bluuebunny/crossref_metadata_2025 huggingface dataset:
Gatekeepers and the Gateway – a Mixed-Methods Inquiry into Practitioners' Referral Behaviour to the Gateway Clinic
Authors: Unwin Jason , Peters David
Published: April 2009

Background

The Gateway Clinic is a specialist NHS service in South London providing acupuncture and Chinese medicine. The clinic receives a diverse range of referrals from an expanding population of local general practitioners (GPs).

Objectives

This study explores the referral behaviour of GPs and other primary care users of the Gateway Clinic.

Methods

A pragmatic mixed-methods approach was used, combining mapping of GPs’ usage of the Gateway as taken from the clinic's database between the years 2000 and 2005, a questionnaire survey of the referring primary care practitioners in 2005, and data, including a thematic analysis of the interview transcripts from semi-structured interviews of a purposive sample of those GPs who refer.

Results

Doctors in the community refer a wide range of health problems to the Gateway Clinic. The most common referrals were musculoskeletal conditions (38–44%), general and unspecified conditions (11–14%), blood and immune system conditions (6–12%), psychological conditions (8–13%), neurological conditions (6–9%), gynaecological conditions (5–6%) and digestive conditions (5–6%). The health problems referred by local healthcare practitioners correlate strongly with the patient profile seen in private acupuncture practice. Between 2000 and 2005 numbers of healthcare practitioners increased by 218% resulting in a 300% increase in patient referrals made to the clinic; the mean frequency of referral per practitioner increased by 71%. Analysis of the qualitative data suggests that positive clinical experience encourages GPs to increase the range of conditions they refer leading to the development of informal referral guidelines.

Conclusion

The Gateway Clinic has become an increasingly popular referral resource. The influences that drive referral to the clinic are multiple and follow “tacit guidelines”. GPs select patients on the basis of their individual clinical experience, informed by positive patient feedback and often only after more conventional medical treatment options have been exhausted.
Pilot Study to Assess the Credibility of Acupuncture in Acute Exacerbations of Chronic Obstructive Pulmonary Disease
Authors: Whale Claudia A , MacLaran Sarah J A , Whale Christopher I , Barnett Mandy
Published: April 2009

Background

Exacerbation of chronic obstructive pulmonary disease (COPD) is a common reason for hospital admission, and adjunctive non-pharmacological treatments would be welcomed. A pilot study was undertaken to assess the feasibility of conducting a study of acupuncture during an acute exacerbation of COPD. We also examined the credibility of a sham device in this setting and assessed the effect of acupuncture on breathlessness and anxiety.

Methods

A prospective, randomised, patient- and assessor-blinded, sham controlled study was conducted on three consecutive days in a district general hospital. Credibility of both acupuncture and the Park sham device were assessed using the Borkovec and Nau questionnaire. Dyspnoea was measured on the modified Borg score and a 10 cm visual analogue scale, while anxiety was measured on a 10 cm visual analogue scale.

Results

11 patients were recruited and nine completed the study. There were no adverse events with either intervention. Acupuncture was well tolerated and credibility scores were similar before and after real and sham acupuncture. Symptoms improved after both treatments, with no significant difference between groups.

Conclusion

In this pilot study acupuncture was well tolerated by subjects experiencing an acute exacerbation of COPD. Acupuncture treatment and the Park sham device were both credible. Although recruitment was slow, a further trial with a larger sample size is feasible and recommended.
Triglycerides and total serum cholesterol in rotator cuff tears: do they matter?
Authors: Longo U G , Franceschi F , Spiezia F , Forriol F , Maffulli N , Denaro V
Published: April 2009

Objective

In this study, the serum triglycerides and total serum cholesterol levels in patients with rotator cuff tear were determined.

Design

Frequency-matched case-control study.

Setting

University teaching hospital.

Participants

240 individuals who were operated on at our institution were included in the study. 120 patients (45 men and 75 women; mean age 64.86 years, range 40 to 83 years) who underwent arthroscopic repair of a rotator cuff tear were included in group 1. 120 patients (45 men and 75 women; mean age 63.91 years, range 38 to 78 years) who underwent arthroscopic meniscectomy for a meniscal tear and had no evidence of shoulder pathology were included in group 2 (control group). These patients were frequency-matched by age (within 3 years) and sex with patients of group 1.

Main outcome measures

Measurement of serum triglyceride and total cholesterol concentrations.

Results

When comparing the two groups, there was no difference either in serum triglyceride concentration or total serum cholesterol concentration.

Conclusions

There appears to be no association between serum triglyceride concentration and total serum cholesterol concentration in rotator cuff tears.
VACUUM POLARIZATION BY FERMIONIC FIELDS IN HIGHER DIMENSIONAL COSMIC STRING SPACE-TIME
Authors: SPINELLY J. , DE MELLO E. R. BEZERRA
Published: April 2009

In this paper we investigate vacuum polarization effects associated with charged massive quantum fermionic fields in a six-dimensional cosmic string space-times considering the presence of a magnetic flux running along its core. We have shown that for specific values of the parameters which codify the presence of the cosmic string, and the fractional part of the ratio of the magnetic flux by the quantum one, a closed expression for the respective Green function is obtained. Adopting this result, we explicitly calculate the renormalized vacuum expectation value of the energy-momentum tensor, [Formula: see text], and analyse this result in some limiting cases.
BLACK HOLES AND BLACK STRING-LIKE SOLUTIONS IN CODIMENSION-2 BRANEWORLDS
Authors: PAPANTONOPOULOS ELEFTHERIOS
Published: April 2009

