Search for Magnetic Field Induced Gap in a High-Tc Superconductor

Break junctions made of the optimally doped high temperature superconductor Bi2Sr2Ca2CuO8 with Tc of 90 K has been investigated in magnetic fields up to 12 T, at temperatures from 4.2 K to Tc. The junction resistance varied between 1kOhm and 300kOhm. The differential conductance at low biases did not exhibit a significant magnetic field dependence, indicating that a magnetic-field-induced gap (Krishana et al., Science 277 83 (1997)), if exists, must be smaller than 0.25 meV.Comment: 3 pages, 2 figure

Co-combustion of sewage sludge with wood/coal in a circulating fluidised bed boiler - A study of NO and N2O emissions

Reduction of emissions of NO and N2O from co-combustion of wet or dried sewage sludge with coal or wood is investigated. This is motivated by the high nitrogen content in sewage sludge that may give rise to high emissions. An advanced air-staging method for combustion in circulating fluidised bed is applied. It is shown that with fluidised bed combustion the emissions are low as long as the sludge fraction is not too high (say, less than 25%), and the conversion of fuel nitrogen to NO or N2O is only a few percent. However, air staging as such is not efficient for high volatile fuels, and any air supply method can be applied in such a case, in contrast to combustion of coal, when the air supply arrangement has a decisive influence

Strong-Coupling Features Due to Quasiparticle Interaction in Two Dimensional Superconductors

I calculate the effect of interactions among superconducting quasiparticles in two-dimensional(2D) a superconductor at T=0. The strength of the effective interaction among the quasiparticles is essentially given by the screened Coulomb interaction which has strength at low frequency because of the gapless nature of the plasmon. This is in contrast to three dimensions where the effective interaction has negligible weight at frequencies $\sim \Delta$, the superconducting gap. The quasiparticle interactions give rise to strong-coupling effects in experimental quantities which are beyond the conventional Eliashberg treatment of superconductivity. The present calculation offers an explanation of why these effects are much larger in 2D than in 3D superconductors and, in particular, why the analogous strong-coupling effects due to quasiparticle interactions are seen in data on the quasi-2D cuprate superconductors. the strong-coupling features seen in data on the cuprates are discussed in light of the present calculation.Comment: 18 pages including 11 figures Revte

Impact of changing US cigarette smoking patterns on incident cancer: Risks of 20 smoking-related cancers among the women and men of the NIH-AARP cohort

Background: Historically, US women started smoking at a later age than men and had lower relative risks for smoking-related cancers. However, more recent birth cohorts of women and men have similar smoking histories and have now reached the high-risk age for cancer. The impact of these changes on cancer incidence has not been systematically examined. Methods: Relative risks (RR), 95% confidence intervals (CI) and attributable fractions were calculated for cigarette smoking and incidence of 20 smoking-related cancers in 186 057 women and 266 074 men of the National Institutes of Health-AARP cohort, aged 50 to 71 years in 1995 and followed for 11 years. Results: In the cohort, which included participants born between 1924 and 1945, most women and men started smoking as teenagers. RRs for current vs never smoking were similar in women and men for the following cancers: lung squamous-cell (RR women: 121.4, 95% CI: 57.3–257.4; RR men:114.6, 95% CI: 61.2–214.4), lung adenocarcinoma (RR women: 11.7, 95% CI: 9.8–14.0; RR men: 15.6, 95% CI: 12.5–19.6), laryngeal (RR women: 37.0, 95% CI: 14.9–92.3; RR men: 13.8, 95% CI: 9.3–20.2), oral cavity-pharyngeal (RR women:4.4, 95% CI: 3.3–6.0; RR men: 3.8, 95% CI: 3.0–4.7), oesophageal squamous cell (RR women: 7.3, 95% CI: 3.5–15.5; RR men: 6.2, 95% CI: 2.8–13.7), bladder (RR women: 4.7, 95% CI: 3.7–5.8; RR men: 4.0, 95% CI: 3.5–4.5), colon (RR women: 1.3, 95% CI: 1.2–1.5; RR men: 1.3, 95% CI: 1.1–1.4), and at other sites, with similar attributable fractions. Conclusions: RRs for current smoking and incidence of many smoking-related cancers are now similar in US women and men, likely reflecting converging smoking patterns

