3,991 research outputs found

    Radially restricted linear energy transfer for high-energy protons: A new analytical approach

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    Radially restricted linear energy transfer (LET) is a basic physical parameter relevant to radiation biology and radiation protection. In this report a convenient method is presented for the analytical computation of this quantity without the need for complicated simulation. The method uses the energy-re-stricted LETL, as recently redefined in a 1993 ICRU draft document and supplements it by a relatively simple term that represents the energy of fast rays lost within distancer from the track core. The method provides a better fit than other models and is valid over the entire range of radial distance from track center to the maximum radial distance traveled by the most energetic secondary electrons.L r computed by this approach differs only a few percent from the values Contribution to the international symposium on heavy ions research: space, radiation protection and therapy, 21โ€“24 March 1994, Sophia-Antipolis, Franc

    Motor neglect associated with loss of action inhibition

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    Motor neglect, underuse of one side of the body not explained by weakness or sensory impairment, is a common consequence of stroke that is surprisingly little understood. Behavioural and neuroanatomical hallmarks of the disorder are investigated. Using a masked prime task, it was shown that when patients with left motor neglect plan to move their left hand, irrelevant right limb motor programmes intrude, causing delay. Lesion analysis reveals that such asymmetry of motor programming occurs after infarcts of the right putamen and motor association areas. This demonstration of failure to inhibit ipsilesional limb motor plans suggests potential benefit from interventions that might act to restore balance in action planning

    A survey exploring private farm advisor perspectives of agri-environment schemes : The case of England's Environmental Stewardship programme

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    Most stakeholder-based research concerning agri-environmental schemes (AES) derives from work engaging with farmers and land managers. Consequently, the voices and opinions of other actors involved in AES tends to be unrepresented in the wider literature. One group of actors that seem particularly overlooked in this respect are private (independent) farm advisors (i.e., the consultants contracted by farmers and land managers to advise-on AES and agronomic matters). To begin to rectify this knowledge gap we developed an exploratory online survey to explore private farm advisor perspectives in the UK; specifically, the situation in England and advisors' experience of Natural England's Environmental Stewardship programme. A total of 251 Natural England registered farm advisors (29.9%) completed our survey. The majority of these had knowledge and expertise in relation to two (31.5%) or three (42.2%) Environmental Stewardship schemes, with proficiency in ELS (93.4%) and HLS (82.8%) being the most common. On average, advisors had 9.6 ยฑ 5.6 yrs of experience and operated (75.3%) in a single region of England. Although our results concentrated upon a relatively simple set of initial topics of inquiry, the survey revealed a number of interesting findings. Firstly; for example, that in the opinion of the advisors working with farmers applying for Environmental Stewardship schemes, the 'knowledge-exchange encounter' occurring between themselves, their clients and Natural England is fundamental to the environmental effectiveness of these schemes as well as their farm business compatibility. Secondly, respondents suggested that beneath this 'encounter' lie tensions arising from the competing agendas and objectives of the different actors involved which can affect the content of agreements; for instance, farmer selection of management options versus Natural England's target environmental objectives. Farm advisors suggested that they had to negotiate this balance whilst also serving the needs of their clients. Thirdly, respondents raised issues concerning the complicated nature of scheme arrangements, both from their own and farmers' perspectives, as well as the adequacy of payments to cover input costs and matters regarding contractual compliance, all of which theyproposed affected farmer participation. Looking ahead, we believe that future AES should account for all of these issues in their design to aid long-term farmer participation, effective agreement implementation and beneficial environmental management

    Matching Conditions in Atomistic-Continuum Modeling of Materials

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    A new class of matching condition between the atomistic and continuum regions is presented for the multi-scale modeling of crystals. They ensure the accurate passage of large scale information between the atomistic and continuum regions and at the same time minimize the reflection of phonons at the interface. These matching conditions can be made adaptive if we choose appropriate weight functions. Applications to dislocation dynamics and friction between two-dimensional atomically flat crystal surfaces are described.Comment: 6 pages, 4 figure

