Pacemaker interference by magnetic fields at power line frequencies

Human exposure to external 50/60-Hz electric and magnetic fields induces electric fields within the body. These induced fields can cause interference with implanted pacemakers. In the case of exposure to magnetic fields, the pacemaker leads are subject to induced electromotive forces, with current return paths being provided by the conducting body tissues. Modern computing resources used in conjunction with millimeter-scale human body conductivity models make numerical modeling a viable technique for examining any such interference. In this paper, an existing well-verified scalar-potential finite-difference frequency-domain code is modified to handle thin conducting wires embedded in the body. The effects of each wire can be included numerically by a simple modification to the existing code. Results are computed for two pacemaker lead insertion paths, terminating at either atrial or ventricular electrodes in the heart. Computations are performed for three orthogonal 60-Hz magnetic field orientations. Comparison with simplified estimates from Faraday's law applied directly to extracorporeal loops representing unipolar leads underscores problems associated with this simplified approach. Numerically estimated electromagnetic interference (EMI) levels under the worst case scenarios are about 40 microT for atrial electrodes, and 140 microT for ventricular electrodes. These methods could also be applied to studying EMI with other implanted devices such as cardiac defibrillators.     

Polychronicity, the Internet, and the Mass Media: A Singapore Study

Polychronicity is time-use preference, which people acquire through socialization. The literature shows that polychrons, who favor simultaneous activities, and monochrons, who favor linear activities, exhibit different perceptual and behavioral patterns. This article examines the relationship among polychronicity, Internet skills, Internet use, and Internet perception. In addition, it investigates the hypothesis that Internet use displaces other activity. A total of 1,048 adult Singapore citizens and permanent residents participated in a computer-assisted telephone interview. Of these, 380 were non-Internet users and 668 were users. For the purpose of this study, only responses from the 668 Internet users were included in the analyses. Two-stage least squares regression analyses showed that polychronicity was not associated with Internet use, but it predicted Internet perception. Internet skills positively predicted Internet use and perception. The Internet neither displaced nor promoted television viewing, radio listening, and newspaper reading. However, there was some indication that polychronicity suppressed television viewing.     

Web interaction using very small Internet devices

Internet-enabled cell phones typically accommodate only three to 12 text lines, and their design emphasizes portability. Web interaction has, so far, been a secondary concern. For the most part, automated techniques to address the feature gap between the desktop and these phonetops rely on the notion of transducing-translating HTML and images into formats compatible with small devices, which typically cannot handle HTML content. The authors have developed a Web browsing model that supports navigation and action in separate interfaces, To demonstrate the model, they created m-Links, a middleware proxy system that retrieves Web documents using HTTP, lets users navigate and apply services to Web content, and delivers a suitable user interface to a variety of small Web-capable wireless devices.     

Managing job seekers' organizational image beliefs: The role of media richness and media credibility.

In this article, the authors assessed job seekers' organizational image beliefs before and after they experienced 3 recruitment media. The authors examined whether perceptions of media richness and credibility were related to improvements in the correspondence between job seekers' image beliefs and firms' projected images. Both media richness and credibility perceptions were associated with correspondence between job seekers' image beliefs and firms' projected images. However, results revealed that richness and credibility perceptions were likely to enhance job seekers' initial beliefs about firms' images when their beliefs were positive but did not diminish job seekers' beliefs about firms' images when their initial impressions were too positive. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

探索PCI Express沟通芯片道

PCI Express技术可提供极快的速度、彻底改变通讯模式的特性已被业界广泛讨论,但很少有人论及PCI Express如何让芯片间进行通讯.在先前一系列PCI Express架构的技术文章中,我们已从虚拟通道的议题,一路探讨到应用与PC架构的领域.然而,连接PCI Express(PCIe)与ExpressCard组件的可编程接口是我们尚未探讨的主题,本文将针对该主题进行深入的探讨.     

Wind tunnel modelling as a means of predicting the response of chimmeys to vortex shedding

The limitations of wind tunnel testins, particularly for chimneys with a circular cross-section are discussed. The use of data from full-scale observations and wind tunnel tests at high Reynolds numbers in conjunction with suitable mathematical models are suggested to obtain wind load and wind response estimates that offer a higher level of reliability than wind tunnel estimates.     

