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

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

Optically controlled grippers for manipulating micron-sized particles

We report the development of a joystick controlled gripper for the real-time manipulation of micron-sized objects, driven using holographic optical tweezers (HOTs). The gripper consists of an arrangement of four silica beads, located in optical traps, which can be positioned and scaled in order to trap an object indirectly. The joystick can be used to grasp, move (lateral or axial), and change the orientation of the target object. The ability to trap objects indirectly allows us to demonstrate the manipulation of a strongly scattering micron-sized metallic particle

Modelling the cost-effectiveness of public awareness campaigns for the early detection of non-small-cell lung cancer

Background: Survival rates in lung cancer in England are significantly lower than in many similar countries. A range of Be Clear on Cancer (BCOC) campaigns have been conducted targeting lung cancer and found to improve the proportion of diagnoses at the early stage of disease. This paper considers the cost-effectiveness of such campaigns, evaluating the effect of both the regional and national BCOC campaigns on the stage distribution of non-small-cell lung cancer (NSCLC) at diagnosis. Methods: A natural history model of NSCLC was developed using incidence data, data elicited from clinical experts and model calibration techniques. This structure is used to consider the lifetime cost and quality-adjusted survival implications of the early awareness campaigns. Incremental cost-effectiveness ratios (ICERs) in terms of additional costs per quality-adjusted life-years (QALYs) gained are presented. Two scenario analyses were conducted to investigate the role of changes in the ‘worried-well’ population and the route of diagnosis that might occur as a result of the campaigns. Results: The base-case theoretical model found the regional and national early awareness campaigns to be associated with QALY gains of 289 and 178 QALYs and ICERs of d13 660 and d18 173 per QALY gained, respectively. The scenarios found that increases in the ‘worried-well’ population may impact the cost-effectiveness conclusions. Conclusions: Subject to the available evidence, the analysis suggests that early awareness campaigns in lung cancer have the potential to be cost-effective. However, significant additional research is required to address many of the limitations of this study. In addition, the estimated natural history model presents previously unavailable estimates of the prevalence and rate of disease progression in the undiagnosed population

Symmetric sequence processing in a recurrent neural network model with a synchronous dynamics

The synchronous dynamics and the stationary states of a recurrent attractor neural network model with competing synapses between symmetric sequence processing and Hebbian pattern reconstruction is studied in this work allowing for the presence of a self-interaction for each unit. Phase diagrams of stationary states are obtained exhibiting phases of retrieval, symmetric and period-two cyclic states as well as correlated and frozen-in states, in the absence of noise. The frozen-in states are destabilised by synaptic noise and well separated regions of correlated and cyclic states are obtained. Excitatory or inhibitory self-interactions yield enlarged phases of fixed-point or cyclic behaviour.Comment: Accepted for publication in Journal of Physics A: Mathematical and Theoretica

Splittings of generalized Baumslag-Solitar groups

We study the structure of generalized Baumslag-Solitar groups from the point of view of their (usually non-unique) splittings as fundamental groups of graphs of infinite cyclic groups. We find and characterize certain decompositions of smallest complexity (`fully reduced' decompositions) and give a simplified proof of the existence of deformations. We also prove a finiteness theorem and solve the isomorphism problem for generalized Baumslag-Solitar groups with no non-trivial integral moduli.Comment: 20 pages; hyperlinked latex. Version 2: minor change

A canonical ensemble approach to graded-response perceptrons

Perceptrons with graded input-output relations and a limited output precision are studied within the Gardner-Derrida canonical ensemble approach. Soft non- negative error measures are introduced allowing for extended retrieval properties. In particular, the performance of these systems for a linear and quadratic error measure, corresponding to the perceptron respectively the adaline learning algorithm, is compared with the performance for a rigid error measure, simply counting the number of errors. Replica-symmetry-breaking effects are evaluated.Comment: 26 pages, 10 ps figure

Geospatial analysis and living urban geometry

This essay outlines how to incorporate morphological rules within the exigencies of our technological age. We propose using the current evolution of GIS (Geographical Information Systems) technologies beyond their original representational domain, towards predictive and dynamic spatial models that help in constructing the new discipline of "urban seeding". We condemn the high-rise tower block as an unsuitable typology for a living city, and propose to re-establish human-scale urban fabric that resembles the traditional city. Pedestrian presence, density, and movement all reveal that open space between modernist buildings is not urban at all, but neither is the open space found in today's sprawling suburbs. True urban space contains and encourages pedestrian interactions, and has to be designed and built according to specific rules. The opposition between traditional self-organized versus modernist planned cities challenges the very core of the urban planning discipline. Planning has to be re-framed from being a tool creating a fixed future to become a visionary adaptive tool of dynamic states in evolution

Viscoelastic properties of differentiating blood cells are fate- and function-dependent

This is the final version of the article. Available from the publisher via the DOI in this record.Although cellular mechanical properties are known to alter during stem cell differentiation, understanding of the functional relevance of such alterations is incomplete. Here, we show that during the course of differentiation of human myeloid precursor cells into three different lineages, the cells alter their viscoelastic properties, measured using an optical stretcher, to suit their ultimate fate and function. Myeloid cells circulating in blood have to be advected through constrictions in blood vessels, engendering the need for compliance at short time-scales (minutes), compared to undifferentiated cells. These findings suggest that reduction in steady-state viscosity is a physiological adaptation for enhanced migration through tissues. Our results indicate that the material properties of cells define their function, can be used as a cell differentiation marker and could serve as target for novel therapies.Funding: The authors acknowledge financial support by the Cambridge Commonwealth Trust (to AEE; http://www.cambridgetrusts.org), the Medical Research Council (to KC and JG; grant number: 94185; http://www.mrc.ac.uk), the Human Frontier Science Program (to GW and JG; grant number: RGP0015/2009-C; http:// www.hfsp.org) and the European Research Council (to JG; grant number: 282060; http://erc.europa.eu)