon such as climate. Many early studies used repeated cross sections to study panel data but one can get consistently better performance from panel methods. In this paper, we rely on two panel methods to estimate the Ricardian function for the United States across time. The results suggest that moderate warming scenarios would benefit American agriculture as a whole but more extreme climate scenarios would be damaging.
GeV SCALE ASYMMETRIC DARK MATTER FROM MIRROR UNIVERSE: DIRECT DETECTION AND LHC SIGNATURES
Authors: CUI JIAN-WEI , HE HONG-JIAN , LÜ LAN-CHUN , YIN FU-RONG
Published: May 2012

Mirror universe is a fundamental way to restore parity symmetry in weak interactions. It naturally provides the lightest mirror nucleon as a unique GeV-scale asymmetric dark matter particle candidate. We conjecture that the mirror parity is respected by the fundamental interaction Lagrangian, and its possible soft breaking arises only from non-interaction terms in the gauge-singlet sector. We realize the spontaneous mirror parity violation by minimizing the vacuum Higgs potential, and derive the corresponding Higgs spectrum. We demonstrate that the common origin of CP violation in the visible and mirror neutrino seesaws can generate the right amount of matter and mirror dark matter via leptogenesis. We analyze the direct detections of GeV-scale mirror dark matter by TEXONO and CDEX experiments. We further study the predicted distinctive Higgs signatures at the LHC.
PROBING ISOSPIN-VIOLATING DARK MATTER
Authors: KUMAR JASON
Published: May 2012

We discuss experimental probes of isospin-violating dark matter (IVDM), including direct and indirect detection strategies. We point out the important role which IVDM plays in understanding recent data regarding low-mass dark matter, and describe strategies for finding evidence of IVDM at current and upcoming experiments.
CHALLENGES CONFRONTING SUPERLUMINAL NEUTRINO MODELS
Authors: EVSLIN JARAH
Published: May 2012

This talk opens the CosPA2011 session on OPERA's superluminal neutrino claim. I summarize relevant observations and constraints from OPERA, MINOS, ICARUS, KamLAND, IceCube and LEP as well as observations of SN1987A. I selectively review some models of neutrino superluminality which have been proposed since OPERA's announcement, focusing on a neutrino dark energy model. Powerful theoretical constraints on these models arise from Cohen-Glashow bremsstrahlung and from phase space requirements for the initial neutrino production. I discuss these constraints and how they might be evaded in models in which the maximum velocities of both neutrinos and charged leptons are equal but only superluminal inside of a dense medium.
CONSTRAINTS ON THE OPERA SUPERLUMINAL NEUTRINOS
Authors: YIN PENG-FEI , BI XIAO-JUN , YU ZHAO-HUAN , YUAN QIANG
Published: May 2012

The OPERA collaboration has recently reported the superluminal neutrinos with velocity of (vν - c)/c ~ 2.5 × 10-5. This result can be explained in the Lorentz invariance violation (LIV) models. The modified dispersion relation of neutrino lead to modified kinematics of the processes the neutrinos involved. For processes that neutrinos in the final states the processes are suppressed. We find to allow the neutrino production process π → μ + νμ, the neutrino energy should be less than about 5 GeV if taking a large LIV parameter ~ O(10-5) implied by OPERA data. For the processes that neutrinos in the initial states new processes that are forbidden in the LI scenario may open, such as the ν → ν + γ or ν → ν + e+ + e-, which lead neutrinos to lose energy quickly. As the atmospheric neutrino spectrum agrees well with expectation without LIV we find it can constrain the neutrino LIV parameter to ~ O(10-12), which is 7 orders smaller than the value measured at OPERA. We further propose to study the astrophysical neutrino spectra, which can constrain the neutrino LIV parameter down to O(10-15).
LEARNING ON THE THREE ROADS TO THE OPERA
Authors: AMELINO-CAMELIA GIOVANNI
Published: May 2012

Measurements of neutrino travel times reported last September by the OPERA collaboration have been analyzed franticly as possible evidence of superluminal propagation of a signal. Even in the likely scenario that the result ultimately does not stand up to further scrutiny, it will be worth taking notice of the few things that fundamental physics did learn in the process of studying the "OPERA anomaly".
DISPERSION RELATIONS EXPLAINING OPERA DATA FROM DEFORMED LORENTZ TRANSFORMATION
Authors: GUO GANG , HE XIAO-GANG
Published: May 2012

