5,461 research outputs found

    Theory and observations of ice particle evolution in cirrus using Doppler radar: evidence for aggregation

    Get PDF
    Vertically pointing Doppler radar has been used to study the evolution of ice particles as they sediment through a cirrus cloud. The measured Doppler fall speeds, together with radar-derived estimates for the altitude of cloud top, are used to estimate a characteristic fall time tc for the `average' ice particle. The change in radar reflectivity Z is studied as a function of tc, and is found to increase exponentially with fall time. We use the idea of dynamically scaling particle size distributions to show that this behaviour implies exponential growth of the average particle size, and argue that this exponential growth is a signature of ice crystal aggregation.Comment: accepted to Geophysical Research Letter

    Relativistic Magnetic Monopole Flux Constraints from RICE

    Get PDF
    We report an upper limit on the flux of relativistic monopoles based on the non-observation of in-ice showers by the Radio Ice Cherenkov Experiment (RICE) at the South Pole. We obtain a 95% C.L. limit of order 10^{-18}/(cm^2-s-sr) for intermediate mass monopoles of 10^7<gamma<10^{12} at the anticipated energy E=10^{16} GeV. This bound is over an order of magnitude stronger than all previously published experimental limits for this range of boost parameters gamma, and exceeds two orders of magnitude improvement over most of the range. We review the physics of radio detection, describe a Monte Carlo simulation including continuous and stochastic energy losses, and compare to previous experimental limits.Comment: 16 pages, 6 figures. Accepted for publication in Phys. Rev. D. Minor revisions, including expanded discussion of monopole energy uncertaint

    Rise and Fall of a Multi-sheet Intrusive Complex, Elba Island, Italy

    Get PDF
    Elba Island intrusive complex: multisheet laccoliths, sheeted pluton, mafic dyke swarm. Laccolith magma fed from dykes and emplaced in crustal discontinuities (traps). Pluton growth by downward stacking of three magma pulses. Laccoliths and plutons: different outcomes of similar processes in different conditions. Emplacement of excess magma in a short time led to massive gravity slide

    Prevalence and Risk Factors for Urinary Incontinence in Overweight and Obese Diabetic Women: Action for Health in Diabetes (Look AHEAD) study

    Get PDF
    OBJECTIVE To determine the prevalence and risk factors for urinary incontinence among different racial/ethnic groups of overweight and obese women with type 2 diabetes. RESEARCH DESIGN AND METHODS Cross-sectional analysis of baseline data from the Action for Health in Diabetes (Look AHEAD) study, a randomized clinical trial with 2,994 overweight/obese women with type 2 diabetes. RESULTS Weekly incontinence (27%) was reported more often than other diabetes-associated complications, including retinopathy (7.5%), microalbuminuria (2.2%), and neuropathy (1.5%). The prevalence of weekly incontinence was highest among non-Hispanic whites (32%) and lowest among African Americans (18%), and Asians (12%) (P \u3c 0.001). Asian and African American women had lower odds of weekly incontinence compared with non-Hispanic whites (75 and 55% lower, respectively; P \u3c 0.001). Women with a BMI of ≥35 kg/m2 had a higher odds of overall and stress incontinence (55–85% higher; P \u3c 0.03) compared with that for nonobese women. Risk factors for overall incontinence, as well as for stress and urgency incontinence, included prior hysterectomy (40–80% increased risk; P \u3c 0.01) and urinary tract infection in the prior year (55–90% increased risk; P \u3c 0.001). CONCLUSIONS Among overweight and obese women with type 2 diabetes, urinary incontinence is highly prevalent and far exceeds the prevalence of other diabetes complications. Racial/ethnic differences in incontinence prevalence are similar to those in women without diabetes, affecting non-Hispanic whites more than Asians and African Americans. Increasing obesity (BMI ≥35 kg/m2) was the strongest modifiable risk factor for overall incontinence and stress incontinence in this diverse cohort

    Thermoneutrality alters gastrointestinal antigen passage patterning and predisposes to oral antigen sensitization in mice

