1,648 research outputs found

    Plasma-initiated polymerization and its applications

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    Plasma initiated polymerization is discussed. Topics include: polymerization of a vinyl monomer, solid phase polymerization, and inorganic ring compound polymers

    Event-by-event analysis of ultra-relativistic heavy-ion collisions in smoothed particle hydrodynamics

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    The method of smoothed particle hydrodynamics (SPH) is applied for ultra-relativistic heavy-ion collisions. The SPH method has several advantages in studying event-by-event fluctuations, which attract much attention in looking for quark gluon plasma (QGP) formation, because it gives a rather simple scheme for solving hydrodynamical equations. Using initial conditions for Au+Au collisions at RHIC energy produced by NeXus event generator, we solve the hydrodynamical equation in event-by-event basis and study the fluctuations of hadronic observables such as dN/dy due to the initial conditions. In particular, fluctuations of elliptic flow coefficient v2 is investigated for both the cases, with and without QGP formation. This can be used as an additional test of QGP formation.Comment: LaTeX, 16 figures, 3 tables, 23 pages. Talk presented at 6th International Workshop on Relativistic Aspects of Nuclear Physics(RANP2000), Caraguatatuba, Tabatinga Beach, Sao Paulo, Brazil, October 17-20, 2000. To be published in the proceedings (World Scientific, Singapore

    Event-by-event fluctuations in hydrodynamical description of heavy-ion collisions

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    Effects caused by the event-by-event fluctuation of the initial conditions in hydrodynamical description of high-energy heavy-ion collisions are investigated. Non-negligible effects appear for several observable quantities, even for a fixed impact parameter b⃗\vec b . They are sensitive to the equation of state, being the dispersions of the observable quantities in general smaller when the QGP phase appears at the beginning of hydrodynamic evolution than when the fluid remains hadron gas during whole the evolution.Comment: 4 pages, 4 figures, talk presented to Quark Matter 2001 Conferenc

    Analysis of Bose-Einstein correlations in e+e- -> W+W- events including final state interactions

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    Recently DELPHI Collaboration reported new data on Bose-Einstein correlations (BEC) measured in e+e- -> W^+W^- events. Apparently no enhancement has been observed. We have analyzed these data including final state interactions (FSI) of both Coulomb and strong (s-wave) origin and found that there is enhancement in BEC but it is overshadowed by the FSI which are extremely important for those events. We have found the following values for the size of the interaction range beta and the degree of coherence lambda: beta=0.87 +/- 0.31fm and lambda=1.19 +/- 0.48, respectively.Comment: 7pages, 4 figure

    Electronic Structure of Three-Dimensional Superlattices Subject to Tilted Magnetic Fields

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    Full quantum-mechanical description of electrons moving in 3D structures with unidirectional periodic modulation subject to tilted magnetic fields requires an extensive numerical calculation. To understand magneto-oscillations in such systems it is in many cases sufficient to use the quasi-classical approach, in which the zero-magnetic-field Fermi surface is considered as a magnetic-field-independent rigid body in k-space and periods of oscillations are related to extremal cross-sections of the Fermi surface cut by planes perpendicular to the magnetic-field direction. We point out cases where the quasi-classical treatment fails and propose a simple tight-binding fully-quantum-mechanical model of the superlattice electronic structure.Comment: 8 pages, 7 figures, RevTex, submitted to Phys. Rev.

    Coulomb Effect: A Possible Probe for the Evolution of Hadronic Matter

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    Electromagnetic field produced in high-energy heavy-ion collisions contains much useful information, because the field can be directly related to the motion of the matter in the whole stage of the reaction. One can divide the total electromagnetic field into three parts, i.e., the contributions from the incident nuclei, non-participating nucleons and charged fluid, the latter consisting of strongly interacting hadrons or quarks. Parametrizing the space-time evolution of the charged fluid based on hydrodynamic model, we study the development of the electromagnetic field which accompanies the high-energy heavy-ion collisions. We found that the incident nuclei bring a rather strong electromagnetic field to the interaction region of hadrons or quarks over a few fm after the collision. On the other hand, the observed charged hadrons' spectra are mostly affected (Coulomb effect) by the field of the charged fluid. We compare the result of our model with experimental data and found that the model reproduces them well. The pion yield ratio pi^-/pi+ at a RHIC energy, Au+Au 100+100 GeV/nucleon, is also predicted.Comment: 23 pages, RevTex, 19 eps figures, revised versio