OPERA collaboration has reported evidence of superluminal phenomenon for neutrinos. One of the possible ways to explain the superluminality is to have Lorentz symmetry violated. It has been shown that dispersion relations put forwards has the problem of physics laws vary in different inertial frames leading to conflicting results on Cherenkov-like radiation, pion decay and high energy neutrino cosmic ray. For theories with deformed Lorentz symmetry, by modifying conservation laws corresponding to energy and momentum in the usual Lorentz invariant theory, it is possible to have superluminal effect and at the same time avoid to have conflicts encountered in Lorentz violating theories. We study dispersion relations from deformed Lorentz symmetry. We find that it is possible to have dispersion relations which can be consistent with data on neutrinos. We show that once the superluminality δv as a function of energy is known the corresponding dispersion relation in the deformed Lorentz symmetry can be determined.
Preparation of Ni Nanoparticles on Submicron-Sized Al2O3 Powdery Substrate by Polyhedral-Barrel-Sputtering Technique and Their Magnetic Properties
Authors: Akamaru Satoshi , Inoue Mitsuhiro , Honda Yuji , Taguchi Akira , Abe Takayuki
Published: May 2012

Ni nanoparticles were prepared on a submicron-sized Al2O3 powdery substrate by the polyhedral-barrel-sputtering technique and their microstructure and magnetic properties were investigated. By this technique, nanoparticles with an average diameter of 3.9–7.9 nm were prepared on the Al2O3 particles surface, and the size distribution of the nanoparticles was reproduced using a log-normal formula. The deposited Ni nanoparticles were composed of a NiO layer, which was formed by air oxidation, and a Ni core. The magnetization curves suggested that the all the prepared samples exhibited superparamagnetic behavior, which can be explained by considering the size distribution of the Ni nanoparticles. An exchange-bias effect, which arising from the core–shell structure, was also observed. From the saturated magnetic moments of the Ni core, the thickness of the surface layer was estimated to be 1.0–1.3 nm, which was comparable with that of passivated oxide layer of bulk Ni.
Rapid protein kinase D1 signaling promotes migration of intestinal epithelial cells
Authors: Young Steven H. , Rozengurt Nora , Sinnett-Smith James , Rozengurt Enrique
Published: May 2012

We have examined the role of protein kinase D1 (PKD1) signaling in intestinal epithelial cell migration. Wounding monolayer cultures of intestinal epithelial cell line IEC-18 or IEC-6 induced rapid PKD1 activation in the cells immediately adjacent to the wound edge, as judged by immunofluorescence microscopy with an antibody that detects the phosphorylated state of PKD1 at Ser916, an autophosphorylation site. An increase in PKD1 phosphorylation at Ser916 was evident as early as 45 s after wounding, reached a maximum after 3 min, and persisted for ≥15 min. PKD1 autophosphorylation at Ser916 was prevented by the PKD family inhibitors kb NB 142-70 and CRT0066101. A kb NB 142-70-sensitive increase in PKD autophosphorylation was also elicited by wounding IEC-6 cells. Using in vitro kinase assays after PKD1 immunoprecipitation, we corroborated that wounding IEC-18 cells induced rapid PKD1 catalytic activation. Further results indicate that PKD1 signaling is required to promote migration of intestinal epithelial cells into the denuded area of the wound. Specifically, treatment with kb NB 142-70 or small interfering RNAs targeting PKD1 markedly reduced wound-induced migration in IEC-18 cells. To test whether PKD1 promotes migration of intestinal epithelial cells in vivo, we used transgenic mice that express elevated PKD1 protein in the small intestinal epithelium. Enterocyte migration was markedly increased in the PKD1 transgenic mice. These results demonstrate that PKD1 activation is one of the early events initiated by wounding a monolayer of intestinal epithelial cells and indicate that PKD1 signaling promotes the migration of these cells in vitro and in vivo.
Serotonin availability in rat colon is reduced during a Western diet model of obesity
Authors: Bertrand R. L. , Senadheera S. , Tanoto A. , Tan K. L. , Howitt L. , Chen H. , Murphy T. V. , Sandow S. L. , Liu L. , Bertrand P. P.
Published: May 2012