    Get PDF
    Food allergy is an emerging epidemic, and the underlying mechanisms are not well defined partly due to the lack of robust adjuvant free experimental models of dietary antigen sensitization. As housing mice at thermoneutrality (Tn) - the temperature of metabolic homeostasis (26-30°C) - has been shown to improve modeling various human diseases involved in inflammation, we tested the impact of Tn housing on an experimental model of food sensitization. Here we demonstrate that WT BALB/c mice housed under standard temperature (18-20°C, Ts) conditions translocated the luminal antigens in the small intestine (SI) across the epitheliu

    Epistemic and social scripts in computer-supported collaborative learning

    Get PDF
    Collaborative learning in computer-supported learning environments typically means that learners work on tasks together, discussing their individual perspectives via text-based media or videoconferencing, and consequently acquire knowledge. Collaborative learning, however, is often sub-optimal with respect to how learners work on the concepts that are supposed to be learned and how learners interact with each other. One possibility to improve collaborative learning environments is to conceptualize epistemic scripts, which specify how learners work on a given task, and social scripts, which structure how learners interact with each other. In this contribution, two studies will be reported that investigated the effects of epistemic and social scripts in a text-based computer-supported learning environment and in a videoconferencing learning environment in order to foster the individual acquisition of knowledge. In each study the factors ‘epistemic script’ and ‘social script’ have been independently varied in a 2×2-factorial design. 182 university students of Educational Science participated in these two studies. Results of both studies show that social scripts can be substantially beneficial with respect to the individual acquisition of knowledge, whereas epistemic scripts apparently do not to lead to the expected effects

    A cross-sectional analysis of factors associated with detection of oncogenic human papillomavirus in human immunodeficiency virus-infected and uninfected Kenyan women

    Get PDF
    BACKGROUND: Cervical cancer is caused by oncogenic human papillomaviruses (HPV) and is one of the most common malignancies in women living in sub-Saharan Africa. Women infected with the human immunodeficiency virus (HIV) have a higher incidence of cervical cancer, but the full impact on HPV detection is not well understood, and associations of biological and behavioral factors with oncogenic HPV detection have not been fully examined. Therefore, a study was initiated to investigate factors that are associated with oncogenic HPV detection in Kenyan women. METHODS: Women without cervical dysplasia were enrolled in a longitudinal study. Data from enrollment are presented as a cross-sectional analysis. Demographic and behavioral data was collected, and HPV typing was performed on cervical swabs. HIV-uninfected women (n = 105) and HIV-infected women (n = 115) were compared for demographic and behavioral characteristics using t-tests, Chi-square tests, Wilcoxon sum rank tests or Fisher\u27s exact tests, and for HPV detection using logistic regression or negative binomial models adjusted for demographic and behavioral characteristics using SAS 9.4 software. RESULTS: Compared to HIV-uninfected women, HIV-infected women were older, had more lifetime sexual partners, were less likely to be married, were more likely to regularly use condoms, and were more likely to have detection of HPV 16, other oncogenic HPV types, and multiple oncogenic types. In addition to HIV, more lifetime sexual partners was associated with a higher number of oncogenic HPV types (aIRR 1.007, 95% CI 1.007-1.012). Greater travel distance to the clinic was associated with increased HPV detection (aOR for detection of \u3e /= 2 HPV types: 3.212, 95% CI 1.206-8.552). Older age (aOR for HPV 16 detection: 0.871, 95% CI 0.764-0.993) and more lifetime pregnancies (aOR for detection of oncogenic HPV types: 0.706, 95% CI, 0.565-0.883) were associated with reduced detection. CONCLUSION: HIV infection, more lifetime sexual partners, and greater distance to health-care were associated with a higher risk of oncogenic HPV detection, in spite of ART use in those who were HIV-infected. Counseling of women about sexual practices, improved access to health-care facilities, and vaccination against HPV are all potentially important in reducing oncogenic HPV infections
    corecore