bluuebunny/crossref_metadata_2025 huggingface dataset:
PION ELLIPTIC FLOW AND HBT INTERFEROMETRY IN A GRANULAR QUARK-GLUON PLASMA DROPLET MODEL
Authors: ZHANG WEI-NING , REN YAN-YU , WONG CHEUK-YIN
Published: October 2007

We use a model of quark-gluon plasma granular droplets that evolve hydrodynamically to investigate pion elliptic flow and Hanbury–Brown–Twiss interferometry. We find that the data of pion transverse momentum spectra, elliptic flows, and HBT radii in [Formula: see text] Au + Au collisions at RHIC can be described well by an expanding source of granular droplets with an anisotropic velocity distribution.
INCLUSIVE PHOTON v2 AND THE APPROACH TO DIRECT PHOTON v2 IN $\sqrt{^SNN} = 200\ {\rm GEV}$AU+AU COLLISIONS
Authors:   for the STAR Collaboration, LIN GUOJI
Published: October 2007

We present the STAR preliminary results of inclusive photon v2 as a function of pT in [Formula: see text] AU + AU collisions. Photons are identified in the STAR Barrel Electromagnetic Calorimeter (BEMC). Non-flow effects are suppressed by obtaining the event plane in different pseudo-rapidity regions. The v2 of π0 decay products is calculated from the known v2 and spectra of hadrons and is compared to the inclusive photon v2. The comparison indicates that direct photon v2 is small.
ENERGY AND SYSTEM SIZE DEPENDENCE OF PHOTON PRODUCTION AT FORWARD RAPIDITIES AT RHIC
Authors:   for the STAR Collaboration, SHARMA MONIKA , DOGRA SUNIL , GUPTA NEERAJ
Published: October 2007

The energy and system size dependence of pseudorapidity (η) and multiplicity distributions of photons are measured in the region −2.3 ≤ η ≤ −3.7 for Cu + Cu collisions at [Formula: see text] and 62.4 GeV. Photon multiplicity measurements at forward rapidity have been carried out using a Photon Multiplicity Detector (PMD) in the STAR experiment. Photons are found to follow longitudinal scaling for Cu + Cu collisions for 0–10% centrality. A Comparison of pseudorapidity distributions with HIIJING model is also presented.
A METHOD FOR MEASURING ELLIPTIC FLOW FLUCTUATIONS WITH THE PHOBOS DETECTOR
Authors:   for the PHOBOS collaboration, ALVER BURAK
Published: October 2007

We have performed the first measurement of elliptic flow (v2) fluctuations in nucleus-nucleus collisions. In this paper, we describe the analysis method we have developed for this measurement. In this method, v2 is determined event-by-event by a maximum likelihood fit. The non-statistical fluctuations are determined by unfolding the contribution of statistical fluctuations and detector effects using Monte Carlo simulations. Application of this method to measure dynamical fluctuations in events from a different Monte Carlo event generator is presented.
ENERGY AND SYSTEM SIZE DEPENDENCE STUDY OF THE PERCOLATION PHASE TRANSITION
Authors:   for the STAR Collaboration, TARNOWSKY TERENCE , SCHARENBERG ROLF , SRIVASTAVA BRIJESH
Published: October 2007

Multiparticle production at high energies is described in terms of color strings stretched between the projectile and target. As the string density increases, overlap in the transverse plane leads to cluster formation. At some critical density a macroscopic cluster appears, spanning the entire system. This marks the percolation phase transition. Data from [Formula: see text] p + p , d + Au and Au + Au collisions at RHIC has been analyzed using the STAR detector to obtain the percolation density parameter, η. The particle pT spectrum from 200 GeV p + p data is parametrized using a power law. Values of the fit parameters are used in the d + Au and Au + Au analysis. For 200 GeV Au + Au collisions, the value of η is found to lie above the critical percolation threshold, while for other collision systems and energies, it is below the critical value. This supports the idea of string percolation, which at high enough string density is a possible mechanism to explore the hadronic phase transition to a quark-gluon plasma.
MEASUREMENT OF THE MULTI-HADRON DECAYS OF ω, $K^0_S$ AND η-MESONS IN HEAVY ION COLLISIONS AT $\sqrt{^SNN} = 200\ {\rm GeV}$ IN THE PHENIX EXPERIMENT AT RHIC
Authors:   for the PHENIX Collaboration, RYABOV V.
Published: October 2007

The PHENIX experiment at RHIC measured ω, η and [Formula: see text]-meson production at high pT in p + p, d + Au and Au + Au collisions at [Formula: see text]. Measurements performed in different hadronic decay channels give consistent results. The measured ratios of all three mesons to π0 are found to be flat as a function of pT in p + p collisions and equal to ω/π0 = 0.81 ± 0.02 ± 0.07, η/π0 = 0.48 ± 0.02 ± 0.02 and [Formula: see text]. Nuclear modification factor measured for ω-mesons in central Au + Au collisions is RAA = 0.4 ± 0.15.
ANISOTROPIC FLOWS OF Ω BARYON DUE TO PARTON CASCADES
Authors: ZUO J. X. , CAI X. Z. , CHEN J. H. , MA G. L. , MA Y. G.
Published: October 2007

