1,379 research outputs found

    No evidence of an 11.16 MeV 2+ state in 12C

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    An experiment using the 11B(3He,d)12C reaction was performed at iThemba LABS at an incident energy of 44 MeV and analyzed with a high energy-resolution magnetic spectrometer, to re-investigate states in 12C published in 1971. The original investigation reported the existence of an 11.16 MeV state in 12C that displays a 2+ nature. In the present experiment data were acquired at laboratory angles of 25-, 30- and 35- degrees, to be as close to the c.m. angles of the original measurements where the clearest signature of such a state was observed. These new low background measurements revealed no evidence of the previously reported state at 11.16 MeV in 12C

    The case of cholera preparedness, response and prevention in the SADC region: A need for proactive and multi-level communication and co-ordination

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    In this paper the authors seek to identify the most appropriate model for a regional co-ordination mechanism for cholera preparedness, response and prevention. The qualitative mixed-method data collection approach that was followed revealed the need for alternative solutions, including a socio-political understanding of cholera responses at different levels of scale and at different stages of an outbreak. Important areas that need to be understood include the multiplicity of actors and the complexity of their interaction, the importance of building local capacity, the need for varying responses at different levels of scale, the need for improved inter- and intra-country co-ordination and information exchange, the importance of cultural belief systems and the impact of the media on the response to cholera outbreaks. Ultimately, despite the proposed co-ordinating role that the Southern African Development Community (SADC) can play in a regional cholera response effort, the onus remains on states to build capacity at the local level and to capacitate local communities to drive response efforts semi-autonomously.Keywords: Cholera prevention, preparedness and response, socio-political understanding of cholera, socio-cultural understanding of cholera, transboundary disease, Southern African Development Community (SADC), choler

    Wavelet signatures of KK-splitting of the Isoscalar Giant Quadrupole Resonance in deformed nuclei from high-resolution (p,p') scattering off 146,148,150^{146,148,150}Nd

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    The phenomenon of fine structure of the Isoscalar Giant Quadrupole Resonance (ISGQR) has been studied with high energy-resolution proton inelastic scattering at iThemba LABS in the chain of stable even-mass Nd isotopes covering the transition from spherical to deformed ground states. A wavelet analysis of the background-subtracted spectra in the deformed 146,148,150Nd isotopes reveals characteristic scales in correspondence with scales obtained from a Skyrme RPA calculation using the SVmas10 parameterization. A semblance analysis shows that these scales arise from the energy shift between the main fragments of the K = 0, 1 and K = 2 components.Comment: 7 pages, 6 figure

    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

    Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

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    Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 <pT,assoc<pT,trig< < p_{\rm{T}, assoc} < p_{\rm{T}, trig} < 5.0 GeV/cc is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range η<0.9|\eta|<0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

    Effective Rheology of Bubbles Moving in a Capillary Tube

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    We calculate the average volumetric flux versus pressure drop of bubbles moving in a single capillary tube with varying diameter, finding a square-root relation from mapping the flow equations onto that of a driven overdamped pendulum. The calculation is based on a derivation of the equation of motion of a bubble train from considering the capillary forces and the entropy production associated with the viscous flow. We also calculate the configurational probability of the positions of the bubbles.Comment: 4 pages, 1 figur

    Cross-sections for nuclide production in 56Fe target irradiated by 300, 500,750, 1000, 1500, and 2600 MeV protons compared with data on hydrogen target irradiation by 300, 500, 750, 1000, and 1500 MeV/nucleon 56Fe ions

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    Cross-sections for radioactive nuclide production in 56Fe(p,x) reactions at 300, 500, 750, 1000, 1500, and 2600 MeV were measured using the ITEP U-10 proton accelerator. In total, 221 independent and cumulative yields of products of half-lives from 6.6 min to 312 days have been obtained via the direct-spectrometry method. The measured data have been compared with the experimental data obtained elsewhere by the direct and inverse kinematics methods and with calculations by 15 codes, namely: MCNPX (INCL, CEM2k, BERTINI, ISABEL), LAHET (BERTINI, ISABEL), CEM03 (.01, .G1, .S1), LAQGSM03 (.01, .G1, >.S1), CASCADE-2004, LAHETO, and BRIEFF. Most of our data are in a good agreement with the inverse kinematics results and disprove the results of some earlier activation measurements that were quite different from the inverse kinematics measurements. The most significant calculation-to-experiment differences are observed in the yields of the A<30 light nuclei, indicating that further improvements in nuclear reaction models are needed, and pointing out as well to a necessity of more complete measurements of such reactions.Comment: 53 pages, 9 figures, 6 tables, only pdf file, submitted to Phys. Rev.

