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Search Results: 1 - 10 of 424802 matches for " M van Dyk "
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The Experiences of the Elderly and Caregivers in Respect of Caring for the Elderly in Windhoek and Rehoboth Namibia: An Exploratory and Descriptive Study  [PDF]
Joan M. Kloppers, Agnes van Dyk, Louise Pretorius
Open Journal of Nursing (OJN) , 2015, DOI: 10.4236/ojn.2015.53029
Abstract: In many instances, care for the elderly, especially in long-term care institutions, is provided under minimal supervision by caregivers who are lay people. This can lead to poor quality care or neglect of the elderly. The research question was: “How competent are lay caregivers for the elderly in old age homes, who often lack the opportunity for training to improve their knowledge and skills, in delivering care to the elderly? The aims of the study were to explore and describe the experiences of both the caregivers and the elderly in respect of caring for the elderly in old age homes. The objectives of the study were to explore and describe the experiences of the caregivers and the elderly with respect to caring for the elderly and in respect of nursing care they received. A qualitative, explorative, descriptive, contextual and phenomenology design was used to perform this study. In the situational analysis, the experiences and needs of the caregivers were described. Themes in terms of interpersonal relationships that could be positive or negative regarding the elderly were identified. These included lack of regular in-service training sessions for caregivers. Likewise, sub-themes like communication, support and caring for elderly people were revealed. Inadequate knowledge of caregivers in caring procedures, a shortage of staff, equipment and absence of policies which should support and guide the work of caregivers impacts negatively on the care of the elderly. From the experiences of the elderly and caregivers, the competencies under scrutiny emerged and were measured qualitatively by the perceptions of the elderly, in respect of the caring they were exposed to.
Hutchinson’s sign as a marker of ocular involvement in HIVpositive patients with herpes zoster ophthalmicus
M van Dyk, D Meyer Meyer
South African Medical Journal , 2010,
Abstract: Background. A positive Hutchinsonfs sign indicates an increased risk of ocular involvement in herpes zoster ophthalmicus (HZO). We examined the sensitivity of Hutchinsonfs sign as an indicator of ocular involvement in a consecutive series of patients presenting with HZO. Methods. We conducted a descriptive observational prospective study of patients .18 years old presenting with HZO and consenting to pre- and post-test counselling and HIV and CD4 testing. A full ophthalmological examination focused on the extent of ocular involvement, and the presence of Hutchinsonfs sign was confirmed by two clinicians. Results. Thirty-three patients were enrolled; 29 were HIV positive, of whom 18 (62%) had not been diagnosed with HIV prior to enrolment. Of the 29 HIV-positive patients, 21 (72%) were Hutchinsonfs sign positive (HSP), all of whom had intra-ocular involvement (95% confidence interval 88 - 100%) Of the 8 HIV-positive, Hutchinsonfs sign-negative (HSN) patients, 4 did and 4 did not display intra-ocular involvement. Neither the mean CD4 count nor the average age in the HSP group differed significantly from the HSN group. Conclusion. We confirmed that a Hutchinsonfs sign- and HIVpositive patient with HZO has a very high positive predictive value for intra-ocular involvement. Neither age nor CD4 count had predictive value for ocular involvement. Young adults presenting with HZO should be suspected of having HIV, and HIV-positive patients with HZO but HSN may still have ocular involvement. All patients with HZO should be seen by an ophthalmologist.
Histopatologiese veranderinge in die lewer van twee varswater visspesies in die Roodekopjesdam, Noordwes Provinsie: Voorlopige resultate
Byron M. Bester,J. C. van Dyk,G. M. Wagenaar
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2012, DOI: 10.4102/satnt.v31i1.295
A Bayesian Approach to Deriving Ages of Individual Field White Dwarfs
Erin M. O'Malley,Ted von Hippel,David van Dyk
Physics , 2013, DOI: 10.1088/0004-637X/775/1/1
Abstract: We apply a self-consistent and robust Bayesian statistical approach to determining the ages, distances, and ZAMS masses of 28 field DA white dwarfs with ages of approximately 4 to 8 Gyrs. Our technique requires only quality optical and near-IR photometry to derive ages with < 15% uncertainties, generally with little sensitivity to our choice of modern initial-final mass relation. We find that age, distance, and ZAMS mass are correlated in a manner that is too complex to be captured by traditional error propagation techniques. We further find that the posterior distributions of age are often asymmetric, indicating that the standard approach to deriving WD ages can yield misleading results.