The directed flow v1, elliptic flow v2 and the fourth order anisotropic flow v4 of Ω, p, K and π have been studied in the framework a parton cascade model, namely A Multi-Phase Transport (AMPT) model for 197 Au + 197 Au collisions at [Formula: see text]. Transverse momentum (pT) dependence of v2 and v4 and rapidity dependence of v1 are presented. The results show that the v2 of Ω obeys the constituent quark number scaling which has been observed for other mesons and baryons. It is seen that [Formula: see text] is scaled better by 1.2 than 0.5. The comparisons of Ω elliptic flow v2 among the default version of AMPT, the melting version of AMPT and RQMD model calculation shows that parton scattering process is important to reproduce the sizeable v2, and the string melting AMPT model preferably reproduces Ω elliptic flow v2.
JET MODIFICATION AND A COMPARATIVE STUDY OF HADRON v2 MEASUREMENTS IN $\sqrt{^SNN} = 200\ {\rm GeV}$Au+Au COLLISIONS AT RHIC-PHENIX
Authors:   for the PHENIX Collaboration, VAZQUEZ ERIC
Published: October 2007

In this analysis we measure the azimuthal angle (φ) dependence of hadrons with respect to the reaction plane (ΨRP) in events that were triggered by a high-pT π0 of 5-10 GeV. Fitting the distribution of hadrons with a function of the type ξ(1 + 2v2 cos (2(φ − ΨRP))), we observe that there is no significant statistical difference between v2 inclusive hadrons and those hadrons from hard scattering events. We also compare the near-side jet widths using PYTHIA simulations with h±−h± correlations in Au + Au at [Formula: see text].
HEAT CAPACITY RELEVANT TO QGP PHASE TRANSITION AT $\sqrt{^SNN} = 200\ {\rm GeV}$
Authors: LI XIAO-MEI , HU SHOU-YANG , FENG JING , LI SHOU-PING , SA BEN-HAO , ZHOU DAI-MEI
Published: October 2007

A parton and hadron cascade model, PACIAE, is applied to follow the particle transport in both the partonic and hadronic stages of the 0–5% most central Au + Au collisions at [Formula: see text]. We have determined the specific heat of π+ + π− in pure hadronic scenario (hadonic final state) and the specific heat of [Formula: see text] in pure partonic scenario (partonic initial state). The specific heat of π+ + π− in hadronic scenario is nearly a factor of 1.2 smaller than that of [Formula: see text] in partonic scenario. However, the specific heat of [Formula: see text] is very hard to survive the hadronization.
“TEMPERATURE” FLUCTUATION AND HEAT CAPACITIES OF QUARKS AND π MESON
Authors: SHI X. H. , MA G. L. , MA Y. G. , CAI X. Z. , CHEN J. H.
Published: October 2007

Specific heat capacities of π meson and different quarks after parton cascade AMPT model in Au + Au collisions at [Formula: see text] have been tentatively extracted from the event-by-event temperature fluctuations in the region of low transverse mass. The specific heat capacity of π meson shows a slight dropping trend with increasing impact parameter. The specific heat capacities of different quarks increase with the mass of quark, and the sum of up and down quark's specific heat capacities was found to be approximately equal to that of π meson.
DOES THE CRONIN PEAK DISAPPEAR AT LHC ENERGIES?
Authors: BARNAFÖLDI GERGELY GÁBOR , LÉVAI PÉTER , FAI GEORGE , PAPP GÁBOR , COLE BRIAN A.
Published: October 2007

In this work we compare the nuclear modification factors in proton (deuteron) — nucleus collisions at CERN SPS, FNAL and RHIC energies in a wide pT range. In these experiments the nuclear modification factor has shown an enhancement at pT ≈ 4 GeV /c. The height of this “Cronin peak” depends on the c.m. energy of the collision, as it is subject to stronger shadowing at higher energies. One of the aims of this contribution is to analyze the shadowing phenomenon at lower (2 GeV / c ≲ pT ≲ 4 GeV / c ) and intermediate (4 GeV / c ≲ pT ≲ 8 GeV / c ) transverse momentum. Different shadowing parametrizations are considered and the obtained Cronin peaks are investigated at RHIC and LHC energies.
SIMULATION OF JET QUENCHING OBSERVABLES IN HEAVY ION COLLISIONS AT THE LHC
Authors:   for the CMS Heavy Ion Group, ROLAND CHRISTOF , VERES GÁBOR I. , KRAJCZÁR KRISZTIÁN
Published: October 2007

Large transverse momentum jets provide unique tools to study dense QCD matter in high-energy heavy-ion collisions. Results from RHIC on suppression of high transverse momentum particles in Au + Au collisions indicate a significant energy loss of leading partons in the dense and strongly interacting matter formed in these collisions. The LHC will collide Pb ions at [Formula: see text], where the cross section of hard scattering will increase dramatically. Large production rates, the large acceptance of the CMS calorimeters and tracking system, combined with the capability of triggering on jets, will extend the transverse momentum reach of charged particle spectra and nuclear modification factors up to pT > 200 GeV / c .
IDENTIFIED PARTICLE NUCLEAR MODIFICATION FACTORS AT RAPIDITY 0–3.8 IN AU+AU COLLISIONS AT $\sqrt{^SNN} = 200\ {\rm GEV}$
Authors:   for the BRAHMS Collaboration, RISTEA CATALIN
Published: October 2007

We present the transverse momentum spectra for charged hadrons as well as for identified particles produced in Au + Au and p + p collisions at [Formula: see text] for different event centralities (minimum bias spectra for p + p) in narrow rapidity ranges (±0.1), for midrapidity and high rapidities (up to 3.8). Nuclear modification factor RAA for identified baryons and mesons, as well as for inclusive charged hadrons, at rapidities from 0 to 3.8 will be shown and discussed.
MACH CONES AND JET ENERGY LOSS STUDIES IN FULL (3+1)DIMENSIONAL IDEAL HYDRODYNAMICS
Authors: BETZ BARBARA , PAECH KERSTIN , RISCHKE DIRK H. , STÖCKER HORST
Published: October 2007

