Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 26
Filter
Add more filters








Publication year range
1.
Phys Rev Lett ; 104(14): 142301, 2010 Apr 09.
Article in English | MEDLINE | ID: mdl-20481933

ABSTRACT

This Letter presents the first measurement of event-by-event fluctuations of the elliptic flow parameter v(2) in Au+Au collisions at square root(s(NN))=200 GeV as a function of collision centrality. The relative nonstatistical fluctuations of the v(2) parameter are found to be approximately 40%. The results, including contributions from event-by-event elliptic flow fluctuations and from azimuthal correlations that are unrelated to the reaction plane (nonflow correlations), establish an upper limit on the magnitude of underlying elliptic flow fluctuations. This limit is consistent with predictions based on spatial fluctuations of the participating nucleons in the initial nuclear overlap region. These results provide important constraints on models of the initial state and hydrodynamic evolution of relativistic heavy ion collisions.

2.
Phys Rev Lett ; 104(6): 062301, 2010 Feb 12.
Article in English | MEDLINE | ID: mdl-20366815

ABSTRACT

A measurement of two-particle correlations with a high transverse momentum trigger particle (p(T)(trig) > 2.5 GeV/c) is presented for Au+Au collisions at square root(s(NN)) = 200 GeV over the uniquely broad longitudinal acceptance of the PHOBOS detector (-4 < Delta eta < 2). A broadening of the away-side azimuthal correlation compared to elementary collisions is observed at all Delta eta. As in p+p collisions, the near side is characterized by a peak of correlated partners at small angle relative to the trigger particle. However, in central Au+Au collisions an additional correlation extended in Delta eta and known as the "ridge" is found to reach at least |Delta eta| approximately = 4. The ridge yield is largely independent of Delta eta over the measured range, and it decreases towards more peripheral collisions. For the chosen (p(T)(trig) cut, the ridge yield is consistent with zero for events with less than roughly 100 participating nucleons.

3.
Phys Rev Lett ; 102(14): 142301, 2009 Apr 10.
Article in English | MEDLINE | ID: mdl-19392428

ABSTRACT

We present the first measurements of the pseudorapidity distribution of primary charged particles in Cu+Cu collisions as a function of collision centrality and energy, sqrt[s_{NN}]=22.4, 62.4, and 200 GeV, over a wide range of pseudorapidity, using the PHOBOS detector. A comparison of Cu+Cu and Au+Au results shows that the total number of produced charged particles and the rough shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants. More detailed studies reveal that a more precise matching of the shape of the Cu+Cu and Au+Au pseudorapidity distributions over the full range of pseudorapidity occurs for the same N{part}/2A rather than the same N_{part}. In other words, it is the collision geometry rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence at RHIC energies.

4.
Phys Rev Lett ; 98(24): 242302, 2007 Jun 15.
Article in English | MEDLINE | ID: mdl-17677957

ABSTRACT

This Letter presents measurements of the elliptic flow of charged particles as a function of pseudorapidity and centrality from Cu-Cu collisions at 62.4 and 200 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider. The elliptic flow in Cu-Cu collisions is found to be significant even for the most central events. For comparison with the Au-Au results, it is found that the detailed way in which the collision geometry (eccentricity) is estimated is of critical importance when scaling out system-size effects. A new form of eccentricity, called the participant eccentricity, is introduced which yields a scaled elliptic flow in the Cu-Cu system that has the same relative magnitude and qualitative features as that in the Au-Au system.

