342 research outputs found

    Die bestuursbevoegdheid van persone wat as rampverpleegsters by die Pretoriase Burgerlike Beskerming geregistreer is

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    The essential management role of the disaster nurse during disaster action was outlined, researched and described. Her competency to execute effectively disaster relief tasks before, during and after a disaster occurring outside a hospital, was studied Management tasks were identified which nurses should have mastered regarding disaster situations occurring outside hospital boundaries. Research data were gathered by means of a questionnaire on the biographic detail of disaster nurses registered with Civil Defence in Pretoria, in order to recommend a course specially aimed at fulfilling their requirements. The research project identified requirements of the disaster nurse for appropriate further training, practise and guidance regarding the identified management tasks. It became evident that training is required in most of the tasks, and a training course for nurses in disaster management was designed

    Cochlear implantation in South Africa (part 2)

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    Cochlear implantation is a timeous and cost-effective solution for severe-to-profound sensorineural hearing loss (SNHL) and has transformed the lives of many individuals with significant hearing loss. The advent of cochlear implantation has meant that, for the first time, one of the senses (hearing), having been entirely lost, can be restored. The previous article in this series sketched the problem of severe-toprofound SNHL, and how cochlear implantation can overcome this, how a cochlear implant (CI) works, the history of cochlear implantation and the principles of the multidisciplinary CI team. The current status of cochlear implantation in South Africa (SA) is the subject of discussion in this article, the second of this two-part series on cochlear implantation. It comprises a study of the best available current data on the status of CI in SA

    Risk evaluation with enhaced covariance matrix

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    We propose a route for the evaluation of risk based on a transformation of the covariance matrix. The approach uses a `potential' or `objective' function. This allows us to rescale data from different assets (or sources) such that each data set then has similar statistical properties in terms of their probability distributions. The method is tested using historical data from both the New York and Warsaw Stock Exchanges.Comment: see urbanowicz.org.p

    New Trading Practices and Short-run Market Efficiency

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    We document a large decrease in autocorrelation and increase in variance of recent short-run returns on several broad stock market indexes, over the 1983-89 period, 15-minute returns went from being highly positively serially correlated to practically uncorrelated. Over the past twenty years, daily and weekly autocorrelations have also fallen, we use transactions data to decompose short-run index autocorrelation into three components: bid-ask bounce, nontrading effects, and noncomtemporaneous cross-stock correlations in specialists' quotes. The first two factors do not explain the autocorrelation's decline. We argue that new trading practices have improved the processing of market-wide information, and that the recent decreases in autocorrelation and increases in volatility simply reflect these improvements.

    Theoretical and Numerical Analysis of an Optimal Execution Problem with Uncertain Market Impact

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    This paper is a continuation of Ishitani and Kato (2015), in which we derived a continuous-time value function corresponding to an optimal execution problem with uncertain market impact as the limit of a discrete-time value function. Here, we investigate some properties of the derived value function. In particular, we show that the function is continuous and has the semigroup property, which is strongly related to the Hamilton-Jacobi-Bellman quasi-variational inequality. Moreover, we show that noise in market impact causes risk-neutral assessment to underestimate the impact cost. We also study typical examples under a log-linear/quadratic market impact function with Gamma-distributed noise.Comment: 24 pages, 14 figures. Continuation of the paper arXiv:1301.648

    Veteran athletes exercise at higher maximum heart rates than are achieved during standard exercise (stress) testing

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    Objective. The stress electrocardiogram (sECG) is routinely used to screen individuals for underlying cardiac pathology before an exercise programme is prescribed. The underlying assumption is that the cardiac responses elicited during the sECG test are similar to those achieved during participation in sportiilg activities. However, this premise may be incorrect since the physical demands of different modes of exercise vary substantially.Design. Ten veteran league squash players (LSP), 10 social squash players (SSP), 10 league runners (LR), 10 social runners (SR) and 10 sedentary individuals (SED) were recruited for the study. All subjects completed a lifestyle questionnaire, a full medical examination and a routine sECG. Thereafter each subject's heart rate (HR) was monitored on two separate occasions while participating in sporting activity.Results. No sECG exercise-induced abnormalities were observed, although five subjects showed resting abnormalities. Maximal HR during the sECG, and maximal and mean HR during the field tests, were not significantly diHerent between groups. However, maximal HR was significantly higher in all groups during their sporting activities than during stress testing in the laboratory (P < 0.01).Conclusions. Maximal HR in veteran athletes during specific sporting activities was significantly higher than that attained during a routine sECG. This finding was not sport-specific, nor was it related to the level of competitiveness of the trial participants. These data show that a routine sECG is a submaximal test of exercise performance, and should be interpreted as such

    Longitudinal Study of Australian Volunteers (Phase 2)

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    Longitudinal Study of Australian Volunteers (2019-2021)

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    Estimating Portfolio Risk for Tail Risk Protection Strategies

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    We forecast portfolio risk for managing dynamic tail risk protection strategies, based on extreme value theory, expectile regression, Copula-GARCH and dynamic GAS models. Utilizing a loss function that overcomes the lack of elicitability for Expected Shortfall, we propose a novel Expected Shortfall (and Value-at-Risk) forecast combination approach, which dominates simple and sophisticated standalone models as well as a simple average combination approach in modelling the tail of the portfolio return distribution. While the associated dynamic risk targeting or portfolio insurance strategies provide effective downside protection, the latter strategies suffer less from inferior risk forecasts given the defensive portfolio insurance mechanics

    Birds of a Feather Eat Plastic Together: High Levels of Plastic Ingestion in Great Shearwater Adults and Juveniles Across Their Annual Migratory Cycle

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    Limited work to date has examined plastic ingestion in highly migratory seabirds like Great Shearwaters (Ardenna gravis) across their entire migratory range. We examined 217 Great Shearwaters obtained from 2008–2019 at multiple locations spanning their yearly migration cycle across the Northwest and South Atlantic to assess accumulation of ingested plastic as well as trends over time and between locations. A total of 2328 plastic fragments were documented in the ventriculus portion of the gastrointestinal tract, with an average of 9 plastic fragments per bird. The mass, count, and frequency of plastic occurrence (FO) varied by location, with higher plastic burdens but lower FO in South Atlantic adults and chicks from the breeding colonies. No fragments of the same size or morphology were found in the primary forage fish prey, the Sand Lance (Ammodytes spp., n = 202) that supports Great Shearwaters in Massachusetts Bay, United States, suggesting the birds directly ingest the bulk of their plastic loads rather than accumulating via trophic transfer. Fourier-transform infrared spectroscopy indicated that low- and high-density polyethylene were the most common polymers ingested, within all years and locations. Individuals from the South Atlantic contained a higher proportion of larger plastic items and fragments compared to analogous life stages in the NW Atlantic, possibly due to increased use of remote, pelagic areas subject to reduced inputs of smaller, more diverse, and potentially less buoyant plastics found adjacent to coastal margins. Different signatures of polymer type, size, and category between similar life stages at different locations suggests rapid turnover of ingested plastics commensurate with migratory stage and location, though more empirical evidence is needed to ground-truth this hypothesis. This work is the first to comprehensively measure the accumulation of ingested plastics by Great Shearwaters over the last decade and across multiple locations spanning their yearly trans-equatorial migration cycle and underscores their utility as sentinels of plastic pollution in Atlantic ecosystems
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