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K Hicks

Publications and source records attributed to K Hicks.

At least 19 recordsLinked to original sources
PubMed2003

Beam-polarization asymmetries for the p(gamma-->, K+)Lambda and p(gamma-->, K+)Sigma(0) reactions for E(gamma)=1.5-2.4 GeV.

Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6<cos((theta(c.m.)(K+))<1.0 by using linearly polarized photons at the Laser-Electron-Photon facility at SPring-8 (LEPS). The observed asymmetries are positive and gradually increase with rising photon energy. The data are not consistent with theoretical predictions based on tree-level effective-Lagrangian approaches. Including the new results in the development of the models is, therefore, crucial for understanding the reaction mechanism and to test the presence of baryon resonances which are predicted in quark models but are thus far undiscovered.

Journal Article↗
PubMed2003

Measurement of ep-->e' ppi+ pi- and baryon resonance analysis.

The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in the resonance region for 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

Journal Article↗
PubMed2003

Evidence for a narrow S = +1 baryon resonance in photoproduction from the neutron.

The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54+/-0.01 GeV/c(2) with a width smaller than 25 MeV/c(2) and a Gaussian significance of 4.6sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uuddsmacr;) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.

Journal Article↗
PubMed2003

First measurement of transferred polarization in the exclusive ep-->e'K+Lambda--> reaction.

The first measurements of the transferred polarization for the exclusive e-->p-->e(')K+Lambda--> reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q2 from 0.3 to 1.5 (GeV/c)(2), W from 1.6 to 2.15 GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the ssmacr; quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.

Journal Article↗
PubMed2003

Photoproduction of the omega meson on the proton at large momentum transfer.

The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6<W<2.9 GeV) was measured up to a momentum transfer -t=5 GeV2 using the CLAS detector at Jefferson Laboratory. The omega channel was identified by detecting a proton and pi(+) in the final state and using the missing mass technique. While the low momentum transfer region shows the typical diffractive pattern expected from Pomeron and Reggeon exchange, at large -t the differential cross section has a flat behavior. This feature can be explained by introducing quark interchange processes in addition to the QCD-inspired two-gluon exchange.

Journal Article↗
PubMed2002

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV.

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Journal Article↗
PubMed2002

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition.

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

Journal Article↗
PubMed2002

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region.

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Journal Article↗
PubMed2002

Treatment of diffuse alveolar hemorrhage after allogeneic bone marrow transplant with recombinant factor VIIa.

Diffuse alveolar hemorrhage (DAH) is a potentially life-threatening pulmonary toxicity that occurs in 1-21% of patients following bone marrow transplantation. The syndrome is associated with a high mortality rate; and current treatment options are limited. Recombinant factor VIIa (rFVIIa, Novoseven) has recently been approved for the treatment of bleeding in patients with hemophilia A/B with inhibitors. A greater understanding of the mechanism by which rFVIIa restores hemostasis has recently become available; with in vitro evidence supporting that the thrombin burst achieved by rFVIIa is independent of the presence or binding to tissue factor. This insight has suggested a range of other potential clinical uses for the drug; including the setting of pulmonary hemorrhage. We review our experience with using rFVIIa for treatment of DAH in a patient with acute myelogenous leukemia following a matched unrelated donor bone marrow transplant. Boluses of 90 microg/kg rFVIIa were given every 3 h x 4 doses/day, concurrently with high-dose corticosteroids and maintenance of a platelet count >50 000/mm(3). Rapid clinical and radiological improvement was noted within several doses of rFVIIa, with discontinuation of the drug after eight doses. However, the patient's clinical condition began to rapidly deteriorate following cessation of rVIIa, resulting in reinstitution of therapy 24 h later. The patient again exhibited rapid clinical improvement; and rFVIIa was continued for an additional 16 doses with no further evidence of pulmonary hemorrhage noted. No toxicity or adverse events were observed with rFVIIa treatment. Our experience indicates that rFVIIa may be an effective treatment option for DAH post bone marrow transplant; although further clinical studies are needed before recommendations can be made regarding off label use of rFVIIa in this clinical setting.

Adult↗
PubMed2001

Diminished frequency of interleukin-10-secreting, T-cell receptor peptide-reactive T cells in multiple sclerosis patients might allow expansion of activated memory T cells bearing the cognate BV gene.

