bluuebunny/crossref_metadata_2025 huggingface dataset:
QUARK-MODEL INTERACTIONS FOR THE COMPLETE BARYON OCTET AND THEIR APPLICATIONS TO FEW-BARYON SYSTEMS
Authors: FUJIWARA Y. , KOHNO M. , SUZUKI Y. , NAKAMOTO C. , MIYAGAWA K. , NEMURA H.
Published: April 2003

Baryon-baryon interactions of the complete baryon octet (B8) are investigated in a unified framework of the (3q)-(3q) resonating-group method, which employs the spin-flavor SU6 quark-model wave functions. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon interaction. The characteristic features of the B8B8 interactions predicted by the most recent model fss2 are reviewed. The nucleon-nucleon sector of this SU6 quark model is applied to calculate properties of the three-nucleon bound state. The calculated binding energy for 3H is the closest to the experiment among many results obtained by detailed Faddeev calculations employing modern realistic nucleon-nucleon potentials.
FIRST EXPERIMENT TO PRODUCE Λ-HYPERNUCLEI USING ELECTRON BEAM AT JLAB
Authors:   FOR JEFFERSON LAB E89-009 COLLABORATION., TANG L.
Published: April 2003

The first experiment producing Λ-hypernuclear spectroscopy using the high-precision electron beam has been carried out at Jefferson Laboratory (JLab). A zero degree tagging technique for the scattered electrons was applied and the hypernuclear spectrometer system (HNSS) was successfully used to measure spectra from the (e, e′ K+) reaction. The best energy resolution obtained thus far in hypernuclear spectroscopy with magnetic spectrometers, near or below 1 MeV, was achieved. This paper describes the general technique of HNSS and the preliminary results for the [Formula: see text] and [Formula: see text] systems. A new phase of experiment on hypernuclear spectroscopy is approved for the future with much higher yield and quality and even better energy resolution.
LORENTZ BOOSTED NN POTENTIAL FOR FEW-BODY SYSTEMS: APPLICATION TO THE THREE-NUCLEON BOUND STATE
Authors: KAMADA H. , GLÖCKLE W. , GOLAK J. , ELSTER CH.
Published: April 2003

In the context of equal time relativistic quantum mechanics we introduce a Lorentz boosted potential. The dynamical input are nonrelativistic realistic nucleon-nucleon (NN) potentials, which by a suitable momentum change are analytically transformed into NN potentials fulfilling the relativistic two-nucleon Schrödinger equation in the c.m. system. The binding energy of the three nucleon (3N) bound state is calculated and we find that the boost effects for the two-body subsystems are repulsive and lower the binding energy. In addition we compare to a recently proposed approximate scheme.
NONMESONIC WEAK DECAYS OF SINGLE-Λ AND DOUBLE-Λ HYPERNUCLEI OF LIGHT MASS SYSTEMS
Authors: ITONAGA KAZUNORI , MOTOBA TOSHIO , UEDA TAMOTSU
Published: April 2003

The nucleon-induced and hyperon-induced nonmesonic weak decay rates of the single-Λ and double-Λ hypernuclei are evaluated in the meson-exchange potential model. The roles of K-meson exchange are discussed. The ΛΛ → nΛ decay rate of [Formula: see text] is estimated to be fair and might be detectable in a future experiment.
NONLOCALITY IN THE QUARK-MODEL INDUCED TWO-BARYON POTENTIAL
Authors: TAKEUCHI SACHIKO , SHIMIZU KIYOTAKA
Published: April 2003

Roles of the nonlocality in the two-baryon potential derived from the quark cluster model, especially in the one from the quark Pauli-blocking effect on the kinetic term, is investigated by employing the inverse scattering problem. This effect can be understood by changing the degrees of the mixing between the incoming wave and the 0ℓ state of the inter-baryon-cluster wave function; which can be expressed by a baryon potential with high nonlocality. We look into the properties of this nonlocal potential by comparing it to the on-shell equivalent local potential. Their off-shell behaviors are very different from each other in the channels where the Pauli-blocking effect is large. The off-shell behavior of the nonlocal potential, however, seems to be simulated well when we keep the nonlocality of the potential between the 0s state and the other states.
THREE-ALPHA STRUCTURES AND ALPHA-CONDENSATION IN 12C
Authors: KUROKAWA CHIE , KATŌ KIYOSHI
Published: April 2003

The 3α resonances in 12 C are investigated in a framework of the complex scaling method. Calculated resonance parameters well reproduce the experimental data and we can obtain the second 2+ state just above the third 0+ state.
RESONANCES AND CONTINUUMS IN THE THREE-BODY BREAKUP OF HALO NUCLEI WITH THE COMPLEX SCALING METHOD
Authors: MYO TAKAYUKI , KATŌ KIYOSHI , AOYAMA SHIGEYOSHI , IKEDA KIYOMI
Published: April 2003

We investigate the three-body Coulomb breakup reaction of two-neutron halo nuclei 11 Li , where we adopt the extended three-body model of 11 Li with paying attention to the pairing correlation of the nuclei, and also employ the complex scaling method (CSM) to solve the three-body unbound states of 11 Li . From the results, we cannot find any dipole resonances, at least, having small decay widths. This means that the breakup strength is exhausted by the continuum states. We compare the obtained strength showing the low energy enhancement to the several experimental data.
A THREE-BODY MODEL ON NEUTRON HALO IN EXOTIC LIGHT NUCLEI
Authors: REN ZHONGZHOU , LI NING , ZHANG H. Y. , SHEN W. Q.
Published: April 2003

