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J Ely

Publications and source records attributed to J Ely.

13 recordsLinked to original sources
PubMed2004

Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering.

Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with reanalyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.

Journal Article↗
PubMed2003

Evidence for quark-hadron duality in the proton spin asymmetry A1.

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were scattered off a longitudinally polarized hydrogen target for values of Q2 between 1.2 and 12 GeV2 and values of W2 between 1 and 4 GeV2. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable x. This finding implies that the description of A1 in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of Q2 above 1.6 GeV2.

Journal Article↗
PubMed2003

Q2 dependence of nuclear transparency for exclusive rho0 production.

Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.

Journal Article↗
PubMed2000

A comparison of the classical and modified forms of the continuity equation in the On-X prosthetic heart valve in the aortic position.

BACKGROUND AND AIM OF THE STUDY: The use of echocardiography to determine prosthetic valve hemodynamics has become generally accepted; however, there are still many differing methodologies in use. The continuity equation, which uses the ratio of the subaortic and transaortic velocity-time integrals for determining aortic effective orifice area (EOA), has been established as an accurate method. Another method using the more easily measured peak velocities in ratio has also been employed. These methods were compared to determine if the simpler method gave equivalent results. METHODS: Early postoperative echocardiographic data on prosthetic valves from the MCRI Multicenter Trial were used to compare the two methods of calculating EOA (A2). Results using the two methods were compared by paired t-tests, the Wilcoxon signed rank test, regression and Bland-Altman analysis. RESULTS: Despite a good correlation between the two methods (r = 0.91), results were different when compared by a paired t-test. On average, results by the modified method were 0.2 cm2 lower, but in 28% of cases they were in fact higher than the classical method. CONCLUSION: The modified continuity equation based on the peak velocity ratio does not give the same result as the classical formula based on the velocity-time ratio. The modified method cannot reliably be substituted for the classical method in normally functioning On-X valves.

Adult↗
PubMed1995

The use of unofficial "problem patient" files and interinstitutional information transfer in emergency medicine in Iowa.

The study objectives were to determine the use of "problem patient" files in full-time Emergency Departments (EDs) in the state of Iowa and the frequency of telephone calls made between these departments about drug-seeking patients. The design and setting were a mail survey of 42 EDs in the state of Iowa determined to be staffed full-time by an in-house physician. The participants were the directors of the full time EDs in the state of Iowa. There were no interventions. The measurements and main results are as follows: 38 of 42 sites responded for a response rate of 90%. Of these, 58% keep problem patient lists and consult them an average of 2.6 times per week (range, 0.2 to 7.5). Only 5% have a policy limiting access to the information in these files, and only 14% have any controls over the adding of information. Thirty-seven of the 38 sites reported making and receiving calls to and from other institutions about drug-seeking patients. The mean number of calls made is 23 a year, and the mean number received is 20 per year. Problem patient files are common in EDs in Iowa, as are calls between institutions about drug-seeking patients. These practices compromise patient confidentiality but may be potentially justified in some instances. The lack of controls on access to patient information files and lack of scrutiny of information entered is of concern.

Communication↗
PubMed1992

Comparison of five tandem repeat loci between humans and chimpanzees.

Five tandem repeat loci were studied in humans and chimpanzees using VNTR probes derived from human DNA. Shared alleles were found at three loci and were often the modal allele in one species but never in both. There was no difference in the mean number of alleles per locus. However, these species exhibited substantially different levels of gene diversity, with chimpanzees monomorphic at two loci. Evidence of reduced variability in chimpanzees corroborates earlier comparisons using isozymes and plasma proteins. Molecular mechanisms, population dynamics, or both may be responsible for these differences. Equal numbers of alleles per locus may reflect high mutation rates. By one test, chimpanzees were out of equilibrium at one locus, which may reflect a typing error or population substructure. The long divergence time, and the high probability of backward mutations, precludes accurate estimation of genetic distance between these species.

Alleles↗
PubMed1984

Enhancement of macrophage survival and complement production by factors from cloned T cells.

The addition of supernatants of some cloned mouse T cell lines to guinea pig peritoneal cells in tissue culture increased the production of the second (C2) and fourth (C4) components of complement as well as the enzyme beta-glucuronidase. Enumeration of cell populations demonstrated a simultaneous increase in cell survival. Supernatants that augmented functions of the cultured cells were obtained after alloantigen stimulation of a T cell line of C57BL/6 origin termed L2, but supernatants from a variant cell line derived from L2 and termed L2V had no effect. A delay of as little as 24 h in the addition of L2 T cell factors at the start of the cultures markedly diminished the effects on the cultured cells that were ordinarily observed 1-2 weeks later. These experiments suggest that, in this xenogenic system, complement-enhancing activity is part of a general stimulation of macrophages by cloned T cell factors.

Animals↗
PubMed1983

Biochemical enrichment of lymphokines secreted by a cloned helper T lymphocyte.

The Mls-reactive murine helper T cell clone L2 produces at least 10 lymphokine activities affecting at least five distinct target cells. Culture conditions can be optimized to enable production of high levels of colony-stimulating factors (CSFs) by lectin stimulation of L2 cells under serum-free conditions. Selective enrichment of three lymphokine activities--interleukin 2, CSF, and interferon--can be achieved by using a combination of phenyl-Sepharose and hydroxyapatite chromatography. At least two types of CSF can be separated by concanavalin A-Sepharose chromatography. The CSF that does not bind to concanavalin A-Sepharose can be enriched to a specific activity of at least 5 X 10(8) U/mg of protein by using ion exchange high-pressure liquid chromatography.

Animals↗