Constipation and slowed transit are associated with diet-induced obesity, although the mechanisms by which this occurs are unclear. Enterochromaffin (EC) cells within the intestinal epithelium respond to mechanical stimulation with the release of serotonin [5-hydroxytryptamine (5-HT)], which promotes transit. Thus our aim was to characterize 5-HT availability in the rat colon of a physiologically relevant model of diet-induced obesity. EC cell numbers were determined immunohistochemically in chow-fed (CF) and Western diet-fed (WD) rats, while electrochemical methods were used to measure mechanically evoked (peak) and steady-state (SS) 5-HT levels. Fluoxetine was used to block the 5-HT reuptake transporter (SERT), and the levels of mRNA for tryptophan hydroxylase 1 and SERT were determined by quantitative PCR, and SERT protein was determined by Western blot. In WD rats, there was a significant decrease in the total number of EC cells per crypt (0.86 ± 0.06 and 0.71 ± 0.05 in CF and WD, respectively), which was supported by a reduction in the levels of 5-HT in WD rats (2.9 ± 1.0 and 10.5 ± 2.6 μM at SS and peak, respectively) compared with CF rats (7.3 ± 0.4 and 18.4 ± 3.4 μM at SS and peak, respectively). SERT-dependent uptake of 5-HT was unchanged, which was supported by a lack of change in SERT protein levels. In WD rats, there was no change in tryptophan hydroxylase 1 mRNA but an increase in SERT mRNA. In conclusion, our data show that foods typical of a WD are associated with decreased 5-HT availability in rat colon. Decreased 5-HT availability is driven primarily by a reduction in the numbers and/or 5-HT content of EC cells, which are likely to be associated with decreased intestinal motility in vivo.
Hyperhomocysteinemia decreases intestinal motility leading to constipation
Authors: Givvimani S. , Munjal C. , Narayanan N. , Aqil F. , Tyagi G. , Metreveli N. , Tyagi S. C.
Published: May 2012

Elevated levels of plasma homocysteine (Hcy) called hyperhomocysteinemia (HHcy) have been implicated in inflammation and remodeling in intestinal vasculature, and HHcy is also known to aggravate the pathogenesis of inflammatory bowel disease (IBD). Interestingly, colon is the pivotal site that regulates Hcy levels in the plasma. We hypothesize that HHcy decreases intestinal motility through matrix metalloproteinase-9 (MMP-9)-induced intestinal remodeling leading to constipation. To verify this hypothesis, we used C57BL/6J or wild-type (WT), cystathionine β-synthase (CBS+/−), MMP-9−/−, and MMP-9−/− + Hcy mice. Intestinal motility was assessed by barium meal studies and daily feces output. Plasma Hcy levels were measured by HPLC. Expression of ICAM-1, inducible nitric oxide synthase, MMP-9, and tissue inhibitors of MMPs was studied by Western blot and immunohistochemistry. Reactive oxygen species (ROS) including super oxide were measured by the Invitrogen molecular probe method. Tissue nitric oxide levels were assessed by a commercially available kit. Plasma Hcy levels in the treated MMP-9 group mice were comparable to CBS+/− mice. Barium meal studies suggest that intestinal motility is significantly decreased in CBS+/− mice compared with other groups. Fecal output-to-body weight ratio was significantly reduced in CBS+/− mice compared with other groups. There was significant upregulation of MMP-9, iNOS, and ICAM-1 expression in the colon from CBS+/− mice compared with WT mice. Levels of ROS, superoxide, and inducible nitric oxide were elevated in the CBS+/− mice compared with other groups. Results suggest that HHcy decreases intestinal motility due to MMP-9-induced intestinal remodeling leading to constipation.
Simultaneous detection of gastric acid and histamine release to unravel the regulation of acid secretion from the guinea pig stomach
Authors: Bitziou Eleni , Patel Bhavik Anil
Published: May 2012

