Pulsar magnetospheres: numerical simulations of large amplitude electron-positron oscillations

The numerical simulation of non-linear electron-positron oscillations is reported, showing the evolution of the electric field and the plasma number density for large amplitude disturbances. Sharp density gradients and changes in the oscillation frequency are demonstrated, and a new analytical framework is presented to illustrate these phenomena, particularly in the context of pulsar plasmas

Sliding wear of a self-mated thermally sprayed chromium oxide coating in a simulated PWR water environment

Bearing surfaces in the primary circuit of pressurized water reactors (PWR) are prone to damage due to aggressive chemical and tribological conditions under which they operate, and a wide range of materials have been examined in this regard. One of the most promising candidates is chromium oxide in the form of a thermally spayed coating, and in this work, the behaviour of a commercially available Cr2O3 coating in self-mated sliding was considered. Tests consisted of a number of start-stop cycles of sliding between a crowned pin and a rotating disc in a water environment in an autoclave in an attempt to simulate the most aggressive phase of bearing run-up and run-down. Wear and damage mechanisms were examined at temperatures from ambient up to 250 C (a representative PWR environment). Samples were characterized before and after wear testing using mass measurements, profilometry, X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS). Across the temperature range, wear was mild, with no evidence of coating delamination. A five-fold increase in wear was observed between 80 C and 250 C (with wear depths of generally less than 8 µm being observed on the disc samples even at the higher temperature), despite there being only very small changes in hardness of the coating over the same temperature range. Debris was observed on the wear tracks following testing, with the evidence together suggesting that this debris was a very fine-grained mixture of Cr2O3 and amorphous -CrOOH, a corrosion product of Cr2O3

The role of microstructural development in the hydrothermal corrosion of cast and HIPed Stellite 6 analogues in simulated PWR conditions

The corrosion behaviour of cast and HIPed Stellite 6 analogue materials in PWR-simulating conditions was investigated. The cast alloy exhibited localised corrosion at the boundary between the matrix and the M7C3 carbides, with this being attributed to chromium depletion in the matrix associated with the carbide growth. In contrast, the HIPed alloy exhibited no localised corrosion. The carbon content of the cast Stellite 6 analogue was right at the top end of the range indicated in the Stellite 6 specification: this results in a high fraction of carbides and a general depletion of the chromium content of the matrix

DETERMINATION OF INTERSTITIAL SOLID-SOLUBILITY LIMIT IN TANTALUM AND IDENTIFICATION OF THE PRECIPITATE PHASES

Solid-solubility limits at 1500, 1000, snd 500/sup o/C for carbon, nitrogen, and oxygen in high-punity tantalum were determined by x-ray lattice- parameter methods. For carbon, the solubility was found to be 0.17 at. % at 1500/sup o/C and less than 0.07 at. % at l00/sup o/C. A nitrogen solubility of 3.70 at. % at l500/sup o/C decreased linearly with temperature to 2.75 at. % at 1000/sup o/C and 1.8 at. % at 500/sup o/C. In the case of oxygen, the solubility was found to be 3.65 at. % at 1500/sup o/C, 1.95 at. % at l0O0/sup o/ C, and 2.5 at. % at 500/sup o/C. The phases Ta/sub 2/, the lowtemperature modificstion of Ta/sub 2/O/sub 5/, and Ta/sub x/N of unknown coznposition hut which has a superlattice structure based upon the oniginsl body-centered-cubic tantalum lattice were identified is the initisl precipitates in the respective systems. (auth

Illicit Exploitation of Natural Resources

Article 28A(1)(13) of the Protocol to the Statute of the African Court of Justice and Human Rights lists ‘Illicit exploitation of natural resources’ as a criminal offence within the Court’s jurisdiction. In conjunction with the new mandate of the African Court, which includes the exercise of jurisdiction over corporations for the first time in an international treaty, the prohibition of ‘illicit exploitation of natural resources’ creates an offence with especially sharp teeth, for businesspeople, their corporations, military actors and politicians. The crime constitutes an important innovation in international law, since it offers a distinct legal basis for prosecution of a wider array of acts covered by the war crime of pillage. Nonetheless, it also comes with a set of major limitations, not the least of which is its great vagueness. This chapter offers a critical doctrinal overview of the seven sub-offences that fall within the wider banner of this new crime of Illicit Exploitation, simultaneously pointing to a range of interpretative possibilities that might accord with recent thinking about the relationship between law and resource predation.Exploring the Frontiers of International La

