bluuebunny/crossref_metadata_2025 huggingface dataset:
STOCHASTIC FLUCTUATIONS IN THE PRIMEVAL PLASMA OF THE UNIVERSE
Authors: FANG LI-ZHI , HUANG ZHENG , WU XIANG-PING
Published: October 2004

Before recombination of the universe the cosmic “fluid” consisting of primeval plasma and radiation cannot be perfect, but necessarily possesses nonvanishing dissipations. The subhorizon evolution of density perturbations in the radiation-plasma system must be described by stochastic kinetic theories. Both the dissipation and stochastic fluctuation in the coupled radiation-plasma system are caused by the incoherent electron-photon scattering. Using the Boltzmann equation with a Langevin-like term describing the stochastic force, we investigate the influence of this incoherent scattering on the evolution of acoustic oscillations in the radiation-plasma system. The stochastic fluctuation per collision time on average is small. Nevertheless, it cumulatively leads to a significant Brownian drifting of the phase of the acoustic oscillations. The coherence of the oscillations cannot be maintained during their evolution by the recombination. As a consequence, the linear-theory-predicted fine structures in the angular power spectrum of the anisotropies of cosmic microwave radiation, such as the Doppler peaks, are most likely erased by the stochastic fluctuations.
EFFECTS OF NEUTRINO OSCILLATION ON THE SUPERNOVA RELIC NEUTRINO BACKGROUND
Authors: TOTANI TOMONORI , SATO KATSUHIKO
Published: October 2004

We investigate to what extent the oscillation or conversion of neutrinos enhances the expected event rate of the supernova relic neutrino background (SRN) at the SuperKamiokande detector (SK). The SRN [Formula: see text] can be almost completely exchanged with vμ-like neutrinos by the MSW oscillation under the inverse mass hierarchy with Δm2~ 10−8–105[eV2], or by the magnetic moment of Majorana neutrinos with μv≳10−12μB and Δm2~10−4–10° [eV2]. In the standard calculation of the SRN flux, the event rate of the SRN [Formula: see text] at the SK in the observable energy range of 15–40 MeV can be enhanced from 1.2 yr−1 to 2.4 yr−1 if all [Formula: see text] are exchanged with vμ-like neutrinos. The enhancement is prominent especially in the high energy range (≳ 25 MeV). In the astrophysically optimistic calculation, the event rate becomes as high as 9.4 yr−1. Because the theoretical upper bound of the SRN events without oscillation is about 5 yr−1 taking into account the various astrophysical uncertainties, we might have to resort to the neutrino oscillation if more than 5 events in a year, as well as a significantly harder spectrum, were observed in the SK.
DE SITTER-SCHWARZSCHILD BLACK HOLE: ITS PARTICLELIKE CORE AND THERMODYNAMICAL PROPERTIES
Authors: DYMNIKOVA I.G.
Published: October 2004

We analyze the globally regular solution of the Einstein equations describing a black hole whose singularity is replaced by the de Sitter core. The de Sitter—Schwarzschild black hole (SSBH) has two horizons. Inside of it there exists a particlelike structure hidden under the external horizon. The critical value of mass parameter M cr1 exists corresponding to the degenerate horizon. It represents the lower limit for a black-hole mass. Below M cr1 there is no black hole, and the de Sitter-Schwarzschild solution describes a recovered particlelike structure. We calculate the Hawking temperature of SSBH and show that specific heat is broken and changes its sign at the value of mass M cr 2>M cr 1 which means that a second-order phase transition occurs at that point. We show that the Hawking temperature drops to zero when a mass approaches the lower limit M cr1 .
INFLATION FROM SUPERSTRINGS
Authors: MACORRA A. DE LA , LOLA S.
Published: October 2004

We investigate the possibility of obtaining inflationary solutions from a low energy Lagrangian coming from superstrings. In any viable scheme, the dilaton and the moduli fields have to be stabilized and before this happens, no other field may be used as the inflaton. We show that in a class of models where supersymmetry breaking occurs via gaugino condensation, the dilaton and the moduli fields can be stabilised in a way that enables the use of chiral matter fields in order to obtain enough e-folds of inflation. In a superstring model this is not straightforward, because the form of the Kähler potential is restricted and certain relations between the chiral and moduli fields lead in general to a steep potential. We identify a subclass of Kähler potentials and a certain region of the parameter space of the chiral and moduli fields that may lead to enough inflation. The conditions that we have derived for inflation due to chiral fields are generic and apply also in schemes where the dilaton and moduli fields may be frozen in alternative ways. Demanding that the potential terms associated with the chiral fields do not spoil the dilaton and moduli minimization under the specific scheme that we use to freeze the dilaton, leads to severe constraints on the magnitude of the density fluctuations.
SUPERGRAVITY AND CANONICAL QUANTIZATION
Authors: D’EATH P.D.
Published: October 2004

The quantization of supergravity is discussed using a canonical approach, in which one solves the supersymmetry constraints SAΨ=0, [Formula: see text] where Ψ is a physical state. It appears, using an approach which involves auxiliary fields, that the amplitude to go from initial to final gravitational data (with zero gravitino data) is Ψ=exp(−IB/ħ), where IB is the classical Einstein-Hilbert action. This then suggests that fermionic amplitudes (including gravitino boundary data) may also be finite.
POLYMER GEOMETRY AT PLANCK SCALE AND QUANTUM EINSTEIN EQUATIONS
Authors: ASHTEKAR ABHAY
Published: October 2004