Gastric acid secretion is regulated by three primary components that activate the parietal cell: histamine, gastrin, and acetylcholine (ACh). Although much is known about these regulatory components individually, little is known on the interplay of these multiple activators and the degree of regulation they pose on the gastric acid secretion mechanism. We utilized a novel dual-sensing approach, where an iridium oxide sensor was used to monitor pH and a boron-doped diamond electrode was used for the detection of histamine from in vitro guinea pig stomach mucosal sections. Under basal conditions, gastrin was shown to be the main regulatory component of the total acid secretion and directly activated the parietal cell rather than by mediating gastric acid secretion through the release of histamine from the enterochromaffin-like cell, although both pathways were active. Under stimulated conditions with ACh, the gastrin and histamine components of the total acid secretion were not altered compared with levels observed under basal conditions, suggestive that ACh had no direct effect on the enterochromaffin-like cell and G cell. These data identify a new unique approach to investigate the regulation pathways active during acid secretion and the degree that they are utilized to drive total gastric acid secretion. The findings of this study will enhance our understanding on how these signaling mechanisms vary under pathophysiology or therapeutic management.
Inert gas clearance from tissue by co-currently and counter-currently arranged microvessels
Authors: Lu Y. , Michel C. C. , Wang W.
Published: May 2012

To elucidate the clearance of dissolved inert gas from tissues, we have developed numerical models of gas transport in a cylindrical block of tissue supplied by one or two capillaries. With two capillaries, attention is given to the effects of co-current and counter-current flow on tissue gas clearance. Clearance by counter-current flow is compared with clearance by a single capillary or by two co-currently arranged capillaries. Effects of the blood velocity, solubility, and diffusivity of the gas in the tissue are investigated using parameters with physiological values. It is found that under the conditions investigated, almost identical clearances are achieved by a single capillary as by a co-current pair when the total flow per tissue volume in each unit is the same (i.e., flow velocity in the single capillary is twice that in each co-current vessel). For both co-current and counter-current arrangements, approximate linear relations exist between the tissue gas clearance rate and tissue blood perfusion rate. However, the counter-current arrangement of capillaries results in less-efficient clearance of the inert gas from tissues. Furthermore, this difference in efficiency increases at higher blood flow rates. At a given blood flow, the simple conduction-capacitance model, which has been used to estimate tissue blood perfusion rate from inert gas clearance, underestimates gas clearance rates predicted by the numerical models for single vessel or for two vessels with co-current flow. This difference is accounted for in discussion, which also considers the choice of parameters and possible effects of microvascular architecture on the interpretation of tissue inert gas clearance.
Muscle metabolic status and acid-base balance during 10-s work:5-s recovery intermittent and continuous exercise
Authors: Belfry Glen R. , Raymer Graydon H. , Marsh Gregory D. , Paterson Donald H. , Thompson R. Terry , Thomas Scott G.
Published: May 2012

Gastrocnemius muscle phosphocreatine ([PCr]) and hydrogen ion ([H+]) were measured using31P-magnetic resonance spectroscopy during repeated bouts of 10-s heavy-intensity (HI) exercise and 5-s rest compared with continuous (CONT) HI exercise. Recreationally active male subjects ( n = 7; 28 yr ± 9 yr) performed on separate occasions 12 min of isotonic plantar flexion (0.75 Hz) CONT and intermittent (INT; 10-s exercise, 5-s rest) exercise. The HI power output in both CONT and INT was set at 50% of the difference between the power output associated with the onset of intracellular acidosis and peak exercise determined from a prior incremental plantar flexion protocol. Intracellular concentrations of [PCr] and [H+] were calculated at 4 s and 9 s of the work period and at 4 s of the rest period in INT and during CONT exercise. [PCr] and [H+] (mean ± SE) were greater at 4 s of the rest periods vs. 9 s of exercise over the course of the INT exercise bout: [PCr] (20.7 mM ± 0.6 vs. 18.7 mM ± 0.5; P < 0.01); [H+] (370 nM ± 13.50 vs. 284 nM ± 13.6; P < 0.05). Average [H+] was similar for CONT vs. INT. We therefore suggest that there is a glycolytic contribution to ATP recovery during the very short rest period (<5 s) of INT and that the greater average power output of CONT did not manifest in greater [H+] and greater glycolytic contribution compared with INT exercise.
An amino acid mixture is essential to optimize insulin-stimulated glucose uptake and GLUT4 translocation in perfused rodent hindlimb muscle
Authors: Bernard Jeffrey R. , Liao Yi-Hung , Doerner Phillip G. , Ding Zhenping , Hsieh Ming , Wang Wanyi , Nelson Jeffrey L. , Ivy John L.
Published: May 2012