The three-body calculations on halo nuclei are reviewed and discussed. It is concluded that the ground state properties of halo nuclei 11 Li , 14 Be and 17 B are independent of the shape of two-body potentials and an explanation on it is given. It is also shown that an introduction of a three-body interaction may be useful for a good explanation of the properties of halo nuclei.
COUPLED-CHANNEL STUDY FOR O-ISOTOPES WITH THE CORE PLUS VALENCE NEUTRONS MODEL
Authors: MASUI HIROSHI , MYO TAKAYUKI , KATŌ KIYOSHI , IKEDA KIYOMI
Published: April 2003

We study 17 O and 18 O nuclei by using the core +n(+n) model. We perform the coupled-channel and the resonating group method (RGM) calculations not only for bound states but also for resonant states of 17 O . We obtain the state dependent core-n folding potential and reasonable single-particle energy (SPE) in the 16 O core. By using the same interaction for 17 O , we study 18 O in the core +n+n system.
LASER-ELECTRON PHOTON PROJECT AT SPRING-8
Authors:   For the LEPS collaboration., NAKANO T.
Published: April 2003

The GeV photon beam at SPring-8 is produced by backward-Compton scattering of laser photons from 8 GeV electrons. Polarization of the photon beam will be ~100% at the maximum energy with fully polarized laser photons. We report the status of the new facility and the prospect of hadron physics study with this high quality beam. Preliminary results from the first physics run are presented.
DETAILED STUDY OF THE FEW NUCLEON SYSTEMS AT JEFFERSON LAB
Authors:   For the Jefferson Lab Hall A Collaboration., SAHA ARUN
Published: April 2003

In a new and detailed experimental program carried out at Jefferson Laboratory, the few nucleon systems has been studied via Electrodisintegration of Deuterium and the Helium nuclei. Interesting new results probing the high momentum structure have been studied via the (e,e'p) reaction using the two high resolution spectrometers in Hall A and various kinematic regions have been investigated. Detailed and precise information on the effective bound state momentum distributions have been measured for the first time up to missing momenta of 1 Gev/c in 3 He , exhibiting significant strength at these high momenta which the standard nuclear calculations fail to explain and could be an indication of the onset of non-nucleonic degrees of freedom. The continuum region in 3 He has also been investigated in great detail looking for nuclear correlations and quasi-deuteron strength. Response function separations have been carried out to extract details of the few body structure and relativistic dynamics. Measurements made so far on D and 4 He have focussed on specific kinematic regions and there are plans to extend them over kinematic ranges similar to the 3 He investigation.
ELECTROMAGNETIC EFFECTS AND THE LONG-STANDING THREE-NUCLEON ANALYZING POWER PUZZLE
Authors: TORNOW W. , NEIDEL E. M. , GONZÁLEZ TROTTER D. E. , HOWELL C. R. , CROWELL A. S. , MACRI R. A. , WALTER R. L. , WEISEL G. J. , ESTERLINE J. , WITAŁA H. , CROWE B. J. , PEDRONI R. S. , MARKOFF D. M.
Published: April 2003

New results for the neutron-deuteron analyzing power Ay(θ) at En = 1.2 and 1.9 MeV and their comparison to proton-deuteron data reveal a sizeable and unexpected difference which increases with decreasing center-of-mass energy. This finding calls for the theoretical treatment of a subtle electromagnetic effect presently not incorporated in rigorous three-nucleon scattering calculations, before it is justified to invoke charge-dependent three-nucleon forces and/or other new physics.
POLARIZATION MEASUREMENTS IN π0 PHOTOPRODUCTION FROM THE PROTON
Authors: GILMAN R.
Published: April 2003

In the resonance region, up to W ~ 2 GeV or so, π0 photoproduction probes resonance photoproduction, as well as non-resonant production processes. Above the resonance region, data are sparse, and it is not clear whether the reaction will be easier to understand with quark or with meson-baryon degrees of freedom. We have measured the proton recoil polarization for ten incident beam energies, across and above the resonance region. Despite the greatly extended kinematic range of the data, no approach to any existing quark-model prediction is seen.
ELECTROMAGNETIC K+ PRODUCTION ON LIGHT NUCLEI WITH BEAM AND HYPERON RECOIL POLARIZATIONS
Authors: MIYAGAWA K. , MART T. , BENNHOLD C. , GLÖCKLE W.
Published: April 2003

Kaon photo- and electroproduction processes on the deuteron are investigated theoretically. Modern hyperon-nucleon forces as well as an updated kaon production operator on the nucleon are used. Sizable effects of the hyperon-nucleon final state interaction are seen in various observables.
MEASUREMENT OF THE ANALYZING POWERS FOR THE ${\vec d}d \to {}^3{\rm He}\, n$ AND ${\vec d}d \to {}^3{\rm H}\, p$ REACTIONS AT INTERMEDIATE ENERGIES
Authors: SAITO T. , HATANO M. , KATO H. , MAEDA Y. , SAKAI H. , SAKODA S. , TAMII A. , UCHIGASHIMA N. , LADYGIN V. P. , ISUPOV A. YU. , LADYGINA N. B. , MALAKHOV A. I. , REZNIKOV S. G. , UESAKA T. , YAKO K. , OHNISHI T. , SAKAMOTO N. , SEKIGUCHI K. , KUMASAKA H. , NISHIKAWA J. , OKAMURA H. , SUDA K. , SUZUKI R.
Published: April 2003

Measurements of the tensor and vector analyzing powers Ayy, Axx, Axz, and Ay for the [Formula: see text] and [Formula: see text] reactions were performed at Ed = 270 and 200 MeV over wide angular range. T20 at θ cm = 0° and 180° were also measured at Ed = 270, 200, and 140 MeV. Obtained data were compared with predictions based on one nucleon exchange approximation.
THREE NUCLEON CORRELATIONS IN NUCLEAR MEDIUM
Authors: SONG H. Q. , BALDO M. , FIASCONARO A. , GIANSIRACUSA G. , LOMBARDO U.
Published: April 2003

