bluuebunny/crossref_metadata_2025 huggingface dataset:
Speract induces calcium oscillations in the sperm tail
Authors: Wood Chris D. , Darszon Alberto , Whitaker Michael
Published: April 2003

Sea urchin sperm motility is modulated by sperm-activating peptides. One such peptide, speract, induces changes in intracellular free calcium concentration ([Ca2+]i). High resolution imaging of single sperm reveals that speract-induced changes in [Ca2+]i have a complex spatiotemporal structure. [Ca2+]i increases arise in the tail as periodic oscillations; [Ca2+]i increases in the sperm head lag those in the tail and appear to result from the summation of the tail signal transduction events. The period depends on speract concentration. Infrequent spontaneous [Ca2+]i transients were also seen in the tail of unstimulated sperm, again with the head lagging the tail. Speract-induced fluctuations were sensitive to membrane potential and calcium channel blockers, and were potentiated by niflumic acid, an anion channel blocker. 3-isobutyl-1-methylxanthine, which potentiates the cGMP/cAMP-signaling pathways, abolished the [Ca2+]i fluctuations in the tail, leading to a very delayed and sustained [Ca2+]i increase in the head. These data point to a model in which a messenger generated periodically in the tail diffuses to the head. Sperm are highly polarized cells. Our results indicate that a clear understanding of the link between [Ca2+]i and sperm motility will only be gained by analysis of [Ca2+]i signals at the level of the single sperm.
GDNF promotes tubulogenesis of GFRα1-expressing MDCK cells by Src-mediated phosphorylation of Met receptor tyrosine kinase
Authors: Popsueva Anna , Poteryaev Dmitry , Arighi Elena , Meng Xiaojuan , Angers-Loustau Alexandre , Kaplan David , Saarma Mart , Sariola Hannu
Published: April 2003

Glial cell line–derived neurotrophic factor (GDNF) and hepatocyte growth factor (HGF) are multifunctional signaling molecules in embryogenesis. HGF binds to and activates Met receptor tyrosine kinase. The signaling receptor complex for GDNF typically includes both GDNF family receptor α1 (GFRα1) and Ret receptor tyrosine kinase. GDNF can also signal independently of Ret via GFRα1, although the mechanism has remained unclear. We now show that GDNF partially restores ureteric branching morphogenesis in ret-deficient mice with severe renal hypodysplasia. The mechanism of Ret-independent effect of GDNF was therefore studied by the MDCK cell model. In MDCK cells expressing GFRα1 but no Ret, GDNF stimulates branching but not chemotactic migration, whereas both branching and chemotaxis are promoted by GDNF in the cells coexpressing Ret and GFRα1, mimicking HGF/Met responses in wild-type MDCK cells. Indeed, GDNF induces Met phosphorylation in several ret-deficient/GFRα1-positive and GFRα1/Ret-coexpressing cell lines. However, GDNF does not immunoprecipite Met, making a direct interaction between GDNF and Met highly improbable. Met activation is mediated by Src family kinases. The GDNF-induced branching of MDCK cells requires Src activation, whereas the HGF-induced branching does not. Our data show a mechanism for the GDNF-induced branching morphogenesis in non-Ret signaling.
The strategic “pull” and operational “push” of total quality management in UK regional electricity service companies
Authors: McAdam Rodney , McLean John , Henderson Joan
Published: April 2003

The aim of this paper is to evaluate whether the UK regional electricity companies (RECs) has used total quality management (TQM) as a “push” or as a “pull” change methodology. “Push” is the operational improvement role of TQM; “pull” is the strategic or direction giving, improvement role of TQM. Following the onset of privatisation in 1990 there has been evidence of the RECs adopting TQM in both “push” and “pull” methodologies with varying degrees of success. An evaluation of the change processes involved will enable improved change models to be developed leading to increased business effectiveness in this £30 billion industry. Other possible benefits include the possible generalisations to other utilities such as water, roads, gas and telecoms. The research methodology includes a comparative case study analysis of five RECs, which have used TQM as their overarching approach to change. One of the cases is analysed to a more in‐depth level based on the multiple case findings. The findings indicate that the “push‐pull” analysis enables the full range of TQM activities to be evaluated in the RECs studied. Overall, there is a need to have a balanced portfolio of operational or “push”‐based TQM activity that is driven by strategic or “pull”‐based TQM planning and activity.
FINDING THE SIGN OF A FUNCTION VALUE BY BINARY CELLULAR AUTOMATON
Authors: CHAU H. F. , XU HAO , LEE K. M. , SIU L. W. , YAN K. K.
Published: April 2003

Given a continuous function f(x), suppose that the sign of f has only finitely many discontinuous points in the interval [0, 1]. We show how to use a sequence of one-dimensional deterministic binary cellular automata to determine the sign of f(ρ) where ρ is the (number) density of 1s in an arbitrarily given bit string of finite length provided that f satisfies certain technical conditions.
DISSIPATIVE TRIGONOMETRICALLY-FITTED METHODS FOR SECOND ORDER IVPs WITH OSCILLATING SOLUTION
Authors: SIMOS T. E.
Published: April 2003

In this paper a dissipative trigonometrically-fitted two-step explicit hybrid method is developed. This method is based on a dissipative explicit two-step method developed recently by Papageorgiou, Tsitouras and Famelis.6 Numerical examples show that the procedure of trigonometrical fitting is the only way in one to produce efficient dissipative methods for the numerical solution of second order initial value problems (IVPs) with oscillating solutions.
SIMULATION OF NATURAL CONVECTION IN A SQUARE CAVITY BY TAYLOR SERIES EXPANSION- AND LEAST SQUARES-BASED LATTICE BOLTZMANN METHOD
Authors: SHU C. , PENG Y. , CHEW Y. T.
Published: April 2003

