999 resultados para Cross drain


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The development of cold trap-based positron beams and new scattering techniques has recently enabled the ?rst measurements of state-resolved positron-impact vibrational excitation cross sections. These measurements revealed a number of features worth further consideration, such as relatively sharp increases near threshold. This paper describes a comparison of the magnitudes and shapes of these cross sections with the predictions of the Born-dipole model. Agreement of the magnitudes of the cross sections varies widely, ranging from reasonable to excellent agreement for CO2 and CF4 to poor agreement for CO and CH4. In contrast, the energy dependence of these cross sections in all these cases is close to that predicted by the Born model.

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In a recent paper [Phys. Rev. Lett. 88, 163202 (2002)] we established the threshold behavior of the cross section of positron-atom annihilation into two gamma quanta near the positronium (Ps)-formation threshold. Here, the near-threshold behavior of the positron 3 gamma annihilation cross section and its relation to the ortho-Ps-formation cross section are determined. We also analyze the feasibility of observing these effects by examining the effect of the ?nite-energy resolution of a positron beam on the threshold behavior.

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Cross-curricularity, literacy and critical literacy are currently promoted as components of a curriculum appropriate for the 21st century. The first two in particular are prescribed elements of classroom experience in Northern Ireland, which is the immediate context of this article, but also more widely in the UK. Teachers are implementing cross-curricular and inter-disciplinary initiatives, but rhetorical imperatives can translate into superficial realities. The reasons for this are explored, as are the reasons why inter-disciplinary studies, literacy across the curriculum and critical literacy are deemed to be of significance for education at the present time. The ‘Making Science: Making News’ project is described, in which Key Stage 3 Science and English classes worked together, with input from a research scientist and a journalist, to produce articles on space science which were published in local newspapers. The outcomes of the project are discussed from the perspectives of both teachers and learners. It is argued that this project is an example of genuine inter-disciplinary activity; that it went beyond literacy skills to a deeper development of scientific discourse; and that, through its media connection, there was potential for building an ongoing awareness in pupils of critical literacy and scientific literacy.

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With China's new Enterprise Bankruptcy Law (‘EBL 2006’) having come into effect on 1 June 2007, a critical issue arises as to the extent to which Article 5, as a cross-border provision, will strengthen creditors' rights across jurisdictions. In this paper attention will be paid in particular to how the Chinese People's Court is likely to exercise its discretion to grant recognition to a foreign court ruling, and vice versa. The paper will start with a brief introduction to the circumstances under which Article 5 came into being. The evolution of China's cross-border insolvency practices will be examined through an analysis of an inbound case of B&T (2002) as well as an outbound one of GITIC (2005). In spite of the fact that China has not adopted the UNCITRAL Model Law, essential factors deemed necessary to be considered by China's court and its counterparts in US and UK are to be highlighted throughout the paper. Although the effect of Article 5 remains to be seen, it will be critically analysed focusing on some controversial issues.

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Charge exchange (CE) plays a fundamental role in the collisions of solar- and stellar-wind ions with lunar and planetary exospheres, comets, and circumstellar clouds. Reported herein are absolute cross sections for single, double, triple, and quadruple CE of Feq+ (q = 5-13) ions with H2O at a collision energy of 7q keV. One measured value of the pentuple CE is also given for Fe9+ ions. An electron cyclotron resonance ion source is used to provide currents of the highly charged Fe ions. Absolute data are derived from knowledge of the target gas pressure, target path length, and incident and charge-exchanged ion currents. Experimental cross sections are compared with new results of the n-electron classical trajectory Monte Carlo approximation. The radiative and non-radiative cascades following electron transfers are approximated using scaled hydrogenic transition probabilities and scaled Auger rates. Also given are estimates of cross sections for single capture, and multiple capture followed by autoionization, as derived from the extended overbarrier model. These estimates are based on new theoretical calculations of the vertical ionization potentials of H2O up to H2O10+.

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This paper examines the finite sample properties of three testing regimes for the null hypothesis of a panel unit root against stationary alternatives in the presence of cross-sectional correlation. The regimes of Bai and Ng (2004), Moon and Perron (2004) and Pesaran (2007) are assessed in the presence of multiple factors and also other non-standard situations. The behaviour of some information criteria used to determine the number of factors in a panel is examined and new information criteria with improved properties in small-N panels proposed. An application to the efficient markets hypothesis is also provided. The null hypothesis of a panel random walk is not rejected by any of the tests, supporting the efficient markets hypothesis in the financial services sector of the Australian Stock Exchange.

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Objectives
To evaluate how involvement in life situations (participation) in children with cerebral palsy varies with type and severity of impairment and to investigate geographical variation in participation.

Design
Cross sectional study. Trained interviewers visited parents of children with cerebral palsy; multilevel multivariable regression related participation to impairments, pain, and sociodemographic characteristics.

Setting
Eight European regions with population registers of children with cerebral palsy; one further region recruited children from multiple sources.

Participants
1174 children aged 8-12 with cerebral palsy randomly selected from the population registers, 743 (63%) joined in the study; the further region recruited 75 children.

Main outcome measure
Children’s participation assessed by the Life-H questionnaire covering 10 main areas of daily life. Scoring ignored adaptations or assistance required for participation.

Results
Children with pain and those with more severely impaired walking, fine motor skills, communication, and intellectual abilities had lower participation across most domains. Type of cerebral palsy and problems with feeding and vision were associated with lower participation for specific domains, but the sociodemographic factors examined were not. Impairment and pain accounted for up to a sixth of the variation in participation. Participation on all domains varied substantially between regions: children in east Denmark had consistently higher participation than children in other regions. For most participation domains, about a third of the unexplained variation could be ascribed to variation between regions and about two thirds to variation between individuals.

Conclusions
Participation in children with cerebral palsy should be assessed in clinical practice to guide intervention and assess its effect. Pain should be carefully assessed. Some European countries facilitate participation better than others, implying some countries could make better provision. Legislation and regulation should be directed to ensuring this happens.