Regional myocardial blood flow during hyperemia induced by contrast agent in patients with coronary artery disease

Regional myocardial specific blood flow (regional specific flow) was measured at rest and during contrast hyperemia after the intracoronary injection of xenon-133. The changes in regional specific flow were transient, resulting in some compromise in one of the underlying restraints of the inert gas washout method, namely, the presence of a steady state. Therefore, to determine the clinical utility of this technique, regional specific flow values obtained with this method were correlated with the presence and severity of coronary artery disease as assessed from the coronary arteriogram and left ventriculogram. Regional specific flow during contrast hyperemia was 186+/- 11 (mean +/- 1 standard error of the mean) ml/min per 100 g in control patients and 115+/-5 in patients with coronary artery disease. There was an inverse relation between regional specific flow during contrast hyperemia and the percent coronary stenosis when the stenosis was 40 percent or greater (r = 0.70, P less than 0.001). Regional specific flow was significantly less in patients with asynergy (77 +/- 10 ml/min per 100 g) than in patients with normal ventricular function (105 +/- 5) distal to coronary stenoses of greater than 75 percent. Thus regional specific flow measured during contrast hyperemia using the xenon washout technique and the Anger camera differentiated patients with normal coronary arteriograms from those with coronary artery disease. With this technique, good correlation was shown between regional specific flow and the percent coronary stenosis and presence of ventricular wall abnormalities. The information obtained with this method may provide prognostic information concerning suitability for surgical intervention.     

Reduction of CM Noise Emissions From PLC Modem Using Optically Coupled Signaling

This paper investigates the feasibility of implementing an optical coupler in the analog front-end (AFE) circuit of a power line communication (PLC) modem to reduce the common mode (CM) noise coupling onto the power lines. Based on a two-current-probe measurement approach, an equivalent CM circuit model is developed to predict the expected CM current generated by the PLC modem when it is plugged onto the power line network. The model provides insight into the CM noise coupling mechanism from any PLC modem onto the power line network, so that the effectiveness of using an optical coupling technique in reducing the CM current from the power line network can be properly quantified     

Effects of deliberate copper contamination from the platingsolution on the electrical characteristics of MOSFETs

N-channel and p-channel metal-oxide-semiconductor (MOS) transistors of various (W/L) ratios down to 0.24-μm channel length have been used to investigate the effects of deliberate backside copper (Cu) contamination on the MOS field-effect transistor (MOSFET) electrical parameters. The backside of the wafer was flooded with copper sulphate (CuSO₄) solution and air-dried. High-temperature annealing was carried out to drive Cu into silicon. It was discovered that the backside Cu contamination did not result in any undesirable effects on the MOS device performance. The MOS device parameters such as threshold voltage V_TO, transconductance G_m, drain saturation current I_DSAT, off-current I_off, and junction leakage current for n⁺/p and p+/n diodes displayed no significant degradation, even after 5 h of annealing at 400°C in nitrogen ambient. Secondary ion mass spectroscopy data shows that Cu diffused into silicon only over a short distance, leading to little or no degradation of MOSFETs and junction diodes     

Listening to discourse in distracting settings: The effects of aging.

Younger and older adults listened to discourse in quiet and in conversational noise, before answering questions concerning the material. Some questions required listeners to recall specific details; others were of a more integrative nature. When the listening situation was adjusted for individual differences in hearing, younger and older adults were equally adept at remembering the gist of the passages in both quiet and in two levels of noise. The two age groups also did not differ with respect to memory for specific details when listening in quiet or in a moderate level of noise, even when required to perform a concurrent task. Only at the loudest noise level did younger adults tend to recall more detail than older adults. However, when no adjustments were made to compensate for the poorer hearing of older adults (all participants tested under identical listening conditions), older adults could not recall as much detail as younger adults, either in quiet or in noise. The results indicate that the speech-comprehension difficulties of older adults primarily reflect declines in hearing rather than in cognitive ability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A novel noncooperative game competing model using generalized simple additive weighting method to perform network selection in heterogeneous wireless networks

Network selection mechanisms have a significant role in guaranteeing the QoS for users in a heterogeneous wireless networks environment. These mechanisms allow the selection of an optimal wireless network to satisfy the needs of users. Users are provided with the opportunity to select from multiple connectivity opportunities available all over various wireless networks. Furthermore, the network operators themselves can execute active selection strategies that facilitate proper decision making, in which user preferences are considered. This study proposes a new noncooperative competing game‐theoretic model and strategy space based on user preference. This model can solve network selection problems and capture the inter‐linkages of decisions taken by various networks. A generalized simple additive weighting method is incorporated into the framework of noncooperative game theory. In addition, the utility function is employed to assess the usefulness of the system. Simulation results and analysis illustrate the efficacy of the suggested model in attaining optimum network utility for heterogeneous wireless networks while optimizing user satisfaction. Copyright © 2014 John Wiley & Sons, Ltd.     

Klebsiella pneumoniae yggG Gene Product: A Zinc-Dependent Metalloprotease

Klebsiella pneumoniae causes neonatal sepsis and nosocomial infections. One of the strains, K. pneumoniae MGH 78578, shows high level of resistance to multiple microbial agents. In this study, domain family, amino acid sequence and topology analyses were performed on one of its hypothetical protein, YggG (KPN_03358). Structural bioinformatics approaches were used to predict the structure and functionality of YggG protein. The open reading frame (ORF) of yggG, which was a putative metalloprotease gene, was also cloned, expressed and characterized. The ORF was PCR amplified from K. pneumoniae MGH 78578 genomic DNA and cloned into a pET14-b vector for heterologous expression in Escherichia coli. The purified YggG protein was subsequently assayed for casein hydrolysis under different conditions. This protein was classified as peptidase M48 family and subclan gluzincin. It was predicted to contain one transmembrane domain by TMpred. Optimal protein expression was achieved by induction with 0.6 mM isopropyl thiogalactoside (IPTG) at 25 °C for six hours. YggG was purified as soluble protein and confirmed to be proteolytically active under the presence of 1.25 mM zinc acetate and showed optimum activity at 37 °C and pH 7.4. We confirmed for the first time that the yggG gene product is a zinc-dependent metalloprotease.     

Negative thermal expansion in a zirconium tungstate/epoxy composite at low temperatures

We have investigated a composite of cubic α-ZrW₂O₈ and epoxy with a high ceramic loading for its thermal expansion properties at cryogenic temperatures. The composite was fabricated by allowing the ceramic to sediment in the epoxy resin before curing, using only the dense bottom fraction of the composite for further measurements. Density measurements and thermogravimetric analysis showed that the samples repeatably consisted of approximately 60 vol% tungstate without significant voids. The coefficient of thermal expansion was measured by dilatometry at temperatures from 25 to 300 K, and we found negative thermal expansion occurring at temperatures below about 100 K. The observed behavior is consistent with predictions produced by a variational model, which shows that the high ceramic loading is necessary to reliably achieve negative thermal expansion in the composite. The composite has potential applications as compensators for unwanted thermal expansion at low temperatures and for fiber-optic cryogenic temperature sensors.