Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500

Purpose: A clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500 (Japan) was performed to evaluate validity and repeatability compared with non-cycloplegic subjective refraction and Javal–Schiotz keratometry. An investigation into the dynamic recording capabilities of the instrument was also conducted. Methods: Refractive error measurements were obtained from 150 eyes of 75 subjects (aged 25.12 ± 9.03 years), subjectively by a masked optometrist, and objectively with the WAM-5500 at a second session. Keratometry measurements from the WAM-5500 were compared to Javal–Schiotz readings. Intratest variability was examined on all subjects, whilst intertest variability was assessed on a subgroup of 44 eyes 7–14 days after the initial objective measures. The accuracy of the dynamic recording mode of the instrument and its tolerance to longitudinal movement was evaluated using a model eye. An additional evaluation of the dynamic mode was performed using a human eye in relaxed and accommodated states. Results: Refractive error determined by the WAM-5500 was found to be very similar (p = 0.77) to subjective refraction (difference, -0.01 ± 0.38 D). The instrument was accurate and reliable over a wide range of refractive errors (-6.38 to +4.88 D). WAM-5500 keratometry values were steeper by approximately 0.05 mm in both the vertical and horizontal meridians. High intertest repeatability was demonstrated for all parameters measured: for sphere, cylinder power and MSE, over 90% of retest values fell within ±0.50 D of initial testing. In dynamic (high-speed) mode, the root-mean-square of the fluctuations was 0.005 ± 0.0005 D and a high level of recording accuracy was maintained when the measurement ring was significantly blurred by longitudinal movement of the instrument head. Conclusion: The WAM-5500 Auto Ref/Keratometer represents a reliable and valid objective refraction tool for general optometric practice, with important additional features allowing pupil size determination and easy conversion into high-speed mode, increasing its usefulness post-surgically following accommodating intra-ocular lens implantation, and as a research tool in the study of accommodation.

An evaluation of task analysis techniques for industrial process control

The concept of a task is fundamental to the discipline of ergonomics. Approaches to the analysis of tasks began in the early 1900's. These approaches have evolved and developed to the present day, when there is a vast array of methods available. Some of these methods are specific to particular contexts or applications, others more general. However, whilst many of these analyses allow tasks to be examined in detail, they do not act as tools to aid the design process or the designer. The present thesis examines the use of task analysis in a process control context, and in particular the use of task analysis to specify operator information and display requirements in such systems. The first part of the thesis examines the theoretical aspect of task analysis and presents a review of the methods, issues and concepts relating to task analysis. A review of over 80 methods of task analysis was carried out to form a basis for the development of a task analysis method to specify operator information requirements in industrial process control contexts. Of the methods reviewed Hierarchical Task Analysis was selected to provide such a basis and developed to meet the criteria outlined for such a method of task analysis. The second section outlines the practical application and evolution of the developed task analysis method. Four case studies were used to examine the method in an empirical context. The case studies represent a range of plant contexts and types, both complex and more simple, batch and continuous and high risk and low risk processes. The theoretical and empirical issues are drawn together and a method developed to provide a task analysis technique to specify operator information requirements and to provide the first stages of a tool to aid the design of VDU displays for process control.

