bluuebunny/crossref_metadata_2025 huggingface dataset:
KUBO-ANDERSON MIXING IN THE TURBULENT BOUNDARY LAYER
Authors: DEKKER H. , DE LEEUW G. , BRINK A. MAASSEN VAN DEN
Published: November 2004

A novel ab initio analysis of the Reynolds stress is presented in order to model non-local turbulence transport. The theory involves a sample path space and a stochastic hypothesis. A scaling relation maps the path space onto the boundary layer. Analytical sampling rates are shown to model mixing by exchange. Nonlocal mixing involves a scaling exponent ε≈0.58 (ε→∞ in the diffusion limit). The resulting transport equation represents a nondiffusive (Kubo-Anderson or kangaroo) type stochastic process.
MAGNETORESISTANCE IN Bi1.8Pb0.4Sr2Ca2Cu3Oy THICK FILM
Authors: ZHIHE WANG , HANMIN HAN , GUCHANG HAN , SHUNXI WANG
Published: November 2004

The magnetoresistance curves of Bi(2223) thick film were measured near T c with applied magnetic field parallel and perpendicular to the c axis ranging up to 0.12 T. The results show that thermally activated flux flow region does not exist very close to T c and magnetoresistive transition can be well described by a thermally activated flux flow process below 108.5 K and at lower magnetic field. The relation between applied magnetic field H and temperature T was found to fit with “irreversibility line.”
IRREVERSIBILITY IN RELATIVISTIC STATISTICAL MECHANICS
Authors: BEN-YA’ACOV URI
Published: November 2004

Relativistic statistical mechanics should be manifestly Lorentz covariant. In the absence of a Hamiltonian formalism in relativistic dynamics, a different approach which is based on the (Lagrangian) equations of motion is presented. Without any Liouville equation, this approach provides the direct computation of all the reduced n-particle distribution functions. The trajectories in the fully interacting system and ensemble averages are defined with respect to the parameters that fix the trajectories in the interaction-free limit. Irreversibility may emerge from microscopic dynamics due to the choice as to which part of the particles’ history — past or future — contributes to the interaction. Irreversibility is explicitly demonstrated in the evolution of the one-particle distribution function.
ON THE UNIQUENESS OF SOLUTIONS TO THE DRIFT-DIFFUSION MODEL OF SEMICONDUCTOR DEVICES
Authors: GAJEWSKI HERBERT
Published: November 2004

We prove a uniqueness result for the drift-diffusion model of semiconductor devices under weak regularity assumptions. Our proof rests on the convexity of the free energy functional and uses a new concavity argument.
SOME REMARKS ON STACKELBERG’S OPTIMIZATION
Authors: LIONS J.L.
Published: November 2004

We consider a distributed system governed by a parabolic equation, with a control v distributed over a subdomain [Formula: see text]. We assume that there are two goals we would like to achieve. The main one being of the “controllability” type, the “second one” expressing that the state of the system does not move “too far” from a given state.

We introduce the following method. We divide v into two parts, say v1, v2, corresponding to a division of [Formula: see text] into two parts [Formula: see text]. Then we use the notion of Stackelberg’s optimization (introduced and used in Economy), where v2 is the follower and v1 the leader. Assuming that v1 is given, we optimize the second criterion with respect to v2, which gives v2=ℱ(v1) a function of v1. Then the first criterion becomes a function of v1 alone. It is of the approximate controllability type. In order to solve it, one has to prove a density theorem, which amounts to a uniqueness theorem, where we use a uniqueness theorem of Mizohata and regularity theorems of Cavalluci and of Matsuzawa.
ON THE EXISTENCE AND UNIQUENESS OF TRANSIENT SOLUTIONS OF A DEGENERATE NONLINEAR DRIFT-DIFFUSION MODEL FOR SEMICONDUCTORS
Authors: JÜNGEL ANSGAR
Published: November 2004

We analyze the degenerate transient multi-dimensional quasi-hydrodynamic model for semiconductors with general recombination rate. We present existence results for general nonlinear diffusivities for the nondegenerate and the degenerate Dirichlet-Neumann mixed boundary value problem. Uniqueness of solutions of the nondegenerate system can be proved in the Dirichlet boundary case. Concerning the degenerate problem uniqueness can only be shown under some conditions on the initial and boundary data or on the electric field.
ON STABILIZING AGAINST MODELING ERRORS IN A PENETRATIVE CONVECTION PROBLEM FOR A POROUS MEDIUM
Authors: AMES K.A. , PAYNE L.E.
Published: November 2004

Continuous dependence on modeling results are derived for an ill-posed problem describing penetrative convection in a porous medium. Using a logarithmic convexity argument, we show that solutions to the governing equations backward in time depend Hölder continuously on changes in the form of the buoyancy law provided they satisfy certain constraints.
HIDDEN SYMMETRIES, SPECIAL GEOMETRY AND QUATERNIONIC MANIFOLDS
Authors: DE WIT B. , VAN PROEYEN A.
Published: November 2004

The moduli space of the Calabi-Yau three-folds, which play a role as superstring ground states, exhibits the same special geometry that is known from nonlinear sigma models in N=2 supergravity theories. We discuss the symmetry structure of special real, complex and quaternionic spaces. Maps between these spaces are implemented via dimensional reduction. We analyze the emergence of extra and hidden symmetries. This analysis is then applied to homogeneous special spaces and the implications for the classification of homogeneous quaternionic spaces are discussed.
HOW FAST DOES A BLACK HOLE RADIATE INFORMATION?
Authors: PAGE DON N
Published: November 2004

