210 research outputs found
Comparison of Simulation Codes for the Beam Dynamics of Low-Energy Ions
Results are presented of the simulation of low–energy ion dynamics with three different codes: KOBRA, IGUN and CPO. To share work between different codes one needs to be confident that they agree. For test cases, good agreement was found between the codes and analytical solutions. Where possible, results have been compared to experimental data from the CERN Laser Ion Source. These simulations are in general agreement with the data of the real beam line. c The following article has been submitted to Review of Scientific Instruments. After it is published, it will be found at http://ojps.aip.org/rsio/
Phase Rotation, Cooling And Acceleration Of Muon Beams: A Comparison Of Different Approaches
Experimental and theoretical activities are underway at CERN with the aim of
examining the feasibility of a very-high-flux neutrino source. In the present
scheme, a high-power proton beam (some 4 MW) bombards a target where pions are
produced. The pions are collected and decay to muons under controlled optical
condition. The muons are cooled and accelerated to a final energy of 50 GeV
before being injected into a decay ring where they decay under well-defined
conditions of energy and emittance.
We present the most challenging parts of the whole scenario, the muon
capture, the ionisation-cooling and the first stage of the muon acceleration.
Different schemes, their performance and the technical challenges are compared.Comment: LINAC 2000 CONFERENCE, paper ID No. THC1
The CERN laser-ion source
This paper describes the first results of a feasibility study undertaken at CERN to determine whether a laser-produced plasma can be used as a source of intense highly charged heavy ion beams. A variety of important measurements have been made, and the results are encouraging. Furthermore, a beam of highly charged light ions produced by the laser ion source has been accelerated successfully in a radio frequency quadrupole (RFQ) structur
Under-representation of males in the early years: the challenges leaders face
This article investigates why there appears to be an under-representation of males in comparison to their female colleagues in the Early Years (EY) sector, and the perception of male teachers progressing more quickly to leadership positions when they do enter this context. Using case studies of final year male students on an Initial Teacher Training (ITT) undergraduate degree course at one university, we attempt to analyse data on male under-representation in Early Years against contemporary theories of identity, power and leadership. Questionnaires and interviews were conducted with the male sample group and male senior leaders in primary schools to gain an overview as to the leadership support they needed and provided. Our tentative findings suggested that male trainees are happy to work in an Early Years context and take leadership positions, but the challenge for leaders is that male trainees require strong leadership mentoring processes to help overcome perceived contextual barriers
Ancient role of vasopressin/oxytocin-type neuropeptides as regulators of feeding revealed in an echinoderm.
BACKGROUND: Vasopressin/oxytocin (VP/OT)-type neuropeptides are well known for their roles as regulators of diuresis, reproductive physiology and social behaviour. However, our knowledge of their functions is largely based on findings from studies on vertebrates and selected protostomian invertebrates. Little is known about the roles of VP/OT-type neuropeptides in deuterostomian invertebrates, which are more closely related to vertebrates than protostomes. RESULTS: Here, we have identified and functionally characterised a VP/OT-type signalling system comprising the neuropeptide asterotocin and its cognate G-protein coupled receptor in the starfish (sea star) Asterias rubens, a deuterostomian invertebrate belonging to the phylum Echinodermata. Analysis of the distribution of asterotocin and the asterotocin receptor in A. rubens using mRNA in situ hybridisation and immunohistochemistry revealed expression in the central nervous system (radial nerve cords and circumoral nerve ring), the digestive system (including the cardiac stomach) and the body wall and associated appendages. Informed by the anatomy of asterotocin signalling, in vitro pharmacological experiments revealed that asterotocin acts as a muscle relaxant in starfish, contrasting with the myotropic actions of VP/OT-type neuropeptides in vertebrates. Furthermore, in vivo injection of asterotocin had a striking effect on starfish behaviour-triggering fictive feeding where eversion of the cardiac stomach and changes in body posture resemble the unusual extra-oral feeding behaviour of starfish. CONCLUSIONS: We provide a comprehensive characterisation of VP/OT-type signalling in an echinoderm, including a detailed anatomical analysis of the expression of both the VP/OT-type neuropeptide asterotocin and its cognate receptor. Our discovery that asterotocin triggers fictive feeding in starfish provides important new evidence of an evolutionarily ancient role of VP/OT-type neuropeptides as regulators of feeding in animals
Online Hate: From the Far-Right to the ‘Alt-Right’, and from the Margins to the Mainstream
In the 1990s and early 2000s, there was much discussion about the democratic and anti-democratic implications of the Internet. The latter particularly focused on the ways in which the far-right were using the Internet to spread hate and recruit members. Despite this common assumption, the American far-right did not harness the Internet quickly, effectively or widely. More recently, however, they have experienced a resurgence and mainstreaming, benefitting greatly from social media. This chapter examines the history of their use of the Internet with respect to: (1) how this developed in response to political changes and emerging technologies; (2) how it reflected and changed the status of such movements and their brand of hate; and (3) the relationship between online activity and traditional methods of communication
The breadth of primary care: a systematic literature review of its core dimensions
Background: Even though there is general agreement that primary care is the linchpin of effective health care delivery, to date no efforts have been made to systematically review the scientific evidence supporting this supposition. The aim of this study was to examine the breadth of primary care by identifying its core dimensions and to assess the evidence for their interrelations and their relevance to outcomes at (primary) health system level.
Methods: A systematic review of the primary care literature was carried out, restricted to English language journals reporting original research or systematic reviews. Studies published between 2003 and July 2008 were searched in MEDLINE, Embase, Cochrane Library, CINAHL, King's Fund Database, IDEAS Database, and EconLit.
Results: Eighty-five studies were identified. This review was able to provide insight in the complexity of primary care as a multidimensional system, by identifying ten core dimensions that constitute a primary care system. The structure of a primary care system consists of three dimensions: 1. governance; 2. economic conditions; and 3. workforce development. The primary care process is determined by four dimensions: 4. access; 5. continuity of care; 6. coordination of care; and 7. comprehensiveness of care. The outcome of a primary care system includes three dimensions: 8. quality of care; 9. efficiency care; and 10. equity in health. There is a considerable evidence base showing that primary care contributes through its dimensions to overall health system performance and health.
Conclusions: A primary care system can be defined and approached as a multidimensional system contributing to overall health system performance and health
CERN PS laser ion source development
CERN, together with ITEP and TRINITI (Russia), is developing a CO2 laser ion source. The key design parameters are: 1.4 1010 ions of Pb25+ in a pulse of 5.5 ms, with a 4-rms emittance of 0.2 10-6 rad m, working at a repetition rate of 1 Hz. This device is considered as one candidate source for LHC heavy ion operation. The status of the laser development, the experimental set-up of the source consisting of the target area and its illumination, the plasma expansion area and extraction, beam transport and ion pre-acceleration by an RFQ, will be given
Characterization of low molecular weight alkoxylated polymers using long column SFC/MS and an image analysis based quantitation approach
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