ESTIMATION OF VAPOR PRESSURES OF ORGANIC NITROGEN AND SULFUR COMPOUNDS BY A GROUP-CONTRIBUTION METHOD

The group-contribution method for vapor pressures of hydrocarbons and organic compounds containing nitrogen or sulfur, based on the kinetic theory of fluids, is revised and extended to include new groups containing nitrogen or sulfur. Good representation is obtained for vapor pressure data in the region 1.30-270 kPa. The method may be used to estimate vapor pressures and enthalpies of vaporization for those organic fluids containing nitrogen or sulfur, where no experimental data are available.     

CU++: an object oriented framework for computational fluid dynamics applications using graphics processing units

The application of graphics processing units (GPU) to solve partial differential equations is gaining popularity with the advent of improved computer hardware. Various lower level interfaces exist that allow the user to access GPU specific functions. One such interface is NVIDIA’s Compute Unified Device Architecture (CUDA) library. However, porting existing codes to run on the GPU requires the user to write kernels that execute on multiple cores, in the form of Single Instruction Multiple Data (SIMD). In the present work, a higher level framework, termed CU++, has been developed that uses object oriented programming techniques available in C++ such as polymorphism, operator overloading, and template meta programming. Using this approach, CUDA kernels can be generated automatically during compile time. Briefly, CU++ allows a code developer with just C/C++ knowledge to write computer programs that will execute on the GPU without any knowledge of specific programming techniques in CUDA. This approach is tremendously beneficial for Computational Fluid Dynamics (CFD) code development because it mitigates the necessity of creating hundreds of GPU kernels for various purposes. In its current form, CU++ provides a framework for parallel array arithmetic, simplified data structures to interface with the GPU, and smart array indexing. An implementation of heterogeneous parallelism, i.e., utilizing multiple GPUs to simultaneously process a partitioned grid system with communication at the interfaces using Message Passing Interface (MPI) has been developed and tested.     

On the Evaluation of the Elastic Modulus of Soft Materials Using Beams with Unknown Initial Curvature

A non‐linear optimization procedure is established to determine the elastic modulus of slender, soft materials using beams with unknown initial curvature in the presence of large rotations. Specifically, the deflection of clamped‐free beams under self‐weight – measured at different orientations with respect to gravity – is used to determine the modulus of elasticity and the intrinsic curvature in the unloaded state. The approach is validated with experiments on a number of different materials – steel, polyetherimide, rubber and pig skin. Because the loading is limited to self‐weight, the strain levels attained in these tests are small enough to assume a linear elastic material behaviour. This non‐destructive methodology is also applicable to engineered tissues and extremely delicate materials in order to obtain a quick estimate of the material's elastic modulus.     

Organic thin film transistors: Materials,processes and devices

For the past ten years, organic materials have been extensively investigated as an electronic material for thin film transistor (TFT) devices. Organic materials offer strong promise in terms of properties, processing and cost effectiveness and they can be used in flat panel displays, imagers, smart cards, inventory tags and large area electronic applications. In this review, we summarize the current status of the organic thin film transistors including substrate materials, electrodes, semiconducting and dielectric layers; organic thin film preparation methods; morphological studies for organic thin films; electrical characterization of gate dielectric layers and semiconducting active layers; and characterization of the OTFTs. Future prospects and investigations required to improve the OTFT performance are also given. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Infections Controlling exit site infections: Does it decrease the incidence of catheter‐related bacteremia in children on hemodialysis?

The most common complication of tunneled‐cuffed hemodialysis catheters is catheter‐related bacteremia (CRB), which contributes to patient morbidity and loss of vascular access. Gram positive microorganisms are the most common etiologic agents; coagulase negative staphylococcus and corynebacterium species are the two most prevalent strains in our center. These are the common inhabitants of skin flora, suggesting that infection of catheters occur through the exit site. The Biopatch is a chlorhexidine impregnated dressing designed to keep the exit site from colonization with skin flora. This may decrease the incidence of CRB due to organisms from the skin. Objective:  To investigate whether the application of the biopatch at the exit site has any effect on the incidence and the etiology of CRB. Methods:  Chart review of 63 pediatric chronic hemodialysis patients who were dialysed between January 1999 and December 2003 was performed. The mean age at start of hemodialysis was 13.9 ± 4.6 years. The pre‐Biopatch era started in January 1999 till the end of June 2001, and the Biopatch era started in July 2001 to December 2003. Biopatch was applied at the beginning of every dialysis week after Betadine cleansing of the exit site, which was then covered with a transparent dressing. In the pre‐Biopatch era, the exit site was cleansed with Betadine at every dialysis session and then covered with a transparent dressing. Results:  The use of the Biopatch at the exit site caused a significant decrease in the exit site infections. However, contrary to what was expected, there was no decrease in the incidence of CRB.  