Preprocessing Solar Images while Preserving their Latent Structure
Nathan M Stein,David A van Dyk,Vinay L Kashyap
Statistics , 2015,
Abstract: Telescopes such as the Atmospheric Imaging Assembly aboard the Solar Dynamics Observatory, a NASA satellite, collect massive streams of high resolution images of the Sun through multiple wavelength filters. Reconstructing pixel-by-pixel thermal properties based on these images can be framed as an ill-posed inverse problem with Poisson noise, but this reconstruction is computationally expensive and there is disagreement among researchers about what regularization or prior assumptions are most appropriate. This article presents an image segmentation framework for preprocessing such images in order to reduce the data volume while preserving as much thermal information as possible for later downstream analyses. The resulting segmented images reflect thermal properties but do not depend on solving the ill-posed inverse problem. This allows users to avoid the Poisson inverse problem altogether or to tackle it on each of $\sim$10 segments rather than on each of $\sim$10$^7$ pixels, reducing computing time by a factor of $\sim$10$^6$. We employ a parametric class of dissimilarities that can be expressed as cosine dissimilarity functions or Hellinger distances between nonlinearly transformed vectors of multi-passband observations in each pixel. We develop a decision theoretic framework for choosing the dissimilarity that minimizes the expected loss that arises when estimating identifiable thermal properties based on segmented images rather than on a pixel-by-pixel basis. We also examine the efficacy of different dissimilarities for recovering clusters in the underlying thermal properties. The expected losses are computed under scientifically motivated prior distributions. Two simulation studies guide our choices of dissimilarity function. We illustrate our method by segmenting images of a coronal hole observed on 26 February 2015.
Detection and characterisation of papillomavirus in skin lesions of giraffe and sable antelope in South Africa
E. van Dyk,A-M Bosman,E. van Wilpe,J. H. Williams
Journal of the South African Veterinary Association , 2012, DOI: 10.4102/jsava.v82i2.39
Abstract: Papillomavirus was detected electron microscopically in cutaneous fibropapillomas of a giraffe (Giraffa camelopardalis) and a sable antelope (Hippotragus niger). The virus particles measured 45 nm in diameter. Histopathologically, the lesions showed histopathological features similar to those of equine sarcoid as well as positive immunoperoxidase-staining of tissue sections for papillomavirus antigen. Polymerase chain reaction (PCR) detected bovine papillomavirus (BPV) DNA. Bovine papillomavirus-1 was characterised by real-time PCR in the sable and giraffe, and cloning and sequencing of the PCR product revealed a similarity to BPV-1. As in the 1st giraffe, the lesions from a 2nd giraffe revealed locally malignant pleomorphism, possibly indicating the lesional end-point of papilloma infection. Neither virus particles nor positively staining papillomavirus antigen could be demonstrated in the 2nd giraffe but papillomavirus DNA was detected by real-time PCR which corresponded with BPV-1 and BPV-2.
Genetic dissection of growth, wood basic density and gene expression in interspecific backcrosses of Eucalyptus grandis and E. urophylla
Kullan Anand Raj,van Dyk Maria M,Hefer Charles A,Jones Nicoletta
BMC Genetics , 2012, DOI: 10.1186/1471-2156-13-60
Abstract: Background F1 hybrid clones of Eucalyptus grandis and E. urophylla are widely grown for pulp and paper production in tropical and subtropical regions. Volume growth and wood quality are priority objectives in Eucalyptus tree improvement. The molecular basis of quantitative variation and trait expression in eucalypt hybrids, however, remains largely unknown. The recent availability of a draft genome sequence (http://www.phytozome.net) and genome-wide genotyping platforms, combined with high levels of genetic variation and high linkage disequilibrium in hybrid crosses, greatly facilitate the detection of quantitative trait loci (QTLs) as well as underlying candidate genes for growth and wood property traits. In this study, we used Diversity Arrays Technology markers to assess the genetic architecture of volume growth (diameter at breast height, DBH) and wood basic density in four-year-old progeny of an interspecific backcross pedigree of E. grandis and E. urophylla. In addition, we used Illumina RNA-Seq expression profiling in the E. urophylla backcross family to identify cis- and trans-acting polymorphisms (eQTLs) affecting transcript abundance of genes underlying QTLs for wood basic density. Results A total of five QTLs for DBH and 12 for wood basic density were identified in the two backcross families. Individual QTLs for DBH and wood basic density explained 3.1 to 12.2% of phenotypic variation. Candidate genes underlying QTLs for wood basic density on linkage groups 8 and 9 were found to share trans-acting eQTLs located on linkage groups 4 and 10, which in turn coincided with QTLs for wood basic density suggesting that these QTLs represent segregating components of an underlying transcriptional network. Conclusion This is the first demonstration of the use of next-generation expression profiling to quantify transcript abundance in a segregating tree population and identify candidate genes potentially affecting wood property variation. The QTLs identified in this study provide a resource for identifying candidate genes and developing molecular markers for marker-assisted breeding of volume growth and wood basic density. Our results suggest that integrated analysis of transcript and trait variation in eucalypt hybrids can be used to dissect the molecular basis of quantitative variation in wood property traits.
