Synthesis of polydimethylsiloxane‐block‐polystyrene‐block‐polydimethylsiloxane via polysiloxane‐based macroinitiator in supercritical CO2

Polydimethylsiloxane‐block‐polystyrene‐block‐polydimethylsiloxane (PDMS‐b‐PS‐b‐PDMS) was synthesized by the radical polymerization of styrene using a polydimethylsiloxane‐based macroazoinitiator (PDMS MAI) in supercritical CO₂. PDMS MAI was synthesized by reacting hydroxy‐terminated PDMS and 4,4′‐azobis(4‐cyanopentanoyl chloride) (ACPC) having a thermodegradable azo‐linkage at room temperature. The polymerization of styrene initiated by PDMS MAI was investigated in a batch system using supercritical CO₂ as the reaction medium. PDMS MAI was found to behave as a polyazoinitiator for radical block copolymerization of styrene, but not as a surfactant. The response surface methodology was used to design the experiments. The parameters used were pressure, temperature, PDMS MAI concentration and reaction time. These parameters were investigated at three levels (?1, 0 and 1). The dependent variable was taken as the polymerization yield of styrene. PDMS MAI and PDMS‐b‐PS‐b‐PDMS copolymers obtained were characterized by proton nuclear magnetic resonance and infrared spectroscopy. The number‐ and weight‐average molecular weights of block copolymers were determined by gel permeation chromatography. Copyright © 2004 Society of Chemical Industry     

Effects of secondary amyloidosis on arteriovenous hemodialysis fistula outcomes and intradialytic hypotension: a case-control study

Amyloid fibrils can affect vascular structure through deposition and by causing nitric oxide depletion and increase of asymmetric dimethyl arginine. Patients with amyloidosis are prone to development of hypotension. Hypotension may also affect the maturation of arteriovenous fistula (AVF) and may set the stage for formation of thrombosis and fistula failure. Thus, we aimed to evaluate effects of secondary amyloidosis on AVF outcomes and intradialytic hypotension. This is a case‐control study which included 20 hemodialysis patients with amyloidosis and 20 hemodialysis patients without amyloidosis as control group. All patients underwent Doppler ultrasound of AVF. A thorough fistula history and baseline laboratory values along with episodes of intradialytic hypotension and blood pressure measurements were recorded. There was no difference between the groups regarding age, gender, body mass index, presence of comorbidities, hypertension, and drug use. Systolic and diastolic blood pressures were similar (119 ± 28/75 ± 17 and 120 ± 14/75 ± 10 mmHg for patients with and without amyloidosis, respectively). Intradialytic hypotension episodes were also similar. Patients with amyloidosis had significantly lower serum albumin and higher C‐reactive protein values compared to control hemodialysis patients. AVF sites and total number of created fistulas were similar in both groups. Flow rates of current functional AVFs were not different between the groups (1084 ± 875 and 845 ± 466 mL/minute for patients with and without amyloidosis, respectively, p:0.67). Patency duration of first AVF was not different between the groups. Clinical fistula outcomes and rate of intradialytic hypotension episodes were not significantly different between patients with and without secondary systemic amyloidosis.     

The relationship between religious identity and preferred coping strategies: An examination of the relative importance of interpersonal and intrapersonal coping in Muslim and Christian faiths.

Religious affiliation has consistently been shown to help individuals cope with adversity and stressful events. The present paper argues that this proposition is valid for both Christians and Muslims, but that these religious identities foster different types of coping. In accordance with historical, cultural, and psychological accounts, it is proposed that the Christian core self is relatively individualistic, whereas the Muslim core self is oriented more toward the collective. As a consequence, it is hypothesized that when confronted with a stressful life event, Muslims are more likely to adopt interpersonal (collective) coping strategies (such as seeking social support or turning to family members), while Christians are more likely to engage intrapersonal (individualistic) coping mechanisms, such as cognitive restructuring or reframing the event. Evidence from the literature on coping strategies is reviewed and systematized. Evidence lend support to the analysis by indicating that Muslims indeed tend to use an interpersonally oriented (collective) coping style when dealing with adversity, whereas Christians are more likely to employ intrapersonally oriented (individualistic) strategies when facing comparable scenarios. Implications for theory and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of convergence rate in the central limit theorem for theKalman filter

