Heterocyclic polyimides containing siloxane groups in the main chain

BACKGROUND: Among the polymers widely studied for applications in advanced techniques, aromatic polyimides have received considerable attention due to their outstanding thermal stability associated with good electrical and mechanical properties. However, these polymers are usually difficult to process, being insoluble and without a glass transition. To improve the processing characteristics of polyimides, modification of their structure is often achieved by the introduction of flexible linkages in the macromolecular chain or various substituents on the aromatic rings. RESULTS: A series of polyimides and intermediate polyamidic acids were synthesized from aromatic oxadiazole‐diamines and a dianhydride containing a siloxane bridge (? R₂Si? O? SiR₂? ). These polymers exhibit good solubility in certain organic solvents and can be cast into thin and very thin films from their solutions. They exhibit high thermal stability with decomposition being above 440 °C and relatively low glass transition temperatures in the range 160–190 °C. These polymers show strong photoluminescence in the blue spectral region. CONCLUSION: The introduction of oxadiazole rings together with siloxane groups into the chains of aromatic polyimides gives highly thermostable polymers with remarkable solubility and film‐forming ability and that emit blue light, being attractive for applications in micro‐ and nanoelectronics and other related advanced fields. Copyright © 2009 Society of Chemical Industry     

A comparison of higher order auditory processes in younger and older adults.

The authors conducted 3 experiments investigating the effects of aging on higher order auditory processes. They compared younger and older adults with respect to (a) their auditory channel capacity, (b) the extent of their top-down control over auditory gain, and (c) their ability to focus attention on a narrow band of frequencies. To ensure that subclinical cochlear processing deficits in older adults (e.g., higher thresholds, poorer discrimination of frequency and intensity differences) did not limit performance, the authors used only stimuli that were perfectly discriminable by all participants. No age differences were found in any of these experiments, suggesting that some higher order auditory processes (e.g., top-down control over auditory gain, auditory attention) are preserved in normal aging, despite numerous age-related declines in peripheral auditory functionality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contingency management for smoking cessation in adolescent smokers.

This pilot study evaluated the use of contingency management (CM) procedures in combination with cognitive-behavioral therapy (CBT) for smoking cessation in adolescents. Twenty-eight treatment-seeking adolescent smokers participated in a 1-month, school-based smoking cessation program and were randomly assigned to receive either CM with weekly CBT or CBT alone. In the CM+CBT group, biochemical verification of abstinence was obtained twice daily during the first 2 weeks, followed by daily appointments during the 3rd week and once every other day during the 4th week. Participants were monetarily reinforced for abstinence on an escalating magnitude schedule with a reset contingency. At the end of 1 week and 1 month of treatment, abstinence verified using quantitative urine cotinine levels was higher in participants in the CM+CBT group (1 week: 76.7%; 1 month: 53.0%) when compared with the CBT-alone group (1 week: 7.2%; 4 weeks: 0%). These preliminary results provide a strong initial signal supporting the utility of CM techniques for smoking cessation in adolescents and demonstrate the feasibility of implementing such a program in a school setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

LEARNING PRECONDITIONS FOR PLANNING FROM PLAN TRACES AND HTN STRUCTURE

A great challenge in developing planning systems for practical applications is the difficulty of acquiring the domain information needed to guide such systems. This paper describes a way to learn some of that knowledge. More specifically, the following points are discussed. (1) We introduce a theoretical basis for formally defining algorithms that learn preconditions for Hierarchical Task Network (HTN) methods. (2) We describe Candidate Elimination Method Learner ( CaMeL ), a supervised, eager, and incremental learning process for preconditions of HTN methods. We state and prove theorems about CaMeL's soundness, completeness, and convergence properties. (3) We present empirical results about CaMeL's convergence under various conditions. Among other things, CaMeL converges the fastest on the preconditions of the HTN methods that are needed the most often. Thus CaMeL's output can be useful even before it has fully converged.     

