Analysis and Evaluation of the Dynamic Performance of SMA Actuators for Prosthetic Hand Design

It is widely acknowledged within the biomedical engineering community that shape memory alloys (SMAs) exhibit great potential for application in the actuation of upper limb prosthesis designs. These lightweight actuators are particularly suitable for prosthetic hand solutions. A four-fingered, 12 degree-of-freedom prosthetic hand has been developed featuring SMA bundle actuators embedded within the palmar structure. Joule heating of the SMA bundle actuators generates sufficient torque at the fingers to allow a wide range of everyday tasks to be carried out. Transient characterization of SMA bundles has shown that performance/response during heating and cooling differs substantially. Natural convection is insufficient to provide for adequate cooling during elongation of the actuators. An experimental test-bed has been developed to facilitate analysis of the heat transfer characteristics of the appropriately sized SMA bundle actuators for use within the prosthetic hand design. Various modes of heat sinking are evaluated so that the most effective wire-cooling solution can be ascertained. SMA bundles of varying size will be used so that a generalized model of the SMA displacement performance under natural and forced cooling conditions can be obtained. The optimum cooling solution will be implemented onto the mechanical hand framework in future work. These results, coupled with phenomenological models of SMA behavior, will be used in the development of an effective control strategy for this application in future work.     

The effect of increased interrogation zone,reader antenna polarization and application factors in the performance of UHF RFID tag detection on modified atmosphere packaged meat

The effect of conveyor speed, test sample size, antenna to sample distance, antenna polarization and ideal tag location in relation to the coupling capabilities of ultra‐high frequency radio frequency identification on optimal reader antenna placement were studied. The influence of each individual factor and its interaction was determined using the general linear model analysis of variance. In decreasing order of significance of the variables tested were sample type (F = 4174.40, p < 0.0005), smaller samples preferred for coupling; distance (F = 863.83, p < 0.0005), where distance between sample and antenna should be kept to a minimum; inlay design (F = 167.82, p < 0.0005), where AD‐612 preformed best due to its large antenna area; and reader antenna polarization (F = 149.64, p < 0.0005), where circular polarization preformed better yet comparative advantage decreased with distance. A reader antenna offset of 95 mm, while not significant, (F = 1.73, p = 0.188) tended to decrease coupling capabilities of the system despite increasing the zone of influence. Ideal tag location on sample was found to be on the right, back and front face with y‐orientation proving superior than either x or z. A 190‐mm centre–to‐centre reader antenna offset resulted in a decrease in the average tag detection rate from 62 to 49% highlighting the importance of optimal reader antenna placement which needs to be confirmed if a similar result is to be obtained when a large number of tags are interrogated simultaneously. Copyright © 2010 John Wiley & Sons, Ltd.     

Chemical and Physical Sensing by Organic Field‐Effect Transistors and Related Devices

Organic semiconductor films are susceptible to noncovalent interactions, trapping and doping, photoexcitation, and dimensional deformation. While these effects can be detrimental to the performance of conventional circuits, they can be harnessed, especially in field‐effect architectures, to detect chemical and physical stimuli. This Review summarizes recent advances in the use of organic electronic materials for the detection of environmental chemicals, pressure, and light. The material features that are responsible for the transduction of the input signals to electronic information are discussed in detail.     

Enhancing the carbon sink in European agricultural soils: including trace gas fluxes in estimates of carbon mitigation potential

The possibility that the carbon sink in agricultural soils can be enhanced has taken on great political significance since the Kyoto Protocol was finalised in December 1997. The Kyoto Protocol allows carbon emissions to be offset by demonstrable removal of carbon from the atmosphere. Thus, forestry activities (Article 3.3) and changes in the use of agricultural soils (Article 3.4) that are shown to reduce atmospheric CO₂levels may be included in the Kyoto emission reduction targets. The European Union is committed to a reduction in CO₂ emissions to 92% of baseline (1990) levels during the first commitment period (2008–2012). We have shown recently that there are a number of agricultural land-management changes that show some potential to increase the carbon sink in agricultural soils and others that allow alternative forms of carbon mitigation (i.e. through fossil fuel substitution), but the options differ greatly in their potential for carbon mitigation. The changes examined were, (a) switching all animal manure use to arable land, (b) applying all sewage sludge to arable land, (c) incorporating all surplus cereal straw, (d) conversion to no-till agriculture, (e) use of surplus arable land to de-intensify 1/3 of current intensive crop production (through use of 1/3 grass/arable rotations), (f) use of surplus arable land to allow natural woodland regeneration, and (g) use of surplus arable land for bioenergy crop production. In this paper, we attempt for the first time to assess other (non-CO₂) effects of these land-management changes on (a) the emission of the other important agricultural greenhouse gases, methane and nitrous oxide, and (b) other aspects of the ecology of the agroecosystems. We find that the relative importance of trace gas fluxes varies enormously among the scenarios. In some such as the sewage sludge, woodland regeneration and bioenergy production scenarios, the inclusion of trace gases makes only a small (<10%) difference to the CO₂-C mitigation potential. In other cases, for example the no-till, animal manure and agricultural de-intensification scenarios, trace gases have a large impact, sometimes halving or more than doubling the CO₂-C mitigation potential. The scenarios showing the greatest increase when including trace gases are those in which manure management changes significantly. In the one scenario (no-till) where the carbon mitigation potential was reduced greatly, a small increase in methane oxidation was outweighed by a sharp increase in N₂O emissions. When these land-management options are combined to examine the whole agricultural land area of Europe, most of the changes in mitigation potential are small, but depending upon assumptions for the animal manure scenario, the total mitigation potential either increases by about 20% or decreases by about 10%, shifting the mitigation potential of the scenario from just above the EU's 8% Kyoto emission reduction target (98.9 Tg C y⁻¹) to just below it. Our results suggest that (a) trace gas fluxes may change the mitigation potential of a land management option significantly and should always be considered alongside CO₂-C mitigation potentials and (b) agricultural management options show considerable potential for carbon mitigation even after accounting for trace gas fluxes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Concluding causation from correlation: Comment on Burns and Spangler (2000).

