Метод преобразования обычной разводки печатных плат в полигональную

Описан метод преобразования традиционной разводки печатной платы в полигональную с предварительным рассмотрением вопросов построения триангуляции Делоне, диаграммы Вороного и эквидистанты к контуру.Описаний метод дозволяє автоматизувати процес полігонального розведення друкованих плат, що потрібен при проектуванні потужних радіопередавачів, а також багатошарових друкованих плат, коли на опорному шарі є присутними декілька різних кіл живлення.The described method allows to automate the polygonal interconnection process, which is essential for powerful radio transmitters designing, and also for multi-layer printed circuit boards designing, when the reference layer includes several different circuits

Organising Support for Carers of Stroke Survivors (OSCARSS): a cluster randomised controlled trial with economic evaluation.

OBJECTIVE: Investigated clinical effectiveness and cost-effectiveness of a person-centred intervention for informal carers/caregivers of stroke survivors. DESIGN: Pragmatic cluster randomised controlled trial (cRCT) with economic and process evaluation. SETTING: Clusters were services, from a UK voluntary sector specialist provider, delivering support primarily in the homes of stroke survivors and informal carers. PARTICIPANTS: Adult carers in participating clusters were referred to the study by cluster staff following initial support contact. INTERVENTIONS: Intervention was the Carer Support Needs Assessment Tool for Stroke: a staff-facilitated, carer-led approach to help identify, prioritise and address the specific support needs of carers. It required at least one face-to-face support contact dedicated to carers, with reviews as required. Control was usual care, which included carer support (unstructured and variable). OUTCOME MEASURES: Participants provided study entry and self-reported outcome data by postal questionnaires, 3 and 6 months after first contact by cluster staff. PRIMARY OUTCOME: 3-month caregiver strain (Family Appraisal of Caregiving Questionnaire, FACQ). SECONDARY OUTCOMES: FACQ subscales of caregiver distress and positive appraisals of caregiving, mood (Hospital Anxiety and Depression Scale) and satisfaction with stroke services (Pound). The economic evaluation included self-reported healthcare utilisation, intervention costs and EQ-5D-5L. RANDOMISATION AND MASKING: Clusters were recruited before randomisation to intervention or control, with stratification for size of service. Cluster staff could not be masked as training was required for participation. Carer research participants provided self-reported outcome data unaware of allocation; they consented to follow-up data collection only. RESULTS: Between 1 February 2017 and 31 July 2018, 35 randomised clusters (18 intervention; 17 control) recruited 414 cRCT carers (208 intervention; 206 control). Study entry characteristics were well balanced. PRIMARY OUTCOME MEASURE: intention-to-treat analysis for 84% retained participants (175 intervention; 174 control) found mean (SD) FACQ carer strain at 3 months to be 3.11 (0.87) in the control group compared with 3.03 (0.90) in the intervention group, adjusted mean difference of -0.04 (95% CI -0.20 to 0.13). Secondary outcomes had similarly small differences and tight CIs. Sensitivity analyses suggested robust findings. Intervention fidelity was not achieved. Intervention-related group costs were marginally higher with no additional health benefit observed on EQ-5D-5L. No adverse events were related to the intervention. CONCLUSIONS: The intervention was not fully implemented in this pragmatic trial. As delivered, it conferred no clinical benefits and is unlikely to be cost-effective compared with usual care from a stroke specialist provider organisation. It remains unclear how best to support carers of stroke survivors. To overcome the implementation challenges of person-centred care in carers' research and service development, staff training and organisational support would need to be enhanced. TRIAL REGISTRATION NUMBER: ISRCTN58414120

Organising Support for Carers of Stroke Survivors (OSCARSS): a cluster randomised controlled trial with economic evaluation