We discuss black hole solutions with a Gauss-Bonnet term in the bulk and an induced gravity term on a thin brane of codimension-2. We show that these black holes can be localized on the brane, and they can be extended further into the bulk by a warp function. These solutions have regular horizons and no other curvature singularities appear apart from the string-like ones. The projection of the Gauss-Bonnet term on the brane imposes a constraint relation which dictates the form of matter on the brane and in the bulk.
EMBEDDING VERSUS IMMERSION IN GENERAL RELATIVITY
Authors: MONTE EDMUNDO M.
Published: April 2009

We briefly discuss the concepts of immersion and embedding of space-times in higher-dimensional spaces. We revisit the classical work by Kasner in which he constructs a model of immersion of the Schwarzschild exterior solution into a six-dimensional pseudo-Euclidean manifold. We show that, from a physical point of view, this model is not entirely satisfactory, since the causal structure of the immersed space-time is not preserved by the immersion.
ON WEYL COSMOLOGY IN FIVE DIMENSIONS AND THE COSMOLOGICAL CONSTANT
Authors: AGUILAR JOSE EDGAR MADRIZ , ROMERO CARLOS
Published: April 2009

In this talk notes we expose the possibility to induce the cosmological constant from extra dimensions from a geometrical framework where our four-dimensional Riemannian spacetime is embedded into a five-dimensional Weyl integrable space. In particular following the approach of the induced matter theory (IMT) we show that when we go down from five to four dimensions we may recover the induced energy momentum tensor of the IMT plus a cosmological constant term that is determined by the presence of the Weyl scalar field on the bulk.
NONLINEAR RESONANCE IN BRANEWORLD COSMOLOGIES
Authors: MAIER R. , DAMIÃO SOARES I. , TONINI E. V.
Published: April 2009

The phase space dynamics of preinflationary closed Friedmann-Robertson-Walker (FRW) models is examined in a string-inspired bulk-brane scenario. Friedmann equations on the brane contain correction terms arising from the brane-bulk interaction that implement nonsingular metastable bounces in the early evolution of the universe. The matter content of the model is a massive inflaton field plus dust and/or radiation. In narrow windows of the parameter space, labeled by an integer n ≥ 2, nonlinear resonance phenomena destroy KAM tori that trap the inflaton, leading to a graceful entrance to inflation. As a consequence nonlinear resonance imposes constraints on the physical parameters, and in the initial configurations of the models so that inflation may be realized.
STABILITY OF AdS BLACK STRINGS
Authors: DELSATE TÉRENCE
Published: April 2009

We review the recent developements in the stability problem and phase diagram for asymptotically locally AdS black strings. First, we quickly review the case of locally flat black string before turning to the case of locally AdS spacetimes.
ON A RESULT CONCERNING THE BEHAVIOR OF A RELATIVISTIC QUANTUM SYSTEM IN THE COSMIC STRING SPACETIME
Authors: BEZERRA V. B. , DE A. MARQUES GEUSA
Published: April 2009

We consider the problem of a relativistic electron in the presence of a Coulomb potential and a magnetic field in the background spacetime corresponding to a cosmic string. We find the solution of the corresponding Dirac equation and determine the energy spectrum of the particle.
QUANTUM THERMODYNAMICS OF MASSLESS BOSONS IN UNIVERSES WITH VII0 × VIII ISOMETRIES
Authors: DARIESCU MARINA-AURA , DARIESCU CIPRIAN , PÎRGHIE ANA-CAMELIA
Published: April 2009

In the spacetime described by a metric with g44 = - cosh 2(αz), we are pointing out some unusual (pathological) features as for example a genuine temporal imprisonment of null geodesics. For the massless bosons evolving in such an Universe, we solve the Gordon equation and derive the characteristic function and the main thermodynamic quantities.
INSTABILITIES OF NAKED SINGULARITIES AND BLACK HOLE INTERIORS IN GENERAL RELATIVITY
Authors: DOTTI GUSTAVO , GLEISER REINALDO J. , PULLIN JORGE , RANEA-SANDOVAL IGNACIO F. , VUCETICH HÉCTOR
Published: April 2009

Metrics representing black holes in General Relativity may exhibit naked singularities for certain values of their parameters. This is the case for super-extremal (J2 > M > 0) Kerr and super-extremal (|Q| > M > 0) Reissner-Nördstrom spacetimes, and also for the negative mass Schwarzschild spacetime. We review our recent work where we show that these nakedly singular spacetimes are unstable under linear gravitational perturbations, a result that supports the cosmic censorship conjecture, and also that the inner stationary region beyond the inner horizon of a Kerr black hole (J2 < M) is linearly unstable.
RELATIVISTIC DYNAMICS WITH COSMOLOGICAL CONSTANT: CIRCULAR GEODESIC MOTION OF TEST PARTICLES
Authors: SLANÝ PETR , KOVÁŘ JIŘÍ , STUCHLÍK ZDENĚK
Published: April 2009

We present results of our recent studies concerning effects of Λ > 0 in astrophysically motivated problems. Here we summarize properties of circular geodesic motion of test particles in the equatorial plane of Kerr-de Sitter black-hole and naked-singularity spacetimes. Along with the standard analysis of geodesic equations of the ordinary geometry, we introduce alternative inertial forces formalism defined within the General Theory of Relativity in the framework of optical reference geometry.
SUPERHEAVY PARTICLES AS DARK MATTER AND THEIR ROLE IN CREATION OF VISIBLE MATTER IN ACTIVE GALACTIC NUCLEI AND THE EARLY UNIVERSE
Authors: GRIB A. A. , PAVLOV YU. V.
Published: April 2009