A vigorous debate has recently concerned the quenching of jets by the expanding hot and dense medium created in high-energy nuclear collisions accompanied by Mach-cone-like structures at STAR and PHENIX.1,2 Large angle (w.r.t. the jet axis) peaks in the angular distribution of the particles created in the jet show up in both, 2- and 3-particle correlations. It is assumed that this reflects the interaction of the jet with the medium.3,4 However, the jet interactions with the medium are theoretically not understood well enough. Therefore, we present a first ideal (3+1)dimensional hydrodynamics approach with a sudden jet-energy deposition. Clearly, the hydrodynamical evolution strongly depends on the underlying equation of state (EoS) of the medium and therefore the influcence of the EoS on the evolution of the jet through the medium is of great interest for probing the EoS, the nature of the phase transition.
PHOTON-HADRON CORRELATIONS IN $\sqrt{^SNN} = 200\ {\rm GeV/c}$ COLLISIONS WITH THE PHENIX DETECTOR
Authors: NGUYEN MATTHEW
Published: October 2007

The yield of charged hadrons at intermediate pT (2-5 GeV/c) on the away-side of a high pT hadron trigger is known to be suppressed in central relativistic heavy-ion collisions. The mechanism by which the jet opposite the trigger has its redistributed is not yet fully understood. Although rarer than dijets, direct photon-jet pairs may provide additional constraints on parton energy loss models. The benefits of direct photon triggers are two-fold. In contrast to dijet systems where the jet energy is known only after full jet reconstruction, the direct photon carries approximately the full energy of the jet. Also, the trigger photons do not suffer from the same geometrical bias that causes high pT hadrons from jets to be produced predominately near the surface of the collision region. This poster discusses the method by which the direct photon correlation signal can be separated from the decay photon correlation signal. We present the results of two particle correlation studies of charged hadrons associated with high pT photon triggers in p − p collisions. The results are compared to data from Au−Au collisions and expectations from the PYTHIA event generator.
π0–h CORRELATION IN Cu+Cu AT $\sqrt{^SNN} = 200\ {\rm GeV}$
Authors:   for the PHENIX (For the full list of PHENIX authors and acknowledgements, see Appendix “Collaborations” of this volume) Collaboration., JIA JIANGYONG
Published: October 2007

We present the results of the two-particle Δφ correlation between high pT π0 and charged hadrons in Cu + Cu collisions at [Formula: see text]. Clear away-side jet signals are seen in central Cu + Cu collisions at all associated hadron pT, albeit suppressed by factor of 2 above 2 GeV /c. This level is similar to the suppression seen for inclusive hadrons at high pT (> 7 GeV /c). However, this agreement is argued to be the result of a cancellation between a flatter away-side parton spectra due to the requirement of high pT triggers and a bigger energy loss due to a longer path length traversed by the away-side jet.
AZIMUTHAL CORRELATIONS BETWEEN PHOTONS AND CHARGED HADRONS IN p+p AND d+Au COLLISIONS AT $\sqrt{^SNN} = 200\ {\rm GeV}$
Authors:   for the STAR Collaboration, BENEDOSSO FEDERICA
Published: October 2007

We present a systematic analysis of azimuthal correlations between inclusive photons detected in the STAR Barrel Electromagnetic Calorimeter and tracks measured in the Time Projection Chamber in p + p and d + Au collisions. These measurements provide insight in basic properties of jet fragmentation in p + p and d + Au collisions at RHIC energies and also serve as a reference for medium-modified fragmentation in nuclear collisions. The on-line trigger on high-pT photons in the Barrel Calorimeter provides a substantial sample of triggered events with photons at high-pT. Even at this pT, the photon sample is dominated by π0 decays, allowing to explore jet fragmentation with a leading π0 in detail.
MEDIUM EFFECT ON JET CORRELATIONS IN Cu+Cu COLLISIONS AT $\sqrt{^SNN} = 200\ {\rm GeV}$ at RHIC-PHENIX
Authors:   for the PHENIX Collaboration, PEI HUA
Published: October 2007

Strong di-jet correlations have been observed in p + p and d + Au collisions at [Formula: see text]. It is important to study how this jet-correlation is affected by the hot, dense medium produced in heavy-ion collisions at RHIC. In this contribution we will study the two particle correlation and probe how the di-jet shape evolves as a function of centrality in Cu + Cu collisions comparing to p + p , specifically using the near-side width and pT out . We will use high pT reconstructed π0 as our identified trigger in tagging jets.
CENTRALITY, TRANSVERSE MOMENTUM AND PSEUDORAPIDITY DEPENDENCES OF “MACH-LIKE” CORRELATIONS IN A PARTONIC TRANSPORT MODEL
Authors: ZHANG SONG , MA G. L. , MA Y. G. , CAI X. Z. , CHEN J. H.
Published: October 2007

It has been observed a “Mach-like” structure of di-hadron azimuthal correlations in Au + Au central collisions at [Formula: see text] in the framework of a multi-phase transport model (AMPT) with both partonic and hadronic interactions. In this paper, we will show centrality, transverse momentum (pT) and pseudorapidity (η) dependences of “Mach-like” structure. The splitting parameter D, i.e. half distance between two splitting peaks on away side, decreases with the impact parameter b (corresponding to centrality) and slightly increases with transverse momentum of associated hadrons [Formula: see text], which from string melting AMPT version is consistent with experimental results. And the splitting parameter D is flat in mid-pseudorapidity region and rapidly decreases with the increasing of high-|η assoc |.
STRANGENESS PRODUCTION IN Au+Au REACTIONS AT $\sqrt{^SNN} = 62.4\ {\rm GeV}$
Authors:   for the (BRAHMS Collaboration), ARSENE IONUT-CRISTIAN
Published: October 2007

