2,517 research outputs found
Initial Condition for QGP Evolution from NEXUS
We recently proposed a new approach to high energy nuclear scattering, which
treats the initial stage of heavy ion collisions in a sophisticated way.
We are able to calculate macroscopic quantities like energy density and
velocity flow at the end of this initial stage, after the two nuclei having
penetrated each other.
In other words, we provide the initial conditions for a macroscopic treatment
of the second stage of the collision.
We address in particular the question of how to incorporate the soft
component properly. We find almost perfect "Bjorken scaling": the rapidity
coincides with the space-time rapidity, whereas the transverse flow is
practically zero. The distribution of the energy density in the transverse
plane shows typically a very "bumpy" structure.Comment: 17 pages, 24 figure
The centrality dependence of v2/epsilon: the ideal hydro limit and eta/s
The large elliptic flow observed at RHIC is considered to be evidence for
almost perfect liquid behavior of the strongly coupled quark-gluon plasma
produced in the collisions. In these proceedings we present a two parameter fit
for the centrality dependence of the elliptic flow scaled by the spatial
eccentricity. We show by comparing to viscous hydrodynamical calculations that
these two parameters are in good approximation proportional to the shear
viscosity over entropy ratio and the ideal hydro limit of the ratio v2/epsilon.Comment: 4 pages, 8 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee - final version
without line number
Gd(III)-Gd(III) Relaxation-Induced Dipolar Modulation Enhancement for In-Cell Electron Paramagnetic Resonance Distance Determination
In-cell distance determination by electron paramagnetic resonance (EPR) spectroscopy reveals essential structural information about biomacromolecules under native conditions. We demonstrate that the pulsed EPR technique RIDME (relaxation induced dipolar modulation enhancement) can be utilized for such distance determination. The performance of in-cell RIDME has been assessed at Q-band using stiff molecular rulers labeled with Gd(III)-PyMTA and microinjected into Xenopus laevis oocytes. The overtone coefficients are determined to be the same for protonated aqueous solutions and inside cells. As compared to in-cell DEER (double electron-electron resonance, also abbreviated as PELDOR), in-cell RIDME features approximately 5 times larger modulation depth and does not show artificial broadening in the distance distributions due to the effect of pseudosecular terms
Influence of Low Energy Hadronic Interactions on Air-shower Simulations
Experiments measuring cosmic rays above an energy of 10^14 eV deduce the
energy and mass of the primary cosmic ray particles from air-shower
simulations. We investigate the importance of hadronic interactions at low and
high energies on the distributions of muons and electrons in showers on ground.
In air shower simulation programs, hadronic interactions below an energy
threshold in the range from 80 GeV to 500 GeV are simulated by low energy
interaction models, like Fluka or Gheisha, and above that energy by high energy
interaction models, e.g. Sibyll or QGJSJet. We find that the impact on shower
development obtained by switching the transition energy from 80 GeV to 500 GeV
is comparable to the difference obtained by switching between Fluka and
Gheisha.Comment: 4 pages, 6 figures, ISVHECRI 200
Ensuring health and food safety from rapidly expanding wastewater irrigation in South Asia: BMZ final report 2005-2008
Wastewater irrigation / Institutions / Public health / Health hazards / Diseases / Cropping systems / Vegetables / Fodder / Livestock / Risk assessment / Economic evaluation / Surveys / GIS / Research priorities / South Asia / India / Pakistan / Hyderabad / Faisalabad / Musi River
Oscillatory Flows Induced by Microorganisms Swimming in Two-dimensions
We present the first time-resolved measurements of the oscillatory velocity
field induced by swimming unicellular microorganisms. Confinement of the green
alga C. reinhardtii in stabilized thin liquid films allows simultaneous
tracking of cells and tracer particles. The measured velocity field reveals
complex time-dependent flow structures, and scales inversely with distance. The
instantaneous mechanical power generated by the cells is measured from the
velocity fields and peaks at 15 fW. The dissipation per cycle is more than four
times what steady swimming would require.Comment: 4 pages, 4 figure
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