Relationship between efficacy of defibrillation shocks and frequency characteristics of shock waveforms

INTRODUCTION: Using the Fourier transform, it is possible to replace each time domain representation of a defibrillatory shock by a unique frequency domain representation in which the shock waveform is defined in terms of a complex number function of frequency and typically described as an amplitude in amperes per hertz (or, closely related, joules per hertz) and an associated frequency-dependent phase angle. METHODS AND RESULTS: The present article describes the conceptual basis of the Fourier transform, sketches a simplified mathematical framework for deriving frequency domain parameters, considers properties crucial to interpreting defibrillatory-type shocks when expressed in the frequency domain, and then presents a series of shock waveforms in the frequency domain. Although not definitive, knowledge of the energy distribution with frequency alone, usually presented in joules per hertz, is shown to yield considerable insight into the probable comparable efficacy of uniphasic/biphasic rectangular, untruncated/truncated uniphasic exponential, and various biphasic "single capacitor" waveforms. CONCLUSION: In general, efficacy in achieving ventricular defibrillation is improved by parameter changes that shift a larger percentage of the delivered energy into a mid-frequency range (very roughly, 40 to 160 Hz). With further study, the frequency domain approach may prove to be a useful tool in the a priori selection of optimal defibrillatory shock waveforms.     

Aging and prospective memory: The influence of increased task demands at encoding and retrieval.

A feature of prospective memory tasks is that they tend to be embedded into other background activities. Two experiments examined how the demands of these background activities affect age differences in prospective memory. The first experiment showed that increasing the demands of the background activities (by adding a digit-monitoring task) significantly reduced prospective memory performance. Planned comparisons revealed that age differences in prospective memory were reliable only in the more demanding background condition. The second experiment revealed significant prospective memory declines when the demands were selectively increased at encoding for both younger and older adults. When the demands were selectively increased at retrieval, older adults were particularly affected. The authors propose a model that relies on both automatic retrieval processes and working memory resources to explain prospective memory remembering. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prevention of bacterial adherence to implant surfaces with a crosslinked albumin coating in vitro

Titanium surfaces were coated with bovine serum albumin using carbodiimide, a crosslinking agent. The durability of the coated surfaces and the inhibitory effect of the albumin coating on bacterial adherence were tested in vitro for 20 consecutive days at 37 degrees C in phosphate buffered saline, with intermittent agitation. The results showed that only 10% of the coated bovine serum albumin decayed off the surface during the 20-day incubation period. The inhibition rate of the albumin coating on bacterial adherence remained high (greater than 8.5%) throughout the experiment. The results suggested potential use of this crosslinked albumin coating to reduce bacterial adherence and thus the subsequent possibility of prosthetic or implant infection in vivo.     

Use of later records in dairy sire evaluation: a review

Performance in first lactation has been the standard of evaluation for most genetic studies with dairy cattle. First records are available sooner on more cows and are less susceptible to error from selection, injury, previous days dry, and mastitis than are later records. However, first records have been considerably less than perfect in predicting traits of lifetime performance, which should be the primary selection objective in dairy cattle. Later records provide additional information for more accurate sire evaluations and should be a better index of health and resistance to mastitis than first lactations. The economic importance of later records relative to first is that there are more and actual yields are higher. Herds with more older cows can reduce commitment of resources to heifer rearing, and heifers can be selected more intensely prior to first calving than herds with more cows of younger ages. Some sire evaluation systems ignore later records because of computational expense, potential selection bias, and difficulty of age adjustment. Later records may contain useful information relative to lifetime profitability of sire progeny groups. Development of proper methodology for utilizing information available in later records appears fruitful for research.     

Cue-Focused and Reflexive-Associative Processes in Prospective Memory Retrieval.

Several theories of event-based prospective memory were evaluated in 3 experiments. The results depended on the association between the target event and the intended action. For associated target-action pairs (a) preexposure of nontargets did not reduce prospective memory, (b) divided attention did not reduce prospective memory, (c) prospective memory was better than when the target event and intended action were not associated, and (d) prospective memory was characterized by retrieval of the precise intended action. These results converge on the view that retrieval is mediated by a reflexive-associative process. In contrast, for unassociated pairs (a) preexposure of nontargets reduced prospective memory, and (b) divided attention reduced prospective memory. These results implicate cue-focused retrieval processes and are most consistent with a discrepancy-plus-search model. The entire pattern implicates both cue-focused and reflexive-associative processes and more generally supports a multiprocess framework of prospective memory (M. A. McDaniel & G. O. Einstein, 2000). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generation effects in free recall: Further support for a three-factor theory.

A framework is presented that helps explain and predict generation effects in free recall (for between-Ss manipulations of generating vs reading). When the targets share common features and when that shared information is salient to Ss, Ss will exploit that information to help generate the target items. This produces more relational processing among the targets (relative to reading), enhancing free recall. Consistent with this idea, when shared information (among targets) was salient, generation effects in free recall were found under encoding conditions that can disrupt generation effects in cued recall (e.g., pairing targets with unrelated cues). Further, within the same list, generation effects emerged in free recall for targets that were processed after shared information became evident but not for targets processed prior to the availability of the shared information. In recognition, generation effects were found for targets regardless of when they were processed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transport properties of gaseous ions over a wide energy range. Part II

This paper is a supplement to and extension of “Transport Properties of Gaseous Ions over a Wide Energy Range,” by H. W. Ellis, R. Y. Pai, E. W. McDaniel, E. A. Mason, and L. A. Viehland, Atomic Data and Nuclear Data Tables17, 177–210 (1976). The previous paper presented a compilation of experimental ionic mobility data available in February 1976. The present article brings the mobility compilation up to date as of August 1978 and also presents data on ionic diffusion coefficients obtained from the time of the first good measurements up to August 1978. (Both longitudinal and transverse diffusion coefficients are included.) The criteria for selection of the mobility and diffusion data were (1) the measurements must cover a reasonably wide range of $\text{E}\text{N}$, the ionic energy parameter, (2) the identity of the ions must be well established, and (3) the accuracy of the data must be good. The mobility and diffusion data are tabulated as functions of $\text{E}\text{N}$. The theory of ionic mobility recently developed by Viehland and Mason is used to calculate zero-field mobilities for each ion-gas combination as functions of an effective common ion-gas temperature which ranges from 300°K up to thousands of degress, typically. The compilation of data is preceded by a discussion of the theory of ion transport in gases which serves to put the data compilation into perspective and show how it can be effectively utilized. The effects of inelastic collisions are briefly discussed. The use of mobility data to test or generate ion-neutral interaction potentials is described.     

Transport properties of gaseous ions over a wide energy range

A compilation of experimental data is presented for the mobilities of mass-identified ions in neutral gases at room temperature as a function of the ionic energy parameter $\text{E}\text{N}$, the ratio of electric field strength to neutral gas number density. The literature has been covered to February 1976. In addition, a recently developed theory of gaseous ion mobility is used to compute, for each ion-gas combination, the zero-field reduced mobility as a function of the common ion-gas temperature. Finally, it is shown how the tabulated data can be used to estimate the ionic diffusion coefficients and to obtain information about the ion-neutral interaction potential.