Successful use of a bivalirudin treatment protocol to prevent extracorporeal thrombosis in ambulatory hemodialysis patients with heparin‐induced thrombocytopenia

Heparin‐induced thrombocytopenia (HIT) is an uncommon problem in hemodialysis (HD) patients. There have been a few reports on the use of lepirudin, argatroban, or danaparoid in the management of extracorporeal thrombosis (ECT) during dialysis in these patients, because heparin is contraindicated. Here, we report the first long‐term use of bivalirudin to prevent ECT. Our study was conducted at Fahd Bin Jassim Kidney Center in Doha, Qatar. All patients diagnosed with HIT were included. A bivalirudin treatment protocol was developed with the initial dosage and dosage adjustments based on the value of activated partial thromboplastin time (aPTT), the risk of bleeding, and the recurrence of ECT. Eight patients were positive for HIT AB. Among them, three were excluded: two due to the use of warfarin for atrial fibrillation and one due to a negative repeat HIT AB test with no ECT. Five patients who were positive for HIT AB and experienced recurrent ECT events during dialysis were included. These patients were monitored while on bivalirudin protocol for a mean of 4.6 ± 2 months, during which they received a mean number of HD treatments of 66 ± 24. There were no bleeding events or adverse reactions related to bivalirudin during the study. Here, we report the first long‐term successful use of a bivalirudin protocol to prevent ECT in ambulatory HD patients with HIT. This protocol allowed for a simple dosing initiation with easy adjustment based on weight, aPTT, and recurrence of ECT events. The protocol provided excellent safety.     

Changes in biochemical,hemodynamic, and dialysis adherence parameters in hemodialysis patients during Ramadan

This paper aimed to study the effect of Ramadan fasting on biochemical and clinical parameters and compliance for dialysis. A prospective multicenter observational cross‐sectional study comparing fasting with a non‐fasting stable adult hemodialysis patients for demographic and biochemical parameters, compliance with dialysis, inter‐dialytic weight gain, pre‐ and post‐blood pressure, and frequency of intradialytic hypotensive episodes was carried out. Six hundred thirty‐five patients, of whom 64.1% fasted, were studied. The fasters were younger (53.3 ± 16.2 vs. 58.4 ± 16.1 years; P = 0.001) but had similar duration on dialysis (P = 0.35). More fasters worked (22.0% vs. 14.6%; P = 0.001) and missed dialysis sessions during Ramadan. No differences were noted between groups in sex, diabetic status, or dialysis shift or day. There were no differences in the pre‐ and post‐dialysis blood pressure; serum potassium, albumin or weight gain; diabetic status; sex; and dialysis shift time or days. However, serum phosphorous was significantly higher in the fasting group (2.78 ± 1.8 vs. 2.45 ± 1.6 mmol/L; P = 0.045). There were no intragroup differences in any of the parameters studied when comparing the findings during Ramadan with those in the month before Ramadan. Fasters were significantly younger and more likely to be working, to miss dialysis sessions, and to have higher serum phosphorous levels. No other differences were observed.     

Dark-spot detection from SAR intensity imagery with spatial density thresholding for oil-spill monitoring

Dark-spot detection is a critical and fundamental step in marine oil-spill detection and monitoring. In this paper, a novel approach for automated dark-spot detection using synthetic aperture radar (SAR) intensity imagery is presented. The key to the approach is making use of a spatial density feature to differentiate between dark spots and the background. A detection window is passed through the entire SAR image. First, intensity threshold segmentation is applied to each window. Pixels with intensities below the threshold are regarded as potential dark-spot pixels while the others are potential background pixels. Second, the density of potential background pixels is estimated using kernel density estimation within each window. Pixels with densities below a certain threshold are the real dark-spot pixels. Third, an area threshold and a contrast threshold are used to eliminate any remaining false targets. In the last step, the individual detection results are mosaicked to produce the final result. The proposed approach was tested on 60 RADARSAT-1 ScanSAR intensity images which contain verified oil-spill anomalies. The same parameters were used in all tests. For the overall dataset, the average of commission error, omission error, and average difference were 7.0%, 6.1%, and 0.4 pixels, respectively. The average number of false alarms was 0.5 per unit image and the average computational time for a detection window was 1.2 s using a PC-based MATLAB platform. Our experimental results demonstrate that the proposed approach is fast, robust and effective.     

The OTIS hyper hexa-cell optoelectronic architecture

Optical transpose interconnection system (OTIS) is an optoelectronic architecture that promises to be a great choice for future-generation parallel systems. OTIS combines the advantages of electronic and optical links, where electronic links are used for short distances which require low material cost, and optical links are used for long distances which provide high speed network with low power consumption. Taking into account the advantageous characteristics of OTIS and based on the attractive properties of hyper hexa-cell (HHC) interconnection topology from low diameter and good minimum node degree, this paper introduces a new optoelectronic architecture referred to as OTIS hyper hexa-cell (OHHC). This paper also provides an evaluation and a comparison of the new topology with OTIS-mesh in terms of the following topological properties: size, diameter, maximum and minimum node degree, bisection width, total cost and optical cost. The results of this study proved the excellence of the proposed OHHC over OTIS-mesh in terms of diameter, minimum node degree, bisection width, and optical cost.     

