993 research outputs found

    Epitaxial growth of iron iodide films on Fe(l10)

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    The interaction of iodine vapor on an Fe(110) single crystal surface at room temperature has been investigated primarily through the use of LEED and UPS. Both a series of chemisorbed overlayers and an epitaxial iodide layer are observed. Iodide formation proceeds through an island growth mechanism with the iodide basal plane parallel to the Fe(110) surface. Evidence is presented that the defects introduced on the surface during argon ion sputtering may be important as nucleation sites for iodide growth. The results are compared with the results of previous studies

    Epitaxial growth of iron iodide films on Fe(l10)

    Get PDF
    The interaction of iodine vapor on an Fe(110) single crystal surface at room temperature has been investigated primarily through the use of LEED and UPS. Both a series of chemisorbed overlayers and an epitaxial iodide layer are observed. Iodide formation proceeds through an island growth mechanism with the iodide basal plane parallel to the Fe(110) surface. Evidence is presented that the defects introduced on the surface during argon ion sputtering may be important as nucleation sites for iodide growth. The results are compared with the results of previous studies

    Hospitalization and Mortality Outcomes among Childhood Cancer Survivors by Race, Ethnicity, and Time since Diagnosis

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    Importance: Cancer outcomes are relatively poor in adults who belong to minoritized racial and ethnic groups. Survival and long-term outcomes by race and ethnicity in individuals with childhood cancers are less studied. Objective: To evaluate survival and hospitalization among American Indian and Alaska Native, Asian, Black, and Hispanic children compared with non-Hispanic White children with cancer. Design, Setting, and Participants: This cohort study evaluated all individuals born in Washington State who were younger than 20 years (hereafter referred to as children) and had been diagnosed with cancer during 1987 to 2012, with follow-up ranging from 1 to 27 years. The data subset was built in 2019, and statistical analyses were completed in January 2022. Exposures: Race and ethnicity. Main Outcomes and Measures: Mortality and hospitalization events for all other racial and ethnic groups relative to non-Hispanic White children estimated by Cox proportional hazards regressions for the first 5 years after diagnosis and among cancer survivors 5 or more years after diagnosis. Results: A total of 4222 children (mean [SD] age, 8.4 [6.4] years; 2199 [52.1%] male; 113 American Indian and Alaska Native [2.7%], 311 Asian [7.4%], 196 Black [4.6%], 387 Hispanic [9.2%], and 3215 non-Hispanic White [76.1%]) with cancer diagnosed at younger than 20 years during 1987 to 2012 were included. Mortality was similar across all groups. Compared with non-Hispanic White survivors at less than 5 years after diagnosis, there were no greatly increased hazard ratios (HRs) for hospitalization. Among survivors at 5 or more years after diagnosis, hospitalization HRs were 1.7 (95% CI, 1.0-3.0) for American Indian and Alaska Native survivors and 1.5 (95% CI, 0.9-2.4) for Black survivors. Significantly increased HRs among Hispanic children were observed for infection-related (HR, 1.4; 95% CI, 1.2-1.6), endocrine-related (HR, 1.3; 95% CI, 1.1-1.6), hematologic-related (HR, 1.3; 95% CI, 1.1-1.5), respiratory-related (HR, 1.3; 95% CI, 1.0-1.5), and digestive-related (HR, 1.2; 95% CI, 1.0-1.5) conditions. American Indian and Alaskan Native children had increased HRs for infection-related (HR, 2.3; 95% CI, 1.2-4.5), hematologic-related (HR, 3.0; 95% CI, 1.4-6.5), and digestive-related (HR, 2.6; 95% CI, 1.3-5.4) conditions. Both American Indian and Alaska Native (HR, 3.6; 95% CI, 1.4-9.0) and Black (HR, 2.5; 95% CI, 1.2-5.5) children had increased mental health-related hospitalizations and death. Conclusions and Relevance: In this cohort study, disproportionately increased long-term risks of hospitalization for physical and mental conditions may have contributed to worse outcomes by race. A key component to bridging the morbidity gap by race is improved understanding of reasons for greater cause-specific hospitalizations in some groups, with development of culturally appropriate intervention strategies.

