2,274 research outputs found

    Analytical model for the perpendicular temperature enhancement in lower-hybrid current drive

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    The enhancement of the perpendicular temperature inside the resonant region, observed in numerical studies of the two-dimensional Fokker-Planck equation, combined with unidirectional RF quasilinear diffusion, is modeled on the basis of the collisional relaxation equations. Strong RF diffusion is assumed and relativistic effects are taken into account. The resulting enhanced perpendicular temperature is a function of the position and the width of the applied RF spectrum. Good agreement with two-dimensional Fokker-Planck numerical results has been found

    Consequences of sexual harassment in sport for female athletes

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    Sexual harassment research was first undertaken in the workplace and educational settings. Research on sexual harassment in sport is scarce but has grown steadily since the mid-1980s. Even so, very little is known about the causes and/or characteristics and/or consequences of sexual harassment in sport settings. This article reports on the findings from interviews with 25 elite female athletes in Norway who indicated in a prior survey (N =572) that they had experienced sexual harassment from someone in sport. The consequences of the incidents of sexual harassment that were reported were mostly negative, but some also reported that their experiences of sexual harassment had had no consequences for them. “Thinking about the incidents”, a “destroyed relationship to the coach”, and “more negative view of men in general” were the most often negative consequences mentioned. In addition, a surprising number had chosen to move to a different sport or to drop out of elite sport altogether because of the harassment

    Structure on Interplanetary Shock Fronts: Type II Radio Burst Source Regions

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    We present \emph{in situ} observations of the source regions of interplanetary (IP) type II radio bursts, using data from the Wind spacecraft during the period 1996-2002. We show the results of this survey as well as in-depth analysis of several individual events. Each event analyzed in detail is associated with an interplanetary coronal mass ejection (ICME) and an IP shock driven by the ICME. Immediately prior to the arrival of each shock, electron beams along the interplanetary magnetic field (IMF) and associated Langmuir waves are detected, implying magnetic connection to a quasiperpendicular shock front acceleration site. These observations are analogous to those made in the terrestrial foreshock region, indicating that a similar foreshock region exists on IP shock fronts. The analogy suggests that the electron acceleration process is a fast Fermi process, and this suggestion is borne out by loss cone features in the electron distribution functions. The presence of a foreshock region requires nonplanar structure on the shock front. Using Wind burst mode data, the foreshock electrons are analyzed to estimate the dimensions of the curved region. We present the first measurement of the lateral, shock-parallel scale size of IP foreshock regions. The presence of these regions on IP shock fronts can explain the fine structure often seen in the spectra of type II bursts.Comment: 19 pages, 5 figures. To be published in The Astrophysical Journa

    Combined Retrievals of Boreal Forest Fire Aerosol Properties with a Polarimeter and Lidar

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    Absorbing aerosols play an important, but uncertain, role in the global climate. Much of this uncertainty is due to a lack of adequate aerosol measurements. While great strides have been made in observational capability in the previous years and decades, it has become increasingly apparent that this development must continue. Scanning polarimeters have been designed to help resolve this issue by making accurate, multi-spectral, multi-angle polarized observations. This work involves the use of the Research Scanning Polarimeter (RSP). The RSP was designed as the airborne prototype for the Aerosol Polarimetery Sensor (APS), which was due to be launched as part of the (ultimately failed) NASA Glory mission. Field observations with the RSP, however, have established that simultaneous retrievals of aerosol absorption and vertical distribution over bright land surfaces are quite uncertain. We test a merger of RSP and High Spectral Resolution Lidar (HSRL) data with observations of boreal forest fire smoke, collected during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS). During ARCTAS, the RSP and HSRL instruments were mounted on the same aircraft, and validation data were provided by instruments on an aircraft flying a coordinated flight pattern. We found that the lidar data did indeed improve aerosol retrievals using an optimal estimation method, although not primarily because of the constraints imposed on the aerosol vertical distribution. The more useful piece of information from the HSRL was the total column aerosol optical depth, which was used to select the initial value (optimization starting point) of the aerosol number concentration. When ground based sun photometer network climatologies of number concentration were used as an initial value, we found that roughly half of the retrievals had unrealistic sizes and imaginary indices, even though the retrieved spectral optical depths agreed within uncertainties to independent observations. The convergence to an unrealistic local minimum by the optimal estimator is related to the relatively low sensitivity to particles smaller than 0.1 ( m) at large optical thicknesses. Thus, optimization algorithms used for operational aerosol retrievals of the fine mode size distribution, when the total optical depth is large, will require initial values generated from table look-ups that exclude unrealistic size/complex index mixtures. External constraints from lidar on initial values used in the optimal estimation methods will also be valuable in reducing the likelihood of obtaining spurious retrievals

