546 research outputs found

    On the accretion disc properties in eclipsing dwarf nova EM Cyg

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    In this paper we analyzed the behavior of the unusual dwarf nova EM Cyg using the data obtained in April-October, 2007 in Vyhorlat observatory (Slovak Republic) and in September, 2006 in Crimean Astrophysical Observatory (Ukraine). During our observations EM Cyg has shown outbursts in every 15-40 days. Because on the light curves of EM Cyg the partial eclipse of an accretion disc is observed we applied the eclipse mapping technique to reconstruct the temperature distribution in eclipsed parts of the disc. Calculations of the accretion rate in the system were made for the quiescent and the outburst states of activity for different distances.Comment: 6 pages, 3 figures, accepted in Astrophysics and Space Scienc

    Personal identity (de)formation among lifestyle travellers: A double-edged sword?

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    This article explores the personal identity work of lifestyle travellers – individuals for whom extended leisure travel is a preferred lifestyle that they return to repeatedly. Qualitative findings from in-depth semi-structured interviews with lifestyle travellers in northern India and southern Thailand are interpreted in light of theories on identity formation in late modernity that position identity as problematic. It is suggested that extended leisure travel can provide exposure to varied cultural praxes that may contribute to a sense of social saturation. Whilst a minority of the respondents embraced a saturation of personal identity in the subjective formation of a cosmopolitan cultural identity, several of the respondents were paradoxically left with more identity questions than answers as the result of their travels

    The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

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    In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method

    Geological controls on the geometry of incised-valley fills: Insights from a global dataset of late-Quaternary examples

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    Incised valleys that develop due to relative sea-level change are common features of continental shelves and coastal plains. Assessment of the factors that control the geometry of incised-valley fills has hitherto largely relied on conceptual, experimental or numerical models, else has been grounded on case studies of individual depositional systems. Here, a database-driven statistical analysis of 151 late-Quaternary incised-valley fills has been performed, the aim being to investigate the geological controls on their geometry. Results of this analysis have been interpreted with consideration of the role of different processes in determining the geometry of incised-valley fills through their effect on the degree and rate of river incision, and on river size and mobility. The studied incised-valley fills developed along active margins are thicker and wider, on average, than those along passive margins, suggesting that tectonic setting exerts a control on the geometry of incised-valley fills, likely through effects on relative sea-level change and river behaviour, and in relation to distinct characteristics of basin physiography, water discharge and modes of sediment delivery. Valley-fill geometry is positively correlated with the associated drainage-basin size, confirming the dominant role of water discharge. Climate is also inferred to exert a potential control on valley-fill dimensions, possibly through modulations of temperature, peak precipitation, vegetation and permafrost, which would in turn affect water discharge, rates of sediment supply and valley-margin stability. Shelves with slope breaks that are currently deeper than 120 m contain incised-valley fills that are thicker and wider, on average, than those hosted on shelves with breaks shallower than 120 m. No correlation exists between valley-fill thickness and present-day coastal-prism convexity, which is measured as the difference in gradient between lower coastal plains and inner shelves. These findings challenge some concepts embedded in sequence stratigraphic thinking, and have significant implications for analysis and improved understanding of source-to-sink sediment route-ways, and for attempting predictions of the occurrence and characteristics of hydrocarbon reservoirs

    E-cigarettes and urologic health: a collaborative review of toxicology, epidemiology, and potential risks

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    Context: Use of electronic cigarettes (ECs) is on the rise in most high-income countries. Smoking conventional cigarettes is a known risk factor for urologic malignancy incidence, progression, and mortality, as well as for other urologic health indicators. The potential impact of EC use on urologic health is therefore of clinical interest to the urology community. Objective: To review the available data on current EC use, including potential benefits in urologic patients, potential issues linked to toxicology of EC constituents, and how this might translate into urologic health risks. Evidence acquisition: A Medline search was carried out in August 2016 for studies reporting urologic health outcomes and EC use. Snowballing techniques were also used to identify relevant studies from recent systematic reviews. A narrative synthesis of data around EC health outcomes, toxicology, and potential use in smoking cessation and health policy was carried out. Evidence synthesis: We found no studies to date that have been specifically designed to prospectively assess urologic health risks, even in an observational setting. Generating such data would be an important contribution to the debate on the role of ECs in public health and clinical practice. There is evidence from a recent Cochrane review of RCTs that ECs can support smoking cessation. There are emerging data indicating that potentially harmful components of ECs such as tobacco-specific nitrosamines, polyaromatic hydrocarbons, and heavy metals could be linked to possible urologic health risks. Conclusions: ECs might be a useful tool to encourage cessation of conventional cigarette smoking. However, data collection around the specific impact of ECs on urologic health is needed to clarify the possible patient benefits, outcomes, and adverse events. Patient summary: While electronic cigarettes might help some people to stop smoking, their overall impact on urologic health is not clear. While electronic cigarettes might help some people to stop smoking, it is not clear if they may be bad for urologic health

    Above- and below-ground biomass accumulation, production, and distribution of sweetgum and loblolly pine grown with irrigation and fertilization.