The hypothesis that dark matter consists of superheavy neutral particles with the mass of the Grand Unification scale is considered. The hypothesis that dark matter is converted into visible one in active galactic nuclei is investigated. If active galactic nuclei are rotating black holes then due to Penrose process superheavy particles can decay on nonstable particles with larger mass the decay of which on quarks and leptons leads to events in cosmic rays observed by the Auger group. Similar processes of decay of superheavy particles of dark matter into visible matter occurred in the early Universe. Numerical estimates of the processes in active galactic nuclei and in the early Universe are given.
SCALAR-TENSOR COSMOLOGIES: GENERAL RELATIVITY AS A FIXED POINT OF THE JORDAN FRAME SCALAR FIELD
Authors: KUUSK PIRET , JÄRV LAUR , SAAL MARGUS
Published: April 2009

We study the evolution of homogeneous and isotropic, flat cosmological models within the general scalar-tensor theory of gravity with arbitrary coupling function and potential and scrutinize its limit to general relativity. Using the methods of dynamical systems for the decoupled equation of the Jordan frame scalar field we find the fixed points of flows in two cases: potential domination and matter domination. We present the conditions on the mathematical form of the coupling function and potential which determine the nature of the fixed points (attractor or other). There are two types of fixed points, both are characterized by cosmological evolution mimicking general relativity, but only one of the types is compatible with the Solar System PPN constraints.
A SIMPLE QUINTESSENTIAL INFLATION MODEL
Authors: BENTO M. C. , FELIPE R. GONZÁLEZ , SANTOS N. M. C.
Published: April 2009

A simple model of quintessential inflation with the modified exponential potential e-αϕ[A + (ϕ-ϕ0)2] is analyzed in the braneworld context. Considering reheating via instant preheating, the evolution of the scalar field from inflation to the present epoch is consistent with the observational constraints in a wide region of the parameter space.
ACCELERATED EXPANSION OF THE UNIVERSE THROUGH INTERACTIONS IN THE COSMIC SUBSTRATUM
Authors: ZIMDAHL WINFRIED
Published: April 2009

Various homogeneous and isotropic cosmological models which describe the present stage of accelerated expansion of the Universe, like the ΛCDM model or (generalized) Chaplygin gas models, can be seen as specific realizations of a holographic dark energy cosmology if an interaction within the cosmic substratum is admitted. The corresponding interaction strength parameter determines the cosmological constant. The transition from decelerated to accelerated expansion arises as a pure interaction phenomenon. Different from the "standard" ΛCDM and Chaplygin gas models, the interaction based approach is characterized by non-adiabatic pressure perturbations.
ON THE COSMOLOGICAL EFFECTS OF THE WEYSSENHOFF SPINNING FLUID IN THE EINSTEIN-CARTAN FRAMEWORK
Authors: DE BERREDO-PEIXOTO GUILHERME , DE FREITAS EMANUEL ANTONIO
Published: April 2009

The effects of non-Riemannian structures in Cosmology have been studied long ago and are still a relevant subject of investigation. In the seventies, it was discovered that singularity avoidance and early accelerated expansion can be induced by torsion in the Einstein-Cartan theory. In this framework, torsion is not dynamical and is completely expressed by means of the spin sources. Thus, in order to study the effects of torsion in the Einstein-Cartan theory, one has to introduce matter with spin. In principle, this can be done in several ways. In this work we consider the cosmological evolution of the universe in the presence of a constant isotropic and homogeneous axial current and the Weyssenhoff spinning fluid. We analyse possible solutions of this model, with and without the spinning fluid.
DENSITY PERTURBATIONS AND THE CHAPLYGIN GAS
Authors: SILVA E COSTA SANDRO
Published: April 2009

One approach in modern cosmology consists in supposing that dark matter and dark energy are different manifestations of a single 'quartessential' fluid. Following such idea, this work presents a summary of some studies of the evolution of density perturbations in a flat cosmological model with a modified Chaplygin gas acting as a single component. Our goal is to obtain properties of the model which can be used to distinguish it from another cosmological models which have the same solutions for the general evolution of the scale factor of the universe, even without the construction of the power spectrum. Both our analytical and numerical results clearly indicate as one interesting feature of the model the presence of peaks in the evolution of the density constrast.
GEOMETRY OF SPACETIME AND FINSLER GEOMETRY
Authors: TAVAKOL REZA
Published: April 2009

A central assumption in general relativity is that the underlying geometry of spacetime is pseudo-Riemannian. Given the recent attempts at generalizations of general relativity, motivated both by theoretical and observational considerations, an important question is whether the spacetime geometry can also be made more general and yet still remain compatible with observations? Here I briefly summarize some earlier results which demonstrate that there are special classes of Finsler geometry, which is a natural metrical generalization of the Riemannian geometry, that are strictly compatible with the observations regarding the motion of idealised test particles and light rays. I also briefly summarize some recent attempts at employing Finsler geometries motivated by more recent developments such as those in String theory, whereby Lorentz invariance is partially broken.
A TYPE OF BORN-INFELD REGULAR GRAVITY AND ITS COSMOLOGICAL CONSEQUENCES
Authors: FIORINI FRANCO , FERRARO RAFAEL
Published: April 2009

Born-Infeld deformation strategy to smooth theories having divergent solutions is applied to the teleparallel equivalent of General Relativity. The equivalence between teleparallelism and General Relativity is exploited to obtain a deformed theory of gravity based on second order differential equations, since teleparallel Lagrangian is built just from first derivatives of the vierbein. We show that Born-Infeld teleparallelism cures the initial singularity in a spatially flat FRW universe; moreover, it provides a natural inflationary stage without resorting to an inflaton field. The Born-Infeld parameter λ bounds the dynamics of Hubble parameter H(t) and establishes a maximum attainable spacetime curvature.
A DYNAMICAL SYSTEM APPROACH FOR THE BONDI PROBLEM
Authors: DE OLIVEIRA H. P. , RODRIGUES E. L.
Published: April 2009