    An Educator Approach towards Learner Discipline as a Prerequisite in Dealing with Learner Misconduct

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    Daar is deur die eeue heen gedebatteer oor die effektiwiteit van verskillende dissipline-metodes. Twee denkrigtings wat die impak van leerderdissipline beïnvloed, word bespreek. Die reformatief-pedagogiese denkrigting (gegrond op Christelike beginsels) word met die humanistiese denkrigting vergelyk. Die bespreking van beide die denkrigtings het ten doel om die mees funksionele hanteringsmetodes van leerderwangedrag te bepaal.Die vraag ontstaan nou hoe die opvoeder leerderwangedrag vanuit ’n onderwysregtelike raamwerk kan benader as hy/sy eintlik aan ’n reformatief-pedagogiese denkrigting glo. Daar sal veral op die rol van die opvoeder in die hantering van leerderwangedrag vanuit beide denkrigtings gefokus word. Die rol van die opvoeder sal ook aan die hand van Suid-Afrikaanse wetgewing bespreek word. Die algemene persepsie van die Suid-Afrikaanse wetgewing is dat leer nie sal kan plaasvind as leerders hulle aan leerderwangedrag skuldig maak nie. Die rol van die opvoeder in die gebruik van dissiplinemetodes wat leerderwangedrag bevorder, word ondersoek.Die vraag word deur middel van empiriese bevindinge wat die opvoeder-leerderverhouding ondersoek het, beantwoord. Die bevindinge van die literatuuroorsig asook die empiriese ondersoek sal vanuit die reformatories-pedagogiese en humanistiese denkrigting geëvalueer word. Aanbevelings word veral met betrekking tot vakkennis en die benadering van die opvoeder gemaak

    Municipal sludge as source of nitrogen and phosphorus in perennial pasture Eragrostis curvula production: Agronomic benefits and environmental impacts

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    Land application of sludge has been shown to improve soil properties and aid crop growth, but the possibility of constituent nutrients such as nitrogen and phosphorus reaching environmentally toxic levels has caused governing authorities to set limits to how much sludge can be applied to agronomic land. The high nitrogen utilisation potential of pasture grasses suggests that more sludge can be used in this cropping system without the risk of excess nitrates. This study investigates the effect of exceeding the South African sludge application limit on hay yield, soil nitrates and phosphorus. Field plots were arranged in a complete block design comprising 4 replications of 4 treatments planted to Eragrostis curvula. The treatments consisted of 0, 4, 8 and 16 Mg∙ha-1 anaerobically digested sludge. Soil samples were collected before treatment application and at the end of each growing season for N, P, NO3-, NH4+, and Bray-1P analyses. Plant samples were collected at flowering stage for hay yield and N and P uptake determination. Statistical analyses were conducted using analysis of variance (ANOVA) and general linear model (GLM) procedures of Windows SAS 9.0 to evaluate the effect of sludge application rates on hay yield. Results over 4 growing seasons indicate that exceeding the recommended limit increased hay yield by 4% in a dry season (11.7 vs. 12.36 Mg∙ha-1) and by 16% in a wet season (14.19 vs. 17.31 Mg∙ha-1) and also increased nitrogen uptake by 15%. Sludge applied at double the recommended limit did not cause the accumulation of nitrate and ammonium in the soil, however, both total and Bray-1P were doubled. The study shows that the potential long-term environmental risk of doubling the sludge application rate norm would be from labile P accumulation in the soil profile despite a sludge P:Fe molar ratio of less than unity.Keywords: sludge, Eragrostis curvula, nitrogen, phosphorus, leachin
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