Word-level Symbolic Trajectory Evaluation

Symbolic trajectory evaluation (STE) is a model checking technique that has been successfully used to verify industrial designs. Existing implementations of STE, however, reason at the level of bits, allowing signals to take values in {0, 1, X}. This limits the amount of abstraction that can be achieved, and presents inherent limitations to scaling. The main contribution of this paper is to show how much more abstract lattices can be derived automatically from RTL descriptions, and how a model checker for the general theory of STE instantiated with such abstract lattices can be implemented in practice. This gives us the first practical word-level STE engine, called STEWord. Experiments on a set of designs similar to those used in industry show that STEWord scales better than word-level BMC and also bit-level STE.Comment: 19 pages, 3 figures, 2 tables, full version of paper in International Conference on Computer-Aided Verification (CAV) 201

Parasites and sex

Book ChapterParasites of many kinds have long been recognized as important regulators of population size (e.g., May, 1983b), but only during the last decade or two have they been widely viewed as the protagonists in fast-paced (and long-running) evolutionary thrillers involving subtle features of the biochemistry, anatomy, and behavior of their hosts. On this view, their power as agents of evolution derives from their ubiquity and from the great amounts of mortality they can cause (which are also the properties that make them effective agents of population regulation) and, just as importantly, from their imperfect (but improvable) abilities to defeat the imperfect (but improvable) defenses of their hosts. Thus each party is expected to experience the other as a changeable (and generally worsening) part of its environment

A variational approach to the stochastic aspects of cellular signal transduction

Cellular signaling networks have evolved to cope with intrinsic fluctuations, coming from the small numbers of constituents, and the environmental noise. Stochastic chemical kinetics equations govern the way biochemical networks process noisy signals. The essential difficulty associated with the master equation approach to solving the stochastic chemical kinetics problem is the enormous number of ordinary differential equations involved. In this work, we show how to achieve tremendous reduction in the dimensionality of specific reaction cascade dynamics by solving variationally an equivalent quantum field theoretic formulation of stochastic chemical kinetics. The present formulation avoids cumbersome commutator computations in the derivation of evolution equations, making more transparent the physical significance of the variational method. We propose novel time-dependent basis functions which work well over a wide range of rate parameters. We apply the new basis functions to describe stochastic signaling in several enzymatic cascades and compare the results so obtained with those from alternative solution techniques. The variational ansatz gives probability distributions that agree well with the exact ones, even when fluctuations are large and discreteness and nonlinearity are important. A numerical implementation of our technique is many orders of magnitude more efficient computationally compared with the traditional Monte Carlo simulation algorithms or the Langevin simulations.Comment: 15 pages, 11 figure

Models of Sex Ratio Evolution

The basic principle th a t explains w hy balanced sex ratios evolve so often was described in a lim ited and tentative way by D arw in (1871), fa rth e r devel oped by Karl Dtising (1883, 1884) and several early tw e n tie th cen tu ry authors, and th e n sum m arized concisely by RA Fisher in The Genetical Theory of Natural Selection (1930) (Edwards 199

The bicycle wheel analogy for linear closures of small suborbital cheek defects

Primary closure of suborbital skin defects can cause tension along the closure resulting in ectropion. The bicycle wheel analogy is a simple yet effective guide to aid in reducing tension vectors resulting in ectropion

Selective production of hydrogen peroxide and oxidation of hydrogen sulfide in an unbiased solar photoelectrochemical cell

A solar-to-chemical conversion process is demonstrated using a photoelectrochemical cell without external bias for selective oxidation of hydrogen sulfide (H2S) to produce hydrogen peroxide (H2O2) and sulfur (S). The process integrates two redox couples anthraquinone/anthrahydroquinone and I−/I3−, and conceptually illustrates the remediation of a waste product for producing valuable chemicals

A Multi-Site Survey Study of Patient Satisfaction with Teledermatology

Introduction. Telemedicine has been of heightened focus due to spikes in usage during the COVID-19 pandemic. Disparities in health care may affect patient satisfaction with this resource depending on factors such as patient race, age, or socioeconomic background. The purpose of this study was to analyze patient satisfaction with teledermatology to identify any differences in satisfaction based on race, age, and income during the COVID-19 pandemic period. Methods. A 21-question, IRB-approved survey was administered to patients at two academic dermatology clinics in Kansas City. Patient satisfaction was measured using a five-point Likert scale. Results. A total of 64 completed surveys were analyzed (17.8% response rate). Most of the participants were female (n = 48, 75%), age 45 to 60 (n = 17, 26.6%), and reported White for race (n = 55, 85.9%). Overall, 73.4% (n = 47) of patients reported being satisfied with their visit. However, only 38.7% (n = 24) of participants were likely to choose a video over an in-person visit. Reasons for low patient satisfaction included concerns regarding ability to perform an accurate physical exam with a video visit (n = 9, 14.1%), receiving inadequate care (n = 4, 6.3%), protected privacy (n = 3, 4.7%), and provider understanding the patient (n = 2, 3.1%). Conclusions. Our findings were similar to prior studies stating no difference in patient satisfaction with regards to age, income, or race and patients reporting high satisfaction with teledermatology appointments despite a preference for in-person dermatology visits. Future studies with a larger diverse cohort of participants are needed to elucidate and address possible disparities associated with teledermatology use

Understanding physicians’ behavior toward alerts about nephrotoxic medications in outpatients: a cross-sectional analysis

Background: Although most outpatients are relatively healthy, many have chronic renal insufficiency, and high override rates for suggestions on renal dosing have been observed. To better understand the override of renal dosing alerts in an outpatient setting, we conducted a study to evaluate which patients were more frequently prescribed contraindicated medications, to assess providers’ responses to suggestions, and to examine the drugs involved and the reasons for overrides. Methods: We obtained data on renal alert overrides and the coded reasons for overrides cited by providers at the time of prescription from outpatient clinics and ambulatory hospital-based practices at a large academic health care center over a period of 3 years, from January 2009 to December 2011. For detailed chart review, a group of 6 trained clinicians developed the appropriateness criteria with excellent inter-rater reliability (κ = 0.93). We stratified providers by override frequency and then drew samples from the high- and low-frequency groups. We measured the rate of total overrides, rate of appropriate overrides, medications overridden, and the reason(s) for override. Results: A total of 4120 renal alerts were triggered by 584 prescribers in the study period, among which 78.2% (3,221) were overridden. Almost half of the alerts were triggered by 40 providers and one-third was triggered by high-frequency overriders. The appropriateness rates were fairly similar, at 28.4% and 31.6% for high- and low-frequency overriders, respectively. Metformin, glyburide, hydrochlorothiazide, and nitrofurantoin were the most common drugs overridden. Physicians’ appropriateness rates were higher than the rates for nurse practitioners (32.9% vs. 22.1%). Physicians with low frequency override rates had higher levels of appropriateness for metformin than the high frequency overriders (P = 0.005). Conclusion: A small number of providers accounted for a large fraction of overrides, as was the case with a small number of drugs. These data suggest that a focused intervention targeting primarily these providers and medications has the potential to improve medication safety