Spatial tuning studies of the pattern evoked electroretinogram

The locus of origin of the pattern evoked electroretinogram, (PERG), has been the subject of considerable discussion. A novel approach was adopted in this study to further elaborate the nature of the PERG evoked by pattern onset/offset presentation. The PERG was found to be linearly related to stimulus contrast and in particular was linearly related to the temporal contrast of the retinal image, when elicited by patterns of low spatial frequency. At high spatial frequencies the retinal image contrast is significantly reduced because of optical degradation. This is described by the eye's modulation transfer function (MTF). The retinal contrast of square wave grating and chequerboard patterns of increasing spatial frequency were found by filtering their Fourier transforms by the MTF. The filtered pattern harmonics were then resynthesised to constitute a profile of retinal image illuminance from which the temporal and spatial contrast of the image could be calculated. If the PERG is a pure illuminance response it should be spatially insensitive and dependent upon the temporal contrast of stimulation. The calculated loss of temporal contrast for finer patterns was expressed as a space-averaged temporal contrast attentuation factor. This factor, applied to PERGs evoked by low spatial frequency patterns, was used to predict the retinal illuminance response elicited by a finer pattern. The predicted response was subtracted from the recorded signal and residual waveform was proposed to represent specific activity. An additional correction for the attenuation of spatial contrast was applied to the extracted pattern specific response. Pattern specific responses computed for different spatial frequency patterns in this way are the predicted result of iso-contrast pattern stimulation. The pattern specific responses demonstrate a striking bandpass spatial selectivity which peaks at higher spatial frequencies in the more central retina. The variation of spatial sensitivity with eccentricity corresponds closely with estimated ganglion receptive field centre separation and psychophysical data. The variation of retinal structure with eccentricity, in the form of the volumes of the nuclear layers, was compared with the amplitudes of the computed retinal illuminance and pattern specific responses. The retinal illuminance response corresponds more closely to the outer and inner nuclear layers whilst the pattern specific response appears more closely related to the ganglion cell layer. In general the negative response transients correspond to the more proximal retinal layers. This thesis therefore supports the proposed contribution of proximal retinal cell activity to the PERG and describes techniques which may be further elaborated for more detailed studies of retinal receptive field dimensions.

Evaluation of the auto-refraction function of the Nidek OPD-Scan III

Background: The aim was to evaluate the validity and repeatability of the auto-refraction function of the Nidek OPD-Scan III (Nidek Technologies, Gamagori, Japan) compared with non-cycloplegic subjective refraction. The Nidek OPD-Scan III is a new aberrometer/corneal topographer workstation based on the skiascopy principle. It combines a wavefront aberrometer, topographer, autorefractor, auto keratometer and pupillometer/pupillographer. Methods: Objective refraction results obtained using the Nidek OPD-Scan III were compared with non-cycloplegic subjective refraction for 108 eyes of 54 participants (29 female) with a mean age of 23.7±9.5 years. Intra-session and inter-session variability were assessed on 14 subjects (28 eyes). Results: The Nidek OPD-Scan III gave slightly more negative readings than results obtained by subjective refraction (Nidek mean difference -0.19±0.36 DS, p<0.01 for sphere; -0.19±0.35 DS, p<0.01 for mean spherical equivalent; -0.002±0.23 DC, p=0.91 for cylinder; -0.06±0.38 DC, p=0.30 for J0 and -0.36±0.31 DC for J45, p=0.29). Auto-refractor results for 74 per cent of spherical readings and 60 per cent of cylindrical powers were within±0.25 of subjective refraction. There was high intra-session and inter-session repeatability for all parameters; 90 per cent of inter-session repeatability results were within 0.25 D. Conclusion: The Nidek OPD-Scan III gives valid and repeatable measures of objective refraction when compared with non-cycloplegic subjective refraction. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

Design and evaluation of a framework for cooperative and adaptive QoS control of DSRC network for road safety applications

Dedicated short-range communications (DSRC) are a promising vehicle communication technique for collaborative road safety applications (CSA). However, road safety applications require highly reliable and timely wireless communications, which present big challenges to DSRC based vehicle networks on effective and robust quality of services (QoS) provisioning due to the random channel access method applied in the DSRC technique. In this paper we examine the QoS control problem for CSA in the DSRC based vehicle networks and presented an overview of the research work towards the QoS control problem. After an analysis of the system application requirements and the DSRC vehicle network features, we propose a framework for cooperative and adaptive QoS control, which is believed to be a key for the success of DSRC on supporting effective collaborative road safety applications. A core design in the proposed QoS control framework is that network feedback and cross-layer design are employed to collaboratively achieve targeted QoS. A design example of cooperative and adaptive rate control scheme is implemented and evaluated, with objective of illustrating the key ideas in the framework. Simulation results demonstrate the effectiveness of proposed rate control schemes in providing highly available and reliable channel for emergency safety messages. © 2013 Wenyang Guan et al.