Objective: Investigated clinical effectiveness and cost-effectiveness of a person-centred intervention for informal carers/caregivers of stroke survivors. Design: Pragmatic cluster randomised controlled trial (cRCT) with economic and process evaluation. Setting: Clusters were services, from a UK voluntary sector specialist provider, delivering support primarily in the homes of stroke survivors and informal carers. Participants: Adult carers in participating clusters were referred to the study by cluster staff following initial support contact. Interventions: Intervention was the Carer Support Needs Assessment Tool for Stroke: a staff-facilitated, carer-led approach to help identify, prioritise and address the specific support needs of carers. It required at least one face-to-face support contact dedicated to carers, with reviews as required. Control was usual care, which included carer support (unstructured and variable). Outcome measures: Participants provided study entry and self-reported outcome data by postal questionnaires, 3 and 6 months after first contact by cluster staff. Primary outcome: 3-month caregiver strain (Family Appraisal of Caregiving Questionnaire, FACQ). Secondary outcomes: FACQ subscales of caregiver distress and positive appraisals of caregiving, mood (Hospital Anxiety and Depression Scale) and satisfaction with stroke services (Pound). The economic evaluation included self-reported healthcare utilisation, intervention costs and EQ-5D-5L. Randomisation and masking: Clusters were recruited before randomisation to intervention or control, with stratification for size of service. Cluster staff could not be masked as training was required for participation. Carer research participants provided self-reported outcome data unaware of allocation; they consented to follow-up data collection only. Results: Between 1 February 2017 and 31 July 2018, 35 randomised clusters (18 intervention; 17 control) recruited 414 cRCT carers (208 intervention; 206 control). Study entry characteristics were well balanced. Primary outcome measure: intention-to-treat analysis for 84% retained participants (175 intervention; 174 control) found mean (SD) FACQ carer strain at 3 months to be 3.11 (0.87) in the control group compared with 3.03 (0.90) in the intervention group, adjusted mean difference of −0.04 (95% CI −0.20 to 0.13). Secondary outcomes had similarly small differences and tight CIs. Sensitivity analyses suggested robust findings. Intervention fidelity was not achieved. Intervention-related group costs were marginally higher with no additional health benefit observed on EQ-5D-5L. No adverse events were related to the intervention. Conclusions: The intervention was not fully implemented in this pragmatic trial. As delivered, it conferred no clinical benefits and is unlikely to be cost-effective compared with usual care from a stroke specialist provider organisation. It remains unclear how best to support carers of stroke survivors. To overcome the implementation challenges of person-centred care in carers’ research and service development, staff training and organisational support would need to be enhanced. Trial registration number: ISRCTN58414120

Personal exposure to static and time-varying magnetic fields during MRI procedures in clinical practice in the UK

Background: MRI has developed into one of the most important medical diagnostic imaging modalities, but it exposes staff to static magnetic fields (SMF) when present in the vicinity of the MR system, and to radiofrequency and switched gradient electromagnetic fields if they are present during image acquisition. We measured exposure to SMF and motion-induced time-varying magnetic fields (TVMF) in MRI staff in clinical practice in the UK to enable extensive assessment of personal exposure levels and variability, which enables comparison to other countries. Methods: 8 MRI facilities across National Health Service sites in England, Wales and Scotland were included, and staff randomly selected during the days when measurements were performed were invited to wear a personal MRI-compatible dosimeter and keep a diary to record all procedures and tasks performed during the measured shift. Results: 98 participants, primarily radiographers (71%) but also other healthcare staff, anaesthetists and other medical staff were included, resulting in 149 measurements. Average geometric mean peak SMF and TVMF exposures were 448 mT (range 20–2891) and 1083 mT/s (9–12 355 mT/s), and were highest for radiographers (GM=559 mT and GM=734 mT/s). Time-weighted exposures to SMF and TVMF (GM=16 mT (range 5–64) and GM=14 mT/s (range 9–105)) and exposed-time-weighted exposures to SMF and TVMF (GM=27 mT (range 11–89) and GM=17 mT/s (range 9–124)) were overall relative low—primarily because staff were not in the MRI suite for most of their shifts—and did not differ significantly between occupations. Conclusions: These results are comparable to the few data available from the UK but they differ from recent data collected in the Netherlands, indicating that UK staff are exposed for shorter periods but to higher levels. These data indicate that exposure to SMF and TVMF from MRI scanners cannot be extrapolated across countries

Optimal designs for cost-efficient assessment of exposure subject to measurement error

