Resistance of Grapevine Rootstocks to Meloidogyne incognita under Field Conditions

Resistance of grapevine rootstocks to root-knot nematodes (Meloidogyne incognita) was studied in field trials. Resistance was found to be adequately expressed by the degree of galling. A highly significant positive correlation exists between nematode populations in the soil as well as nematode reproduction and galling, while grapevine growth and yield were negatively related to the degree of infestation. However, information regarding rootstock tolerance and intolerance (sensitivity) was not considered reliable. It was further shown that a susceptible scion would not lower the resistance of the rootstock involved. Based on their rate of galling, rootstocks Ramsey, 99 Richter PS, Dogridge, Freedom, Harmony and 101-14 Mgt are resistant while Jacquez, 140 Ruggeri, Grezot-1, Maleque 44-53 and Constantia Metallica are susceptible

Chemical Control of Root-Knot Nematodes in Established Vineyards

Chemical control of root-knot nematodes (Meloidogyne spp.) in established vineyards was investigated. A liquid soil fumigant (1,3-dichloropropene) and four systemic (nonfumigant) nematicides in granular form, viz. aldicarb, carbofuran, oxamyl and fenamiphos were applied as soil treatments during bud burst and after harvest. Significant average yield and cane mass increases were recorded during the three years following split treatment at bud burst with aldicarb and oxamyl and when aldicard was applied as a single treatment after harvest

Cognitive radio DAB MAC protocol performance using a CR specific simulator and software defined radio

Abstract: With the constant advances in wireless technology, radio spectrum has become a very scarce resource. Cognitive Radio (CR) has emerged as a viable way to deal with our inefficient use of the radio spectrum by utilizing unused spectrum holes or white spaces, as they are referred to. Using Software Defined Radio (SDR) we are able to realize CRs and their unique properties. Most of the research that has been done on CR protocols has been based on analytical assessments and simulations using non-CR specific network simulators. In this paper we code and compare two existing CR specific Medium Access Control (MAC) protocols using a CR specific simulator. We then prototype the chosen protocols using the Universal Software Radio Peripheral (USRP). This allows us to see how close the simulated performance results come to those actually achieved in a real prototype

High resolution spectroscopy of single NV defects coupled with nearby 13^{13}C nuclear spins in diamond

We report a systematic study of the hyperfine interaction between the electron spin of a single nitrogen-vacancy (NV) defect in diamond and nearby $^{13}$C nuclear spins, by using pulsed electron spin resonance spectroscopy. We isolate a set of discrete values of the hyperfine coupling strength ranging from 14 MHz to 400 kHz and corresponding to $^{13}$C nuclear spins placed at different lattice sites of the diamond matrix. For each lattice site, the hyperfine interaction is further investigated through nuclear spin polarization measurements and by studying the magnetic field dependence of the hyperfine splitting. This work provides informations that are relevant for the development of nuclear-spin based quantum register in diamond.Comment: 8 pages, 5 figure

Polarization-selective excitation of N-V centers in diamond

The nitrogen-vacancy (N-V) center in diamond is promising as an electron spin qubit due to its long-lived coherence and optical addressability. The ground state is a spin triplet with two levels ($m_s = \pm 1$) degenerate at zero magnetic field. Polarization-selective microwave excitation is an attractive method to address the spin transitions independently, since this allows operation down to zero magnetic field. Using a resonator designed to produce circularly polarized microwaves, we have investigated the polarization selection rules of the N-V center. We first apply this technique to N-V ensembles in [100] and [111]-oriented samples. Next, we demonstrate an imaging technique, based on optical polarization dependence, that allows rapid identification of the orientations of many single N-V centers. Finally, we test the microwave polarization selection rules of individual N-V centers of known orientation

The quantitative determination and some values of dimethyl sulphide in white table wines

A gaschromatographic headspace method has been developed for the quantitative determination of dimethyl sulphide (DMS) in wines. The standard deviation of the method was in the order of 6%.Application of the method to the analysis of several white wines showed DMS values which varied from O to over 400 µg/1. From analytical data it appeared that DMS developed in the bottle and could as such possibly contribute to bottle bouquet. It was found that maturecl Riesling wines had particularly high concentrations of DMS.Die quantitative Bestimmung von Dimethylsulfid in weißen Tafelweinen sowieeinige Angaben über seine KonzentrationFür die quantitative Bestimmung von Dimethylsulfid (DMS) in Wein wurde unter Verwendung der „headspace"-Technik und von Dichlormethan als Standard eine gaschromatographische Methode entwickelt. Die Genauigkeit der Methode liegt bei einer Standardabweichung von 6%. Bei der Anwendung der Methode auf eine Reihe von Weißweinen wurden DMS-Werte zwischen O und über 400 µg/l ermittelt. DMS scheint sich während der Ausreifung des Weines in der Flasche zu entwickeln und könnte zum sogenannten Lagerungsbukett beitragen. Besonders hohe DMS-Konzentrationen wurden in älteren Riesling-Weinen festgestellt

Geregtelike geneeskunde : die multidissiplinêre benadering

Ek vra u vergunning om by hierdie geleentheid enkele woorde van dank en waardering uit te spreek. Eerstens my dank aan die Universiteit van Pretoria vir die vertroue in my gestel deur my in hierdie verantwoordelike pos aan te stel. Ek wil graag onderneem om steeds my bes te doen om op 'n verantwoordelike en bevredigende wyse aan die hoe eise en verwagtinge wat ek weet wat gestel mag word, te voldoen.Digitised by the Department of Library Services in support of open access to information, University of Pretoria, 202

Energy levels and decoherence properties of single electron and nuclear spins in a defect center in diamond

The coherent behavior of the single electron and single nuclear spins of a defect center in diamond and a 13C nucleus in its vicinity, respectively, are investigated. The energy levels associated with the hyperfine coupling of the electron spin of the defect center to the 13C nuclear spin are analyzed. Methods of magnetic resonance together with optical readout of single defect centers have been applied in order to observe the coherent dynamics of the electron and nuclear spins. Long coherence times, in the order of microseconds for electron spins and tens of microseconds for nuclear spins, recommend the studied system as a good experimental approach for implementing a 2-qubit gate.Comment: 4 pages, 4 figure