Assessment of a prototype battery operated wax-knife for domiciliary and surgery use

The aims of this study were to examine a prototype battery operated wax-knife, assess the extent to which manufacturer's claims have been achieved and determine its potential for clinical use. The mean time required for the wax-knife to achieve an operating temperature of 150 degrees C was 20.2(+/-4.3) s. The mean operating temperature of the ceramic blade was 155.4(+/-3.9) degrees C, range 150 degrees C to 162 degrees C. The mean usage time following full battery recharge was 42 (+/-2) minutes. The wax-knife provided a direct heating tool which retained many of the characteristics of the traditional wax-knife and was suitable for use in the surgery and in domiciliary situations.     

A 2.5n lower bound on the monotone network complexity of T 3 n

Summary The k-th threshold function, T _k ⁿ , is defined as: where x _i{0,1} and the summation is arithmetic. We prove that any monotone network computing T _3/n(x ₁,...,x _n) contains at least 2.5n-5.5 gates.This research was supported by the Science and Engineering Research Council of Great Britain, UK     

Group‐in‐a‐Box Meta‐Layouts for Topological Clusters and Attribute‐Based Groups: Space‐Efficient Visualizations of Network Communities and Their Ties

An important part of network analysis is understanding community structures like topological clusters and attribute‐based groups. Standard approaches for showing communities using colour, shape, rectangular bounding boxes, convex hulls or force‐directed layout algorithms remain valuable, however our Group‐in‐a‐Box meta‐layouts add a fresh strategy for presenting community membership, internal structure and inter‐cluster relationships. This paper extends the basic Group‐in‐a‐Box meta‐layout, which uses a Treemap substrate of rectangular regions whose size is proportional to community size. When there are numerous inter‐community relationships, the proposed extensions help users view them more clearly: (1) the Croissant–Doughnut meta‐layout applies empirically determined rules for box arrangement to improve space utilization while still showing inter‐community relationships, and (2) the Force‐Directed layout arranges community boxes based on their aggregate ties at the cost of additional space. Our free and open source reference implementation in NodeXL includes heuristics to choose what we have found to be the preferable Group‐in‐a‐Box meta‐layout to show networks with varying numbers or sizes of communities. Case study examples, a pilot comparative user preference study (nine participants), and a readability measure‐based evaluation of 309 Twitter networks demonstrate the utility of the proposed meta‐layouts.     

Austenite stability in Fe–Mn–Si-based shape memory alloys

The stability of austenite in a number of Fe–Mn–Si-based shape memory alloys has been investigated. It was found that a grain boundary precipitate of BCC structure is formed over a wide range of alloy compositions and heat treatment temperatures. This grain boundary phase has been identified as the chi (χ) phase. Although up to 3 vol.% of the grain boundary precipitate was generated by isothermal aging in the range 500–800 °C, it was found not to markedly affect the mechanical properties or the shape memory effect. Nano-indentation indicated that the hardness and strength of the parent and precipitate phase are very similar, as are their compositions.     

Effect of curing characteristics on residual stress generation in polymethyl methacrylate bone cements

Residual stresses resulting from the shrinkage of polymethyl methacrylate (PMMA) bone cement have been implicated in the formation of cracks in cement mantles following total hip arthroplasty. This study investigates whether two such cements, with differentiated solidification characteristics (i.e. working and setting times), display significant differences in their residual stress characteristics in an experiment designed to replicate the physical conditions of total hip arthroplasty. Experiments were performed using a representative femoral construct to measure and compare the temperatures and residual strains developed for standard PMMA cement mantles (CMW 1 Gentamicin) and slow curing cement mantles (SmartSet HV Gentamicin) during and following polymerization. These experimental results revealed no statistically significant difference (t-test, p > 0.05) for peak exotherm temperature and residual strain levels between the cements (measured after 3 h). The tailored polymerization characteristics of the slow-curing cement do not significantly affect residual stress generation, compared with the standard cement. It is often considered that residual stresses significantly relax following polymerization and before biomechanical loads are first applied during rehabilitation (up to 3 days later). This was examined for durations of 18 h to 3 days. Axial strains in the model femur and stem reduced by averages of 5.5 and 7.9 per cent respectively, while hoop strains in the stem exhibited larger reductions. An axisymmetric transient thermoelastic finite element model of the experiment was developed, allowing residual stresses to be predicted based on differential scanning calorimetry (DSC) measurements of the heat released throughout the exothermic curing reaction. The model predictions closely replicated the experimental measurements of both temperature and residual strain at 3 h, suggesting that residual strains can be fully accounted for by the thermal contraction mechanism associated with cooling after solidification.     