The purpose of this study was to investigate whether an amino acid mixture increases glucose uptake across perfused rodent hindlimb muscle in the presence and absence of a submaximal insulin concentration, and if the increase in glucose uptake is related to an increase in GLUT4 plasma membrane density. Sprague-Dawley rats were separated into one of four treatment groups: basal, amino acid mixture, submaximal insulin, or amino acid mixture with submaximal insulin. Glucose uptake was greater for both insulin-stimulated treatments compared with the non-insulin-stimulated treatment groups but amino acids only increased glucose uptake in the presence of insulin. Phosphatidylinositol 3-kinase (PI 3-kinase) activity was greater for both insulin-stimulated treatments with amino acids having no additional impact. Akt substrate of 160 kDa (AS160) phosphorylation, however, was increased by the amino acids in the presence of insulin, but not in the absence of insulin. AMPK was unaffected by insulin or amino acids. Plasma membrane GLUT4 protein concentration was greater in the rats treated with insulin compared with no insulin in the perfusate. In the presence of insulin, amino acids increased GLUT4 density in the plasma membrane but had no effect in the absence of insulin. AS160 phosphorylation and plasma membrane GLUT4 density accounted for 76% of the variability in muscle glucose uptake. Collectively, these findings suggest that the beneficial effects of an amino acid mixture on skeletal muscle glucose uptake, in the presence of a submaximal insulin concentration, are due to an increase in AS160 phosphorylation and plasma membrane-associated GLUT4, but independent of PI 3-kinase and AMPK activation.
Exercise modulation of the host-tumor interaction in an orthotopic model of murine prostate cancer
Authors: Jones Lee W. , Antonelli Jodi , Masko Elizabeth M. , Broadwater Gloria , Lascola Christopher D. , Fels Diane , Dewhirst Mark W. , Dyck Jason R. B. , Nagendran Jeevan , Flores Catherine T. , Betof Allison S. , Nelson Erik R. , Pollak Michael , Dash Rajesh C. , Young Martin E. , Freedland Stephen J.
Published: May 2012

The purpose of this study is to investigate the effects of exercise on cancer progression, metastasis, and underlying mechanisms in an orthotopic model of murine prostate cancer. C57BL/6 male mice (6–8 wk of age) were orthotopically injected with transgenic adenocarcinoma of mouse prostate C-1 cells (5 × 105) and randomly assigned to exercise ( n = 28) or a non-intervention control ( n = 31) groups. The exercise group was given voluntary access to a wheel 24 h/day for the duration of the study. Four mice per group were serially killed on days 14, 31, and 36; the remaining 38 mice (exercise, n = 18; control, n = 20) were killed on day 53. Before death, MRI was performed to assess tumor blood perfusion. Primary tumor growth rate was comparable between groups, but expression of prometastatic genes was significantly modulated in exercising animals with a shift toward reduced metastasis. Exercise was associated with increased activity of protein kinases within the MEK/MAPK and PI3K/mTOR signaling cascades with subsequent increased intratumoral protein levels of HIF-1α and VEGF. This was associated with improved tumor vascularization. Multiplex ELISAs revealed distinct reductions in plasma concentrations of several angiogenic cytokines in the exercise group, which was associated with increased expression of angiogenic and metabolic genes in the skeletal muscle. Exercise-induced stabilization of HIF-1α and subsequent upregulation of VEGF was associated with “productive” tumor vascularization with a shift toward suppressed metastasis in an orthotopic model of prostate cancer.
Estimating the Thermal Conductivities and Elastic Stiffness of Carbon Nanotubes as a Function of Tube Geometry
Authors: Zhang Z. H. , Yu N. , Chao W. H.
Published: May 2012

The thermal conductivities and elastic properties of carbon nanotubes (CNTs) are estimated by using the double‐inclusion model, which is based on rigorous elasticity approach. The model regards a CNT as one inclusion (the inner cylindrical void) embedded in the other (the outer coaxial single‐crystal graphite shell). The concept of homogenization is employed, and vital microstructural parameters, such as CNT diameter, length, and aspect ratio, are included in the present model. The relationship between microstructure and thermal conductivities and elastic stiffness of CNTs is quantitatively characterized. Our analytical results, benchmarked by experimental data, show that the thermal conductivities and elastic stiffness of CNTs are strongly dependent on the diameter of CNT with little dependence on the length of CNT.
Akt Promotes Post-Irradiation Survival of Human Tumor Cells through Initiation, Progression, and Termination of DNA-PKcs–Dependent DNA Double-Strand Break Repair
Authors: Toulany Mahmoud , Lee Kyung-Jong , Fattah Kazi R. , Lin Yu-Fen , Fehrenbacher Brigit , Schaller Martin , Chen Benjamin P. , Chen David J. , Rodemann H. Peter
Published: May 2012