The measurement of strangeness is a valuable tool for understanding the reaction mechanism of nuclear collisions since all the strange particles need to be created during the reaction. Also, strangeness enhancement is one of the predicted signals of the QGP. In the present work we will discuss the behaviour of the strangeness production (i.e. K/π ratio) with rapidity and baryo-chemical potential in Au + Au collisions at 62.4 A GeV. In this particular reaction, BRAHMS is able to identify particles over 3.5 rapidity units and thereby cover a wide range of [Formula: see text] ratios, including the fragmentation region. We will show spectra and ratios of identified particles as a function of pT and rapidity.
STUDYING THE ENERGY LOSS OF HEAVY QUARKS VIA SINGLE MUON PRODUCTION IN PbPb COLLISIONS AT $\sqrt{^SNN} = 5.5 {\rm TeV}$
Authors: DING HENG-TONG , DAINESE ANDREA , DEL VALLE ZAIDA CONESA , ZHOU DAICUI
Published: October 2007

The effects of heavy quarks energy loss on the transverse momentum spectra of single muons are studied. The energy loss of heavy quarks when traversing the medium formed in PbPb collisions at [Formula: see text] is calculated by implementing the collision geometry and the quenching weights. The medium density is assumed to decrease at forward pseudo-rapidity and to be proportional with pseudo-rapidity multiplicity dN/dη. Muons from W decays can be used as a medium-blind reference to quantify the effect of heavy quarks energy loss on the single muon production.
J/ψ AZIMUTHAL DISTRIBUTION RELATIVE TO THE REACTION PLANE IN Pb-Pb COLLISIONS AT 158 GeV/NUCLEON
Authors:   for the NA50 collaboration, PRINO FRANCESCO
Published: October 2007

J/ψ azimuthal distribution relative to the reaction plane has been studied Pb - Pb collisions at 158 A GeV /c. Different [Formula: see text] absorption mechanisms are expected to induce J/ψ azimuthal anisotropy at this energy. The present analysis has been performed on the data sample of 100 000 J/ψ's collected in year 2000 by the NA50 Collaboration. The reaction plane is estimated from the azimuthal distribution of the neutral transverse energy measured by the electromagnetic calorimeter. The numbers of J/ψ's in different bins of azimuthal angle relative to the reaction plane as well as the Fourier coefficients [Formula: see text] and [Formula: see text] (uncorrected for event plane resolution) are presented in this paper.
MEASUREMENTS OF MULTI-STRANGE (ANTI-)BARYON PRODUCTION IN Cu+Cu COLLISIONS WITH THE STAR EXPERIMENT AT RHIC
Authors:   for the STAR Collaborationfor the STAR Collaboration, MUNHOZ M. G. , TAKAHASHI J.
Published: October 2007

Strange particle production has always been an important probe to study various aspects of the high density, strong interacting matter created in ultra-relativistic heavy-ion collisions. Yields and spectra of strange hadrons have been measured by the STAR experiment for center of mass energies of 62.4 GeV, 130 GeV and 200 GeV per nucleon pair for Au + Au , p + p and d + Au collisions. We have now measured Cu + Cu collisions at 62.4 GeV and 200 GeV, complementing the study of the system size dependence initiated with the centrality dependence study of Au + Au data. We will present preliminary results on Ξ, Ω and their anti-particles produced in Cu + Cu collisions. Yields and ratios are compared to results from Au + Au collisions normalized by the equivalent number of participants. The nuclear modification factor of the measured particles from Cu + Cu data also shows the same suppression effects in the high transverse momentum region and a baryon/meson difference in the intermediate momentum region.
OPEN CHARM RECONSTRUCTION IN ALICE: D+ → K−π+π+
Authors:   for the ALICE Collaboration, BRUNA ELENA
Published: October 2007

Open charm mesons produced in high energy A-A interactions are expected to be powerful probes to investigate the medium produced in the collision. In this context it is important to measure the production of as many charmed hadrons as possible, such as D 0, D +, [Formula: see text] and Λc, because the measurement of their relative yield can provide information on the hadronization mechanism and is necessary to reduce the systematic error on the absolute cross section. The ALICE experiment at the LHC is designed to perform such measurements at midrapidity down to pT below 1 GeV/c, mainly by means of the silicon vertex and tracker detector, the time projection chamber and the time of flight detector. One of the main channels for the detection of charm production in ALICE is the exclusive reconstruction of the D + meson through its three charged body decay K−π+π+ in Pb - Pb [Formula: see text] and pp [Formula: see text] collisions. The selection strategies for this analysis and the results of a feasibility study on Monte Carlo events will be presented together with the perspectives for the study of D + quenching and azimuthal anisotropy measurements.
K*(892) PRODUCTION IN Au+Au COLLISIONS AT RHIC
Authors:   for the STAR Collaboration, DONG XIN , TANG ZEBO , DASH SADHANA
Published: October 2007

Short-lived resonances are useful tools to probe the property of the matter created in heavy ion collisions. Measurements of their production yields and elliptic flow allow us to understand particle production mechanisms as well as the system evolution after hadronization. We report the measurements of transverse momentum (pT) spectrum and anisotropic parameter v2 of K* resonance from a high statistics data set of Au + Au collisions at [Formula: see text] taken by the STAR experiment in year 2004. The K* are measured up to intermediate pT region pT < 5 GeV /c at mid-rapidity through its hadronic decay channel. Its nuclear modification factor as well as elliptic flow are compared with corresponding results for [Formula: see text] and Λ up to intermediate pT to check the number of constituent quark scaling for resonances. Combined with the K*/K and φ/K* yield ratios, the production mechanism of K* is discussed. The first results on K* mT spectra from Au + Au 62.4 GeV are presented to understand the energy dependence of K* production.
ϒ MEASUREMENT IN STAR
Authors:   for the STAR Collaboration, COSENTINO MAURO R.
Published: October 2007