Mechanical and thermal behaviour of an acrylic bone cement modified with a triblock copolymer

The basic formulation of an acrylic bone cement has been modified by the addition of a block copolymer, Nanostrength^® (NS), in order to augment the mechanical properties and particularly the fracture toughness of the bone cement. Two grades of NS at different levels of loading, between 1 and 10 wt.%, have been used. Mechanical tests were conducted to study the behaviour of the modified cements; specific tests measured the bend, compression and fracture toughness properties. The failure mode of the fracture test specimens was analysed using scanning electron microscopy (SEM). The effect of NS addition on the thermal properties was also determined, and the polymerisation reaction using differential scanning calorimetry. It was observed that the addition of NS produced an improvement in the fracture toughness and ductility of the cement, which could have a positive contribution by reducing the premature fracture of the cement mantle. The residual monomer content was reduced when the NS was added. However this also produced an increase in the maximum temperature and the heat delivered during the polymerisation of the cement.     

The computational complexity of ideal semantics

We analyse the computational complexity of the recently proposed ideal semantics within both abstract argumentation frameworks (afs) and assumption-based argumentation frameworks (abfs). It is shown that while typically less tractable than credulous admissibi-lity semantics, the natural decision problems arising with this extension-based model can, perhaps surprisingly, be decided more efficiently than sceptical preferred semantics. In particular the task of finding the unique ideal extension is easier than that of deciding if a given argument is accepted under the sceptical semantics. We provide efficient algorithmic approaches for the class of bipartite argumentation frameworks and, finally, present a number of technical results which offer strong indications that typical problems in ideal argumentation are complete for the class of languages decidable by polynomial time algorithms allowed to make non-adaptive queries to a C oracle, where C is an upper bound on the computational complexity of deciding credulous acceptance: C=np for afs and logic programming (lp) instantiations of abfs; for abfs modelling default theories.     

Automation of cytokine flow cytometry assays

Cytokine flow cytometry (CFC) is a multiparameter assay of antigen-specific T cell function, potentially useful in the monitoring of experimental vaccines and progression of infectious diseases and cancer. Automation of CFC assays would greatly facilitate their use in clinical trials and involves several components. We describe here the migration of these assays to 96-well plates, the use of sample-handling robotics, and the use of lyophilized antigen and antibody plates to help automate CFC. Together, these elements can produce an integrated system capable of walkaway automation of an entire assay, resulting in the reproducible processing of potentially hundreds of samples per day. Implementation of such systems has begun to be undertaken by our group and others.     

A meta‐analysis of sodium profiling techniques and the impact on intradialytic hypotension

Introduction Hemodialysis has improved in recent years, however, despite such improvements, intra‐dialytic hypotensive episodes still persist which can lead to a reduction in the overall effectiveness of the treatment. Profiling sodium levels during dialysis can improve vascular refilling and therefore may prevent hypotensive events. A number of profiling methods exist and this meta‐analysis set out to examine the effectiveness of these methods. Methods To assess the effectiveness of hemodialysis sodium profiling techniques. A review and meta‐analysis analytical framework was used. A search was conducted using Medline, Embase and CINAHL, Scopus and Web of Knowledge between 1946 and 2014 of published English‐language peer reviewed randomized control studies. In total 10 articles were retrieved and included in the review. All data was abstracted with a standardized data collection form. Stata 11.2 (Stata Corp) was used to analyse the data. Actual numbers of hypotensive events were pooled between studies. Analysis of subgroups was performed on sodium profile type. The data were further investigated using meta‐regression. Publication bias was also tested. Findings Stepwise profiling was shown to be statistically significantly effective in reducing intradialytic episodes. Results demonstrated that linear sodium profiling was not effective in reducing hypotensive events during dialysis. Discussion This review has shown that using stepwise profiling is more effective at reducing intra‐dialytic symptoms than other profiling methods. There was no evidence that linear profiling method was any more effective than conventional dialysis and in fact the results showed the reverse.     

Factors controlling volatile organic compounds in dwellings in Melbourne,Australia

This study characterized indoor volatile organic compounds (VOCs) and investigated the effects of the dwelling characteristics, building materials, occupant activities, and environmental conditions on indoor VOC concentrations in 40 dwellings located in Melbourne, Australia, in 2008 and 2009. A total of 97 VOCs were identified. Nine VOCs, n‐butane, 2‐methylbutane, toluene, formaldehyde, acetaldehyde, d‐limonene, ethanol, 2‐propanol, and acetic acid, accounted for 68% of the sum of all VOCs. The median indoor concentrations of all VOCs were greater than those measured outdoors. The occupant density was positively associated with indoor VOC concentrations via occupant activities, including respiration and combustion. Terpenes were associated with the use of household cleaning and laundry products. A petroleum‐like indoor VOC signature of alkanes and aromatics was associated with the proximity of major roads. The indoor VOC concentrations were negatively correlated (P < 0.05) with ventilation. Levels of VOCs in these Australian dwellings were lower than those from previous studies in North America and Europe, probably due to a combination of an ongoing temporal decrease in indoor VOC concentrations and the leakier nature of Australian dwellings.