Insertion element IS3-based PCR method for subtyping Escherichia coli O157:H7

An Escherichia coli O157:H7 subtyping method based on PCR amplification of variable DNA sequences between the repetitive element IS3 was developed. Template DNA was prepared by boiling cells in Chelex. Two separate IS3 PCR amplifications were performed for each isolate: one with a single primer (primer IS3A) and one with two primers (primers IS3A and IS3B). The IS3 PCR subtyping method was applied to 35 epidemiologically related and unrelated E. coli O157:H7 isolates that had been previously characterized by pulsed-field gel electrophoresis (PFGE). PFGE identified 25 different subtypes (difference of one or more bands). PCR with single primer IS3A and primer pair IS3A-IS3B identified 6 and 14 different subtypes, respectively. By combining the results of the two PCR amplifications, 15 different IS3 PCR subtypes were identified. While not as sensitive as PFGE, IS3 PCR subtyping grouped all outbreak-related isolates. IS3 PCR banding patterns were reproducible between amplifications and between subcultures. IS3 PCR could serve as a simple, rapid screening method for the identification of unrelated E. coli O157:H7 isolates.     

Antithrombins Wibble and Wobble (T85M/K): archetypal conformational diseases with in vivo latent-transition, thrombosis, and heparin activation

The inherent variability of conformational diseases is demonstrated by two families with different mutations of the same conserved aminoacid in antithrombin. Threonine 85 underlies the opening of the main beta-sheet of the molecule and its replacement, by the polar lysine, in antithrombin Wobble, resulted in a plasma deficiency of antithrombin with an uncharacteristically severe onset of thrombosis at 10 years of age, whereas the replacement of the same residue by a nonpolar methionine, antithrombin Wibble, gave near-normal levels of plasma antithrombin and more typical adult thromboembolic disease. Isolated antithrombin Wibble had a decreased thermal stability (Tm 56.2, normal 57.6 degreesC) but was fully stabilized by the heparin pentasaccharide (Tm 71.8, normal 71.0 degreesC), indicating that the prime abnormality is a laxity in the transition of the main sheet of the molecule from the 5- to 6-stranded form, as was confirmed by the ready conversion of antithrombin Wibble to the 6-stranded latent form on incubation. That this transition can occur in vivo was shown by the finding of nearly 10% of the proband's plasma antithrombin in the latent form and also, surprisingly, of small but definitive amounts of latent antithrombin in normal plasma. The latent transition will be predictably accelerated not only by gross mutations, as with antithrombin Wobble, to give severe episodic thrombosis, but also by milder mutations, as with antithrombin Wibble, to trigger thrombosis in the presence of other predisposing factors, including the conformational stress imposed by the raised body temperatures of fevers. Both antithrombin variants had an exceptional (25-fold) increase in heparin affinity and this, together with an increased inhibitory activity against factor Xa, provides evidence of the direct linkage of A-sheet opening to the conformational basis of heparin binding and activation.     

Protective effect of cysteine and vitamin E, Crocus sativus and Nigella sativa extracts on cisplatin-induced toxicity in rats

There are three ways to approach and resect the caudate lobe of the liver, that is; and isolated caudate lobectomy, a combined resection of the liver overlying the caudate lobe, and a transhepatic anterior approach by splitting parenchyma of the liver. We had two patients with neoplasms originating in the caudate lobe who underwent a complete caudate lobectomy. Both patients have been doing well without liver dysfunction. Although after the transhepatic anterior approach we anticipated an adverse effect from splitting the parenchyma of the liver, the postoperative course was uneventful and similar to that of the right side approach.     

Characterization by pyrolysis-gas chromatography-mass spectrometry of the insoluble organic residues derived from the hydrogenation of Tasmanites sp. oil shale

The insoluble organic residues from the hydrogenation of Tasmanites sp. oil shale have been characterized by Curie point pyrolysis combined with gas chromatography and computerized gas chromatography-mass spectrometry. The resulting pyrograms show that very little, if any, hydrogenation of the residues occurs. Rather, the initial step in the sequence is pyrolysis of the residue followed by hydrogenation of the liquid products. Major compounds identified from the pyrograms of the residues include alkene/alkane doublets, mixtures of diterpenoids and mono- di- and triaromatic compounds. Changes in the distribution of these compounds with changes in reaction conditions are discussed.