Over the last two years, the canonical approach to quantum gravity based on connections and triads has been put on a firm mathematical footing through the development and application of a new functional calculus on the space of gauge equivalent connections. This calculus does not use any background fields (such as a metric) and thus well-suited to a fully non-perturbative treatment of quantum gravity. Using this framework, quantum geometry is examined. Fundamental excitations turn out to be one-dimensional, rather like polymers. Geometrical observables such as areas of surfaces and volumes of regions are purely discrete spectra. Continuum picture arises only upon coarse graining of suitable semi-classical states. Next, regulated quantum diffeomorphism constraints can be imposed in an anomaly-free fashion and the space of solutions can be given a natural Hilbert space structure. Progress has also been made on the quantum Hamiltonian constraint in a number of directions. In particular, there is a recent approach based on a generalized .Wick transformation which maps solutions to the Euclidean quantum constraints to those of the Lorentzian theory. These developments are summarized. Emphasis is on conveying the underlying ideas and overall pictures rather than technical details.
QUANTUM BLACK HOLE MODEL AND HAWKING’S RADIATION
Authors: BEREZIN VICTOR
Published: October 2004

The black hole model with a self-gravitating charged spherical symmetric dust thin shell as a source is considered. The Schroedinger-type equation for such a model is derived. This equation appeared to be a finite differences equation. A theory of such an equation is developed and general solution is found and investigated in details. The discrete spectrum of the bound state energy levels is obtained. All the eigenvalues appeared to be infinitely degenerate. The ground state wave functions are evaluated explicitly. The quantum black hole states are selected and investigated. It is shown that the obtained black hole mass spectrum is compatible with the existence of Hawking’s radiation in the limit of low temperatures both for large and nearly extreme Reissner-Nordstrom black holes. The above mentioned infinite degeneracy of the mass (energy) eigenvalues may appeared helpful in resolving the well known information paradox in the black hole physics.
ON BLACK HOLE CREATION IN PLANCKIAN ENERGY SCATTERING
Authors: AREF’EVA I. YA. , VOLOVICH I.V. , VISWANATHAN K.S.
Published: October 2004

In a series of papers Amati, Ciafaloni and Veneziano and ’t Hooft conjectured that black holes occur in the collision of two light particles at planckian energies. In this talk based on [10] we discuss a possible scenario for such a process by using the Chandrasekhar-Ferrari-Xanthopoulos duality between the Kerr black hole solution and colliding plane gravitational waves.
ELECTRIC/MAGNETIC DUALITY AND ITS STRINGY ORIGINS
Authors: DUFF M.J.
Published: October 2004

We review electric/magnetic duality in N=4 (and certain N=2) globally supersymmetric gauge theories and show how this duality, which relates strong to weak coupling, follows as a consequence of a string/string duality. Black holes, eleven dimensions and supermembranes also have a part to play in the big picture.
NONLINEAR REALISATIONS AND EMBEDDINGS OF QUANTUM ALGEBRAS
Authors: STELLE K.S.
Published: October 2004

A review is given of BRST mechanisms through which theories carrying realisations of nonlinear gauge-algebra representations may also be viewed as realizing embeddings into larger gauge algebras. This process generalizes the familiar non-linear realisations of spontaneously-broken Lie-algebra gauge symmetries to ssupersymmetric and higher-spin chiral quantum gravity models.
HIGHER-SPIN GAUGE THEORIES IN FOUR, THREE AND TWO DIMENSIONS
Authors: VASILIEV M.A.
Published: October 2004

We review the theory of higher-spin gauge fields in four and three space-time dimensions and present some new results on higher-spin gauge interactions of matter fields in two dimensions.
SINGULARITIES IN INFLATIONARY COSMOLOGY: A REVIEW
Authors: BORDE ARVIND , VILENKIN ALEXANDER
Published: October 2004

We review here some recent results that show that inflationary cosmological models must contain initial singularities. We also present a new singularity theorem. The question of the initial singularity re-emerges in inflationary cosmology because inflation is known to be generically futureeternal, It is natural to ask, therefore, if inflationary models can be continued into the infinite past in a non-singular way. The results that we discuss show that the answer to the question is “no.” This means that we cannot use inflation as a way of avoiding the question of the birth of the Universe. We also argue that our new theorem suggests — in a sense that we explain in the paper — that the Universe cannot be infinitely old.
QUANTUM ORIGIN OF THE ENERGY SCALE OF INFLATION: NO-BOUNDARY VS TUNNELLING WAVEFUNCTIONS
Authors: BARVINSKY A.O. , KAMENSHCHIK A. YU.
Published: October 2004

Quantum origin of the early inflationary Universe from the no-boundary and tunnelling quantum states is considered in the one-loop approximation of quantum cosmology. A universal effective action algorithm for the distribution function of chaotic inflationary cosmologies is derived for both of these states. The energy scale of inflation is calculated by finding a sharp probability peak in this distribution function for a tunnelling model driven by the inflaton field with large negative constant ξ of nonminimal interaction. The sub-Planckian parameters of this peak (the mean value of the corresponding Hubble constant H≃10−5mp, its quantum width ΔH/H≃10−5 and the number of inflationary e-foldings N≃60) are found to be in good correspondence with the observational status of inflation theory, provided the coupling constants of the theory are constrained by a condition which is likely to be enforced by the (quasi) supersymmetric nature of the sub-Planckian particle physics model.
ON THE EXTENSION OF THE PERIODIC SYSTEM INTO THE SECTORS OF STRANGENESS AND ANTIMATTER
Authors: GREINER WALTER
Published: October 2004

After a brief review of the standard extension of the periodic system into the islands of superheavy elements and out to the proton and neutron drip lines, we shall discuss its continuation into the sectors of antimatter and strangeness. A tremendously rich scenario of new nuclear structure emerges, with new magic numbers in the strangeness domain and new forms of nuclear clusters combined of p, n, Λ, Σ, Ξ, etc. The production mechanisms for these objects and for antinuclei rest in high energetic heavy-ion collisions. Various possibilities are discussed, some of them quantitatively.
VACUUM STRUCTURE IN QCD WITH QUARK AND GLUON CONDENSATES
Authors: MISHRA A. , MISHRA H. , SHEEL VARUN , MISRA S.P. , PANDA P.K.
Published: October 2004

We consider here the vacuum structure in QCD with both quark and gluon condensates and a variational ansatz for the ground state. The method is nonperturbative, using only equal time algebra for the field operators. We then find that a constrained energy minimization of the Hamiltonian leads to a QCD vacuum with both quark and gluon condensates for αs>αc=0.62. The pion decay constant and the charge radius of the pion seem to fix the QCD coupling constant αs as 1.28, with the bag pressure given by [Formula: see text] This approach to QCD opens up possibilities of relating the mysterious vacuum structure with common place hadronic properties in a more direct manner.
THE SECOND MOMENT OF THE STRUCTURE FUNCTION FOR PSEUDOSCALAR MESONS IN QCD SUM RULES
Authors: NISHINO YOSHINORI
Published: October 2004

We calculate the second moment [Formula: see text] of the flavor-singlet structure function [Formula: see text] for the pion and the kaon in the framework of the QCD sum rule, and investigate how the results depend on their flavor structure (quark contents). Our calculations give similar values of [Formula: see text] for these two mesons as a result of the cancellation among several non-small factors.
OPTIMIZATION OF GERMANIUM MONOCHROMATORS FOR NEUTRON DIFFRACTOMETERS
Authors: AHMED F.U. , YUNUS S.M. , KAMAL I. , BEGUM S. , KHAN AYSHA A. , AHSAN M.H. , AHMAD A.A.Z.
Published: October 2004

A computer program TISTA has been employed to study the behavior of reactor-neutrons at the sample position of a neutron spectrometer diffracted from Ge(111), (220), and (311) monochromators. Our aim is to design a double axis neutron spectrometer and to determine the behavior of beam intensity and resolution at the sample position. The study will be helpful to design experiments with the existing triple axis neutron spectrometer at TRIGA Mark II research reactor, Dhaka, Bangladesh. The optimum values of crystal and instrument parameters have been determined through these calculations. The flux density of neutrons and the resolutions of a spectrometer at the sample position have been calculated as functions of beam collimation, zero-Bragg-angle deviation, crystal curvature, distance between sample and monochromator, crystal asymmetry, thickness, mosaic spread, crystal length, etc. The present results are compared with those of copper and silicon monochromators.
QUASIPARTICLE AND PHONON EXCITATIONS IN ODD-MASS N=83 ISOTONES
Authors: LOSANO L. , DIAS H.
Published: October 2004

The structure of low-lying states in odd-mass N=83 isotones (135≤A≤151) is investigated in terms of a model in which one neutron-quasiparticle is coupled to quadrupolar and octupolar core-vibrations. Energy levels and spectroscopic factors are calculated and compared with experimental data.

Nuclear Structure: 135 Te , 137 Xe , 139 Ba , 141 Ce , 143 Nd , 145 Sm , 147 Gd , 149 Dy , and 151 Er ; calculated levels J, π, and S. Quasiparticle-phonon coupling model.
PROPERTIES OF THE RESONANCE SCATTERING IN TWO-FRAGMENT SYSTEMS FORMED IN MANY-PARTICLE NUCLEAR REACTIONS
Authors: FAZIO G. , GIARDINA G. , KARMANOV F.I. , SHABLOV V.L.
Published: October 2004

We study the possible deviations — with respect to the resonance of the isolated scattering pair — of the parameters of a two-body resonance in the field of a third particle, in the case of reactions with near-threshold resonance formation. We find that a possible description of the observed phenomenon is produced if one also uses an imaginary part in the effective potential between the resonance system and the accompanying particle. We compare our calculations for the 5 Li ** (16.66 MeV) excited state with the results of the 6 Li (3 He , αp)α experiment at E(3 He )=8–14 MeV .
EFFECTIVE NUCLEUS-NUCLEUS POTENTIAL FOR CALCULATION OF POTENTIAL ENERGY OF A DINUCLEAR SYSTEM
Authors: ADAMIAN G.G. , ANTONENKO N.V. , JOLOS R.V. , IVANOVA S.P. , MELNIKOVA O.I.
Published: October 2004

An effective method to calculate the potential energy of a dinuclear system is suggested. The nuclear part of the nucleus-nucleus potential is taken in the double folding form. The analytical expressions obtained allow one to simplify the calculations of interaction between two nuclei except the nuclei near the drip lines. The relationship between the double folding potential and the proximity potential is found. The influence of a deformation and a relative orientation of nuclei on the interaction potential is investigated. The method is applied to the calculations of the energies of the dinuclear and trinuclear systems.
ON THE COMPRESSION AND MULTIFRAGMENTATION OF NUCLEAR MATTER AT HIGH ENERGIES
Authors: KUMAR V. , SINGH B. , PALSANIA H.S. , BHALLA K.B. , LOKANATHAN S. , BADYAL S.K. , RAO N.K. , BHARTI P.
Published: October 2004

Two-particle correlations and momentum widths have been studied in case of Kr+Ag(Br) and La+Ag(Br) reactions in order to search for a physical quantity which corresponds to nuclear compression. Both the two particle correlation coefficient, B, and momentum width of alphas increase with the incident energy. Hence, they may be used to quantify nuclear compression or the nuclear density in high energy nuclear collisions.
ISOSPIN LATTICE GAS MODEL AND NUCLEAR-MATTER PHASE DIAGRAM AND PRESSURE-VOLUME ISOTHERMS
Authors: KUO T.T.S. , RAY S. , SHAMANNA J. , SU R.K.
Published: October 2004