The Taylor series expansion- and least squares-based lattice Boltzmann method (TLLBM) was used in this paper to extend the current thermal model to an arbitrary geometry so that it can be used to solve practical thermo-hydrodynamics in the incompressible limit. The new explicit method is based on the standard lattice Boltzmann method (LBM), Taylor series expansion and the least squares approach. The final formulation is an algebraic form and essentially has no limitation on the mesh structure and lattice model. Numerical simulations of natural convection in a square cavity on both uniform and nonuniform grids have been carried out. Favorable results were obtained and compared well with the benchmark data. It was found that, to get the same order of accuracy, the number of mesh points used on the nonuniform grid is much less than that used on the uniform grid.
MICROSCOPIC MODEL FOR THE LOGARITHMIC SIZE EFFECT ON THE CURIE POINT IN BARABÁSI–ALBERT NETWORKS
Authors: ALEKSIEJUK AGATA
Published: April 2003

We found that numbers of densely connected clusters in Barabási–Albert (BA) networks follow the exponential distribution. Heuristic arguments presented in the paper allow us to deduce that the critical temperature of the Ising model on the BA network is closely related to critical temperature of the largest densely connected cluster within the network. The arguments explain the logarithmic dependence of the critical temperature on the size of the network.
OPEN QUESTIONS IN HIGH ENERGY SPIN PHYSICS
Authors: JAFFE ROBERT L.
Published: April 2003

I describe a few of the most exciting open questions in high energy spin physics. After a brief look at (g - 2)μ and the muon electric dipole moment, I concentrate on QCD spin physics. Pressing questions include the interpretation of new asymmetries seen in semi-inclusive DIS, measuring the polarized gluon and quark transversity distributions in the nucleon, testing the DHGHY Sum Rule, measuring the orbital angular momentum in the nucleon, and many others which go beyond the space and time allotted for this talk.
NEUTRON SPIN STRUCTURE STUDY AT JEFFERSON LAB HALL A
Authors: CHEN JIAN-PING
Published: April 2003

With a high-intensity highly-polarized 6 GeV electron beam, and a high-density polarized 3 He target, we have carried out a number of experiments to study the neutron spin structure at Hall A in Jefferson Lab. Taking advantage of the high luminosity of Jefferson Lab, we completed two inclusive deep-inelastic-scattering experiments this summer. In the first precision measurements were made of the spin asymmetry [Formula: see text] in the valence quark (high Bjorken x) region, and in the second higher-twist effects were studied via precision measurements of [Formula: see text]. Physics motivation and preliminary results from the first experiment will be presented and discussed. I will also present nearly final results from an earlier experiment, which measured the generalized GDH sum for the neutron in the Q 2 range of 0.1 to 1 GeV 2. Planned near-term experiments will be briefly discussed.
SPIN STRUCTURE OF THE NUCLEON STUDIED BY HERMES
Authors:   on behalf of the HERMES Collaboration, SHIBATA TOSHI-AKI
Published: April 2003

The spin structure of the proton and neutron is studied by polarized deep inelastic scattering at HERMES. The longitudinally polarized electron beam at 27.6 GeV, polarized internal gas targets of 3 He , H and D, and a wide acceptance magnetic spectrometer with a particle identification capability are the important ingredients of the experiment. The basic concepts of the measurements at HERMES as well as recent physics results are presented.
DOUBLE SPIN ASYMMETRIES AND NUCLEON STRUCTURE AT CLAS
Authors:   The CLAS Collaboration, GRIFFIOEN KEITH
Published: April 2003

Inclusive and exclusive double spin asymmetries have been measured in Hall B at Jefferson Lab using the CLAS spectrometer. The data cover the resonance region for 0.15 < Q2 < 1.5 GeV 2. They were taken using longitudinally polarized electron beams of 2.6 and 4.3 GeV and longitudinally polarized 15 NH 3 and 15 ND 3 targets. The data provide information on the helicity amplitudes of specific resonances as well as on the Q2-evolution of the generalized Gerasimov-Drell-Hearn Sum Rule.
MEASUREMENT OF POLARIZED QUARK DISTRIBUTIONS AT HERMES
Authors:   on behalf of the HERMES Collaboration, BERNREUTHER STEFAN
Published: April 2003

The HERMES experiment has measured double spin asymmetries in the cross section for deep–inelastic scattering of longitudinally polarized positrons on longitudinally polarized 3 He (1995), 1 H (1996/97), and 2 D (1998) targets. A kinematic range of 0.023 < x < 0.6, and 1 GeV 2 < Q2 < 15 GeV 2 has been covered. From these asymmetries, based on inclusive and semi–inclusive measurements, polarized quark distributions are extracted as a function of x for up [Formula: see text] and down [Formula: see text] flavors as well as for valence and sea quarks. In the measured range, the up quark polarization is positive while the down quark polarization is negative. The sea quark polarization is compatible with zero. In this analysis all sea quark polarizations have been assumed to be flavor symmetric.

Presently HERMES is analyzing a high statistics 2 D data sample taken in 1999-2000. For these data it is possible to identify pions and kaons with a RICH detector which was installed in 1998. This will enable an extraction of the individual sea quark flavors [Formula: see text], [Formula: see text], and [Formula: see text] without any symmetry assumptions.
NUCLEON SPIN AND MAGNETIC MOMENT STRUCTURE
Authors: WANG FAN , CHEN X. S. , QING D. , ZONG H. S.
Published: April 2003

This talk reports the phenomenological model and the nonperturbative QCD studies of the nucleon spin and magnetic moment structure.
UNCERTAINTY OF POLARIZED PARTON DISTRIBUTIONS
Authors:   Asymmetry Analysis Collaboration, HIRAI M. , GOTO Y. , HORAGUCHI T. , KOBAYASHI H. , KUMANO S. , MIYAMA M. , SAITO N. , SHIBATA T.-A.
Published: April 2003

