The network queueing system

Described is the implementation of a networked, UNIX based queueing system developed on contract for NASA. The system discussed supports both batch and device requests, and provides the facilities of remote queueing, request routing, remote status, queue access controls, batch request resource quota limits, and remote output return

A Morphological Study of Ceramic Hollow Fibre Membranes: A Perspective on Multifunctional Catalytic Membrane Reactors

In recent years ceramic membrane technology has advanced considerably and ceramic membranes are now being applied to a number of high temperature applications, in particular in the energy industry as membrane reactors. Due to the thermal stability of ceramic materials, development in this area is extremely promising as these applications cannot be realized using polymeric membrane technology. Although a wide range of ceramic materials have been developed and processing techniques have improved considerably, the high production cost and lack of control over membrane properties when fabrication processes are scaled up are prohibitive in the commercial application of ceramic membrane technology. However, by using a dry-wet spinning process and the combined phase inversion and sintering technique, novel asymmetric hollow fibre morphologies consisting of a porous sponge-like structure and finger-like macrovoids in which catalyst may be deposited can be prepared in a cost effective way. These asymmetric hollow fibres are prepared from raw materials and are suitable for use in catalytic membrane reactors. Fibre morphology is determined by the rheological properties of the ceramic spinning suspension as well as the parameters used during fibre spinning and the effect of sintering during heat treatment. A generic mechanism has been suggested for the formation of asymmetric structures and the parameters at each of these three stages have been varied systematically in order to predict and control hollow fibre structure. Hollow fibres prepared in this way have been characterized in terms of morphology, pore size distribution, porosity and mechanical strength in terms of their applicability to membrane reactor applications. The versatility of this preparation technique is demonstrated by the inclusion of a chapter describing a catalytic membrane reactor for hydrogen production by water-gas-shift as well as a reactor for the dehydrogenation of propane. It should also be noted that this reactor design could be applied to a number of other catalytic gas phase reactions

A controlled sintering process for more permeable ceramic hollow fibre membranes

In this study, a new controlled sintering process has been proposed to improve the water permeation of asymmetric alumina hollow fibre membranes. In this process, polymer binder (PESf) in precursor fibres is purposely pre-treated in static air at selected temperatures (400-600. °C) to have it partially removed, prior to be converted into carbon in a second sintering step (1450. °C) under an oxygen free environment. During the second sintering step, proper bounding between ceramic particles takes place, while the growth of ceramic grains is effectively suppressed due to the presence of carbon. The carbon in the voids formed by particle packing also acts as a pore structure "stabilizer" and can be removed easily via subsequent thermal treatment in static air at 800. °C. Compared to the membranes with the same asymmetric structure and sintered in static air only (i.e. normal sintering), the membranes sintered using the new controlled sintering process shows water permeation flux is approximately 13 times higher, together with comparable mechanical strength. Moreover, this original concept of using the polymer binder to design the pore structure of ceramic membranes can be transferred to other inorganic materials

Implementation and validation of a CubeSat laser transmitter

The paper presents implementation and validation results for a CubeSat-scale laser transmitter. The master oscillator power amplifier (MOPA) design produces a 1550 nm, 200mW average power optical signal through the use of a directly modulated laser diode and a commercial fiber amplifier. The prototype design produces high-fidelity M-ary pulse position modulated (PPM) waveforms (M=8 to 128), targeting data rates > 10 Mbit/s while meeting a constraining 8W power allocation. We also present the implementation of an avalanche photodiode (APD) receiver with measured transmitter-to-receiver performance within 3 dB of theory. Via loopback, the compact receiver design can provide built-in self-test and calibration capabilities, and supports incremental on-orbit testing of the design

Introduction to the Special Issue on End-to-End Speech and Language Processing

The eleven papers in this special section focus on end-to-end speech and language processing (SLP) which is a series of sequence-to-sequence learning problems. Conventional SLP systems map input to output sequences through module-based architectures where each module is independently trained. These have a number of limitations including local optima, assumptions about intermediate models and features, and complex expert knowledge driven steps. It can be difficult for non-experts to use and develop new applications. Integrated End-to-End (E2E) systems aim to simplify the solution to these problems through a single network architecture to map an input sequence directly to the desired output sequence without the need for intermediate module representations. E2E models rely on flexible and powerful machine learning models such as recurrent neural networks. The emergence of models for end-to-end speech processing has lowered the barriers to entry into serious speech research. This special issue showcases the power of novel machine learning methods in end-to-end speech and language processing