The equation of state(EOS) of nuclear matter is studied up to the three-hole-line level of approximation in the Behte-Brueckner-Goldstone expansion. The results indicate a good convergence of the theory. The fact that the resulting EOS does not reproduce the empirical saturation point suggests that the three-body forces are most likely the main term missing in the nuclear Hamiltonian.
POLARIZATION TRANSFER MEASUREMENT FOR d-p ELASTIC SCATTERING: TO SEARCH FOR THREE NUCLEON FORCE EFFECTS
Authors: SEKIGUCHI K. , SAKAI H. , OKAMURA H. , TAMII A. , UESAKA T. , SUDA K. , SAKAMOTO N. , WAKASA T. , SATOU Y. , OHNISHI T. , YAKO K. , SAKODA S. , KATO H. , MAEDA Y. , HATANO M. , NISHIKAWA J. , SAITO T. , UCHIGASHIMA N. , KALANTAR-NAYESTANAKI N. , ERMISCH K.
Published: April 2003

Precise measurements of the deuteron to proton polarization transfer coefficients for the d-p elastic scattering have been made at 135 MeV/u at RIKEN Accelerator Research Facility. The obtained results are compared with the Faddeev calculations based on modern nucleon-nucleon forces together with Tucson-Melbourne Tucson-Melbourne' and Urbana–Argonne type of three nucleon forces.
RECENT RESULTS FROM BES J/ψ DATA
Authors:   For the BES collaboration., SHEN XIAOYAN
Published: April 2003

Recent preliminary results based on 5.8 × 107 J/ψ data, collected with BESII, are presented. These include Partial Wave Analyses (PWA) of [Formula: see text] and γπ+π-, the measurement of ηc mass, the search for interesting states, as well as the study of the excited baryon states.
QCD AND HADRON STRUCTURE
Authors: THOMAS ANTHONY W. , LEINWEBER DEREK B. , YOUNG ROSS D. , WRIGHT STEWART V.
Published: April 2003

There is considerable interest in the possibility of extracting model independent information on the masses and other properties of hadrons from lattice QCD, even though the state of the art involves light quark masses considerably higher than those found in nature. We review the applicability of effective field theory to this problem. Taking the rho meson as an example, we show that conventional, dimensionally regularized field theory is not sufficiently convergent to provide a reliable method of extrapolation. The reason for the poor convergence is discussed, along with the solution which this suggests. Finally we outline a very interesting suggestion of a connection between hadron masses in full and quenched QCD, using the nucleon and delta as examples.
THE CHIRAL LIMIT K → ππ MATRIX ELEMENTS OF THE ELECTROWEAK PENGUIN OPERATORS Q7,8
Authors: MALTMAN K. , CIRIGLIANO V. , DONOGHUE J. F. , GOLOWICH E.
Published: April 2003

The SU(3) chiral limit K → ππ matrix elements of the electroweak penguin operators, Q7,8, are determined using hadronic τ decay data, and dispersive and finite energy sum rules.
e+ e- ANNIHILATION INTO $\overline{N}N$ PAIRS
Authors: YAN Y. , KOBDAJ C. , UCHAI W. , FAESSLER AMAND , GUTSCHE T. , ZHENG Y. M.
Published: April 2003

The reactions of electron-position annihilation into nucleon-antinucleon pairs have been studied in a nonperturbative quark model. The work suggests that the two-step process, in which the primary [Formula: see text] pair forms first a meson and then the meson decays into baryon pair, is dominant over the one-step process in which the primary [Formula: see text] pair is directly dressed by two additional [Formula: see text] pairs to form a baryon pair. The experimental data indicates that there exists a vector meson with quantum numbers IG(JPC) = 0-(1--) and a mass around 2 GeV.
CONTROLLED ATOM-MOLECULE INTERACTIONS IN ULTRACOLD GASES
Authors: CHIN CHENG , KERMAN ANDREW J. , VULETIĆ VLADAN , CHU STEVEN
Published: April 2003

We observe and study the dynamic formation of cold Cs 2 molecules near collision Feshbach resonances in a cold cesium sample. The resonance Iinewidth is as low as E/h = 5 kHz , or equivalently, 10-11 eV. We suggest that few-atom, interaction effects can be studied in a 3D optical lattice where several atoms can be confined and isolated in an optical cell, which allows exquisite control of the atomic density and the interaction cross section.
SEARCH FOR SUPER-NARROW DIBARYON RESONANCES BY THE pd → pdX AND pd → ppX REACTIONS
Authors: TAMII A. , HATANO M. , KATO H. , MAEDA Y. , SAITO T. , SAKAI H. , SAKODA S. , UCHIGASHIMA N. , HATANAKA K. , HIROOKA D. , KAMIYA J. , WAKASA T. , YAKO K. , SEKIGUCHI K. , UESAKA T.
Published: April 2003

Dibaryons which have a very narrow decay width, called super-narrow dibaryons, are searched for by the p+d scattering at Ep = 295 MeV . The experiment was carried out at the Research Center for Nuclear Physics employing a two-arm magnetic spectrometer. A good mass resolution of 0.95 MeV and background free condition have been achieved. No resonance has been observed in the mass region of 1896–1914 MeV. The upper limits of the dibaryon production cross section have been determined.
SEARCH FOR SPACE STAR ANOMALY IN pd BREAKUP REACTION AT 13MeV
Authors: ISHIDA T. , YAGITA T. , OCHI S. , NOZOE S. , TSURUTA K. , NAKAMURA F. , SCHIECK H. G. P. G. , SAGARA K.
Published: April 2003

Systematic measurement of D(p,pp)n cross section has been made at an incident energy of 13MeV around the space star configuration. In spite of the anomaly found in nd breakup cross section, no anomaly has been found in pd breakup.
MEASUREMENT OF p+d ELASTIC SCATTERING AT EP = 392 MEV
Authors: TAMII A. , UCHIGASHIMA N. , SAKAI H. , HATANO M. , MAEDA Y. , SAITO T. , ISHIDA T. , KUBOKI H. , HATANAKA K. , WAKASA T. , KAMIYA J. , SHIMIZU Y. , KITAMURA Y. , OKAMURA H. , SUDA K. , YAKO K. , SEKIGUCHI K. , SATOU Y.
Published: April 2003