Polarized parton distribution functions are determined by a χ2 analysis of polarized deep inelastic experimental data. In this paper, uncertainty of obtained distribution functions is investigated by a Hessian method. We find that the uncertainty of the polarized gluon distribution is fairly large. Then, we estimate the gluon uncertainty by including the fake data which are generated from prompt photon process at RHIC. We observed that the uncertainty could be reduced with these data.
POLARIZED PARTON DISTRIBUTIONS AND THE POLARIZED GLUON ASYMMETRY
Authors: RAMSEY GORDON P.
Published: April 2003

The flavor-dependent valence, sea quark and antiquark spin distributions can be determined separately from theoretical assumptions and experimental data. We have determined the valence distributions using the Bjorken sum rule and have extracted polarized sea distributions, assuming that the quarks and anti-quarks for each flavor are symmetric. Other experiments have been proposed which will allow us to completely break the SU(3) symmetry of the sea flavors. To create a physical model for the polarized gluons, we investigate the gluon spin asymmetry in a proton, [Formula: see text]. By assuming that htis is is approximately Q2 invariant, we can completely determine the x-dependence of this asymmetry, which satisfies constituent counting rules and reproduces the basic results of the Bremsstrahlung model originated by Close and Sivers. This asymmetry can be combined with the measured unpolarized gluon density, G(x,Q2) to provide a prediction for ΔG(x,Q2). Existing and proposed experiments can test both the prediction of scale-invariance for AG(x,Q2) and the nature of ΔG itself. These models will be discussed along with suggestions for specific experiments which can be performed at energies typical of HERA, RHIC and LHC to determine the nature of these polarized distributions.
OVERVIEW OF LAMBDA AND HYPERON PHYSICS
Authors: SOFFER JACQUES
Published: April 2003

Some aspects of hyperon polarization phenomena in inclusive production in several high energy collision processes are reviewed. We concentrate on ways to achieve an accurate determination of the unpolarized and polarized fragmentation functions of a quark into a [Formula: see text]. A possible extension to the production of the other hyperons (Σ±,0, Ξ-,0), will be also briefly discussed.
SPIN EFFECTS IN HIGH ENERGY FRAGMENTATION PROCESSES
Authors: LIANG ZUO-TANG
Published: April 2003

Recent measurements, in particular those on Λ polarization and spin alignment of vector mesons in e+e-annihilation at LEP, and those on the azimuthal asymmetry at HERA, have attracted much attention on the spin effects in high energy fragmentation processes. In this talk, we make a brief introduction to the different topics studied in this connection and a short summary of the available data. After that, we present a short summary of the main theoretical results that we obtained in studying these different topics. The talk was mainly based on the publications [5-9] which have been finished in collaboration with C.Boros, Liu Chun-xiu and Xu Qing-hua.
RHIC ACCELERATOR ADVANCES FOR SPIN
Authors: BUNCE G.
Published: April 2003

Spin physics has always had tight coupling between the physics, both experiment and theory, and accelerator physics. We have all benefited from the tradition of this close collaboration. This workshop is focused on physics issues, and this talk discusses recent advances in the accelerator/polarimetry areas for the RHIC spin program. The first polarized proton collisions at RHIC (and in the world) are planned for this winter. (Since the writing occurs near the end of this first run with polarized proton collisions, our instant analysis of this very successful run is included in this written version.)
SEMI-INCLUSIVE HADRON PAIR PRODUCTION AND POLARIZED GLUONS IN THE PROTON
Authors: DONG YU-BING , MORII T. , YAMANISHI T.
Published: April 2003

To extract the polarized gluon distribution Δg, we study the large–pTlight hadron pair productions in polarized semi-inclusive reaction, which are dominantly produced via 2 mechanisms: photon–gluon fusion(PGF) and QCD Compton. The PGF gives us a direct information on Δg in the nucleon, whereas QCD Compton is background to the signal process for extracting Δg. By using symmetry relation among fragmentation functions and taking an appropriate combination of light hadron pair production processes, we can remove an effect of QCD Compton from those cross sections. Here we propose a new formula for extracting Δg from those processes.
NUCLEON SPIN PHYSICS USING CEBAF AT 11 GeV
Authors: MEZIANI ZEIN-EDDINE
Published: April 2003

We disscuss key experiments that address some of the nucleon spin physics questions as part of the 12 GeV planning for the energy upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. These experiments take advantage of a highly polarized beam and the availability of polarized target namely 3 He combined with a Medium Acceptance Spectrometer (MAD) in Hall A.
TRANSVERSITY DISTRIBUTION AND TENSOR CHARGE OF THE NUCLEON
Authors: HE HAN-XIN
Published: April 2003

We study the transversity distribution and the tensor charge of the nucleon based on the QCD sum rule approach. We also discuss the spin physics in the effective theory, and then analyse the quark contributions to the flavour-singlet axial charge and the tensor charge by means of the quark model. How to build a consistent nonperturbative approach for studying the spin physics and other hadronic physics at low-energy scale is also briefly introduced.
QUARK ORBITAL ANGULAR MOMENTUM AND GENERALIZED PARTON DISTRIBUTIONS
Authors: JI XIANGDONG
Published: April 2003

In this talk, I review the merit of introducing and measuring the quark orbital angular momentum contribution to the spin of the nucleon in the context of quantum chromodynamics.
EXCLUSIVE MESON AND PHOTON PRODUCTION AT HERMES
Authors:   for the HERMES Collaboration, BIANCHI NICOLA
Published: April 2003