If the information that falls into a black hole comes back out in the Hawking radiation, how fast might it be expected to do so? An estimate based on the average entropy of a subsystem shows that it may come out so slowly in the initial stages of black hole evaporation that it would never be predicted by a perturbative analysis.
PERFECT FLUID PERTURBATIONS OF ROBERTSON-WALKER SPACETIMES
Authors: BOMBELLI LUCA
Published: November 2004

I report on recent work on perturbations of Robertson-Walker spacetimes using the Bardeen-Stewart variables to describe metric perturbations. The gauge freedom available in the formalism is larger than that arising purely from spacetime diffeomorphisms. The associated non-uniqueness and non-locality problems have a simple solution, but the extra gauge freedom must be taken into account to obtain deterministic linearized field equations. The linearized Einstein equation decouples into scalar, vector and tensor sectors; I write down and comment on the equations one obtains using as matter an isentropic perfect fluid.
GENERAL RELATIVISTIC FRAMEWORK FOR ATOMIC INTERFEROMETRY
Authors: BORDÉ Christian J. , KARASIEWICZ A. , TOURRENC Ph.
Published: November 2004

We give covariant equations for a two-level spin 1/2 atom interacting with laser fields in a gravitational background. Some gravitational effects of interest for atomic interferometry are derived, including spin-gravitation effects. A possible application to gravitational wave detection is outlined.
QUANTUM STATE AND SPONTANEOUS SYMMETRY BREAKING IN GRAVITY
Authors: GONZALEZ-DIAZ PEDRO F.
Published: November 2004

A spontaneous symmetry breaking mechanism is used in quantum gravity to obtain a convergent positive definite density-matrix as the most general quantum state of Euclidean wormholes.
MULTIPARTICLE SOLUTIONS IN 2+1 GRAVITY AND TIME MACHINES
Authors: STEIF ALAN R.
Published: November 2004

Multiparticle solutions for sources moving at the speed of light and corresponding to superpositions of single-particle plane-wave solutions are constructed in 2+1 gravity. It is shown that the two-particle spacetimes admit closed timelike curves provided the center-of-momentum energy exceeds a certain critical value. This occurs, however, at the cost of unphysical boundary conditions which are analogous to those affecting Gott’s time machine. As the energy exceeds the critical value, the closed timelike curves first occur at spatial infinity, then migrate inward as the energy is further increased. The total mass of the system also becomes imaginary for particle energies greater than the critical value.
REDUCED PHASE SPACE QUANTIZATION OF SPHERICALLY SYMMETRIC EINSTEIN-MAXWELL THEORY INCLUDING A COSMOLOGICAL CONSTANT
Authors: Thiemann T.
Published: November 2004

We present here the canonical treatment of spherically symmetric (quantum) gravity coupled to spherically symmetric Maxwell theory with or without a cosmological constant. The quantization is based on the reduced phase space which is coordinatized by the mass and the electric charge as well as their canonically conjugate momenta, whose geometrical interpretation is explored.

The dimension of the reduced phase space depends on the topology chosen, quite similar to the case of pure (2+1) gravity. We also compare the reduced phase space quantization to the algebraic quantization.

Altogether, we observe that the present model serves as an interesting testing ground for full (3+1) gravity.

We use the new canonical variables introduced by Ashtekar which simplifies the analysis tremendously.
NEW RESULTS IN BLACK HOLE PHYSICS
Authors: WHITING BERNARD F.
Published: November 2004

Brief statements are given on recent results in the following areas: 1) The derivation of a variational (maximum) principle for black hole entropy, and an outline of the physically reasonable properties of the related solution for the density of states in the microcanonical equilibrium ensemble (with Jeffrey Melmed, University of Maine). 2) Analysis of topological contributions to black hole entropy in Lovelock gravity, and the corresponding thermodynamic identity (with Jonathan Z. Simon, University of Maryland). 3) Stability analysis for a shell of matter surrounding a black hole in microcanonical (thermal) equilibrium (with Gerald Horwitz, Hebrew University, Jerusalem)—results from this work can be compared with an earlier analysis of the purely mechanical stability of the shell, and with known properties of both the dynamical and thermal stability for the black hole without a shell. 4) The study of a simple ‘singularity'-free model of gravitational collapse, and an examination of the relationship between the ensuing preservation of quantum coherence and the usual perception that mixed states should be associated with the late time emission of Hawking radiation from a classically formed black hole (with Gerard ’t Hooft and Chris Stephens, University of Utrecht).
GENERAL RELATIVITY AS A THEORY OF TWO CONNECTIONS
Authors: BARBERO G. J. FERNANDO
Published: November 2004

We show in this paper that it is possible to formulate general relativity in a phase space coordinatized by two SO(3) connections. We analyze first the Husain-Kuchař model and find a two connection description for it. Introducing a suitable scalar constraint in this phase space we get a Hamiltonian formulation of gravity that is close to the one given by Ashtekar, from which it is derived, but has some interesting features of its own. Among them are a possible mechanism for dealing with the degenerate metrics and a neat way of writing the constraints of general relativity.
CONSERVED QUANTITIES IN PERTURBED INFLATIONARY UNIVERSES
Authors: DUNSBY PETER K.S. , BRUNI MARCO
Published: November 2004

