Primary repair of colorectal injuries in childhood

A retrospective survey of 44 children with colorectal perforating injuries secondary to shrapnel and high velocity bullets is presented. Seven patients had the injury limited to the colon or rectum. All patients were operated upon within 7 hr from the their colonic wounds and 20 underwent a colostomy. Five of the patients repaired primarily had their injuries to the left side of the colon or rectum. None of the patients undergoing primary repair suffered from an anastomotic leak. The mortality rate after primary repair was 16.6% and after colostomy 10%. The mortality was significantly different in the group of patients who had additional injuries where a colostomy procedure was associated with a lower mortality rate (11% versus 21%). Shock on admission and during operation affected survival adversely in all patients. The average hospital stay of survivors was 24 days with "primary repair" and 36 days with "colostomy."     

Determinants of e-consumer productivity in product retrieval on a commercial website: An experimental approach

This article investigates what determines e-consumer productivity, in the specific case of product retrieval, on a commercial website. With a 2 × 2 × 2 factorial design on 292 participants, an online experiment reveals that productivity in product retrieval (measured in terms of effectiveness, efficiency, and time) relates to website design (e.g., abstraction level of labels, animation), user characteristics (e.g., Internet experience, product category familiarity, cognitive absorption), and situational characteristics (e.g., task nature). The results also confirm interactive effects among the type of strategy used, the nature of the task, and the website design. These findings have notable implications for both research and practice.     

Fault-tolerant scheduling on parallel systems with non-memoryless failure distributions

As large parallel systems increase in size and complexity, failures are inevitable and exhibit complex space and time dynamics. Most often, in real systems, failure rates are increasing or decreasing over time. Considering non-memoryless failure distributions, we study a bi-objective scheduling problem of optimizing application makespan and reliability. In particular, we determine whether one can optimize both makespan and reliability simultaneously, or whether one metric must be degraded in order to improve the other. We also devise scheduling algorithms for achieving (approximately) optimal makespan or reliability. When failure rates decrease, we prove that makespan and reliability are opposing metrics. In contrast, when failure rates increase, we prove that one can optimize both makespan and reliability simultaneously. Moreover, we show that the largest processing time (LPT) list scheduling algorithm achieves good performance when processors are of uniform speed. The implications of our findings are the accelerated completion and improved reliability of parallel jobs executed across large distributed systems. Finally, we conduct simulations to investigate the impact of failures on the performance, which is done using an actual application of biological sequence comparison.     

Optimized design of a digital I/Q demodulator suitable for adaptive pre-distortion of 3rd generation base station PAs

This article presents an optimized design of a high-speed digital I/Q demodulator intended for the implementation of the feedback path of an adaptive base band digital pre-distorter (DPD). Indeed, the optimization of the DPD linearization capability, in terms of correction bandwidth and nonlinearity effects minimization, is directly related to the accuracy and speed of the I/Q demodulator. In this work, a digital I/Q demodulator is designed, optimized and implemented in a Xilinx FPGA device. This allowed for high-speed processing of about 200 MHz with a substantial reduction in the FPGA used gates.     

Microstructure characterization and tensile properties of direct squeeze cast and gravity die cast 2017A wrought Al alloy

Squeeze casting is a pressurized solidification process wherein finished components can be produced in a single process from molten metal to solid utilizing re-useable die tools. This one activates different physical processes which have metallurgical repercussions on the cast material structure. Desirable features of both casting and forging are combined in this hybrid method. 2017A aluminium alloy, conventionally used for wrought products, has been successfully cast using direct squeeze casting. Squeeze casting with an applied pressure removes the defects observed in gravity die cast samples. Tensile properties and microstructures are investigated. The results show that the finer microstructure was achieved through the squeeze casting. Furthermore, higher pressures improved the fracture properties and decreased the percentage of porosity of the cast alloy. The ultimate tensile strength, the yield strength and the elongation of the squeezed cast samples improved when the squeeze pressure increased.     

