Jitter in DLL-Based Clock Multipliers caused by Delay Cell Mismatch

This paper describes the jitter problem in\ud DLL-based clock multipliers that arises due to stochastic\ud mismatch in the delay cells that are used in the Voltage Controlled\ud Delay Line of the DLL [1]. An analysis is presented\ud that relates the stochastic spread of the delay of the cells to\ud the output jitter of the clock multiplier. This analysis shows\ud that relative time deviations are highest in the middle of the\ud Delay Line and proportional to the square root of the frequency\ud multiplication factor of the structure. A circuit design\ud technique, called Impedance Level Scaling, is presented\ud that allows the designer to optimize the noise and mismatch\ud behavior of a circuit independent of other specifications such\ud as speed and linearity. Applying this technique on delay cell\ud design yields a direct trade-off between noise induced jitter\ud and power usage, and between stochastic mismatch induced\ud jitter and power usage

Technical Comment on "Saccadic eye movement performance as an indicator of driving ability in elderly drivers".

ISSN:1424-7860ISSN:1424-399

Instruments for investigating fitness to drive - needs and expectations in primary care: a qualitative study

Background: Primary care physicians are often requested to assess their patients' fitness to drive. Little is however known on their needs to help them in this task. Aims: The aim of this study is to develop theories on needs, expectations, and barriers for clinical instruments helping physicians assess fitness to drive in primary care. Methods: This qualitative study used semi-structured interviews to investigate needs and expectations for instruments used to assess fitness to drive. From August 2011 to April 2013, we recorded opinions from five experts in traffic medicine, five primary care physicians, and five senior drivers. All interviews were integrally transcribed. Two independent researchers extracted, coded, and stratified categories relying on multi-grounded theory. All participants validated the final scheme. Results: Our theory suggests that for an instruments assessing fitness to drive to be implemented in primary care, it need to contribute to the decisional process. This requires at least five conditions: 1) it needs to reduce the range of uncertainty, 2) it needs to be adapted to local resources and possibilities, 3) it needs to be accepted by patients, 4) choices of tasks need to adaptable to clinical conditions, 5) and interpretation of results need to remain dependant of each patient's context. Discussion and conclusions: Most existing instruments assessing fitness to drive are not designed for primary care settings. Future instruments should also aim to support patient-centred dialogue, help anticipate driving cessation, and offer patients the opportunity to freely take their own decision on driving cessation as often as possible

Cross-sectional study assessing the addition of contrast sensitivity to visual acuity when testing for fitness to drive.

The aim of this study is to quantify the importance of loss of contrast sensitivity (CS) and its relationship to loss of visual acuity (VA), driving restrictions and daytime, on-road driving evaluations in drivers aged 70+. A predictive cross-sectional study. Volunteer participants to a drivers' refresher course for adults aged 70+ delivered by the Swiss Automobile Club in western Switzerland from 2011 to 2013. 162 drivers, male and female, aged 70 years or older. We used a vision screener to estimate VA and the The Mars Letter Contrast Sensitivity Test to test CS. We asked drivers to report whether they found five driving restrictions useful for their condition; restrict driving to known roads, avoid driving on highways, avoid driving in the dark, avoid driving in dense traffic and avoid driving in fog. All participants also underwent a standardised on-road evaluation carried out by a driving instructor. Moderate to severe loss of CS for at least one eye was frequent (21.0% (95% CI 15.0% to 28.1%)) and often isolated from a loss of VA (11/162 cases had a VA ≥0.8 decimal and a CS of ≤1.5 log(CS); 6.8% (95% CI 3.4% to 11.8%)). Drivers were more likely (R <sup>2</sup> =0.116, P=0.004) to report a belief that self-imposed driving restrictions would be useful if they had reduced CS in at least one eye. Daytime evaluation of driving performance seems limited in its ability to correctly identify difficulties related to CS loss (VA: R <sup>2</sup> =0.004, P=0.454; CS: R <sup>2</sup> =0.006, P=0.332). CS loss is common for older drivers. Screening CS and referring for cataract surgery even in the absence of VA loss could help maintain mobility. Reduced CS and moderate reduction of VA were both poor predictors of daytime on-road driving performances in this research study

The trail making test as a screening instrument for driving performance in older drivers; a translational research.

BACKGROUND: In many countries, primary care physicians determine whether or not older drivers are fit to drive. Little, however, is known regarding the effects of cognitive decline on driving performance and the means to detect it. This study explores to what extent the trail making test (TMT) can provide indications to clinicians about their older patients' on-road driving performance in the context of cognitive decline. METHODS: This translational study was nested within a cohort study and an exploratory psychophysics study. The target population of interest was constituted of older drivers in the absence of important cognitive or physical disorders. We therefore recruited and tested 404 home-dwelling drivers, aged 70 years or more and in possession of valid drivers' licenses, who volunteered to participate in a driving refresher course. Forty-five drivers also agreed to undergo further testing at our lab. On-road driving performance was evaluated by instructors during a 45 minute validated open-road circuit. Drivers were classified as either being excellent, good, moderate, or poor depending on their score on a standardized evaluation of on-road driving performance. RESULTS: The area under the receiver operator curve for detecting poorly performing drivers was 0.668 (CI95% 0.558 to 0.778) for the TMT-A, and 0.662 (CI95% 0.542 to 0.783) for the TMT-B. TMT was related to contrast sensitivity, motion direction, orientation discrimination, working memory, verbal fluency, and literacy. Older patients with a TMT-A ≥ 54 seconds or a TMT-B ≥ 150 seconds have a threefold (CI95% 1.3 to 7.0) increased risk of performing poorly during the on-road evaluation. TMT had a sensitivity of 63.6%, a specificity of 64.9%, a positive predictive value of 9.5%, and a negative predictive value of 96.9%. CONCLUSION: In screening settings, the TMT would have clinicians uselessly consider driving cessation in nine drivers out of ten. Given the important negative impact this could have on older drivers, this study confirms the TMT not to be specific enough for clinicians to justify driving cessation without complementary investigations on driving behaviors

Management of late-preterm and term infants with hyperbilirubinaemia in resource-constrained settings.