State-space models are used for modeling of many physical and economic processes. An asymptotic distribution theory for the state estimate from a Kalman filter in the absence of the usual Gaussian assumption was presented by Spall and Wall (1984). They proved the central limit theorem for state estimators when the random terms in the model have arbitrary distribution. In this study, some convergence rates in the central limit theorem are given. These convergence rates are used for the development of a nonparametric test of the validity of the model     

Controller area network (CAN) for computer integrated manufacturing systems

Communication acts a central role in computer-integrated manufacturing (CIM). The choice of communication system widely determines the capability and productivity of a factory as a whole. Moreover, in the implementation of CIM systems, the costs associated with the interconnection of the individual CIM components are very important. In CIM, communication is largely used to control programmable manufacturing equipment. Here, the time requirements are high, and error-free data transmission is a necessity. Fieldbuses are special form of local area network dedicated to applications in the field of data acquisition and the control of sensors and actuators in machines or on the factory floor. Many fieldbus standards exist in the market today. Each of them has been invented at different periods by different companies and for different purposes. Controller area network (CAN) is one of the most popular fieldbuses. The highest advantages of CAN are its low cost, abundance of silicon technology, and reliability in networking multiple real-time systems. CAN is a multimaster bus topology and has shown to be very efficient medium for error detection and fault tolerance. CAN's technical specifications are defined in the ISO/OSI network layer spans just two layer of the model. CAN specifies, in many innovative ways, the physical signaling over the media, data formats, timing, error recovery, protocols and arbitration. It does not define the media itself and its connectors, and also the upper layers (usually software) of the model.     

Performance Evaluation of a Real-time Simulation Architecture using Probabilistic Model Checking

The goal of this paper is to show how to use probabilistic model checking techniques in order to achieve quantitative performance evaluation of a real-time distributed simulation. A simulation based on the High Level Architecture (HLA) is modelled as a stochastic process, a Continuous Time Markov Chain (CTMC), using the stochastic algebra PEPA. Next a property representing a performance constraint is evaluated applying Continuous Stochastic Logic CSL formula on the CTMC model using the probabilistic model checker PRISM. Finally a first experiment is made to compare the model with a real case.     

Manufacture of High Performance Carbon Fibers from Precursors of Various Diameters

The effects of fiber diameter on the mechanical properties of PAN-based carbon fibers have been investigated in a series of processing experiments on fibers with different starting filament diameters. The fiber tows, with similar initial mechanical performance, were stretched at high temperatures to produce a large number of fiber types with a wide range of filament diameters. The three starting carbon fibers tows had nominal filament diameters of 5 μm, 6·5 μm, and 10 μm and contained 12000, 6000, and 3000 filaments respectively. These tows were stretched for 5 minutes at 2600^°C with a series of loads of up to 6 kg. For all fiber types and all stretching conditions, substantial increases in Young's moduli were induced, the increases being closely related to the induced extensions. However, it was found that tensile strengths generally decreased if fibers were subjected to high temperatures without significant stretching. On the other hand, the tensile strengths were restored to their original values when greater strains were induced by using higher stresses. Although fibers with a relatively large diameter of 8·3 μm were produced with a modulus of -470GPa and strength of -3·7 GPa, greater improvements in mechanical properties were achieved with smaller diameter fibers. The loads and temperatures involved in these hot stretching experiments were not excessive, and the investigations showed that serious consideration should be given to the feasibility of commercial production of high performance PAN-based carbon fibers by this processing route.     

Models and computational strategies linking physiological response to molecular networks from large-scale data

An important area of research in systems biology involves the analysis and integration of genome-wide functional datasets. In this context, a major goal is the identification of a putative molecular network controlling physiological response from experimental data. With very fragmentary mechanistic information, this is a challenging task. A number of methods have been developed, each one with the potential to address an aspect of the problem. Here, we review some of the most widely used methodologies and report new results in support of the usefulness of modularization and other modelling techniques in identifying components of the molecular networks that are predictive of physiological response. We also discuss how system identification in biology could be approached, using a combination of methodologies that aim to reconstruct the relationship between molecular pathways and physiology at different levels of the organizational complexity of the molecular network.