Evaluation of Corrosion Fatigue Behaviour of Laser-welded NiTi Alloys using Bending Rotation Fatigue Test in Simulated Body Fluid

Shape memory NiTi alloys have been used extensively for medical device applications such as orthopedic, dental, vascular and cardiovascular devices on account of their unique shape memory effect (SME) and super-elasticity (SE). Laser welding is found to be the most suitable method used to fabricate NiTi-based medical components. However, the performance of laser-welded NiTi alloys under corrosive environments is not fully understood and a specific focus on understanding the corrosion fatigue behaviour is not evident in the literature. This study reveals a comparison of corrosion fatigue behaviour of laser-welded and bare NiTi alloys using bending rotation fatigue (BRF) test which was integrated with a specifically designed corrosion cell. The testing environment was Hanks’ solution (simulated body fluid) at 37.5oC. Electrochemical impedance spectroscopic (EIS) measurement was carried out to monitor the change of corrosion resistance at different periods during the BRF test. Experiments indicate that the laser-welded NiTi alloy would be more susceptible to the corrosion fatigue attack than the bare NiTi alloy. This finding can serve as a benchmark for the product designers and engineers to determine the factor of safety of NiTi medical devices fabricated using laser welding.

Synergy Between an Improved Covariate Unit Root Test and Cross-sectionally Dependent Panel Data Unit Root Tests, with two Applications

This paper proposes the use of an improved covariate unit root test which exploits the cross-sectional dependence information when the panel data null hypothesis of a unit root is rejected. More explicitly, to increase the power of the test, we suggest the utilization of more than one covariate and offer several ways to select the ‘best’ covariates from the set of potential covariates represented by the individuals in the panel. Employing our methods, we investigate the Prebish-Singer hypothesis for nine commodity prices. Our results show that this hypothesis holds for all but the price of petroleum.

The Effect of the Secret Ballot on Party System Fragmentation: A Test of Three Competing Arguments

Few studies have examined the impact that the adoption of the secret ballot had on party system fragmentation outside the United States. This article tests arguments maintaining that the adoption of the secret ballot had a negative, positive or nil effect on party system fragmentation. Using time-series cross-sectional data from
several countries adopting the secret ballot around the turn of the twentieth century, the results demonstrate that the adoption of the secret ballot did not hinder – though did not favour, either – the development of multiparty systems.

Conductivity sensor technology application in steady state migration test

In this paper the current development of the steady state migration test was reviewed. Experiments were carried out for a series of concrete mixes with the steady state migration test in which conductivity sensor technology is applied. With the developed steady state migration test, conductivity in anolyte, loop current and temperature can be monitored in real time. The experimental results are conductive to understand the mechanism of chloride migration during both unsteady state and steady state. The conductivity of anolyte could be used to calculate the chloride concentration in anolyte and the theoretical correlation between them was explained. Over all, the developed steady state migration is an effective, convenient, well-defined in theory and plentiful with information method which could be used to determine the chloride diffusion coefficient of cementitious materials.

Vehicle-barrier tracking of a scaled crash test for roadside barrier design

In this paper the tracking system used to perform a scaled vehicle-barrier crash test is reported. The scaled crash test was performed as part of a wider project aimed at designing a new safety barrier making use of natural building materials. The scaled crash test was designed and performed as a proof of concept of the new mass-based safety barriers and the study was composed of two parts: the scaling technique and of a series of performed scaled crash tests. The scaling method was used for 1) setting the scaled test impact velocity so that energy dissipation and momentum transferring, from the car to the barrier, can be reproduced and 2) predicting the acceleration, velocity and displacement values occurring in the full-scale impact from the results obtained in a scaled test. To achieve this goal the vehicle and barrier displacements were to be recorded together with the vehicle accelerations and angular velocities. These quantities were measured during the tests using acceleration sensors and a tracking system. The tracking system was composed of a high speed camera and a set of targets to measure the vehicle linear and angular velocities. A code was developed to extract the target velocities from the videos and the velocities obtained were then compared with those obtained integrating the accelerations provided by the sensors to check the reliability of the method.