    High Energy QCD: Stringy Picture from Hidden Integrability

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    We discuss the stringy properties of high-energy QCD using its hidden integrability in the Regge limit and on the light-cone. It is shown that multi-colour QCD in the Regge limit belongs to the same universality class as superconformal N\cal{N}=2 SUSY YM with Nf=2NcN_f=2N_c at the strong coupling orbifold point. The analogy with integrable structure governing the low energy sector of N\cal{N}=2 SUSY gauge theories is used to develop the brane picture for the Regge limit. In this picture the scattering process is described by a single M2 brane wrapped around the spectral curve of the integrable spin chain and unifying hadrons and reggeized gluons involved in the process. New quasiclassical quantization conditions for the complex higher integrals of motion are suggested which are consistent with the SS-duality of the multi-reggeon spectrum. The derivation of the anomalous dimensions of the lowest twist operators is formulated in terms of the Riemann surfacesComment: 37 pages, 3 figure

    Strings in Homogeneous Background Spacetimes

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    The string equations of motion for some homogeneous (Kantowski-Sachs, Bianchi I and Bianchi IX) background spacetimes are given, and solved explicitly in some simple cases. This is motivated by the recent developments in string cosmology, where it has been shown that, under certain circumstances, such spacetimes appear as string-vacua. Both tensile and null strings are considered. Generally, it is much simpler to solve for the null strings since then we deal with the null geodesic equations of General Relativity plus some additional constraints. We consider in detail an ansatz corresponding to circular strings, and we discuss the possibility of using an elliptic-shape string ansatz in the case of homogeneous (but anisotropic) backgrounds.Comment: 25 pages, REVTE

    Neutrino-Deuteron Scattering in Effective Field Theory at Next-to-Next-to Leading Order

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    We study the four channels associated with neutrino-deuteron breakup reactions at next-to-next to leading order in effective field theory. We find that the total cross-section is indeed converging for neutrino energies up to 20 MeV, and thus our calculations can provide constraints on theoretical uncertainties for the Sudbury Neutrino Observatory. We stress the importance of a direct experimental measurement to high precision in at least one channel, in order to fix an axial two-body counterterm.Comment: 32 pages, 14 figures (eps

    Specific Heat of Liquid Helium in Zero Gravity very near the Lambda Point

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    We report the details and revised analysis of an experiment to measure the specific heat of helium with subnanokelvin temperature resolution near the lambda point. The measurements were made at the vapor pressure spanning the region from 22 mK below the superfluid transition to 4 uK above. The experiment was performed in earth orbit to reduce the rounding of the transition caused by gravitationally induced pressure gradients on earth. Specific heat measurements were made deep in the asymptotic region to within 2 nK of the transition. No evidence of rounding was found to this resolution. The optimum value of the critical exponent describing the specific heat singularity was found to be a = -0.0127+ - 0.0003. This is bracketed by two recent estimates based on renormalization group techniques, but is slightly outside the range of the error of the most recent result. The ratio of the coefficients of the leading order singularity on the two sides of the transition is A+/A- =1.053+ - 0.002, which agrees well with a recent estimate. By combining the specific heat and superfluid density exponents a test of the Josephson scaling relation can be made. Excellent agreement is found based on high precision measurements of the superfluid density made elsewhere. These results represent the most precise tests of theoretical predictions for critical phenomena to date.Comment: 27 Pages, 20 Figure

    Measurement of the neutron magnetic form factor from inclusive quasielastic scattering of polarized electrons from polarized 3He

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    We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3He target. The neutron magnetic form factor GMn has been extracted from the measured asymmetry based on recent PWIA calculations using spin-dependent spectral functions. Our determination of GMn at Q2=0.19 (GeV/c)2 agrees with the dipole parametrization. This experiment represents the first measurement of the neutron magnetic form factor using spin-dependent electron scattering

    Genuine Correlations of Like-Sign Particles in Hadronic Z0 Decays

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    Correlations among hadrons with the same electric charge produced in Z0 decays are studied using the high statistics data collected from 1991 through 1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth order are used to measure genuine particle correlations as a function of the size of phase space domains in rapidity, azimuthal angle and transverse momentum. Both all-charge and like-sign particle combinations show strong positive genuine correlations. One-dimensional cumulants initially increase rapidly with decreasing size of the phase space cells but saturate quickly. In contrast, cumulants in two- and three-dimensional domains continue to increase. The strong rise of the cumulants for all-charge multiplets is increasingly driven by that of like-sign multiplets. This points to the likely influence of Bose-Einstein correlations. Some of the recently proposed algorithms to simulate Bose-Einstein effects, implemented in the Monte Carlo model PYTHIA, are found to reproduce reasonably well the measured second- and higher-order correlations between particles with the same charge as well as those in all-charge particle multiplets.Comment: 26 pages, 6 figures, Submitted to Phys. Lett.
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