In epidemiological studies of an exposure-response association, often only a mismeasured exposure is taken on each individual of the population under study. If ignored, exposure measurement error can bias the estimated exposure-response association in question. A reliability study may be carried out to estimate the relation between the mismeasured and true exposure, which could then be used to adjust for measurement error in the attenuated exposure-response relationship. However, taking repeated exposure measurements may be expensive. Given a fixed total study cost, a two-stage design may be a more efficient approach for regression parameter estimation compared to the traditional single-stage design since, in the second-stage, repeated measurement is restricted to a sample of first-stage subjects. Sampling the extremes of the first-stage exposure distribution has been shown to be more efficient than random sampling.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Instrumental Variables vs. Grouping Approach for Reducing Bias Due to Measurement Error

Attenuation of the exposure-response relationship due to exposure measurement error is often encountered in epidemiology. Given that error cannot be totally eliminated, bias correction methods of analysis are needed. Many methods require more than one exposure measurement per person to be made, but the `group mean OLS method,' in which subjects are grouped into several a priori defined groups followed by ordinary least squares (OLS) regression on the group means, can be applied with one measurement. An alternative approach is to use an instrumental variable (IV) method in which both the single error-prone measure and an IV are used in IV analysis. In this paper we show that the `group mean OLS' estimator is equal to an IV estimator with the group mean used as IV, but that the variance estimators for the two methods are different. We derive a simple expression for the bias in the common estimator which is a simple function of group size, reliability and contrast of exposure between groups, and show that the bias can be very small when group size is large. We compare this method with a new proposal (group mean ranking method), also applicable with a single exposure measurement, in which the IV is the rank of the group means. When there are two independent exposure measurements per subject, we propose a new IV method (EVROS IV) and compare it with Carroll and Stefanski's (CS IV) proposal in which the second measure is used as an IV; the new IV estimator combines aspects of the `group mean' and `CS' strategies. All methods are evaluated in terms of bias, precision and root mean square error via simulations and a dataset from occupational epidemiology. The `group mean ranking method' does not offer much improvement over the `group mean method.' Compared with the `CS' method, the `EVROS' method is less affected by low reliability of exposure. We conclude that the group IV methods we propose may provide a useful way to handle mismeasured exposures in epidemiology with or without replicate measurements. Our finding may also have implications for the use of aggregate variables in epidemiology to control for unmeasured confounding.

Sample size and power calculations for trials and quasi-experimental studies with clustering

This article considers the estimation of power and sample size in experimental and quasi-experimental intervention studies, where there is clustering of subjects within one or both intervention arms, for both continuous and binary outcomes. A new command, clsampsi, which has a wide range of options, calculates the power and sample size needed (that is, the number of clusters and cluster size) by using the noncentral F distribution as described by Moser, Stevens, and Watts (1989, Communications in Statistics—Theory and Methods 18: 3963–3975). For comparative purposes, this command can also produce power and sample-size estimates on the basis of existing methods that use a normal approximation

Design and analysis of trials with a partially nested design and a binary outcome measure.

Where treatments are administered to groups of patients or delivered by therapists, outcomes for patients in the same group or treated by the same therapist may be more similar, leading to clustering. Trials of such treatments should take account of this effect. Where such a treatment is compared with an un‐clustered treatment, the trial has a partially nested design. This paper compares statistical methods for this design where the outcome is binary. Investigation of consistency reveals that a random coefficient model with a random effect for group or therapist is not consistent with other methods for a null treatment effect, and so this model is not recommended for this design. Small sample performance of a cluster‐adjusted test of proportions, a summary measures test and logistic generalised estimating equations and random intercept models are investigated through simulation. The expected treatment effect is biased for the logistic models. Empirical test size of two‐sided tests is raised only slightly, but there are substantial biases for one‐sided tests. Three formulae are proposed for calculating sample size and power based on (i) the difference of proportions, (ii) the log‐odds ratio or (iii) the arc‐sine transformation of proportions. Calculated power from these formulae is compared with empirical power from a simulations study. Logistic models appeared to perform better than those based on proportions with the likelihood ratio test performing best in the range of scenarios considered. For these analyses, the log‐odds ratio method of calculation of power gave an approximate lower limit for empirical power. © 2015 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd