424 research outputs found
Effects of arcing due to spacecraft charging on spacecraft survival
A quantitative assessment of the hazard associated with spacecraft charging and arcing on spacecraft systems is presented. A literature survey on arc discharge thresholds and characteristics was done and gaps in the data and requirements for additional experiments were identified. Calculations of coupling of arc discharges into typical spacecraft systems were made and the susceptibility of typical spacecraft to disruption by arc discharges was investigated. Design guidelines and recommended practices to reduce or eliminate the threat of malfunction and failures due to spacecraft charging/arcing were summarized
Early diagnostic suggestions improve accuracy of GPs:a randomised controlled trial using computer-simulated patients
Background: Designers of computerised diagnostic support systems (CDSSs) expect physicians to notice when they need advice and enter into the CDSS all information that they have gathered about the patient. The poor use of CDSSs and the tendency not to follow advice once a leading diagnosis emerges would question this expectation.Aim: To determine whether providing GPs with diagnoses to consider before they start testing hypotheses improves accuracy.Design and setting: Mixed factorial design, where 297 GPs diagnosed nine patient cases, differing in difficulty, in one of three experimental conditions: control, early support, or late support.Method: Data were collected over the internet. After reading some initial information about the patient and the reason for encounter, GPs requested further information for diagnosis and management. Those receiving early support were shown a list of possible diagnoses before gathering further information. In late support, GPs first gave a diagnosis and were then shown which other diagnoses they could still not discount.Results: Early support significantly improved diagnostic accuracy over control (odds ratio [OR] 1.31; 95% confidence interval [95%CI] = 1.03 to 1.66, P = 0.027), while late support did not (OR 1.10; 95% CI = 0.88 to 1.37). An absolute improvement of 6% with early support was obtained. There was no significant interaction with case difficulty and no effect of GP experience on accuracy. No differences in information search were detected between experimental conditions.Conclusion: Reminding GPs of diagnoses to consider before they start testing hypotheses can improve diagnostic accuracy irrespective of case difficulty, without lengthening information search
Die „Heliosschulen – Inklusive Universitätsschulen der Stadt Köln“: Gründungsgeschichte und aktuelle Entwicklungsperspektiven
Während zu dem Gründungskonzept der „Heliosschulen – Inklusive Universitätsschulen der Stadt Köln“ bereits vergleichsweise viele Publikationen insbesondere mit Blick auf Inklusion existieren (Reich, 2014, 2019; Reich, Asselhoven & Kargl, 2015), wollen wir in diesem Beitrag gewissermaßen einen Blick hinter die Kulissen werfen und weniger das pädagogische Konzept in den Vordergrund stellen, sondern die Entwicklung der Heliosschulen als Universitätsschulen. Zum einen werden wir die Gründungsgeschichte skizzieren und dazu auf ein zentrales Vorläuferprojekt an der Universität zu Köln eingehen. Zum anderen werden wir Meilensteine im Projektverlauf darstellen, wie den Spatenstich des Neubauvorhabens der Universitätsschule sowie aktuelle Initiativen der Wissenschaftlichen Leitung, die dazu dienen, die Universitätsschulen sowohl als Forschungsschulen als auch als Ausbildungsschulen zu konturieren.
While there are already many publications on the founding concept of the "Helios Schools – Inclusive University Schools of the City of Cologne", especially with regard to inclusion (Reich, 2014, 2018; Reich, Asselhoven & Kargl, 2015), in this article we want to take a look behind the scenes and focus less on the pedagogical concept and more on the development of the Helios Schools as university schools. On the one hand, we will outline the history of the founding of the Helios Schools and, in this context, we will look at a central predecessor project at the University of Cologne. On the other hand, we will present milestones in the course of the project, such as the ground-breaking for the construction of the new university schools and current initiatives of the scientific management, which serve to define the university schools both as research schools and as training schools
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Biomarker disclosure protocols in prodromal Alzheimer's disease clinical trials
IntroductionThe development of biomarkers for Alzheimer's disease (AD) has allowed researchers to increase sample homogeneity and test candidate treatments earlier in the disease. The integration of biomarker "screening" criteria should be met with a parallel implementation of standardized methods to disclose biomarker testing results to research participants; however, the extent to which protocolized disclosure occurs in trials is unknown.MethodsWe reviewed the literature to identify prodromal AD trials published in the past 10 years. From these, we quantified the frequency of biomarker disclosure reporting and the depth of descriptions provided.ResultsOf 30 published trials using positron emission tomography or cerebrospinal fluid-based amyloid positivity as an eligibility criterion, only one mentioned disclosure, with no details on methods.DiscussionPossible reasons for and implications of this information gap are discussed. Recommendations are provided for trialists considering biomarker screening as part of intervention trials focused on prodromal AD.HighlightsFew prodromal Alzheimer's disease (AD) trial papers discuss biomarker disclosure. Disclosure has implications for participants, family members, and trial success. Disclosure must be consistently integrated and reported in prodromal AD trials. Best practice guidelines and training resources for disclosure are needed
Designing consumer electronic products for the circular economy using recycled Acrylonitrile Butadiene Styrene (ABS): a case study
