23 research outputs found

    Train schedule delays leading to overcrowding, injuries and fatalities

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    Abstract: Rail industry in South Africa is facing a dilemma in connection with trains overcrowding causing injuries and fatalities. This paper emphasized this topic analysis to reach the understanding of the problem to an eventual solution that will benefit both the train user and the operator. One of the priority insights look was at the annual train planned schedule versus the actual state of trains given to run. The overall objective of the paper’s study was to analyze the existing train schedule that is currently in use and whether addressing the needs of the commuter. The paper highlighted that the found-out train planned schedule are not always met due to technical issues. The paper also investigated the number of healthy trains versus the commuter demand per peak, because operationally fit trains are required to avoid service distraction that can lead to overcrowding of trains

    Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

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    New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure

    The MeerKAT telescope as a pulsar facility: System verification and early science results from MeerTime

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    We describe system verification tests and early science results from the pulsar processor (PTUSE) developed for the newly commissioned 64-dish SARAO MeerKAT radio telescope in South Africa. MeerKAT is a high-gain ( ) low-system temperature ( ) radio array that currently operates at 580–1 670 MHz and can produce tied-array beams suitable for pulsar observations. This paper presents results from the MeerTime Large Survey Project and commissioning tests with PTUSE. Highlights include observations of the double pulsar , pulse profiles from 34 millisecond pulsars (MSPs) from a single 2.5-h observation of the Globular cluster Terzan 5, the rotation measure of Ter5O, a 420-sigma giant pulse from the Large Magellanic Cloud pulsar PSR , and nulling identified in the slow pulsar PSR J0633–2015. One of the key design specifications for MeerKAT was absolute timing errors of less than 5 ns using their novel precise time system. Our timing of two bright MSPs confirm that MeerKAT delivers exceptional timing. PSR exhibits a jitter limit of whilst timing of PSR over almost 11 months yields an rms residual of 66 ns with only 4 min integrations. Our results confirm that the MeerKAT is an exceptional pulsar telescope. The array can be split into four separate sub-arrays to time over 1 000 pulsars per day and the future deployment of S-band (1 750–3 500 MHz) receivers will further enhance its capabilities

    The SARAO MeerKAT 1.3 GHz Galactic Plane Survey

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    We present the SARAO MeerKAT Galactic Plane Survey (SMGPS), a 1.3 GHz continuum survey of almost half of the Galactic Plane (251\deg l\le l \le 358\deg and 2\deg l\le l \le 61\deg at b1.5deg|b| \le 1.5\deg ). SMGPS is the largest, most sensitive and highest angular resolution 1 GHz survey of the Plane yet carried out, with an angular resolution of 8" and a broadband RMS sensitivity of \sim10--20 μ\mu Jy/beam. Here we describe the first publicly available data release from SMGPS which comprises data cubes of frequency-resolved images over 908--1656 MHz, power law fits to the images, and broadband zeroth moment integrated intensity images. A thorough assessment of the data quality and guidance for future usage of the data products are given. Finally, we discuss the tremendous potential of SMGPS by showcasing highlights of the Galactic and extragalactic science that it permits. These highlights include the discovery of a new population of non-thermal radio filaments; identification of new candidate supernova remnants, pulsar wind nebulae and planetary nebulae; improved radio/mid-IR classification of rare Luminous Blue Variables and discovery of associated extended radio nebulae; new radio stars identified by Bayesian cross-matching techniques; the realisation that many of the largest radio-quiet WISE HII region candidates are not true HII regions; and a large sample of previously undiscovered background HI galaxies in the Zone of Avoidance

    The 1.28 GHz MeerKAT DEEP2 Image

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    We present the confusion-limited 1.28 GHz MeerKAT DEEP2 image covering one qb » ¢ 68 FWHM primarybeam area with θ = 7 6 FWHM resolution and s = m - n 0.55 0.01 Jy beam 1 rms noise. Its J2000 center position α = 04h 13m 26 4, δ = −80° 00′ 00″ was selected to minimize artifacts caused by bright sources. We introduce the new 64-element MeerKAT array and describe commissioning observations to measure the primary-beam attenuation pattern, estimate telescope pointing errors, and pinpoint (u, v) coordinate errors caused by offsets in frequency or time. We constructed a 1.4 GHz differential source count by combining a power-law count fit to the DEEP2 confusion P(D) distribution from 0.25 to 10 μJy with counts of individual DEEP2 sources between 10 μJy and 2.5 mJy. Most sources fainter than S ∼ 100 μJy are distant star-forming galaxies (SFGs) obeying the far-IR/ radio correlation, and sources stronger than 0.25 μJy account for ∼93% of the radio background produced by SFGs. For the first time, the DEEP2 source count has reached the depth needed to reveal the majority of the star formation history of the universe. A pure luminosity evolution of the 1.4 GHz local luminosity function consistent with the Madau & Dickinson model for the evolution of SFGs based on UV and infrared data underpredicts our 1.4 GHz source count in the range -5 log Jy 4 [ ( )] S

