Recognition and management of catheter-induced pulmonary artery rupture

The use of PCR to amplify a specific virA gene fragment serves as a highly specific and sensitive method to detect virulent bacteria of the genus Shigella and enteroinvasive Escherichia coli. Amplification of a 215-bp DNA band was obtained by using isolated genomic DNA of Shigella, individual cells of Shigella dysenteriae, and mayonnaise contaminated with S. dysenteriae. Moreover, a multiplex PCR with specific (virA) and bacterium-restricted (16S ribosomal DNA) primers generated an amplification product of approximately 755 bp for all bacteria tested and an additional 215-bp product for Shigella and enteroinvasive E. coli.     

Investigation of the sedimentation of FeNi fine grains entrained in ERF slag

Nickel losses in the slag generated at Larco electric reduction furnaces (ERF) during smelting of Greek laterites account for about 20% of the total nickel of the feed. The recovery of the nickel contained in the slag as well as in its magnetic concentrate was studied under different methods. The experimental results have shown that a nickel recovery in the range of 75-90% is possible by allowing the slag to settle. Washing by low carbon steel can be performed during the final stages of the settling process as it improves the finally attained nickel recovery up to 94.4%. The simultaneous carbon reduction and settling process do not favour the Ni- recovery as the produced carbon monoxide and dioxide cause boiling of the bath which promotes the flotation of the metallic grains. In all cases a reoxidation of nickel was observed after 20min approximately. Settling of the ferronickel grains was described by a mathematical model. The model's results are in good agreement to the experimental ones for the initial 20min of the process. A modified model was elaborated combining the settling of the metallic grains with the nickel reoxidation reaction. This model describes with adequate accuracy the whole Ni- recovery process. The developed model can be proven helpful in the design of a slag cleaning step for metal recovery utilizing a slag settling furnace operating on line to the ERF.     

Accelerated collection of sensor data by mobility-enabled topology ranks

We study the problem of fast and energy-efficient data collection of sensory data using a mobile sink, in wireless sensor networks in which both the sensors and the sink move. Motivated by relevant applications, we focus on dynamic sensory mobility and heterogeneous sensor placement. Our approach basically suggests to exploit the sensor motion to adaptively propagate information based on local conditions (such as high placement concentrations), so that the sink gradually “learns” the network and accordingly optimizes its motion. Compared to relevant solutions in the state of the art (such as the blind random walk, biased walks, and even optimized deterministic sink mobility), our method significantly reduces latency (the improvement ranges from 40% for uniform placements, to 800% for heterogeneous ones), while also improving the success rate and keeping the energy dissipation at very satisfactory levels.     

Randomized priority algorithms

Borodin, Nielsen and Rackoff [13] introduced the class of priority algorithms as a framework for modeling deterministic greedy-like algorithms. In this paper we address the effect of randomization in greedy-like algorithms. More specifically, we consider approximation ratios within the context of randomized priority algorithms. As case studies, we prove inapproximation results for two well-studied optimization problems, namely facility location and makespan scheduling.     

Efficient medium arbitration of FSAN‐compliant GPONs

The steadily rising demand for multimedia and data services, the falling cost and omnipresence of Ethernet and the maturity of passive optical networks (PON) technology, promise to radically change the landscape in the local loop. The heart of a gigabit PON system (recently standardized by FSAN/ITU) is the medium access controller (MAC), which arbitrates access to the upstream link among users with fluctuating traffic demands and effects the multiplexing and concentration policy. At the same time, it has to safeguard the service quality and enforce the parameters agreed in the service level agreements (SLAs) between the users and the service provider. In this paper, a MAC protocol designed to serve any mix of services according to their quality of service (QoS) needs, employing four priority levels along with a high number of logically separate data queues is presented. The architecture and implementation in hardware of a MAC algorithm capable of allocating bandwidth down to a resolution of a byte with QoS differentiation is the focus of this paper. It employs the bandwidth arbitration tools of the FSAN/ITU G.984.3 standard and maps SLA parameters to GPON service parameters to create an efficient, fair and flexible residential access system. Copyright © 2005 John Wiley & Sons, Ltd.     

Testing and applications of a process model in the metallurgical production practice of ferronickel from laterites

A mathematical model of the electro-reduction furnace process (ERF process), for the production of ferronickel from laterite ores, has been tested at Larco's metallurgical plant at Larymna Greece. The theoretical predictions for the progress of the nickel reduction have been compared with the operational results. The tests were carried out in the ERF no. 2 of Larco's plant. The influence of the main process variables on the nickel recovery and nickel losses in the ERF slags have been investigated in conjunction with the variation of the analysis of the feed and the nickel content of the metal bath. The further application of the model to the metallurgical practice is discussed. According to the predictions of the model the further development of the process in the direction of the production of low-nickel ferronickel (Ni < 15%) is analyzed. The advantages of the production of low-nickel ferronickel are presented and the possibility of its straight conversion to nickel-bearing steel-grades is discussed.     