First promising results for exclusive electroproduction of vector mesons, pseudoscalar mesons and real photons from HERMES are presented. Different observables like cross sections and single spin azimuthal asymmetries have been investigated. Results have been discussed within the recent formalism of the Generalized Parton Distributions.
TOP QUARK PAIR PRODUCTION AND DECAY INCLUDING SPIN EFFECTS AT HADRON COLLIDERS: PREDICTIONS AT NLO QCD
Authors: BERNREUTHER W. , BRANDENBURG A. , SI Z. G. , UWER P.
Published: April 2003

Top quark-antiquark [Formula: see text] pairs will be produced copiously at the Tevatron collider and in huge numbers at the LHC. This will make possible detailed investigations of the properties and interactions of this quark flavor. The analysis and interpretation of future data requires precise predictions of the hadronic production of [Formula: see text] pairs and of their subsequent decays. In this talk the reactions [Formula: see text], [Formula: see text] are considered and results are presented of our calculation6 of the dilepton angular distribution at next-to-leading order QCD, keeping the full dependence on the spins of the intermediate [Formula: see text] state. The angular distribution is determined for different choices of reference axes that can be identified with the t and [Formula: see text] spin axes. While the QCD corrections to the leading-order distribution turn out to be small in the case of the LHC, we find them to be sizeable in the case of the Tevatron and find, moreover, the angular distribution to be sensitive to the parton content of the proton.
STRANGE SEA ASYMMETRY IN NUCLEONS
Authors: LI XUE-QIAN , ZHANG XIAO-BING , MA BO-QIANG
Published: April 2003

We evaluate the medium effects in nucleon which can induce an asymmetry of the strange sea. The short-distance effects determined by the weak interaction can give rise to [Formula: see text] where [Formula: see text] is the medium-induced mass of strange quark by a few KeV at most, but the long-distance effects by strong interaction could be sizable.
PROPERTIES OF NUCLEONS AND NUCLEAR MATTER IN THE QUARK–DIQUARK MODEL AND EXTENSION TO FINITE DENSITY
Authors: BENTZ W. , MINEO H. , THOMAS A. W. , YAZAKI K.
Published: April 2003

We describe the nucleon as a quark-diquark bound state in a simple approximation to the full Faddeev method in the Nambu-Jona-Lasinio model. In the first part of this work, we concentrate on the role of axial vector diquark correlations for the static properties of the nucleon. In the second part, we construct an equation of state of nuclear matter based on the quark-diquark model for the single nucleon.
STRUCTURE FUNCTIONS OF THE NUCLEON IN THE QUARK–DIQUARK MODEL AND EXTENSION TO FINITE DENSITY
Authors: MINEO H. , BENTZ W. , YAZAKI K. , THOMAS A. W.
Published: April 2003

In this work we use a simple approximation to the relativistic Faddeev description of the nucleon in the framework of the Nambu-Jona-Lasinio (NJL) model. We discuss the flavor dependence of valence quark light-cone momentum distributions, and by comparing with the empirical informations we extract information on the strength of the axial vector diquark correlations. As an extension to finite density, we also discuss the EMC effect in nuclear matter, keeping only the scalar diquark channel in the wave function.
THE STUDY OF $e^+ e^-\to J/\psi \to N^* \bar N^*$ OR $\Lambda^* \bar \Lambda^*$
Authors: JI XIAOBIN , YANG HONGXUN
Published: April 2003

BES at BEPC is a good place to study baryon resonance. The process is e+e- → J/ψ, and then J/ψ decays to baryon pairs. In this paper we summarize recent results in this aspect from BES.
TWO-PHOTON COLLISIONS AT LEP
Authors: LI HSIANG-NAN
Published: April 2003

We study the effect of initial-state radiation in the double-tagged process ee → ee + hadrons by introducing the parton distribution functions associated with an electron, a positron, and a photon, which satisfy a set of Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations. It is observed that the radiation effect is not essential in most of the kinematic range. This observation applies to the subprocess of two-photon collision via quark exchange and via onium scattering. The deviation of the LEP data from the prediction for quark exchange at large rapidity may be regarded as a sign of new mechanism, such as the Balitskii-Fadin-Kuraev-Lipatov mechanism.
POLARIZED HEAVY BARYON DECAYS
Authors: CHOU CHUNG-HSIEN
Published: April 2003

We calculate the amplitudes involved in the heavy baryon nonleptonic decay Λb → ΛJ/ψ using perturbative QCD factorization theorem, which are expressed as convolutions of hard b quark decay amplitudes with the Λb baryon, Λ baryon and J/ψ meson distribution amplitudes. It is found that nonfactorizable contributions dominate over factorizable ones. Employing the distribution amplitudes determined in our previous works, we derive the branching ratio B(Λb → ΛJ/ψ) = (1.65 ~ 5.27) × 10-4 in agreement with data. We predict an asymmetry parameter α = -0.17 ~ -0.14 associated with the anisotropic angular distribution of the Λ baryons produced in polarized Λb baryon decays.
B MESON LIGHT-CONE DISTRIBUTION AMPLITUDES AND HEAVY-QUARK SYMMETRY
Authors: KAWAMURA HIROYUKI , KODAIRA JIRO , QIAO CONG-FENG , TANAKA KAZUHIRO
Published: April 2003

We present a systematic study of the B meson light-cone distribution amplitudes which are relevant for the QCD factorization approach for the exclusive B meson decays. We construct representations for the quark-antiquark distribution amplitudes in terms of independent dynamical degrees of freedom, which exactly satisfy the QCD equations of motion and constraints from heavy-quark symmetry.
ANGULAR DISTRIBUTION ANALYSIS OF B → J/ψ K* AND RESOLVING DISCRETE AMBIGUITIES IN THE DETERMINATION OF ϕ1
Authors: CHENG H.-Y. , KEUM Y.-Y. , YANG K.-C.
Published: April 2003