We present the first numerical code based on the Galerkin method to integrate the field equations of the Bondi problem. The Galerkin method is a spectral method whose main feature is to provide high accuracy with moderate computational effort. Several numerical tests were performed to verify the issues of convergence, stability and accuracy with promising results. This code opens up several possibilities of applications in more general scenarios for studying the evolution of spacetimes with gravitational waves.
DECOHERENCE AND RECOHERENCE IN MODEL QUANTUM SYSTEMS
Authors: HSIANG JEN-TSUNG , FORD L. H.
Published: April 2009

We discuss the various manifestations of quantum decoherence in the forms of dephasing, entanglement with the environment, and revelation of "which-path" information. As a specific example, we consider an electron interference experiment. The coupling of the coherent electrons to the quantized electromagnetic field illustrates all of these versions of decoherence. This decoherence has two equivalent interpretations, in terms of photon emission or in terms of Aharonov-Bohm phase fluctuations. We consider the case when the coherent electrons are coupled to photons in a squeezed vacuum state. The time-averaged result is increased decoherence. However, if only electrons which are emitted during selected periods are counted, the decoherence can be suppressed below the level for the photon vacuum. This is the phenomenon of recoherence. This effect is closely related to the quantum violations of the weak energy condition, and is restricted by similar inequalities. We give some estimates of the magnitude of the recoherence effect and discuss prospects for observing it in an electron interferometry experiment.
SYMMETRY REDUCTIONS AND EXACT SOLUTIONS FOR NONLINEAR DIFFUSION EQUATIONS
Authors: BORDAG LJUDMILA A.
Published: April 2009

The symmetry properties of nonlinear diffusion equations are studied using a Lie group analysis. Reductions and families of exact solutions are found for some of these equations.
BEYOND PROXIMITY FORCE APPROXIMATION IN THE CASIMIR EFFECT
Authors: BORDAG M. , NIKOLAEV V.
Published: April 2009

We compare the analytical and numerical results for the Casimir force for the configuration of a plane and a cylinder in front of a plane. While for Dirichlet boundary conditions on both, plane and sphere or cylinder, agreement is found, for Neumann boundary conditions on either the plane or one of the two, cylinder or sphere, disagreement is found. This holds, for a sphere, also for different boundary conditions on the interacting surfaces. From recent, new numerical results for the cylinder, a general appearance of logarithmic contributions beyond PFA can be predicted.
MEASUREMENT OF THE CASIMIR FORCE USING A MICROMECHANICAL TORSIONAL OSCILLATOR: ELECTROSTATIC CALIBRATION
Authors: DECCA RICARDO S. , LÓPEZ DANIEL
Published: April 2009

Experimental procedures associated with the electrostatic calibration of a microelectromechanical torsional oscillator are reported. These calibrations are required for the precision measurements of the Casimir force between a Au -coated sapphire sphere and a Au -coated polysilicon plate. It is shown that the electrostatic force between the surfaces is made zero by the application of a potential difference Vo between the sphere and the plate. Vo is found to be independent of position and separation within the experimental error.
PROBLEMS IN THE LIFSHITZ THEORY OF ATOM-WALL INTERACTION
Authors: KLIMCHITSKAYA G. L. , BLAGOV E. V. , MOSTEPANENKO V. M.
Published: April 2009

Problems in the Lifshitz theory of atom-wall interaction arise when the dc conductivity of dielectric wall is included into the model of the dielectric response. We review the low-temperature behavior of the free energy and entropy of dispersion interaction for both dielectric and metallic walls. Consistency of the obtained results with thermodynamics and experimental data is analyzed. Recent attempts to include the screening effects and diffusion currents into the Lifshitz theory are considered. It is shown that this leads to the violation of the Nernst heat theorem for wide classes of wall materials. The physical reasons for the emergence of thermodynamic and experimental inconsistencies are elucidated.
THEORY OF THE CASIMIR EFFECT IN ONE-DIMENSIONAL PERIODIC DIELECTRIC SYSTEMS
Authors: LAMBRECHT ASTRID , MARACHEVSKY VALERY N.
Published: April 2009

We derive an exact theory of the Casimir interaction between two arbitrary dielectric gratings with coinciding periods d. We then express the Casimir energy for two dielectric gratings or periodic dielectrics with coinciding periods in terms of Rayleigh coefficients.
DISPERSION FORCES AND DUALITY
Authors: BUHMANN STEFAN YOSHI , SCHEEL STEFAN , SAFARI HASSAN , WELSCH DIRK-GUNNAR
Published: April 2009

We formulate a symmetry principle on the basis of the duality of electric and magnetic fields and apply it to dispersion forces. Within the context of macroscopic quantum electrodynamics, we rigorously establish duality invariance for the free electromagnetic field in the presence of causal magnetoelectrics. Dispersion forces are given in terms of the Green tensor for the electromagnetic field and the atomic response functions. After discussing the behavior of the Green tensor under a duality transformation, we are able to show that Casimir forces on bodies in free space as well as local-field corrected Casimir–Polder and van der Waals forces are duality invariant.
GRAVITATION AS A CASIMIR EFFECT
Authors: SERNELIUS BO E.
Published: April 2009

We describe how dispersion forces between two atoms in ordinary electromagnetism come about and how they may be derived. Then we introduce hypothetical particles interacting with a harmonic oscillator interaction potential. We demonstrate that in a system with this type of interacting particles the retarded dispersion interaction between composite particles varies as 1/r, i.e. just like the gravitational potential does. This demonstrates that gravitation can be a Casimir effect.
CASIMIR EFFECT IN TOROIDALLY COMPACTIFIED DE SITTER SPACETIME
Authors: SAHARIAN A. A.
Published: April 2009