5.
Akush Ginekol (Sofiia) ; 46 Suppl 1: 73-80, 2007.
Article in Bulgarian | MEDLINE | ID: mdl-18173019

ABSTRACT

The aim of this study is to evaluate the application of phospholipid liposomes in HCl--induced RDS in rabbits. Acute respiratory distress syndrome was induced by administration of 0.2 N HCl via intratracheal instillation for 45 min. After induced ARDS animals under artificial lung ventilation were retreated with liposomes for 60 min. Arterial blood gas analysis was performed at 30, 45 and 60 min after liposome application. Untreated animals were ventilated for the same time. Rabbits were killed with thiopental and bronhoalveolar lavage fluid biochemical and biophysical parameters were investigated. HCl- lung injury caused decrease of arterial oxygen pressure/ fraction of inspired oxygen ratio more than 50% compared to the control. We obtained high respiratory acidosis as well. The instillation of liposomes led to reversion of gas exchange at 60 min. after application almost to the control value. In order to characterize the rabbit lung tissue changes after HCl-treatment histological and ultra thin slices were obtained. Electron microscopic preparations demonstrate disappearance of surface active film in treated animals. Application of liposomes led to visualization of osmophilic material forming lamellae in lamellar bodies. On the basis of the results obtained we may assume that it is likely that the liposomes assessed in this study might be used for in vivo improvement of oxygenation in acid aspiration induced ARDS.


Subject(s)
Acidosis, Respiratory/etiology , Lung/drug effects , Phospholipids/therapeutic use , Respiratory Distress Syndrome/drug therapy , Acidosis, Respiratory/blood , Animals , Biophysical Phenomena , Biophysics , Blood Gas Analysis , Bronchoalveolar Lavage Fluid/chemistry , Disease Models, Animal , Liposomes , Lung/ultrastructure , Male , Microscopy, Electron , Phospholipids/administration & dosage , Rabbits , Respiratory Distress Syndrome/blood , Respiratory Distress Syndrome/complications , Respiratory Distress Syndrome/pathology
6.
Akush Ginekol (Sofiia) ; 46 Suppl 1: 29-36, 2007.
Article in Bulgarian | MEDLINE | ID: mdl-18175392

ABSTRACT

Surfactant therapy leads to significant clinical improvement in infants at risk for, or having, respiratory distress syndrome (RDS). The development of exogenous surfactant (ES) as a therapy for neonatal respiratory disorders was a significant advance in neonatal intensive care that has led to a decrease in neonatal mortality. Two broad categories of surfactants are available for exogenous therapy: surfactants derived from animal sources or 'natural' surfactants; and synthetic surfactants. The physical properties of natural and synthetic surfactants have been studied using techniques such as the Wilhelmy surface balance and the bilayer black film (BBF) method. Here we report some data from a comparative study of ES (Exosurf, Survanta, Curosurf and Alveofact) and clinical samples of tracheal aspirate (TA) of newborns with RDS treated with Curosurf. Measured interfacial physico-chemical parameters prove "better" properties in vitro of the surfactant proteins (SP-B and SP-C) containing preparations Curosurf and Alveofact. Their properties are similar, Alveofact showing a higher surface tension lowering capacity under dynamic conditions. A compendious comparison of results for dynamic surface properties of monolayers of TA from newborns treated with Curosurf with data for newborns treated with Exosurf is presented. Both ES yield the desired lowering of the surface tension during cyclic film compression, being larger after treatment with Curosurf. Observations concerning the properties of BFF of ES (dependence on surfactant concentration, adsorption time, film drainage time and BFF formation time) are also reported and discussed.


Subject(s)
Models, Biological , Pulmonary Surfactants , Respiratory Distress Syndrome, Newborn/drug therapy , Animals , Biological Products/chemistry , Biological Products/pharmacology , Biological Products/therapeutic use , Biophysical Phenomena , Biophysics , Drug Combinations , Fatty Alcohols/chemistry , Fatty Alcohols/pharmacology , Fatty Alcohols/therapeutic use , Humans , Infant, Newborn , Lipids/chemistry , Lipids/pharmacology , Lipids/therapeutic use , Phospholipids/chemistry , Phospholipids/pharmacology , Phospholipids/therapeutic use , Phosphorylcholine/chemistry , Phosphorylcholine/pharmacology , Phosphorylcholine/therapeutic use , Polyethylene Glycols/chemistry , Polyethylene Glycols/pharmacology , Polyethylene Glycols/therapeutic use , Pulmonary Surfactants/chemistry , Pulmonary Surfactants/pharmacology , Pulmonary Surfactants/therapeutic use , Respiratory Distress Syndrome, Newborn/metabolism , Surface Tension/drug effects
7.
Phys Rev Lett ; 97(1): 012301, 2006 Jul 07.
Article in English | MEDLINE | ID: mdl-16907368

