Publications

A simple molding process carried out within the confines of a closed mold has been used for the preparation of porous polymer monoliths. The polymerization is carried out using a mixture of monomers, porogenic solvent, and free-radical initiator under conditions that afford macroporous materials with through-pores or channels large enough to provide the high flow characteristics required for their applications. The versatility of the preparation technique is demonstrated by its use with both hydrophobic and hydrophilic monomers such as styrene, (chloromethyl)styrene, glycidyl methacrylate, alkyl methacrylates, 2-(acrylamido)-2-methyl-1-propanesulfonic acid, acrylic acid, and acrylamide. Techniques have been developed that allow fine control of the porous properties of the polymers. These, in turn, determine the hydrodynamic properties of the devices that contain the molded media. Since all of the mobile phase must flow through the monolith, the mass transport within the molded material is accelerated considerably by convection, and the monolithic devices perform well even at much higher flow rates than those used with packed columns. This is particularly important for the chromatographic separations of large molecules such as proteins, for which diffusion is a serious problem that significantly slows down the separation processes. Similarly, this convection provides faster transport of substrates to active sites with immobilized enzymes, and it increases significantly the apparent activity of the conjugate. The molded separation media have been used for the chromatographic separation of biological compounds using modes such as reversed-phase, hydrophobic interaction, and ion-exchange chromatography, synthetic polymers and oligomers in reversed-phase and precipitation−redissolution mode, for electrochromatography, enzyme immobilization, and molecular recognition, and in advanced detection systems. Grafting of pores with selected polymer chains has led to "smart" materials that quickly respond to external stimuli and change the permeability and/or polarity of the monolith.

This paper describes the BID Data Suite, a collection of hardware, software and design patterns that enable fast, large-scale data mining at very low cost. By co-designing all of these elements we achieve single-machine performance levels that equal or exceed reported cluster implementations for common benchmark problems. A key design criterion is rapid exploration of models, hence the system is interactive and primarily single-user. The elements of the suite are: (i) the data engine, a hardware design pattern that balances storage, CPU and GPU acceleration for typical data mining workloads, (ii) BIDMat, an interactive matrix library that integrates CPU and GPU acceleration and novel computational kernels (iii), BIDMach, a machine learning system that includes very efficient model optimizers, (iv) Butterfly mixing, a communication strategy that hides the latency of frequent model updates needed by fast optimizers and (v) Design patterns to improve performance of iterative update algorithms. We present several benchmark problems to show how the above elements combine to yield multiple orders-of-magnitude improvements for each problem.

Major organizational changes among hospitals, like system affiliation, merger, and closure, would seem to offer substantial opportunities for hospitals and health systems to be strategic in the local reconfiguration of health services. This report presents the results of a unique survey on what happened to hospitals after mergers occurring between 1983 and 1988, inclusive. Building on an ongoing verification process of the American Hospital Association, surviving institutions from all 74 mergers that occurred during the study frame were surveyed in the fall of 1991. Responses were received from 60 of the 74 mergers (81%), regarding the primary, postmerger use of the hospitals involved. Topics surveyed included the premerger competition between the hospitals and in their environment, and what happened to the hospitals after their mergers. Mergers frequently served to convert acute, inpatient capacity to other functions, with less than half of acquired hospitals continuing acute services after merger. In the context of health care reform, mergers may offer an expeditious way locally to restructure health services. Evidence on the postmerger uses of hospitals and about the reasons given for merger suggests that mergers may reflect two general strategies: elimination of direct acute competitors or expansion of acute care networks.

Keywords INSTITUTION OF CIVIL ENGINEERS, ICE RESPONSIBILITY, CIVIL ENGINEERING, PROBLEMS, SUBCONTRACTS, CONTRACTORS, PAYMENTS, NOMINATED, WORKS, CONDITIONS, PLACING, DAMAGES, SUBCONTRACTORS, SUPPLIERS, CONTRACTS, RETENTION, LIABILITY... Show All

We propose and analyze a proportional share resource allocation algorithm for realizing real-time performance in time-shared operating systems. Processes are assigned a weight which determines a share (percentage) of the resource they are to receive. The resource is then allocated in discrete-sized time quanta in such a manner that each process makes progress at a precise, uniform rate. Proportional share allocation algorithms are of interest because: they provide a natural means of seamlessly integrating real and non-real-time processing; they are easy to implement; they provide a simple and effective means of precisely controlling the real-time performance of a process; and they provide a natural means of policing so that processes that use more of a resource than they request have no ill-effect on well-behaved processes. We analyze our algorithm in the context of an idealized system in which a resource is assumed to be granted in arbitrarily small intervals of time and show that our algorithm guarantees that the difference between the service time that a process should receive and the service time it actually receives is optimally bounded by the size of a time quantum. In addition, the algorithm provides support for dynamic operations, such as processes joining or leaving the competition, and for both fractional and non-uniform time quanta. As a proof of concept we have implemented a prototype of a CPU scheduler under FreeBSD. The experimental results shows that our implementation performs within the theoretical bounds and hence supports real-time execution in a general purpose operating system.

Unusual bonding: A ligand system that promotes formation of a rare μ-η1:η1 acetonitrile-bridged dicopper(I) complex (see picture) has been developed. The acetonitrile ligand is involved in a three-center two-electron bond supported by a cuprophilic interaction. The labile acetonitrile ligand can be substituted with xylyl isocyanide or CO.

In this letter we report experimental observation of hyperchaotic attractors in open and closed chains of Chua's circuits.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of ethane oxidation on vanadium oxideS. Ted. Oyama, Ann M. Middlebrook, and Gabor A. SomorjaiCite this: J. Phys. Chem. 1990, 94, 12, 5029–5033Publication Date (Print):June 1, 1990Publication History Published online1 May 2002Published inissue 1 June 1990https://doi.org/10.1021/j100375a049RIGHTS & PERMISSIONSArticle Views533Altmetric-Citations76LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (584 KB) Get e-Alerts