Non-pharmacological interventions for cognitive impairment due to systemic cancer treatment

This is the protocol for a review and there is no abstract. The objectives are as follows:

The primary objective of this review is to evaluate the effects of non-pharmacological interventions among cancer patients targeted at maintaining cognitive function or ameliorating cognitive impairment as a result of cancer or receipt of systemic cancer treatment (i.e. chemotherapy or hormonal therapies in isolation or combination with other treatments). Patients who have received treatments such as cranial radiation for central nervous system tumours or metastases are not the focus of this review and will be excluded.

A second objective is to evaluate the effectiveness of non-pharmacological interventions for improving non-cognitive outcomes e.g. quality of life among this population.

Thirdly, we will extract and analyse data regarding the duration of intervention effects.

Fourthly, we will examine each study to identify safety as an outcome and incorporate information on intervention safety where possible. Evidence for the review will be based on data from randomised trials.

The performance of concrete exposed to marine environments: predictive modelling and use of laboratory/on site test methods

This paper reports an approach by which laboratory based testing and numerical modelling can be combined to predict the long term performance of a range of concretes exposed to marine environments. Firstly, a critical review of the test methods for assessing the chloride penetration resistance of concrete is given. The repeatability of the different test results is also included. In addition to the test methods, a numerical simulation model is used to explore the test data further to obtain long-term chloride ingress trends. The combined use of testing and modelling is validated with the help of long-term chloride ingress data from a North Sea exposure site. In summary, the paper outlines a methodology for determining the long term performance of concrete in marine environments.

Optical coherence tomography for the diagnosis, monitoring and guiding of treatment for neovascular age-related macular degeneration:a systematic review and economic evaluation

BACKGROUND: Age-related macular degeneration is the most common cause of sight impairment in the UK. In neovascular age-related macular degeneration (nAMD), vision worsens rapidly (over weeks) due to abnormal blood vessels developing that leak fluid and blood at the macula.

OBJECTIVES: To determine the optimal role of optical coherence tomography (OCT) in diagnosing people newly presenting with suspected nAMD and monitoring those previously diagnosed with the disease.

DATA SOURCES: Databases searched: MEDLINE (1946 to March 2013), MEDLINE In-Process & Other Non-Indexed Citations (March 2013), EMBASE (1988 to March 2013), Biosciences Information Service (1995 to March 2013), Science Citation Index (1995 to March 2013), The Cochrane Library (Issue 2 2013), Database of Abstracts of Reviews of Effects (inception to March 2013), Medion (inception to March 2013), Health Technology Assessment database (inception to March 2013).

REVIEW METHODS: Types of studies: direct/indirect studies reporting diagnostic outcomes.

INDEX TEST: time domain optical coherence tomography (TD-OCT) or spectral domain optical coherence tomography (SD-OCT).

COMPARATORS: clinical evaluation, visual acuity, Amsler grid, colour fundus photographs, infrared reflectance, red-free images/blue reflectance, fundus autofluorescence imaging, indocyanine green angiography, preferential hyperacuity perimetry, microperimetry. Reference standard: fundus fluorescein angiography (FFA). Risk of bias was assessed using quality assessment of diagnostic accuracy studies, version 2. Meta-analysis models were fitted using hierarchical summary receiver operating characteristic curves. A Markov model was developed (65-year-old cohort, nAMD prevalence 70%), with nine strategies for diagnosis and/or monitoring, and cost-utility analysis conducted. NHS and Personal Social Services perspective was adopted. Costs (2011/12 prices) and quality-adjusted life-years (QALYs) were discounted (3.5%). Deterministic and probabilistic sensitivity analyses were performed.