Given that observations seem to favour a density parameter Ω0<1, corresponding to an open universe, we consider gauge-invariant perturbations of nonflat Robertson-Walker universes filled with a general imperfect fluid which can also be taken to represent a scalar field. Our aim is to set up the equations that govern the evolution of the density perturbations Δ so that it can be determined through a first order differential equation with a quantity [Formula: see text] which is conserved at any length scale, even in nonflat universe models, acting as a source term. The quantity [Formula: see text] generalizes other variables that are conserved in specific cases (for example at large scales in a flat universe) and is useful to connect different epochs in the evolution of density perturbations via a transfer function. We show that the problem of finding a conserved [Formula: see text] can be reduced to determining two auxiliary variables X and Y, and illustrate the method with two simple examples.
QUANTUM STATE OF WORMHOLES AND TOPOLOGICAL ARROW OF TIME
Authors: GONZÁLEZ-DĺAZ PEDRO F.
Published: November 2004

This paper studies the time-symmetry problem in quantum gravity. The issue depends critically on the choice of the quantum state and has been considered in this paper by restricting it to the case of quantum wormholes. It is seen that pure states represented by a wave functional are time symmetric. However, a maximal analytic extension of the wormhole manifold is found that corresponds to a mixed state describable by a nondegenerate density-matrix functional that involves an extra quantum uncertainty for the three-metric, and is free from the divergences encountered so far in statistical states formulated in quantum gravity. It is then argued that, relative to one asymptotic region, the statistical quantum state of single Euclidean wormholes in semiclassical approximation is time-asymmetric and gives rise to a topological arrow of time which will reflect in the set of all quantum fields at low energies of the asymptotically flat region.
CAN THE INTERACTION BETWEEN BABY UNIVERSES GENERATE A BIG UNIVERSE?
Authors: CAVAGLIÀ MARCO
Published: November 2004

We explore a simple toy model of interacting universes to establish that a small baby universe could become large (≫ Planck length) if a third quantization mechanism is taken into account.
PLANE SYMMETRIC VISCOUS-FLUID COSMOLOGICAL MODELS WITH HEAT FLUX
Authors: PATEL L.K. , DESAI LAKSHMI S.
Published: November 2004

A class of nonstatic inhomogeneous plane-symmetric solutions of Einstein field equations is obtained. The source for these solutions is a viscous fluid with heat flow. The fluid flow is irrotational and it has nonzero expansion, shear and acceleration. All these solutions have a big-bang singularity. The matter-free limit of the solutions is the well-known Kasner vacuum solution. Some physical features of the solutions are briefly discussed.
SEPARATION OF VARIABLES FOR THE DIRAC SQUARE EQUATION
Authors: BAGROV V.G. , OBUKHOV V.V.
Published: November 2004

The problem of separation of variables for the Dirac square equation on a curved space-time in the presence of electromagnetic potential is considered. It is shown that the necessary condition for the separation of variables in the Dirac square equation is the complete separation of variables in the related Hamilton-Jacobi equation, i.e. the Riemann space should be Stäckel. The constructive scheme for separation procedure is presented.
ON TWO-BODY SPACE EXPERIMENTS FOR MEASURING GRAVITATIONAL INTERACTION PARAMETERS
Authors: ALEXEEV A.D. , BRONNIKOV K.A. , KOLOSNITSYN N.I. , KONSTANTINOV M. Yu. , MELNIKOV V.N. , RADYNOV A.G.
Published: November 2004

Recently two methods of measuring the gravitational constant G, possible equivalence principle violation (measured by the Eötvös parameter η) and the hypothetic 5th force parameters α and λ on board a drag-free Earth’s satellite were suggested: SEE (Satellite Energy Exchange) and LPH (Libration Point Hitting). These methods are developed and compared. Various particle trajectories near a heavy ball are studied numerically and analytically. Some basic sources of error are analysed. The G measurement procedure is modelled by noise insertion to a “true” trajectory. It is concluded that the presense knowledge of G, α (for λ≥1 m) and η can be improved by at least two orders of magnitude.
DARK MATTER AND DYNAMICS IN HERCULES CLUSTER
Authors: Bird Christina M. , Dickey John M. , Salpeter E.E.
Published: November 2004

We present new 21-cm observations of faint (15.7<mpg<16.5) spiral galaxies in the Abell cluster 2151. These results, when combined with the large body of velocities available in the literature for Hercules, permit us to study the dynamics throughout the cluster core, out to a projected radius of 1.8h−1 Mpc.

We calculate the global dynamical mass of Hercules using 3 different but related methods: two versions of the virial theorem and the projected mass estimator. These masses lie in the range 3–6×1014 M⊙.

We investigate the importance of subclustering in A2151 using the statistical test of Dressler and Shectman1 and the effects of the detected substructure on the dynamical mass determination. The clumpy distribution of galaxies is interpreted as a sign that the galaxies in the cluster have not reached dynamical equilibrium in the gravitational potential, which means that dynamical mass estimates are prone to significant errors. In spite of this uncertainty, we estimate that the virial theorem errors due to the presence of substructure are not larger than 30% in A2151.

