Browsing by Subject "survey"

Now showing 1 - 11 of 11
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    Open Access
    Accurate Recovery of H i Velocity Dispersion from Radio Interferometers
    (2017) Ianjamasimanana, R; Blok, W J G de; Heald, George H
    Gas velocity dispersion measures the amount of disordered motion of a rotating disk. Accurate estimates of this parameter are of the utmost importance because the parameter is directly linked to disk stability and star formation. A global measure of the gas velocity dispersion can be inferred from the width of the atomic hydrogen (H I) 21 cm line. We explore how several systematic effects involved in the production of H I cubes affect the estimate of H I velocity dispersion. We do so by comparing the H I velocity dispersion derived from different types of data cubes provided by The H I Nearby Galaxy Survey. We find that residual-scaled cubes best recover the H I velocity dispersion, independent of the weighting scheme used and for a large range of signal-to-noise ratio. For H I observations, where the dirty beam is substantially different from a Gaussian, the velocity dispersion values are overestimated unless the cubes are cleaned close to (e.g., ˜1.5 times) the noise level.
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    An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013
    (2014) Robinson, William M L; Butterworth, Doug S
    The results from the small scale hydroacoustic surveys of the abundance of anchovy around Robben and Dassen islands over the 2009-2013 period are analysed under the assumption of a Gaussian form for the trends in density at each island over the course of the winter months. Based primarily on AICc, the model selected from amongst a number of variants has the same trend in abundance with year for the two islands, compatible with the assumption used by Robinson (2013) in his GLM analysis of the impact of closures to pelagic fishing around these islands on penguin recovery, though the data have limited power to distinguish deviations from that assumption. The abundance estimates from the island surveys, though compatible also with the May recruitment survey trends, show appreciably larger variance. This raises the question of whether these small scale surveys merit continuation, unless it is possible to increase their frequency considerably during the winter months each year to improve the overall precision of the integrals over local abundance which they can provide.
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    Open Access
    DOT4D Open Textbook Landscape Survey Report: University of Cape Town
    (Digital Open Textbooks for Development, 2021-07) Masuku, Bianca
    The Digital Open Textbooks for Development (DOT4D) project in the Centre for Innovation in Learning and Teaching at the University of Cape Town aims to better understand the affordances of open textbook publishing. This report presents findings from the DOT4D landscape survey which served to capture the institutional open textbook publishing terrain in order to gain a sense of current open textbook production and publication activity taking place within the university.
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    Enteral feeding practices in preterm infants in South Africa
    (Health and Medical Publishing Group, 2013) Raban, M S; Joolay, Y; Horn, A R; Harrison, M C
    Background: Optimal feeding regimens in babies weighing <1 000 g have not been established, and wide variations occur. In South Africa (SA) this situation is complicated by varied resource constraints. Objective: To determine the preterm enteral feeding practices of paediatricians in SA. Methods: We invited 288 paediatricians to participate in a cross-sectional web-based survey. Results. We received responses from 31.2% of the paediatricians; 43.6% were from the state sector and 56.4% from the private sector. Most participants worked in medium-sized neonatal units with 6 - 10 beds. The proportions commencing feeds within the first 24 hours were 24% in infants of <25 weeks’ gestational age, 36% in infants 25 - 27 weeks, and 65% in infants 28 - 31 weeks. Feed volumes were routinely advanced daily in 47% of infants <25 weeks, 68% of infants 25 - 27 weeks, and 90% of infants 28 - 31 weeks. Forty-five per cent of infants <25 weeks received continuous intragastric feeds, while 50% of those in the 28 - 31 weeks group were on 3-hourly bolus feeds. The majority of the participants targeted full enteral feeds of 161 - 180 ml/kg/d, 66.7% had access to donor milk, and 77% used breastmilk fortifier. Conclusion: This is the first study to survey feeding practices in SA. The survey did not highlight differences in feeding practices among paediatricians. These data could be valuable in the design of local collaborative trials to determine optimal feeding strategies.
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    HI in group interactions: HCG 44
    (2017) Hess, Kelley M; Cluver, M E; Yahya, Sahba; Leisman, Lukas; Serra, Paolo; Lucero, Danielle M; Passmoor, Sean S; Carignan, Claude
    Extending deep observations of the neutral atomic hydrogen (H I) to the environment around galaxy groups can reveal a complex history of group interactions which is invisible to studies that focus on the stellar component. Hickson Compact Group 44 (HCG 44) is a nearby example, and we have combined H I data from the Karoo Array Telescope, Westerbork Synthesis Radio Telescope, and Arecibo Legacy Fast ALFA survey, in order to achieve high column density sensitivity (N _{H {I}}
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    OER use in the Global South: A baseline survey of higher education instructors
    (African Minds, International Development Research Centre & Research on Open Educational Resources for Development, 2017-10-11) de Oliviera Neto, Jose Dutra; Pete, Judith; Daryono, Daryono; Cartmill, Tess; Cheryl Hodgkinson-Williams; Patricia Arinto
    The research presented here provides baseline data regarding the use of Open Educational Resources (OER) by higher education instructors in the Global South (South America, Sub-Saharan Africa, and South and Southeast Asia). It does so while attending to how such activity (or inactivity) is differentiated across continental regions and associated countries. The chapter addresses two questions: what proportion of instructors in the Global South have used OER, and which variables may account for different OER usage rates between respondents? This is done by examining which variables – such as gender, age, technological access and digital proficiency – seem to influence OER use rates, thereby allowing the authors to gauge which are the most important for instructors in their respective contexts. This study is based on a quantitative research survey taken by 295 randomly selected instructors at 28 higher education institutions in nine countries (Brazil, Chile, Colombia; Ghana, Kenya, South Africa; India, Indonesia, Malaysia). The 30-question survey addressed the following themes: personal demographics, infrastructure access, institutional environment, instructor attitudes and open licensing. Survey responses were correlated for analysis with respondents’ answers to the key question of the survey: whether they had ever used OER or not. Findings indicate that 51% of respondents have used OER, a rate slightly differentiated by region: 49% in South America, 46% in Sub-Saharan Africa and 56% in South and Southeast Asia. A number of variables were associated with varying levels of OER use rates – such as instructors’ country of habitation (and its gross domestic product per capita), level of digital proficiency, educational qualification, institutional position and attitude to education – while many others were not, such as instructors’ gender, age or perception of their institutions’ OER-related policies.
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    Primary health eye care knowledge among general practitioners working in the Cape Town Metropole
    (South African Academy of Family Practice, 2011) Van Zyl, L; Fernandes, N; Rogers, G; Du Toit, N
    Aim: The main purpose of this study was to determine whether general practitioners (GPs) in the Cape Town metropole have sufficient knowledge to diagnose and treat primary care ophthalmic conditions correctly, and to assess their own perceptions of their levels of knowledge. Secondary objectives included identifying the need for courses to improve the ophthalmic knowledge of GPs and assessing whether there is a need to revise the undergraduate curriculum in ophthalmology in general. Method: A cross-sectional survey was done. A questionnaire of 10 primary care level ophthalmology questions, including a self-assessment section, was sent to each of 140 randomly chosen GPs in Cape Town. Results: A response rate of 79.2% was obtained. Respondents included graduates from all eight medical schools in South Africa. Most of the responding GPs were practising for more than 10 years (78.2%). The mean test score was 52.5% (standard deviation [SD]: 22.2). The mean self-rating was 51.9% (SD: 14.5). There was no statistically significant difference between the test score and the self-rating score (p = 0.5840). Responding GPs felt that there is a need for ophthalmology up-skilling courses and 99.9% of them would attend such courses. Also, 82% of GPs felt that primary care doctors, not optometrists, should deliver primary eye care. Conclusion: GPs appear to lack sufficient knowledge to manage primary health eye care problems, presumably due to a lack of adequate training in the field. Clinical up-skilling courses are needed to improve core knowledge in ophthalmology.
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    Primary health eye care knowledge among general practitioners working in the Cape Town Metropole
    (2011) Van Zyl, L M; Fernandes, N; Rogers, G; Du Toit, N
    Aim: The main purpose of this study was to determine whether general practitioners (GPs) in the Cape Town metropole have sufficient knowledge to diagnose and treat primary care ophthalmic conditions correctly, and to assess their own perceptions of their levels of knowledge. Secondary objectives included identifying the need for courses to improve the ophthalmic knowledge of GPs and assessing whether there is a need to revise the undergraduate curriculum in ophthalmology in general. Method: A cross-sectional survey was done. A questionnaire of 10 primary care level ophthalmology questions, including a self-assessment section, was sent to each of 140 randomly chosen GPs in Cape Town. Results: A response rate of 79.2% was obtained. Respondents included graduates from all eight medical schools in South Africa. Most of the responding GPs were practising for more than 10 years (78.2%). The mean test score was 52.5% (standard deviation [SD]: 22.2). The mean self-rating was 51.9% (SD: 14.5). There was no statistically significant difference between the test score and the self-rating score (p = 0.5840). Responding GPs felt that there is a need for ophthalmology up-skilling courses and 99.9% of them would attend such courses. Also, 82% of GPs felt that primary care doctors, not optometrists, should deliver primary eye care. Conclusion: GPs appear to lack sufficient knowledge to manage primary health eye care problems, presumably due to a lack of adequate training in the field. Clinical up-skilling courses are needed to improve core knowledge in ophthalmology.
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    The LOFAR Two-metre Sky Survey: I. Survey description and preliminary data release⋆
    (2017) Shimwell, T W; Röttgering, H J A; Best, P N; Williams, W L; Dijkema, T J; de Gasperin, F; Hardcastle, M J; Heald, G H; Hoang, D N; Horneffer, A; Intema, H; Mahony, E K; Mandal, S; Mechev, A P; Morabito, L; Oonk, J B R; Rafferty, D; Retana-Montenegro, E; Sabater, J; Tasse, C; van Weeren, R J; BrYggen, M; Brunetti, G; Chyży, K T; Conway, J E; Haverkorn, M; Jackson, N; Jarvis, M J; McKean, J P; Miley, G K; Morganti, R; White, G J
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    The VMC survey: I. strategy and first data
    (2011) Cioni, M- R L; Clementini, G; Girardi, L; Guandalini, R; Gullieuszik, M; Miszalski, B; Moretti, M-I; Ripepi, V; Rubele, S; Bagheri, G; Bekki, K; Cross, N; de Blok, W J G; de Grijs, R; Emerson, J P; Evans, C J; Gibson, B; Gonzales-Solares, E; Groenewegen, M A T; Irwin, M; Ivanov, V D; Lewis, J; Marconi, M; Marquette, J-B; Mastropietro, C; Moore, B; Napiwotzki, R; Naylor, T; Oliveira, J M; Read, M; Sutorius, E; van Loon, J Th
    Context. The new VISual and Infrared Telescope for Astronomy (VISTA) has started operations. Over its first five years it will be collecting data for six public surveys, one of which is the near-infrared YJK(s) VISTA survey of the Magellanic Clouds system (VMC). This survey comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud, the Magellanic Bridge connecting the two galaxies and two fields in the Magellanic Stream. Aims. This paper provides an overview of the VMC survey strategy and presents first science results. The main goals of the VMC survey are the determination of the spatially-resolved star-formation history and the three-dimensional structure of the Magellanic system. The VMC survey is therefore designed to reach stars as faint as the oldest main sequence turn-off point and to constrain the mean magnitude of pulsating variables such as RR Lyrae stars and Cepheids. This paper focuses on observations of VMC fields in the LMC obtained between November 2009 and March 2010. These observations correspond to a completeness of 7% of the planned LMC fields. Methods. The VMC data are comprised of multi-epoch observations which are executed following specific time constraints. The data were reduced using the VISTA Data Flow System pipeline with source catalogues, including astrometric and photometric corrections, produced and made available via the VISTA Science Archive. The VMC data will be released to the astronomical community following the European Southern Observatorys Public Survey policy. The analysis of the data shows that the sensitivity in each wave band agrees with expectations. Uncertainties and completeness of the data are also derived. Results. The first science results, aimed at assessing the scientific quality of the VMC data, include an overview of the distribution of stars in colour-magnitude and colour-colour diagrams, the detection of planetary nebulae and stellar clusters, and the K-s band light-curves of variable stars. Conclusions. The VMC survey represents a tremendous improvement, in spatial resolution and sensitivity, on previous panoramic observations of the Magellanic system in the near-infrared, providing a powerful complement to deep observations at other wavelengths.
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    The void galaxy survey: photometry, structure and identity of void galaxies
    (2017) Beygu, B; Peletier, R F; Hulst, J M van der; Jarrett, T H; Kreckel, K; Weygaert, R van de; van Gorkom, J H; Aragon-Calvo, M A
    We analyse photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6 μm and 4.5 μm Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the Sloan Digital Sky Survey Data Release 7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from MB = -15.5 to -20, while at the 3.6 μm band their magnitudes range from M3.6 = -18 to -24. Their B-[3.6] colour and structural parameters indicate these are star-forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3 × 1010 M⊙. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sérsic indices are nearly all smaller than n = 2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.