    The potential for circular dichroism as an additional facile and sensitive method of monitoring low-molecular-weight heparins and heparinoids

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    The ultraviolet circular dichroism (CD) spectra of commercial low-molecular-weight heparins, heparinoids and other anticoagulant preparations have been recorded between 180 and 260 nm. Principal component analysis of the spectra allowed their differentiation into a number of groups related to the means of their production reflecting the structural changes introduced by each process. The findings suggest that CD provides a complementary technique for the rapid analysis of heparin preparations

    Drag Reduction by Polymers in Wall Bounded Turbulence

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    We address the mechanism of drag reduction by polymers in turbulent wall bounded flows. On the basis of the equations of fluid mechanics we present a quantitative derivation of the "maximum drag reduction (MDR) asymptote" which is the maximum drag reduction attained by polymers. Based on Newtonian information only we prove the existence of drag reduction, and with one experimental parameter we reach a quantitative agreement with the experimental measurements.Comment: 4 pages, 1 fig., included, PRL, submitte

    CASTNet: Community-Attentive Spatio-Temporal Networks for Opioid Overdose Forecasting

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    Opioid overdose is a growing public health crisis in the United States. This crisis, recognized as "opioid epidemic," has widespread societal consequences including the degradation of health, and the increase in crime rates and family problems. To improve the overdose surveillance and to identify the areas in need of prevention effort, in this work, we focus on forecasting opioid overdose using real-time crime dynamics. Previous work identified various types of links between opioid use and criminal activities, such as financial motives and common causes. Motivated by these observations, we propose a novel spatio-temporal predictive model for opioid overdose forecasting by leveraging the spatio-temporal patterns of crime incidents. Our proposed model incorporates multi-head attentional networks to learn different representation subspaces of features. Such deep learning architecture, called "community-attentive" networks, allows the prediction of a given location to be optimized by a mixture of groups (i.e., communities) of regions. In addition, our proposed model allows for interpreting what features, from what communities, have more contributions to predicting local incidents as well as how these communities are captured through forecasting. Our results on two real-world overdose datasets indicate that our model achieves superior forecasting performance and provides meaningful interpretations in terms of spatio-temporal relationships between the dynamics of crime and that of opioid overdose.Comment: Accepted as conference paper at ECML-PKDD 201

    Cisplatin-induced emesis: systematic review and meta-analysis of the ferret model and the effects of 5-HT3 receptor antagonists

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    PURPOSE: The ferret cisplatin emesis model has been used for ~30ย years and enabled identification of clinically used anti-emetics. We provide an objective assessment of this model including efficacy of 5-HT(3) receptor antagonists to assess its translational validity. METHODS: A systematic review identified available evidence and was used to perform meta-analyses. RESULTS: Of 182 potentially relevant publications, 115 reported cisplatin-induced emesis in ferrets and 68 were included in the analysis. The majority (nย =ย 53) used a 10ย mgย kg(โˆ’1) dose to induce acute emesis, which peaked after 2ย h. More recent studies (nย =ย 11) also used 5ย mgย kg(โˆ’1), which induced a biphasic response peaking at 12ย h and 48ย h. Overall, 5-HT(3) receptor antagonists reduced cisplatin (5ย mgย kg(โˆ’1)) emesis by 68% (45โ€“91%) during the acute phase (day 1) and by 67% (48โ€“86%) and 53% (38โ€“68%, all Pย <ย 0.001), during the delayed phase (days 2, 3). In an analysis focused on the acute phase, the efficacy of ondansetron was dependent on the dosage and observation period but not on the dose of cisplatin. CONCLUSION: Our analysis enabled novel findings to be extracted from the literature including factors which may impact on the applicability of preclinical results to humans. It reveals that the efficacy of ondansetron is similar against low and high doses of cisplatin. Additionally, we showed that 5-HT(3) receptor antagonists have a similar efficacy during acute and delayed emesis, which provides a novel insight into the pharmacology of delayed emesis in the ferret
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