Finally, we use the 21-cm linewidths to estimate the minimum total mass in the cluster which is contained within the HI radii of the cluster galaxies is about 3×1014 M⊙. This number may be compared with the dynamical mass and used to separate the contribution of dark matter inside and outside the HI envelopes of galaxies, and the fraction of DM which cannot be associated with individual galaxies, about 90–95%.
COLOR TRANSPARENCY: FACTS AND FANCY
Authors: NIKOLAEV N.N.
Published: November 2004

This is a review of the principal motivations behind, and the status of, color transparency physics, with particular emphasis on the effects of a large coherence length at high energies.
NEUTRINO-NUCLEUS REACTIONS
Authors: KUBODERA KUNIHARU , NOZAWA SATOSHI
Published: November 2004

This is a review of the current status of theoretical treatments of neutrino-nucleus reactions that are relevant to the detection of astrophysical neutrinos. Various nuclear physics aspects involved in the evaluation of the neutrino-nucleus reaction cross-sections are critically surveyed.
VARIATIONAL DESCRIPTION OF THE ROTATING NUCLEI
Authors: NAWROCKA W. , NAZMITDINOV R.G,
Published: November 2004

Pairing vibrations in strongly rotating nuclei are treated using the variational approach. The residual interaction is assumed to be due to monopole pairing. A simple generalization of the standard BCS plus RPA enables us to obtain the set of mutually dependent equations describing the quasi-particles and the pairing vibrational phonons.
CORRELATIONS IN NUCLEI AND NUCLEAR DYNAMICS
Authors: REINHARD P.-G. , TOEPFFER C.
Published: November 2004

A wide variety of schemes to compute short-range and long-range correlations is discussed. The emphasis lies on an overview and on the interrelations between the various schemes, rather than on a detailed presentation. The need for effective interactions, and their proper handling is outlined at the end.
FINITE SIZE EFFECTS IN THE ELECTROMAGNETIC QUASI-ELASTIC RESPONSES OF NUCLEI
Authors: AMARO J.E. , LALLENA A.M. , CO’ G.
Published: November 2004

The effects of the finite size of the nucleus in the electromagnetic excitation of the quasi-elastic peak have been studied by comparing the responses calculated for 12C and 40Ca with the Fermi gas and the shell model. The contribution of the Meson Exchange Currents has also been considered. We have investigated the possibility of improving the Fermi gas model with approximate estimations of the finite size effects. We found that the use of an effective Fermi momentum provides a better description of the shell model results than the Local Density Approximation.
DESCRIPTION OF E1 TRANSITION IN DOUBLY EVEN WELL-DEFORMED NUCLEI
Authors: SOLOVIEV V.G. , SUSHKOV A.V. , SHIRIKOVA N. YU.
Published: November 2004

One-phonon states with Kπ=0− and 1− are calculated within the RPA taking the isoscalar and isovector particle-hole and particle-particle octupole and isovector particlehole dipole interactions into account. General equations of the Quasiparticle-Phonon Nuclear Model are modified. The energies and wave functions of the nonrotational states below 2.3 MeV in 160Gd calculated within this model are in good overall agreement with experimental data. The E1 transition rates in several doubly even well-deformed nuclei are calculated. The influence of the radial dependence of the dipole and octupole interactions on E1 and E3 transition probabilities is investigated. It is shown that the fragmentation of one-phonon states below 2.3 MeV weakly affects the E1 transition rates from 1− states to the ground state. The fragmentation of one- and two-phonon states strongly affect B(E1) values of the transitions from 1− states with energy above 2.5 MeV to the ground states and between excited states. The results of calculating the E1 transition rates are compared with the relevant experimental data.
Cerebrospinal Fluid Profile of Amyloid β Peptides in Patients with Alzheimer’s Disease Determined by Protein Biochip Technology
Authors: Maddalena Alessia S. , Papassotiropoulos Andreas , Gonzalez-Agosti Charo , Signorell Andri , Hegi Thomas , Pasch Thomas , Nitsch Roger M. , Hock Christoph
Published: November 2004

Amyloid-β peptides (Aβ) are major components of amyloid plaques in the Alzheimer’s disease (AD) brain and have been proposed as diagnostic markers in cerebrospinal fluid (CSF). Aβ derived from brain may be processed into fragments before emerging in CSF. Therefore, we determined mass profiles of Aβ peptides in CSF of patients with AD and age-matched healthy control subjects (CTR) by using protein biochip technology. Aβ peptides were captured on the chip surfaces (spots) by the specific monoclonal antibody 6E10 and were then analyzed by integrated surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF-MS). We found Aβ species with mean molecular masses at 1,583.3 Da (corresponding to Aβ2–14), 2,068.5 Da (Aβ1–17), 2,166.4 Da (Aβ1–18), 3,676.6 Da (Aβ1–33), 3,789.4 Da (Aβ1–34), 4,076.9 Da (Aβ1–37), 4,134.0 Da (Aβ1–38), 4,233.3 Da (Aβ1–39), 4,332.4 Da (Aβ1–40) and 4,516.8 Da (Aβ1–42) in both AD (n = 24) and CTR (n = 24) subjects. Aβ1–38 appeared to be a major Aβ species in human CSF along with Aβ1–40. Quantitation revealed that CSF levels of Aβ1–38 were significantly decreased in AD as compared to CTR subjects. The CSF profile of Aβ peptides may be used for diagnostic and therapeutic purposes in clinical studies.
Prognostic value of pretransplantation host thymic function in HLA-identical sibling hematopoietic stem cell transplantation
Authors: Clave Emmanuel , Rocha Vanderson , Talvensaari Kimmo , Busson Marc , Douay Corinne , Appert Marie-Lorraine , Rabian Claire , Carmagnat Maryvonnick , Garnier Federico , Filion Alain , Socié Gérard , Gluckman Eliane , Charron Dominique , Toubert Antoine
Published: November 2004

