Existing treatment strategies: does noncompliance make a difference?

Although published literature shows a clear relationship between poor patient compliance with antihypertensive medication and failure to achieve blood pressure control, the association between treatment choices and compliance is less clear. Patient behavior in randomized controlled trials differs from that in actual practice; studies of this difference are therefore required to consider real-world evidence. Studies of actual practice have used a variety of measures of patient behavior, which makes comparisons difficult. In addition, they often have mingled patients receiving antihypertensive treatment for the first time and established hypertensive patients--groups that generally have quite different levels of compliance. This article briefly reviews the literature concerning therapeutic choices and patient compliance with hypertensive medications, including a recent study of persistence using treatment data from the provincial health plan of Saskatchewan, Canada. The Saskatchewan analysis was a rigorous examination of actual practice treatment for hypertension, which demonstrated that angiotensin-converting enzyme inhibitors were associated with the highest 1- and 4.5-year persistence rates and the lowest discontinuation rates among calcium antagonists, beta-blockers and diuretics. These findings may hold important implications for physicians when choosing an initial antihypertensive therapy, and point to the potential importance of the excellent safety and tolerability profiles of new antihypertensive therapies.     

Juggling power control [automatic generation control]

The optimization of electric power generation and transmission in real time, known as automatic generation control (AGC), is normally implemented through the application of a sophisticated real-time computer system known as an energy management system (EMS). A decision by Pacific Gas and Electric Co. to install an EMS is used to illustrate the factors that necessitate such an approach. The operation of modern EMSs is examined     

Influence of acetaldehyde on growth and acetoin production by Leuconostoc citrovorum

Addition of acetaldehyde (100 μg/ml) to glucose-citrate broth stimulated growth and approximately doubled the production of acetoin plus diacetyl by Leuconostoc citrovorum. Radioactive acetaldehyde was converted to ethanol; the acetoin, diacetyl and acetic acid produced were not radioactive. A discussion of the mechanisms by which species of Leuconostoc utilize citrate and carbohydrate suggests that the added acetaldehyde enhanced production of acetoin and diacetyl by increasing the availability of hydroxyethylthiamine pyrophosphate and acetyl-coenzyme A, and that it stimulated growth by permitting greater conversion of acetyl-coenzyme A and acetyl-phosphate to acetate and adenosine 5′-triphosphate.     

Carbon reduction in triethylarsenic-grown GaAs films using chemically activated arsine as a co-reagent

N-type gallium arsenide films grown from triethylarsenic (Et₃As) and trimethylgallium (Me₃Ga) are generally of poor quality (μ_77K(max) = 16,100 cm²/V-s) and are severely contaminated with carbon (>10¹⁸ cm⁻³), whereas films grown using a mixture of triethylarsenic and arsine (AsH₃) with Me₃Ga are typically of high purity (β_77K(max) = 60,000 cm²/V-s) and contain significantly reduced carbon levels (~mid-10¹⁵ cm^-3). These differences in film purity are due to the inherent growth chemistry of each reagent mixture. The respective growth chemistries of these reagent systems have been inferred from a series of decomposition experiments carried out under pseudo-growth conditions, and the differences in growth chemistry are consistent with the differences in corresponding epilayer purity. Triethylarsenic appears to decompose primarily via a bond homolysis reaction to generate alkyl-containing radical species, which can react with a growing GaAs epilayer to cause severe carbon contamination. In the Et₃As/AsH₃ coreagent system, the Et₃As reagent decomposes to produce these alkyl-containing radical intermediates, but they then apparently react further with the arsine co-reagent to generate reactive arsenic hydride radicals under relatively facile conditions. These reactive arsenic-hydride radical species can contribute to the GaAs growth process without introducing carbon into the resultant films.     

A hierarchical process-dissociation model.

In fitting the process-dissociation model (L. L. Jacoby, 1991) to observed data, researchers aggregate outcomes across participant, items, or both. T. Curran and D. L. Hintzman (1995) demonstrated how biases from aggregation may lead to artifactual support for the model. The authors develop a hierarchical process-dissociation model that does not require aggregation for analysis. Most importantly, the Curran and Hintzman critique does not hold for this model. Model analysis provides for support of process dissociation--selective influence holds, and there is a dissociation in correlation patterns among participants and items. Items that are better recollected also elicit higher automatic activation. There is no correlation, however, across participants; that is, participants with higher recollection have no increased tendency toward automatic activation. The critique of aggregation is not limited to process dissociation. Aggregation distorts analysis in many nonlinear models, including signal detection, multinomial processing tree models, and strength models. Hierarchical modeling serves as a general solution for accurately fitting these psychological-processing models to data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flaw signature estimation in ultrasonic nondestructive evaluation using the Wiener filter with limited prior information

Flaw signals measured in ultrasonic testing include the effects of the measurements system and are corrupted by noise. The measurement system response is both bandlimited and frequency dependent within the bandwidth, resulting in measured signals which are blurred and distorted estimates of actual flaw signatures. The Wiener filter can be used to estimate the flaw's scattering amplitude by removing the effect of the measurement system in the presence of noise. A method is presented for implementing an optimal form of the Wiener filter that requires only estimates of the noise distribution parameters. The theoretical error for scattering amplitude estimation, assuming various levels of available prior information, is analyzed. Three estimation techniques, one a maximum-likelihood based method and the other two residual-sum-of-squares methods, are formulated and tested. The results demonstrate that any of the three approaches could be used to optimally implement the alternative form of the Wiener filter with limited prior information.