Performance improvement analysis for the Apollo unified S-band system Final report, Sep. 1968 - Aug. 1970

Communications system analyses techniques for Apollo unified S band optimizatio

Acute care nurses' perceptions of barriers to using research information in clinical decision-making

Aim. To examine the barriers that nurses feel prevent them from using research in the decisions they make. Background. A sizeable research literature focusing on research utilization in nursing has developed over the past 20 years. However, this literature is characterized by a number of weaknesses: self-reported utilization behaviour; poor response rates and small, nonrandom sampling strategies. Design. Cross-case analysis involving anonymised qualitative interviews, observation, documentary audit and Q methodological modelling of shared subjectivities amongst nurses. The case sites were three large acute hospitals in the north of England. One hundred and eight nurses were interviewed, 61 of whom were also observed for a total of 180 h, and 122 nurses were involved in the Q modelling exercise (response rate of 64%). Results. Four perspectives were isolated that encompassed the characteristics associated with barriers to research use. These related to the individual, organization, nature of research information itself and environment. Nurses clustered around four main perspectives on the barriers to research use: (1) Problems in interpreting and using research products, which were seen as too complex, 'academic' and overly statistical; (2) Nurses who felt confident with research-based information perceived a lack of organizational support as a significant block; (3) Many nurses felt that researchers and research products lack clinical credibility and that they fail to offer the desired level of clinical direction; (4) Some nurses lacked the skills and, to a lesser degree, the motivation to use research themselves. These individuals liked research messages passed on to them by a third party and sought to foster others' involvement in research-based practice, rather than becoming directly involved themselves. Conclusions. Rejection of research knowledge is not a barrier to its application. Rather, the presentation and management of research knowledge in the workplace represent significant challenges for clinicians, policy-makers and the research community

Global electric field determination in the Earth's outer magnetosphere using charged particles

Although many properties of the Earth's magnetosphere have been measured and quantified in the past 30 years since it was discovered, one fundamental (for a zeroeth order magnetohydrodynamic (MHD) equilibrium) measurement was made infrequently and with poor spatial coverage: the global electric field. This oversight is in part due to the difficulty of measuring a plasma electric field, and in part due to the difficulty of measuring a plasma electric field, and in part due to the neglect of theorists. However, there is renewed interest in the convection electric field, since it has been realized that it is vital for understanding many aspects of the magnetosphere: the global MHD equilibrium, reconnection rates, Region 2 Birkeland currents, magnetosphere-ionosphere coupling, ring current and radiation belt transport, substorm injections, acceleration mechanisms, etc. Unfortunately the standard experimental methods have not been able to synthesize a global field (excepting the pioneering work of McIlwain's geostationary models), and we are left with an overly simplistic theoretical field, the Volland-Stern electric field mode. Again, single point measurements of the plasma pause were used to infer the appropriate amplitudes of the model, parameterized by Kp (Maynard & Chen, JGR 1975). Although this result was never intended to be the definitive electric field model, it has gone nearly unchanged for 15 years. However, the data sets being taken today require a great deal more accuracy than can be provided by the Volland-Stern model. Nor has the variability of the electric field shielding been properly addressed, although effects of penetrating magnetospheric electric fields has been seen in mid- and low-latitude ionospheric data sets. The growing interests in substorm dynamics also requires a much better assessment of the electric fields responsible for particle injections. Thus, we proposed and developed algorithms for extracting electric fields from particle data taken in the earth's magnetosphere. As a test of the effectiveness of these techniques, we analyzed data taken by the AMPTE/CCE spacecraft in equatorial orbit between 1984-1988. Some analytic tools had to be developed before construction of computer algorithms, and they are discussed

The accessibility of research-based knowledge for nurses in United Kingdom acute care settings

Background. The successful dissemination of the results of the National Health Service (NHS) research and development strategy and the development of evidence based approaches to health care rely on clinicians having access to the best available evidence; evidence fit for the purpose of reducing the uncertainties associated with clinical decisions. Aim. To reveal the accessibility of those sources of information actually used by nurses, as well as those which they say they use. Design. Mixed method case site, using interview, observational, Q sort and documentary audit data in medical, surgical and coronary care units (CCUs) in three acute hospitals. Results. Three perspectives on accessibility were identified: (a) the humanist-in which human sources of information were the most accessible; (b) local information for local needs-in which locally produced resources were seen as the most accessible and (c) moving towards technology-in which information technology begins to be seen as accessible. Nurses' experience in a clinical specialty is positively associated with a perception that human sources such clinical nurse specialists, link nurses, doctors and experienced clinical colleagues are more accessible than text based sources. Clinical specialization is associated with different approaches to accessing research knowledge. Coronary care unit nurses were more likely perceive local guidelines, protocols and on-line databases as more accessible than their counterparts in general medical and surgical wards. Only a third of text-based resources available to nurses oil the wards had any explicit research base. These, and the remainder were Out of date (mean age of textbooks 11 years), and authorship hard to ascertain. Conclusion. A strategy to increase the use of research evidence by nurses should harness the influence of clinical nurse specialists, link nurses and those engaged in practice development. These roles Could act as 'conduits' through which research-based messages for practice, and information for clinical decision making, could flow. This role should be explored and enhanced

Meta-analysis of the Cepheid Xpert® CT/NG assay for extragenital detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections.