ABSTRACT

We report on measurements of directed flow as a function of pseudorapidity in Au + Au collisions at energies of square root of SNN = 19.6, 62.4, 130 and 200 GeV as measured by the PHOBOS detector at the BNL Relativistic Heavy Ion Collider. These results are particularly valuable because of the extensive, continuous pseudorapidity coverage of the PHOBOS detector. There is no significant indication of structure near midrapidity and the data surprisingly exhibit extended longitudinal scaling similar to that seen for elliptic flow and charged particle pseudorapidity density.

8.
Phys Rev Lett ; 96(21): 212301, 2006 Jun 02.
Article in English | MEDLINE | ID: mdl-16803231

ABSTRACT

We present transverse momentum distributions of charged hadrons produced in Cu + Cu collisions at square root of SNN = 62.4 and 200 GeV. The spectra are measured for transverse momenta of 0.25 < pT < 5.0 GeV/c at square root of SNN = 62.4 GeV and 0.25 < pT < 7.0 GeV/c at square root of SNN = 200 GeV, in a pseudorapidity range of 0.2 < eta < 1.4. The nuclear modification factor R(AA) is calculated relative to p + p data at both collision energies as a function of collision centrality. At a given collision energy and fractional cross section, R(AA) is observed to be systematically larger in Cu + Cu collisions compared to Au + Au. However, for the same number of participating nucleons, R(AA) is essentially the same in both systems over the measured range of pT, in spite of the significantly different geometries of the Cu + Cu and Au + Au systems.

9.
Phys Rev Lett ; 94(12): 122303, 2005 Apr 01.
Article in English | MEDLINE | ID: mdl-15903910

ABSTRACT

This Letter describes the measurement of the energy dependence of elliptic flow for charged particles in Au+Au collisions using the PHOBOS detector at the Relativistic Heavy Ion Collider. Data taken at collision energies of square root of s(NN)=19.6, 62.4, 130, and 200 GeV are shown over a wide range in pseudorapidity. These results, when plotted as a function of eta(')=|eta|-y(beam), scale with approximate linearity throughout eta('), implying no sharp changes in the dynamics of particle production as a function of pseudorapidity or increasing beam energy.

11.
Phys Rev Lett ; 93(8): 082301, 2004 Aug 20.
Article in English | MEDLINE | ID: mdl-15447175

ABSTRACT

The measured pseudorapidity distribution of primary charged particles in minimum-bias d+Au collisions at sqrt[s(NN)]=200 GeV is presented for the first time. This distribution falls off less rapidly in the gold direction as compared to the deuteron direction. The average value of the charged particle pseudorapidity density at midrapidity is |eta|< or =0.6)=9.4+/-0.7(syst) and the integrated primary charged particle multiplicity in the measured region is 82+/-6(syst). Estimates of the total charged particle production, based on extrapolations outside the measured pseudorapidity region, are also presented. The pseudorapidity distribution, normalized to the number of participants in d+Au collisions, is compared to those of Au+Au and p+(-)p systems at the same energy. The d+Au distribution is also compared to the predictions of the parton saturation model, as well as microscopic models.

13.
Phys Rev Lett ; 91(5): 052303, 2003 Aug 01.
Article in English | MEDLINE | ID: mdl-12906591

ABSTRACT

We present measurements of the pseudorapidity distribution of primary charged particles produced in Au+Au collisions at three energies, sqrt[s(NN)]=19.6, 130, and 200 GeV, for a range of collision centrali-ties. The distribution narrows for more central collisions and excess particles are produced at high pseudorapidity in peripheral collisions. For a given centrality, however, the distributions are found to scale with energy according to the "limiting fragmentation" hypothesis. The universal fragmentation region described by this scaling grows in pseudorapidity with increasing collision energy, extending well away from the beam rapidity and covering more than half of the pseudorapidity range over which particles are produced. This approach to a universal limiting curve appears to be a dominant feature of the pseudorapidity distribution and therefore of the total particle production in these collisions.