Akt phosphorylation has previously been described to be involved in mediating DNA damage repair through the nonhomologous end-joining (NHEJ) repair pathway. Yet the mechanism how Akt stimulates DNA-protein kinase catalytic subunit (DNA-PKcs)-dependent DNA double-strand break (DNA-DSB) repair has not been described so far. In the present study, we investigated the mechanism by which Akt can interact with DNA-PKcs and promote its function during the NHEJ repair process. The results obtained indicate a prominent role of Akt, especially Akt1 in the regulation of NHEJ mechanism for DNA-DSB repair. As shown by pull-down assay of DNA-PKcs, Akt1 through its C-terminal domain interacts with DNA-PKcs. After exposure of cells to ionizing radiation (IR), Akt1 and DNA-PKcs form a functional complex in a first initiating step of DNA-DSB repair. Thereafter, Akt plays a pivotal role in the recruitment of AKT1/DNA-PKcs complex to DNA duplex ends marked by Ku dimers. Moreover, in the formed complex, Akt1 promotes DNA-PKcs kinase activity, which is the necessary step for progression of DNA-DSB repair. Akt1-dependent DNA-PKcs kinase activity stimulates autophosphorylation of DNA-PKcs at S2056 that is needed for efficient DNA-DSB repair and the release of DNA-PKcs from the damage site. Thus, targeting of Akt results in radiosensitization of DNA-PKcs and Ku80 expressing, but not of cells deficient for, either of these proteins. The data showed indicate for the first time that Akt through an immediate complex formation with DNA-PKcs can stimulate the accumulation of DNA-PKcs at DNA-DSBs and promote DNA-PKcs activity for efficient NHEJ DNA-DSB repair. Mol Cancer Res; 10(7); 945–57. ©2012 AACR.
Mechanisms of Cell Death in Heart Disease
Authors: Konstantinidis Klitos , Whelan Russell S. , Kitsis Richard N.
Published: May 2012

The major cardiac syndromes, myocardial infarction and heart failure, are responsible for a large portion of deaths worldwide. Genetic and pharmacological manipulations indicate that cell death is an important component in the pathogenesis of both diseases. Cells die primarily by apoptosis or necrosis, and autophagy has been associated with cell death. Apoptosis has long been recognized as a highly regulated process. Recent data indicate that a significant subset of necrotic deaths is also programmed. In the review, we discuss the molecular mechanisms that underlie these forms of cell death and their interconnections. The possibility is raised that small molecules aimed at inhibiting cell death may provide novel therapies for these common and lethal heart syndromes.
Prevalence of Kawasaki Disease in Young Adults With Suspected Myocardial Ischemia
Authors: Daniels Lori B. , Tjajadi Matthew S. , Walford Hannah H. , Jimenez-Fernandez Susan , Trofimenko Vera , Fick Daryl B. , Phan Hoang-Anh L. , Linz Peter E. , Nayak Keshav , Kahn Andrew M. , Burns Jane C. , Gordon John B.
Published: May 2012

Background—

Up to 25% of patients with untreated Kawasaki disease (KD) and 5% of those treated with intravenous immunoglobulin will develop coronary artery aneurysms. Persistent aneurysms may remain silent until later in life when myocardial ischemia can occur. We sought to determine the prevalence of coronary artery aneurysms suggesting a history of KD among young adults undergoing coronary angiography for evaluation of possible myocardial ischemia.

Methods and Results—

We reviewed the medical histories and coronary angiograms of all adults <40 years of age who underwent coronary angiography for evaluation of suspected myocardial ischemia at 4 San Diego hospitals from 2005 to 2009 (n=261). History of KD-compatible illness and cardiac risk factors were obtained by medical record review. Angiograms were independently reviewed for the presence, size, and location of aneurysms and coronary artery disease by 2 cardiologists blinded to the history. Patients were evaluated for number of risk factors, angiographic appearance of their coronary arteries, and known history of KD. Of the 261 young adults who underwent angiography, 16 had coronary aneurysms. After all clinical criteria were assessed, 5.0% had aneurysms definitely (n=4) or presumed (n=9) secondary to KD as the cause of their coronary disease.