The cross sections and spin observables of the p+d elastic scattering have been measured at 392 MeV. The results are compared with the results of Faddeev calculations with and without including the three nucleon force.
PHASE-SHIFT ANALYSIS OF p-3He SCATTERING BELOW 200 MEV
Authors: YOSHINO HIRO , HARADA KAZUO , MATSUDA MASANORI , NAGATA JUNICHI
Published: April 2003

Phase-shift analyses of p-3 He below 200 MeV are summarized. The analysis at 30 MeV is newly performed at this time. The experiment is proposed in order to more precisely determine the phase-shift solution below 200 MeV.
THE PROTON-DEUTERON BREAK-UP PROCESS IN A THREE-DIMENSIONAL APPROACH
Authors: FACHRUDDIN IMAM , ELSTER CHARLOTTE , GLÖCKLE WALTER
Published: April 2003

The pd break-up amplitude in the Faddeev scheme is calculated by employing a three-dimensional method without partial wave decomposition (PWD). In the first step and in view of higher energies only the leading term is evaluated and this for the process d(p,n)pp. A comparison with the results based on PWD reveals discrepancies in the cross section around 200 MeV. This indicates the onset of a limitation of the partial wave scheme. Also around 200 MeV relativistic effects are clearly visible and the use of relativistic kinematics shifts the cross section peak to where the experimental peak is located. The theoretical peak height, however, is wrong and calls first of all for the inclusion of rescattering terms, which are shown to be important in a nonrelativistic full Faddeev calculation in PWD.
A SINGLE-PASS APPROACH TO ADAPTIVE SIMPLIFICATION OF OUT-OF-CORE MODELS
Authors: CAI KANGYING , WANG WENCHENG , FEI GUANGZHENG , WU ENHUA
Published: April 2003

The algorithm efficiency of existing adaptable out-of-core simplification algorithms is relatively low because these methods often require scanning the original model over one time. In this paper, we present an adaptive clustering method, known as the Balanced Tiling (BT) method, for out-of-core simplification which only needs one pass over the input model. The key idea behind BT is that the model surface can be recorded in a memory efficient manner using surface coding and the global distribution of surface details can be obtained through quadric quantizing of the original model. Besides the feature edge areas, our algorithm can position the corner areas, which are not noticed by some other out-of-core simplification approaches such as the Fei's BR algorithm, by analyzing the Garland's quadric error matrix. Based on this analysis, adaptive clustering is achieved by restoring detail areas with cluster split operations while further simplifying smooth areas with edge collapse operations. BT is especially suitable for handling super huge meshes because the I/O time is greatly reduced. BT produces high quality approximations and the memory requirement is small, being only related with the size of the output model.
FOOTPRINT SAMPLING-BASED MOTION EDITING
Authors: XU WEIWEI , PAN ZHIGENG , ZHANG MINGMIN
Published: April 2003

In this paper, we present a motion editing algorithm for the human biped locomotion captured by a motion capturing device. Our algorithm adopts footprints to describe the space-time constraints which should be satisfied during biped locomotion. The footprints are also used as an interface to enable the user to control the space-time constraints directly. A real-time Inverse Kinematics (IK) solver is adapted to compute the configuration of the human body and motion displacement mapping is then constructed using hierarchical B-spline. In order to facilitate the IK solver, we propose a sampling-based scheme to generate root trajectory. Hermit interpolation is then employed to generate the whole root trajectory. This scheme provides a speedup to root trajectory generation. The performance of our algorithm is further enhanced by the real-time IK solver, which directly computes the displacement angles as solution.
NON-RIGID BODY INTERPOLATION BASED ON GENERALIZED MORPHOLOGIC MORPHING
Authors: LIU WENYU , LI HUA , ZHU GUANGXI
Published: April 2003

This paper presents a new technique for non-rigid body interpolation based on generalized morphologic morphing. Non-rigid body interpolation can be divided into non-rigid body metamorphosis and local rigid body rotation. By constructing mappings between the two convex subsets, this approach can solve the metamorphosis problem of two non-homotopic objects. Based on the model of the normal vector sphere for polyhedrons, a fast morphologic summation algorithm for two convex polyhedrons is also proposed; this method avoids much excrescent computation and is faster than most classical implementation. This paper provides the proof of the principle of metamorphosis and discusses the different results of the metamorphosis process for the different objects. It is shown through the experiments that this approach can be applied to automatic font composition and interpolation between two key-frames in 3D computer animation as well as in many other practical applications.
OPTIMIZATION TECHNIQUES FOR ASSEMBLY PLANNING OF COMPLEX MODELS IN LARGE-SCALE VIRTUAL ENVIRONMENTS
Authors: WAN HUAGEN , GAO SHUMING , PENG QUNSHENG , CAI YIYU
Published: April 2003

Evaluation and planning of assembly processes in virtual environments, especially large-scale virtual environments, have attracted much attention in the engineering community. However, the planning of complex assemblies in virtual environments is still hindered by limitations like insufficient frame rates, unnatural user interaction, as well as deficiencies in the processing of assembly constraints. This paper discusses some optimization techniques for the assembly planning of complex assemblies in a large-scale virtual environment such as CAVE. Specifically, the real-time display of complex assemblies, the natural and intuitive assembly operations, and a real-time collision detection algorithm for the assembly applications are presented.
RAPTOR: OPTIMAL PROTEIN THREADING BY LINEAR PROGRAMMING
Authors: XU JINBO , LI MING , KIM DONGSUP , XU YING
Published: April 2003