Thymic function is critical for immune reconstitution after hematopoietic stem cell transplantation (HSCT). We evaluated recipient thymic function before HSCT by quantifying T-cell receptor excision circles (TRECs) in pretransplantation peripheral blood lymphocytes from 102 patients who received HSCs from an HLA-identical sibling for malignant (n = 87) or nonmalignant diseases (n = 15). Median TREC value before transplantation was 257 TRECs per 150 000 CD3+ cells (range, 0-42 746). We assessed 172 TRECs per 150 000 CD3+ cells as the most discriminating TREC value for survival in a first cohort of patients (n = 62). This cut-off was validated in a second independent prospective group of 40 patients. In the 102 patients, a TREC value greater than or equal to 172 was associated with a better survival (P < .000 01), a decreased incidence of grade II-IV acute graft-versus-host disease (GVHD; P = .017), chronic GVHD (P = .023), and bacterial (P = .003) and cytomegalovirus (CMV) infection (P = .024). In a multivariate analysis, low pretransplantation TREC values were associated with a higher incidence of CMV infection (hazard ratio [HR] = 2.0, P = .06) and severe bacterial infections (HR = 2.8, P = .036). Finally, high TREC values (HR = 6.6, P = .002) and ABO compatibility (HR = 2.7, P = .02) were associated with a better survival. Therefore, recipient host thymic function assessment could be helpful in predicting HSCT outcome and identifying patients who require a close immunologic monitoring.
Effects and indications of sacral surface therapeutic electrical stimulation in refractory urinary incontinence
Authors: Yokozuka Mieko , Namima Takashige , Nakagawa Haruo , Ichie Masayoshi , Handa Yasunobu
Published: November 2004

Objective: To describe the effects and indications of sacral surface therapeutic electrical stimulation (SS-TES) for refractory urinary incontinence.

Design: Evaluation before and after therapy.

Setting: On clinical site and at nursing home.

Subjects: Seven neurogenic bladder, five unstable bladder and six nocturia cases were investigated. Twelve were outpatients and six were residents.

Interventions: Surface electrodes were placed at the posterior sacral foramens of S2 and S4. Stimulation conditions were duration 0.3 ms, frequency 20 Hz and maximum intensity. The stimulation was continued for 15 min twice daily for over one month.

Main outcome measures: Therapeutic effects were evaluated on the basis of voiding charts as subjective findings and urodynamic study as objective findings before and after therapy.

Results: Subjective findings showed incontinence frequency significantly decreased from 2.39±1.4 times/day before therapy to 1.39±2.0 times/day after therapy (p≤0.01); 55.5% of patients were improved or greatly improved. Objective findings showed that maximum vesical capacity (MVC) significantly increased from 208.29±94.5 ml before therapy to 282.19±66.8 ml (p≤0.001). Uninhibited contraction significantly decreased from 40.4±31.4 cmH2O before therapy to 25.79±23.9 cmH2O (p≤0.01); 44% of patients were improved or greatly improved. This therapy was effective in particular for cases whose MVC was small before applying SS-TES.

Conclusion: SS-TES was effective in some patients with refractory urinary incontinence.
The effects of position on oxygen saturation in acute stroke: a systematic review
Authors: Tyson S F , Nightingale P
Published: November 2004

Objective: To investigate the effect of body position on oxygen saturation in the acute stages post stroke.

Design: Systematic review.

Methods: Databases: PREMEDLINE and MEDLINE, Psychinfo, EMBASE, CINAHL, PEDro, all EBM Reviews and Scottish Intercollegiate Guidelines Network (SIGN). Keywords: combinations of cerebrovascular accident/stroke/hemiplegia/ cerbrovascular disorders and position or posture or sitting or standing/lying/supine/ side lying, with oxygen saturation/oxygen levels/blood gas analysis/hypoxia/sleep apnea syndrome/obstructive sleep disorder/Cheyne Stokes breathing. Limits: English language, human, adults and clinical trials. The quality of relevant papers was independently reviewed using criteria based on the SIGN guidelines for randomized controlled trials and methods described by Rywdik et al.

Results: There were four relevant studies involving 183 patients: three high quality and one poor quality. Heterogeneity in the testing positions, selection criteria, outcome measures and analysis methods prevented meta-analysis. There was strong evidence that body position did not affect oxygen saturation in acute stroke patients without relevant (respiratory) co-morbidities. There was limited evidence that sitting in a chair had a beneficial effect and lying positions had a deleterious effect on oxygen saturation in acute stroke patients with respiratory co-morbidities.

Conclusions: Acute stroke patients without respiratory co-morbidities can adopt any body position, people with respiratory co-morbidities should be positioned as upright as possible.
Dynamic relocation of epigenetic chromatin markers reveals an active role of constitutive heterochromatin in the transition from proliferation to quiescence
Authors: Grigoryev Sergei A. , Nikitina Tatiana , Pehrson John R. , Singh Prim B. , Woodcock Christopher L.
Published: November 2004

Quiescent lymphocytes have small nuclei, filled with masses of facultative heterochromatin. Upon receiving mitogenic signals, these cells undergo nuclear enlargement, chromatin decondensation, the reactivation of cell proliferation, and changes in the intranuclear positioning of key genes. We examined the levels and intranuclear localization of major histone modifications and non-histone heterochromatin proteins in quiescent and reactivated mouse spleen lymphocytes. Dramatic and selective changes in localization of two heterochromatin-associated proteins, the histone variant macroH2A and HP1α occurred during lymphocyte reactivation. Reciprocal changes in the locations of these two proteins were observed in activated lymphocytes and cultured mouse fibroblasts induced into quiescence. We also describe a new apocentric nuclear compartment with a unique set of histone modifications that occurs as a zone of chromatin surrounding centromeric heterochromatin in differentiated lymphocytes. It is within this zone that the most significant changes occur in the transition from proliferation to quiescence. Our results suggest that constitutive centromeric heterochromatin plays an active role in cell differentiation and reactivation.
Presynaptic Cav2.1 and Cav2.2 Differentially Influence Release Dynamics at Hippocampal Excitatory Synapses
Authors: Scheuber Anita , Miles Richard , Poncer Jean Christophe
Published: November 2004

