Probabilistic modeling of noise transfer characteristics in digital circuits

Device scaling, the driving force of CMOS technology, led to continuous decrease in the energy level representing logic states. The resulting small noise margins in combination with increasing problems regarding the supply voltage stability and process variability creates a design conflict between efficiency and reliability. This conflict is expected to rise more in future technologies. Current research approaches on fault-tolerance architectures and countermeasures at circuit level, unfortunately, cause a significant area and energy penalty without guaranteeing absence of errors. To overcome this problem, it seems to be attractive to tolerate bit errors at circuit level and employ error handling methods at higher system levels. To do this, an estimate of the bit error rate (BER) at circuit level is necessary. Due to the size of the circuits, Monte Carlo simulation suffers from impractical runtimes. Therefore the needed modeling scheme is proposed. The model allows a probabilistic estimation of error rates at circuit level taking into account statistical effects ranging from supply noise and electromagnetic coupling to process variability within reasonable runtimes

Money in monetary policy design: monetary cross-checking in the New-Keynesian model

In the New-Keynesian model, optimal interest rate policy under uncertainty is formulated without reference to monetary aggregates as long as certain standard assumptions on the distributions of unobservables are satisfied. The model has been criticized for failing to explain common trends in money growth and inflation, and that therefore money should be used as a cross-check in policy formulation (see Lucas (2007)). We show that the New-Keynesian model can explain such trends if one allows for the possibility of persistent central bank misperceptions. Such misperceptions motivate the search for policies that include additional robustness checks. In earlier work, we proposed an interest rate rule that is near-optimal in normal times but includes a cross-check with monetary information. In case of unusual monetary trends, interest rates are adjusted. In this paper, we show in detail how to derive the appropriate magnitude of the interest rate adjustment following a significant cross-check with monetary information, when the New-Keynesian model is the central bank’s preferred model. The cross-check is shown to be effective in offsetting persistent deviations of inflation due to central bank misperceptions. Keywords: Monetary Policy, New-Keynesian Model, Money, Quantity Theory, European Central Bank, Policy Under Uncertaint

Antibiotics for coughing in general practice: a questionnaire study to quantify and condense the reasons for prescribing

BACKGROUND: Antibiotics are being overprescribed in ambulant care, especially for respiratory tract infections (RTIs). Gaining insight into the actual reasons for prescribing remains important for the design of effective strategies to optimise antibiotic prescribing. We aimed to determine items of importance for the antibiotic prescribing decision and to make them operational for an intervention trial. METHODS: A postal questionnaire based upon focus group findings was sent to 316 Flemish general practitioners (GPs). On a verbal rating scale the GPs scored to what extent they consider the questionnaire items in decision making in case of suspected RTI in a coughing patient and how strongly the items support or counter antibiotic treatment. Factor analysis was used to condense the data. The relative importance of the yielded operational factors was assessed using Wilcoxon Matched Pairs test. RESULTS: 59.5% completed the study. Response group characteristics (mean age: 42.8 years; 65.9% men) approximated that of all Flemish GPs. Participants considered all the items included in the questionnaire: always the operational factor 'lung auscultation', often 'whether or not there is something unusual happening' – both medical reasons – and to a lesser extent 'non-medical reasons' (P < 0.001). Non-medical as well as medical reasons support antibiotic treatment, but non-medical reasons to a lesser extent (P < 0.001). CONCLUSION: This study quantified, condensed and confirmed the findings of previous focus group research. Practice guidelines and interventions to optimise antibiotic prescribing have to take non-medical reasons into account

Quantification of the performance of iterative and non-iterative computational methods of locating partial discharges using RF measurement techniques

Partial discharge (PD) is an electrical discharge phenomenon that occurs when the insulation materialof high voltage equipment is subjected to high electric field stress. Its occurrence can be an indication ofincipient failure within power equipment such as power transformers, underground transmission cableor switchgear. Radio frequency measurement methods can be used to detect and locate discharge sourcesby measuring the propagated electromagnetic wave arising as a result of ionic charge acceleration. Anarray of at least four receiving antennas may be employed to detect any radiated discharge signals, thenthe three dimensional position of the discharge source can be calculated using different algorithms. These algorithms fall into two categories; iterative or non-iterative. This paper evaluates, through simulation, the location performance of an iterative method (the standardleast squares method) and a non-iterative method (the Bancroft algorithm). Simulations were carried outusing (i) a "Y" shaped antenna array and (ii) a square shaped antenna array, each consisting of a four-antennas. The results show that PD location accuracy is influenced by the algorithm's error bound, thenumber of iterations and the initial values for the iterative algorithms, as well as the antenna arrangement for both the non-iterative and iterative algorithms. Furthermore, this research proposes a novel approachfor selecting adequate error bounds and number of iterations using results of the non-iterative method, thus solving some of the iterative method dependencies

On the dispersion of a drug delivered intrathecally in the spinal canal

This paper investigates the transport of a solute carried by the cerebrospinal fluid (CSF) in the spinal canal. The analysis is motivated by the need for a better understanding of drug dispersion in connection with intrathecal drug delivery (ITDD), a medical procedure used for treatment of some cancers, infections and pain, involving the delivery of the drug to the central nervous system by direct injection into the CSF via the lumbar route. The description accounts for the CSF motion in the spinal canal, described in our recent publication (Sánchez et al., J. Fluid Mech., vol. 841, 2018, pp. 203-227). The Eulerian velocity field includes an oscillatory component with angular frequency omega, equal to that of the cardiac cycle, and associated tidal volumes that are a factor epsilon 1 smaller than the total CSF volume in the spinal canal, with the small velocity corrections resulting from convective acceleration providing a steady-streaming component with characteristic residence times of order epsilon 2omega 1 omega 1 . An asymptotic analysis for epsilon 1 accounting for the two time scales omega 1 and epsilon 2omega 1 is used to investigate the prevailing drug-dispersion mechanisms and their dependence on the solute diffusivity, measured by the Schmidt number S. Convective transport driven by the time-averaged Lagrangian velocity, obtained as the sum of the Eulerian steady-streaming velocity and the Stokes-drift velocity associated with the non-uniform pulsating flow, is found to be important for all values of S. By way of contrast, shear-enhanced Taylor dispersion, which is important for values of S of order unity, is shown to be negligibly small for the large values S epsilon 2 1 corresponding to the molecular diffusivities of all ITDD drugs. Results for a model geometry indicate that a simplified equation derived in the intermediate limit 1 S epsilon 2 provides sufficient accuracy under most conditions, and therefore could constitute an attractive reduced model for future quantitative analyses of drug dispersion in the spinal canal. The results can be used to quantify dependences of the drug-dispersion rate on the frequency and amplitude of the pulsation of the intracranial pressure, the compliance and specific geometry of the spinal canal and the molecular diffusivity of the drug.C.M.-B. acknowledges the financial support provided by the Spanish MINECO (Secretaría de Estado de Investigación, Desarrollo e Innovación) through grants DPI2014-59292-C3-3 and DPI2017-88201-C3-2-R, co-financed by the European Regional Development Fund (ERDF)