Background Most studies evaluating extragenital testing performance for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) detection by the Xpert® CT/NG show high per cent agreement with comparison assays; however, the precision around positive per cent agreement is low and thus the values that have been reported are not highly informative. Therefore, a systematic review was conducted and data from five studies were combined to better assess positive per cent agreement.MethodsThe literature indexed on PubMed.gov was searched. Included studies were those that were an evaluation of the Xpert CT/NG assay with rectal and/or pharyngeal specimen types compared with another nucleic acid amplification test (NAAT), the Aptima transcription mediated amplification assay. A full Bayesian method was used for bivariate fixed-effect meta-analysis of positive and negative per cent agreement and pooled estimates (and 95% confidence intervals (CI)) were presented for each.ResultsThe pooled positive and negative per cent agreement for detection of CT in rectal specimens was 89.72% (95% CI: 84.97%, 93.64%) and 99.23% (95% CI: 98.74%, 99.60%), and in pharyngeal specimens, they were 89.96% (95% CI: 66.38%, 99.72%) and 99.62% (95% CI: 98.95%, 99.95%) respectively. For NG detection in rectal specimens, the pooled positive and negative per cent agreement was 92.75% (95% CI: 87.91%, 96.46%) and 99.75% (95% CI: 99.46%, 99.93%), and in pharyngeal specimens, they were 92.51% (95% CI: 85.84%, 97.18%) and 98.56% (95% CI: 97.69%, 99.23%) respectively.ConclusionsIt was found that the Xpert CT/NG assay performed similarly to the Aptima transcription mediated amplification assay for the detection of CT and NG in extragenital specimens. The Xpert assay has the benefit of providing faster results at the point-of-care, thus reducing the turnaround time for results, potentially enabling same-day treatment

The discovery of trapped energetic electrons in the outer cusp

We report on the POLAR/CEPPAD discovery of a trapped, 60°\u3cθ\u3c120° pitch angle electron population in the outer cusp (7−9+ Re), whose energetic electron component extends from below 30 keV to ∼2 MeV. Because the time variability in the outer cusp precludes mapping with POLAR, we have carried out test particle simulations using the Tsyganenko 1996 model (T96) to demonstrate the trapping of these energy electrons in the outer cusp region and the resonant frequencies of its trapped motion. We discuss the boundaries and regions of the cusp trap and show that it is analogous to the dipole trap. We show that the phase space densities observed there are equal or greater than the phase space densities observed in the radiation belts at constant magnetic moment, thus allowing the possibility of diffusive filling of the radiation belts from the cus

Bond Repurchases: A Teaching Case

Companies can buy back and retire their own bonds before maturity, resulting in a possible gain or loss on the extinguishment of debt. What would happen if a company repurchased its own bonds before maturity but did not retire them, potentially holding them for resale later before the bonds mature? This case gives students an opportunity to explore how the repurchase of bonds held for resale should be accounted for, including the repurchase transaction, the disposition of any gain or loss, and the possible transaction to resell the bonds later

The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for maxBCG Galaxy Clusters

The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG-galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocity dispersion at fixed richness. The mean velocity dispersion increases from 202+/-10 km/s for small groups to more than 854+/-102 km/s for large clusters. We show the scatter to be at most 40.5+/-3.5%, declining to 14.9+/-9.4% in the richest bins. We test our methods in the C4 cluster catalog, a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2 spectroscopic sample, and in mock galaxy catalogs constructed from N-body simulations. Our methods are robust, measuring the scatter to well within one-sigma of the true value, and the mean to within 10%, in the mock catalogs. By convolving the scatter in velocity dispersion at fixed richness with the observed richness space density function, we measure the velocity dispersion function of the maxBCG galaxy clusters. Although velocity dispersion and richness do not form a true mass-observable relation, the relationship between velocity dispersion and mass is theoretically well characterized and has low scatter. Thus our results provide a key link between theory and observations up to the velocity bias between dark matter and galaxies.Comment: 25 pages, 15 figures, 2 tables, published in Ap

The neural consequences of attentional prioritization of internal representations in visual Working Memory

Although humans can hold multiple items in mind simultaneously, the contents of working memory (WM) can be selectively prioritized to guide future behavior. We explored whether the “same-object” benefits in visual processing may also be observed in visual WM. fMRI data were collected while participants performed a multistep serial retrocuing task in which they first viewed two 2-D objects (coherently moving colored dots). During retention, an initial relevance cue then indicated whether only the first or only the second object (“object-relevant”), or only the color of both objects or only their direction of motion would be relevant for the remainder of the trial (“feature-relevant”). On “object-relevant” trials, the ensuing priority cues selected either one the features (“color” or “direction”) bound to the relevance-cued object, whereas on “feature-relevant” trials, the priority cues selected one of the two relevance-cued features. Using multivariate inverted encoding models, we found a same-object benefit on object-relevant trials in occipitotemporal regions: On feature-relevant trials, the first priority cue triggered a strengthening of the neural representation of the cued feature and a concomitant weakening to baseline of the uncued feature, whereas on object-relevant trials, the cued item remained active but did not increase in strength and the uncued item weakened but remained significantly elevated throughout the delay period. Although the stimulus-specific representation in frontoparietal regions was weak and uneven, these regions closely tracked the higher order information of which stimulus category was relevant for behavior throughout the trial, suggesting an important role in controlling the prioritization of information in visual WM