T cells responsive to T-cell receptor (TCR) determinants may regulate pathogenic Th1 responses in patients with multiple sclerosis (MS) through interleukin (IL)-10-dependent bystander suppression. In this study, innate IL-10- and interferon (IFN)-gamma-secreting T cells responsive to TCR peptides were quantified in peripheral blood mononuclear cells of MS patients and healthy controls (HC) using the ELISPOT assay. Most HC had vigorous IL-10 but low IFN-gamma frequencies to BV5S2 and BV6S1 peptides. In contrast, MS patients had significantly lower IL-10 frequency responses to the TCR peptides but normal responses to concanavalin A. Patients undergoing TCR-peptide vaccination had moderate responses that fluctuated in concert with vaccination. In an MS patient and HC, expression of BV6S1 by activated memory T cells was inversely associated with the presence of IL-10-secreting BV6S1-reactive T cells. These results suggest that MS patients have diminished frequencies of innate TCR-reactive T cells that may allow oligoclonal expansion of activated autoreactive Th1 effector cells expressing cognate V genes.

Adult↗
PubMed2001

Photoproduction of the rho(0) meson on the proton at large momentum transfer.

The differential cross section, d sigma/dt, for rho(0) meson photoproduction on the proton above the resonance region was measured up to a momentum transfer -t = 5 GeV2 using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The rho(0) channel was extracted from the measured two charged-pion cross sections by fitting the pi(+)pi(-) and p pi(+) invariant masses. The low momentum transfer region shows the typical diffractive pattern expected from Reggeon exchange. The flatter behavior at large -t cannot be explained solely in terms of QCD-inspired two-gluon exchange models. The data indicate that other processes, like quark interchange, are important to fully describe rho photoproduction.

Journal Article↗
PubMed2001

The ep -->e'p eta reaction at and above the S11(1535) baryon resonance.

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Journal Article↗
PubMed2001

Correlates of participation in a family-directed tobacco and alcohol prevention program for adolescents.

This study examined correlates of program initiation and completion in a family-directed program that involved families of adolescents throughout the United States. Correlates varied by whether program initiation, program completion, or the number of activities completed was the indicator of participation. In final regression models, participation was relatively likely by non-Hispanic whites when compared with persons of race/ethnicity other than white, black, and Hispanic; by families with a female adolescent as the program recipient; by families with mothers who had many years of education; and by families with both parents living in the household. There was more participation if parents thought their child would smoke in the future and if the parent thought the adolescent did not smoke currently. Participation was higher if the adolescent felt strongly attached to the parent and if parents did not smoke. The findings are considered in the context of similar programs and future research on family-directed programs to prevent adolescent tobacco and alcohol use.

Adolescent↗
PubMed2001

Acidification in developing countries: ecosystem sensitivity and the critical load approach on a global scale.

Acidification represents a growing threat to certain developing country ecosystems in tropical and subtropical climates. A methodology investigating the extent of acidification risks from sulfur emissions on a global scale is presented. Atmospheric transfer models have been used to calculate transfer and deposition of sulfur (using emissions for 1990 and a projection for 2050) and alkaline soil dust. A method to derive the relative sensitivity of terrestrial ecosystems is explained and preliminary critical load values are assigned. A range of values for critical loads and base cation deposition have been used to investigate uncertainty in maps depicting the excess of deposition above critical loads. These show an increasing risk of acidification in 2050 in extended regions of southern and eastern Asia, as well as parts of southern Africa, in comparison to 1990. Certain areas, especially in Asia, are shown at risk even when high values of critical load and base cation deposition are used.

Acids↗
PubMed2000

Role of tumor necrosis factor-alpha inhibition with inflixiMAB in cancer therapy and hematopoietic stem cell transplantation.

Tumor necrosis factor (TNF)-alpha is a central cytotoxic and proinflammatory cytokine. Research on the benefits of TNF-alpha inhibition as a form of therapy has focused almost exclusively on autoimmune, inflammatory disorders. InflixiMAB, a chimeric antibody to human TNF-alpha, was recently approved for the management of Crohn disease and rheumatoid arthritis. The potential applications of inflixiMAB in the management of cancer are just beginning to be explored. This article reviews the biology, mechanism of action, pharmacology, and toxicity of inflixiMAB. Existing clinical experience and inflixiMAB's potential role as an immunosuppressant and antitumor agent in the management of cancer are also discussed.

Antibodies, Monoclonal↗
PubMed1998

Jejuno-ileal bypass, enteric hyperoxaluria, and oxalate nephrosis: a role for polarised light in the renal biopsy.

Enteric hyperoxaluria, a complication of jejuno-ileal bypass, is associated with renal failure owing to oxalate nephrosis or tubulo-interstitial nephritis. A 54 year old woman developed renal failure 17 months after jejuno-ileal bypass for morbid obesity. Renal biopsy showed widespread acute on chronic damage to the tubulo-interstitial compartment with extensive deposition of oxalate crystals. The extent of oxalate deposition was only evident on polarisation of the biopsy.

Acute Kidney Injury↗