We present preliminary results of ϒ production in p + p collisions at [Formula: see text] at central rapidity. This measurement was performed at the STAR experiment through the ϒ → e+ e− decay channel. In this manuscript we describe the experimental details, from the development of a specially designed trigger setup to the analysis methods used to discriminate electrons from hadrons. The production cross-section obtained [Formula: see text] pb is compatible with our expectations based on pQCD calculations.
THERMAL DILEPTON PRODUCTION FROM DROPPING ρ IN THE VECTOR MANIFESTATION
Authors: HARADA MASAYASU , SASAKI CHIHIRO
Published: October 2007

We study the pion electromagnetic form factor and the dilepton production rate in hot matter based on the vector manifestation (VM) of chiral symmetry in which the massless vector meson becomes the chiral partner of the pion, giving a theoretical framework of the dropping ρ à la Brown–Rho scaling. The VM predicts a strong violation of the vector dominance (VD) near the phase transition point associated with the dropping ρ. We present the effect of the VD violation to the dilepton production rate and make a comparison to the one predicted by assuming the VD together with the dropping ρ.
OBSERVATION OF ΔφΔη SCALED CORRELATION SIGNALS WHICH INCREASE WITH CENTRALITY OF AuAu COLLISIONS AT $\sqrt{^SNN} = 200\ {\rm GeV}$
Authors:   Star Collaboration, LONGACRE R. S.
Published: October 2007

We show the preliminary charged-particle pair correlation analyses presented in a poster session at the 2006 International Quark Matter Conference in Shanghai China. The correlation analysis space of Δφ (azimuth) and Δη (pseudo-rapidity) are considered as a function of centrality for minimum bias Au + Au collisions in the mid-transverse momentum range in the STAR detector. The analyses involve unlike-sign charge pairs and like-sign charge pairs, which are transformed into charge-dependent (CD) signals and charge-independent (CI) signals. We use a multiplicity scale to compare the different centralities. We find the signals increase with increasing centrality. A model featuring dense gluonic hot spots as first proposed by van Hove predicts that the observables under investigation would have sensitivity to such a substructure should it occur. A blast wave model including multiple hot spots motivates the selection of transverse momenta in the range 0.8 GeV /c < pt < 4.0 GeV /c.
MULTI-CHANNEL MEASUREMENTS OF LIGHT VECTOR MESONS AT PHENIX
Authors:   PHENIX Collaboration, SHIGAKI KENTA
Published: October 2007

The PHENIX experiment at RHIC is uniquely suitable for systematic studies of light vector mesons, whose mass states are considered as a sensitive probe of partial chiral symmetry restoration and as a signature of deconfined partonic state of matter. Their challengingly small signal to background ratios in multi body decay channels in heavy ion collisions have been extensively attacked. Significant improvements have been recently achieved of signal extraction techniques. The final results on yields, transverse momentum spectra, and possibly mass states of light vector mesons including φ and ω are well in the near future prospects.
AZIMUTHAL ANISOTROPY MEASUREMENT OF DIRECT PHOTON IN $\sqrt{^SNN} = 200\ {\rm GeV}$Au + Au COLLISIONS AT RHIC-PHENIX
Authors:   PHENIX(For the full list of PHENIX collaboration and acknowledgements, see Ref. 5.) Collaboration, MIKI KENTARO
Published: October 2007

Azimuthal anisotropy of direct photons is measured in [Formula: see text] Au + Au collisions by the PHENIX experiment at RHIC. Direct photons are one of the most effective probes to study properties of hot dense medium at initial state (also QGP state) of heavy ion collisions because photons do not interact strongly with medium once produced. They keep their conditions when they are created. Within statistical and systematic errors, the elliptic flow parameter (v2) of direct photons is consistent with zero. Direct photons v2 is measured by the hadron decay photon background v2 from inclusive photon v2 in intermediate to high transverse momentum (pT) region (0 to 10 GeV/c) for 3 centrality selections (20% steps) and minimum bias.
MEASURING BREMSSTRAHLUNG PHOTONS IN $\sqrt{S} = 200\ {\rm GeV}$p-p COLLISIONS
Authors:   PHENIX(For the full list of PHENIX authors and acknowledgements, see Appendix “Collaborations” of this volume.) Collaboration, HANKS ALI
Published: October 2007

Direct photon production is an important observable in heavy ion collisions, as photons are penetrating and therefore largely insensitive to final state effects. Measurements of the fragmentation component of direct photon yields in p + p and Au + Au collisions will provide important tests of pQCD predictions and of predictions for modifications of this component in heavy ion collisions. By selecting photons associated with jets on the same side using hadron-photon correlations, fragmentation photons can be measured directly.
OPTIMIZED ARTIFICIAL DISSIPATION TERMS FOR ENHANCED STABILITY LIMITS
Authors: GROGGER HERWIG A.
Published: October 2007

