On the Optimum Dispersion of a Storage Ring for Electron Cooling with High Space Charge

With the intense electron beams used for cooling, matching of the ion and electron velocity over the largest possible fraction of the beam profile becomes important. In this situation, a finite dispersion from the ring in the cooling section can lead to an appreciable gain in the transverse cooling speed. Based on a simple model of the cooling force, an expression for the "optimum" dispersion as a function of the electron beam intensity, the momentum spread and other properties of the ion beam will be derived. This simple theory will be compared to measurements made on the Low Energy Ion Ring (LEIR) at CERN during 1997

An archaeology of psychological knowledge as technology of power in Africa

The relevance of psychology in Africa is increasingly debated by psychologists. The subject stands accused of continuing a colonial tradition of oppression through its Eurocentrism and failure to attend to the needs of African societies. The relevance debate raises questions around the relationship between power, knowledge, psychology, and African history. This study attempts to excavate the conditions of possibility of the debate, by construing an archaeology of psychological knowledge as technology of power in the African context. It assumes a constructivist stance, employs textual and narrative analogies, and follows Foucault's conceptualisation of the relation between power and knowledge. Five strata of knowledge emerging historically in Africa, each embodying distinctive approaches to knowledge, are described: Indigenous African knowledge, African Islamic knowledge, African Christianity, knowledges of Enlightenment, and knowledges of resistance. These knowledges, their psychological dimensions, as well as the circulation of power within and between them, are explored, and historical processes of subjugation and resistance highlighted. Western psychology, as technology of modern power, is situated within modernism and the narratives ofEnlightenment, which also provided the conditions of possibility of colonialism. The dominant narratives of relevance are related to those of African resistance and the limitations of psychology are conceptualised in terms of those pertaining to modernism. Possible postmodern avenues to the liberation of both psychology and its subjects, that are relevant to African contexts, are suggested.PsychologyD. Litt. et Phil. (Psychology

The Anatomical Society core embryology syllabus for undergraduate medicine

A modified Delphi methodology was used to develop a consensus regarding a series of learning outcome statements to act as the foundation of an undergraduate medical core embryology syllabus. A Delphi panel was formed by recruiting stakeholders with experience in leading undergraduate teaching of medical students. The panel (n = 18), including anatomists, embryologists and practising clinicians, were nominated by members of Council and/or the Education Committee of the Anatomical Society. Following development of an a priori set of learning outcome statements (n = 62) by the authors, panel members were asked in the first of a two‐stage process to ‘accept’, ‘reject’ or ‘modify’ each learning outcome, to propose additional outcomes if desired. In the second stage, the panel was asked to either accept or reject 16 statements which had either been modified, or had failed to reach consensus, during the first Delphi round. Overall, 61 of 62 learning outcome statements, each linked to examples of clinical conditions to provide context, achieved an 80% level of agreement following the modified Delphi process and were therefore deemed accepted for inclusion within the syllabus. The proposed syllabus allows for flexibility within individual curricula, while still prioritising and focusing on the core level of knowledge of embryological processes by presenting the essential elements to all newly qualified doctors, regardless of their subsequent chosen specialty

Liquid metal embrittlement studies on model systems wiht respect to the spallation target technology: the importance of nanometre-thick films

Liquid metal embrittlement (LME) is illustrated on the Cu-Bi and Cu-PbBi systems at 300 C using either constant strain-rate tests at 10(-4) s(-1) or constant load tests at 25% of yield stress. Intergranular penetration was studied in the Ni-Bi system at 700 C and was shown to result in the formation of slowly growing micrometre-thick and rapidly growing nanometre-thick films. Both induce very strong intergranular brittleness but only micrometre-thick films are visible by SEM on polished cross-sections. Nanometre-thick films were analysed by Auger electron spectroscopy after "in situ" fractures within the spectrometer; in particular, a series of analyses on an Ni bicrystal proved the constant thickness of this film over several hundreds of microns. The severity of embrittlement due to bismuth penetration was confirmed in the analysis of the Ni-PbBi system. Based on these results, it is underlined that technological systems like T91 steel/Pb or T91/PbBi should work at temperatures below the wetting transition temperature (T-W), i. e. in the temperature range where intergranular films can't form. If it is not the case, nanometre-thick films should be taken into account, both in the evaluation of the kinetics of embrittlement and in the modelling of intergranular penetration and LME