    2-D constrained Navier-Stokes equation and intermediate asymptotics

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    We introduce a modified version of the two-dimensional Navier-Stokes equation, preserving energy and momentum of inertia, which is motivated by the occurrence of different dissipation time scales and related to the gradient flow structure of the 2-D Navier-Stokes equation. The hope is to understand intermediate asymptotics. The analysis we present here is purely formal. A rigorous study of this equation will be done in a forthcoming paper

    Physiological aspects of the determination of comprehensive arterial inflows in the lower abdomen assessed by Doppler ultrasound

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    Non-invasive measurement of splanchnic hemodynamics has been utilized in the clinical setting for diagnosis of gastro-intestinal disease, and for determining reserve blood flow (BF) distribution. However, previous studies that measured BF in a "single vessel with small size volume", such as the superior mesenteric and coeliac arteries, were concerned solely with the target organ in the gastrointestinal area, and therefore evaluation of alterations in these single arterial BFs under various states was sometimes limited to "small blood volumes", even though there was a relatively large change in flow. BF in the lower abdomen (BFAb) is potentially a useful indicator of the influence of comprehensive BF redistribution in cardiovascular and hepato-gastrointestinal disease, in the postprandial period, and in relation to physical exercise. BFAb can be determined theoretically using Doppler ultrasound by subtracting BF in the bilateral proximal femoral arteries (FAs) from BF in the upper abdominal aorta (Ao) above the coeliac trunk. Prior to acceptance of this method of determining a true BFAb value, it is necessary to obtain validated normal physiological data that represent the hemodynamic relationship between the three arteries. In determining BFAb, relative reliability was acceptably high (range in intra-class correlation coefficient: 0.85-0.97) for three arterial hemodynamic parameters (blood velocity, vessel diameter, and BF) in three repeated measurements obtained over three different days. Bland-Altman analysis of the three repeated measurements revealed that day-to-day physiological variation (potentially including measurement error) was within the acceptable minimum range (95% of confidence interval), calculated as the difference in hemodynamics between two measurements. Mean BF (ml/min) was 2951 ± 767 in Ao, 316 ± 97 in left FA, 313 ± 83 in right FA, and 2323 ± 703 in BFAb, which is in agreement with a previous study that measured the sum of BF in the major part of the coeliac, mesenteric, and renal arteries. This review presents the methodological concept that underlies BFAb, and aspects of its day-to-day relative reliability in terms of the hemodynamics of the three target arteries, relationship with body surface area, respiratory effects, and potential clinical usefulness and application, in relation to data previously reported in original dedicated research

    TXNDC5, a newly discovered disulfide isomerase with a key role in cell physiology and pathology

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    Thioredoxin domain-containing 5 (TXNDC5) is a member of the protein disulfide isomerase family, acting as a chaperone of endoplasmic reticulum under not fully characterized conditions As a result, TXNDC5 interacts with many cell proteins, contributing to their proper folding and correct formation of disulfide bonds through its thioredoxin domains. Moreover, it can also work as an electron transfer reaction, recovering the functional isoform of other protein disulfide isomerases, replacing reduced glutathione in its role. Finally, it also acts as a cellular adapter, interacting with the N-terminal domain of adiponectin receptor. As can be inferred from all these functions, TXNDC5 plays an important role in cell physiology; therefore, dysregulation of its expression is associated with oxidative stress, cell ageing and a large range of pathologies such as arthritis, cancer, diabetes, neurodegenerative diseases, vitiligo and virus infections. Its implication in all these important diseases has made TXNDC5 a susceptible biomarker or even a potential pharmacological target
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