Optimization of heat transfer characteristics, flow distribution, and reaction processing for a microstructured reactor/heat-exchanger for optimal performance in platinum catalyzed ammonia oxidation

The present work is focused on the demonstration of the advantages of miniaturized reactor systems which are essential for processes where potential for considerable heat transfer intensification exists as well as for kinetic studies of highly exothermic reactions at near-isothermal conditions. The heat transfer characteristics of four different cross-flow designs of a microstructured reactor/heat-exchanger (MRHE) were studied by CFD simulation using ammonia oxidation on a platinum catalyst as a model reaction. An appropriate distribution of the nitrogen flow used as a coolant can decrease drastically the axial temperature gradient in the reaction channels. In case of a microreactor made of a highly conductive material, the temperature non-uniformity in the reactor is strongly dependent on the distance between the reaction and cooling channels. Appropriate design of a single periodic reactor/heat-exchanger unit, combined with a non-uniform inlet coolant distribution, reduces the temperature gradients in the complete reactor to less than 4degreesC, even at conditions corresponding to an adiabatic temperature rise of about 1400degreesC, which are generally not accessible in conventional reactors because of the danger of runaway reactions. To obtain the required coolant flow distribution, an optimization study was performed to acquire the particular geometry of the inlet and outlet chambers in the microreactor/heat-exchanger. The predicted temperature profiles are in good agreement with experimental data from temperature sensors located along the reactant and coolant flows. The results demonstrate the clear potential of microstructured devices as reliable instruments for kinetic research as well as for proper heat management in the case of highly exothermic reactions. (C) 2002 Elsevier Science B.V. All rights reserved.

Availability of complementary and alternative medicine for people with cancer in the British National Health Service: Results of a national survey

This study assessed access to Complementary and Alternative Medicine (CAM) therapies for people with cancer within the British National Health Service. CAM units were identified through an internet search in 2009. A total of 142 units, providing 62 different therapies, were identified: 105 (74.0%) England; 23 (16.2%) Scotland; 7 (4.9%) each in Wales and Northern Ireland. Most units provide a small number of therapies (median 4, range 1–20), and focus on complementary, rather than alternative approaches. Counselling is the most widely provided therapy (available at 82.4% of identified units), followed by reflexology (62.0%), aromatherapy (59.1%), reiki (43.0%), massage (42.2%). CAM units per million of the population varied between countries (England: 2.2; Wales: 2.3; Scotland: 4.8; Northern Ireland: 5.0), and within countries. Better publicity for CAM units, greater integration of units in conventional cancer treatment centres may help improve access to CAMs.

Class and Performance in the Age of Global Capitalism

This article addresses the relative absence of class-based analysis in theatre and performance studies, and suggests the reconfiguration of class as performance rather than as it is traditionally conceived as an identity predicated solely on economic stratification. It engages with the occlusion of class by the ascendancy of identity politics based on race, gender and sexuality and its attendant theoretical counterparts in deconstruction and post-structuralism, which became axiomatic as they displaced earlier methodologies to become hegemonic in the arts and humanities. The article proceeds to an assessment of the development of sociological approaches to theatre, particularly the legacy of Raymond Williams and Pierre Bourdieu. The argument concludes with the application of an approach which reconfigures class as performance to the production of Declan Hughes's play Shiver of 2003, which dramatizes the consequences of the dot.com bubble of the late 1990s for ambitious members of the Irish middle class.

Brain activity during ankle proprioceptive stimulation predicts balance performance in young and older adults

Proprioceptive information from the foot/ankle provides important information regarding body sway for balance control, especially in situations where visual information is degraded or absent. Given known increases in catastrophic injury due to falls with older age, understanding the neural basis of proprioceptive processing for balance control is particularly important for older adults. In the present study, we linked neural activity in response to stimulation of key foot proprioceptors (i.e., muscle spindles) with balance ability across the lifespan. Twenty young and 20 older human adults underwent proprioceptive mapping; foot tendon vibration was compared with vibration of a nearby bone in an fMRI environment to determine regions of the brain that were active in response to muscle spindle stimulation. Several body sway metrics were also calculated for the same participants on an eyes-closed balance task. Based on regression analyses, multiple clusters of voxels were identified showing a significant relationship between muscle spindle stimulation-induced neural activity and maximum center of pressure excursion in the anterior-posterior direction. In this case, increased activation was associated with greater balance performance in parietal, frontal, and insular cortical areas, as well as structures within the basal ganglia. These correlated regions were age- and foot-stimulation side-independent and largely localized to right-sided areas of the brain thought to be involved in monitoring stimulus-driven shifts of attention. These findings support the notion that, beyond fundamental peripheral reflex mechanisms, central processing of proprioceptive signals from the foot is critical for balance control.

White matter fractional anisotrophy predicts balance performance in older adults

Aging is characterized by brain structural changes that may compromise motor functions. In the context of postural control, white matter integrity is crucial for the efficient transfer of visual, proprioceptive and vestibular feedback in the brain. To determine the role of age-related white matter decline as a function of the sensory feedback necessary to correct posture, we acquired diffusion weighted images in young and old subjects. A force platform was used to measure changes in body posture under conditions of compromised proprioceptive and/or visual feedback. In the young group, no significant brain structure-balance relations were found. In the elderly however, the integrity of a cluster in the frontal forceps explained 21% of the variance in postural control when proprioceptive information was compromised. Additionally, when only the vestibular system supplied reliable information, the occipital forceps was the best predictor of balance performance (42%). Age-related white matter decline may thus be predictive of balance performance in the elderly when sensory systems start to degrade.