Antecedents and consequences of service quality in consumer evaluation of self-service internet technologies

Advances in technology coupled with increasing labour costs have caused service firms to explore self-service delivery options. Although some studies have focused on self-service and use of technology in service delivery, few have explored the role of service quality in consumer evaluation of technology-based self-service options. By integrating and extending the self-service quality framework the service evaluation model and the Technology Acceptance Model the authors address this emerging issue by empirically testing a comprehensive model that captures the antecedents and consequences of perceived service quality to predict continued customer interaction in the technology-based self-service context of Internet banking. Important service evaluation constructs like perceived risk, perceived value and perceived satisfaction are modelled in this framework. The results show that perceived control has the strongest influence on service quality evaluations. Perceived speed of delivery, reliability and enjoyment also have a significant impact on service quality perceptions. The study also found that even though perceived service quality, perceived risk and satisfaction are important predictors of continued interaction, perceived customer value plays a pivotal role in influencing continued interaction.

An evaluation of quinolone prescribing in a group of acute hospitals:Development of an objective measure of usage

Objectives: To develop an objective measure to enable hospital Trusts to compare their use of antibiotics. Design: Self-completion, postal questionnaire with telephone follow up. Sample: 4 hospital trusts in the English Midlands. Results: The survey showed that it was possible to collect data concerning the number of Defined Daily Doses (DDD's) of quinolone antibiotic dispensed per Finished Consultant Episode (FCE) in each Trust.. In the 4 trusts studied the mean DDD/FCE was 0.197 (range 0.117 to 0.258). This indicates that based on a typical course length of 5 days, 3.9% of patient episodes resulted in the prescription of a quinolone antibiotic. Antibiotic prescribing control measures in each Trust were found to be comparable. Conclusion: The measure will enable Trusts to objectively compare their usage of quinolone antibiotics and use this information to carry out clinical audit should differences be recorded. This is likely to be applicable to other groups of antibiotics.

The Evaluation of health and safety auditing systems

The specific objective of the research was to evaluate proprietary audit systems. Proprietary audit systems comprise question sets containing approximately 500 questions dealing with selected aspects of health and safety management. Each question is allotted a number of points and an organisation seeks to judge its health and safety performance by the overall score achieved in the audit. Initially it was considered that the evaluation method might involve comparing the proprietary audit scores with other methods of measuring safety performance. However, what appeared to be missing in the first instance was information that organisations could use to compare the contrast question set content against their own needs. A technique was developed using the computer database FileMaker Pro. This enables questions in an audit to be sorted into categories using a process of searching for key words. Questions that are not categorised by word searching can be identified and sorted manually. The process can be completed in 2-3 hours which is considerably faster than manual categorisation of questions which typically takes about 10 days. The technique was used to compare and contrast three proprietary audits: ISRS, CHASE and QSA. Differences and similarities between these audits were successfully identified. It was concluded that in general proprietary audits need to focus to a greater extent on identifying strengths and weaknesses in occupational health and safety management systems. To do this requires the inclusion of more probing questions which consider whether risk control measures are likely to be successful.