Radio Detection of SN 1986E in NGC 4302
M. J. Montes,S. D. Van Dyk,K. W. Weiler,R. A. Sramek,N. Panagia
Physics , 1997, DOI: 10.1086/310694
Abstract: Radio observations of SN 1986E have shown a clear detection of emission at 6 cm wavelength about 8 months after optical discovery. Combined with a number of new upper limits and a study of the possible models, it appears that SN 1986E was probably a fairly normal Type IIL supernova, somewhat similar to SN 1980K, with radio emission at roughly expected levels. This detection continues the correlation between radio detection and late time optical emission.
Galactic Evolved Massive Stars Discovered by Their Infrared Emission
A. P. Marston,J. Mauerhan,S. Van Dyk,M. Cohen,P. Morris
Physics , 2013,
Abstract: Determining the Galactic distribution and numbers of massive stars, such as Wolf-Rayet stars (WRs), is hampered by intervening Galactic or local circumstellar dust obscuration. In order to probe such regions of the Galaxy we can use infrared observations, which provide a means for finding such hidden populations through the dust. The availability of both 2MASS and Spitzer/GLIMPSE large-scale survey data provides infrared colours from 1.25 to 8$\mu$m for a large fraction of the inner Galactic plane. In 2005 we initiated a pilot study of the combined set of infrared colours for two GLIMPSE fields and showed that WRs typically occupy a sparsely populated region of the colour space. We followed up 42 of our WR candidates spectroscopically in the near-infrared, and with limited additional observations of some of these candidates in the optical. Six new WRs, four late-type WN and two late-type WC stars, were discovered as a result. Of the remaining $\sim$86% of the sample, five appear to be O-type stars. 21 stars are likely of type Be, and 10 stars appear to be of late-type, or possibly young stellar objects, which have "contaminated" the infrared color space. The survey is generally unbiased towards clusters or field stars, and the new WRs found are in both the field and in and around the RCW 49 region (including cluster Westerlund 2). In this work, and in our other recent work, we show that the infrared broad-band colours to be the most efficient means of identifying (particularly, dust-obscured) candidate massive stars, notably WRs.
Radio Supernovae as Distance Indicators
K. W. Weiler,S. D. Van Dyk,M. J. Montes,N. Panagia,R. A. Sramek
Physics , 1998, DOI: 10.1086/305723
Abstract: Long-term monitoring of the radio emission from supernovae with the Very Large Array (VLA) shows that the radio ``light curves'' evolve in a systematic fashion with a distinct peak flux density (and thus, in combination with a distance, a peak spectral luminosity) at each frequency and a well-defined time from explosion to that peak. Studying these two quantities at 6 cm wavelength, peak spectral luminosity (L_{6 cm peak}) and time after explosion date (t_0) to reach that peak (t_{6 cm peak} - t_0), we find that they appear related. In particular, based on two objects, Type Ib supernovae may be approximate radio ``standard candles'' with a 6 cm peak luminosity L_{6 cm peak} \approx 19.9 X 10^{26} erg s^{-1} Hz^{-1}; also based on two objects, Type Ic supernovae may be approximate radio ``standard candles'' with a 6 cm peak luminosity L_{6 cm peak} \approx 6.5 X 10^{26} erg s^{-1} Hz^{-1}; and, based on twelve objects, Type II supernovae appear to obey a relation L_{6 cm peak} \simeq 5.5 X 10^{23} (t_{6 cm peak} - t_0)^{1.4} erg s^{-1} Hz^{-1}, with time measured in days. If these relations are supported by further observations, they provide a means for determining distances to supernovae, and thus to their parent galaxies, from purely radio continuum observations.
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