225 research outputs found

    Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices

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    This paper describes a method for prefabricating screw, pneumatic, and solenoid valves and embedding them in microfluidic devices. This method of prefabrication and embedding is simple, requires no advanced fabrication, and is compatible with soft lithography. Because prefabrication allows many identical valves to be made at one time, the performance across different valves made in the same manner is reproducible. In addition, the performance of a single valve is reproducible over many cycles of opening and closing: an embedded solenoid valve opened and closed a microfluidic channel more than 100,000 times with no apparent deterioration in its function. It was possible to combine all three types of prefabricated valves in a single microfluidic device to control chemical gradients in a microfluidic channel temporally and spatially

    Investigating digital video applications in distance learning

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    The paper gives a brief overview of the use of digital video in distance education, the background to The Open University's Digital Video Applications (DiVA) Project, the contexts in which the Digital Video Library system is being used and some evaluation findings. Through DiVA, the university is investigating how it can use its video assets effectively, to support reuse of existing materials in course production. The project team is also evaluating student use of the system. The paper reports on an observation study which revealed several usability issues and stakeholders' opinions about potential uses of the DiVA system. This is followed by findings from an evaluation of student use of the system at a residential school and its use as part of an online learning activity undertaken by students accessing the system remotely. Evaluation findings to date indicate some quality and workload issues but they also show opportunities that come to light when using the DiVA system

    Classifying Alternative Approaches for Simple Drug Possession: A Two-Level Taxonomy

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    Background: Increasing international attention is being given to alternative measures to criminalization for the possession of illicit drug. Such schemes are heterogeneous and a clear conceptual framework for their discussion and analysis is lacking. Aim: To present a conceptually informed, empirically based taxonomy for the classification of alternative measures to decriminalization for the possession of drugs. Methods: The research uses qualitative comparative analysis (QCA) of existing alternative measures. It proceeds from analysis of existing distinctions between and classifications of alternative measures. It uses data from a realist review of alternative measures in nine countries (Australia, Czech Republic, Denmark, Germany, Jamaica, Netherland, Portugal, UK and USA) to derive three dimensions of comparison (whether they: are de jure or de facto; involve diversion to an educative, therapeutic of social service; involve the use of civil/administrative sanctions). A QCA truth table using data from twenty-six schemes in the nine countries is used to identify types in the taxonomy. The types are grouped - using pragmatic reduction informed by Boolean minimization across a smaller number of classes in order to create a two-level taxonomy. Results: The resulting taxonomy contains six types of alternative measures: depenalization; de facto diversion; de jure diversion; decriminalization with diversion and civil sanctions, decriminalization with civil sanctions; and decriminalization with no sanctions. The six types fall into three classes: depenalization; diversion; and decriminalization. It is possible to classify emerging alternatives into this new taxonomy. Conclusion: Conceptually informed empirical observation of cases enables the construction of a two-level taxonomy of alternative measures to criminalization for the simple possession of drugs. This may facilitate clearer and better-informed discussion of alternatives to criminalization for drug possession

    Lifespan-on-a-chip: microfluidic chambers for performing lifelong observation of C. elegans

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    This article describes the fabrication of a microfluidic device for the liquid culture of many individual nematode worms (Caenorhabditis elegans) in separate chambers. Each chamber houses a single worm from the fourth larval stage until death, and enables examination of a population of individual worms for their entire adult lifespans. Adjacent to the chambers, the device includes microfluidic worm clamps, which enable periodic, temporary immobilization of each worm. The device made it possible to track changes in body size and locomotion in individual worms throughout their lifespans. This ability to perform longitudinal measurements within the device enabled the identification of age-related phenotypic changes that correlate with lifespan in C. elegans

    Comparing alternating pressure mattresses and high-specification foam mattresses to prevent pressure ulcers in high-risk patients: the PRESSURE 2 RCT