Sintered esseneite–wollastonite–plagioclase glass–ceramics from vitrified waste

Dense sintered esseneite–wollastonite–plagioclase glass–ceramics have been successfully prepared from a vitrified mixture of important inorganic waste (Bayer process red mud, fly ash from lignite combustion and residues from the polishing of porcelain stoneware tiles). The enhanced nucleation activity of fine glass powders, favoured by particular oxidation conditions, caused a substantial crystallisation, even in the case of very rapid thermal treatments at 900 °C, which led to remarkable mechanical properties (bending strength and Vickers micro-hardness exceeding 130 MPa and 7 GPa, respectively) and a promising chemical durability.     

A transparent MAC method for bandwidth sharing and CDV control atthe ATM layer of passive optical networks

In the quest for a way to bring local loop costs down and make B-ISDN affordable to small traffic customers, the passive optical networks (PONs) in combination with ATM (APONs) have been investigated extensively. To achieve the required medium sharing on a time division multiplexing (TDMA) basis, an arbitration mechanism is required in the upstream direction. The resulting multiplexing and concentration, though it is the source of significant savings, it has been plagued by the penalty of high distortion of the traffic profiles at the exit of the PON. The preventive congestion control method of ATM is rather intolerant of such distortions in the multiplexing stages. Arbitration methods which are either semistatic or based on number of arrivals per reservation period, cause very high cell delay variation (CDV). The cell clustering introduced by the arbitration method cannot be distinguished from peak rate violations of the contract by the policing unit. The result is either unwarranted rejections of conforming cells or unacceptably low utilization. The scheme presented herewith maintains a CDV behavior comparable to that of a common centralized FIFO multiplexer. It relies on a meticulous recording of the arrival timing of cells enabling a subsequent allocation of slots which produces almost the same output (and CDV) as the centralized FLFO multiplexer. A compact coding of the timing information restricts bandwidth waste for control information to the size found in other similar protocols. The most important feature is that the scheme is amenable to easy hardware implementation and does not require any call related information     

Effect of firing temperature and atmosphere on sintering of ceramics made from Bayer process bauxite residue

Bauxite residue, the principal waste from the Bayer process, was dried, pressed and studied for its thermal and sintering behaviour under different atmospheres, up to 1100 °C. For sintering in air and N₂, shrinkage begins at 800 °C and ranges from 2.6% to 13.9%, after firing at 1000–1100 °C. Bulk density varies from 1.7 to 2.3 g/cm³ whereas water absorption from 31.5% to 17.7%. The main crystalline phases identified on firing in air were hematite (Fe₂O₃), gehlenite (Ca₂Al₂SiO₇) and perovskite (CaTiO₃) whereas magnetite (Fe₃O₄) was also found on firing in N₂. Microstructures are characterised by irregularly shaped, <20 μm Feret diameter, pores in a ceramic matrix with interconnected porosity. The average pore size is greater in samples fired in N₂. On sintering in 4%H₂/Ar, shrinkage begins at 710 °C. After firing at 1100 °C, shrinkage is 20.1% and water absorption 1%. The main crystalline phases are magnetite, wustite (FeO), gehlenite and perovskite. Microstructures are characterised by a compact heterogeneous matrix, with isolated <15 μm Feret diameter, closed pores. The grains have reacted with the adjacent phase and their shape is rounded with no sharp facets. Increased sintering temperature results in improved physical properties for all atmospheres tested and in higher average pore size when sintering takes place in air and N₂. The use of magnetite-reducing sintering conditions can potentially assist in the production of a variety of ceramic compositions containing bauxite residue.     

Use of boron wastes in the production of heavy clay ceramics

Colemanite, ulexite and tincal are the main boron ores found in Turkey and account to 63% of the world estimated reserves. The production route of boron products results in significant amounts of different types of Boron Wastes, BW. Their open field disposal raises substantial environmental concerns in fear of leaching and groundwater pollution. The heavy clay ceramic industry can potentially absorb substantial quantities of BW. In the present study, BW produced from Kirka borax plants in Turkey, with 12.6 wt.% B₂O₃ was introduced in 0 wt.%, 5 wt.% and 15 wt.% in a heavy clay body mixture. Four peak temperatures, 800 °C, 850 °C, 900 °C and 950 °C, were examined for the dry pressed samples. The thermal behaviour analyzed by dilatometry and TGA shows that major loss in weight starts about 600 °C and continues to 700 °C approximately. For 5 wt.% BW addition and firing at 900–950 °C, the sintered bodies present comparable or improved physical and mechanical properties with respect to the reference formulation. The microstructure was analyzed by SEM whereas the main crystalline phases were identified by XRD. Samples fired at 900 °C with 5 wt.% BW present comparable properties with the reference ones. At 950 °C, the obtained properties were improved. Deformation occurs for samples with 15 wt.% BW when fired at >900 °C.