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    Abstract: Increased forest productivity has been obtained by improving resource availability through water and nutrient amendments. However, more stress-tolerant species that have robust site requirements do not respond consistently to irrigation. An important factor contributing to robust site requirements may be the distribution of biomass belowground, yet available information is limited. We examined the accumulation and distribution of above- and below-ground biomass in sweetgum (Liqrridambar sfyrac$lua L.) and loblolly pine (Pinus taeda L.) stands receiving irrigation and fertilization. Mean annual aboveground production after 4 years ranged from 2.4 to 5.1 ~g.ha-'.year' for sweetgum and from 5.0 to 6.9 ~g.ha-l.year-l for pine. Sweetgum responded positively to irrigation and fertilization with an additive response to irrigation + fertilization. Pine only responded to fertilization. Sweetgum root mass fraction (RME)in creased with fertilization at 2 years and decreased with fertilization at 4 years. There were no detectable treatment differences in loblolly pine RMF. Development explained from 67% to 98% of variation in shoot versus root allometry for ephemeral and perennial tissues, fertilization explained no more than 5% of the variation in for either species, and irrigation did not explain any. We conclude that shifts in allocation from roots to shoots do not explain nutrient-induced growth stimulations

    Regional variations in quality of survival among men with prostate cancer across the United Kingdom

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    Purpose: Prostate cancer incidence, treatment and survival rates vary throughout the United Kingdom (UK) but little is known about regional differences in quality of survival. Objective: To investigate variations in patient-reported outcomes between UK countries and English Cancer Alliances. Design, setting and participants: A cross-sectional postal survey of prostate cancer survivors diagnosed 18-42 months previously. Outcome measurements and statistical analysis: Urinary, bowel, sexual problems and vitality were patient reported using the EPIC-26 questionnaire. General health was also self-assessed. Regional variations were identified using multivariable log-linear regression. Results and limitations: 35,823 men responded; 60.8% of those invited. Self-assessed health was significantly lower than the UK average in Wales and Scotland. Respondents reported more urinary incontinence in Scotland, more urinary irritation/obstruction in Scotland and Northern Ireland (NI), poorer bowel function in Scotland and NI, worse sexual function in Scotland, and reduced vitality/hormonal function in Scotland, Wales and NI. Self-assessed health was poorer than the English average in South Yorkshire and North-East & Cumbria, with more urinary incontinence in North-East & Cumbria and Peninsula, greater sexual problems in West Midlands and poorer vitality in North-East & Cumbria and West Midlands. Limitations include difficulty identifying clinically significant differences and limited information on pre-treatment conditions. Conclusions: Despite adjustment for treatment, clinical and socio-demographic factors, quality of survival among prostate cancer survivors varied by area of residence. Adoption of best practice from areas performing well could support enhanced survival quality in poorer performing areas, particularly with regards bowel problems and vitality, where clinically relevant differences were reported. Patient summary: We conducted a UK-wide survey of patient’s quality of life after treatment for prostate cancer. Outcomes were found to vary depending upon where patients live. Different service providers need to ensure that all prostate cancer patients receive the same follow up care

    Quality of life in men living with advanced and localised prostate cancer: A United Kingdom population-wide patient-reported outcome study of 30,000 men

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    Background. Little is known about the health-related quality of life (HRQL) of men living with advanced prostate cancer. We report population-wide functional outcomes and HRQL in men with all stages of prostate cancer, and identify implications for healthcare delivery. Methods. Men alive 18-42 months after diagnosis of prostate cancer were identified through cancer registration data. A postal survey was administered which contained validated measures to assess a) functional outcomes (EPIC-26 plus use of interventions for sexual dysfunction) and b) generic HRQL (EQ-5D-5L & self-assessed health). Log-linear and binary logistic regression models were used to compare functional outcomes and HRQL across diagnostic stage and self-reported treatment groups. Findings. 35,823 (60.8%) men responded. Stage was known for 85.8%; 19,599 (63.8%) stage I/II, 7,209 (23.4%) stage III, 3,925 (12.8%) stage IV. Functional outcomes: Poor sexual function was common (81.0%), regardless of stage, and over half of men (55.8%) received no intervention for this. Differences in urinary and bowel morbidity were greater with respect to treatment than stage. In men treated with androgen deprivation therapy (ADT), 30.7% reported moderate/big problems with hot flushes, 29.4% with lack of energy and 22.5% with weight gain. HRQL: Overall self-assessed health was similar in men with stage I-III disease, and whilst reduced in those with stage IV cancer, 23.5% with metastatic disease reported no problems on any EQ-5D dimension. Interpretation. Men diagnosed with advanced disease do not report markedly different HRQL outcomes to those diagnosed with localised disease, although substantial problems with hormonal function and fatigue are reported amongst men treated with ADT. Sexual dysfunction is common and the majority of men are not offered helpful intervention or support. Service improvements around sexual rehabilitation and measures to reduce the impact of ADT are required

    How fast can conifers climb mountains? Investigating the effects of a changing climate on the viability of Juniperus seravschanica within the mountains of Oman, and developing a conservation strategy for this tree species

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    The conifer, Juniperus seravschanica is a keystone species within Oman, yet its decline is typical of other arid-adapted, montane tree species. This research aimed to identify causes of decline and subsequent viable conservation strategies; strategies that may have wider application for tree conservation. Decline in J. seravschanica is typified by foliar dieback and little regeneration via seed; traits most apparent at lower altitudes. The research evaluated the viability of seeds collected at three different altitudes: 2100-2220 m (Low), 2300-2400 m (Mid) and 2500-2570 m above sea level (High). In addition, seeds and young trees were planted at these altitudes and maintained under differential irrigation. Results showed that trees grown at Low altitude produced fewer, less-viable seed. Transplanting young trees proved more successful than seed sowing in re-establishing plants in the wild. Age of transplant had an effect, however, with 5-year-old stock showing greater survival ( > 97%) than 2-year-old trees. The younger trees only established well when planted at High altitude, or provided with irrigation at Mid/Low altitudes. Water availability did not entirely explain survival, and in some locations direct heat stress too may be limiting viability. Practical conservation measures include identifying genotypes with greater drought/heat tolerances and planting only more mature nursery trees
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