2,632 research outputs found
Sustainable Water Management in the Southwestern United States: Reality or Rhetoric?
Background: While freshwater sustainability is generally defined as the provisioning of water for both people and the environment, in practice it is largely focused only on supplying water to furnish human population growth. Symptomatic of this is the state of Arizona, where rapid growth outside of the metropolitan Phoenix-Tucson corridor relies on the same groundwater that supplies year-round flow in rivers. Using Arizona as a case study, we present the first study in the southwestern United States that evaluates the potential impact of future population growth and water demand on streamflow depletion across multiple watersheds. Methodology/Principal Findings: We modeled population growth and water demand through 2050 and used four scenarios to explore the potential effects of alternative growth and water management strategies on river flows. Under the base population projection, we found that rivers in seven of the 18 study watersheds could be dewatered due to municipal demand. Implementing alternative growth and water management strategies, however, could prevent four of these rivers from being dewatered. Conclusions/Significance: The window of opportunity to implement water management strategies is narrowing. Because impacts from groundwater extraction are cumulative and cannot be immediately reversed, proactive water management strategies should be implemented where groundwater will be used to support new municipal demand. Our approach provides a low-cost method to identify where alternative water and growth management strategies may have the most impact, and demonstrates that such strategies can maintain a continued water supply for both people and the environment
Beam Performance of Tracking Detectors with Industrially Produced GEM Foils
Three Gas-Electron-Multiplier tracking detectors with an active area of 10 cm
x 10 cm and a two-dimensional, laser-etched orthogonal strip readout have been
tested extensively in particle beams at the Meson Test Beam Facility at
Fermilab. These detectors used GEM foils produced by Tech-Etch, Inc. They
showed an efficiency in excess of 95% and spatial resolution better than 70 um.
The influence of the angle of incidence of particles on efficiency and spatial
resolution was studied in detail.Comment: 8 pages, 9 figures, accepted by Nuclear Instruments and Methods in
Physics Research
Laboratory Tests of Low Density Astrophysical Equations of State
Clustering in low density nuclear matter has been investigated using the
NIMROD multi-detector at Texas A&M University. Thermal coalescence modes were
employed to extract densities, , and temperatures, , for evolving
systems formed in collisions of 47 MeV Ar + Sn,Sn
and Zn + Sn, Sn. The yields of , , He, and
He have been determined at = 0.002 to 0.032 nucleons/fm and
= 5 to 10 MeV. The experimentally derived equilibrium constants for
particle production are compared with those predicted by a number of
astrophysical equations of state. The data provide important new constraints on
the model calculations.Comment: 5 pages, 3 figure
Nuclear Multifragmentation in the Non-extensive Statistics - Canonical Formulation
We apply the canonical quantum statistical model of nuclear
multifragmentation generalized in the framework of recently proposed Tsallis
non-extensive thermostatistics for the description of nuclear
multifragmentation process. The test calculation in the system with A=197
nucleons show strong modification of the 'critical' behaviour associated with
the nuclear liquid-gas phase transition for small deviations from the
conventional Boltzmann-Gibbs statistical mechanics.Comment: 4 pages, 4 figure
Experimental Determination of In-Medium Cluster Binding Energies and Mott Points in Nuclear Matter
In medium binding energies and Mott points for , , He and
clusters in low density nuclear matter have been determined at specific
combinations of temperature and density in low density nuclear matter produced
in collisions of 47 MeV Ar and Zn projectiles with Sn
and Sn target nuclei. The experimentally derived values of the in
medium modified binding energies are in good agreement with recent theoretical
predictions based upon the implementation of Pauli blocking effects in a
quantum statistical approach.Comment: 5 pages, 3 figure
Centrality dependence of charged-particle pseudorapidity distributions from d+Au collisions at sqrt(s_{NN})=200 GeV
Charged-particle pseudorapidity densities are presented for the d+Au reaction
at sqrt{s_{NN}}=200 GeV with -4.2 <= eta <= 4.2$. The results, from the BRAHMS
experiment at RHIC, are shown for minimum-bias events and 0-30%, 30-60%, and
60-80% centrality classes. Models incorporating both soft physics and hard,
perturbative QCD-based scattering physics agree well with the experimental
results. The data do not support predictions based on strong-coupling,
semi-classical QCD. In the deuteron-fragmentation region the central 200 GeV
data show behavior similar to full-overlap d+Au results at sqrt{s_{NN}}=19.4
GeV.Comment: 4 pages, 3figures; expanded discussion of uncertainties; added 60-80%
centrality range; added additional discussion on centrality selection bia
Scanning the phases of QCD with BRAHMS
BRAHMS has the ability to study relativistic heavy ion collisions from the
final freeze-out of hadrons all the way back to the initial wave-function of
the gold nuclei. This is accomplished by studying hadrons with a very wide
range of momenta and angles. In doing so we can scan various phases of QCD,
from a hadron gas, to a quark gluon plasma and perhaps to a color glass
condensate.Comment: 8 pages, 6 figures, proceedings of plenary talk at Quark Matter 2004
conferenc
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