Finite difference approximations for the convection equation are developed, which exhibit enhanced stability limits for explicit Runge–Kutta integration. Stability limits are increased by adding artificial dissipation terms, which are optimized to yield greatest stable time steps. For the artificial dissipation terms, symmetric finite difference approximations of even-order derivatives are used with differencing stencils equal to the convective stencils. The spatial discretization inclusive of the added dissipation term is shown to be consistent with a first derivative. The formal order of accuracy in space is decreased by one order, while the order of time integration is not affected. As a result, the time step limits of originally stable Runge–Kutta integration is increased, for some combinations of spatial discretization and time integration by a factor of two. Algorithms, which are unstable without damping are stabilized. The dispersion properties of the algorithms are not influenced by the proposed damping terms. Spectral analysis of the algorithms show very low dissipation error for dimensionless wave numbers k Δ x < 0.5. Stability conditions based on von Neumann stability analysis are given for the proposed schemes for explicit Runge–Kutta time integration of orders up to ten.
STAGES OF SMALL ENTERPRISE DEVELOPMENT: A COMPARISON OF CANADIAN FEMALE AND MALE ENTREPRENEURS
Authors: ZINGER J TERENCE , LEBRASSEUR ROLLAND , ROBICHAUD YVES , RIVERIN NATHALY
Published: October 2007

The explosive growth in the rate of new business formation by women has spurred renewed research interest in the area of female entrepreneurship and its related economic impact. Yet, there has been a dearth of research into the influence of gender on new venture formation and development. This study draws on data from the annual survey of the Global Entrepreneurship Monitor to examine the differences between female and male entrepreneurs in the early stages of small enterprise development. The data was aggregated for the period 2002 through 2004, and consisted of 444 Canadian entrepreneurs: 164 females and 280 males.

Gender differences are explored within the context of a variety of personal as well as business-related variables. Women entrepreneurs had a much greater propensity to have established a consumer or business services enterprise, and reported significantly lower income levels. In addition, they were less likely than their male counterparts to work full time at their business, to utilize new technology or to anticipate new business opportunities in the near term.

In terms of the enterprise's stage of development, it was found that 62 percent of the enterprises operated by females were ‘nascent’ small firms, while 38 percent were ‘new;’ the respective proportions for males were 55 percent and 45 percent. The analysis revealed that the difference between genders on business-related variables strengthens as the firm evolves through the stages of development from nascent to new; however, there was mixed support for the corollary hypothesis that differences in personal characteristics and attitudes diminish during this progression: even for ventures that have reached the ‘new’ phase, personal variables continue to act as important discriminators between genders.

The paper provides a discussion of the implications of these empirical findings, as well as some directions for future research.
LABOUR IS HOLY BUT BUSINESS IS DANGEROUS: ENTERPRISE VALUES FROM THE CHURCH FATHERS TO THE REFORMATION
Authors: DODD SARAH DRAKOPOULOU , GOTSIS GEORGE
Published: October 2007

This paper seeks to explore the religious valuation of entrepreneurship during a long period of Western cultural history that covers transformations of religious thinking from the early Church Fathers to the Reformation. The paper focuses on theological contributions to conceptualizations of labour, property and wealth, that serves as a basis for assessing entrepreneurial motives and enterprise activities. In doing so, this approach highlights the interactions between work motivation and entrepreneurship in distinct cultural and historical contexts. Particular attention is devoted to understanding the religious sanctification of labour. The emergence and formation of secular enterprise values are discussed and interpreted as integral parts of these religious worldviews in which they were deeply embedded.
APPROACHING A DEEPER UNDERSTANDING OF CORPORATE ENTREPRENEURSHIP - FOCUSING ON CO-EVOLUTIONARY PROCESSES
Authors: HEINONEN JARNA , TOIVONEN JOUKO
Published: October 2007

Previous studies on CE behaviour and processes have neglected the role of employees, as the focus has been on one-way relationships (top-down) and the interaction between them. We question the straightforward model of CE implementation and suggest causality between different elements. This conceptual study discusses the different organisational and individual pre-requisites in order to promote understanding of how they confront in the CE context. We propose that top-down and bottom-up influences are parallel terms describing the co-evolution of managerial and employee behaviour and organisational structures. We conclude by introducing the concept of implementation and influencing modalities and conversational space, which enables the ‘voices’ of managers and subordinates to meet and negotiate. Finally, we argue that CE is a two-way interactive and recursive process in which structures and managerial initiatives affect individual behaviour, and individual behaviour affects structures and management behaviour. The paper discusses the implications and gives direction for further research endeavours.
TWO-STAGE METRIC LEARNING PROCEDURE FOR FACIAL SIGNATURE AUTHENTICATION
Authors: SATONAKA TAKAMI , UCHIMURA KEIICHI
Published: October 2007

We present the two-stage adaptive metric learning procedure with improved generalization of missing training data for facial signature authentication. The conventional learning models suffer from degraded recognition rates due to poor estimation of decision boundary to classify impostor patterns. The two-stage networks combine multiple image synthesis methods to assume mixture patterns of training classes and facilitate threshold setting of false acceptance/rejection rates. The margin size of a decision boundary is adjusted to input patterns obtained from synthesized images and depends on the choice of the mixing factor. The present method effectively reduces the margin of a class with an improved recognition rate to classify impostor patterns from 82.2% to 98.8%. Furthermore, we examine the margin structure of the mixture distributions by using the Support Vector Machines.
ROBUST HUMAN DETECTION AND IDENTIFICATION BY USING STEREO AND THERMAL IMAGES IN HUMAN ROBOT INTERACTION
Authors: GUAN F. , LI L. Y. , GE S. S. , LOH A. P.
Published: October 2007

In this paper, robust human detection is investigated by fusing the stereo and infrared thermal images for effective interaction between humans and socially interactive robots. A scale-adaptive filter is first designed for the stereo vision system to detect human candidates. To eliminate the difficulty of the vision system in distinguishing human beings from human-like objects, the infrared thermal image is used to solve the ambiguity and reduce the illumination effect. Experimental results show that the fusion of these two types of images gives an improved vision system for robust human detection and identification, which is the most important and essential component of human robot interaction.
THE INFLUENCE OF AUSTRALIAN ENVIRONMENTAL PROTECTION AUTHORITY PROSECUTIONS ON CORPORATE ENVIRONMENTAL DISCLOSURES
Authors: GADENNE DAVID , LADEWIG JONATHAN
Published: October 2007