Generation of magnetic field by dynamo action in a turbulent flow of liquid sodium

We report the observation of dynamo action in the VKS experiment, i.e., the generation of magnetic field by a strongly turbulent swirling flow of liquid sodium. Both mean and fluctuating parts of the field are studied. The dynamo threshold corresponds to a magnetic Reynolds number Rm \sim 30. A mean magnetic field of order 40 G is observed 30% above threshold at the flow lateral boundary. The rms fluctuations are larger than the corresponding mean value for two of the components. The scaling of the mean square magnetic field is compared to a prediction previously made for high Reynolds number flows.Comment: 4 pages, 5 figure

Instrumentations optique lagragienne pour l'étude de la granulométrie d'un écoulement chargé en particules

Nous présentons 2 instrumentations optiques permettant de mesurer, de manière Lagrangienne, la granulométrie d'un écoulement chargé en particules ou en gouttelettes. Un montage d'holographie numérique en ligne est présenté pour l'étude de l'évaporation de gouttelettes dans écoulement turbulent. Un montage d'ombroscopie PTV est mis en place pour étudier la dissolution de particules solides dans un écoulement de type Von Karman. De plus, ces 2 techniques ont aussi l'avantage d'offrir une visualisation dynamique du champ thermique ou de concentration dans le sillage des objets étudiés

Penicillamine should not be used as initial therapy in Wilson's disease

No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34958/1/1002_ftp.pd

If you build it will they come? Park upgrades, park use and park-based physical activity in urban Cape Town, South Africa—The sun study

The development and upgrade of recreational public spaces are key government strategies to increase opportunities for physical activity (PA) and enhance social interaction and community cohesion. This study aimed to evaluate differences in park use and park-based PA in recently upgraded/developed parks (intervention, n = 4) against established parks (control, n = 4) and in regional parks in high- and low-income settings (n = 2). Additionally, associations between target area features, park use and PA were identified. Direct observation of park use and attributes was conducted using the System for Observing Play and Recreation in Communities (SOPARC) over four months. Despite more park users in intervention parks (2519 vs. 1432), control park visitors were 48% more likely to be engaged in PA (p < 0.001). Similarly, while high-income park users attracted more visitors (2135 vs. 1111), they were 79% less likely to be engaged in any PA compared with low-income park visitors. The likelihood of both use of and PA by gender and age differed by features. Active recreation features in intervention parks attracted more users than the same features in control parks. In this study, upgraded or newly developed parks attracted more visitors but not necessarily overall greater levels of physical activity

Evidence for a diffusion-based mechanism of liquid metal intergranular penetration : case study of a Ni-Bi model system

A model Ni-Bi system has been used to investigate intergranular penetration (IGP) phenomenon. All experiments have been done on Ni 26° bicrystal at 700°C using bismuth vapour condensation as a source of liquid bismuth. Such a procedure results at room temperature in either partial or total Liquid Metal Induced Embrittlement (LMIE) of a unique grain boundary, depending on the duration of liquid Bi / solid Ni contact at 700°C. Auger Electron Spectrometry (AES) and Rutherford Backscattering Spectrometry (RBS) have been used to measure the Bi concentration profile between the source of liquid bismuth and the penetration front. Two zones have been clearly identified : the first one of almost constant Bi concentration called nanometrethick film which is interpreted in terms of Fowler-Guggenheim multi-layer segregation under local equilibrium conditions and the second one with a progressive decrease of Bi concentration over a distance of the order of 20-200μm. Such a long transition zone, together with parabolic diffusion kinetics indicates diffusion-based mechanism of intergranular penetration as opposed to the direct grain boundary wetting