We discuss the angular distribution analysis of B → J/ψ K* decays and a way to resolve discrete ambiguites in the determination of the unitary triangle ϕ1(=β). We study the status of factorization hypothesis in the color-suppressed B meson decays: B → J/ψ K(*) within the general factorization approach and QCD-factorization method.
QUARK–ANTIQUARK ASYMMETRY OF THE NUCLEON STRANGE SEA
Authors: WAKAMATSU MASASHI
Published: April 2003

The possible asymmetry of the s- and [Formula: see text]-quark distributions in the nucleon is investigated on the basis of the flavor SU(3) chiral quark soliton model. We find that the asymmetry is much larger for the longitudinally polarized distribution functions than for the unpolarized ones. A preliminary comparison with the CCFR data for the unpolarized s-quark distribution and with the LSS fits of the longitudinally polarized distribution functions is encouraging.
A MODEL PREDICTION FOR POLARIZED ANTIQUARK FLAVOR ASYMMETRY
Authors: KUMANO S.
Published: April 2003

Polarized flavor asymmetry [Formula: see text] is investigated in a meson-cloud model. A polarized nucleon splits into a ρ meson and a baryon, then the polarized ρ meson interacts with the virtual photon. Because of the difference between the longitudinally polarized distributions [Formula: see text] and [Formula: see text] in ρ, the polarized flavor asymmetry is produced in the nucleon. In addition, we show that the g2 part of ρ contributes to the asymmetry especially at medium x with small Q2.
SYMMETRY BREAKING IN THE PARTON DISTRIBUTION FUNCTIONS OF THE NUCLEON
Authors: CAO FU-GUANG , SIGNAL A. I.
Published: April 2003

We study flavour symmetry breaking in the nucleon's parton distribution functions (PDF) using the meson cloud model and 'Pauli blocking' mechanism. It was found that the 'Pauli blocking' contribution to the integrated polarized asymmetry is much larger than the meson cloud, in contrast to approximate equality in the unpolarized case. We also investigate charge symmetry breaking in the nucleon's PDF using the meson cloud model. Our results are very different from the quark model calculations.
FLAVOR ASYMMETRY OF NUCLEON SEA FROM DETAILED BALANCE
Authors: ZHANG YONG-JUN , MA BO-QIANG , YANG LI-MING
Published: April 2003

In this study, the proton is taken as an ensemble of quark-gluon Fock states. Using the principle of detailed balance, we find [Formula: see text], which is in surprisingly agreement with the experimental observation.
CONSISTENT FACTORIZATION AND TWIST-3 CONTRIBUTIONS TO THE POLARIZED NUCLEON STRUCTURE FUNCTION g2(x,Q2)
Authors: YU HOI-LAI
Published: April 2003

Quark mass effects are clarified in the parton model approach to the transversely polarized nucleon structure function. The special propagator technique is employed to obtain manifestly gauge invariant results and extract the buried short-distance contributions inside the soft part after momentum factorization in the collinear expansion approach. A generalized massive special propagator for a massive quark is constructed. We identify the corresponding matrix elements of the transversely polarized structure function in deep inelastic scattering by the massive special propagator technique.
NUCLEAR EFFECTS IN SPIN STRUCTURE FUNCTION g1 OF 3He
Authors: GUZEY VADIM
Published: April 2003

Comprehensive analysis of nuclear effects relevant for DIS on polarized 3 He over a wide range of Bjorken x, 10-4 ≤ x ≤ 0.8, is presented.
POLARIZED HADRO- AND PHOTOPRODUCTION OF HEAVY QUARKS IN NLO QCD
Authors: BOJAK I.
Published: April 2003

We present the first calculation of the complete NLO QCD corrections to the production of heavy flavors with longitudinally polarized hadrons. This reaction can be used at RHIC to extract the gluon helicity density and may shed light on the "heavy quark enigma". The theoretical uncertainties are briefly discussed.
SPIN TRANSFER IN FRAGMENTATION PROCESSES AND HYPERON POLARIZATION IN DEEP-INELASTIC SCATTERING
Authors: LIU CHUN-XIU , XU QING-HUA , LIANG ZUO-TANG
Published: April 2003

We present the results for the polarizations of different octet hyperons produced in the current fragmentation regions of μ- N or νμ N deep-inelastic scatterings using different models for spin transfer in fragmentation processes. We found that measuring the polarization of Σ+ produced in these processes can give a good test to the validity of the different spin transfer models. Measuring PΣ+(T) in transversely polarized case should be able to give an useful check whether in high-energy fragmentation process the polarization transfer mechanisms are the same for both the longitudinally polarized and transversely polarized cases. A comparison with the existing data is made.
QUARKONIUM AT FINITE TEMPERATURE
Authors: CHAI HONG , IWASAKI MASAHARU
Published: April 2003

We study quarkonium at finite temperature by using a hadron string model. It is shown that as the temperature is increased, the mass of the quarkonium decreases and the slope of the Regge trajectory is changed.
INTRINSIC CHARM FLAVOR AND HELICITY CONTENT IN THE PROTON
Authors: SONG XIAOTONG
Published: April 2003

Contributions to the quark flavor and spin observables from the intrinsic charm in the proton are discussed in the SU(4) quark meson fluctuation model. Our results suggest that the probability of finding the intrinsic charm in the proton is less than 1%. The intrinsic charm helicity is small and negative, Δc ≃ -(0.003 ~ 0.015). The fraction of the total quark helicity carried by the intrinsic charm is less than 2%. A brief comparison of the quark flavor and spin observables with data and other models or analyses is given.
SOME QUESTIONS IN HIGH-ENERGY SPIN PHYSICS
Authors: HWANG W.-Y. PAUCHY
Published: April 2003

This is a write-up for the discussions which I chaired at the Closing Session. It preceded the two summary talks, the experimental summary by Jen-Chieh Peng and the theory one by Stanley Brodsky.
INFRARED SPECTRUM AND NONLINEAR OPTICAL PROPERTIES OF p-NITROANILINE-L-TARTARIC ACID (2:1) MOLECULAR COMPLEX
Authors: MARCHEWKA M. K. , RATAJCZAK H. , DEBRUS S.
Published: April 2003