     

Clad-modified fiber-optic magnetic field sensing characteristics of anion-doped bismuth manganite nanopowders

Journal of Materials Science: Materials in Electronics - It has been reported that magnetoelectric multiferroics are beneficial to magnetic field sensor applications and optoelectronic devices. The...     

Influence of infection on patent ductus arteriosus and chronic lung disease in premature infants weighing 1000 grams or less

OBJECTIVES: To test the hypotheses that (1) infection increases ductal dilatory prostaglandins and inflammatory mediators that may influence the closure of a patent ductus arteriosus (PDA), increasing the incidence of late episodes of PDA (after 7 days) and the rate of closure failures, and (2) the concurrence of PDA and infection increases the risk of chronic lung disease (CLD). METHODS: One hundred fourteen premature infants (birth weight, 500 to 1000 gm) were prospectively assessed for PDA and infection. Serum levels of 6-ketoprostaglandin F1 alpha and tumor necrosis factor alpha were measured routinely in all infants and when PDA or infection was present. Multivariate assessment of risk factors for PDA closure failure and for CLD was done by logistic regression, and expressed as an odds ratio and as 95% confidence intervals. RESULTS: Late PDA episodes were more frequent in infants with infection than in those without infection. A temporally related infection (<5 days between both diagnoses) was associated with an increased risk of PDA closure failure (odds ratio, 19.1 (confidence interval, 4 to 90)). In addition to birth weight and the severity of initial respiratory failure, PDA and infection increased the risk of CLD (odds ratio, 11.7 (confidence interval, 1.7 to 81) for PDA; odds ration, 3.1 (confidence interval, 1 to 11) for infection). Furthermore, when both factors were temporally related, they further increased the risk of CLD (odds ratio, 29.6 (confidence interval, 4.5 to >100)). Infants with infection and those with PDA had higher levels of 6-ketoprostaglandin F1 alpha than did control subjects. Levels of tumor necrosis factor alpha were also elevated in infants with infection and in those with late PDA. CONCLUSIONS: Infection adversely influences PDA outcome by increasing the risk of late ductal reopening and PDA closure failures. Increased levels of prostaglandins and tumor necrosis factor alpha in infants with infection may explain the poor PDA outcome. The concurrence of PDA and infection potentiates their negative effects on the risk of CLD.     

Area and Power Reduction of Embedded DSP Systems using Instruction Compression and Re-configurable Encoding

In embedded control applications, system cost and power/energy consumption are key considerations. In such applications, program memory forms a significant part of the chip area. Hence reducing code size reduces the system cost significantly. A significant part of the total power is consumed in fetching instructions from the program memory. Hence reducing instruction fetch power has been a key target for reducing power consumption. To reduce the cost and power consumption, embedded systems in these applications use application specific processors that are fine tuned to provide better solutions in terms of code density, and power consumption. Further fine tuning to suit each particular application in the targeted class can be achieved through reconfigurable architectures. In this paper, we propose a reconfiguration mechanism, called Instruction Re-map Table, to re-map the instructions to shorter length code words. Using this mechanism, frequently used set of instructions can be compressed. This reduces code size and hence the cost. Secondly, we use the same mechanism to target power reduction by encoding frequently used instruction sequences to Gray codes. Such encodings, along with instruction compression, reduce the instruction fetch power. We enhance Texas Instruments DSP core TMS320C27x to incorporate this mechanism and evaluate the improvements on code size and instruction fetch energy using real life embedded control application programs as benchmarks. Our scheme reduces the code size by over 10% and the energy consumed by over 40%. *A preliminary version of this paper has appeared in the International Conference on Computer Aided Design (ICCAD-2001), San Jose, CA, November 2001.     

Dynamic crack-tip stresses under stress wave loading —A comparison of theory and experiment

The characterization of the electromagnetic stress wave generator is described. The method of caustics applied to birefringent materials is examined in detail in order to explain the lack of double caustics in Homalite-100. The accuracy of the method of caustics is demonstrated experimentally by using two loading configurations and comparing the results with the theoretical analysis of Freund [1].

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Résumé On décrit les caractéristiques d'un générateur électromagnétique d'ondes de contrainte. On examine dans le détail la méthode des caustiques appliquées à des matériaux biréfringeants en vue d'expliquer l'absence de caustique constatée dans l'Homalite 100. On démontre de manière expérimentale la précision de la méthode des caustiques en utilisant deux configurations de charge et en comparant les résultats avec l'analyse théorique effectuée par Freund.