Transthoracic resistance in human defibrillation. Influence of body weight, chest size, serial shocks, paddle size and paddle contact pressure

Successful defibrillation depends on delivery of adequate electrical current to the heart; one of the major determinants of current flow is transthoracic resistance (TTR). To study the factors influencing TTR, we prospectively collected data from 44 patients undergoing emergency defibrillation. Shocks of 94-450 J delivered energy were administered from specially calibrated Datascope defibrillators that displayed peak current flow, thereby permitting determination of TTR. Shocks were applied from standard (8.5-cm diameter) or large (13 cm) paddles placed anteriorly and laterally. First-shock TTR ranged from 15-143 omega. There was a weak correlation between TTR and body weight (r = 0.45, p less than 0.05) and a stronger correlation between TTR and chest width (r = 0.80, p less than 0.01). Twenty-three patients who were defibrillated using standard 8.5-cm paddles had a mean TTR of 67 +/- 36 omega (+/- SD), whereas 21 patients who received shocks using paddle pairs with at least one large (13 cm) paddle had a 21% lower TTR of 53 +/- 24 omega (p = 0.05, unpaired t test). Ten patients received first and second shocks at the same energy level; TTR declined only 8%, from 52 +/- 19 to 48 +/- 16 omega (p less than 0.01, paired t test). In closed chest dogs, shocks were administered using a spring apparatus that regulated paddle contact pressure against the thorax. Firmer contact pressure caused TTR to decrease 25%, from 48 +/- 22 to 36 +/- 17 omega (p less than 0.01, paired t test). Thus, human TTR varies widely and is related most closely to chest size. TTR declines only slightly with a second shock at the same energy level. More substantial reductions in TTR and declines only slightly with a second shock at the same energy level. More substantial reductions in TTR and increases in current flow can be achieved by using large paddles and applying firm paddle contact pressure.     

CW high-power single-mode operation of gain-guided stripe-geometry multiple-quantum-well lasers

Stripe-geometry multiple-quantum-well GaAs-GaAlAs lasers grown by MO-CVD are reported to operate fundamental spatial and longitudinal mode up to more than 40 mW CW.     

Low-velocity gunshot wounds to extremities

Several therapeutic modalities in the management of low-velocity gunshot wounds to extremities were investigated. Local excision of wound margins, irrigation, and primary or delayed primary closure without the use of the operating room or prophylactic antibiotics produced results which were comparable to those obtained with a more aggressive surgical protocol.     

A general Martingale approach to discrete-time stochastic control and estimation

A general method of constructing system models for the solution of discrete-time stochastic control and estimation problems is presented. The method involves the application of modern martingale theory and entails the judicious choice of certain sigma-algebras and martingales. General estimation equations are derived for observations taking values in a countable space, and previously obtained estimation equations are exhibited as special cases. Finally, an example of the application of these methods to a stochastic control problem is analyzed.     

Low-threshold single quantum well (60 ?) GaAlAs lasers grown by MO-CVD with Mg as p-type dopant

The letter reports low-threshold MO-CVD GaAlAs DH (~7730 ?) lasers containing Mg as the p-type dopant. The structure consists of symmetric stepped index cladding layers on both sides of a thin single quantum well (~60 ?) active region. Broad-area threshold current densities of 460 A cm?2 and 270 A cm?2 are achieved for cavity lengths of 250 and 500 ?m, respectively. Broad-area room-temperature lasers without facet coatings emit in excess of 400 mW/facet CW output power.     

TRANSPORTATION,RACE AND EMPLOYMENT: IN PURSUIT OF THE ELUSIVE TRIAD

The purpose of this paper is to re-examine the question of whether minorities have greater difficulties in finding and holding jobs because of the poor public transportation serving their neighborhoods and the relatively low ownership of automobiles. Earlier studies generally concluded that transportation was not a major reason for the high unemployment and low incomes characteristic of inner city minority areas. We review this literature and conclude that previous findings may understate the relationship. From survey data of workers in three companies and unemployed workers seeking jobs in the same labor market, we examine whether there are statistically significant differences by race or ethnicity associated with transportation need, availability and use. Our findings indicate that transportation does play an important role in differences in labor market outcomes for minorities and nonminorities. We also find that these outcomes are different for blacks and Latinos.     

A note on an LQG regulator with Markovian switching and pathwiseaverage cost

We study a linear system with a Markovian switching parameter perturbed by white noise. The cost function is quadratic. Under certain conditions, we find a linear feedback control which is almost surely optimal for the pathwise average cost over the infinite planning horizon     

Believability of expert and lay witnesses: Implications for trial consultation.

Attorneys are often skeptical, with good reason, about the extent to which research findings and psychological principles may apply to the members of their jury pool. It is important for attorneys as well as psychologists who provide consultation services to have access to base-rate opinions about the consultation issues. This article reports the results of a statewide telephone survey of 488 adult residents who answered questions about the believability of expert witnesses and criminal defendants who testify. The survey questions were designed to provide "local" base-rate data about issues that arise in 3 areas of consultation work with attorneys: public perceptions of witness preparation with criminal defendants, expectations of criminal defendant demeanor, and judgments with respect to expert-witness characteristics that might be associated with being a "hired gun." Implications for psychologists who work as trial consultants and expert witnesses are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Methods for measuring stiffness of young trees

Pinus radiata clones with high modulus of elasticity (MOE). Various ways of measuring MOE are examined: traditional static bending, axial compression of bolts, existing sonic methods, as well as a tool specifically configured for resonance on short bolts. Wood characteristics and microfibril angle are measured on discs taken from each tree. Results show a good correlation between acoustic and static measurements of modulus of elasticity. Moreover, the selected seven radiata clones differ in stiffness by a factor of two, and much of this variation seems to relate to differences in microfibril angle. The results validate the assumption that there is potential to improve wood stiffness of radiata pine genetically. This work does not offer definitive solutions but explores a number of approaches that could be utilised as a selection tool in tree breeding for better product performance of radiata lumber. Here, development of methods based on acoustics is shown to assist in the necessary mass screening of clones for stiffness properties.

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Pinus radiata mit hohen MOE-Werten zu selektieren. Verschiedene Methoden zur MOE-Messung werden untersucht: konventionelle statische Biegetests, axiale Kompression von St?ben, vorhandene (Ultra)-Schallmethoden, sowie ein spezielles Ger?t zum Messen der Resonanz von kurzen St?ben. Holzeigenschaften und Fibrillenwinkel wurden an Scheiben gemessen, die von jedem Baum entnommen wurden. Die Ergebnisse zeigen eine gute Korrelation zwischen akustischen und statischen Messungen des MOE. Die sieben ausgew?hlten Klone unterschieden sich in ihrer Steifigkeit um den Faktor 2, wobei ein Gro?teil dieser Variationen mit Unterschieden im Mikrofibrillenwinkel zusammenh?ngt. Die Ergebnisse best?tigen die Vermutung, da? ein Potential zum Verbessern der Holzfestigkeit durch genetische Methoden bei Pinus radiata vorhanden ist. Diese Arbeit bietet keine definitiven L?sungen. Sie untersucht eine Anzahl von Ans?tzen zur Selektion bei der Züchtung im Hinblick auf bessere Schnittholzprodukte. Die entwicklung von akustischen Methoden erwies sich als hilfreich beim notwendigen Massen-Screening der Festigkeitseigenschaften der Klone.