An evaluation of TCP over wired-to-wireless networks

To exploit the popularity of TCP as still the dominant sender and protocol of choice for transporting data reliably across the heterogeneous Internet, this thesis explores end-to-end performance issues and behaviours of TCP senders when transferring data to wireless end-users. The theme throughout is on end-users located specifically within 802.11 WLANs at the edges of the Internet, a largely untapped area of work. To exploit the interests of researchers wanting to study the performance of TCP accurately over heterogeneous conditions, this thesis proposes a flexible wired-to-wireless experimental testbed that better reflects conditions in the real-world. To exploit the transparent functionalities between TCP in the wired domain and the IEEE 802.11 WLAN protocols, this thesis proposes a more accurate methodology for gauging the transmission and error characteristics of real-world 802.11 WLANs. It also aims to correlate any findings with the functionality of fixed TCP senders. To exploit the popularity of Linux as a popular operating system for many of the Internet’s data servers, this thesis studies and evaluates various sender-side TCP congestion control implementations within the recent Linux v2.6. A selection of the implementations are put under systematic testing using real-world wired-to-wireless conditions in order to screen and present a viable candidate/s for further development and usage in the modern-day heterogeneous Internet. Overall, this thesis comprises a set of systematic evaluations of TCP senders over 802.11 WLANs, incorporating measurements in the form of simulations, emulations, and through the use of a real-world-like experimental testbed. The goal of the work is to ensure that all aspects concerned are comprehensively investigated in order to establish rules that can help to decide under which circumstances the deployment of TCP is optimal i.e. a set of paradigms for advancing the state-of-the-art in data transport across the Internet.

Preliminary in vitro toxicological evaluation of a series of 2-pyridylcarboxamidrazone candidate anti-tuberculosis compounds III

We have evaluated the cytotoxicity of a series of novel anti-tubercular 2-pyridyl carboxamidrazones through incubation with human mononuclear leucocytes (MNL), with and without a rat microsomal metabolising system. Isoniazid (INH), the closest structurally related agent, was used as a positive control. Incubation of the 3-benzyloxy-benzylidene, dimethylpropyl-benzylidene and 4-phenyl-benzylidene with MNL showed no significant toxicity in comparison with either INH or DMSO vehicle control. However, the 4-N,N-dimethylamino-1-naphthylidene derivative exerted more than sevenfold greater toxicity compared with INH, while the 4-N,N-dimethylamino-1-naphthylidene, 2-benzyloxy-3-methoxy-benzylidene, 2-t-butylthio-benzylidene and 4-i-propyl-benzylidene derivatives showed toxicity which ranged from five to fourfold that of INH. In the presence of either rat microsomes with or without NADPH, the 3-benzyloxy-benzylidene, dimethylpropyl-benzylidene and 4-phenyl-benzylidene derivatives showed no metabolically-mediated cytotoxicity. The latter two derivatives showed a combination of low toxicity and considerable efficacy against Mycobacteria tuberculosis in vitro and show promise for future development. © 2001 Elsevier Science B.V.

Multiple component patient safety intervention in English hospitals:controlled evaluation of second phase