We study a cubic lattice gas model for nuclear matter where each lattice site can be either occupied, by one proton or one neutron, or unoccupied. A nearest-neighbor interaction of the form - ∑Jijτziτzj is assumed. Our model is an isospin-1 Ising model, with τz= (1, 0, –1) representing respectively (proton, vacancy, neutron). A kinetic-energy term has been included in our model. Under the Bragg-Williams mean-field approximation our model exhibits the existence of a dense phase (liquid-like) and a rare phase (gas-like). The nuclear-matter p−v isotherms given by our model are discussed.
THE IMPACT OF KAON POLARIZATION IN NUCLEAR MATTER ON THE K− PRODUCTION IN HEAVY-ION COLLISIONS
Authors: KOLOMEITSEV E.E. , VOSKRESENSKY D.N. , KÄMPFER B.
Published: October 2004

The impact of the kaon polarization in nuclear matter on the K− yield in intermediate-energy heavy-ion collisions is investigated. Our scenario of the strange particle production and dynamics is based on an expanding fireball model. This allows for a proper account of in-medium effects. A relation between observed K+ and K− yields is derived. Differential K− cross-sections are calculated and compared with available experimental data taken at various collision energies. It turns out that in-medium effects can modify the K− yields by factors 2 to 5 at beam energies between 2 and 1 AGeV.
NONLINEAR APPROACH OF ALPHA AND CLUSTER DECAYS IN THE REACTION CHANNEL
Authors: KARTAVENKO V.G. , LUDU A. , SĂNDULESCU A. , GREINER W.
Published: October 2004

In the framework of nonlinear nuclear hydrodynamics with realistic effective Skyrme contact δ-interactions, a Schrödinger equation with a fifth order nonlinearity is deduced. By using quasi soliton-like solutions, which describe well the general properties of nuclei, we studied the behavior of alpha and cluster decays in the reaction channel. Previously, we studied the formation of clusters as solitons on nuclear surface with the help of the third order (cubic) Schrödinger equation.
NEUTRINO EMISSIVITY OF DENSE STARS
Authors: GHOSH SANJAY K. , PHATAK S.C. , SAHU P.K.
Published: October 2004

The neutrino emissivity of compact stars is investigated in this work. We consider stars consisting of nuclear as well as quark matter for this purpose. Different models are used to calculate the composition of nuclear and quark matter and the neutrino emissivity. Depending on the model under consideration, the neutrino emissivity of nuclear as well as quark matter varies over a wide range. We find that for nuclear matter, the direct URCA processes are allowed for most of the relativistic models without and with strange baryons, whereas for the nonrelativistic models this shows a strong dependence on the type of nuclear interaction employed. When the direct URCA processes are allowed, the neutrino emissivity of hadronic matter is larger than that of the quark matter by several orders of magnitude. We also find that the neutrino emissivity departs from T6 behavior when the temperature is larger than the difference in the Fermi momenta of the particles, participating in the neutrino-producing reactions.
THE UNDERLYING PHYSICS OF q-DEFORMED PSEUDOSPIN MODELS
Authors: AVANCINI S.S. , MENEZES D.P. , CRUZ F.F. DE SOUZA , DE MORAES M.M. WATANABE
Published: October 2004

In this paper, we have used the q-deformed version of the Lipkin-Meshkov-Glick (LMG) model to summarize the utilization of quantum algebras already applied to soluble pseudospin models. Within the suq(2) context, we have checked the validity of the co herent states variational method, then used the Time Dependent Hartree-Fock (TDHF) approximation to compare with the exact evolution in time of the system, and finally observed the temperature effects undergone by the system, through the study of the Helmholtz free energy. We have also investigated the LMG model within the contexts of the supq(2) and suq(3) algebras and some of the features mentioned above have been rediscussed.
QUARK POTENTIAL AT FINITE TEMPERATURE AND DISSOLUTION OF HEAVY-QUARK RESONANCES
Authors: LIU BO , DONG YU-BING
Published: October 2004

The contribution due to the Debye screening to the dissolution of heavy-quark resonances is studied by using the two different binding potentials at finite temperature in a nonrelativistic approximation. The critical values of the Debye screening length are calculated. Our calculations show that the critical values of the Debye screening length depend on the forms of the quark binding potential at finite temperature. We also estimate the critical temperature for deconfinement of heavy-quark resonances. The effects of different quark binding potentials on the dissolution for heavy-quark resonances are discussed and compared to the previous results.
AN ALLEGED DISTORTED ROTATION
Authors: NOJAROV ROLAND
Published: October 2004

The Giant Angle Dipole model describes a contrarotational (scissors) motion with superimposed deformation distortions. They cause changes in the mass and stiffness parameters and the physical observables (excitation energies and transition probabilities) corresponding to undistorted scissors motion. It is shown here that the observables, derived in this model using normalized excited states, coincide with the predictions for the low- and high-frequency modes with [Formula: see text] and 2, obtained by a recent canonical quantization of the isovector rotor, where no deformation distortions are assumed.
σ AND ω, WITH ∆-BARYON, AT HIGH TEMPERATURE
Authors: BHATTACHARYYA ABHIJIT
Published: October 2004

The temperature dependence of σ and ω meson effective masses due to the presence of Δ-baryon has been studied. Starting from the Walecka model, containing both nucleon and Δ, the temperature dependence of effective masses of nucleon and Δ have been calculated at the Mean Field (MF) level. These results have been used to calculate the contribution to the effective masses of σ and ω from both [Formula: see text]- and [Formula: see text]-loops in Random Phase Approximation (RPA). The results are quite interesting. The σ-meson mass increases due to the [Formula: see text] loop whereas it decreases due to [Formula: see text]-loop with temperature. Further, the change in σ-meson mass due to [Formula: see text]-loop is much more compared to that due to [Formula: see text]-loop. For the ω-meson, both the loops are responsible for the increase in mass with temperature.
QUANTUM CHAOS IN VIBRATIONAL NUCLEI: THE GREEN FUNCTION APPROACH
Authors: MANFREDI V.R. , ROSA-CLOT M. , TADDEI S. , SALASNICH L.
Published: October 2004