The Role of FGF Signaling in Retinal Development

The development of the retina is a precise balance between intrinsic competence and extrinsic factors. This interplay is known to regulate the generation of cell types in the developing retina and similar mechanisms have been found in other regions of the CNS. In the developing retina, FGFs are a large family of secreted polypeptide growth factors. Fgf15 is the major Fgf expressed during retinal development in mice. Fgf15 is an example of an FGF that has been shown to control proliferation, cell fate specification, differentiation and migration during development. In this thesis I used analysis of specific genes throughout retinal development, as well as characterization of Fgf receptor mutant mice and Fgf15 knockout explant retina. The preliminary data presented evidence that Fgf15 is a good candidate for an extrinsic factor that may regulate retinal progenitor cell proliferation in the developing retina. When combined with the expression data, these findings suggest that in the absence of Fgf signaling, retinal progenitor cells fail to complete their normal developmental program

Co-firing of biomass and other wastes in fluidised bed systems

A project on co-firing in large-scale power plants burning coal is currently funded by the European Commission. It is called COPOWER. The project involves 10 organisations from 6 countries. The project involves combustion studies over the full spectrum of equipment size, ranging from small laboratory-scale reactors and pilot plants, to investigate fundamentals and operating parameters, to proving trials on a commercial power plant in Duisburg. The power plant uses a circulating fluidized bed boiler. The results to be obtained are to be compared as function of scale-up. There are two different coals, 3 types of biomass and 2 kinds of waste materials are to be used for blending with coal for co-firing tests. The baseline values are obtained during a campaign of one month at the power station and the results are used for comparison with those to be obtained in other units of various sizes. Future tests will be implemented with the objective to achieve improvement on baseline values. The fuels to be used are already characterized. There are ongoing studies to determine reactivities of fuels and chars produced from the fuels. Reactivities are determined not only for individual fuels but also for blends to be used. Presently pilot-scale combustion tests are also undertaken to study the effect of blending coal with different types of biomass and waste materials. The potential for synergy to improve combustion is investigated. Early results will be reported in the Conference. Simultaneously, studies to verify the availability of biomass and waste materials in Portugal, Turkey and Italy have been undertaken. Techno-economic barriers for the future use of biomass and other waste materials are identified. The potential of using these materials in coal fired power stations has been assessed. The conclusions will also be reported

Risk Prediction for Breast, Endometrial, and Ovarian Cancer in White Women Aged 50 y or Older: Derivation and Validation from Population-Based Cohort Studies

Background: Breast, endometrial, and ovarian cancers share some hormonal and epidemiologic risk factors. While several models predict absolute risk of breast cancer, there are few models for ovarian cancer in the general population, and none for endometrial cancer. Methods and Findings: Using data on white, non-Hispanic women aged 50+ y from two large population-based cohorts (the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial [PLCO] and the National Institutes of Health–AARP Diet and Health Study [NIH-AARP]), we estimated relative and attributable risks and combined them with age-specific US-population incidence and competing mortality rates. All models included parity. The breast cancer model additionally included estrogen and progestin menopausal hormone therapy (MHT) use, other MHT use, age at first live birth, menopausal status, age at menopause, family history of breast or ovarian cancer, benign breast disease/biopsies, alcohol consumption, and body mass index (BMI); the endometrial model included menopausal status, age at menopause, BMI, smoking, oral contraceptive use, MHT use, and an interaction term between BMI and MHT use; the ovarian model included oral contraceptive use, MHT use, and family history or breast or ovarian cancer. In independent validation data (Nurses' Health Study cohort) the breast and ovarian cancer models were well calibrated; expected to observed cancer ratios were 1.00 (95% confidence interval [CI]: 0.96–1.04) for breast cancer and 1.08 (95% CI: 0.97–1.19) for ovarian cancer. The number of endometrial cancers was significantly overestimated, expected/observed = 1.20 (95% CI: 1.11–1.29). The areas under the receiver operating characteristic curves (AUCs; discriminatory power) were 0.58 (95% CI: 0.57–0.59), 0.59 (95% CI: 0.56–0.63), and 0.68 (95% CI: 0.66–0.70) for the breast, ovarian, and endometrial models, respectively. Conclusions: These models predict absolute risks for breast, endometrial, and ovarian cancers from easily obtainable risk factors and may assist in clinical decision-making. Limitations are the modest discriminatory ability of the breast and ovarian models and that these models may not generalize to women of other races. Please see later in the article for the Editors' Summar