556 research outputs found

    Implications of the spatial variability of infiltration-water chemistry for the investigation of a karst aquifer: a field study at Milandre test site, Swiss Jura

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    The Milandre test site is an ideal karstic aquifer for studying the spatial heterogeneity of groundwater chemistry. Numerous observation points can be sampled: the spring, the underground river and its tributaries, and boreholes at different depths. The main causes of the spatial variability of the chemical parameters are: nature and localisation of the input, the structure of the infiltration zone, chemical reactions (transit time vs. reaction kinetics) and mixing of different waters. Physico-chemical data on springs discharging from the karstic system represent the sum of this spatial heterogeneity. Therefore, it is difficult to interpret the global-chemical response with a simple mixing model of the aquifer subsystems (runoff, matrix reservoir, epikarst). Chemical constituents related to agricultural inputs show important seasonal variations (coefficient of variation approximately 15%) and parameters linked to rainfall (δ18O) and to the aquifer (Ca2+, HCO3 −) present variations of less than 5%. This result indicates the importance of water storage in the epikarstic aquifer for periods of a few month

    A purely geometric distance to the binary star Atlas, a member of the Pleiades

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    We present radial velocity and new interferometric measurements of the double star Atlas, which permit, with the addition of published interferometric data, to precisely derive the orbital parameters of the binary system and the masses of the components. The derived semi-major axis, compared with its measured angular size, allows to determine a distance to Atlas of 132+-4 pc in a purely geometrical way. Under the assumption that the location of Atlas is representative of the average distance of the cluster, we confirm the distance value generally obtained through main sequence fitting, in contradiction with the early Hipparcos result (118.3+-3.5 pc).Comment: 5 pages, 3 figures, accepted for publication in A&A Letter

    Chronic lymphocytic leukaemia: clinical-aetiological findings in 66 patients and their families

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    <p>Abstract</p> <p>Background</p> <p>Little is known about the aetiology of chronic lymphocytic leukaemia (CLL). The family medical history is a "genomic tool" capturing interactions of genetic susceptibility, shared environment and common behaviours.</p> <p>Methods</p> <p>A cohort of 66 consecutives patients with CLL (probands) was studied in a medical oncology practice (W.W.) from 1981 until 2005. A German version of the NCI medical history questionnaire for cancer aetiology was used. Familial clustering analysis was done by comparing the proportion of specific tumours in the first degree relatives of the CLL practice cohort with corresponding proportions of population-based cancer registry data.</p> <p>Results</p> <p>18 (41%) male and 5 (23%) female CLL probands had multiple malignancies, e.g. 2 meningiomas, 7 and 19 years after diagnosis of CLL. 46 (12%) first degree relatives had malignancies with an excess of CLL. Other conspicuous familial associations are CLL with malignancies of the upper GI tract (oesophagus, stomach) and of the nervous system.</p> <p>Conclusion</p> <p>1. Chronic lymphocytic leukaemia clusters in some families like any other disease. Predisposition genes should be searched. 2. Cancer prevention and early detection should be continued in CLL patients because of their longevity and high risk for multiple malignancies. 3. The overrepresentation of upper GI malignancies in first degree relatives of CLL patients calls for targeted oesophago-gastroscopy screening studies.</p

    Association between reported exposure to road traffic and respiratory symptoms in children: evidence of bias

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    Background Many studies showing effects of traffic-related air pollution on health rely on self-reported exposure, which may be inaccurate. We estimated the association between self-reported exposure to road traffic and respiratory symptoms in preschool children, and investigated whether the effect could have been caused by reporting bias. Methods In a random sample of 8700 preschool children in Leicestershire, UK, exposure to road traffic and respiratory symptoms were assessed by a postal questionnaire (response rate 80%). The association between traffic exposure and respiratory outcomes was assessed using unconditional logistic regression and conditional regression models (matching by postcode). Results Prevalence odds ratios (95% confidence intervals) for self-reported road traffic exposure, comparing the categories ‘moderate' and ‘dense', respectively, with ‘little or no' were for current wheezing: 1.26 (1.13-1.42) and 1.30 (1.09-1.55); chronic rhinitis: 1.18 (1.05-1.31) and 1.31 (1.11-1.56); night cough: 1.17 (1.04-1.32) and 1.36 (1.14-1.62); and bronchodilator use: 1.20 (1.04-1.38) and 1.18 (0.95-1.46). Matched analysis only comparing symptomatic and asymptomatic children living at the same postcode (thus exposed to similar road traffic) showed similar ORs, suggesting that parents of children with respiratory symptoms reported more road traffic than parents of asymptomatic children. Conclusions Our study suggests that reporting bias could explain some or even all the association between reported exposure to road traffic and disease. Over-reporting of exposure by only 10% of parents of symptomatic children would be sufficient to produce the effect sizes shown in this study. Future research should be based only on objective measurements of traffic exposur

    Assessment of Involuntary PFM Contractions in Comparison with Existing Literature and IUGA/ICS Terminology Reports.

