24,963 research outputs found
No well-defined remnant Fermi surface in Sr2CuO2Cl2
In angle-resolved photoelectron spectra of the antiferromagnetic insulators
Ca2CuO2Cl2 and Sr2CuO2Cl2 a sharp drop of the spectral intensity of the
lowest-lying band is observed along a line in k space equivalent to the Fermi
surface of the optimally doped high-temperature superconductors. This was
interpreted as a signature of the existence of a remnant Fermi surface in the
insulating phase of the high-temperature superconductors. In this paper it is
shown that the drop of the spectral intensity is not related to the spectral
function but is a consequence of the electron-photon matrix elementComment: 4 pages, 3 figure
Improving green manure quality with phosphate rocks in Ontario Canada
Phosphate rock (PR) was applied to one conventional and two organic dairy fields and planted with buckwheat (Fagopyrum esculentum) as a green manure crop. In total, five types of PR were applied at three application rates in order to determine the yield, concentration of P in the aboveground tissue and the P uptake of buckwheat. It was found that PR of relatively high carbonate substitution and small particle diameter could increase buckwheat tissue concentrations to a quality such that mineralization of the buckwheat mulch could occur. Buckwheat mulch and residual PR increased soil P flux as determined by anion exchange membranes in situ in the following spring. This provides evidence that buckwheat of high P quality has the potential to supply P to a subsequent crop
Compression of Martian atmosphere for production of oxygen
The compression of CO2 from the Martian atmosphere for production of O2 via an electrochemical cell is addressed. Design specifications call for an oxygen production rate of 10 kg per day and for compression of 50 times that mass of CO2. Those specifications require a compression rate of over 770 cfm at standard Martian temperature and pressure (SMTP). Much of the CO2 being compressed represents waste, unless it can be recycled. Recycling can reduce the volume of gas that must be compressed to 40 cfm at SMTP. That volume reduction represents significant mass savings in the compressor, heating equipment, filters, and energy source. Successful recycle of the gas requires separation of CO (produced in the electrochemical cell) from CO2, N2, and Ar found in the Martian atmosphere. That aspect was the focus of this work
Comment on 'Non-equilibrium thermodynamics of light absorption'
A recent paper by Meszéna and Westerhoff (1999 J. Phys. A: Math. Gen. 32 301) has aimed to address what is referred to as a principal question of biological thermodynamics, the possibility of describing photosynthesis in terms of non-equilibrium thermodynamics. The issue is associated with a misrepresentation of the fundamental photophysics involved, and as a result the analysis is invalid
Experimental results of heat transfer and pressure drop of argon flowing through single tube with internal interrupted fins
Heat transfer and pressure drop of argon flowing through single tube with internal interrupted fin
The Influence of in-medium NN cross-sections, symmetry potential and impact parameter on the isospin observables
We explore the influence of in-medium nucleon-nucleon cross section, symmetry
potential and impact parameter on isospin sensitive observables in
intermediate-energy heavy-ion collisions with the ImQMD05 code, a modified
version of Quantum Molecular Dynamics model. At incident velocities above the
Fermi velocity, we find that the density dependence of symmetry potential plays
a more important role on the double neutron to proton ratio and the
isospin transport ratio than the in-medium nucleon-nucleon cross
sections, provided that the latter are constrained to a fixed total NN
collision rate. We also explore both and as a function of the
impact parameter. Since the copious production of intermediate mass fragments
is a distinguishing feature of intermediate-energy heavy-ion collisions, we
examine the isospin transport ratios constructed from different groups of
fragments. We find that the values of the isospin transport ratios for
projectile rapidity fragments with are greater than those constructed
from the entire projectile rapidity source. We believe experimental
investigations of this phenomenon can be performed. These may provide
significant tests of fragmentation time scales predicted by ImQMD calculations.Comment: 24 pages, 9 figures, to be published in Phys. Rev.
Transport Model Simulations of Projectile Fragmentation Reactions at 140 MeV/nucleon
The collisions in four different reaction systems using Ca and
Ni isotope beams and a Be target have been simulated using the Heavy
Ion Phase Space Exploration and the Antisymmetrized Molecular Dynamics models.
The present study mainly focuses on the model predictions for the excitation
energies of the hot fragments and the cross sections of the final fragments
produced in these reactions. The effects of various factors influencing the
final fragment cross sections, such as the choice of the statistical decay code
and its parameters have been explored. The predicted fragment cross sections
are compared to the projectile fragmentation cross sections measured with the
A1900 mass separator. At MeV, reaction dynamics can significantly
modify the detection efficiencies for the fragments and make them different
from the efficiencies applied to the measured data reported in the previous
work. The effects of efficiency corrections on the validation of event
generator codes are discussed in the context of the two models.Comment: 28 pages, 13 figure
Near-infrared Observations of Nova V574 Puppis (2004)
We present results obtained from extensive near-infrared spectroscopic and
photometric observations of nova V574 Pup during its 2004 outburst. The
observations were obtained over four months, starting from 2004 November 25
(four days after the nova outburst) to 2005 March 20. The near-IR JHK light
curve is presented - no evidence is seen from it for dust formation to have
occurred during our observations. In the early decline phase, the JHK spectra
of the nova are dominated by emission lines of hydrogen Brackett and Paschen
series, OI, CI and HeI. We also detect the fairly uncommon Fe II line at 1.6872
micron in the early part of our observations. The strengths of the HeI lines at
1.0830 micron and 2.0585 micron are found to become very strong towards the end
of the observations indicating a progression towards higher excitation
conditions in the nova ejecta. The width of the emission lines do not show any
significant change during the course of our observations. The slope of the
continuum spectrum was found to have a lambda^{-2.75} dependence in the early
stages which gradually becomes flatter with time and changes to a free-free
spectral dependence towards the later stages. Recombination analysis of the HI
lines shows deviations from Case B conditions during the initial stages.
However, towards the end of our observations, the line strengths are well
simulated with case B model values with electron density n_e = 10^{9-10}
cm^{-3} and a temperature equal to 10^4 K. Based on our distance estimate to
the nova of 5.5 kpc and the observed free-free continuum emission in the later
part of the observations, we estimate the ionized mass of the ejecta to be
between 10^{-5} and 10^{-6} solar-mass.Comment: 10 pages, 8 figures, Accepted for publication in MNRA
Tidal Datum Planes and Tidal Boundaries and Their Use as Legal Boundaries: A Study with Recommendations for Virginia
A synopsis of the frogs of the genus Eleutherodactylus from the Sierra Nevada de Santa Marta, Colombia
http://deepblue.lib.umich.edu/bitstream/2027.42/57147/1/OP711.pd
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