Vacuum energy density and stresses are investigated for a scalar field with general curvature coupling parameter in (D + 1)-dimensional de Sitter spacetime with an arbitrary number of toroidally compactified spatial dimensions. The corresponding expectation values are presented in the form of the sum of the vacuum expectation values in uncompactified dS spacetime and the part induced by the non-trivial topology. In the early stages of the cosmological evolution the topological parts dominate. In this limit the behavior of the Casimir densities does not depend on the curvature coupling parameter and coincides with that for a conformally coupled massless field. At late stages of the cosmological expansion the expectation values are dominated by the part corresponding to uncompactified dS spacetime. The vanishing of the topological parts is monotonic or oscillatory in dependence of the mass and the curvature coupling parameter of the field.
REPULSIVE GRAVITY AND THE CASIMIR EFFECT ON SPHERICAL UNIVERSES
Authors: HERDEIRO CARLOS A. R. , RIBEIRO RAQUEL H. , SAMPAIO MARCO
Published: April 2009

We describe the Casimir effect of a free scalar field coupled to gravity on an n + 1-dimensional Einstein Static Universe (ESU), with arbitrary low energy effective operators (up to mass dimension n + 1). We discuss the variation of the effect from attractive to repulsive and some possible physical consequences.
A TRACE FORMULA FOR A FAMILY OF JACOBI OPERATORS
Authors: AGNEW ALFONSO F. , BOURGET ALAIN
Published: April 2009

In this paper, we compute the leading term in the asymptotic expansion of the trace of a family of Jacobi matrices as their order gets arbitrarily large. We then apply this formula to compute the density of states of the zeros of a class of polynomials associated with the Heun differential equation.
EXISTENCE RESULTS FOR A CLASS OF NON-UNIFORMLY ELLIPTIC EQUATIONS OF p-LAPLACIAN TYPE
Authors: NGÔ QUỐC-ANH
Published: April 2009

In this paper, we establish the existence of non-trivial weak solutions in [Formula: see text], 1 < p < ∞, to a class of non-uniformly elliptic equations of the form [Formula: see text] in a bounded domain Ω of ℝN. Here a satisfies [Formula: see text] for all ξ ∈ ℝN, a.e. x ∈ Ω, [Formula: see text], [Formula: see text], h0(x) ≧ 0, h1(x) ≧ 1 for a.e. x in Ω.
DIFFERENTIAL EQUATIONS WITH COEFFICIENTS OF SLOW GROWTH IN THE UNIT DISC
Authors: XIAO LIPENG , CHEN ZONGXUAN
Published: April 2009

In this paper, the growth of solutions and the number of fast-growing linearly independent solutions of certain linear differential equations with coefficients of slow growth in the unit disc are investigated. The results we obtain are a generalization of a recent result due to Korhonen and Rättyä.
AN SI EPIDEMIC MODEL WITH NONLINEAR INFECTION RATE AND STAGE STRUCTURE
Authors: ZOU WEI , XIE JIEHUA
Published: April 2009

In this paper, we study an SI epidemic model with nonlinear infection rate and stage structure. The conditions for the existence of various equilibriums are established. The threshold that the epidemic will die out or become local epidemic is found.
SIV EPIDEMIC MODELS WITH AGE OF INFECTION
Authors: YANG JUN-YUAN , ZHANG FENG-QIN , WANG XIAO-YAN
Published: April 2009

accination is a very important strategy for the elimination of infectious diseases. An SIV epidemic model with age of infection and vaccination has been formulated in this paper. Using the theory of differential and integral equation, we show that the infection-free equilibrium is locally asymptotically stable if the reproductive number R0 < 1, and the endemic equilibrium is locally asymptotically stable if R0 > 1.
EXTENDING FEYNMAN'S FORMALISMS FOR MODELING HUMAN JOINT ACTION COORDINATION
Authors: IVANCEVIC VLADIMIR G. , AIDMAN EUGENE V. , YEN LEONG
Published: April 2009

The recently developed Life-Space-Foam approach to goal-directed human action deals with individual actor dynamics. This paper applies the model to characterize the dynamics of co-action by two or more actors. This dynamics is modelled by (i) a two-term joint action (including cognitive/motivatonal potential and kinetic energy), and (ii) its associated adaptive path integral, representing an infinite-dimensional neural network. Its feedback adaptation loop has been derived from Bernstein's concepts of sensory corrections loop in human motor control and Brooks' subsumption architectures in robotics. Potential applications of the proposed model in human-robot interaction research are discussed.
INTELLIGENT SOFTWARE ANALYZER DESIGN FOR PARAMETERS EVALUATION OF TERNARY HEAVY METAL IONS REMOVAL BY IMMOBILIZED FUNGAL BIOMASS
Authors: VASSILEVA SVETLA , TSEKOVA KOLISHKA , CHRISTOVA DARINKA , TODOROVA DESSISLAVA
Published: April 2009

In this paper the fuzzy logic method improved by adaptive learning of a fuzzy inference system, based on anfis, was used to demonstrate a software analyzer design for parameters evaluation of ternary heavy metal ions removal. The studied process was conducted to investigate metal binding ability of the novel hybrid hydrogel, obtained by entrapping Penicillium cyclopium biomass into chemically cross-linked poly (vinyl alcohol) (PVA) network toward Cu 2+, Co 2+ and Fe 3+ from ternary aqueous solution. The performance of the biosorbent was evaluated by determining the values of heavy metal uptake and heavy metal removal efficiency in the ternary metal mixture. The innovative immobilization technology developed provides an attractive strategy for the developing high-affinity biosorption system for the treatment of wastewater containing heavy metals in low concentration. The obtained results of both — the studied process and software analyzer design and implementation are illustrated and discussed.
ANALYSIS OF STABILITY AND PERSISTENCE IN A RATIO-DEPENDENT PREDATOR-PREY RESOURCE MODEL
Authors: FREEDMAN H. I. , AGARWAL MANJU , DEVI SAPNA
Published: April 2009

