12,610 research outputs found
A method of solving sets of nonlinear algebraic equations Progress report
Methods for solving nonlinear algebraic equations in computer programs for nuclear magnetic resonance spectroscop
Evaluation of the Axial Vector Commutator Sum Rule for Pion-Pion Scattering
We consider the sum rule proposed by one of us (SLA), obtained by taking the
expectation value of an axial vector commutator in a state with one pion. The
sum rule relates the pion decay constant to integrals of pion-pion cross
sections, with one pion off the mass shell. We remark that recent data on
pion-pion scattering allow a precise evaluation of the sum rule. We also
discuss the related Adler--Weisberger sum rule (obtained by taking the
expectation value of the same commutator in a state with one nucleon),
especially in connection with the problem of extrapolation of the pion momentum
off its mass shell. We find, with current data, that both the pion-pion and
pion-nucleon sum rules are satisfied to better than six percent, and we give
detailed estimates of the experimental and extrapolation errors in the closure
discrepancies.Comment: Plain TeX file;minor changes; version to be published in Pys. Rev. D;
corrected refs.12,1
Black Extended Objects, Naked Singularities and P-Branes
We treat the horizons of charged, dilaton black extended objects as quantum
mechanical objects. We show that the S matrix for such an object can be written
in terms of a p-brane-like action. The requirements of unitarity of the S
matrix and positivity of the p-brane tension equivalent severely restrict the
number of space-time dimensions and the allowed values of the dilaton parameter
a. Generally, black objects transform at the extremal limit into p-branes.Comment: 9 pages, REVTE
A relationship between the integrated CO intensity and the radio continuum emission in spiral galaxies
In an effort to determine the role played by cosmic ray electrons and interstellar radiation fields on the collapse of molecular clouds, a survey was begun to investigate the relationship between the radio continuum brightness emission and the integrated CO intensity in spiral galaxies. The investigation was done on two scales; a global galaxy to galaxy comparison of integrated disk values, and a ring-averaged study over the disks of individual galaxies. For the large-scale survey, radio continuum flux densities integrated over the full disk at 1.49 GHz were taken from Condon (1987) and the total CO fluxes were taken from Verter (1985). The galaxies with values included in the two catalogs are displayed. It can be seen that a good correlation exists between the integrated CO emission and radio continuum emission
A high resolution CO map of M51
Observations of the CO (1-0) emission in two fields of M51 were taken with the Berkeley-Illinois-Maryland Array at Hat Creek, California from May 1988 to February 1989. When combined with two previously observed fields (Lo et al. 1988), a complete map of the central 5 minute x 4 minute at a resolution of 7 seconds x 10 seconds was obtained. The project is part of an ongoing high-resolution survey of the molecular, atomic, and ionized gas distributions in nearby spiral galaxies. The two recently observed fields can be compared to the results of the interferometric study of Vogel et al. (1988 - hereafter VKS). Since the shortest spacing in the current survey is shorter than that of VKS, researchers expect to see more of the extended emission. This is evident when comparing the width of the spiral arms in each survey; ours are a bit broader. While some of the peaks in this region correspond to the peaks in VKS, several of them do not. These discrepancies are probably because of the low signal to noise inherent in observations of this nature. Single-dish maps are currently being readied for inclusion with the interferometer data. These will help fill the short-spacing hole in the UV plane, and serve to recover the flux missing from the interferometer maps
Muon Spectra of Quasi-Elastic and 1-Pion Production Events in LBL Neutrino Oscillation Experiments
The muon energy spectra of the quasi-elastic and 1-pion production events in
a LBL experiment, like K2K, are predicted to follow closely the neutrino energy
spectrum, with downward shifts of the energy scale by and respectively. These predictions seem to agree with the
observed muon spectra in the K2K nearby detector. The corresponding muon
spectra in the far-away (SK) detector are predicted to show characteristic
spectral distortions induced by oscillation. Comparison of the
predicted spectral distortions with the observed muon spectra of the 1-Ring and
2-Ring muon events in the SK detector will help to determine the oscillation
parameters. The results will be applicable to other LBL experiments as well.Comment: 13 pages. One figure and a few comments added, final version to
appear in P
Radiative and Collisional Energy Loss, and Photon-Tagged Jets at RHIC
The suppression of single jets at high transverse momenta in a quark-gluon
plasma is studied at RHIC energies, and the additional information provided by
a photon tag is included. The energy loss of hard jets traversing through the
medium is evaluated in the AMY formalism, by consistently taking into account
the contributions from radiative events and from elastic collisions at leading
order in the coupling. The strongly-interacting medium in these collisions is
modelled with (3+1)-dimensional ideal relativistic hydrodynamics. Putting these
ingredients together with a complete set of photon-production processes, we
present a calculation of the nuclear modification of single jets and
photon-tagged jets at RHIC.Comment: 4 pages, 4 figures, contributed to the 3rd International Conference
on Hard and Electro-Magnetic Probes of High-Energy Nuclear Collisions (Hard
Probes 2008), typos corrected, published versio
Evolution of magnetic component in Yang-Mills condensate dark energy models
The evolution of the electric and magnetic components in an effective
Yang-Mills condensate dark energy model is investigated. If the electric field
is dominant, the magnetic component disappears with the expansion of the
Universe. The total YM condensate tracks the radiation in the earlier Universe,
and later it becomes thus is similar to the cosmological constant.
So the cosmic coincidence problem can be avoided in this model. However, if the
magnetic field is dominant, holds for all time, suggesting that it
cannot be a candidate for the dark energy in this case.Comment: 12 pages, 4 figures, minor typos correcte
Reduction of Soil-Borne Plant Pathogens Using Lime and Ammonia Evolved from Broiler Litter
In laboratory and micro-plots simulations and in a commercial greenhouse, soil ammonia (NH3) and pH were manipulated as means to control soil-borne fungal pathogens and nematodes. Soil ammonification capacity was increased by applying low C/N ratio broiler litter at 1–8% (w/w). Soil pH was increased using lime at 0.5–1% (w/w). This reduced fungi (Fusarium oxysporum f. sp. dianthi and Sclerotium rolfsii) and root-knot nematode (Meloidogyne javanica) in lab tests below detection. In a commercial greenhouse, broiler litter (25 Mg ha−1) and lime (12.5 Mg ha−1) addition to soil in combination with solarization significantly reduced M. javanica induced root galling of tomato test plants from 47% in the control plots (solarization only) to 7% in treated plots. Root galling index of pepper plants, measured 178 days after planting in the treated and control plots, were 0.8 and 1.5, respectively, which was statistically significantly different. However, the numbers of nematode juveniles in the root zone soil counted 83 and 127 days after pepper planting were not significantly different between treatments. Pepper fruit yield was not different between treatments. Soil disinfection and curing was completed within one month, and by the time of bell-pepper planting the pH and ammonia values were normal
A constructive approach to the soliton solutions of integrable quadrilateral lattice equations
Scalar multidimensionally consistent quadrilateral lattice equations are
studied. We explore a confluence between the superposition principle for
solutions related by the Backlund transformation, and the method of solving a
Riccati map by exploiting two kn own particular solutions. This leads to an
expression for the N-soliton-type solutions of a generic equation within this
class. As a particular instance we give an explicit N-soliton solution for the
primary model, which is Adler's lattice equation (or Q4).Comment: 22 page
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