14.
Phys Rev Lett ; 89(22): 222301, 2002 Nov 25.
Article in English | MEDLINE | ID: mdl-12485063

ABSTRACT

This paper describes the measurement of collective flow for charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0

15.
Phys Rev Lett ; 88(2): 022302, 2002 Jan 14.
Article in English | MEDLINE | ID: mdl-11801006

ABSTRACT

We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at root square[s(NN)] = 200 GeV. For the 6% most central collisions, we obtain dN(ch)/d(eta)/(/eta/<1) = 650+/-35(syst). Compared to collisions at root square[s(NN)] = 130 GeV, the highest energy studied previously, an increase by a factor of 1.14+/-0.05 at 90% confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.

17.
Klin Khir ; (6): 13-5, 2000 Jun.
Article in Russian | MEDLINE | ID: mdl-11288267

ABSTRACT

The results of treatment of 63 injured persons with thoracicoabdominal trauma were analyzed. Injured persons with severe trauma and pronounced infringements of hemodynamic (41.25%); with severe injury of inferior organs and stable hemodynamical indexes (47.62%), light injury (11.12%) were detailed. Algorithm of curative-diagnostical measures for every group was elaborated. Among the injured persons 11 (17.46%) died.


Subject(s)
Abdominal Injuries/epidemiology , Abdominal Injuries/surgery , Thoracic Injuries/epidemiology , Thoracic Injuries/surgery , Abdominal Injuries/diagnosis , Adolescent , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Thoracic Injuries/diagnosis , Treatment Outcome
18.
Antibiot Khimioter ; 41(4): 44-50, 1996 Apr.
Article in Russian | MEDLINE | ID: mdl-8967810

ABSTRACT

Multifactor analysis of the lomefloxacin effect on the primary immune response to T-independent bacterial antigen (vaccine EV fraction 1) and to T-dependent cellular antigen (SRBC) in mice was performed with the use of a wide range of the antibiotic concentrations and the dosage time. It was shown that lomefloxacin in the doses corresponding to the average therapeutic ones used for 3-9 days had no effect on the content of the IgG antibodies, was able to increase the level of the IgM antibodies and insignificantly lowered the concentration of the IgA antibodies.


Subject(s)
Anti-Infective Agents/pharmacology , Antigens, Bacterial/immunology , Fluoroquinolones , Hemagglutinins/immunology , Immunoglobulins/biosynthesis , Quinolones/pharmacology , Animals , Erythrocytes/immunology , Immunization , Immunoglobulin A/biosynthesis , Immunoglobulin G/biosynthesis , Immunoglobulin M/biosynthesis , Mice , Sheep
19.
Antibiot Khimioter ; 41(1): 3-6, 1996 Jan.
Article in Russian | MEDLINE | ID: mdl-8762817

ABSTRACT

The in vitro effect of lomefloxacin within the wide dose ranges from 0.1 to 100 micrograms/ml on luminol-dependent chemiluminescence and adherence of polymorphonuclear leukocytes of guinea pigs was studied under two different conditions: during the cell incubation in the presence of various concentrations of the drug and after the cell washing to remove lomefloxacin. In concentrations of 10 and 100 micrograms/ml the drug inhibited the response under the both conditions while in a concentration of 1 microgram/ml it stimulated the chemiluminescence. In concentrations of 0.1 to 100 micrograms/ml lomefloxacin stimulated the leukocyte adherence. The highest stimulation was observed with the use of the drug in a concentration of 1 microgram/ml.


Subject(s)
Anti-Infective Agents/pharmacology , Fluoroquinolones , Leukocytes/drug effects , Luminol/pharmacology , Quinolones/pharmacology , Animals , Cell Adhesion/drug effects , Guinea Pigs , Leukocytes/cytology , Luminescent Measurements
SELECTION OF CITATIONS
SEARCH DETAIL