This paper deals with a predator-prey model having ratio-dependent functional response with an additional predator resource. By means of a transformation of variables, we transform the model into a dynamical system in such a way that there is a one-to-one correspondence between the positive values of the original model and positive values of the transformed model, so that the results which are true for the transformed model are also valid for the original model. Mathematical analyses of the model equations with regard to the nature of equilibria, boundedness of solutions, and persistence are carried out. We obtain conditions which influence the boundedness and persistence of all the populations. From numerical calculations, we show that in the absence of any resource, the predator population density decreases and is less than the prey population density, but in the presence of a resource, the predator population density becomes enhanced and dominates the prey population density.
THE ROLE OF DENDRITIC CELLS AND OTHER IMMUNE MECHANISMS DURING HUMAN INFECTION WITHMYCOBACTERIUM TUBERCULOSIS
Authors: MAGOMBEDZE GESHAM , GARIRA WINSTON , MWENJE EDDIE
Published: April 2009

Human immune response mechanisms are crucial in the control of Mycobacterium tuberculosis (Mtb) infection. Understanding the human immune mechanisms and Mtb dynamics will assist in understanding the occurrence of different clinical outcomes experienced by individuals infected with Mtb. This work elaborates the role of dendritic cells (DCs) and other immune mechanisms in Mtb infection. We develop a model to predict disease progression scenarios, that is latency or active disease. Model analysis shows that occurrence of active disease is much attributed to the Mtb pathogen's ability to persist outside the intracellular environment and that strong immune response results in latent TB while relatively weak immune response result in active tuberculosis (TB). Our numerical results show that DCs recruitment, antigen (Ag) uptake and maturation affect the priming of the immune response and T cells levels at the site of infection. This study shows the crucial link between the innate immune mechanisms and the adaptive immune mechanisms. It also suggests directions for further basic studies and potential new treatment strategies.
Modulation of Cx46 hemichannels by nitric oxide
Authors: Retamal Mauricio A. , Yin ShengYong , Altenberg Guillermo A. , Reuss Luis
Published: April 2009

Gap-junction hemichannels are composed of six protein subunits (connexins). Undocked hemichannels contribute to physiological autocrine/paracrine cell signaling, including release of signaling molecules, cell-volume regulation, and glucose uptake. In addition, hemichannels may be pathologically activated by dephosphorylation and cell-membrane depolarization. Such hemichannel opening may induce and/or accelerate cell death. It has been suggested that connexin43 (Cx43) hemichannels are sensitive to redox potential changes and that one or more intracellular cysteines is/are important for this process. Cx46 is expressed in the lens, and its dysfunction induces cataract formation. It contains six cysteines in the extracellular loops, one in the fourth transmembrane helix, and two in the COOH-terminal domain. The latter may be susceptible to oxidation by nitric oxide (NO), which could be involved in cataract formation through cysteine S-nitrosylation. Here we report studies of the effects of the NO donor S-nitrosoglutathione (GSNO) on the electrical properties and fluorescent-dye permeability of wild-type Cx46 and mutant hemichannels expressed in Xenopus laevis oocytes. GSNO enhanced hemichannel voltage sensitivity, increased tail-current amplitude, and changed activation and closing kinetics in Cx46 and Cx46-CT43 (Cx46 mutant in which the COOH terminus was replaced with that of Cx43), but not in Cx46-C3A (Cx46 in which the intracellular and transmembrane helix 4 cysteines were mutated to alanine). We conclude that Cx46 hemichannels are sensitive to NO and that the NO effects are mediated by modification of one or more intracellular cysteines. However, it is unlikely that NO induces cataract formation due to the hemichannel activation, because at normal resting potential, NO had no major effects on Cx46 hemichannel permeability.
Facilitated maturation of Ca2+ handling properties of human embryonic stem cell-derived cardiomyocytes by calsequestrin expression
Authors: Liu Jing , Lieu Deborah K. , Siu Chung Wah , Fu Ji-Dong , Tse Hung-Fat , Li Ronald A.
Published: April 2009

Cardiomyocytes (CMs) are nonregenerative. Self-renewable pluripotent human embryonic stem cells (hESCs) can differentiate into CMs for cell-based therapies. We recently reported that Ca2+ handling, crucial to excitation-contraction coupling of hESC-derived CMs (hESC-CMs), is functional but immature. Such immature properties as smaller cytosolic Ca2+ transient amplitudes, slower kinetics, and reduced Ca2+ content of sarcoplasmic reticulum (SR) can be attributed to the differential developmental expression profiles of specific Ca2+ handling and regulatory proteins in hESC-CMs and their adult counterparts. In particular, calsequestrin (CSQ), the most abundant, high-capacity but low-affinity, Ca2+-binding protein in the SR that is anchored to the ryanodine receptor, is robustly expressed in adult CMs but completely absent in hESC-CMs. Here we hypothesized that gene transfer of CSQ in hESC-CMs suffices to induce functional improvement of SR. Transduction of hESC-CMs by the recombinant adenovirus Ad-CMV-CSQ-IRES-GFP (Ad-CSQ) significantly increased the transient amplitude, upstroke velocity, and transient decay compared with the control Ad-CMV-GFP (Ad-GFP) and Ad-CMV-CSQΔ-IRES-GFP (Ad-CSQΔ, which mediated the expression of a nonfunctional, truncated version of CSQ) groups. Ad-CSQ increased the SR Ca2+ content but did not alter L-type Ca2+ current. Pharmacologically, untransduced wild-type, Ad-GFP-, Ad-CSQΔ-, and Ad-CSQ-transduced hESC-CMs behaved similarly. Whereas ryanodine significantly reduced the Ca2+ transient amplitude and slowed the upstroke, thapsigargin slowed the decay. Neither triadin nor junctin was affected. We conclude that CSQ expression in hESC-CMs facilitates Ca2+ handling maturation. Our results shed insights into the suitability of hESC-CMs for therapies and as certain heart disease models for drug screening.
Inflammasome-mediated regulation of hepatic stellate cells
Authors: Watanabe Azuma , Sohail Muhammad Adnan , Gomes Dawidson Assis , Hashmi Ardeshir , Nagata Jun , Sutterwala Fayyaz Shiraz , Mahmood Shamail , Jhandier Muhammad Nauman , Shi Yan , Flavell Richard Anthony , Mehal Wajahat Zafar
Published: April 2009