Presynaptic calcium influx at most excitatory central synapses is carried by both Cav2.1 and Cav2.2 channels. The kinetics and modulation of Cav2.1 and Cav2.2 channels differ and may affect presynaptic calcium influx. We compared release dynamics at CA3/CA1 synapses in rat hippocampus after selective blockade of either channel subtype and subsequent quantal content restoration. Selective blockade of Cav2.1 channels enhanced paired-pulse facilitation, whereas blockade of Cav2.2 channels decreased it. This effect was observed at short (50 msec) but not longer (500 msec) intervals and was maintained during prolonged bursts of presynaptic activity. It did not reflect differences in the distance of the channels from the calcium sensor. The suppression of this effect by preincubation with the Go/i-protein inhibitor pertussis toxin suggests instead that high-frequency stimulation relieves inhibition of Cav2.2 by Go/i, thereby increasing the number of available channels.
Dendrodendritic Electrical Synapses between Mammalian Retinal Ganglion Cells
Authors: Hidaka Soh , Akahori Yasushi , Kurosawa Yoshikazu
Published: November 2004

Electrical synapses between α-type ganglion cells were detected using combined techniques of dual patch-clamp recordings, intracellular labeling, electron microscopy, and channel subunit connexin immunocytochemistry in the albino rat retina. After intracellular injection of Neurobiotin into α-cells of inner (ON-center) and outer (OFF-center) ramifying types, measurement of tracer coupling resulted in a preferentially homologous occurrence among cells of the same morphological type (n= 19 of 24). In high-voltage as well as conventional electron microscopic analysis, direct dendrodendritic gap junctions (average size, 0.86 μm long) were present in contact sites between tracer-coupled α-cells. In simultaneous dual whole-cell recordings from pairs of neighboring α-cells, these cells generated TTX-sensitive sustained spiking against extrinsic current injection, and bidirectional electrical synapses (maximum coupling coefficient, 0.32) with symmetrical junction conductance (average, 1.35 nS) were observed in pairs with cells of the same morphological type. Precise temporal synchronization of spike activity (average time delay, 2.7 msec) was detected when depolarizing currents were simultaneously injected into the pairs. To address whether physiologically identified electrical synapses constitute gap junctional connectivity between cell pairs, identified neuronal connexin36 immunoreactivity was undertaken in Lucifer yellow-labeled cell pairs after patch-clamp recordings. All α-cells expressed connexin36, and confocal laser-scanning imaging demonstrated that connexin36 is primarily located at dendritic crossings between electrically coupled cells (seven sites in a pair, on average). These results give conclusive evidence for electrical synapses via dendrodendritic gap junctions involving connexin36 in α retinal ganglion cells of the same physiological type.
RACK1 and Brain-Derived Neurotrophic Factor: A Homeostatic Pathway That Regulates Alcohol Addiction
Authors: McGough Nancy N. H. , He Dao-Yao , Logrip Marian L. , Jeanblanc Jerome , Phamluong Khanhky , Luong Ken , Kharazia Viktor , Janak Patricia H. , Ron Dorit
Published: November 2004

Alcoholism is a devastating disease that manifests as uncontrolled drinking. Consumption of alcohol is regulated by neurochemical systems within specific neural circuits, but endogenous systems that may counteract and thus suppress the behavioral effects of ethanol intake are unknown. Here we demonstrate that BDNF plays a role in reducing the behavioral effects of ethanol, including consumption, in rodents. We found that decreasing the levels of BDNF leads to increased behavioral responses to ethanol, whereas increases in the levels of BDNF, mediated by the scaffolding protein RACK1, attenuate these behaviors. Interestingly, we found that acute exposure of neurons to ethanol leads to increased levels of BDNF mRNA via RACK1. Importantly, acute systemic administration of ethanol and voluntary ethanol consumption lead to increased levels of BDNF expression in the dorsal striatum. Taken together, these findings suggest that RACK1 and BDNF are part of a regulatory pathway that opposes adaptations that lead to the development of alcohol addiction.
Science and Philosophy: Comparison of Cognitive Therapy and Rational Emotive Behavior Therapy
Authors: Padesky Christine A. , Beck Aaron T.
Published: November 2004

Aaron T. Beck’s Cognitive Therapy (CT) and Albert Ellis’ Rational Emotive Behavior Therapy (REBT) are compared. A major difference between these therapies is that CT is an empirically based therapy and REBT is philosophically based. The origins and subsequent development of the therapies are reviewed with this difference highlighted. Comparisons between CT and REBT practice are made regarding attitudes toward client beliefs, use of guided discovery, types of cognition addressed, and the nature of the client-therapist relationship. The scientific foundations of CT are summarized in terms of the specificity of its conceptual models, the construction of targeted treatment protocols, and empirical findings that support both CT conceptualizations and treatments.
When Clients Are Untruthful: Implications for the Therapeutic Alliance, Case Conceptualization, and Intervention
Authors: Newman Cory F. , Strauss Jennifer L.
Published: November 2004