Preface: Volume 23, Issue 1

This volume contains the Proceedings of A Tutorial Workshop on Realizability Semantics and Applications. The workshop was associated to the 1999 Federated Logic Conference, held in Trento, Italy, from June 30 to July 1, 1999.There has been recently a reawaking of interest in many aspects of realizability interpretations---especially as regards semantics of type theories for constructive reasoning and semantics of programming languages. As the details of realizability can be quite technical, it seemed appropriate to have a tutorial workshop, connected to the Federated Logic Conference, aimed at offering presentations of the various aspects of realizability and directed to a wide audience, not necessarily only for the experts in the field.The Tutorial Workshop on Realizability Semantics and Applications was proposed to the 1999 Federated Logic Conference, Trento, June 29-July 12, 1999, was accepted, and is organized around several tutorial lectures on history, basic definitions and results, recent applications, connections to category theory and then offers a few contributed research talks of 30 minutes each.The Tutorial Presenters are:

Full-size image

     

Costs of predoctoral clinical psychology internship training in a Canadian health care setting.

Financial pressures on institutional health care in Canada in recent years have led to substantial pressures on institutional psychological services. These pressures have resulted in the elimination or substantial diminution of psychological services in some of these institutions, including the discontinuation of many longstanding psychology internship programs. It is therefore important for psychologists to demonstrate their cost-efficiency in delivering services. However, evidence for this efficiency in the current Canadian context is lacking. This investigation examines the costs and clinical activities of the interns and staff at a major Canadian teaching hospital in order to determine the degree to which the internship is a cost-efficient method of delivering services. The results indicate that there is a small increased cost to having the services delivered through an internship program. The results are viewed as part of a balanced scorecard approach to the evaluation of an internship program. From such a perspective, other factors can be seen as balancing out the slightly increased cost. Also, a number of strategies are outlined for increasing internship cost-efficiency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Safety of absorbable suture for sternal closure after pulmonary or mediastinal resection

The reliability of polyglyconate monofilament (Maxon) suture for sternal closure was tested on 216 consecutive sternotomies, performed on 208 patients in our department from January 1986 to December 1990. The reason of sternotomy was primary lung cancer in 34 cases (16%), lung metastases in 127 (59%), and disorders of the thymus in 55 (25%). Mean age was 38 years (range 3 to 78 years); multiple lung resections were performed in 102 patients (average 7 lesions, range 2 to 30); maximum extent of the operation was pneumonectomy in 2 cases, lobectomy in 53, segmentectomy in 27, and wedge resection in 74. Prior chemotherapy had been administered in 75 cases (35%). A second sternotomy was performed in 8 cases. No cases of sternal dehiscence, sternal infection, or empyema were observed, after a median follow-up of 27 months. Overall perioperative mortality was 0.9% (2/216). Our series demonstrates the safety of polyglyconate monofilament (Maxon) suture for sternal closure. Absorbable sutures appear to be a safe alternative to steel wire closure in patients undergoing extended pulmonary or mediastinal resection.     

More Harvard humbug.

Replies to J. Sonnenfeld's (1982) critique of D. Bramel and R. Friend's (see record 1982-08638-001) article on the studies performed at the Hawthorne plant of Western Electric. Sonnenfeld fails to recognize the unique aspects of Bramel and Friend's reinterpretation of what happened at Hawthorne. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Three-dimensional finite-element analysis of laminated composites

A three-dimensional finite-element analysis treating the mechanical response of thick laminated composite plates in bending is presented. An isoparametric solid element with a cubic displacement expansion in planform and a linear variation through the thickness is used to model each layer of the laminate. The degrees-of-freedom of the element are retained at its boundaries so that interconnections between lamina with different fiber orientations can be made at their interfaces. An incore version of the conjugate gradient technique, which does not have bandwidth restrictions, is used to minimize the total potential energy of the system with the number of iterations to convergence being about one-fifth the total global degrees-of-freedom. Because a three-dimensional analysis is used, the effects of thickness-stretching, transverse shear, extension, and bending deformations are obtained. Comparisons with three-dimensional elasticity solutions are in excellent agreement and show the necessity of having individual elements for each layer when they have different fiber orientations and when the plates are thick.