Computer Simulation for the Evaluation of the IBM-SNA Congestion Management Method on GULFNET

The work presented in this article aims at using an available computer simulation package for the evaluation of the operation of the IBM-SNA-VRPC congestion management method on the present state of GULFNET, and a future design of the network that includes more nodes and provides higher reliability.     

Synthesis of energy-induced waste minimization networks (EIWAMINs) for simultaneous waste reduction and heat integration

 This article introduces a process synthesis methodology for identifying cost-effective Energy-Induced Waste Minimization Networks (EIWAMINs). The synthesis methodology is targeted toward retrofit designs for an existing plant or site where environmental emissions (aqueous or gaseous) must be reduced. This approach uses heat-induced separation units that separate mass via a phase change (condensers, dryers, crystallizers, evaporators, etc.) and heat exchangers to simultaneously address waste minimization and heat integration within a large plant or site. While heat-induced separators may be employed for optimal waste separation and allocation (via a phase change), heat exchange equipment (e.g. heaters, coolers, chillers, etc.) may be employed to improve the thermodynamics of existing unit operations. In addition, pressurization/depressurization devices (compressors, turbines, etc.) are also employed to enhance the effectiveness of the heat-induced separators. The problem is tackled via two mathematical formulations which are mixed-integer non-linear programs (MINLPs). The mathematical formulations are combined to identify the most cost-effective design(s) that simultaneously addresses the plant waste minimization and heat integration tasks. Linearization techniques and graphical insights are incorporated to simplify the mathematical formulation of the problem. A case study is provided to highlight the features of this design procedure and its economic merits against several alternative designs. Received: 19 November 1998 / Accepted: 21 January 1999     

Modification of rheological and filtration characteristics of water‐based mud for drilling oil and gas wells using green SiO2 @ZnO@Xanthan nanocomposite

In this study, a green, simple and economical approach was used to synthesise the SiO₂ @ZnO@Xanthan nanocomposite (NC) to modify the rheological and filtration characteristics of the water‐based drilling mud. The green synthesised NCs were identified using scanning electron microscopy, energy dispersive X‐ray spectroscopy, elemental mapping, X‐ray diffraction and UV–Vis analytical techniques. Additionally, the effect of SiO₂ @ZnO@Xanthan NCs on the filtration and rheological properties of mud including apparent viscosity, plastic viscosity, yield point, gel strength, mud cake and fluid loss was investigated. The obtained results confirmed that the synthesised NCs effectively improved the rheological properties of drilling mud, and considerably decreased its fluid loss and filter cake by about 54 and 92.5%, respectively. The results highly recommend the SiO₂ @ZnO@Xanthan NC as an excellent additive to improve the rheological properties, and reduce the fluid loss and the filter cake of the drilling mud.Inspec keywords: X‐ray diffraction, scanning electron microscopy, nanofabrication, additives, nanocomposites, X‐ray chemical analysis, drilling (geotechnical), yield point, rheology, filtration, industrial economics, silicon compounds, zinc compounds, ultraviolet spectra, visible spectra, nanofluidics, gelsOther keywords: rheological properties, fluid loss, drilling mud, filtration characteristics, water‐based mud, green approach, economical approach, X‐ray spectroscopy, mud cake, apparent viscosity, oil‐gas wells, nanocomposite synthesis, scanning electron microscopy, energy dispersive X‐ray spectroscopy, elemental mapping, X‐ray diffraction, Uv–Vis spectroscopy, plastic viscosity, yield point, gel strength, additive, SiO₂ , ZnO     

Four wheel steering control by fuzzy approach

This study introduces a fuzzy four-wheel steering control design method for automotive vehicles. After the analysis of some stability aspects of the vehicle lateral motion, including front steering angle variations, the representation of vehicle nonlinear model by Takagi-Sugeno (T-S) fuzzy model is presented. Next, based on the fuzzy model, a fuzzy controller is developed to improve the stability of the vehicle. Sufficient conditions for stability and stabilization of the T-S fuzzy model using fuzzy feedback controllers is given. To demonstrate the effectiveness of the proposed fuzzy controller, simulation results are given showing the performance improvements of the vehicle in terms of the stability and the maneuverability in critical situations.     

Monitoring of a pharmaceutical nanomilling process using grating light reflection spectroscopy

An optical diagnostic method, grating light reflection spectroscopy (GLRS), has been demonstrated for the in situ monitoring of properties of heterogeneous matrices in industrial processes. The technique is based on measurements near the critical points of intensity and phase in waves reflected from a transmission diffraction grating in contact with a diagnostic sample. The features contained in the reflection spectrum near these thresholds allow for the simultaneous determination of the real and imaginary parts of the dielectric function of the sample. Using these data, the milling progress of highly concentrated fluid suspensions is observed as the material is milled from approximately 40 mm to 160 nm in diameter. A theoretical model that closely resembles experimentally determined spectra was constructed and applied in combination with principal components analysis (PCA) to demonstrate that GLRS can be used to closely monitor changes in the mean particle size of the nanomilled drug product.     

Effect of Prandtl number on the entropy profile across shock waves

Summary The effect of the Prandtl number on the variation of entropy across shock waves is calculated, using the Navier-Stokes equations for the gas phase. The resulting system of three ordinary nonlinear differential equations is reduced to a system of two autonomous nonlinear differential equations, which are solved exactly. This solution, is obtained formally by assuming that the Prandtl number is equal to 3/4. A comparison of the behavior of entropy across shock waves for different values of Prandtl number is given.