4935452
A summary of the theory of velocity selective neural recording
This paper describes improvements to the technique of velocity selective recording (VSR) in which multiple neural signals are matched and summed to identify excited axon populations in terms of velocity. This form of recording has been termed intrinsic velocity selective recording (IVSR). The signals are acquired using a multi-electrode cuff (MEC) which is now available as a component for use in implantable neuroprostheses. The improvements outlined in the paper involve the use of bandpass filters at the output of the system which allows a higher level of selectivity to be obtained than is possible using IVSR.
24529809
Multiple-electrode nerve cuffs for low-velocity and velocity-selective neural recording
In the paper, a method using multiple-electrode nerve cuffs is presented that enables electroneurographic signals (ENG) to be recorded selectively by action potential velocity. The theory uses a one-dimensional model of the electrodes in the cuff. Using this model, the transfer function for a single tripole is derived, and it is shown that more than one tripole signal can be recorded from within a cuff. When many tripole signals are available and are temporally aligned by artificial delays and summed, there is a significant increase in the amplitude of the recorded action potential, depending on the cuff length and the action potential velocity, with the greatest gain occurring for low velocities. For example, a cuff was considered that was constrained by surgical considerations to 30 mm between the end electrodes. For action potentials with a velocity of 120 ms−1, it was shown that, as the number of tripoles increased from one, the peak energy spectral density of the recorded output increased by a factor of about 1.6 with three tripoles, whereas, for 20 ms−1, the increase was about 19, with ten tripoles. The time delays and summation act as a velocity-selective filter. With consideration of the energy spectral densities at frequencies where are maximum (to give the best signal-to-noise ratio), the tuning curves are presented for these velocity-selective filters and show that useful velocity resolution is possible using this method. For a 30 mm cuff with nine tripoles, it is demonstrated that it is possible to resolve at least five distinct velocity bands in the range 20–120 ms−1.
11981798
The theory of velocity selective neural recording: a study based on simulation
This paper describes the improvements to the theory of velocity selective recording and some simulation results. In this method, activity in different groups of axons is discriminated by their propagation velocity. A multi-electrode cuff and an array of amplifiers produce multiple neural signals; if artificial delays are inserted and the signals are added, the activity in axons of the matched velocity are emphasized. We call this intrinsic velocity selective recording. However, simulation shows that interpreting the time signals is then not straight-forward and the selectivity Qv is low. New theory shows that bandpass filters improve the selectivity and explains why this is true in the time domain. A simulation study investigates the limits on the available velocity selectivity both with and without additive noise and with reasonable sampling rates and analogue-to-digital conversion parameters. Bandpass filters can improve the selectivity by factors up to 7 but this depends on the speed of the action potential and the signal-to-noise ratio.
205914062
Chapter 3. Replication of the hepatitis delta virus RNA genome.
Hepatitis delta virus (HDV) is a subviral agent dependent upon hepatitis B virus (HBV). HDV uses the envelope proteins of HBV to achieve assembly and infection of target cells. Otherwise, the replication of the RNA genome of HDV is totally different from that of its helper virus, and involves redirection of host polymerase activity. This chapter is concerned with recent developments in our understanding of the genome replication process.
44845847
Human hepatitis delta virus: an agent with similarities to certain satellite RNAs of plants.
One of the most intriguing aspects of hepatitis delta virus (HDV) is that, even though it is a naturally occurring infectious agent of human beings, it nevertheless shows a number of remarkable similarities to viroids, the subviral agents of plants that are considered elsewhere in this volume. The recognition and exploitation of this analogy has been a major contributor to studies of HDV genome replication. This review will concentrate on the structure of the HDV genome and the mechanism by which the genome is replicated, with special emphasis on similarities to the viroids. The review will not consider in any depth other important aspects of HDV, such as the assembly of genomes into virus particles, experimental transmission, host responses, or epidemiology. For such information the reader is directed to other more extensive reviews (Lai 1995; Purcell and Gerin 1996; Hadziyannis 1997; Margolis et al. 1997). However, to put this review in perspective, we will present a limited amount of background material.
3459683
Quality improvements in resident mobility care: using person- and relationship-centered frameworks.
PURPOSE OF THE STUDY
Research is needed to demonstrate the application of person- and relationship-centered care to nursing home practice. This article aimed to find a suitable person/relationship-centered framework to assist with mobility care practice improvements in nursing homes.


DESIGN AND METHOD
The authors discuss the task of mobility care, the nature of person- and relationship-centered care, and the significance of such approaches to mobility care. The Senses Framework (Nolan, Davies, Ryan, & Keady, 2008) is employed to develop mobility care practice improvement objectives.


RESULTS
The objectives are used to evaluate outcomes from 2 hypothetical scenarios to illustrate the possible value of the Senses Framework.


IMPLICATIONS
The Senses Framework facilitated development of objectives for mobility care practice improvement that considers the needs of all stakeholders.
21326002
Life events and peer substance use and their relation to substance use problems in college students.
Substance use disorders among college students are not well understood, and the present study examined the relationship of two environmental factors to alcohol and drug use problems in 616 (316 women) college students. Participants completed measures assessing substance use problems, life events, and substance use among peers. Alcohol use problems were significantly associated with higher drug use problems and regular use of illicit drugs among friends. Drug use problems were significantly associated with male gender, higher alcohol use problems, regular use of alcohol and drugs among friends, illicit drug use among romantic partners, and higher numbers of negative life events. Results extend previous research and suggest that college students who experience multiple negative life events and/or affiliate with substance using friends and romantic partners may be at risk for developing a substance use problem.
28897037
The synthesis of RNA by mammalian cells treated with the aminonucleoside of puromycin.
Abstract The aminonucleoside of puromycin will inhibit RNA synthesis in cultured hamster embryo cells with little effect on protein synthesis for several hours. In other systems, the drug-induced inhibition of RNA synthesis has been interpreted as a specific inhibition of ribosomal RNA (rRNA) synthesis with only a small effect on messenger RNA (mRNA) synthesis. In contrast, no evidence was found in this system for such a selective inhibition, as the synthesis of rRNA, ‘heavy nuclear’ RNA, and polysomal mRNA were all inhibited to approximately equal extent by the drug. In addition, the results are consistent with the interpretation that rRNA synthesized in the presence of the drug is open to more than normal degradation during its maturation and incorporation into ribosomes.