This paper presents a novel linear programming approach to do protein 3-dimensional (3D) structure prediction via threading. Based on the contact map graph of the protein 3D structure template, the protein threading problem is formulated as a large scale integer programming (IP) problem. The IP formulation is then relaxed to a linear programming (LP) problem, and then solved by the canonical branch-and-bound method. The final solution is globally optimal with respect to energy functions. In particular, our energy function includes pairwise interaction preferences and allowing variable gaps which are two key factors in making the protein threading problem NP-hard. A surprising result is that, most of the time, the relaxed linear programs generate integral solutions directly. Our algorithm has been implemented as a software package RAPTOR–RApid Protein Threading by Operation Research technique. Large scale benchmark test for fold recognition shows that RAPTOR ignificantly outperforms other programs at the fold similarity level. The CAFASP3 evaluation, a blind and public test by the protein structure prediction community, ranks RAPTOR as top 1, among individual prediction servers, in terms of the recognition capability and alignment accuracy for Fold Recognition (FR) family targets. RAPTOR also performs very well in recognizing the hard Homology Modeling (HM) targets. RAPTOR was implemented at the University of Waterloo and it can be accessed at .
TWO NOTES ON GENOME REARRANGEMENT
Authors: OZERY-FLATO MICHAL , SHAMIR RON
Published: April 2003

A central problem in genome rearrangement is finding a most parsimonious rearrangement scenario using certain rearrangement operations. An important problem of this type is sorting a signed genome by reversals and translocations (SBRT). Hannenhalli and Pevzner presented a duality theorem for SBRT which leads to a polynomial time algorithm for sorting a multi-chromosomal genome using a minimum number of reversals and translocations. However, there is one case for which their theorem and algorithm fail. We describe that case and suggest a correction to the theorem and the polynomial algorithm.

The solution of SBRT uses a reduction to the problem of sorting a signed permutation by reversals (SBR). The best extant algorithms for SBR require quadratic time. The common approach to solve SBR is by finding a safe reversal using the overlap graph or the interleaving graph of a permutation. We describe a family of signed permutations which proves a quadratic lower bound on the number of affected vertices in the overlap/interleaving graph during any optimal sorting scenario. This implies, in particular, an Ω(n3) lower bound for Bergeron's algorithm.
EFFICIENT INFERENCE OF HAPLOTYPES FROM GENOTYPES ON A PEDIGREE
Authors: LI JING , JIANG TAO
Published: April 2003

We study haplotype reconstruction under the Mendelian law of inheritance and the minimum recombination principle on pedigree data. We prove that the problem of finding a minimum-recombinant haplotype configuration (MRHC) is in general NP-hard. This is the first complexity result concerning the problem to our knowledge. An iterative algorithm based on blocks of consecutive resolved marker loci (called block-extension) is proposed. It is very efficient and can be used for large pedigrees with a large number of markers, especially for those data sets requiring few recombinants (or recombination events). A polynomial-time exact algorithm for haplotype reconstruction without recombinants is also presented. This algorithm first identifies all the necessary constraints based on the Mendelian law and the zero recombinant assumption, and represents them using a system of linear equations over the cyclic group Z2. By using a simple method based on Gaussian elimination, we could obtain all possible feasible haplotype configurations. A C++ implementation of the block-extension algorithm, called PedPhase, has been tested on both simulated data and real data. The results show that the program performs very well on both types of data and will be useful for large scale haplotype inference projects.
BIOINFORMATICS MEETS PROTEOMICS — BRIDGING THE GAP BETWEEN MASS SPECTROMETRY DATA ANALYSIS AND CELL BIOLOGY
Authors: KEARNEY P. , THIBAULT P.
Published: April 2003

Proteomics research programs typically comprise the identification of protein content of any given cell, their isoforms, splice variants, post-translational modifications, interacting partners and higher-order complexes under different conditions. These studies present significant analytical challenges owing to the high proteome complexity and the low abundance of the corresponding proteins, which often requires highly sensitive and resolving techniques. Mass spectrometry plays an important role in proteomics and has become an indispensable tool for molecular and cellular biology. However, the analysis of mass spectrometry data can be a daunting task in view of the complexity of the information to decipher, the accuracy and dynamic range of quantitative analysis, the availability of appropriate bioinformatics software and the overwhelming size of data files. The past ten years have witnessed significant technological advances in mass spectrometry-based proteomics and synergy with bioinformatics is vital to fulfill the expectations of biological discovery programs. We present here the technological capabilities of mass spectrometry and bioinformatics for mining the cellular proteome in the context of discovery programs aimed at trace-level protein identification and expression from microgram amounts of protein extracts from human tissues.
Frequency Response of the Renal Vasculature in Congestive Heart Failure
Authors: DiBona Gerald F. , Sawin Linda L.
Published: April 2003

Background—

The renal vasoconstrictor response to renal nerve stimulation is greater in congestive heart failure (CHF) rats than in control rats. This study tested the hypothesis that the enhanced renal vasoconstrictor response to renal nerve stimulation in CHF is a result of an impairment in the low-pass filter function of the renal vasculature.

Methods and Results—

In response to conventional graded-frequency renal nerve stimulation, the reductions in renal blood flow at each stimulation frequency were greater in CHF rats than control rats. A pseudorandom binary sequence pattern of renal nerve stimulation was used to examine the frequency response of the renal vasculature. Although this did not affect the renal blood flow power spectrum in control rats, there was a 10-fold increase in renal blood flow power over the frequency range of 0.01 to 1.0 Hz in CHF rats. On analysis of transfer function gain, attenuation of the renal nerve stimulation input signal was similar in control and CHF rats over the frequency range of 0.001 to 0.1 Hz. However, over the frequency range of 0.1 to 1.0 Hz, although there was progressive attenuation of the input signal (−30 to −70 dB) in control rats, CHF rats exhibited a flat gain response (−20 dB) without progressive attenuation.