The crystals of a new molecular complex, i.e. p-nitroaniline with L-tartaric acid were obtained by slow evaporation of an aqueous solution at room temperature. Room temperature powder infrared measurements were carried out. Tentative assignment for most bands was done. Very strong and broad absorption in the region of 3200–1800 cm-1 of infrared spectrum is observed. This notable vibrational effect suggests the presence of intense hydrogen-bonded network in the crystal structure of the complex. Second harmonic generation (SHG) efficiency d eff = 3.85 d eff (KDP). Some spectral features of this new crystal are referred to corresponding one for two other crystals comprising p-nitroaniline molecule i.e. p-nitroanilinium perchlorate and p-nitroanilinium-p-toluene-sulphonate.
Role of Nitric Oxide in the Regulation of Cerebral Blood Flow in Humans
Authors: Lavi Shahar , Egbarya Rania , Lavi Ronit , Jacob Giris
Published: April 2003

Background—

From animal studies it emerged that nitric oxide is important for the modulation of CO
2
-mediated cerebral blood flow (CBF chemoregulation) but not for the pressor-dependent mechanism (mechanoregulation). This hypothesis was tested in 18 healthy subjects.

Methods and Results—

Peak velocity (PV), diastolic velocity (DV), and mean velocity (MV) were measured by transcranial Doppler of the middle cerebral artery. Chemoregulation was assessed during normocapnia, hypocapnia, and after inhaled mixture of 95% O
2
+5% CO
2
. Mechanoregulation was evaluated by incremental doses of phenylephrine. Measurements were repeated during infusion of sodium nitroprusside (SNP). Regional cerebrovascular resistance (CVR) was calculated as mean blood pressure (BP)/MV. SNP infusion decreased mean BP by 7 mm Hg and CVR decreased from 1.38±0.08 to 1.29±0.09 mm Hg/cm · s
−1
;
P
=0.01, resulting in unaffected CBF. Phenylephrine (25 to 250 μg) caused a similar increase in BP in a dose-response fashion before and during SNP infusion. Despite the increments in BP and CVR, CBF remained unaffected. During hyperventilation (end-tidal CO
2
≈24 mm Hg), CVR increased by 75±3% and PV and DV decreased by 27±2% and 43±2%, respectively (
P
<0.001 for all). SNP infusion blunted the vasoconstrictive effect of hypocapnia; CVR increased only by 57±5%, and PV and DV decreased by 23±2% and 35±3%, respectively, (
P
<0.05 for all). Similarly, SNP augmented the vasodilatory effect of hypercapnia.

Conclusions—

Exogenous nitric oxide donor affects the basal cerebral vascular tone without affecting the CBF mechanoregulation. However, it selectively affects only the chemoregulatory mechanism (CO
2
-dependent). Thus, the CO
2
-NO axis is a cardinal pathway for CBF regulation in humans.
Atrial Ischemia Promotes Atrial Fibrillation in Dogs
Authors: Sinno Hani , Derakhchan Katayoun , Libersan Danielle , Merhi Yahye , Leung Tack Ki , Nattel Stanley
Published: April 2003

Background—

Coronary artery disease is a significant risk factor for atrial fibrillation (AF), but the basis for this association is incompletely understood. The present study evaluated the hypothesis that atrial ischemia can create a substrate for AF maintenance.

Methods and Results—

Atrial ischemia was induced by occlusion of an atrial arterial branch that did not provide blood flow to the ventricles. Atrial-arterial occlusion increased the duration of AF induced by burst pacing from 57±32 seconds (control) to 803±214 seconds (
P
<0.001) after 0.5 hour of occlusion and to 887±209 seconds (
P
<0.001) after 3 hours of occlusion. Prolonged AF (>20 minutes) was induced in 0 of 16 dogs (0%) under control conditions, 7 of 16 (44%,
P
<0.01) at 0.5 to 3 hours, and 5 of 13 (38%,
P
<0.01) 3 to 5 hours after occlusion. Atrial conduction was slowed substantially within the ischemic zone: eg, conduction delay was 8±1 ms at a cycle length of 200 ms, control, versus 22±5 ms (
P
<0.01) after 0.5 hours and 27±5 ms (
P
<0.001) after 3 hours of ischemia. Refractoriness was initially unaffected but was prolonged 5 hours after occlusion. Phase-delay analysis and high-density mapping confirmed severe conduction slowing in the ischemic zone. Histological examination confirmed the location of ischemic regions and revealed extensive ischemia-induced necrosis at sites of conduction delay.

Conclusions—

Experimental atrial ischemia creates a substrate for AF maintenance, apparently by causing local conduction slowing that promotes reentry. These results suggest that atrial ischemia may significantly promote AF, and may be relevant to AF mechanisms in association with coronary artery disease.
Increased Plasma Natriuretic Peptide Levels Reflect Symptom Onset in Aortic Stenosis
Authors: Gerber Ivor L. , Stewart Ralph A.H. , Legget Malcolm E. , West Teena M. , French Renelle L. , Sutton Timothy M. , Yandle Timothy G. , French John K. , Richards A. Mark , White Harvey D.
Published: April 2003

Background—

The onset of symptoms is a critical point in the natural history of aortic stenosis and the cardinal indication for valve replacement. This study assessed the associations between natriuretic peptide levels, disease severity, and cardiac symptoms in aortic stenosis.