We show that the collective vibrational model of atomic nuclei displays quantum chaos. To avoid the problems related to the tunneling effects, a Green function deterministic numerical method has been used to evaluate the energy levels.
VACUUM STRUCTURE, CHIRAL SYMMETRY BREAKING AND RADIATIVE DECAYS OF BARYONS
Authors: PANDA A.R. , ROY K.C.
Published: October 2004

Radiative decays of baryons are considered in a model involving chiral symmetry breaking through a nontrivial vacuum structure. Pion and kaon, being treated consistently within the model, yield to the constituent quark wave functions approximately in the same way as the wave functions from the gap equations, and thus in a way determine the constituent quark field operators. The model had a reasonable success earlier in its applications to some low energy hadronic phenomena, and here also estimates radiative decay widths of baryons in reasonable agreement with other theoretical calculations as well as the available experimental measurements.
NUCLEAR CHARGE RADII FROM H TO Pb
Authors: ANAGNOSTATOS G.S.
Published: October 2004

The application of a new model on the charge radii for the most abundant isotopes of all elements from H to Pb is presented. The model (presented in detail elsewhere) constitutes a successful extension of the independent particle shell-model to incorporate ground state properties. The majority of radii so derived are almost within the experimental errors.
THERMAL DIMUONS AT RHIC ENERGIES
Authors: MOSTAFA M.G.-H. , WONG CHEUK-YIN , CHATTERJEE LALI , WANG ZHONG-QI
Published: October 2004

We calculate the dimuon production rate from a thermalized quark-gluon plasma in heavy-ion collisions at RHIC energies. Higher-order QCD corrections are included by using an analytical correction factor K(i), which gives very good agreement with experimental Drell-Yan data, and predicts a large enhancement of the thermal dimuon emission over the lowest order rates. We compare the thermal dimuon yields with the expected production from open-charm decays and Drell-Yan background and assess the prospects of observing thermal dimuons from the quark-gluon-plasma at invariant masses of a few GeV.
VACUUM STRUCTURE, CHIRAL SYMMETRY BREAKING AND STATIC PROPERTIES OF OCTET AND DECUPLET BARYONS
Authors: PANDA A.R. , ROY K.C. , SAHOO R.K.
Published: October 2004

The static properties of the octet and decuplet baryons are considered within the framework of a quark model of hadrons where the chiral symmetry is broken dynamically through a nontrivial vacuum structure. The pion and kaon being treated consistently within the model yield to the constituent quark wave function approximately same as the wave functions from the gap equations and thus determine consequently the constituent quark field operators. The model was successfully used earlier to study some hadronic phenomena and here also it estimates the static properties of the octet and decuplet baryons in a unified manner, in reasonable agreement with the available measurements. The only parameter of the model is the harmonic oscillator radius for the baryons. The method is nonperturbative with respect to the equal time algebra for the constituent quark field operators.
ISOSPIN DEPENDENT OSCILLATOR SPACING FOR NEUTRONS AND PROTONS IN NUCLEI USING HF-BCS RADII
Authors: LALAZISSIS G.A. , PANOS C.P.
Published: October 2004

The oscillator spacing for neutrons (ħωn) and protons (ħωp) is calculated as a function of the neutron number N and the proton number Z. The dependence of ħωn(ħωp) on N and Z is established employing a parametrization for the mean square nuclear radius obtained from HF-BCS calculations. It turns out that the difference ħωn−ħωp is appreciable, because ħω amplifies small differences of root mean square radii. It is also seen that the correction due to valence nucleons is important for relatively light and medium heavy nuclei. Satisfactory and simple approximate asymptotic formulas for ħωn(N, Z) and ħωp(N, Z) are also derived, which can be used in practice. Finally, the validity of our various approaches is checked and a possible application is also discussed.
VARIATIONAL CALCULATION OF RELATIVISTIC MESON-NUCLEON SCATTERING IN ZEROTH ORDER
Authors: SCHREIBER A.W. , ROSENFELDER R. , ALEXANDROU C.
Published: October 2004

We extend the polaron variational treatment previously developed for the propagator to the case where one nucleon and n external mesons are present. Using the particle representation of the scalar Wick-Cutkosky model this is done in lowest order of an expansion of the exact action around a retarded quadratic trial action. In particular, we evaluate the form factor for scattering of mesons from the scalar nucleon and determine the radius of the dressed particle. After analytic continuation to Minkowski space we study elastic meson-nucleon scattering both analytically and numerically near threshold and show that it is essential to incorporate the correct behavior of the retardation function at large proper times. Only if this is done the optical theorem is approximately fulfilled over a range of energies and coupling constants.
NATURAL ORBITALS AND ELECTRON ELASTIC MAGNETIC SCATTERING BY NUCLEI
Authors: KADREV D.N. , ANTONOV A.N. , STOITSOV M.V. , DIMITROVA S.S.
Published: October 2004

Natural orbitals obtained within the coherent density fluctuation model and containing nucleon correlation effects are used to calculate characteristics of the A-nucleon system, such as the electron elastic magnetic scattering form factors. The calculations are performed for nuclei with a doubly-closed core and a valence nucleon in a stretched configuration (j=l+1/2), such as the 17 O and 41 Ca nuclei. It is shown that the calculations of the transverse form factor using natural orbitals improve the agreement with the experimental data in comparison with the case when shell-model single-particle wave functions are used.
Evaluation of early gastric mucosal permeability induced by central thyrotropin-releasing hormone administration
Authors: Joh Takashi , Oshima Tadayuki , Takahashi Nobuo , Kaneko Hiroshi , Sasaki Makoto , Kataoka Hiromi , Watanabe Katsushi , Sobue Masashi , Suzuki Hideo , Nomura Tomoyuki , Ohara Hirotaka , Itoh Makoto
Published: October 2004