Conclusions—

The enhanced renal vasoconstrictor response to renal nerve stimulation in CHF rats is caused by an alteration in the low-pass filter function of the renal vasculature, resulting in a greater transfer of input signals into renal blood flow in the 0.1 to 1.0 Hz range.
Time Course of Stent Endothelialization After Intravascular Radiation Therapy in Rabbit Iliac Arteries
Authors: Cheneau Edouard , John Michael C. , Fournadjiev Jana , Chan Rosanna C. , Kim Han-Soo , Leborgne Laurent , Pakala Rajbabu , Yazdi Hamid , Ajani Andrew E. , Virmani Renu , Waksman Ron
Published: April 2003

Background—

Late total occlusion after vascular brachytherapy (VBT) continues to be a serious complication. Delayed reendothelialization was suggested as a pivotal cause, but the time course for complete healing is unknown.

Methods and Results—

Seventy-two rabbit iliac arteries underwent stent implantation and were treated with γ-radiation using
192
Ir. The prescribed doses were 0 Gy (controls, n=24 arteries), 15 Gy (n=24), or 30 Gy (n=24) at 2 mm. Animals were killed at 1 month (n=24), 3 months (n=24), or 6 months (n=24) and were analyzed for histomorphometry or scanning electron microscopy. Intimal area was reduced after VBT at 3 months with 15 and 30 Gy (0.66±0.07 and 0.66±0.04 mm
2
, respectively) compared with controls (1.01±0.11 mm
2
,
P
<0.05) and at 6 months with 30 Gy (0.75±0.09 versus 1.28±0.26 mm
2
in controls,
P
<0.01). Intimal area was similar at 6 months between 15 Gy and controls. At 1 month, 92±4% of the control stented segment was covered with endothelial cells, whereas only 37±4% and 37±8% was covered in the 15- and 30-Gy arteries, respectively. Similarly, at 3 and 6 months, there was a difference in the extent of reendothelialized areas (at 3 months, 95±2%, 32±12%, and 29±13%; and at 6 months, 98±2%, 40±8%, and 35±12% in control, 15-Gy, and 30-Gy arteries, respectively). Excess platelets and leukocytes were seen in irradiated arteries without complete coverage of endothelium.

Conclusions—

Reendothelialization after VBT is not completed at 6 months after VBT. Special care with prolonged antiplatelet therapy should be considered beyond that time point.
Assessment of the Tissue Distribution of Transplanted Human Endothelial Progenitor Cells by Radioactive Labeling
Authors: Aicher Alexandra , Brenner Winfried , Zuhayra Maaz , Badorff Cornel , Massoudi Schirin , Assmus Birgit , Eckey Thomas , Henze Eberhard , Zeiher Andreas M. , Dimmeler Stefanie
Published: April 2003

Background—

Transplantation of endothelial progenitor cells (EPCs) improves vascularization and left ventricular function after experimental myocardial ischemia. However, tissue distribution of transplanted EPCs has not yet been monitored in living animals. Therefore, we tested whether radioactive labeling allows us to detect injected EPCs.

Methods and Results—

Human EPCs were isolated from peripheral blood, characterized by expression of endothelial marker proteins, and radioactively labeled with [
111
In]indium oxine. EPCs (10
6
) were injected in athymic nude rats 24 hours after myocardial infarction (n=8) or sham operation (n=8). Scintigraphic images were acquired after 1, 24, 48, and 96 hours after EPC injection. Animals were then killed, and specific radioactivity was measured in different tissues. At 24 to 96 hours after intravenous injection of EPCs, ≈70% of the radioactivity was localized in the spleen and liver, with only ≈1% of the radioactivity identified in the heart of sham-operated animals. After myocardial infarction, the heart-to-muscle radioactivity ratio increased significantly, from 1.02±0.19 in sham-operated animals to 2.03±0.37 after intravenous administration of EPCs. Injection of EPCs into the left ventricular cavity increased this ratio profoundly, from 2.69±1.54 in sham-operated animals to 4.70±1.55 (
P
<0.05) in rats with myocardial infarction. Immunostaining of cryosections from infarcted hearts confirmed that EPCs homed predominantly to the infarct border zone.

Conclusions—

Although only a small proportion of radiolabeled EPCs are detected in nonischemic myocardium, myocardial infarction increases homing of transplanted EPCs in vivo profoundly. Radiolabeling might eventually provide an useful tool for monitoring the fate of transplanted progenitor cells and for clinical cell therapy.
Differences in the Bioenergetic Response of the Isolated Perfused Rat Heart to Selective β
1
- and β
2
-Adrenergic Receptor Stimulation
Authors: McConville Patrick , Fishbein Kenneth W. , Lakatta Edward G. , Spencer Richard G.S.
Published: April 2003

Background—

In the heart, striking functional differences exist after stimulation of the β
1
- and β
2
-adrenergic receptor (AR) subtypes. These may be linked to differences in metabolic response during β
1
- and β
2
-AR stimulation.

Methods and Results—

The relation between work and metabolism was examined during selective β
1
- and β
2
-AR stimulation (β
1
and β
2
groups, respectively) in the isolated perfused rat heart. Measurements were made of rate-pressure product (RPP=LV developed pressure × heart rate), phosphorus-containing metabolites, and pH by
31
P nuclear magnetic resonance spectroscopy and of O
2
consumption by fiber-optic oximetry. Experiments were performed under high constant flow (HCF) and under flow-limiting conditions (constant pressure, CP). Despite substantially greater RPP increases relative to baseline during β
1
-AR (HCF, 475%; CP, 150%) than β
2
-AR (HCF, 90%; CP, 72%) stimulation, the relative decrease in the intracellular energy charge relative to baseline was similar for the β
1
(HCF, 49%; CP, 64%) and β
2
(HCF, 59%; CP, 55%) groups. For each group, an increase in oxygen consumption (MV̇
o
2
) occurred commensurate with workload during HCF (β
1
, 141%; β
2
, 30%). During CP, however, the MV̇
o
2
increase was similar (β
1
, 39%; β
2
, 34%), despite the large RPP difference between the groups. During both protocols, there was greater acidosis during β
1
-AR than during β
2
-AR stimulation. Thus, at a given workload, intracellular energy charge decreased, and MV̇
o
2
(CP) increased to a greater extent during β
2
than β
1
-AR stimulation.

Conclusions—

The bioenergetic differences are consistent with access to an additional substrate pool during β
1
-AR stimulation. This may occur via increased glycogenolysis during β
1
-AR stimulation, facilitating increased energy production by oxidative phosphorylation, and under flow-limiting conditions, anaerobic glycolysis.
Role of Interferon-γ in Hypercholesterolemia-Induced Leukocyte–Endothelial Cell Adhesion
Authors: Stokes Karen Y. , Clanton E. Chris , Clements Kris P. , Granger D. Neil
Published: April 2003

Background—

A T-cell–mediated inflammatory response occurs in the microcirculation during acute hypercholesterolemia. The objective of this study was to define the contribution of T-lymphocyte–derived interferon-γ (IFN-γ) to the leukocyte–endothelial cell adhesion induced by hypercholesterolemia.

Methods and Results—

Intravital videomicroscopy was used to quantify the adhesion and emigration of leukocytes and oxidant stress (dihydrorhodamine [DHR] oxidation) in cremasteric venules. Wild-type (WT), IFN-γ
−/−
, and severe combined immunodeficiency (SCID) mice were placed on either a normal (ND) or high-cholesterol (HC) diet for 2 weeks. WT-HC mice exhibited exaggerated adhesion and emigration of leukocytes and enhanced DHR oxidation compared with WT-ND. The exaggerated adhesion responses and increased DHR oxidation were not seen in IFN-γ
−/−
–HC mice. SCID-HC mice also exhibited attenuated inflammatory responses compared with WT-HC. Reconstitution of either SCID-HC or IFN-γ
−/−
–HC mice with WT-HC splenocytes restored the inflammatory responses, whereas reconstitution of SCID-HC with IFN-γ
−/−
–HC splenocytes did not. The HC-induced oxidant stress was restored in IFN-γ
−/−
–HC mice reconstituted with WT-HC splenocytes.

Conclusions—

These findings implicate IFN-γ as a cause of the inflammatory phenotype that is assumed by the microvasculature of hypercholesterolemic mice and suggest that T lymphocytes are a major source of this proinflammatory cytokine.
Low-Density Lipoprotein in Hypercholesterolemic Human Plasma Induces Vascular Endothelial Cell Apoptosis by Inhibiting Fibroblast Growth Factor 2 Transcription
Authors: Chen Chu-Huang , Jiang Tao , Yang Jun-Hai , Jiang Wei , Lu Jonathan , Marathe Gopal K. , Pownall Henry J. , Ballantyne Christie M. , McIntyre Thomas M. , Henry Philip D. , Yang Chao-Yuh
Published: April 2003

Background—

Apoptosis of vascular endothelial cells (ECs) can be induced in vitro by experimentally modified LDL. Description of proapoptotic circulating lipoproteins may significantly enhance understanding of atherothrombosis pathophysiology.

Methods and Results—

Fast protein liquid chromatography of LDL samples from 7 asymptomatic, hypercholesterolemic patients yielded subfractions L
1
–L
5
in increasing electronegativity. L
4
and L
5
were not detectable or collectible in normolipidemic samples. In bovine aortic EC cultures, L
5
induced marked apoptosis and L
4
had a mild effect, whereas hypercholesterolemic or normolipidemic L
1
–L
3
had negligible effects. Compared with copper-oxidized LDL, L
5
was only mildly oxidized, although its propensity to form conjugated dienes in response to copper exceeded that of other subfractions. L
5
-induced apoptosis was associated with suppressed fibroblast growth factor 2 (FGF-2) transcription, as assessed by nuclear run-on analysis. Degrading platelet-activating factor (PAF)-like lipids in L
5
by a recombinant PAF acetylhydrolase prevented both FGF-2 downregulation and apoptosis. Furthermore, the ability of L
5
lipid extract to induce calcium influx into neutrophils was lost after pretreatment of the extract with PAF acetylhydrolase. FGF-2 supplementation, PAF receptor (PAFR) blockade with WEB-2086, and inactivation of PAFR-coupled G
i
protein with pertussis toxin all effectively attenuated L
5
-induced apoptosis.

Conclusions—

Our findings indicate that a highly electronegative, mildly oxidized LDL subfraction present in human hypercholesterolemic but not normolipidemic plasma can induce apoptosis in cultured ECs. The evidence that a freshly isolated LDL species modulates transcription of FGF-2 may provide a physiological insight into the mechanism of vascular EC apoptosis in hypercholesterolemia.
Angiographic Assessment of Reperfusion in Acute Myocardial Infarction by Myocardial Blush Grade
Authors: Henriques Jose P.S. , Zijlstra Felix , van ‘t Hof Arnoud W.J. , de Boer Menko-Jan , Dambrink Jan-Henk E. , Gosselink Marcel , Hoorntje Jan C.A. , Suryapranata Harry
Published: April 2003

Background—

Angiographic successful reperfusion in acute myocardial infarction has been defined as TIMI 3 flow. However, TIMI 3 flow does not always result in effective myocardial reperfusion. Myocardial blush grade (MBG) is an angiographic measure of myocardial perfusion. We hypothesized that optimal angiographic reperfusion is defined by TIMI 3 flow and MBG 2 or 3.