Hyperbilirubinaemia is a ubiquitous transitional morbidity in the vast majority of newborns and a leading cause of hospitalisation in the first week of life worldwide. While timely and effective phototherapy and exchange transfusion are well proven treatments for severe neonatal hyperbilirubinaemia, inappropriate or ineffective treatment of hyperbilirubinaemia, at secondary and tertiary hospitals, still prevails in many poorly-resourced countries accounting for a disproportionately high burden of bilirubin-induced mortality and long-term morbidity. As part of the efforts to curtail the widely reported risks of frequent but avoidable bilirubin-induced neurologic dysfunction (acute bilirubin encephalopathy (ABE) and kernicterus) in low and middle-income countries (LMICs) with significant resource constraints, this article presents a practical framework for the management of late-preterm and term infants (≥ 35 weeks of gestation) with clinically significant hyperbilirubinaemia in these countries particularly where local practice guidelines are lacking. Standard and validated protocols were followed in adapting available evidence-based national guidelines on the management of hyperbilirubinaemia through a collaboration among clinicians and experts on newborn jaundice from different world regions. Tasks and resources required for the comprehensive management of infants with or at risk of severe hyperbilirubinaemia at all levels of healthcare delivery are proposed, covering primary prevention, early detection, diagnosis, monitoring, treatment, and follow-up. Additionally, actionable treatment or referral levels for phototherapy and exchange transfusion are proposed within the context of several confounding factors such as widespread exclusive breastfeeding, infections, blood group incompatibilities and G6PD deficiency, which place infants at high risk of severe hyperbilirubinaemia and bilirubin-induced neurologic dysfunction in LMICs, as well as the limited facilities for clinical investigations and inconsistent functionality of available phototherapy devices. The need to adjust these levels as appropriate depending on the available facilities in each clinical setting and the risk profile of the infant is emphasised with a view to avoiding over-treatment or under-treatment. These recommendations should serve as a valuable reference material for health workers, guide the development of contextually-relevant national guidelines in each LMIC, as well as facilitate effective advocacy and mobilisation of requisite resources for the optimal care of infants with hyperbilirubinaemia at all levels

Information Needs and Concerns of Patients with Inflammatory Bowel Disease: What Can We Learn from Participants in a Bilingual Clinical Cohort?

BACKGROUND: Inflammatory Bowel Disease (IBD) patients are confronted with needs and concerns related to their disease. AIM: To explore information expectations of patients included in a national bilingual IBD cohort in Switzerland (SIBDC). METHODS: This is a mixed-methods study, comprising 1) a semi-narrative survey sent to 1506 patients from the SIBDC and 2) two focus groups conducted with 14 patients to explore and assess the relevance of the survey's findings. Data collected within the framework of the SIBDC was used to characterize survey's responders. RESULTS: 728 patients (48%) replied to the survey: 52.5% females, 56% Crohn's disease (CD), 87% secondary/tertiary level educated, 70% full/part-time employed. On average, 47% of patients sought for information, regardless of the disease stage; 27% of them were dissatisfied with information received at the time of first symptoms. During flares, 43% were concerned about drugs and therapies; in remission, 57% had concerns on research and developments; 27% searched for information linked to daily disease management. Information-seeking increased when active disease, for CD with high levels of perceived stress (OR = 2.47; p = 0.003), and for all with higher posttraumatic stress symptoms. The focus groups confirmed a perceived lack of information about general functioning, disease course, treatments and their risks, extra-intestinal symptoms and manifestations. CONCLUSIONS: Information remains insufficient for IBD patients. Lack of information in specific domains can potentially cause stress and hinder detection of symptoms. Better information should be considered as a potentially important component in improving patients' outcomes in IBD

Meeting physicians' needs: a bottom-up approach for improving the implementation of medical knowledge into practice.

Multiple barriers to knowledge translation in medicine have been identified (ranging from information overload to abstraction of models), leading to important implementation gaps. This study aimed at assessing the suggestions of practicing physicians for possible improvements of knowledge translation (KT) effectiveness into clinical practice. We used a mixed methods design. French- German- and Italian-speaking general practitioners, psychiatrists, orthopaedic surgeons, cardiologists, and diabetologists practicing in Switzerland were interrogated through semi-structured interviews, focus group discussions, and an online survey. A total of 985 physicians from three regions of Switzerland participated in the online survey, whereas 39 participated in focus group discussions and 14 in face-to-face interviews. Physicians expressed limitations and difficulties related to KT into their daily practice. Several barriers were identified, including influence and pressure of pharmaceutical companies, non-publication of negative results, mismatch between guidelines and practice, education gaps, and insufficient collaboration between research and practice. Suggestions to overcome barriers were improving education concerning the evaluation of scientific publications, expanding applicability of guidelines, having free and easy access to independent journals, developing collaborations between research and practice, and creating tools to facilitate access to medical information. Our study provides suggestions for improving KT into daily medical practice, matching the views, needs and preferences of practicing physicians. Responding to suggestions for improvements brought up by physicians may lead to better knowledge translation, higher professional satisfaction, and better healthcare outcomes