This paper examines the environmental disclosure practices of companies that have been prosecuted by the EPA to determine whether the situation has changed since the landmark study conducted by Deegan and Rankin in 1996. The study was conducted by undertaking content analysis of a group of companies that had been prosecuted by the EPA, matched with non-prosecuted companies. Three types of environmental disclosures were considered — positive, negative, and neutral. It was found that companies increased only negative and neutral disclosures if prosecuted, and that disclosures had significantly increased since the Deegan and Rankin (1996) study, the latter finding most likely due to new legislation governing environmental disclosure. However, there was no correlation between the penalty amount and the disclosures that companies made, indicating that penalty amount does not impact on company disclosure practices.
VIRTUAL WATER: A FRAMEWORK FOR COMPARATIVE REGIONAL RESOURCE ASSESSMENT
Authors: SCHENDEL EMILY KATE , MACDONALD JENNIFER R. , SCHREIER HANS , LAVKULICH LES M.
Published: October 2007

New developments in water resource allocation techniques range from local management of green water to international trade in water. A further extension of this is through the virtual water concept, which is the water required to produce a crop or product. The virtual water content of many products is now available at a national and global scale. While these calculations are meaningful in international trade debates, they are not useful to water managers since regional climatic and management conditions are highly variable. The utility of the virtual water concept at a smaller scale is illustrated by a comparison of agricultural crops in the driest and wettest agro-climatic regions in Canada. Results were compared to national and international global calculations. The calculations are highly sensitive to local conditions, and locally collected data needs to be aggregated and compared in order to be made useful to water managers and land use planners.
Forward Genetic Dissection of Immunity to Infection in the Mouse
Authors: Vidal S.M. , Malo D. , Marquis J.-F. , Gros P.
Published: October 2007

Forward genetics is an experimental approach in which gene mapping and positional cloning are used to elucidate the molecular mechanisms underlying phenotypic differences between two individuals for a given trait. This strategy has been highly successful for the study of inbred mouse strains that show differences in innate susceptibility to bacterial, parasitic, fungal, and viral infections. Over the past 20 years, these studies have led to the identification of a number of cell populations and critical biochemical pathways and proteins that are essential for the early detection of and response to invading pathogens. Strikingly, the macrophage is the point of convergence for many of these genetic studies. This has led to the identification of diverse pathways involved in extracellular and intracellular pathogen recognition, modification of the properties and content of phagosomes, transcriptional response, and signal transduction for activation of adaptive immune mechanisms. In models of viral infections, elegant genetic studies highlighted the pivotal role of natural killer cells in the detection and destruction of infected cells.
Influence of the Dose on the Severity of Opiate Withdrawal Symptoms during Methadone Detoxification
Authors: Glasper Anthony , Gossop Michael , de Wet Cornelis , Reed Laurence , Bearn Jennifer
Published: October 2007

Aim: This study investigates factors influencing the severity of opiate withdrawal symptoms, focusing on the relationship between methadone dose and withdrawal severity among opiate-dependent in-patients receiving methadone detoxification. Methods: The sample comprised 48 opiate-dependent patients admitted to a specialist in-patient drug treatment service and withdrawn from opiates, using a 10-day methadone reduction schedule. The severity of withdrawal symptoms was assessed daily using the Short Opiate Withdrawal Scale. Results: Patients withdrawn from higher doses of methadone and those reporting higher levels of anxiety reported more severe withdrawal symptoms. No relationship was found between methadone dose and completion of detoxification or length of hospital stay. Conclusions: Although patients on higher doses of methadone reported more severe opiate withdrawal symptoms than patients on lower doses, the dose effect accounted for only a small percentage of the total variance. Nonetheless, the finding of a dose-response effect supports one of the basic principles of clinical practice during detoxification, namely the matching of the medication withdrawal schedule to the pre-admission opiate dose.
A Comparative Study of CYP3A4 Polymorphisms in Mexican Amerindian and Mestizo Populations
Authors: Reyes-Hernández Octavio D. , Lares-Asseff Ismael , Sosa-Macias Martha , Vega Libia , Albores Arnulfo , Elizondo Guillermo
Published: October 2007

Cytochrome P-450 3A4 (CYP3A4) contributes to the metabolism of approximately half the drugs in clinical use today. The aim of the present study was to determine the frequency of the CYP3A4*1B, *2, *4, *5, and *18 alleles amongst both Tepehuan Amerindians, a native group that has inhabited northern Mexico for thousands of years, and Mestizo Mexicans, and to compare the data with those of other populations. Genotyping experiments revealed that 8.8 and 8.0% of the Mestizo and Tepehuano subjects, respectively, carried the CYP3A4*1B allele. Only one Mestizo subject was heterozygous for the CYP3A4*2 variant, while CYP3A4*4, *5 and *18 allelic variants were not detected in either group. On the other hand, the frequencies of the CYP3A4*1B variant in Mestizos and Tepehuanos were similar to those reported for Caucasians, but different from those observed for African and Asian populations.
Effect of Arsenic Trioxide on Uveal Melanoma Cell Proliferation in vitro
Authors: Wang Chunfang , Li Bin , Zhang Haiyan , Shi Guangpu , Li Weihong , Jonas Jost B.
Published: October 2007

