Search

The contributions postdoctoral scholars make to scientific production are well-documented. Increasingly in the USA, serving as a postdoctoral scholar is an expected component of a scientist's career. A notable feature of the job market for postdoctoral scholars is that it is ad hoc. Social network theory and supporting empirical evidence suggest that personal connections in job searches are beneficial for turnover, satisfaction, and productivity outcomes. This is particularly relevant given the large fraction of foreign postdoctoral scholars, who may naturally be more constrained in their search networks than their US-based counterparts. Using the Sigma Xi Scientific Research Society's data on postdoctoral scholars in the USA, we explore the relationship between job search methods and these outcomes, focusing on the differences in outcomes between domestic and foreign postdoctoral scholars. We find suggestive evidence of weaker networks for foreign postdoctoral scholars, who more often resort to 'impersonal' searches. The resulting difference in job match quality is related to differences in turnover, satisfaction, and productivity, which suggests that public policies to facilitate the job search of postdoctoral scholars (foreign ones especially) may yield substantial benefits. [ABSTRACT FROM AUTHOR]

The article examines the passive decay heat removal (DHR) in a Generation IV (GEN IV) direct-cycle gas-cooled fast reactor (GFR). It explores the approach taken for the high-temperature thermal gas-cooled reactors (HTRs) for passive DHR. Furthermore, it analyzes the conceptual design for DHR's autonomous systems.

Background/Aims: The current standard of care to perform an anterior chamber paracentesis involves the use of a multipurpose market needle and syringe. The use of standard needles for this purpose may result in injury to the patient due to increased force with insertion and increased globe displacement during the procedure. This research investigates the current market needle characteristics and the impact of each needle characteristic on force. Methods: Several comparative trials were conducted to evaluate the needles. Needle characteristics of interest were gauge, primary bevel angle, number of bevels in the lancet, and needle hub geometry. Measurements of corneal insertion forces were made using a synthetic thermoplastic polyurethane medium, and bovine and porcine models. Needle safety was investigated with corneal abrasion experiments. Results: Reduced insertion force was observed with lower lancet primary angle. There was no difference based on the number of bevels in the lancet. Rounded hub geometry had minimal distribution to the corneal epithelium. Conclusions: Needle characteristics impact the force needed for needle insertion into the tissue. Since higher force can lead to increased risk and less efficiency during the procedure, reducing this force may improve the outcomes of the procedure. Needle entry can be reduced by designing an improved needle that includes a lower gauge and reduced primary angle of the lancet. [ABSTRACT FROM AUTHOR]

The application of artificial intelligence techniques for performance optimization of the fuel lean gas reburn (FLGR) system is investigated. A multilayer, feedforward artificial neural network is applied to model static non-linear relationships between the distribution of injected natural gas into the upper region of the furnace of a coal-fired boiler and the corresponding oxides of nitrogen (NO[subx]) emissions exiting the furnace. Based on this model, optimal distributions of injected gas are determined such that the largest NO[subx] reduction is achieved for each value of total injected gas. This optimization is accomplished through the development of a new optimization method based on neural networks. This new optimal control algorithm, which can be used as an alternative generic tool for solving multidimensional nonlinear constrained optimization problems, is described and its results are successfully validated against an off-the-shelf tool for solving mathematical programming problems. Encouraging results obtained using plant data from one of Commonwealth Edison's coal-fired electric power plants demonstrate the feasibility of the overall approach. Preliminary results show that the use of this intelligent controller will also enable the determination of the most cost-effective operating conditions of the FLGR system by considering, along with the optimal distribution of the injected gas, the cost differential between natural gas and coal and the open-market price of NO[subx] emission credits. Further study, however, is necessary, including the construction of a more comprehensive database, needed to develop high-fidelity process models and...