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    Background: Pressure ulcers (PUs) are a burden to patients, carers and health-care providers. Specialist mattresses minimise the intensity and duration of pressure on vulnerable skin sites in at-risk patients. Primary objective: Time to developing a new PU of category ≥ 2 in patients using an alternating pressure mattress (APM) compared with a high-specification foam mattress (HSFM). Design: A multicentre, Phase III, open, prospective, planned as an adaptive double-triangular group sequential, parallel-group, randomised controlled trial with an a priori sample size of 2954 participants. Randomisation used minimisation (incorporating a random element). Setting: The trial was set in 42 secondary and community inpatient facilities in the UK. Participants: Adult inpatients with evidence of acute illness and at a high risk of PU development. Interventions and follow-up: APM or HSFM – the treatment phase lasted a maximum of 60 days; the final 30 days were post-treatment follow-up. Main outcome measures: Time to event. Results: From August 2013 to November 2016, 2029 participants were randomised to receive either APM (n = 1016) or HSFM (n = 1013). Primary end point – 30-day final follow-up: of the 2029 participants in the intention-to-treat population, 160 (7.9%) developed a new PU of category ≥ 2. There was insufficient evidence of a difference between groups for time to new PU of category ≥ 2 [Fine and Gray model HR 0.76, 95% confidence interval (CI) 0.56 to 1.04; exact p-value of 0.0890 and 2% absolute difference]. Treatment phase sensitivity analysis: 132 (6.5%) participants developed a new PU of category ≥ 2 between randomisation and end of treatment phase. There was a statistically significant difference in the treatment phase time-to-event sensitivity analysis (Fine and Gray model HR 0.66, 95% CI 0.46 to 0.93; p = 0.0176 and 2.6% absolute difference). Secondary end points – 30-day final follow-up: new PUs of category ≥ 1 developed in 350 (17.2%) participants, with no evidence of a difference between mattress groups in time to PU development, (Fine and Gray model HR 0.83, 95% CI 0.67 to 1.02; p-value = 0.0733 and absolute difference 3.1%). New PUs of category ≥ 3 developed in 32 (1.6%) participants with insufficient evidence of a difference between mattress groups in time to PU development (Fine and Gray model HR 0.81, 95% CI 0.40 to 1.62; p = 0.5530 and absolute difference 0.4%). Of the 145 pre-existing PUs of category 2, 89 (61.4%) healed – there was insufficient evidence of a difference in time to healing (Fine and Gray model HR 1.12, 95% CI 0.74 to 1.68; p = 0.6122 and absolute difference 2.9%). Health economics – the within-trial and long-term analysis showed APM to be cost-effective compared with HSFM; however, the difference in costs models are small and the quality-adjusted life-year gains are very small. There were no safety concerns. Blinded photography substudy – the reliability of central blinded review compared with clinical assessment for PUs of category ≥ 2 was ‘very good’ (kappa statistic 0.82, prevalence- and bias-adjusted kappa 0.82). Quality-of-life substudy – the Pressure Ulcer Quality of Life – Prevention (PU-QoL-P) instrument meets the established criteria for reliability, construct validity and responsiveness. Limitations: A lower than anticipated event rate. Conclusions: In acutely ill inpatients who are bedfast/chairfast and/or have a category 1 PU and/or localised skin pain, APMs confer a small treatment phase benefit that is diminished over time. Overall, the APM patient compliance, very low PU incidence rate observed and small differences between mattresses indicate the need for improved indicators for targeting of APMs and individualised decision-making. Decisions should take into account skin status, patient preferences (movement ability and rehabilitation needs) and the presence of factors that may be potentially modifiable through APM allocation, including being completely immobile, having nutritional deficits, lacking capacity and/or having altered skin/category 1 PU. Future work: Explore the relationship between mental capacity, levels of independent movement, repositioning and PU development. Explore ‘what works for whom and in what circumstances’. Trial registration: Current Controlled Trials ISRCTN01151335. Funding: This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 52. See the NIHR Journals Library website for further project information
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