Brain and Liver Headspace Aldehyde Concentration Following Dietary Supplementation with n‐3 Polyunsaturated Fatty Acids

Reactive oxygen species react with unsaturated fatty acids to form a variety of metabolites including aldehydes. Many aldehydes are volatile enough to be detected in headspace gases of blood or cultured cells and in exhaled breath, in particular propanal and hexanal which are derived from omega‐3 and omega‐6 polyunsaturated fatty acids, respectively. Aldehydes are therefore potential non‐invasive biomarkers of oxidative stress and of various diseases in which oxidative stress is thought to play a role including cancer, cardiovascular disease and diabetes. It is unclear, however, how changes in the abundance of the fatty acid precursors, for example by altered dietary intake, affect aldehyde concentrations. We therefore fed male Wistar rats diets supplemented with either palm oil or a combination of palm oil plus an n‐3 fatty acid (alpha‐linolenic, eicosapentaenoic, or docosahexaenoic acids) for 4 weeks. Fatty acid analysis revealed large changes in the abundance of both n‐3 and n‐6 fatty acids in the liver with smaller changes observed in the brain. Despite the altered fatty acid abundance, headspace concentrations of C1–C8 aldehydes, and tissue concentrations of thiobarbituric acid reactive substances, did not differ between the 4 dietary groups. Our data suggest that tissue aldehyde concentrations are independent of fatty acid abundance, and further support their use as volatile biomarkers of oxidative stress.     

HYDRODYNAMIC AND ELASTOHYDRODYNAMIC STUDIES OF A CYLINDRICAL JOURNAL BEARING

In this article, the effect of the bearing elastic deformation on the performance characteristics of a cylindrical journal bearing is analyzed. The variety of simulation models covers hydrodynamic (HD) and elastohydrodynamic (EHD) lubrication theories. The Reynolds equations governing the flow in the clearance space of the journal bearing are obtained by considering the effect of mass transfer across the fluid film. The finite element method with an iteration scheme was employed to solve both the Reynolds equation and the three-dimensional elasticity equation representing the displacement field in the bearing shell. The converged solutions for the lubricant flow and elastic deformation vector are obtained. Dynamic characteristics of the journal bearing are computed for HD and EHD theories. Numerical simulation results show that the flexibility of bearing liner has a significant influence on the performance of a cylindrical journal bearing. Indeed, the elastic deformations of the bearing liner extend the pressure area in the bearing and increase the minimum film thickness. Although, dynamic coefficient, load capacity and attitude angle decrease.     

Formation of assimilable organic carbon (AOC) and specific natural organic matter (NOM) fractions during ozonation of phytoplankton

Ozonation of natural surface water increases the concentration of oxygen-containing low molecular weight compounds. Many of these compounds support microbiological growth and as such are termed assimilable organic carbon (AOC). Phytoplankton can contribute substantially to the organic carbon load when surface water is used as source for drinking water treatment. We have investigated dissolved organic carbon (DOC) formation from the ozonation of a pure culture of Scenedesmus vacuolatus under defined laboratory conditions, using a combination of DOC fractionation, analysis of selected organic acids, aldehydes and ketones, and an AOC bioassay. Ozonation of algae caused a substantial increase in the concentration of DOC and AOC, notably nearly instantaneously upon exposure to ozone. As a result of ozone exposure the algal cells shrunk, without disintegrating entirely, suggesting that DOC from the cell cytoplasm leaked through compromised cell membranes. We have further illustrated that the specific composition of newly formed AOC (as concentration of organic acids, aldehydes and ketones) in ozonated lake water differed in the presence and absence of additional algal biomass. It is therefore conceivable that strategies for the removal of phytoplankton before pre-ozonation should be considered during the design of drinking water treatment installations, particularly when surface water is used.     

ACOUSTIC ANALYSIS OF HYDRODYNAMIC AND ELASTO-HYDRODYNAMIC OIL LUBRICATED JOURNAL BEARINGS

The purpose of the present paper is to investigate the effect of elastic deformation of bearing liner on the acoustic behavior of oil lubricated journal bearings.Analysis is performed for hydrodynamic(HD) and elasto-hydrodynamic (EHD) lubrications.Dynamic behavior and acoustical properties are investigated through an analysis of pressure fluctuation calculated from the Reynolds equation governing the flow in the clearance space of the journal bearing.This is solved numerically using the finite difference method with the successive over relaxation technique.In elasto-hydrodynamic lubrication,the finite element method with in iteration scheme is adopted to solve both Reynolds equation and the three-dimensional elasticity equation representing the displacement field in the bearing shell.The results show that the sound pressure level of the bearing is markedly influenced by the flexibility of the bearing liner,the viscosity of lubricant and the load applied to journal.HD analysis shows that the journal centre’s orbit,from a disturbed position,converges to the static equilibrium position faster than EHD lubrication.The results of the present paper could aid in the design of low-noise rotor-bearing systems supported by oil lubricated journal bearings.