This study considers the feasibility of using 100% recycled Acrylonitrile Butadiene Styrene (rABS) in the caseworks of small consumer electronic products as a step towards more circular design and manufacturing. A Digitally Enhanced Cordless Telephone (DECT) handset was chosen as a representative example of such a product. Materials testing on the rABS demonstrated that 100% recycled ABS has similar properties to virgin ABS and can be substituted for virgin ABS as long as the product design allows for the slightly stiffer nature of the rABS and addresses issues of surface finish and ability to colour. By clearly understanding these issues at the outset of the design process, and by adapting the designs appropriately at the outset, it was possible to produce an rABS handset which was as robust and as cosmetically acceptable as one made of virgin ABS. This suggests that the recycled material could be used widely in this type of product and also at reduced cost to using virgin ABS. Furthermore, an abridged Life Cycle Analysis of the existing handset suggested that other issues associated with the environmental impact of the product could be relatively easily addressed at the design stage by considering energy use and end of life issues
Clinical features of spinal and bulbar muscular atrophy
Spinal and bulbar muscular atrophy is an X-linked motor neuron disease caused by a CAG repeat expansion in the androgen receptor gene. To characterize the natural history and define outcome measures for clinical trials, we assessed the clinical history, laboratory findings and muscle strength and function in 57 patients with genetically confirmed disease. We also administered self-assessment questionnaires for activities of daily living, quality of life and erectile function. We found an average delay of over 5 years from onset of weakness to diagnosis. Muscle strength and function correlated directly with serum testosterone levels and inversely with CAG repeat length, age and duration of weakness. Motor unit number estimation was decreased by about half compared to healthy controls. Sensory nerve action potentials were reduced in nearly all subjects. Quantitative muscle assessment and timed 2 min walk may be useful as meaningful indicators of disease status. The direct correlation of testosterone levels with muscle strength indicates that androgens may have a positive effect on muscle function in spinal and bulbar muscular atrophy patients, in addition to the toxic effects described in animal models
Assessment of joystick and wrist control in hand-held articulated laparoscopic prototypes
Various steerable instruments with flexible distal tip have been developed for laparoscopic surgery. The problem of steering such instruments, however, remains a challenge, because no study investigated which control method is the most suitable. This study was designed to examine whether thumb (joystick) or wrist control method is designated for prototypes of steerable instruments by means of motion analysis. Methods: Five experts and 12 novices participated. Each participant performed a needle-driving task in three directions with two prototypes (wrist and thumb) and a conventional instrument. Novices performed the tasks in three sessions, whereas experts performed one session only. The order of performing the tasks was determined by Latin squares design. Assessment of performance was done by means of five motion analysis parameters, a newly developed matrix for assigning penalty points, and a questionnaire. Results: The thumb-controlled prototype outperformed the wrist-controlled prototype. Comparison of the results obtained in each task showed that regarding penalty points, the up ? down task was the most difficult to perform. Conclusions: The thumb control is more suitable for steerable instruments than the wrist control. To avoid uncontrolled movements and difficulties with applying forces to the tissue while keeping the tip of the instrument at the constant angle, adding a ‘‘locking’’ feature is necessary. It is advisable not to perform the needle driving task in the up down directionBiomechanical EngineeringMechanical, Maritime and Materials Engineerin
Vitamin D Supplementation and Prevention of Type 2 Diabetes
BACKGROUND
Observational studies support an association between a low blood 25-hydroxyvitamin D level and the risk of type 2 diabetes. However, whether vitamin D supplementation lowers the risk of diabetes is unknown.
METHODS
We randomly assigned adults who met at least two of three glycemic criteria for prediabetes (fasting plasma glucose level, 100 to 125 mg per deciliter; plasma glucose level 2 hours after a 75-g oral glucose load, 140 to 199 mg per deciliter; and glycated hemoglobin level, 5.7 to 6.4%) and no diagnostic criteria for diabetes to receive 4000 IU per day of vitamin D3 or placebo, regardless of the baseline serum 25-hydroxyvitamin D level. The primary outcome in this time-to-event analysis was new-onset diabetes, and the trial design was event-driven, with a target number of diabetes events of 508.
RESULTS
A total of 2423 participants underwent randomization (1211 to the vitamin D group and 1212 to the placebo group). By month 24, the mean serum 25-hydroxyvitamin D level in the vitamin D group was 54.3 ng per milliliter (from 27.7 ng per milliliter at baseline), as compared with 28.8 ng per milliliter in the placebo group (from 28.2 ng per milliliter at baseline). After a median follow-up of 2.5 years, the primary outcome of diabetes occurred in 293 participants in the vitamin D group and 323 in the placebo group (9.39 and 10.66 events per 100 person-years, respectively). The hazard ratio for vitamin D as compared with placebo was 0.88 (95% confidence interval, 0.75 to 1.04; P = 0.12). The incidence of adverse events did not differ significantly between the two groups.
CONCLUSIONS
Among persons at high risk for type 2 diabetes not selected for vitamin D insufficiency, vitamin D3 supplementation at a dose of 4000 IU per day did not result in a significantly lower risk of diabetes than placebo. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; D2d ClinicalTrials.gov number, NCT01942694.
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