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    INTRODUCTION AND HYPOTHESIS Involuntary pelvic floor muscle (PFM) contractions are thought to occur during an increase in intra-abdominal pressure (IAP). Although no studies have assessed their presence in women with normal pelvic floor (PF) function, existing literature links the absence of involuntary PFM contractions to various PF dysfunctions. This study rectifies this lacuna by evaluating involuntary PFM contractions during IAP in healthy nulliparous women with no PF dysfunction, using visual observation and vaginal palpation. Results were compared with the literature and the IUGA/ICS Terminology Reports. METHODS Nulliparous (n=149) women performed three sets of three maximal coughs. Visual observation and vaginal palpation were conducted in the standing and supine positions. The women were not instructed to contract their PFMs. Occurrence rates were calculated for each assessment method and position; differences between positions were analyzed using the Chi-squared test. RESULTS Rates of occurrence of involuntary PFM contraction were low across both assessments and positions (5-17%). Significant differences were found between standing (5%) and supine (15%) positions for visual observation, but not vaginal palpation (15%, 17% respectively). Occurrence rates also differed compared with the literature and terminology reports. CONCLUSIONS Contrary to clinical expectations, rates of occurrence of involuntary PFM contraction among our cohort of nulliparous women were extremely low. Digital palpation results showed high agreement with the terminology reports, but only partial agreement was observed for the visual observation results. Our study underscores the need for more research aimed at defining normal involuntary PF functions, a review of our understanding of involuntary PFM contractions, and better standardized guidelines for involuntary PFM assessment methods

    The Spectrum projection package: improvements in estimating mortality, ART needs, PMTCT impact and uncertainty bounds

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    BACKGROUND: The approach to national and global estimates of HIV/AIDS used by UNAIDS starts with estimates of adult HIV prevalence prepared from surveillance data using either the Estimation and Projection Package (EPP) or the Workbook. Time trends of prevalence are transferred to Spectrum to estimate the consequences of the HIV/AIDS epidemic, including the number of people living with HIV, new infections, AIDS deaths, AIDS orphans, treatment needs and the impact of treatment on survival. METHODS: The UNAIDS Reference Group on Estimates, Modelling and Projections regularly reviews new data and information needs and recommends updates to the methodology and assumptions used in Spectrum. The latest update to Spectrum was used in the 2007 round of global estimates. RESULTS: Several new features have been added to Spectrum in the past two years. The structure of the population was reorganised to track populations by HIV status and treatment status. Mortality estimates were improved by the adoption of new approaches to estimating non-AIDS mortality by single age, and the use of new information on survival with HIV in non-treated cohorts and on the survival of patients on antiretroviral treatment (ART). A more detailed treatment of mother-to-child transmission of HIV now provides more prophylaxis and infant feeding options. New procedures were implemented to estimate the uncertainty around each of the key outputs. CONCLUSIONS: The latest update to the Spectrum program is intended to incorporate the latest research findings and provide new outputs needed by national and international planners

    Variation with mass of \boldmath{B(E3; 0_1^+ \to 3_1^-)} transition rates in A=124−134A=124-134 even-mass xenon nuclei

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    B(E3;01+→31−)B(E3; 0_1^+ \to 3_1^-) transition matrix elements have been measured for even-mass 124−134^{124-134}Xe nuclei using sub-barrier Coulomb excitation in inverse kinematics. The trends in energy E(3−)E(3^-) and B(E3;01+→31−)B(E3; 0_1^+ \to 3_1^-) excitation strengths are well reproduced using phenomenological models based on a strong coupling picture with a soft quadrupole mode and an increasing occupation of the intruder h11/2h_{11/2} orbital.Comment: 5 pages, 4 figures, PRC in pres

    Shell structure underlying the evolution of quadrupole collectivity in S-38 and S-40 probed by transient-field g-factor measurements on fast radioactive beams

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    The shell structure underlying shape changes in neutron-rich nuclei between N=20 and N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in S-38 and S-40 produced as fast radioactive beams. Details of the new methodology are presented. In both S-38 and S-40 there is a fine balance between the proton and neutron contributions to the magnetic moments. Shell model calculations which describe the level schemes and quadrupole properties of these nuclei also give a satisfactory explanation of the g factors. In S-38 the g factor is extremely sensitive to the occupation of the neutron p3/2 orbit above the N=28 shell gap as occupation of this orbit strongly affects the proton configuration. The g factor of deformed S-40 does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.Comment: 10 pages, 36 figures, accepted for publication in Physical Review

    Probing shell structure and shape changes in neutron-rich sulfur isotopes through transient-field g factor measurements on fast radioactive beams of 38S and 40S

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    The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.Comment: 10 pages, 6 figures, accepted in PR
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