Determination of infinite dilution diffusion and activity coefficients of solvents in polystyrene by inverse gas chromatography on a capillary column

Infinite dilution activity and diffusion coefficients of several solvents in polystyrene have been measured by inverse gas chromatographic on a capillary column for temperatures between 110 and 170°C. Chromatographic data have been treated according to Khan's model, evaluating the contribution to the peak broadening due to radial and axial molecular diffusion in the mobile phase, radial diffusion in the stationary phase, and interfacial mass transfer resistance. Four capillary columns have been prepared with coating thickness ranging from 0.5 to 3.3 microns in order to determine the minimum thickness necessary to obtain reliable measurements of the diffusion coefficient of the solvent in the polymer in every possible experimental condition. Our experimental data are in considerable agreement with the data already available in the literature, obtained by static and chromatographic methods. © 1994 John Wiley & Sons, Inc.     

Impairment in risk-sensitive decision-making in older suicide attempters with depression.

Suicidal behavior is a potentially lethal complication of late-life depression. In younger adults, suicide has been linked to abnormal decision-making ability. Given that there are substantial age-related decreases in decision-making ability, and that older adults experience environmental stressors that require effective decision-making, we reasoned that impaired decision-making may be particularly relevant to suicidal behavior in the elderly. We thus compared performance on a probabilistic decision-making task that does not involve working memory (“Cambridge Gamble Task”) in four groups of older adults: (1) individuals with major depression and a history of suicide attempt (n = 25), (2) individuals with major depression with active suicidal ideation but no suicide attempt (n = 13), (3) individuals with major depression without suicidality (n = 35), and (4) nondepressed control subjects (n = 22). There was a significant effect of group on quality of decision-making, whereby the suicide attempters exhibited poorer ability to choose the likely outcome, compared with the nonsuicidal depressed and nondepressed comparison subjects. There were no group differences in betting behavior. The suicide attempters differed in several aspects of social problem-solving on a self-report scale. Quality of decision-making was negatively correlated with the score on the impulsive/careless problem-solving subscale. These data suggest that older suicide attempters have a deficit in risk-sensitive decision-making, extending observations in younger adults. More specifically, older suicide attempters seem to neglect outcome probability and make poor choices. These impairments may precipitate and perpetuate suicidal crisis in depressed elders. Identification of decision-making impairment in suicidal elders may help with designing effective interventions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Disseminated pulmonary ossification. Case report

Metaplastic pulmonary ossification is usually described as dendriform or nodular in patients with chronic inflammatory lung disease or long-standing pulmonary edema. We present a case of dendriform pulmonary ossification found accidentally at autopsy in a 66-year old man. In addition, some of the theories relating to the development of this rare phenomenon are discussed.     

Construction of maps with prescribed automorphism group

We show that given a finite group G a hypermap can be constructed having automorphism group isomorphic to G. The bipartite map of a modified version of this hypermap then affords a map with the same property.     

Practical-optimal control of a drum boiler power plant

Multivariable control of power plants has been studied by many researchers and also a number of practical applications have been presented in the last few years with the aim of improving the load following capabilities of thermal units. This paper summarizes the main results of an experimental application of optimal control to a drum boiler power plant at the Italian national electricity board. Referring to a previous work for the process model building, first a model reduction is performed with the main purpose of getting a simplified control structure. Then, an optimal regulator including feedforward and integral control is synthesized and some practical drawbacks of the synthesis are discussed with referrence to traditional control schemes leading to a reformulation of the optimal regulator which, while conserving optimality, exhibits a number of practical advantages and improved robustness against typical plant parameter variations. Since the motivation of the control structure reformulation is mostly derived from experimental results, field trials are reported where the performances of a well tuned coordinated control, of the classical optimal regulator and of the reformulated optimal control structure are compared. Perspectives of future industrial applications are briefly discussed in the conclusions.     