Methods and Results—

Seventy-four patients with isolated aortic stenosis underwent independent assessment of symptoms, transthoracic echocardiography, and measurement of plasma levels of atrial natriuretic peptide, brain natriuretic peptide (BNP), and N-BNP. Natriuretic peptide levels were also measured in 100 clinically normal control subjects. The aortic valve area was smaller in symptomatic patients (n=45) than in asymptomatic patients (n=29; mean, 0.71±0.23 cm
2
and 0.99±0.31 cm
2
, respectively;
P
<0.0001). Plasma natriuretic peptide levels were higher in symptomatic patients than in asymptomatic patients (for N-BNP: median, 112 versus 33 pmol/L; interquartile range, 70 to 193 versus 16 to 58 pmol/L, respectively;
P
=0.0002). After adjustment for age, sex, serum creatinine, aortic valve area, and left ventricular ejection fraction, N-BNP levels were 1.74 times higher (95% confidence interval, 1.12 to 2.69) for symptomatic than asymptomatic patients with aortic stenosis (
P
=0.014). Natriuretic peptide levels increased with the New York Heart Association class (for N-BNP median values were 13, 34, 105, and 202 pmol/L for normal control subjects, class I, class II, and class III/IV patients, respectively; interquartile ranges for the same patients were 8 to 21, 16 to 58, 57 to 159, and 87 to 394 pmol/L;
P
<0.0001). Similar associations were observed for BNP and atrial natriuretic peptide.

Conclusions—

Plasma natriuretic peptide levels are elevated in symptomatic patients with aortic stenosis. Measurement of natriuretic peptides may complement clinical and echocardiographic evaluation of patients with aortic stenosis.
Twin-Twin Transfusion Syndrome
Authors: Gardiner Helena M. , Taylor Myles J.O. , Karatza Ageliki , Vanderheyden Tina , Huber Agnes , Greenwald Stephen E. , Fisk Nicholas M. , Hecher Kurt
Published: April 2003

Background—

In twin-twin transfusion syndrome (TTTS), the donor and recipient fetus are exposed to differing volume loads and show discordant intertwin vascular compliance in childhood despite identical genotype. We hypothesized that discordance is prevented by intrauterine endoscopic laser ablation of placental anastomoses, which abolishes intertwin transfusion. We tested this by examining pulse wave velocity (PWV) in brachial arteries of twin survivors of TTTS treated with and without laser therapy.

Methods and Results—

One hundred children (50 twin pairs, 27 with TTTS) were studied. Group 1 comprised 14 monochorionic (MC) twin pairs with TTTS treated symptomatically; group 2 comprised 13 MC twin pairs with TTTS treated by laser. The control groups comprised 12 MC twin pairs without TTTS (group 3) and 11 dichorionic twin pairs (group 4). Fetal cardiovascular data, predictive factors for, and duration of TTTS and cord blood were collected prospectively. We measured blood pressure and PWV photoplethysmographically at a median corrected postnatal age of 11 months (range, 1 week to 66 months). Both TTTS groups showed marked intertwin PWV discordance, unlike MCDA control subjects. The PWV discordance seen in laser treated twin pairs resembled that of dichorionic control subjects (heavier individual with higher PWV), whereas group 1 showed the opposite (negative) intertwin discordance (ANOVA
F
(1,45)=4.5,
P
=0.04). No significant differences in blood pressure or intrauterine growth were observed between TTTS groups.

Conclusions—

Vascular programming is evident in monozygotic twins with intertwin transfusion and is altered but not abolished by intrauterine therapy to resemble that seen in dichorionic twins.
Pacing-Induced Spontaneous Activity in Myocardial Sleeves of Pulmonary Veins After Treatment With Ryanodine
Authors: Honjo Haruo , Boyett Mark R. , Niwa Ryoko , Inada Shin , Yamamoto Mitsuru , Mitsui Kazuyuki , Horiuchi Toshiyuki , Shibata Nitaro , Kamiya Kaichiro , Kodama Itsuo
Published: April 2003

Background—

Recent clinical electrophysiology studies and successful results of radiofrequency catheter ablation therapy suggest that high-frequency focal activity in the pulmonary veins (PVs) plays important roles in the initiation and perpetuation of atrial fibrillation, but the mechanisms underlying the focal arrhythmogenic activity are not understood.

Methods and Results—

Extracellular potential mapping of rabbit right atrial preparations showed that ryanodine (2 μmol/L) caused a shift of the leading pacemaker from the sinoatrial node to an ectopic focus near the right PV-atrium junction. The transmembrane potential recorded from the isolated myocardial sleeve of the right PV showed typical atrial-type action potentials with a stable resting potential under control conditions. Treatment with ryanodine (0.5 to 2 μmol/L) resulted in a depolarization of the resting potential and a development of pacemaker depolarization. These changes were enhanced transiently after an increase in the pacing rate: a self-terminating burst of spontaneous action potentials (duration, 33.6±5.0 s; n=32) was induced by a train of rapid stimuli (3.3 Hz) applied after a brief rest period. The pacing-induced activity was attenuated by either depletion of the sarcoplasmic reticulum of Ca
2+
or blockade of the sarcolemmal Na
+
-Ca
2+
exchanger or Cl
−
channels and potentiated by β-adrenergic stimulation.

Conclusions—

PV myocardial sleeves have the potential to generate spontaneous activity, and such arrhythmogenic activity is uncovered by modulation of intracellular Ca
2+
dynamics.
Vasopeptidase Inhibitor Omapatrilat Induces Profound Insulin Sensitization and Increases Myocardial Glucose Uptake in Zucker Fatty Rats
Authors: Wang Chao-Hung , Leung Nathalie , Lapointe Nathalie , Szeto Linda , Uffelman Kristine D. , Giacca Adria , Rouleau Jean L. , Lewis Gary F.
Published: April 2003

Background—

ACE inhibitors (ACEIs) improve insulin resistance and prevent type 2 diabetes, possibly mediated by inhibition of bradykinin (BK) degradation. The vasopeptidase inhibitor omapatrilat (OMA) raises BK to a greater extent than ACEIs by dual enzyme inhibition, whereas its insulin-sensitizing effects and mechanisms have not been investigated.

