1,721,051 research outputs found
Spallation is not the only Fruit: Producing Neutrons using Low Energy Fusion Reactions
No full textCommercially there is a growing interest in applications of neutrons. Currently the majority of neutron sources are based at research institutions from either reactors or spallation sources. Smaller portable sources contain either fissile isotope or sealed fusors are available, although they either use or produce tritium, or other long lived decay products. As an alternative to the large facilities and the radio toxicology of current portable sources research is being performed with an aim to produce a fusion based neutron source with neither of these concerns. We show that MCNPX is able to accurately reproduce (p; n) reactions for a number of light elements. Simulations of low energy proton reactions with light nuclei simulated with MCNPX and Geant4 are compared with experiment
Fusion Based Neutron Sources for Security Applications: Energy Optimisation
No full textThere is a growing interest in the use of neutrons for na- tional security. The majority of work on security focuses on the use of either sealed tube DT fusors or fission sources, e.g. Cf-252. Fusion reactions enable the energy of the neu- tron beam to be chosen to suit the application, rather than the application being chosen based on the available neu- tron beam energy. In this paper we discuss simulations of fusion reactions demonstrating the broad range of energies available and methods for adapting the neutron beam en- ergy produced by target/projectile combinations
Fusion Based Neutron Sources for Security Applications: Neutron Techniques
No full textThe current reliance on X-Rays and intelligence for na- tional security is insufficient to combat the current risks of smuggling and terrorism seen on an international level. There are a range of neutron based security techniques which have the potential to dramatically improve national security. Neutron techniques can be broadly grouped into neutron in/neutron out and neutron in/photon out tech- niques. The use of accelerator based fusion devices will potentially enable to wide spread application of neutron se- curity techniques due to the potential for much safer oper- ation than that offered by fission or sealed tube sources. In this paper we discuss some of the neutron security tech- niques available and the advantages they present
Osteoma cutis in Albright`s Hereditary Osteodystrophy
No full textAlbright`s hereditary osteodystrophy is an inherited syndrome that encompasses endocrinologic anomaly of pseudohypoparathyroidim of less commonly, pseudo-pseudohypoparathyroidism and various physical stigmata such as mental retardation, short stature, skeletal anomaly of the hands, abnormal dentition, round facies, and osteoma cutis. Primary osteoma cutis in this syndrome presents at birth or in early infancy, preceding most of the other manifestations. This case is a typical presentation with osteoma cutis as the sole initial manifestation. Rather unfamiliar to dermatologists, Albright`s hereditary osteodystrophy still deserves to be included in the differentials when an isolated case of osteoma cutis presents in a young child.ope
Albright′s Hereditary Osteodystrophy: A Constellation of Clinical Features
No full textPseudohypoparathyroidism (PHP) is an inherited metabolic disorder characterized by end-organ resistance to the action of PTH (Parathyroid Hormone). There are four types of PHPs namely Ia, lb, Ic and II. PHP Ia is associated with a constellation of clinical features referred to as Albright′s Hereditary Osteodystroohy (AHO). The oral manifestation of AHO found in the literature includes aplasia and or enamel hypoplasia, late tooth eruption and enlarged radicular channels susceptible to caries. Here, we are reporting a rare case of a 14-year-old girl with Albrigt′s hereditary osteodystrophy with disintinctive oral manifesitations
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Preparations for upgrading the RF systems of the PS Booster
No full textThe accelerators of the LHC injector chain need to be upgraded to provide the HL-LHC beams. The PS Booster, the first synchrotron in the LHC injection chain, uses three different RF systems (first, second and up to tenth harmonic) in each of its four rings. As part of the LHC Injector Upgrade the current ferrite RF systems will be replaced with broadband Finemet cavities, increasing the flexibility of the RF system. A Finemet test cavity has been installed in Ring 4 to investigate its effect on machine performance, especially beam stability, during extensive experimental studies. Due to large space charge impedance Landau damping is lost through most of the cycle in single harmonic operation, but is recovered when using the second harmonic and controlled longitudinal emittance blow-up. This paper compares beam parameters during acceleration with and without the Finemet test cavity. Comparisons were made using beam measurements and simulations with the BLonD code based on a full PS Booster impedance model. This work, together with simulations of future operation, have provided input for the decision to adopt a fully Finemet RF system
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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