Weak Localization Effect in Superconductors by Radiation Damage

Large reductions of the superconducting transition temperature $T_{c}$ and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and Ternary superconductors, and $\rm{NbSe_{2}}$ in the high fluence regime. We examine these behaviors based on the recent theory of weak localization effect in superconductors. We find a good fitting to the experimental data. In particular, weak localization correction to the phonon-mediated interaction is derived from the density correlation function. It is shown that weak localization has a strong influence on both the phonon-mediated interaction and the electron-phonon interaction, which leads to the universal correlation of $T_{c}$ and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information, Plesse see http://www.fen.bilkent.edu.tr/~yjki

Degradation and healing in a generalized neo-Hookean solid due to infusion of a fluid

The mechanical response and load bearing capacity of high performance polymer composites changes due to diffusion of a fluid, temperature, oxidation or the extent of the deformation. Hence, there is a need to study the response of bodies under such degradation mechanisms. In this paper, we study the effect of degradation and healing due to the diffusion of a fluid on the response of a solid which prior to the diffusion can be described by the generalized neo-Hookean model. We show that a generalized neo-Hookean solid - which behaves like an elastic body (i.e., it does not produce entropy) within a purely mechanical context - creeps and stress relaxes when infused with a fluid and behaves like a body whose material properties are time dependent. We specifically investigate the torsion of a generalized neo-Hookean circular cylindrical annulus infused with a fluid. The equations of equilibrium for a generalized neo-Hookean solid are solved together with the convection-diffusion equation for the fluid concentration. Different boundary conditions for the fluid concentration are also considered. We also solve the problem for the case when the diffusivity of the fluid depends on the deformation of the generalized neo-Hookean solid.Comment: 24 pages, 10 figures, submitted to Mechanics of Time-dependent Material

IMI-Management and Investigation of High Myopia in Infants and Young Children

The purpose of this study was to evaluate the epidemiology, etiology, clinical assessment, investigation, management, and visual consequences of high myopia (≤−6 diopters [D]) in infants and young children

Neutron production in semiprototypic target assemblies for accelerator transmutation technology

Integral neutron production was measured by the manganese-activation technique, on targets semiprototypic of spallation-neutron-driven transmutation systems, after irradiation by 400-MeV to 2.0-GeV protons. The purpose of these experiments was to provide data to benchmark nuclear transport codes for targets irradiated by protons in this energy range, as well as to evaluate design options to maximize the production of spallation neutrons in various targets under consideration. These computer codes are used to design accelerator systems that will utilize spallation neutrons for the generation of tritium, transmutation of nuclear waste, production of radioisotopes, and other scientific investigations. Some of the targets used in this investigation were semiprototypic of the proposed Accelerator Production of Tritium target. Other targets were included to provide data to test the computational models in the codes. Total neutron production is the main factor that determines the economics of transmutation for a particular accelerator design. Comparisons of the data reported here with calculations from computer simulations show agreement to within 15% over the entire energy region for most of the targets

The influence of structural racism, pandemic stress, and SARS-CoV-2 infection during pregnancy with adverse birth outcomes

BACKGROUND: Structural racism and pandemic-related stress from the COVID-19 pandemic may increase the risk of adverse birth outcomes. OBJECTIVE: Our objective was to examine associations between neighborhood measures of structural racism and pandemic stress with 3 outcomes: SARS-CoV-2 infection, preterm birth, and delivering small-for-gestational-age newborns. Our secondary objective was to investigate the joint association of SARS-CoV-2 infection during pregnancy and neighborhood measures with preterm birth and delivering small-for-gestational-age newborns. STUDY DESIGN: We analyzed data of 967 patients from a prospective cohort of pregnant persons in New York City, comprising 367 White (38%), 169 Black (17%), 293 Latina (30%), and 87 Asian persons (9%), 41 persons of other race or ethnicity (4%), and 10 of unknown race or ethnicity (1%). We evaluated structural racism (social/built structural disadvantage, racial-economic segregation) and pandemic-related stress (community COVID-19 mortality, community unemployment rate increase) in quartiles by zone improvement plan code. SARS-CoV-2 serologic enzyme-linked immunosorbent assay was performed on blood samples from pregnant persons. We obtained data on preterm birth and small-for-gestational-age newborns from an electronic medical record database. We used log-binomial regression with robust standard error for clustering by zone improvement plan code to estimate associations of each neighborhood measure separately with 3 outcomes: SARS-CoV-2 infection, preterm birth, and small-for-gestational-age newborns. Covariates included maternal age, parity, insurance status, and body mass index. Models with preterm birth and small-for-gestational-age newborns as the dependent variables additionally adjusted for SARS-CoV-2 infection. RESULTS: A total of 193 (20%) persons were SARS-CoV-2-seropositive, and the overall risks of preterm birth and small-for-gestational-age newborns were 8.4% and 9.8%, respectively. Among birthing persons in neighborhoods in the highest quartile of structural disadvantage (n=190), 94% were non-White, 50% had public insurance, 41% were obese, 32% were seropositive, 11% delivered preterm, and 12% delivered a small-for-gestational-age infant. Among birthing persons in neighborhoods in the lowest quartile of structural disadvantage (n=360), 39% were non-White, 17% had public insurance, 15% were obese, 9% were seropositive, 6% delivered preterm, and 10% delivered a small-for-gestational-age infant. In adjusted analyses, structural racism measures and community unemployment were associated with both SARS-CoV-2 infection and preterm birth, but not small-for-gestational-age infants. High vs low structural disadvantage was associated with an adjusted relative risk of 2.6 for infection (95% confidence interval, 1.7-3.9) and 1.7 for preterm birth (95% confidence interval, 1.0-2.9); high vs low racial-economic segregation was associated with adjusted relative risk of 1.9 (95% confidence interval, 1.3-2.8) for infection and 2.0 (95% confidence interval, 1.3-3.2) for preterm birth; high vs low community unemployment increase was associated with adjusted relative risk of 1.7 (95% confidence interval, 1.2-1.5) for infection and 1.6 (95% confidence interval, 1.0-2.8) for preterm birth. COVID-19 mortality rate was associated with SARS-CoV-2 infection but not preterm birth or small-for-gestational-age infants. SARS-CoV-2 infection was not independently associated with birth outcomes. We found no interaction between SARS-CoV-2 infection and neighborhood measures on preterm birth or small-for-gestational-age infants. CONCLUSION: Neighborhood measures of structural racism were associated with both SARS-CoV-2 infection and preterm birth, but these associations were independent and did not have a synergistic effect. Community unemployment rate increases were also associated with an increased risk of preterm birth independently of SARS-CoV-2 infection. Mitigating these factors might reduce the impact of the pandemic on pregnant people