Therapists endeavor to be genuine and trustworthy with clients, thus facilitating the establishment and maintenance of a positive therapeutic relationship. Unfortunately, clients sometimes knowingly give false or misleading information, maintain counter therapeutic hidden agendas, and deliberately obscure clinically relevant facts. Such factors likely will obstruct the process of case conceptualization, strain the therapeutic relationship, and result in disagreements about proper interventions. We discuss some of the telltale signs of clients’ untruthfulness, and suggest ways in such cases for therapists to draw upon clients’ behaviors in session to construct useful case formulations. Additionally, we describe a number of interventions that increase the chances of pursuing healthy, appropriate, therapeutic goals, irrespective of clients’ degree of sincerity.
A Case of Multiple Chemical Sensitivities: Cognitive Therapy for Somatization Disorder and Metaworry
Authors: Temple Scott
Published: November 2004

“Multiple chemical sensitivities” has become an increasingly common clinical presentation to physicians, though it is infrequently seen by psychotherapists. This case report describes a 61-year-old woman who presents with a long history of chemical sensitivities, that led to a somatization disorder with debilitating agoraphobia, depression, and marital problems. Features of a variety of anxiety disorders are present, as are metacognitions that required an unusual case conceptualization. A cognitive therapy case conceptualization and treatment are described, which address the highly idiosyncratic clinical presentation of this patient.
Treatment Integrity Concerns in Cognitive Therapy for Depression
Authors: McGlinchey Joseph B. , Dobson Keith S.
Published: November 2004

With the emergence of manualized treatments in the 1980s, research protocols have focused increasing attention on documenting the integrity of treatment delivery. Two constructs have guided the conceptualization of assessing treatment integrity. The first, adherence, concerns the extent to which therapists adhere to the interventions of a therapy being tested, and measuring which particular interventions are performed. The second, competence, concerns the quality or skill in therapists’ execution of the therapy being tested. This article reviews the development of treatment integrity research for cognitive therapy in depression, and discusses salient issues that have arisen in its assessment. Recommendations for further refining the considerations of adherence and competence in the delivery of cognitive therapy are provided.
Developing and Testing of the Foot Care Confidence Scale
Authors: Sloan Helen L.
Published: November 2004

This study developed and tested the Foot Care Confidence Scale (FCCS), an instrument designed to measure the confidence (self-efficacy) diabetics have in performing foot self care. Content validity was assessed using Lynn’s (1986) Content Validity Index (CVI) with a total of 100% content validity (Sloan, 1993). The FCCS was administered to four persons with diabetes (Sloan, 1994) and pilot tested with 41 healthy older adults (Wills & Sloan, 1995). Based on the feedback from the pilot testing and CVI panel of judges, as well as additional literature review, the instrument was revised. A study involving 122 community-dwelling older adults with a diagnosis of diabetes for five or more years was conducted. The FCCS had a Cronbach’s alpha of 0.92. Factor analysis revealed that all 12 items loaded on one factor and all 12 items are needed to measure confidence to care for one’s feet. The FCCS is a practical instrument for use in many settings, especially where time constraints exist. It may assist the nurse in evaluating and improving outcomes of self care of the feet of persons with diabetes mellitus.
Temporal changes in mercury bioaccumulation by predatory fishes of boreal lakes following the invasion of an exotic forage fish
Authors: Johnston Thomas A. , Leggett William C. , Bodaly Richard A. , Swanson Heidi K.
Published: November 2004

We evaluated the prediction that mercury concentrations of predatory fishes in boreal lakes would rise following the invasion of an exotic forage fish species (rainbow smelt, Osmerus mordax) that was believed to feed at a higher trophic position than native forage fishes. We compared temporal trends (postinvasion minus preinvasion values) in fish mercury bioaccumulation between lakes experiencing recent smelt invasions and reference lakes of central Canada. Piscivore mercury concentrations in this region have remained stable or declined during approximately the last 20 years. These trends were not strongly influenced by the smelt invasion, despite the fact that smelt were a major prey item for all piscivore species examined. The effect of smelt invasion on mercury bioaccumulation in the predator species reflected the importance of smelt in their respective diets (lake trout, Salvelinus namaycush > walleye, Stizostedion vitreum > northern pike, Esox lucius). However, these effects were not statistically significant for any piscivore species. The impact of rainbow smelt invasion on mercury bioaccumulation in native piscivores of this region has been much less than previous food-web studies have predicted.
Field contamination of the starfish Asterias rubens by metals. Part 2: Effects on cellular immunity
Authors: Coteur Geoffroy , Gillan David , Joly Guillemette , Pernet Philippe , Dubois Philippe
Published: November 2004

To study the effects of matals on starfish in field conditions, immune responses measured in starfish from natural populations along a metal pollution gradient (long-term contamination) and in starfish that were transferred up the gradient (short-term contamination). Coelomic amoebocyte concentration (CAC) and production oh reactive oxygen species (ROS) by amoebocytes were measured in two varieties oh Asterias rubens occurring in the fjord: The black variety which lives only in the low salinity upper waters (22-26‰) and the red variety which live both in the upper layer and in the deeper layer characteruzed by a salinity close to that oh seawater (30‰). The studied immune response were stimulated in starfish living along the metal pollution gradient according to the contamination oh these starfish by cadmium. However, the sensitivity oh these responses toward metals appeared to be strongly modulated by the salinity stress. In red starfish living at 30‰ and transferred up the contamination gradient, the immune responses were inhibited and closely hollowed the short-term accumulation oh metals in the animal organs. Starfish transferred down the gradient did not recover normal immune responses in the short-term and appeared highly sensitive to caging stress. It is suggested that the impact oh metals on the immune responses oh A. rubens in field conditions occurs in three phases. Short-term inhibitory effects are exerted by a direct action of metals on the immune cells and are followed by a recovery due to the induction oh protective mechanisms. Eventually, when these mechanisms are overwhelmed by a long-term contamination, indirect and durable stimulatory effects on the immune responses appear due to a global disruption oh the animal physiology.
Comparison of the sensitivity of three nematode species to copper and their utility in aquatic and soil toxicity tests
Authors: Boyd Windy A. , Williams Phillip L.
Published: November 2004

