Publications

Ultrahigh molecular weight (UHMW) poly(methyl methacrylate) (PMMA) produced by plasma-initiated polymerization was investigated for its suitability as an electron-beam resist. Patterns exposed in this material at low to moderate doses (<5×10−6 C/cm2) displayed distorted features after development in a 1:1 mixture of methyl ethyl ketone and isopropanol. The distorted features are believed to originate from a combination of pattern swelling and stress relief.

Performance management systems (PMSYS) aid in improving the quality and efficiency of care, but little is known about factors that influence more robust PMSYS among physician organizations. Using a nationally representative survey of U.S. medical practices, we examined the extent to which organizational capabilities and external factors were associated with more developed PMSYS. Linear regression estimated the relative impact of these factors on PMSYS. On average, practices implemented a minority (32 points out of 100) of the PMSYS processes assessed. Practices evaluated ( p < .01) or financially incentivized by external entities ( p < .01), receiving data from health plans ( p < .01), participating in an accountable care organization ( p < .01), affiliating with an independent practice association and/or physician–hospital organization ( p < .01), and using health information technology ( p < .01) and chronic disease registries ( p < .01) to greater degrees had more robust PMSYS. PMSYS of medical practices are underdeveloped, although both external incentives and organizational capabilities may support PMSYS development.

Disturbances in sleep and affect are prominent features of bipolar disorder, even during interepisode periods. Few longitudinal studies have prospectively examined the relationship between naturally occurring sleep and affect, and no studies to date have done so during interepisode periods of bipolar disorder and using the entire set of "gold standard" sleep parameters. Participants diagnosed with bipolar I disorder who were interepisode (n = 32) and healthy controls (n = 36) completed diagnostic and symptom severity interviews, and a daily sleep and affect diary, as well as an actigraphy sleep assessment, for eight weeks (M = 54 days, ± 8 days). Mutual information analysis was used to assess the degree of statistical dependence, or coupling, between time series data of sleep and affect. As measured by actigraphy, longer sleep onset latency was coupled with higher negative affect more strongly in the bipolar group than in the control group. As measured by sleep diary, longer wakefulness after sleep onset and lower sleep efficiency were coupled with higher negative affect significantly more strongly in the bipolar group than in the control group. By contrast, there were no significant differences between groups in the degree of coupling between any measures of sleep and positive affect. Findings support the coupling of sleep disturbance and negative affect during interepisode bipolar disorder. Ongoing monitoring of sleep-affect coupling may provide an important target for intervention in bipolar disorder.

Along with the rapid development of hybrid electronic-photonic systems, multifunctional devices with dynamic responses have been widely investigated for improving many optoelectronic applications. For years, microelectro-opto-mechanical systems (MEOMS), one of the major approaches to realizing multifunctionality, have demonstrated profound reconfigurability and great reliability. However, modern MEOMS still suffer from limitations in modulation depth, actuation voltage, or miniaturization. Here, we demonstrate a new MEOMS multifunctional platform with greater than 50% optical modulation depth over a broad wavelength range. This platform is realized by a specially designed cantilever array, with each cantilever consisting of vanadium dioxide, chromium, and gold nanolayers. The abrupt structural phase transition of the embedded vanadium dioxide enables the reconfigurability of the platform. Diverse stimuli, such as temperature variation or electric current, can be utilized to control the platform, promising CMOS-compatible operating voltage. Multiple functionalities, including an active enhanced absorber and a reprogrammable electro-optic logic gate, are experimentally demonstrated to address the versatile applications of the MEOMS platform in fields such as communication, energy harvesting, and optical computing.

The present study investigates whether interepisode mood regulation impairment contributes to disturbances in sleep onset latency (SOL) and rapid eye movement (REM) sleep. Individuals with interepisode bipolar disorder (n = 28) and healthy controls (n = 28) slept in the laboratory for 2 baseline nights, a happy mood induction night, and a sad mood induction night. There was a significant interaction whereby on the happy mood induction night the bipolar group exhibited significantly longer SOL than did the control group, while there was no difference on the baseline nights. In addition, control participants exhibited shorter SOL on the happy mood induction night compared to the baseline nights, a finding that was not observed in the bipolar group. On the sad mood induction night, participants in both groups had shorter SOL and increased REM density when compared to the baseline nights. Bipolar participants exhibited heightened REM density compared to control participants on both nights. These results raise the possibility that regulation of positive stimuli may be a contributor to difficulties with SOL, while hyperactivity may be characteristic of REM sleep.

Monte-Carlo sampling of lattice model Hamiltonians is a well-established technique in statistical mechanics for studying the configurational entropy of crystalline materials. When species to be distributed on the lattice model carry charge, the charge balance constraint on the overall system prohibits single-site Metropolis exchanges in MC. In this article, we propose two methods to perform MC sampling in the grand-canonical ensemble in the presence of a charge-balance constraint. The table-exchange method (TE) constructs small charge-conserving excitations, and the square-charge bias method (SCB) allows the system to temporarily drift away from charge neutrality. We illustrate the effect of internal hyper-parameters on the efficiency of these algorithms and suggest practical strategies on how to apply these algorithms to real applications.