Properties of an Infrared‐Transparent MgO:Y2O3 Nanocomposite

A 50:50 vol% MgO–Y₂O₃ nanocomposite with ~150 nm grain size was prepared in an attempt to make 3–5 μm infrared‐transmitting windows with increased durability and thermal shock resistance. Flexure strength of the composite at 21°C is 679 MPa for 0.88 cm² under load. Hardness is consistent with that of the constituents with similar grain size. For 3‐mm‐thick material at 4.85 μm, the total scatter loss is 1.5%, forward scatter is 0.2%, and absorptance is 1.8%. Optical scatter below 2 μm is 100%. Variable intensity OH absorption (~6% absorptance) is observed near 3 μm. The refractive index is ~0.4% below the volume‐fraction‐weighted average of those of the constituents. Thermal expansion is equal to the volume‐fraction‐weighted average of expansion of the constituents. Specific heat capacity is equal to the mass‐fraction‐weighted average of heat capacities of the constituents. Thermal conductivity lies between those of the constituents up to 1200 K. Elastic constants lie between those of the constituents. The Hasselman mild thermal shock resistance parameter for the composite is twice as great as that of common 3–5 μm window materials, but half as great as that of c‐plane sapphire.     

Inferring the reproduction number using the renewal equation in heterogeneous epidemics

Real-time estimation of the reproduction number has become the focus of modelling groups around the world as the SARS-CoV-2 pandemic unfolds. One of the most widely adopted means of inference of the reproduction number is via the renewal equation, which uses the incidence of infection and the generation time distribution. In this paper, we derive a multi-type equivalent to the renewal equation to estimate a reproduction number which accounts for heterogeneity in transmissibility including through asymptomatic transmission, symptomatic isolation and vaccination. We demonstrate how use of the renewal equation that misses these heterogeneities can result in biased estimates of the reproduction number. While the bias is small with symptomatic isolation, it can be much larger with asymptomatic transmission or transmission from vaccinated individuals if these groups exhibit substantially different generation time distributions to unvaccinated symptomatic transmitters, whose generation time distribution is often well defined. The bias in estimate becomes larger with greater population size or transmissibility of the poorly characterized group. We apply our methodology to Ebola in West Africa in 2014 and the SARS-CoV-2 in the UK in 2020–2021.     

What works in coping with HIV? A meta-analysis with implications for coping with serious illness.

Knowledge of effective ways of coping with HIV is critical to help individuals with HIV maintain the best possible psychological and physical well-being. The purpose of the present article is to determine, through meta-analysis, the strength of the evidence regarding 2 questions: (a) Which types of coping are related to psychological and physical well-being among people with HIV? and (b) Do contextual (pre?post introduction of highly active antiretroviral therapies [HAART]; time since diagnosis), measurement (HIV-related event vs. generic prompts for coping measurement), or individual (gender) variables affect the extent to which coping is related to physical and psychological well-being? The authors' analysis demonstrates that Direct Action and Positive Reappraisal were consistently associated with better outcomes in people coping with HIV across affective, health behavior, and physical health categories. In contrast, disengagement forms of coping, such as Behavioral Disengagement and Use of Alcohol or Drugs to Cope, were consistently associated with poorer outcomes. The findings also indicate that in some cases, coping effectiveness was dependent on contextual factors, including time since diagnosis and the advent of HAART. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

基于NEMA协议的DALI照明系统研究进展

前言在数字可寻址接口(DALI)镇流器协议被正式纳入国际荧光灯镇流器标准之后,来自美国国家电气制造商协会(NEMA)照明控制分会、镇流器分会、灯具分会和布线装置分会的代表们开始了对一种适用于照明控制装置如墙壁开关、现场开关、占用式传感器和光传感器的附加性DALI协议的开发     

Asynchronous Mappings and Asynchronous Cellular Automata

The aim of this paper is the study of asynchronous automata, a special kind of automata which encode the independency relation between actions and which enable their concurrent execution. These automata, introduced by Zielonka (RAIRO Inform. Theor. Appl.21, 99-135 (1987)), constitute a natural extension of finite automata to the case of asynchronous parallelism. Their behaviour is described by trace languages, subsets of partially commutative monoids. The main result concerning this class of automata states that they accept exactly all recognizable trace languages. In this paper we give new improved constructions of asynchronous automata. In the final part of the paper we present a distributed system of messages with bounded time-stamps based on asynchronous automata.