The inflammasome is a cytoplasmic multiprotein complex that has recently been identified in immune cells as an important sensor of signals released by cellular injury and death. Analogous to immune cells, hepatic stellate cells (HSC) also respond to cellular injury and death. Our aim was to establish whether inflammasome components were present in HSC and could regulate HSC functionality. Monosodium urate (MSU) crystals (100 μg/ml) were used to experimentally induce inflammasome activation in LX-2 and primary mouse HSC. Twenty-four hours later primary mouse HSC were stained with α-smooth muscle actin and visualized by confocal microscopy, and TGF-β and collagen1 mRNA expression was quantified. LX-2 cells were further cultured with or without MSU crystals for 24 h in a transwell chemotaxis assay with PDGF as the chemoattractant. We also examined inhibition of calcium (Ca2+) signaling in LX-2 cells treated with or without MSU crystals using caged inositol 1,4,5-triphosphate (IP3). Finally, we confirmed an important role of the inflammasome in experimental liver fibrosis by the injection of carbon tetrachloride (CCl4) or thioacetamide (TAA) in wild-type mice and mice lacking components of the inflammasome. Components of the inflammasome are expressed in LX-2 cells and primary HSC. MSU crystals induced upregulation of TGF-β and collagen1 mRNA and actin reorganization in HSCs from wild-type mice but not mice lacking inflammasome components. MSU crystals inhibited the release of Ca2+ via IP3 in LX-2 cells and also inhibited PDGF-induced chemotaxis. Mice lacking the inflammasome-sensing and adaptor molecules, NLRP3 and apoptosis-associated speck-like protein containing CARD, had reduced CCl4 and TAA-induced liver fibrosis. We concluded that inflammasome components are present in HSC, can regulate a variety of HSC functions, and are required for the development of liver fibrosis.
Renal and cardiovascular characterization of COX-2 knockdown mice
Authors: Seta Francesca , Chung Andrew D. , Turner Patricia V. , Mewburn Jeffrey D. , Yu Ying , Funk Colin D.
Published: April 2009

Selective cyclooxygenase-2 (COX-2) inhibitors (coxibs) increase the incidence of cardiovascular and cerebrovascular events. Complete disruption of the murine gene encoding COX-2 ( Ptgs2) leads to renal developmental problems, as well as female reproductive anomalies and patent ductus arteriosus of variable penetrance in newborns, thus rendering this genetic approach difficult to compare with coxib administration. Here, we created hypomorphic Ptgs2 (COX-2Neo/Neo) mice in which COX-2 expression is suppressed to an extent similar to that achieved with coxibs, but not eliminated, in an attempt to circumvent these difficulties. In LPS-challenged macrophages and cytokine-stimulated endothelial cells obtained from COX-2Neo/Neomice, COX-2 expression was reduced 70–90%, and these mice developed a mild renal phenotype compared with COX-2 mice possessing an active site mutation (COX-2Y385F/Y385F), with minimal signs of renal dysfunction as measured by FITC-inulin clearance and blood urea nitrogen. These COX-2 knockdown mice displayed an increased propensity for thrombogenesis compared with their wild-type (COX-2+/+) littermates observed by intravital microscopy in cremaster muscle arterioles upon ferric chloride challenge. Measurement of urinary prostanoid metabolites indicated that COX-2Neo/Neomice produced 50% less prostacyclin but similar levels of PGE2and thromboxane compared with COX-2+/+mice in the absence of any blood pressure and ex vivo platelet aggregation abnormalities. COX-2Neo/Neomice, therefore, provide a genetic surrogate of coxib therapy with disrupted prostacyclin biosynthesis that predisposes to induced arterial thrombosis.
RhCG is the major putative ammonia transporter expressed in the human kidney, and RhBG is not expressed at detectable levels
Authors: Brown Alice C. N. , Hallouane Dalila , Mawby William J. , Karet Fiona E. , Saleem Moin A. , Howie Alexander J. , Toye Ashley M.
Published: April 2009

Rhesus glycoprotein homologs RhAG, RhBG, and RhCG comprise a recently identified branch of the Mep/Amt ammonia transporter family. Animal studies have shown that RhBG and RhCG are present in the kidney distal tubules. Studies in mouse and rat tissue suggest a basolateral localization for RhBG in cells of the distal tubules including the α-intercalated cells (α-IC), but no localization of RhBG has been reported in human tissue. To date RhCG localization has been described as exclusively apical plasma membrane in mouse and rat kidney, or apical and basolateral in humans, and some mouse and rat tissue studies. We raised novel antibodies to RhBG and RhCG to examine their localization in the human kidney. Madin-Darby canine kidney (MDCKI) cell lines stably expressing human green fluorescent protein-tagged RhBG or RhCG and human tissue lysates were used to demonstrate the specificity of these antibodies for detecting RhBG and RhCG. Using immunoperoxidase staining and antigen liberation techniques, both apical and basolateral RhCG localization was observed in the majority of the cells of the distal convoluted tubule and IC of the connecting tubule and collecting duct. Confocal microscopic imaging of normal human kidney cryosections showed that RhCG staining was predominantly localized to the apical membrane in these cells with some basolateral and intracellular staining evident. A proportion of RhCG staining labeled kAE1-positive cells, confirming that RhCG is localized to the α-IC cells. Surprisingly, no RhBG protein was detectable in the human kidney by Western blot analysis of tissue lysates, or by immunohistochemistry or confocal microscopy of tissue sections. The same antibodies, however, could detect RhBG in rat tissue. We conclude that under normal conditions, RhCG is the major putative ammonia transporter expressed in the human kidney and RhBG is not expressed at detectable levels.
Podocyte-specific expression of organic cation transporter PMAT: implication in puromycin aminonucleoside nephrotoxicity
Authors: Xia Li , Zhou Mingyan , Kalhorn Thomas F. , Ho Horace T. B. , Wang Joanne
Published: April 2009