Development and Assessment of a Patient-Centered Care Curriculum

The purpose of this paper is to chronicle the development and implementation of a pilot offering of the patient-centered care (PCC) curriculum sponsored by a partnership of schools of allied health and nursing and a local health care system. The objective of this interdisciplinary track is to increase the competency of allied health and nursing graduates to function in health care teams in both PCC and non-PCC hospital environments, thus improving the effectiveness of patient care. The elective track consists of two courses; a third course is under consideration. Students and faculty participating in the elective track were surveyed to assess their attitudes toward change and patient-centered care. Generally, participants believed that they could work well together but were not convinced of the viability of the PCC. Although the curriculum is still in its implementation stage and the nursing participation became minimal, this study aids in understanding opinions of nursing and allied health faculty and students regarding a new PCC curriculum

A comparison of the galling wear behaviour of PVD Cr and electroplated hard Cr thin films

Electroplated hard chromium (EPHC) is used in many industries as a wear and corrosion resistant coating. However, the long term viability of the electroplating process is at risk due to legislation regarding the toxic chemicals used. The physical vapour deposition (PVD) process has been shown to produce chromium and chromium-based coatings that could be a possible alternative for EPHC in some applications. This study investigates the microstructure and properties of two PVD chromium coatings as a possible alternative to EPHC to provide resistance to galling. Two PVD deposition processes are investigated, namely electron beam PVD (EBPVD) and unbalanced magnetron sputtering (UMS). Galling wear tests were performed according to ASTM G98-17. The results show that the two PVD coatings are of similar hardness, surface roughness and exhibit similar scratch behaviour. However, the galling wear resistance of the coating deposited by UMS is approximately ten times that of the EBPVD coating, and similar to that of the EPHC. X-ray diffraction reveals that the EBPVD chromium coating has a strong preferred orientation of the {200} planes parallel to the coating surface whilst in the UMS PVD coating, preferred orientations of the {110} and {211} planes parallel to the surface are observed. The EPHC does not exhibit relative peak intensities which conform to the International Centre for Diffraction Data (ICDD) powder diffraction pattern consistent with chromium. The crystal orientation of the PVD chromium coatings appears to play a significant role in influencing galling resistance

Decision by sampling

We present a theory of decision by sampling (DbS) in which, in contrast with traditional models, there are no underlying psychoeconomic scales. Instead, we assume that an attribute’s subjective value is constructed from a series of binary, ordinal comparisons to a sample of attribute values drawn from memory and is its rank within the sample. We assume that the sample reflects both the immediate distribution of attribute values from the current decision’s context and also the background, real-world distribution of attribute values. DbS accounts for concave utility functions; losses looming larger than gains; hyperbolic temporal discounting; and the overestimation of small probabilities and the underestimation of large probabilities

Carbohydrate carbon sources induce loss of flocculation of an ale-brewing yeast strain

Aims: To identify the nutrients that can trigger the loss of flocculation under growth conditions in an ale-brewing strain, Saccharomyces cerevisiae NCYC 1195. Methods and Results: Flocculation was evaluated using the method of Soares, EX. and Vroman, A. [Journal of Applied Microbiology (2003) 95, 325]. Yeast growth with metabolizable carbon sources (glucose, fructose, galactose, maltose or sucrose) at 2% (w/v), induced the loss of flocculation in yeast that had previously been allowed to flocculate. The yeast remained flocculent when transferred to a medium containing the required nutrients for yeast growth and a sole nonmetabolizable carbon source (lactose). Transfer of flocculent yeast into a growth medium with ethanol (4% v/v), as the sole carbon source did not induce the loss of flocculation. Even the addition of glucose (2% w/v) or glucose and antimycin A (0.1 mg lˉ¹) to this culture did not bring about loss of flocculation. Cycloheximide addition (15 mglˉ¹) to glucose-growing cells stopped flocculation loss. Conclusions: Carbohydrates were the nutrients responsible for stimulating the loss of flocculation in flocculent yeast cells transferred to growing conditions. The glucose-induced loss of flocculation required de novo protein synthesis. Ethanol prevented glucose-induced loss of flocculation. This protective effect of ethanol was independent of the respiratory function of the yeast. Significance and Impact of the Study: This work contributes to the elucidation of the role of nutrients in the control of the flocculation cycle in NewFlo phenotype yeast strains.Instituto Politécnico do Porto (IPP) - Fundo de Apoio à Investigação - Project P24/96 , P24/97.Programa Plurianual de Unidades de I&D-CIEA/ ISEP