Conclusions—

Coronary sequelae of KD are present in 5% of young adults evaluated by angiography for myocardial ischemia. Cardiologists should be aware of this special subset of patients who may benefit from medical and invasive management strategies that differ from the strategies used to treat atherosclerotic coronary artery disease.
Effective Schools: Teacher Hiring, Assignment, Development, and Retention
Authors: Loeb Susanna , Kalogrides Demetra , Béteille Tara
Published: May 2012

The literature on effective schools emphasizes the importance of a quality teaching force in improving educational outcomes for students. In this article we use value-added methods to examine the relationship between a school's effectiveness and the recruitment, assignment, development, and retention of its teachers. Our results reveal four key findings. First, we find that more effective schools are able to attract and hire more effective teachers from other schools when vacancies arise. Second, more effective schools assign novice teachers to students in a more equitable fashion. Third, teachers who work in schools that were more effective at raising achievement in a prior period improve more rapidly in a subsequent period than do those in less effective schools. Finally, we find that more effective schools are better able to retain higher-quality teachers. The results point to the importance of personnel and, perhaps, school personnel practices for improving student outcomes.
The Leading Pattern of Intraseasonal and Interannual Indian Ocean Precipitation Variability and Its Relationship with Asian Circulation during the Boreal Cold Season
Authors: Hoell Andrew , Barlow Mathew , Saini Roop
Published: May 2012

The leading pattern of precipitation for the Indian Ocean, one of the most intense areas of rainfall on the globe, is calculated for November–April 1979–2008. The associated regional circulation and thermodynamic forcing of precipitation over Asia are examined at both intraseasonal and interannual time scales. The leading pattern is determined using both empirical orthogonal function analysis of monthly precipitation data and a closely related index of daily outgoing longwave radiation filtered into intraseasonal (33–105 days) and interannual (greater than 105 days) components.

The leading pattern has a maximum in the tropical eastern Indian Ocean, and is closely associated with the Madden–Julian oscillation at intraseasonal time scales and related to the El Niño–Southern Oscillation at interannual time scales. Both time scales are associated with baroclinic Gill–Matsuno-like circulation responses extending over southern Asia, but the interannual component also has a strong equivalent barotropic circulation. Thermodynamically, both time scales are associated with cold temperature advection and subsidence over southwest Asia, with advection of the mean temperature by the anomalous wind more important at lower and midlevels and advection of the anomalous temperature by the mean wind more important at upper levels.

For individual months, the intraseasonal variability can overwhelm the interannual variability. Enhanced Indian Ocean convection persisted for almost the entire 2007/08 season in association with severe drought over southwest Asia, but a strong intraseasonal signal in January 2008 reversed the pattern, resulting in damaging floods in the midst of drought.
Australian Practice Standards nine years on: Are they useful?
Authors: Laragy Carmel , Bland Robert , Giles Roslyn , Scott Virginia
Published: May 2012

Nine years after their introduction, the Australian Social Work Practice Standards are reviewed against the five purposes of codes of practice proposed by Banks (2006). The review concludes that the Standards contributed to heightened professional identity and accountability by defining the national education curriculum and by providing a mechanism for accountability. Their utility for service users is still to be determined.
The class impact of post disaster restoration policies: The example of Ilia, Greece and the need for a politics of disaster
Authors: Pentaraki Maria
Published: May 2012

This article presents research findings from selected rural communities that were struck in 2007 by one of the largest fires in history in Greece. The restoration policies implemented resulted in a class-differentiated recovery process. The article examines this development in the context of neoliberal policies and argues that political context should be a locus of intervention.
Children of War and Peace
Authors: Sagi-Schwartz Abraham
Published: May 2012

Political conflicts and intractable wars can be conceived as disasters of human activities and they affect the entire life of children and their families. An ecological-transactional perspective of human development is adopted in order to identify multilevel developmental and contextual trajectories that might facilitate or impede the willingness and readiness of people to engage openly and flexibly in conflict-resolution paradigms. It is proposed that building early trustful relationships at the interpersonal level is likely to enhance one’s willingness and ability to explore the other side’s goals in the conflict, and ultimately to consider reconciliation. At the same time, the absence of such trustful relationships is likely to induce more rigid and one-sided approaches in adulthood. Toward that end, the Palestinian–Israeli conflict serves as the main context of analysis.