Nematodes are useful organisms for aquatic and soil toxicity testing because of their abundance and diversity as well as their ease of culturing and maintenance in the laboratory. The nematode Caenorhabditis elegans has been used extensively in toxicity testing, but its sensitivity to metal exposures in relation to other nematodes remains unclear. In this study, we compare the sensitivity and ease of use of two other rhabditid nematodes, Panagrellus redivivus and Pristionchus pacificus, to C. elegans. Toxicity endpoints were chosen to investigate the effects of Cu on the survival of these nematodes after soil exposures and on the survival, reproduction, movement, and feeding behavior of nematodes after exposures in aquatic medium. In all lethality testing, P. pacificus was the most sensitive, C. elegans exhibited intermediate sensitivity, and P. redivivus was the least sensitive. Reproduction and movement of C. elegans and reproduction of P. pacificus were decreased 50% by similar concentrations of Cu (EC50s ∼2 mg/L), but P. pacificus movement was less sensitive to Cu exposures (EC50 = 8 mg/L). Although all nematodes may be useful in lethality assays, using P. redivivus in toxicity tests is complicated by the presence of two sexes and difficulties in obtaining age-synchronized cultures. Pristionchus pacificus is an ideal acute toxicity-testing organism because of its sensitivity and ease of culturing. However, C. elegans appears to be more sensitive and therefore most useful in behavioral assays. Future studies of the relative sensitivities of nematodes in toxicity testing should continue to investigate additional toxicants, nematode species, and quantifications of sublethal effects after soil exposures.
Coherent Control of Molecular Dynamics
Authors: Shapiro Moshe , Brumer Paul
Published: November 2004

We review theoretical work in the field of ‘Coherent Control’, whose essence is the use of quantum interferences between indistinguishable competing pathways to enhance one (chemical) product in preference to all others. We explain the principles of bichromatic and polychromatic control, pulse shaping, and the use of one‐ versus three‐photon interferences to control branching ratios. As an example of coherent control, we show how it may be used to convert racemic mixtures to samples containing the pure enantiomer of choice. We also show that the handedness of a molecular system is determined by the phase of incident light fields, thus highlighting a deep connection between the quantum mechanical phase, reflecting the spatiotemporal history of the combined light–matter system, and the handedness.
Definitionen von Grundbegriffen mit Bezug zu niedermolekularen und polymeren Flüssigkristallen
Authors: Tschierske Carsten , Pelzl Gerhard , Diele Siegmar
Published: November 2004

Dieses ist das erste von der IUPAC Commission on Macromolecular Nomenclature veröffentlichte Dokument zum Thema Flüssigkristalle. Wegen der Themenbreite wurde es in Zusammenarbeit mit der International Liquid Crystal Society erarbeitet. Es enthält Definitionen von Begriffen mit Bezug zu niedermolekularen und polymeren Flüssigkristallen und stützt sich auf grundlegende Definitionen, die bei der Beschreibung von Flüssigkristallen und in den Polymerwissenschaften weit verbreitet sind. Die Begriffe sind in fünf Abschnitte zusammengefasst: allgemeine Definitionen von flüssigkristallinen und mesomorphen Zuständen der Materie, Arten von Mesophasen, optische Texturen und Defekte von Flüssigkristallen, physikalische Charakteristika (einschließlich elektrooptischer und magnetooptischer Eigenschaften) von Flüssigkristallen und schließlich flüssigkristalline Polymere. Es wurden die Begriffe ausgewählt, die in der allgemein üblichen strukturellen, thermischen und elektrooptischen Beschreibung flüssigkristalliner Materialien häufig verwendet werden.
Laparoscopic skills training and assessment
Authors: Aggarwal R , Moorthy K , Darzi A
Published: November 2004

Background

The introduction of laparoscopic techniques to general surgery was associated with many unnecessary complications, which led to the development of skills laboratories to train novice laparoscopic surgeons. This article reviews the tools currently available for training and assessment in laparoscopic surgery.

Methods

Medline searches were performed to identify articles with combinations of the following key words: laparoscopy, training, curriculum, virtual reality and assessment. Further articles were obtained by manually searching the reference lists of identified papers.

Results

Current training involves the use of box trainers with either innate models or animal tissues; it lacks objective assessment of skill acquisition. Virtual reality simulators have the ability to teach laparoscopic psychomotor skills, and objective assessment is now possible using dexterity-based and video analysis systems.

Conclusion

The tools are now available for the development of a structured, competency-based, laparoscopic surgical training programme.
Surgical safety and overwork
Authors: Pfaff H
Published: November 2004

The article by Holger Pfaff of Cologne, Germany that follows is the ninth and final paper of the BJS series of leading articles on patient safety; in it he considers the problem of surgeons' often excessive workload. Those who would like to read the series as a whole should start with the April 2004 issue of the Journal. A trainees' viewpoint of safety issues has been considered along with safety lessions from the airlines. Infections, patient volume, the nature of adverse events and information technology have been highlighted in separate papers, and the importance of an evidence-based approach has been recognized on both sides of the Atlantic.