Methods and Results—

In 924 consecutive patients with TIMI 3 flow after angioplasty for acute myocardial infarction, we prospectively studied the value of MBG. End points were death, MACE, enzymatic infarct size, and residual left ventricular ejection fraction. Follow-up was 16±11 months. Of the 924 patients, 101 (11%) patients had MBG 0 or 1. Mortality was significantly higher in patients with MBG 0 or 1 compared with patients with MBG 2 or 3 (relative risk, 4.7; 95% CI, 2.3 to 9.5;
P
<0.001). The combined incidence of MACE was higher in patients with MBG 0 or 1 compared with patients with MBG 2 or 3 (relative risk, 1.8; 95% CI, 1.1 to 2.8;
P
=0.009). Enzymatic infarct size was larger (1437±2388 versus 809±1672,
P
=0.001) and left ventricular ejection fraction was lower (37.7±10.6 versus 43.8±11.1,
P
<0.001) in patients with MBG 0 or 1 compared with patients with MBG 2 or 3.

Conclusions—

MBG is a strong angiographic predictor of mortality in patients with TIMI 3 flow after primary angioplasty. Enzymatic infarct size is larger and residual left ventricular ejection fraction is lower in patients with MBG 0 or 1 compared with MBG 2 or 3. Angiographic definition of successful reperfusion should include both TIMI 3 flow as well as MBG 2 or 3.
Prospective Study of Sudden Cardiac Death Among Women in the United States
Authors: Albert Christine M. , Chae Claudia U. , Grodstein Francine , Rose Lynda M. , Rexrode Kathryn M. , Ruskin Jeremy N. , Stampfer Meir J. , Manson JoAnn E.
Published: April 2003

Background—

There are few data regarding the determinants of sudden cardiac death (SCD) in women, primarily because of their markedly lower rate of SCD compared with men. Nonetheless, existing data, although sparse, suggest possible gender differences in risk factors for SCD.

Methods and Results—

In this prospective cohort of 121 701 women aged 30 to 55 years at baseline, SCD was defined as death within 1 hour of symptom onset. From 1976 to 1998, 244 SCDs were identified. Although the risk of SCD increased markedly with age, the percentage of cardiac deaths that were sudden decreased. Most (69%) women who suffered a SCD had no history of cardiac disease before their death. However, almost all of the women who died suddenly (94%) had reported at least 1 coronary heart disease risk factor. Smoking, hypertension, and diabetes conferred markedly elevated (2.5- to 4.0-fold) risk of SCD, similar to that conferred by a history of nonfatal myocardial infarction (relative risk, 4.1; 95% confidence interval, 2.9 to 6.7). Family history of myocardial infarction before age 60 years and obesity were associated with moderate (1.6-fold) elevations in risk. With regard to mechanism, 88% of SCDs were classified as arrhythmic. In 76% of these, the first rhythm documented was ventricular tachycardia or ventricular fibrillation.

Conclusions—

These prospective data suggest that, as in men, coronary heart disease risk factors predict risk of SCD in women and that SCD is usually an arrhythmic death. Therefore, prevention of atherosclerosis or ventricular arrhythmias may reduce the incidence of SCD in women.
Cardiovascular Control During Exercise
Authors: Dela Flemming , Mohr Thomas , Jensen Christina M.R. , Haahr Hanne L. , Secher Niels H. , Biering-Sørensen Fin , Kjær Michael
Published: April 2003

Background—

We studied the role of the central nervous system, neural feedback from contracting skeletal muscles, and sympathetic activity to the heart in the control of heart rate and blood pressure during 2 levels of dynamic exercise.

Methods and Results—

Spinal cord–injured individuals (SCI) with (paraplegia, n=4) or without (tetraplegia, n=6) sympathetic innervation to the heart performed electrically induced exercise. Responses were compared with those established by able-bodied individuals (control, n=6) performing voluntary exercise at a similar pulmonary oxygen uptake. In all subjects, cardiac output and leg blood flow increased, but in SCI they reached a maximal value. The increase in cardiac output was mainly elicited by an increase in stroke volume in individuals with tetraplegia, whereas in individuals with paraplegia it was by heart rate. The increase in SCI was slow compared with that in controls. During exercise, blood pressure was stable in controls, whereas it decreased over time in SCI and especially in individuals with tetraplegia.

Conclusions—

The autonomic nervous system provides for acceleration of the heart at the onset of exercise, but a slow increase in heart rate is established even without central command, neural feedback from working muscles, or autonomic influence on the heart. Yet an intact autonomic nervous system is a prerequisite for a large rise in cardiac output and in turn leg blood flow during exercise. Thus, when the sympathetic nervous system is injured at a level where it influences the heart, vasodilatation in working muscles challenges blood pressure.
Brain Natriuretic Peptide as a Predictor of Adverse Outcome in Patients With Pulmonary Embolism
Authors: ten Wolde M. , Tulevski I.I. , Mulder J.W.M. , Söhne M. , Boomsma F. , Mulder B.J.M. , Büller H.R.
Published: April 2003

Background—

Despite effective treatment with anticoagulants, 2% to 7% of patients with pulmonary embolism will die as a result of their disease.

Methods and Results—

We examined in 110 consecutive patients with pulmonary embolism whether plasma brain natriuretic peptide (BNP), a novel marker of (right) ventricular dysfunction, is a predictor of fatal pulmonary embolism. The relationship between BNP concentration measured at presentation and clinical outcome was assessed by comparing the proportion of outcome events among tertiles. Positive and negative predictive values of BNP levels in the highest and lowest tertiles were calculated. The risk of death related to pulmonary embolism if the BNP level is >21.7 pmol/L is 17% (95% CI, 6% to 33%). The negative predictive value for uneventful outcome of a BNP value <21.7 pmol/L is 99% (95% CI, 93% to 100%).

Conclusion—

This is the first study to show that plasma BNP levels seem to predict adverse outcome in patients with acute pulmonary embolism.