Methods and Results—

We compared the insulin-sensitizing effects of OMA, ramipril (an ACEI), losartan (an angiotensin II type 1 receptor blocker), and placebo by 2-step euglycemic hyperinsulinemic clamp in insulin-resistant Zucker fatty rats (n=6 to 7 in each group). OMA resulted in a lower rate of endogenous glucose production than placebo at baseline (35±5 versus 54±4 mmol · kg
−1
· min
−1
,
P
<0.01), greater suppression of endogenous glucose production by low-dose insulin (73±11% versus 27±18%,
P
<0.05), and greater glucose disposal at high-dose insulin (135±5 versus 92±4 mmol · kg
−1
· min
−1
,
P
<0.01). Ramipril tended to improve insulin sensitivity, but losartan did not. OMA significantly increased 2-deoxyglucose uptake by myocardium, fat, and skeletal muscle. Ramipril increased 2-deoxyglucose uptake only by some skeletal muscles, but losartan did not. The insulin-sensitizing effects of OMA were blocked significantly by HOE-140 (a BK, B
2
receptor antagonist) and
N
G
-nitro-
l
-arginine methyl ester (a nitric oxide synthase inhibitor) in all tissues except myocardium.

Conclusions—

OMA induces profound insulin sensitization and increases myocardial glucose uptake in Zucker fatty rats. This effect is greater than that of ramipril and probably occurs at least in part via stimulation of the B
2
receptor. OMA has the potential for greater type 2 diabetes prevention than ACEI.
Ascorbic Acid Enhances Differentiation of Embryonic Stem Cells Into Cardiac Myocytes
Authors: Takahashi Tomosaburo , Lord Bernadette , Schulze P. Christian , Fryer Ryan M. , Sarang Satinder S. , Gullans Steven R. , Lee Richard T.
Published: April 2003

Background—

Embryonic stem (ES) cells are capable of self-renewal and differentiation into cellular derivatives of all 3 germ layers. In appropriate culture conditions, ES cells can differentiate into specialized cells, including cardiac myocytes, but the efficiency is typically low and the process is incompletely understood.

Methods and Results—

We evaluated a chemical library for its potential to induce cardiac differentiation of ES cells in the absence of embryoid body formation. Using ES cells stably transfected with cardiac-specific α-cardiac myosin heavy chain (MHC) promoter-driven enhanced green fluorescent protein (EGFP), 880 compounds approved for human use were screened for their ability to induce cardiac differentiation. Treatment with ascorbic acid, also known as vitamin C, markedly increased the number of EGFP-positive cells, which displayed spontaneous and rhythmic contractile activity and stained positively for sarcomeric myosin and α-actinin. Furthermore, ascorbic acid induced the expression of cardiac genes, including GATA4, α-MHC, and β-MHC in untransfected ES cells in a developmentally controlled manner. This effect of ascorbic acid on cardiac differentiation was not mimicked by the other antioxidants such as N-acetylcysteine, Tiron, or vitamin E.

Conclusions—

Ascorbic acid induces cardiac differentiation in ES cells. This study demonstrates the potential for chemically modifying the cardiac differentiation program of ES cells.
Sympathetic Nerve Activity in the Congenital Long-QT Syndrome
Authors: Shamsuzzaman Abu S.M. , Ackerman Michael J. , Kara Tomas , Lanfranchi Paola , Somers Virend K.
Published: April 2003

Background—

Patients with congenital long-QT syndrome (LQTS) are susceptible to life-threatening arrhythmias. The sympathetic nervous system may have an important triggering role for cardiovascular events in LQTS. We therefore examined measurements of sympathetic neural traffic in patients with LQTS and matched control subjects.

Methods and Results—

Twelve patients with congenital LQTS and 12 healthy volunteers matched for age, sex, and body mass index were studied. Heart rate, respiration, blood pressure, and sympathetic nerve activity to the skeletal muscle blood vessels (muscle sympathetic nerve activity) and to the skin (skin sympathetic nerve activity) were monitored and recorded continuously. Resting heart rate (
P
=
0.03), muscle sympathetic nerve activity burst rate (
P
=0.008), and burst incidence (
P
=0.02) were lower in patients with LQTS than in control subjects. However, skin sympathetic nerve activity was very similar in patients with LQTS and control subjects. Spectral analysis of RR variability showed a decreased low-frequency component, an increased high-frequency component, and a decrease in the ratio of the low-frequency component to the high-frequency component in patients with LQTS (
P
=0.01).

Conclusions—

LQTS is associated with a selective reduction in sympathetic drive to muscle blood vessels and perhaps also to the heart.
Evolution of Gravitational Synesthesia in Music: To Color and Light!
Authors: Galeyev Bulat M.
Published: April 2003

The author presents a detailed history and theory of a basic form of synesthesia, little studied to date, connected with the associative perception of gravity in music. This synesthesia appears to be common to all other kinds of art as well.
The Invented World of Mariano Taccola: Revisiting a Once-Famous Artist-Engineer of 15th-Century Italy
Authors: Fane Lawrence
Published: April 2003

The Sienese artist-engineer Mariano Taccola left behind five books of annotated drawings, presently in the collections of the state libraries of Florence and Munich. Taccola was well known in Siena, and his drawings were studied and copied by artists of the period, probably serving as models for Leonardo da Vinci's notebooks. However, his work has received little attention from scholars and students in recent times. The author, a sculptor, has long been interested in Taccola's drawings for his studio projects. Although Taccola lacked the fine drawing hand displayed by many of his contemporaries, his inventive work may appeal especially to viewers today. Based on examination of the original drawings, the author discusses the qualities that make Taccola's drawings unique and considers what Taccola's intentions may have been in making them.