    Does susceptibility to heat stress confound screening for drought tolerance in rice?

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    Drought affected rice areas are predicted to double by the end of this century, demanding greater tolerance in widely adapted mega-varieties. Progress on incorporating better drought tolerance has been slow due to lack of appropriate phenotyping protocols. Furthermore, existing protocols do not consider the effect of drought and heat interactions, especially during the critical flowering stage, which could lead to false conclusion about drought tolerance. Screening germplasm and mapping-populations to identify quantitative trait loci (QTL)/candidate genes for drought tolerance is usually conducted in hot dry seasons where water supply can be controlled. Hence, results from dry season drought screening in the field could be confounded by heat stress, either directly on heat sensitive processes such as pollination or indirectly by raising tissue temperature through reducing transpirational cooling under water deficit conditions. Drought-tolerant entries or droughtresponsive candidate genes/QTL identified from germplasm highly susceptible to heat stress during anthesis/flowering have to be interpreted with caution. During drought screening, germplasm tolerant to water stress but highly susceptible to heat stress has to be excluded during dry and hot season screening. Responses to drought and heat stress in rice are compared and results from field and controlled environment experiments studying drought and heat tolerance and their interaction are discussed

    'You were quiet - I did all the marching': Research processes involved in hearing the voices of South Asian girls

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    This article is available open access through the publisher’s website at the link below. Copyright @ 2011 A B Academic Publishers.This article provides insights into the outcomes of reflection following two interview approaches used to explore narratives of the lived, individual experiences of South-Asian girls living in West London. In attempting to illuminate and re-present the cultural experiences as told by these girls, the choice of interview approach became critical in allowing the voices to be effectively heard (Rogers, 2005). This article therefore considers how a semi-structured interview approach offered valuable insights into the girls' experiences but became constraining for both researcher and participant in unveiling the complexity and depth of their lives. These constraints emerged through reflection by both participants and researcher. As a result of reflexivity during the research process, the researcher moved towards the use of research conversations during the second phase of the study. Ultimately the study revealed how the girls felt empowered by the opportunity to narrate their individual experiences and tell of their lives. In narrating their reflections on being part of the research, there was a clear recognition that the process facilitated the articulation of new voices and ‘multi-voicedness’ (Moen, 2006

    Identification and validation of DOCK4 as a potential biomarker for risk of bone metastasis development in patients with early breast cancer.

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    Skeletal metastasis occurs in around 75% of advanced breast cancers, with the disease incurable once cancer cells disseminate to bone, but there remains an unmet need for biomarkers to identify patients at high risk of bone recurrence. This study aimed to identify such a biomarker and to assess its utility in predicting response to adjuvant zoledronic acid. We used quantitative proteomics (SILAC-MS), to compare protein expression in a bone-homed variant (BM1) of the human breast cancer cell line MDA-MB-231 with parental non-bone-homing cells to identify novel biomarkers for risk of subsequent bone metastasis in early breast cancer. SILAC-MS showed that Dedicator of cytokinesis protein 4 (DOCK4) was upregulated in bone-homing BM1 cells, confirmed by Western blotting. BM1 cells also had enhanced invasive ability compared with parental cells which could be reduced by DOCK4-shRNA. In a training Tissue Microarray (TMA) comprising 345 patients with early breast cancer, immunohistochemistry followed by Cox regression revealed that high DOCK4 expression correlated with histological grade (p=0.004) but not oestrogen receptor status (p=0.19) or lymph node involvement (p=0.15). A clinical validation TMA used tissue samples and the clinical database from the large AZURE adjuvant study (n=689). Adjusted Cox regression analyses showed that high DOCK4 expression in the control arm (no zoledronic acid) was significantly prognostic for first recurrence in bone (HR 2.13, 95%CI 1.06-4.30, p=0.034). No corresponding association was found in patients who received zoledronic acid (HR 0.812, 95%CI 0.176-3.76, p=0.790), suggesting that treatment with zoledronic acid may counteract the higher risk for bone relapse from high DOCK4-expressing tumours. High DOCK4 expression was not associated with metastasis to non-skeletal sites when these were assessed collectively. In conclusion, high DOCK4 in early breast cancer is significantly associated with aggressive disease and with future bone metastasis and is a potentially useful biomarker for subsequent bone metastasis risk

