Nonmonotonic behavior of resistance in a superconductor-Luttinger liquid junction

Transport through a superconductor-Luttinger liquid junction is considered. When the interaction in the Luttinger liquid is repulsive, the resistance of the junction with a sufficiently clean interface shows nonmonotonic temperature- or voltage-dependence due to the competition between the superconductivity and the repulsive interaction. The result is discussed in connection with recent experiments on single-wall carbon nanotubes in contact with superconducting leads.Comment: Revtex4, 2 eps figure files, slightly revised from an earlier version submitted to PRL on 2001.12.

Effects of production parameters on microstructure and densification of iron/glass syntactic foam by conventional powder metallurgy

Iron and steel matrix syntactic foams have received a lot of attention owing to their high strength, temperature capability, and corrosion resistance. However, high melting point of the iron and steels complicates applications of some conventional production processes. Since few casting methods were proposed to fabricate iron and steel syntactic foams embedded with the ceramic and metal hollow spheres having macro diameters, most of the foams having micro ceramic and glass hollow spheres were fabricated through powder metallurgy (PM) process, which allows reduction of temperature levels by about 30~40% compared to the casting. Metal injection molding (MIM) was mostly used toward the iron and steel matrix foams because of requiring only limited adaptations for switching from making solid parts to syntactic foams and its capabilities for producing various geometries and sizes. However, if the shape allows the production of the part by conventional PM (pressing and sintering), MIM would in most cases be too expensive. To date, detailed fundamental researches on conventional PM process to fabricate the iron or steel syntactic foams have not been reported. Difficulties of the conventional PM process to fabricate the iron and steel syntactic foams are working pressures and temperatures. For compacting powders to make green bodies, high working pressures can assist the densification of the matrix during sintering while this can deform or fracture the hollow spheres embedded. In case of the foams with the glass hollow spheres, softening of the glass occurs at high temperature thus original shape of the hollow spheres cannot be preserved. Therefore, to overcome the difficulties and to produce sound sintered bodies, the investigation on the production parameters of the conventional PM to fabricate the iron and steel syntactic foams is necessary. In this study, the iron/glass hollow spheres syntactic foams were fabricated via the conventional PM process. Fabrications were conducted with considering different production parameters, which included the compaction pressures and sintering temperatures in conjunction with various volume fractions and particle sizes of the hollow spheres. The microstructures and densification behaviors of the fabricated syntactic foams were characterized by X-ray diffraction, optical microscope, scanning electron microscope and energy dispersion spectroscope

Evaluation of normalization methods for microarray data

BACKGROUND: Microarray technology allows the monitoring of expression levels for thousands of genes simultaneously. This novel technique helps us to understand gene regulation as well as gene by gene interactions more systematically. In the microarray experiment, however, many undesirable systematic variations are observed. Even in replicated experiment, some variations are commonly observed. Normalization is the process of removing some sources of variation which affect the measured gene expression levels. Although a number of normalization methods have been proposed, it has been difficult to decide which methods perform best. Normalization plays an important role in the earlier stage of microarray data analysis. The subsequent analysis results are highly dependent on normalization. RESULTS: In this paper, we use the variability among the replicated slides to compare performance of normalization methods. We also compare normalization methods with regard to bias and mean square error using simulated data. CONCLUSIONS: Our results show that intensity-dependent normalization often performs better than global normalization methods, and that linear and nonlinear normalization methods perform similarly. These conclusions are based on analysis of 36 cDNA microarrays of 3,840 genes obtained in an experiment to search for changes in gene expression profiles during neuronal differentiation of cortical stem cells. Simulation studies confirm our findings

THE HOT GAS DESULFURIZATION IN A COMPACT TWO BEDS SYSTEM INTEGRATED WITH COAL GASIFICATION AND FISHER-TROPSCH SYSTEM

The hot gas desulfurization (HGD) technique is one of the elemental technologies of syngas purification having both thermal efficiency and very low emissions. The HGD is a novel method to efficiently remove H2S and COS in the syngas with regenerable sorbents at high temperature and high pressure condition. We propose a compact hot gas desulfurization system by which its operability is improved in stabilizing pressure balances among units. The proposed compact two beds system has two bubbling beds, solid injection nozzle, solid conveying line, and riser. The compact desulfurization system was located between coal gasifier and Fisher-Tropsch (F-T) reactor to desulfurize syngas in order not to deactivate F-T catalyst. To check feasibility of the compact desulfurization system at high pressure condition, both cold mode and hot mode tests have been performed. In the integrated system, the compact desulfurization system has removed H2S and COS in the syngas and supplied the cleaned syngas to the F-T reactor during the continuous operation at high pressure condition

Comparisons of the GlideScope and Macintosh Laryngoscope in Tracheal Intubation by Medical Students on Fresh Human Cadavers

AbstractObjectiveThe GlideScope Video Laryngoscope (GS) is an intubating device that provides equal or better glottic views than conventional laryngoscopes, but correct tube placement is more time-consuming, even when performed by experienced operators. The aim of this study was to investigate the use of the GS compared with the more conventional Macintosh laryngoscope in easy and difficult tracheal intubation when performed by inexperienced medical students on fresh human cadaversPatients and MethodsForty-one medical students were assigned to perform tracheal intubation using the direct Macintosh laryngoscope (DL) and the GS. Each student was given four attempts, with a maximum of 180 seconds for each attempt, to successfully intubate the trachea with a 6.5-mm tracheal tube in each of two scenarios, one with an easy airway and the other with a difficult airway cadaver.ResultsThe total time of intubation for the easy airway cadaver was significantly longer in the GS group (61.4 ± 4.8 seconds vs. 40.6 ± 5.3 seconds; p < 0.001) despite the modified Cormack-Lehane scores showing no difference between the two groups. In the difficult airway cadaver, total time of intubation was significant shorter in the GS group (64.3 ± 6.5 seconds vs. 98.7 ± 10.2 seconds; p < 0.001)ConclusionMost inexperienced operators found the GS to be more time-consuming for tracheal intubation than DL in the easy airway cadaver. However, an obvious advantage was demonstrated when the GS was used for the difficult airway