RESULTS: In pooled estimates of diagnostic studies (all TD-OCT), sensitivity and specificity [95% confidence interval (CI)] was 88% (46% to 98%) and 78% (64% to 88%) respectively. For monitoring, the pooled sensitivity and specificity (95% CI) was 85% (72% to 93%) and 48% (30% to 67%) respectively. The FFA for diagnosis and nurse-technician-led monitoring strategy had the lowest cost (£39,769; QALYs 10.473) and dominated all others except FFA for diagnosis and ophthalmologist-led monitoring (£44,649; QALYs 10.575; incremental cost-effectiveness ratio £47,768). The least costly strategy had a 46.4% probability of being cost-effective at £30,000 willingness-to-pay threshold.

LIMITATIONS: Very few studies provided sufficient information for inclusion in meta-analyses. Only a few studies reported other tests; for some tests no studies were identified. The modelling was hampered by a lack of data on the diagnostic accuracy of strategies involving several tests.

CONCLUSIONS: Based on a small body of evidence of variable quality, OCT had high sensitivity and moderate specificity for diagnosis, and relatively high sensitivity but low specificity for monitoring. Strategies involving OCT alone for diagnosis and/or monitoring were unlikely to be cost-effective. Further research is required on (i) the performance of SD-OCT compared with FFA, especially for monitoring but also for diagnosis; (ii) the performance of strategies involving combinations/sequences of tests, for diagnosis and monitoring; (iii) the likelihood of active and inactive nAMD becoming inactive or active respectively; and (iv) assessment of treatment-associated utility weights (e.g. decrements), through a preference-based study.

STUDY REGISTRATION: This study is registered as PROSPERO CRD42012001930.

FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Do mirrors reflect reality in agonistic encounters? A test of mutual cooperation in displays

Animals frequently engage in mutual displays that may allow or at least help decisions about the outcome of agonistic encounters with mutual benefit to the opponents. In fish these often involve lateral displays, with previous studies finding evidence of population-level lateralization with a marked preference for showing the right side and using the right eye. Because both opponents tend to show this preference a head to tail configuration is formed and is used extensively during the display phase. Here we tested the significance of these lateral displays by comparing displays to a mirror with those to a real opponent behind a transparent barrier. The frequency of displays was lower to a mirror but the individual displays were of greater duration indicating a slower pace of the interaction with a mirror. This suggests that fish respond to initiatives of real opponents but as mirror images do not initiate moves the focal fish only moves when it is ready to change position. However, lateralization was still found with mirrors, indicating that the right-side bias is a feature of the individual and not of the interaction between opponents. We discuss implications for ideas about the evolution of mutual cooperation and information exchange in contests, as well as the utility of the use of mirrors in the study of aggression in fish.

A proposed model membrane and test method for microneedle insertion studies

A commercial polymeric film (Parafilm M (R), a blend of a hydrocarbon wax and a polyolefin) was evaluated as a model membrane for microneedle (MN) insertion studies. Polymeric MN arrays were inserted into Parafilm M (R) (PF) and also into excised neonatal porcine skin. Parafilm M (R) was folded before the insertions to closely approximate thickness of the excised skin. Insertion depths were evaluated using optical coherence tomography (OCT) using either a force applied by a Texture Analyser or by a group of human volunteers. The obtained insertion depths were, in general, slightly lower, especially for higher forces, for PF than for skin. However, this difference was not a large, being less than the 10% of the needle length. Therefore, all these data indicate that this model membrane could be a good alternative to biological tissue for MN insertion studies. As an alternative method to OCT, light microscopy was used to evaluate the insertion depths of MN in the model membrane. This provided a rapid, simple method to compare different MN formulations. The use of Parafilm M (R), in conjunction with a standardised force/time profile applied by a Texture Analyser, could provide the basis for a rapid MN quality control test suitable for in-process use. It could also be used as a comparative test of insertion efficiency between candidate MN formulations. 