Plasma membrane monoamine transporter (PMAT) is a novel polyspecific organic cation transporter that transports organic cations and the purine nucleoside, adenosine. PMAT is expressed in the kidney, but the specific localization and function of this transporter in renal cells are unclear. In this study, we developed a polyclonal antibody toward a 14-amino acid sequence in the last intracellular loop of PMAT and determined the precise cellular localization of PMAT in human and rat kidneys. Surprisingly, we found that the PMAT protein was predominantly expressed in the glomerulus with minimal expression in tubular cells. Within the glomerulus, dual-color immunofluorescence labeling showed that the PMAT protein was specifically localized to the visceral glomerular epithelial cells, i.e., podocytes. There was no significant PMAT immunoreactivity in mesangial or glomerular endothelial cells. We further showed that puromycin aminonucleoside (PAN), a classic podocyte toxin that induces massive proteinuria and severe glomerulopathy, is transported by PMAT. Expression of PMAT in Madin-Darby canine kidney cells significantly increased cell sensitivity to PAN. Decynium 22, a potent PMAT inhibitor, abolished PAN toxicity in PMAT-expressing cells. Together, our data suggest that PMAT is specifically expressed in podocytes and may play an important role in PAN-induced kidney injury.
N-methyl-d-aspartate receptors are expressed in rat parathyroid gland and regulate PTH secretion
Authors: Parisi Eva , Almadén Yolanda , Ibarz Mercé , Panizo Sara , Cardús Anna , Rodriguez Mariano , Fernandez Elvira , Valdivielso Jose M.
Published: April 2009

N-methyl-d-aspartate receptors (NMDAR) are tetrameric amino acid receptors which act as membrane calcium channels. The presence of the receptor has been detected in the principal organs responsible for calcium homeostasis (kidney and bone), pointing to a possible role in mineral metabolism. In the present work, the presence of the receptor was determined in normal parathyroid glands (PTG) by real-time PCR, immunoprecipitation, and immunohistrochemistry. Healthy animals showed a decrease in blood parathyroid hormone (PTH) levels 15 min after the treatment with NMDA. This effect was also observed in animals with high levels of PTH-induced EDTA injection, but not in uremic animals with secondary hyperparathyroidism (2HPT). Normal rat PTG incubated in media with low calcium concentration (0.8 mM CaCl2) showed a decrease in PTH release when NMDA was added to the media. This effect of NMDA was abolished when glands were coincubated with MK801 (a pharmacological blocker of the NMDA channel) or PD98059 (an inhibitor of the ERK-MAPK pathway). Glands obtained from animals with 2HPT showed no effect of NMDA in the in vitro release of PTH, together with a decrease in the expression of NMDAR1. In conclusion, NMDA receptor is present in PTG and is involved in the regulation of the PTH release. The mechanism by which NMDAR exerts its function is through the activation of the MAPK cascade. In uremic 2HPT animals the receptor expression is downregulated and the treatment with NMDA does not affect PTH secretion.
Organic cation transporters OCT1, 2, and 3 mediate high-affinity transport of the mutagenic vital dye ethidium in the kidney proximal tubule
Authors: Lee Wing-Kee , Reichold Markus , Edemir Bayram , Ciarimboli Giuliano , Warth Richard , Koepsell Hermann , Thévenod Frank
Published: April 2009

The positively charged fluorescent dyes ethidium (Et+) and propidium (Pr2+) are widely used as DNA and necrosis markers. Et+is cytotoxic and mutagenic. The polyspecific organic cation transporters OCT1 (SLC22A1), OCT2 (SLC22A2), and OCT3 (SLC22A3) mediate electrogenic facilitated diffusion of small (≤500 Da) organic cations with broad specificities. In humans, OCT2 mediates basolateral uptake by kidney proximal tubules (PT), whereas in rodents OCT1/2 are involved. In mouse kidney, perfused Et+accumulated predominantly in the S2/S3 segments of the PT, but not Pr2+. In cells stably overexpressing human OCTs (hOCTs), Et+uptake was observed with Kmvalues of 0.8 ± 0.2 μM (hOCT1), 1.7 ± 0.5 μM (hOCT2), and 2.0 ± 0.5 μM (hOCT3), whereas Pr2+was not transported. Accumulation of Et+was inhibited by OCT substrates quinine, 3-methyl-4-phenylpyridinium (MPP+), cimetidine, and tetraethylammonium (TEA+). For hOCT1 and hOCT2, the IC50values for MPP+, TEA+, and cimetidine were higher than for inhibition of previously tested transported substrates. For hOCT2, the inhibition of Et+uptake by MPP+and cimetidine was shown to be competitive. Et+also inhibited transport of 0.1 μM [3H]MPP+by all hOCT isoforms with IC50values between 0.4 and 1.3 μM, and the inhibition of hOCT1-mediated uptake of MPP+by Et+was competitive. In Oct1/2−/−mice, Et+uptake in the PT was almost abolished. The data demonstrate that Et+is taken up avidly by the PT, which is mediated by OCT1 and/or OCT2. Considering the high affinity of OCTs for Et+and their strong expression in various organs, strict safety guidelines for Et+handling should be reinforced.