    The SARAO MeerKAT 1.3 GHz Galactic Plane Survey

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    We present the SARAO MeerKAT Galactic Plane Survey (SMGPS), a 1.3 GHz continuum survey of almost half of the Galactic Plane (251○ ≤l ≤ 358○ and 2○ ≤l ≤ 61○ at |b| ≤ 1 5). SMGPS is the largest, most sensitive and highest angular resolution 1 GHz survey of the Plane yet carried out, with an angular resolution of 8″ and a broadband RMS sensitivity of ∼10–20 μJy beam−1. Here we describe the first publicly available data release from SMGPS which comprises data cubes of frequency-resolved images over 908–1656 MHz, power law fits to the images, and broadband zeroth moment integrated intensity images. A thorough assessment of the data quality and guidance for future usage of the data products are given. Finally, we discuss the tremendous potential of SMGPS by showcasing highlights of the Galactic and extragalactic science that it permits. These highlights include the discovery of a new population of non-thermal radio filaments; identification of new candidate supernova remnants, pulsar wind nebulae and planetary nebulae; improved radio/mid-IR classification of rare Luminous Blue Variables and discovery of associated extended radio nebulae; new radio stars identified by Bayesian cross-matching techniques; the realisation that many of the largest radio-quiet WISE H II region candidates are not true H II regions; and a large sample of previously undiscovered background H I galaxies in the Zone of Avoidance

    The MeerKAT Galaxy Cluster Legacy Survey: I. Survey overview and highlights

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    Please abstract in the article.The South African Radio Astronomy Observatory (SARAO), the National Research Foundation (NRF), the National Radio Astronomy Observatory, US National Science Foundation, the South African Research Chairs Initiative of the DSI/NRF, the SARAO HCD programme, the South African Research Chairs Initiative of the Department of Science and Innovation.http://www.aanda.orghj2022Physic

    The effect of gender and ethnic differences on the success of intervention programmes for the motor proficiency and self-concept of 7-9 year old DCD children

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    More boys than girls are diagnosed with DCD (Maldonadoo-Duran, 2002), while boys have a higher global (Davies & Brember, 1999) and physical self-concept (Crocker et al., 2000) than girls. However, no literature exists with regard to ethical differences. Teachers identified 201 potential DCD candidates. The Movement Assessment Battery for Children (Henderson & Sugden, 1992) identified 58 with DCD (36 boys and 22 girls). The Tennessee Self-Concept Scale (Child Form) (Fitts & Warren, 1996) and Child Anxiety Scale (Gillis, 1980) were administered to determine the children's self-concept and anxiety respectively. A four-group pretestposttest, with two follow-up tests was used. Children were randomly grouped into experimental groups (motor based intervention, self-concept enhancing intervention, integrated psycho-motor intervention and control group). A repeated measures ANOVA was used to determine interactions within the groups, independent t-tests to determine gender differences and a one-way ANOVA to determine differences between the ethnic groups. The self-concept of the girls in the psychological group improved moderately significantly (p=0.09) more than that of the boys, while the white children's motor proficiency (motor based intervention group) improved significantly more than the black children's. These differences were, however, not large enough to justify different intervention programmes for different ethnic groups and genders. Keywords: Gender; Ethnic; Race; Children; DCD. South African Journal for Research in Sport, Physical Education and Recreation Vol. 29 (1) 2007: pp. 113-12

    Ethical considerations in kinderkinetics research

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    There are certain ethical considerations that should be taken into account when research that involves young children, is planned. The purpose of this study was to determine certain pitfalls that Kinderkineticists experience while doing research involving young children. Out of this study it is clear that there are many guidelines that need to be followed when research involving young children is conducted. The major guideline that is mentioned is the necessity of informed consent. The guidelines found in the medical research council are stipulated in this article. Certain pitfalls that Kinderkineticists then experience in the research process are also mentioned. One of the major problems in South Africa is the multicultural nature of the land with eleven official languages. This leads to a language barrier during the research process. In conclusion it can be said that good planning of the research project, to foresee the pitfalls are very important, in order to have a successful research project. African Journal for Physical, Health Education, Recreation and Dance Vol. 13 (1) 2007: pp. 103-11
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