Aims: The aim of this study was to investigate the effect of arsenic trioxide (ATO) on the growth of cultured uveal melanoma cells (OCM-1 cell line). Methods: Cultured OCM-1 cells were treated with 0.75–24 µM of ATO for 4–96 h. Cell viability was evaluated with the methylthiazoletetrazolium (MTT) assay as proliferation test. Apoptotic and necrotic cells were quantified using flow cytometry following Annexin-V/PI double stain. The cell morphology alteration was examined by light and electron transmission microscopy. To investigate the underlying mechanism of ATO-induced apoptosis and necrosis, glutathione peroxidase activity was measured, and mitochondrial membrane potentials were quantified using confocal microscopy. Results: In the MTT assays, OCM-1 cell growth was inhibited at ATO concentrations of 1.5–24 µM. The 50% inhibitory concentrationof ATO was 16.8 µM. At ATO concentrations of 12 and 24 µM, apoptosis and necrosis were induced after 24 h of incubation as shown by light and transmission electron microscopy. At ATO concentrations of 12 and 24 µM, the glutathione peroxidase activity was significantly (p < 0.05) reduced after 24 h of incubation, and the mitochondrial membrane potentials were significantly (p < 0.01) decreased after 4, 12 and 24 h of incubation. Conclusion: ATO inhibited ocular melanoma cell line growth at concentrations of 1.5–24 µM of ATO in a dose- and time-dependent manner by inducing apoptosis and necrosis of the tumor cells. The concurringly decreased glutathione peroxidase activity and the reduced mitochondrial membrane potentials may be possible underlying mechanisms for the apoptosis and necrosis of the tumor cells.
Acute Corneal Epithelial Change after Instillation of Benzalkonium Chloride Evaluated Using a Newly Developed in vivo Corneal Transepithelial Electric Resistance Measurement Method
Authors: Uematsu Masafumi , Kumagami Takeshi , Kusano Mao , Yamada Koki , Mishima Kazuaki , Fujimura Koichi , Sasaki Hitoshi , Kitaoka Takashi
Published: October 2007

Objective: Acute corneal permeability change after instillation of benzalkonium chloride (BAC) was evaluated using a newly developed in vivo corneal transepithelial electric resistance (TER) measurement method. Method: Corneal TER was measured by Ag/AgCl electrodes placed in the anterior aqueous chamber and on the cornea of live rabbit eyes. TER was measured and TER change after instillation of 0.05% BAC solution was monitored. After TER measurement, cornea was excised and fixed for transmission and scanning electron microscopy. For the control study, physiologic saline was used instead of BAC. Results: The TER of normal rabbit cornea was 602.3 ± 195.0 Ωcm2. TER decreased instantly after instillation of 0.05% BAC. In 5 s, TER decreased to 58.3 ± 5.2%. In 60 s, TER decreased to 18.5 ± 3.2%. At all time points, TER after instillation of 0.05% BAC was significantly lower than that of the control (p < 0.0001). Dissociation of tight junctions and the destruction of superficial cell membranes were observed under electron microscopy. Conclusion: Corneal epithelial change with increased permeability is rapid and intense after the instillation of highly concentrated BAC solution, accompanied by disorder of tight junctions and cell membranes of superficial cells. The newly developed in vivo corneal TER measurement method is suitable for assessing acute corneal change after drug instillation.
Expression of Matrix Metalloproteinases in Wound Healing after Glaucoma Filtration Surgery in Rabbits
Authors: Shima Ichirou , Katsuda Shogo , Ueda Yoshimichi , Takahashi Nobuo , Sasaki Hiroshi
Published: October 2007

Purpose: To investigate the protein and mRNA expressions of matrix metalloproteinases (MMPs), gelatinolytic activity and localization of MMP activity in wounds after glaucoma filtration surgery in rabbits. Methods: Sixty eyes of 30 rabbits were removed 1, 3, 7, 14 and 120 days after the surgery and used for this experiment. Protein and mRNA expressions were analyzed by immunohistochemistry and laser capture microdissection/real-time RT-PCR, respectively. The gelatinolytic activity was analyzed by gelatin zymography and the localization was studied using in situ zymography. Results: By immunohistochemistry, expression of MMP-1, MMP-2, MMP-3, MMP-9 and MT1-MMP was detected in the wounds, most markedly 3 days after the surgery. MMP-positive cells were predominantly macrophages. Expression of MMP-9 and MT1-MMP mRNAs was verified by RT-PCR. Gelatinolytic activities corresponding to proMMP-2 and the active form of MMP-2 were detected in the wounds 3 and 7 days after surgery. In situ zymography localized gelatinolytic activities at the wound site. These activities were almost completely abolished by an MMP inhibitor, indicating that the gelatinolytic activity belongs to metalloproteinases. Conclusions: MMPs, particularly MMP-2/MT1-MMP, play important roles in the degradation of the extracellular matrix in the wound healing process after glaucoma filtration surgery and may represent an important target for therapeutic intervention after glaucoma filtration surgery.
Full-Term Abdominal Pregnancy: A Case Report and Review of the Literature
Authors: Zhang Jianping , Li Fen , Sheng Qiu
Published: October 2007

Background: Abdominal pregnancy is a rare, life-threatening condition. Case: A 30-year-old pregnant, gravida 3, para 1, was presented to hospital at 38 weeks gestation. She suffered from abdominal pain at 16 weeks gestation. At admission, obstetrical examination and transabdominal ultrasonography revealed that it was uterine pregnancy with a single living fetus and oligohydramnios. The diagnosis of abdominal pregnancy was made till intrasurgical operation. An amniotomy was performed and a normal neonatal female was extracted as breech. A subtotal abdominal hysterectomy was conducted. No postoperative complications were observed. Conclusion: We present this case to call attention to the clinicians and ultrasonographers that it is always important to bear in mind the possibility of abdominal pregnancies especially in the condition of fetal malpresentation, history of abdominal pain, malformations or oligohydramnion.