Objective: To independently evaluate the impact of the second phase of the Health Foundation's Safer Patients Initiative (SPI2) on a range of patient safety measures. Design: A controlled before and after design. Five substudies: survey of staff attitudes; review of case notes from high risk (respiratory) patients in medical wards; review of case notes from surgical patients; indirect evaluation of hand hygiene by measuring hospital use of handwashing materials; measurement of outcomes (adverse events, mortality among high risk patients admitted to medical wards, patients' satisfaction, mortality in intensive care, rates of hospital acquired infection). Setting: NHS hospitals in England. Participants: Nine hospitals participating in SPI2 and nine matched control hospitals. Intervention The SPI2 intervention was similar to the SPI1, with somewhat modified goals, a slightly longer intervention period, and a smaller budget per hospital. Results: One of the scores (organisational climate) showed a significant (P=0.009) difference in rate of change over time, which favoured the control hospitals, though the difference was only 0.07 points on a five point scale. Results of the explicit case note reviews of high risk medical patients showed that certain practices improved over time in both control and SPI2 hospitals (and none deteriorated), but there were no significant differences between control and SPI2 hospitals. Monitoring of vital signs improved across control and SPI2 sites. This temporal effect was significant for monitoring the respiratory rate at both the six hour (adjusted odds ratio 2.1, 99% confidence interval 1.0 to 4.3; P=0.010) and 12 hour (2.4, 1.1 to 5.0; P=0.002) periods after admission. There was no significant effect of SPI for any of the measures of vital signs. Use of a recommended system for scoring the severity of pneumonia improved from 1.9% (1/52) to 21.4% (12/56) of control and from 2.0% (1/50) to 41.7% (25/60) of SPI2 patients. This temporal change was significant (7.3, 1.4 to 37.7; P=0.002), but the difference in difference was not significant (2.1, 0.4 to 11.1; P=0.236). There were no notable or significant changes in the pattern of prescribing errors, either over time or between control and SPI2 hospitals. Two items of medical history taking (exercise tolerance and occupation) showed significant improvement over time, across both control and SPI2 hospitals, but no additional SPI2 effect. The holistic review showed no significant changes in error rates either over time or between control and SPI2 hospitals. The explicit case note review of perioperative care showed that adherence rates for two of the four perioperative standards targeted by SPI2 were already good at baseline, exceeding 94% for antibiotic prophylaxis and 98% for deep vein thrombosis prophylaxis. Intraoperative monitoring of temperature improved over time in both groups, but this was not significant (1.8, 0.4 to 7.6; P=0.279), and there were no additional effects of SPI2. A dramatic rise in consumption of soap and alcohol hand rub was similar in control and SPI2 hospitals (P=0.760 and P=0.889, respectively), as was the corresponding decrease in rates of Clostridium difficile and meticillin resistant Staphylococcus aureus infection (P=0.652 and P=0.693, respectively). Mortality rates of medical patients included in the case note reviews in control hospitals increased from 17.3% (42/243) to 21.4% (24/112), while in SPI2 hospitals they fell from 10.3% (24/233) to 6.1% (7/114) (P=0.043). Fewer than 8% of deaths were classed as avoidable; changes in proportions could not explain the divergence of overall death rates between control and SPI2 hospitals. There was no significant difference in the rate of change in mortality in intensive care. Patients' satisfaction improved in both control and SPI2 hospitals on all dimensions, but again there were no significant changes between the two groups of hospitals. Conclusions: Many aspects of care are already good or improving across the NHS in England, suggesting considerable improvements in quality across the board. These improvements are probably due to contemporaneous policy activities relating to patient safety, including those with features similar to the SPI, and the emergence of professional consensus on some clinical processes. This phenomenon might have attenuated the incremental effect of the SPI, making it difficult to detect. Alternatively, the full impact of the SPI might be observable only in the longer term. The conclusion of this study could have been different if concurrent controls had not been used.

Decreased efficiency of trypsinization of cells following photodynamic therapy:evaluation of a role for tissue transglutaminase

Identifying the cellular responses to photodynamic therapy (PDT) is important if the mechanisms of cellular damage are to be fully understood. The relationship between sensitizer, fluence rate and the removal of cells by trypsinization was studied using the RIF-1 cell line. Following treatment of RIF-1 cells with pyridinium zinc (II) phthalocyanine (PPC), or polyhaematoporphyrin at 10 mW cm−2 (3 J cm−2), there was a significant number of cells that were not removed by trypsin incubation compared to controls. Decreasing the fluence rate from 10 to 2.5 mW cm−2 resulted in a two-fold increase in the number of cells attached to the substratum when PPC used as sensitizer; however, with 5,10,15,20 meso-tetra(hydroxyphenyl) chlorin (m-THPC) there was no resistance to trypsinization following treatment at either fluence rate. The results indicate that resistance of cells to trypsinization following PDT is likely to be both sensitizer and fluence rate dependent. Increased activity of the enzyme tissue-transglutaminase (tTGase) was observed following PPC-PDT, but not following m-THPC-PDT. Similar results were obtained using HT29 human colonic carcinoma and ECV304 human umbilical vein endothelial cell lines. Hamster fibrosarcoma cell (Met B) clones transfected with human tTGase also exhibited resistance to trypsinization following PPC-mediated photosensitization; however, a similar degree of resistance was observed in PDT-treated control Met B cells suggesting that tTGase activity alone was not involved in this process.