Optimising Channel Assignments for Private Mobile Radio Networks in the UHF 2 Band

Private mobile radio (PMR) services are widely used in business and emergency applications. Typically, these services use the UHF 2 band (450–470 MHz). In order to comply with continental practice, the provision of these services in the UK is to be realigned and a new operational assignment will be generated in 2005. However, this can only be achieved with an appropriate model and the ability to make assignments for large regional networks. The purpose of this paper is to bring our experiences of this problem to the wireless arena. We explain the model used when making assignments for UK PMR networks and identify existing techniques and theory which are appropriate for this problem. We demonstrate that improved assignments and estimates of spectral requirements for large operational services can be found.     

Geometric control and tuneable pore size distribution of buckypaper and buckydiscs

The fabrication of buckypaper from unfunctionalised multi-walled carbon nanotubes (MWCNTs) without the aid of surfactants or surface modification techniques is accomplished through a novel and quick frit compression method. The dimensions can be controlled through the size of the syringe housing and the through the mass of carbon nanotubes added. Their thicknesses are typically much larger than surfactant-cast buckypaper and range from 120 μm up to 650 μm; buckypaper with thicknesses larger than 500 μm we call buckydiscs. Buckypaper and buckydiscs are mechanically robust to handle, flexible, stable in solvents and possess larger porosities than Triton-X100 cast buckypaper. They also exhibit a memory effect when bending wetted samples, returning to their former geometry on drying. Buckypaper and buckydiscs were studied by mercury intrusion porosimetry to reveal a defined distribution of mesopores and small macropores that is, along with their density and apparent free volume, dependant on the casting solvent and therefore tuneable. Moreover, the frit compression system also allows control over the 3-dimensional geometry of the buckydiscs during the casting process.     

Formulation of Controlled Release Matrices by Granulation with a Polymer Dispersion

The objective of this work was to incorporate an ethylcellulose-based controlled-release coating suspension (Surelease, Colorcon) within a tablet matrix to provide a release controlling mechanism. Anhydrous theophylline, chlorpheniramine maleate, and acetaminophen were selected as model drug entities. Surelease dispersion was incorporated as the granulating agent either to the drug entity alone or to a blended mixture of drug and filler. Control batches included simple aqueous granulations and direct compression mixtures. Tablets were prepared on a single stroke tablet press. Dissolution was performed by the USP Method I (rotating basket) in purified water for the granulations and the resulting tablets. The uncompressed granulations did not exhibit prolonged release. In general, tablets prepared with the polymer suspension as the granulating agent were non-disintegrating, and exhibited slower dissolution than the control tablets. Release profiles were affected by drug concentration and excipient levels. By the dissolution method selected, complete drug release for the various formulations ranged from less than 1 hour to greater than 12 hours. The use of the polymer dispersion appears to enhance the processing characteristics of some materials, and to provide the formulator with control over drug release.     

Student Responses to Activities Designed to Develop Generic Professional Skills

This paper reports on student responses to a range of assessment activities in a final-year engineering unit. Existing assessment activities were supplemented with new activities, the overall aim being to link the assessment activities more effectively to the material being studied, and to develop a range of generic skills important in professional engineering practice. A class survey was undertaken at the beginning of the semester to establish the initial attitudes to the new assessment activities. This was followed up with an end-of-semester survey to determine the change in perceived value of the assessment activities, and to collect student feedback regarding the activities. The perceived value of the assessment activities was determined using a Likert rating scale, while student feedback was collected using open-ended questions. The assessment activities evaluated were group work, case study investigation, report writing, oral presentation, group self-assessment, industrial interviews, and written reflective journals. The responses indicate that engineering students value a range of assessment activities. They value highly visits to real engineering organizations, and—contrary to popular belief—value and enjoy oral presentation exercises.     

"Preexposure and extinction effects of lithium chloride induced taste-potentiated aversions for spatially contiguous auditory food cues in rats": Correction to Ellins and von Kluge (1987).

Reports an error in "Preexposure and extinction effects of lithium chloride induced taste-potentiated aversions for spatially contiguous auditory food cues in rats" by Stuart R. Ellins and Silvia von Kluge (Behavioral Neuroscience, 1987[Apr], Vol 101[2], 164-169). The aforementioned article contains errors in the last paragraph of the Results section, none of which change the results of the experiment. The corrected paragraph sections are provided in the erratum. (The following abstract of the original article appeared in record 1987-24095-001.) Taste potentiated illness-induced aversions for noisy food were studied in Sprague-Dawley rats. The rats ate from receptacles containing salty food and a contiguous tone produced by speakers under the food followed by lithium chloride injections. In preference tests, the rats then avoided noisy food in favor of quiet food followed by extinction and spontaneous recovery of the auditory aversion over repeated nonreinforced trials. Other rats were given either 4 or 10 days of exposure to the noisy food prior to taste-toxicosis treatment. None of these rats subsequently avoided noisy food. The importance of spatial contiguity and methodological variation in associating nongustatory food cues with illness is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

THE RELATION OF STRUCTURE AND COMPOSITION TO THERMAL EFFICIENCY OF REFRACTORIES WHEN USED IN REGENERATORS1

This study shows the relative rates of heat transmission in typical clay, silica, diaspore, fused alumina and silicon carbide refractories, when used as checker brick. It is shown that by lowering the porosity of checker brick an increase in efficiency is obtained by virtue of its greater heat capacity, which is a function of the weight and specific heat of the material. The glazing of a clay brick does not appreciably impair its efficiency in regeneration, as is sometimes thought, as shown by experiment and as explained by the fact that the greatest part of the heat leaves the surface of the brick by convection and this is affected only by the surface area, which is not appreciably changed by glazing.     

一个用于取得符号IEC 61508组织性功能安全认证的方法论第一部分:制定策略和确定实施范围

IEC 61508和IEC 61511为那些涉及在危险的与安全相关的环境下运营,同时想证明自身在功能安全管理方面有合规能力和资质的企业设立了一个全球通用的标准.为证明对这些标准的遵循,许多企业都选择通过制定一个战略目标来获得一个第三方权威机构的认证.做到这一点对企业来说是一项重要的成就,它除了要求一个全面完善的工作程序和出色的技术资源,还要求对标准有全面深入的理解、取得最高管理层的支持、需要对安全生命周期与该机构相关的各个阶段有清晰的认识.本文简要介绍了某国际级的安全系统集成商在获取符合IEC 61508标准的第三方功能安全认证的道路上所采用的战略.     

Using full matching to estimate causal effects in nonexperimental studies: Examining the relationship between adolescent marijuana use and adult outcomes.

Matching methods such as nearest neighbor propensity score matching are increasingly popular techniques for controlling confounding in nonexperimental studies. However, simple k:1 matching methods, which select k well-matched comparison individuals for each treated individual, are sometimes criticized for being overly restrictive and discarding data (the unmatched comparison individuals). The authors illustrate the use of a more flexible method called full matching. Full matching makes use of all individuals in the data by forming a series of matched sets in which each set has either 1 treated individual and multiple comparison individuals or 1 comparison individual and multiple treated individuals. Full matching has been shown to be particularly effective at reducing bias due to observed confounding variables. The authors illustrate this approach using data from the Woodlawn Study, examining the relationship between adolescent marijuana use and adult outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)