Accumulating evidence suggests that central thyrotropin-releasing hormone (TRH) administration induces gastric erosion 4 h after administration through the vagal nerves. However, early changes in the gastric mucosa during these 4 h have not been described. To assess early changes in the gastric mucosa after intracisternal injection of a stable TRH analog, pGlu-His-(3,3′-dimethyl)-ProNH2 (RX-77368), we measured the blood-to-lumen 51Cr-labeled EDTA clearance and examined the effects of vagotomy, atropine, omeprazole, and hydrochloric acid (HCl) on RX-77368-induced mucosal permeability. A cytoprotective dose of RX-77368 (1.5 ng) did not increase mucosal permeability. However, higher doses significantly increased mucosal permeability. Permeability peaked within 20 min and gradually returned to control levels in response to a 15-ng dose (submaximal dose). Increased mucosal permeability was not recovered after a 150-ng dose (ulcerogenic dose). This increase in permeability was inhibited by vagotomy or atropine. Intragastric perfusion with HCl did not change the RX-77368 (15 ng)-induced increase in permeability, but completely inhibited the recovery of permeability after the peak. Pretreatment with omeprazole did not change the RX-77368 (15 ng)-induced increase in permeability, but quickened the recovery of permeability after the peak. These data indicate that the RX-77368-induced increase in permeability is mediated via the vagal-cholinergic pathway and is not a secondary change in RX-77368-induced acid secretion. Inhibited recovery of permeability on exposure to an ulcerogenic RX-77368 dose or on exposure to HCl plus a submaximal dose of RX-77368 may be crucial for the induction of gastric mucosal lesions by central RX-77368 administration.
Attenuation of acute experimental colitis by preventing NPY Y1 receptor signaling
Authors: Hassani Hessameh , Lucas Guilherme , Rozell Björn , Ernfors Patrik
Published: October 2004

Neuropeptide Y (NPY), a 36-amino acid peptide, is widely expressed in the central and peripheral nervous system. NPY is involved in the regulation of several physiological processes, including energy balance, food intake, and nociception. Recently, we showed that activation of the NPY Y1 receptor is required for cutaneous neurogenic inflammation. Because neurogenic inflammation could participate in colitis, the aim of this study was to investigate the role of the NPY Y1 receptor in acute colitis using mice genetically deficient of NPY Y1 receptor. In addition, the Y1 receptor antagonist H409/22, was also investigated. Animals received 5% dextran sulfate sodium (DSS) in drinking water for 7 days. One group of animals also received the Y1 receptor antagonist, administered intraperitoneally twice daily. Disease activity was assessed daily for 7 days in all groups. DSS induced colitis in all animals resulting in weight loss, diarrhea, epithelial damage, crypt shortening, and inflammatory infiltration. However, clinical manifestation of the disease was markedly attenuated in Y1 null mutant mice as well as in mice receiving the Y1 antagonist. Histological analysis showed that tissue damage and ulceration were less severe in Y1-deficient animals. Consistent with the clinical and histological data, capsaicin-induced plasma extravasation was significantly reduced in the gut of Y1 null mutant animals compared with treated wild-type animals. These data indicate that NPY and Y1 receptor are involved in intestinal inflammation and suggest that inhibition of NPY Y1 receptor signaling may provide a novel therapeutic approach in the treatment of colonic inflammation.
Mechanism of augmented duodenal HCO3−secretion after elevation of luminal CO2
Authors: Furukawa Osamu , Hirokawa Masahiko , Zhang Lening , Takeuchi Tetsu , Bi Luke C. , Guth Paul H. , Engel Eli , Akiba Yasutada , Kaunitz Jonathan D.
Published: October 2004

The proximal duodenum is exposed to extreme elevations of Pco2because of the continuous mixture of secreted HCO3−with gastric acid. These elevations (up to 80 kPa) are likely to place the mucosal cells under severe acid stress. Furthermore, we hypothesized that, unlike most other cells, the principal source of CO2for duodenal epithelial cells is from the lumen. We hence examined the effect of elevated luminal Pco2on duodenal HCO3−secretion (DBS) in the rat. DBS was measured by the pH-stat method. For CO2challenge, the duodenum was superfused with a high Pco2solution. Intracellular pH (pHi) of duodenal epithelial cells was measured by ratio microfluorometry. CO2challenge, but not isohydric solutions, strongly increased DBS to approximately two times basal for up to 1 h. Preperfusion of the membrane-permeant carbonic anhydrase inhibitor methazolamide, or continuous exposure with indomethacin, fully inhibited CO2-augmented DBS. Dimethyl amiloride (0.1 mM), an inhibitor of the basolateral sodium-hydrogen exchanger 1, also inhibited CO2-augumented DBS, although S-3226, a specific inhibitor of apical sodium-hydrogen exchanger 3, did not. DIDS, an inhibitor of basolateral sodium-HCO3−cotransporter, also inhibited CO2-augemented DBS, as did the anion channel inhibitor 5-nitro-2-(3-phenylpropylamino) benzoic acid. CO2decreased epithelial cell pHi, followed by an overshoot after removal of the CO2solution. We conclude that luminal CO2diffused in the duodenal epithelial cells and was converted to H+and HCO3−by carbonic anhydrase. H+initially exited the cell, followed by secretion of HCO3−. Secretion was dependent on a functioning basolateral sodium/proton exchanger, a functioning basolateral HCO3−uptake mechanism, and submucosal prostaglandin generation and facilitated hydration of CO2into HCO3−and H+.
Toll-like receptor-mediated responses of primary intestinal epithelial cells during the development of colitis
Authors: Singh Joy Carmelina Indira , Cruickshank Sheena Margaret , Newton Darren James , Wakenshaw Louise , Graham Anne , Lan Jinggang , Lodge Jeremy Peter Alan , Felsburg Peter John , Carding Simon Richard
Published: October 2004

