Laser interferometric measurement of ion electrode shape and charge exchange erosion

A projected fringe profilometry system was applied to surface contour measurements of an accelerator electrode from an ion thrustor. The system permitted noncontact, nondestructive evaluation of the fine and gross structure of the electrode. A 3-D surface map of a dished electrode was generated without altering the electrode surface. The same system was used to examine charge exchange erosion pits near the periphery of the electrode to determine the depth, location, and volume of material lost. This electro-optical measurement system allowed rapid, nondestructive, digital data acquisition coupled with automated computer data processing. In addition, variable sensitivity allowed both coarse and fine measurements of objects having various surface finishes

Requirements for long-life operation of inert gas hollow cathodes: Preliminary report

An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10(exp -3)sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode

Structural and thermal response of 30 cm diameter ion thruster optics

Tabular and graphical data are presented which are intended for use in calibrating and validating structural and thermal models of ion thruster optics. A 30 cm diameter, two electrode, mercury ion thruster was operated using two different electrode assembly designs. With no beam extraction, the transient and steady state temperature profiles and center electrode gaps were measured for three discharge powers. The data showed that the electrode mount design had little effect on the temperatures, but significantly impacted the motion of the electrode center. Equilibrium electrode gaps increased with one design and decreased with the other. Equilibrium displacements in excess of 0.5 mm and gap changes of 0.08 mm were measured at 450 W discharge power. Variations in equilibrium gaps were also found among assemblies of the same design. The presented data illustrate the necessity for high fidelity ion optics models and development of experimental techniques to allow their validation

The sensory screen: phenomenology of visual perception in early European avant-garde film

At the beginning of the twentieth century, certain artists, writers, and philosophers became intrigued by the profound ways in which filmic images could pervade aspects of modern thought and experience. For them, film had the potential to reveal radical new dimensions of sensory phenomena. The early development of avant-garde film-making in Europe is culturally crucial not only for its historical and conceptual context of creative transition, but also for its dynamic exploration of processes of visual perception. The central objective of this thesis is to expose and engage these profound perceptual issues within the specific sphere of graphic abstract film. The structural formation of the thesis entails the confluencing of material for analysis into a sequence of key areas comprising the central components of avant-garde cinematic visualisation. The visual implications of each area are analysed in specific depth, whilst acknowledging their respective interactivity. Significantly, the research applies analytic theories of phenomenology in order to focus incisively upon relevant early European avant-garde filmic imagery. The potential vitality of a phenomenological theorisation of early avant-garde film resides not only within their historical contemporaneity, but at the epistemological level of the mind's cognitive engagement with the realms of creative visualisation. It is a system of analysis which aims to establish a nuanced phenomenological theory of visual perception as a matter of prime sustenance to historically crucial cinematic art forms

Evaluating MI512: An information literacy course for PhD students

The purpose of this paper is to provide an overview of a six-week information literacy course for research students that was redesigned following the librarians undertaking the Postgraduate Certificate in Teaching in Higher Education. The paper presents a case study and evaluation of the impact of a teaching programme. Findings — Research students appreciate and value the expertise of library staff and are prepared to devote considerable time to an information literacy programme. The programme received excellent feedback. There is no summative assessment associated with the course and so no quantitative measure of improvement in learning. The paper provides a model programme other librarians can adapt for use at their own institution. Extended doctoral level information literacy courses are relatively uncommon and demonstrates the benefit of this type of course, to research

Inhibition of cell proliferation rather than of cell lysis as a measure of immune reactivity in embryo-antigen-challenged mice.

An assay system is described in which effector cells added along with suitable target cells inhibit, in a quantitative fashion, the subsequent uptake of 3H-thymidine by those target cells. Effector cells active in this assay, using embryonic fibroblast cells as targets, develop spontaneously in cultures of mouse lymphoid cells, but are apparently different from those described earlier by investigators of activity in cytotoxic assays. Further evidence is presented to show the development of spleen-derived effector cells with cytostatic activity (for embryonic fibroblast target cells) in mice during the course of normal pregnancy, or growth of spontaneously appearing mammary adenocarcinomas. Indeed, such effector cells can also be found within the growing solid mass itself. Different populations of tumour cells isolated from a solid tumour apparently differ in their susceptibility to growth inhibition by tumour-bearer-derived cytostatic effector cells, a phenomenon which may be related to metastatic spread of tumour cells

Tumour-cell susceptibility to cytotoxic or cytostatic effector cells in vitro and the regulation of tumour-cell growth in vivo.

Tumour-cell growth in lung nodules after i.v. transfer to sublethally irradiated mice has been followed after adoptive transfer of different populations of lymphoid cells. Spleen cells deliberately immunized in vitro and in vivo against stimulator cells bearing embryo-associated antigens and which are cytostatic in vitro for targets bearing such antigens, can diminish the number of lung nodules found after i.v. transfer. In contrast, cytotoxic (in vitro) spleen cells, while capable of diminishing local (s.c.) growth of tumour cells, cannot control systemic tumour growth. Within a given solid tumour mass, the subpopulations resistant to cytostatic effector cells in vitro are the ones most likely to produce lung colonies after adoptive transfer in vivo, though they show no more local (s.c.) growth than to cytostatic-sensitive cells in vivo

Making co-enrolment feasible for randomised controlled trials in paediatric intensive care.

Enrolling children into several trials could increase recruitment and lead to quicker delivery of optimal care in paediatric intensive care units (PICU). We evaluated decisions taken by clinicians and parents in PICU on co-enrolment for two large pragmatic trials: the CATCH trial (CATheters in CHildren) comparing impregnated with standard central venous catheters (CVCs) for reducing bloodstream infection in PICU and the CHIP trial comparing tight versus standard control of hyperglycaemia

4-Formyl-2-nitrophenyl 3-nitro-2-methylbenzoate

In the title formyl nitro aryl benzoate derivative, CH NO, the benzene rings form a dihedral angle of 4.96(3)°. The mean plane of the central ester group, C-O-C-(=O)-C (r.m.s. deviation = 0.0484Å), is twisted away from the formyl nitro aryl and benzoate rings by 46.61(5) and 49.93(5)°, respectively. In the crystal, the molecules are packed forming C-H⋯O interactions in chains which propagate along [010]. Edge-fused R 3(15) rings are generated along this direction