The large scale geometry of some metabelian groups

We study the large scale geometry of the upper triangular subgroup of PSL(2,Z[1/n]), which arises naturally in a geometric context. We prove a quasi-isometry classification theorem and show that these groups are quasi-isometrically rigid with infinite dimensional quasi-isometry group. We generalize our results to a larger class of groups which are metabelian and are higher dimensional analogues of the solvable Baumslag-Solitar groups BS(1,n)

Calculation of air supply rates and concentrations of airborne contamination in non-UDAF cleanrooms

This article reviews a series of scientific articles written by the authors, where the following topics were investigated in relation to non-unidirectional airflow cleanrooms. (1) The air supply rate required to obtain a specified concentration of airborne contamination. (2) The calculation of concentrations of airborne contaminants in different ventilation and dispersion of contamination situations. (3) The decay of airborne contamination (a) during the ‘clean up’ test described in Annex 1 of the EU Guidelines to Good Manufacturing Practice (2008); (b) during the recovery rate test described in Annex B12 of ISO 14644-3 (2005); (c) associated with clean areas, such as airlocks, to reduce airborne contamination before a door into a cleanroom is opened. Worked examples are provided to demonstrate the calculation methods to provide solutions to the above topics

An ethnography of a neighbourhood café: informality, table arrangements and background noise

Café society is something that many of us as customers and/or social theorists take for granted. Cafés are places where we are not simply served hot beverages but are also in some way partaking of a specific form of public life. It is this latter aspect that has attracted the attention of social theorists, especially Jürgen Habermas, and leads them to locate the café as a key place in the development of modernity. Our approach to cafés is to ‘turn the tables’ on theories of the public sphere and return to just what the life of a particular café consists of, and in so doing re-specify a selection of topics related to public spaces. The particular topics we deal with in a ‘worldly manner’ are the socio-material organisation of space, informality and rule following. In as much as we are able we have drawn on an ethnomethodological way of doing and analysing our ethnographic studies

Ventilation effectiveness in cleanrooms and its relation to decay rate, recovery rate, and air change rate

Non-unidirectional airflow cleanrooms are supplied with filtered air to minimise the contamination of a product or process by airborne contamination. The effectiveness of the ventilation system in providing the required type of airflow in the cleanroom that will minimise airborne contamination can be assessed by measuring ventilation effectiveness indexes. This article provides information on what ventilation effectiveness indexes are suitable for cleanrooms, and how they can be obtained by test methods in common use in cleanrooms. Three methods of measuring ventilation effectiveness are discussed, namely, the Contamination Removal Effectiveness (CRE) index, the Air Change Effectiveness (ACE) index and the Performance Index (PI), and it was considered that the ACE index and PI were the most suitable for use in cleanrooms. The decay rate and recovery rate of airborne contamination in relation to the air change rate in non-unidirectional cleanrooms is also considered, and it is demonstrated that when measured at the same location, the three rates are identical. Also considered is the measurement of these rates in cleanrooms and how they can be used to obtain the ACE index

Is the Referendum question a theological question?

Margaret Whyte’s essay (which was selected as winner of the Fraser Prize competition for 2014) puts forward the argument that the Referendum on Scottish independence raises highly relevant theological questions about nationhood, social welfare and justice, and the role of the church. She uses biblical, theological and ecclesiological material to present a balanced discussion of the question, taking in consideration of the current position of religion in society, and of ecumenical and inter-faith issues.Publisher PD

50-nm self-aligned and 'standard' T-gate InP pHEMT comparison: the influence of parasitics on performance at the 50-nm node

Continued research into the development of III-V high-electron mobility transistors (HEMTs), specifically the minimization of the device gate length, has yielded the fastest performance reported for any three terminal devices to date. In addition, more recent research has begun to focus on reducing the parasitic device elements such as access resistance and gate fringing capacitance, which become crucial for short gate length device performance maximization. Adopting a self-aligned T-gate architecture is one method used to reduce parasitic device access resistance, but at the cost of increasing parasitic gate fringing capacitances. As the device gate length is then reduced, the benefits of the self-aligned gate process come into question, as at these ultrashort-gate dimensions, the magnitude of the static fringing capacitances will have a greater impact on performance. To better understand the influence of these issues on the dc and RF performance of short gate length InP pHEMTs, the authors present a comparison between In0.7Ga0.3As channel 50-nm self-aligned and "standard" T-gate devices. Figures of merit for these devices include transconductance greater than 1.9 S/mm, drive current in the range 1.4 A/mm, and fT up to 490 GHz. Simulation of the parasitic capacitances associated with the self-aligned gate structure then leads a discussion concerning the realistic benefits of incorporating the self-aligned gate process into a sub-50-nm HEMT syste

Empirical modelling and simulation of transmission loss between wireless sensor nodes in gas turbine engines

Transmission loss measurements between a grid of hypothetical WSN node locations on the surface of a gas turbine engine are reported for eight frequencies at 1 GHz intervals in the frequency range 3.0 to 11.0 GHz. An empirical transmission loss model is derived from the measurements. The model is incorporated into an existing system channel model implemented using Simulink as part of a wider project concerning the development of WSNs for the testing and condition monitoring of gas turbine engines

The Impact of China's Market Reforms on the Health of Chinese Citizens: Examining Two Puzzles

China's post-1978 market reforms were accompanied by a drastic decline in the coverage of the Chinese population by medical insurance as well as by sharp increases in charges for medical treatments, tests, and prescriptions. Since the 1990s, these trends have produced widespread condemnation of the current Chinese medical care system for being too costly and unequal. This article attempts to answer two questions: 1) Why did changes in the healthcare system precipitated by market reforms not lead to the kind of deterioration in the health of Chinese citizens that market reforms produced in Eastern Europe and the former Soviet Union? 2) In view of the increased inequalities in access to, and insurance coverage for, medical care since 1978, and particularly the growing rural-urban gap, why do Chinese villagers and migrants rate their current health better than do urban citizens?Sociolog