The interleukin-2-deficient (IL-2−/−) mouse model of ulcerative colitis was used to test the hypothesis that colonic epithelial cells (CEC) directly respond to bacterial antigens and that alterations in Toll-like receptor (TLR)-mediated signaling may occur during the development of colitis. TLR expression and activation of TLR-mediated signaling pathways in primary CEC of healthy animals was compared with CEC in IL-2−/−mice during the development of colitis. In healthy animals, CEC expressed functional TLR, and in response to the TLR4 ligand LPS, proliferated and secreted the cytokines IL-6 and monocyte chemoattractant protein-1 (MCP-1). However, the TLR-responsiveness of CEC in IL-2−/−mice was different with decreased TLR4 responsiveness and augmented TLR2 responses that result in IL-6 and MCP-1 secretion. TLR signaling in CEC did not involve NF-κB (p65) activation with the inhibitory p50 form of NF-κB predominating in CEC in both the healthy and inflamed colon. Development of colitis was, however, associated with the activation of MAPK family members and upregulation of MyD88-independent signaling pathways characterized by increased caspase-1 activity and IL-18 production. These findings identify changes in TLR expression and signaling during the development of colitis that may contribute to changes in the host response to bacterial antigens seen in colitis.
Characterization of intracellular Ca2+ stores in gallbladder smooth muscle
Authors: Morales Sara , Camello Pedro J. , Mawe Gary M. , Pozo María J.
Published: October 2004

The existence of functionally distinct intracellular Ca2+ stores has been proposed in some types of smooth muscle. In this study, we sought to examine Ca2+ stores in the gallbladder by measuring intracellular Ca2+ concentration ([Ca2+]i) in fura 2-loaded isolated myocytes, membrane potential in intact smooth muscle, and isometric contractions in whole mount preparations. Exposure of isolated myocytes to 10 nM CCK caused a transient elevation in [Ca2+]i that persisted in Ca2+-free medium and was inhibited by 2-aminoethoxydiphenylborane (2-APB). Application of caffeine induced a rapid spike-like elevation in [Ca2+]i that was insensitive to 2-APB but was abolished by pretreatment with 10 μM ryanodine. These data support the idea that both inositol trisphosphate (IP3) receptors (IP3R) and ryanodine receptors (RyR) are present in this tissue. When caffeine was applied in Ca2+-free solution, the [Ca2+]i transients decreased as the interval between Ca2+ removal and caffeine application was increased, indicating a possible leakage of Ca2+ in these stores. The refilling of caffeine-sensitive stores involved sarcoendoplasmic reticulum Ca2+-ATPase activation, similar to IP3-sensitive stores. The moderate Ca2+ elevation caused by CCK was associated with a gallbladder contraction, but caffeine or ryanodine failed to induce gallbladder contraction. Nevertheless, caffeine caused a concentration-dependent relaxation in gallbladder strips either under resting tone conditions or precontracted with 1 μM CCK. Taken together, these results suggest that, in gallbladder smooth muscle, multiple pharmacologically distinct Ca2+ pools do not exist, but IP3R and RyR must be spatially separated because Ca2+ release via these pathways leads to opposite responses.
Remote preconditioning reduces ischemic injury in the explanted heart by a KATP channel-dependent mechanism
Authors: Kristiansen Steen B. , Henning Ole , Kharbanda Rajesh K. , Nielsen-Kudsk Jens Erik , Schmidt Michael Rahbek , Redington Andrew N. , Nielsen Torsten Toftegaard , Bøtker Hans Erik
Published: October 2004

Local and remote ischemic preconditioning (IPC) reduce ischemia-reperfusion (I/R) injury and preserve cardiac function. In this study, we tested the hypothesis that remote preconditioning is memorized by the explanted heart and yields protection from subsequent I/R injury and that the underlying mechanism involves sarcolemmal and mitochondrial ATP-sensitive K+ (KATP) channels. Male Wistar rats (300–350 g) were randomized to a control ( n = 10), a remote IPC ( n = 10), and a local IPC group ( n = 10). Remote IPC was induced by four cycles of 5 min of limb ischemia, followed by 5 min of reperfusion. Local IPC was induced by four cycles of 2 min of regional myocardial ischemia, followed by 3 min of reperfusion. The heart was excised within 5 min after the final cycle of preconditioning, mounted in a perfused Langendorff preparation for 40 min of stabilization, and subjected to 45 min of sustained ischemia by occluding the left coronary artery and 120 min of reperfusion. I/R injury was assessed as infarct size by triphenyltetrazolium staining. The influence of sarcolemmal and mitochondrial KATP channels on remote preconditioning was assessed by the addition of glibenclamide (10 μM, a nonselective KATP blocker), 5-hydroxydecanoic acid (5-HD; 100 μM, a mitochondrial KATP blocker), and HMR-1098 (30 μM, a sarcolemmal KATP blocker) to the Langendorff preparation before I/R. The role of mitochondrial KATP channels as an effector mechanism for memorizing remote preconditioning was further studied by the effect of the specific mitochondrial KATP activator diaxozide (10 mg/kg) on myocardial infarct size. Remote preconditioning reduced I/R injury in the explanted heart (0.17 ± 0.03 vs. 0.39 ± 0.05, P < 0.05) and improved left ventricular function during reperfusion compared with control ( P < 0.05). Similar effects were obtained with diazoxide. Remote preconditioning was abolished by the addition of 5-HD and glibenclamide but not by HMR-1098. In conclusion, the protective effect of remote preconditioning is memorized in the explanted heart by a mechanism that involves mitochondrial KATP channels.
Human neutrophils promote angiogenesis by a paracrine feedforward mechanism involving endothelial interleukin-8
Authors: Schruefer Ruth , Lutze Nicola , Schymeinsky Jürgen , Walzog Barbara
Published: October 2004