    Antimicrobial use in European acute care hospitals: results from the second point prevalence survey (PPS) of healthcare-associated infections and antimicrobial use, 2016 to 2017

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    Antimicrobial agents used to treat infections are life-saving. Overuse may result in more frequent adverse effects and emergence of multidrug-resistant microorganisms. In 2016-17, we performed the second point-prevalence survey (PPS) of healthcare-associated infections (HAIs) and antimicrobial use in European acute care hospitals. We included 1,209 hospitals and 310,755 patients in 28 of 31 European Union/European Economic Area (EU/EEA) countries. The weighted prevalence of antimicrobial use in the EU/EEA was 30.5% (95% CI: 29.2-31.9%). The most common indication for prescribing antimicrobials was treatment of a community-acquired infection, followed by treatment of HAI and surgical prophylaxis. Over half (54.2%) of antimicrobials for surgical prophylaxis were prescribed for more than 1 day. The most common infections treated by antimicrobials were respiratory tract infections and the most commonly prescribed antimicrobial agents were penicillins with beta-lactamase inhibitors. There was wide variation of patients on antimicrobials, in the selection of antimicrobial agents and in antimicrobial stewardship resources and activities across the participating countries. The results of the PPS provide detailed information on antimicrobial use in European acute care hospitals, enable comparisons between countries and hospitals, and highlight key areas for national and European action that will support efforts towards prudent use of antimicrobials

    The impact and estimation of uncertainty correlation for multi-angle polarimetric remote sensing of aerosols and ocean color

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    Multi-angle polarimetric (MAP) measurements contain rich information for characterization of aerosol microphysical and optical properties that can be used to improve atmospheric correction in ocean color remote sensing. Advanced retrieval algorithms have been developed to obtain multiple geophysical parameters in the atmosphere–ocean system, although uncertainty correlation among measurements is generally ignored due to lack of knowledge on its strength and characterization. In this work, we provide a practical framework to evaluate the impact of the angular uncertainty correlation from retrieval results and a method to estimate correlation strength from retrieval fitting residuals. The Fast Multi-Angular Polarimetric Ocean coLor (FastMAPOL) retrieval algorithm, based on neural-network forward models, is used to conduct the retrievals and uncertainty quantification. In addition, we also discuss a flexible approach to include a correlated uncertainty model in the retrieval algorithm. The impact of angular correlation on retrieval uncertainties is discussed based on synthetic Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) and Hyper-Angular Rainbow Polarimeter 2 (HARP2) measurements using a Monte Carlo uncertainty estimation method. Correlation properties are estimated using autocorrelation functions based on the fitting residuals from both synthetic AirHARP and HARP2 data and real AirHARP measurement, with the resulting angular correlation parameters found to be larger than 0.9 and 0.8 for reflectance and degree of linear polarization (DoLP), respectively, which correspond to correlation angles of 10 and 5∘. Although this study focuses on angular correlation from HARP instruments, the methodology to study and quantify uncertainty correlation is also applicable to other instruments with angular, spectral, or spatial correlations and can help inform laboratory calibration and characterization of the instrument uncertainty structure.</p
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