A research-based approach to exploring the adoption of novel UK-based concrete test methods in Chinese construction sector

As part of a UK-China science bridge project - a UK government funded initiative linking leading universities and businesses in selective partnering countries in 2009 a collaborative research programme was initiated between Queen's University and the Research Institute of High Performance Concrete (part of the Central Research Institute of Building and Construction) in Beijing.

For further details email b.magee@ulster.ac.uk

Proactive Relay Selection with Joint Impact of Hardware Impairment and Co-channel Interference

In this paper, we investigate the end-to-end performance of dual-hop proactive decode-and-forward relaying networks with Nth best relay selection in the presence of two practical deleterious effects: i) hardware impairment and ii) cochannel interference. In particular, we derive new exact and asymptotic closed-form expressions for the outage probability and average channel capacity of Nth best partial and opportunistic relay selection schemes over Rayleigh fading channels. Insightful discussions are provided. It is shown that, when the system cannot select the best relay for cooperation, the partial relay selection scheme outperforms the opportunistic method under the impact of the same co-channel interference (CCI). In addition, without CCI but under the effect of hardware impairment, it is shown that both selection strategies have the same asymptotic channel capacity. Monte Carlo simulations are presented to corroborate our analysis.

The BTA stat test:A tumor marker for the detection of upper tract transitional cell carcinoma

Objectives. To conduct a prospective evaluation to determine the utility of the BTA stat test in the detection of upper tract transitional cell carcinoma (UTTCC). Monitoring for UTTCC currently relies on invasive procedures such as upper tract imaging, ureteral washing cytology (UWC) and/or ureteroscopy, or voided urine cytology (VUC). The BTA stat test is a sensitive qualitative immunoassay that detects human complement factor H-related protein in voided urine.

Methods. A total of 81 patients participated, 27 with histopathologically confirmed UTTCC, 26 with upper tract calculi, and 28 with microscopic hematuria but no evidence of urologic disease. Voided specimens collected before surgery or treatment were tested with the BTA stat test and VUC. UWC was performed in specimens collected by a ureteral catheter.

Results. The BTA stat test was significantly more sensitive and specific than VUC or UWC. The overall sensitivity for each was 82%, 11%, and 48%; the specificity was 89%, 54%, and 33%. The positive predictive value for the BTA stat test was 79% and the negative predictive value was 91%, both the highest of the three tests.

Conclusions. The BTA stat test was superior to VUC and UWC in the detection of UTTCC. These results may support the adoption of a less aggressive follow-up policy when monitoring for UTTCC when the BTA stat result is negative. If cystoscopy is negative and the BTA stat test is positive, upper tract investigations should be expedited and, if the bladder is in place, bladder biopsies performed. (C) 2001, Elsevier Science Inc.

Python PSS/E Simulation to Test Efficacy of Proposed PMU Based WAMS and Potential WAMPAC Applications

A PSS/E 32 model of a real section of the Northern Ireland electrical grid was dynamically controlled with Python 2.5. In this manner data from a proposed wide area monitoring system was simulated. The area is of interest as it is a weakly coupled distribution grid with significant distributed generation. The data was used to create an optimization and protection metric that reflected reactive power flow, voltage profile, thermal overload and voltage excursions. Step changes in the metric were introduced upon the operation of special protection systems and voltage excursions. A wide variety of grid conditions were simulated while tap changer positions and switched capacitor banks were iterated through; with the most desirable state returning the lowest optimization and protection metric. The optimized metric was compared against the metric generated from the standard system state returned by PSS/E. Various grid scenarios were explored involving an intact network and compromised networks (line loss) under summer maximum, summer minimum and winter maximum conditions. In each instance the output from the installed distributed generation is varied between 0 MW and 80 MW (120% of installed capacity). It is shown that in grid models the triggering of special protection systems is delayed by between 1 MW and 6 MW (1.5% to 9% of capacity), with 3.5 MW being the average. The optimization and protection metric gives a quantitative value for system health and demonstrates the potential efficacy of wide area monitoring for protection and control.