Neovascularization by sprouting angiogenesis is critical for inflammation-mediated tissue remodeling and wound healing. We report here that human polymorphonuclear neutrophils (PMN) stimulated for 1 h with 100 nM N-formyl-methionyl-leucyl-phenylalanine (fMLP) released a proangiogenic entity that induced sprouting of capillary-like structures in an in vitro angiogenesis assay. The effect was comparable to the response obtained on stimulation with 100 ng/ml basic FGF. The PMN-mediated response was inhibited by neutralizing antibodies against VEGF or IL-8. As measured by ELISA technique, we found that fMLP-activated PMN (5 × 106/ml) released 78 pg/ml IL-8 and 39 pg/ml VEGF within 1 h after stimulation. IL-8 release was blocked by actinomycin D or cycloheximide, but the inhibitors had no effect on VEGF release, suggesting that IL-8 secretion required de novo synthesis whereas VEGF was secreted from preformed stores. Accordingly, RT-PCR analysis revealed that IL-8 mRNA was upregulated on PMN stimulation, whereas the expression of VEGF mRNA was not affected. Moreover, supernatant derived from activated PMN induced upregulation of endothelial IL-8 mRNA expression, suggesting that release of VEGF and IL-8 from activated PMN may activate a paracrine feedforward mechanism involving endothelial IL-8. Moreover, VEGF-induced upregulation of endothelial IL-8 expression as well as sprouting of capillary-like structures was inhibited by a neutralizing anti-IL-8 antibody. These findings suggest that bacteria-derived tripeptides stimulate human PMN to release VEGF and IL-8, which activate endothelial cells and induce angiogenesis by a paracrine feedforward mechanism involving endothelial IL-8 upregulation.
Role of impaired myocardial relaxation in the production of elevated left ventricular filling pressure
Authors: Hay Ilan , Rich Jonathan , Ferber Paul , Burkhoff Daniel , Maurer Mathew S.
Published: October 2004

Although present in many patients with heart failure and a normal ejection fraction, the role of isolated impairments in active myocardial relaxation in the genesis of elevated filling pressures is not well characterized. Because of difficulties in determining the effect of prolonged myocardial relaxation in vivo, we used a cardiovascular simulated computer model. The effect of myocardial relaxation, as assessed by τ (exponential time constant of relaxation), on pulmonary vein pressure (PVP) and left ventricular end-diastolic pressure (LVEDP) was investigated over a wide range of τ values (20–100 ms) and heart rate (60–140 beats/min) while keeping end-diastolic volume constant. Cardiac output was recorded over a wide range of τ and heart rate while keeping PVP constant. The effect of systolic intervals was investigated by changing time to end systole at the same heart rate. At a heart rate of 60 beats/min, increases in τ from a baseline to extreme value of 100 ms cause only a minor increase in PVP of 3 mmHg. In contrast, at 120 beats/min, the same increase in τ increases PVP by 23 mmHg. An increase in filling pressures at high heart rates was attributable to incomplete relaxation. The PVP-LVEDP gradient was not constant and increased with increasing τ and heart rate. Prolonged systolic intervals augmented the effects of τ on PVP. Impaired myocardial relaxation is an important determinant of PVP and cardiac output only during rapid heart rate and especially when combined with prolonged systolic intervals. These findings clarify the role of myocardial relaxation in the pathogenesis of elevated filling pressures characteristic of heart failure.
Cardiac and renal effects of omapatrilat, a vasopeptidase inhibitor, in rats with experimental congestive heart failure
Authors: Abassi Zaid A. , Yahia Ali , Zeid Samar , Karram Tony , Golomb Eliahu , Winaver Joseph , Hoffman Aaron
Published: October 2004

Omapatrilat (OMP) is a novel mixed inhibitor of angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP), the enzyme that metabolizes natriuretic peptides. Congestive heart failure (CHF) is characterized by excessive sodium retention, attributed to both an excessive effect of angiotensin II and diminished responsiveness to natriuretic peptides. In this study, we examined the acute and chronic renal and cardiac effects of OMP in rats with compensated [urinary sodium excretion (UNaV) > 1,200 μeq/day] and decompensated (UNaV < 100 μeq/day) CHF, induced by a surgical aortocaval fistula (ACF). Bolus injection of OMP (10 mg/kg) to sham controls produced significant diuretic and natriuretic responses [UNaV increased from 0.67 ± 0.19 to 3.27 ± 1.35 μeq/min, P < 0.05; fractional sodium excretion (FENa) increased from 0.23 ± 0.06 to 0.95 ± 0.34%, P < 0.01] despite a significant decline in blood pressure (BP). Rats with compensated CHF displayed blunted diuresis and natriuresis to this dose of OMP but a significant decrease in BP. However, in rats with decompensated CHF, OMP induced significant natriuresis (FENa increased from 0.18 ± 0.15 to 0.82 ± 0.26%, P < 0.05) despite a further decrease in BP (from 90 ± 9 to 71 ± 6 mmHg, P < 0.01). Two weeks after ACF, the heart/body weight ratio was significantly greater in rats with CHF than controls (0.51 ± 0.026 vs. 0.30 ± 0.004%, P < 0.0001), and UNaV was significantly lower. Immediate or late (1 or 6 days after ACF) OMP treatment in the drinking water (140 mg/l) reduced cardiac hypertrophy to 0.41–0.43% ( P < 0.01) and induced natriuresis. These results suggest that OMP improves both sodium balance and cardiac remodeling and might be advantageous to ACE inhibitors for the treatment of decompensated CHF.