Understanding concepts of generalism and specialism amongst medical students at a research-intensive London Medical School

Background Many prominent UK medical organisations have identified a need for more generalist clinicians to address the complex requirements of an aging society. We sought to clarify attitudes towards “Specialists” and “Generalists” amongst medical students and junior doctors at Imperial College School of Medicine. Methods A survey exploring medical students’ beliefs was followed up by qualitative analysis of focus groups of medical students and Imperial-graduate foundation year doctors. Results First year medical students associated specialists with academia and higher income, and generalists with ease of training and job availability. Senior (Years 5/6) medical students associated specialists even more firmly with broader influence and academic work, whilst generalists were assigned lower prestige but the same workload as specialists. The medical student focus group discussed concepts of Generalism pertaining only to Primary Care. In contrast, the foundation year doctor focus group revealed that Generalism was now seen to include some hospital care, and the perception that generalists sat lower in a knowledge hierarchy had been challenged. Conclusion Perceptions that Generalism is associated with lower prestige in the medical profession are already present at the very start of medical school and seem to be reinforced during undergraduate training. In early postgraduate clinical practice, the perceived knowledge and prestige hierarchy lessens. These findings can help inform curriculum redesign and the promotion of Generalism as a rewarding career aspiration

A proper understanding of Millikan

Ruth Millikan’s teleological theory of mental content is complex and often misunderstood. This paper motivates and clarifies some of the complexities of the theory, and shows that paying careful attention to its details yields answers to a number of common objections to teleological theories, in particular, the problem of novel mental states, the problem of functionally false beliefs, and problems about indeterminacy or multiplicity of function

Local sales restrictions significantly reduce the availability of menthol tobacco: findings from four Minnesota cities

BACKGROUND In 2017 and 2018, Minneapolis, St. Paul, Duluth and Falcon Heights, Minnesota were among the first US cities to restrict the sale of menthol tobacco to adult-only stores. The study examined changes in the availability and marketing of these products following policy implementation. METHODS Retail store audits were conducted approximately 2 months pre-policy and post-policy implementation. Tobacco retail stores (n=299) were sampled from tobacco licensing lists in Minneapolis, St. Paul, Duluth and Falcon Heights, as well as six comparison cities without menthol policies. The presence of menthol tobacco was assessed, along with the number of interior and exterior tobacco ads and promotions at each store. RESULTS The majority of policy intervention stores (grocery, convenience stores and pharmacies) were compliant (Minneapolis, 84.4%; Duluth, 97.5%; and St. Paul and Falcon Heights, 100.0%) and did not sell menthol tobacco. In contrast, menthol tobacco was available in all comparison city stores, and most (96.0%) exempted tobacco shops and liquor stores post-policy implementation. Two Minneapolis convenience stores added interior tobacco shops, allowing them to continue selling menthol tobacco. Significant decreases in menthol tobacco marketing post-policy were observed in the stores' interior in Minneapolis, St. Paul and Duluth (p<0.001) and on the stores' exterior in Duluth (p=0.023). CONCLUSIONS Findings demonstrate high rates of compliance, indicating that sales restrictions can significantly reduce the availability of menthol tobacco. However, challenges to policy adherence underscore the need for continued monitoring and enforcement action

Bonding in Functionalized Aziridines: Nitrogen-15 and Carbon-13 Studies

Two isomeric pairs of cis- and trans-1-cyclohexyl-2-phenyl-3-benzoylaziridines have been synthesized: (1) with a nitrogen-15 labelled nitrogen, and (2) with carbon-13 labelled ring carbons. The carbon-13 to X (where X=nitrogen-15, carbon-13 or hydrogen-I) spin-spin coupling constants were measured and interpreted in terms of stereoelectronic effects. X-ray crystallographic data (earlier determined for cisand trans-1-cyclohexyl-2-phenyl-3-(p-toluyl)aziridines)1 appear in good agreement with the NMR data. Bonding is discussed for the three-ring itself (NMR studies) and for its substituents (X-ray studies). It is concluded that stereochemical interaction of the Van der Waals type is an important determinant of aziridine bond length. Three-ring to carbonyl hyperconjugation is correlated with stereoelectronic interactions in the trans isomer