This commentary critiques the study conducted by D. D. Burns and D. Spangler (2000) (see record 2000-13544-005) in which the relationship between homework compliance and therapy outcome was estimated using structural equation modeling (SEM). Although the authors, of the commentary advocate the use of SEM, they suggest greater caution in the indiscriminate endorsement of a causal relationship based on (a) correlational data and (b) retrospective accounts of the main predictor variable within a cross-sectional design. This discussion also highlights a need to address the issue of therapist competence in homework administration. The results of Burns and Spangler's report are consistent with existing empirical evidence suggesting that compliance with homework facilitates therapeutic outcome. However, the gold standard for determining causal inferences rests on prospective, experimental research rather than on retrospective, correlational models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Minimizing the Handoff Latency in Ad-Hoc Networks When Streaming Media to Mobile Devices

The number of mobile devices connecting to networks independently of a fixed point of attachment is increasing. These wireless networks differ in bandwidth, size and location of the coverage area, access costs and network characteristics. Mobile multimedia devices such as PDA's, palmtops and laptops will also vary greatly in size and processing power. The common denominator however, is that all these devices will require the optimal delivery of networked multimedia data.One interesting problem is the delay imposed upon mobile receivers when switching between wireless cells. We provide a solution to this in the form of an extension of Mobile IP's hand-off algorithm. Our solution involves the exploitation of mobility prediction to predict a mobile terminal's future location based on its previous history (i.e., the last cell that it has been in) and for the media stream to be already present and cached by next cells base station ready for receiving by the mobile device.We cater specifically for continuous media applications, which can be especially effected by severe degradation in quality due to movement between cells. We present the results of a series of simulations of the Mobile IP++ protocol, which demonstrate the effectiveness of the ad-hoc protocol when mobile hosts move in predictable patterns between cells.     

Attention processes in children with shunted hydrocephalus versus attention deficit-hyperactivity disorder.

Children with congenital hydrocephalus, children with attention deficit-hyperactivity disorder, and normal controls were evaluated with measures of focused attention (Visual Orienting and Detection Task), sustained attention (continuous performance test), and attention shifting (Wisconsin Card Sorting Test). Components from these tasks have been linked to attention systems mediated by anterior or posterior brain networks. Children with congenital hydrocephalus showed an inability to focus and shift attention, which specifically implicated impairment of the disengage and move components of the posterior brain attention system. Children with attention deficit- hyperactivity disorder displayed the expected performance patterns on measures of focused attention once their difficulties with sustained attention were taken into account. However, they showed problems with shifting and sustaining attention, which are commonly associated with the anterior brain attention system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The proof of the pudding: An illustration of the relative strengths of null hypothesis, meta-analysis, and Bayesian analysis.

Some methodologists have recently suggested that scientific psychology's overreliance on null hypothesis significance testing (NHST) impedes the progress of the discipline. In response, a number of defenders have maintained that NHST continues to play a vital role in psychological research. Both sides of the argument to date have been presented abstractly. The authors take a different approach to this issue by illustrating the use of NHST along with 2 possible alternatives (meta-analysis as a primary data analysis strategy and Bayesian approaches) in a series of 3 studies. Comparing and contrasting the approaches on actual data brings out the strengths and weaknesses of each approach. The exercise demonstrates that the approaches are not mutually exclusive but instead can be used to complement one another. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perfectionism as a predictor of subsequent adjustment: Evidence for a specific diathesis–stress mechanism among college students.

The relations among perfectionism, stress, subsequent psychological symptoms, and hopelessness were examined among 215 college students. Hierarchical regression analyses were conducted to determine whether dimensions of perfectionism (P. Hewitt & G. Flett, 1991) predicted psychological symptoms and hopelessness (1 month later), and the extent to which stress scores added incremental validity to these predictions. Results indicated that socially prescribed perfectionism was a significant predictor of both adjustment measures. In addition, stress accounted for a significant amount of additional variance in predicting adjustment beyond perfectionism. Consistent with a diathesis–stress model, a significant Perfectionism × Stress interaction was found in predicting scores on adjustment measures beyond perfectionism and stress. However, this interaction was only found for socially prescribed perfectionism. Results provide support for a specific diathesis–stress mechanism and important implications for developing specific interventions in working with perfectionistic college students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Getting past setup obstacles,and moving to implementation,for law firm ADR groups

In the second of two parts, Kevin R. Casey, of Malvern, Pa., provides the tools to establish a comprehensive law firm alternative dispute resolution department. He covers ways to address attorney ambivalence, and lists implementation steps that will help the prospects for a well‐rounded, profitable program