Thermalization of a Lipkin-Meshkov-Glick model coupled to a bosonic bath

We derive a Lindblad master equation that approximates the dynamics of a Lipkin-Meshkov-Glick (LMG) model weakly coupled to a bosonic bath. By studying the time evolution of operators under the adjoint master equation we prove that, for large system sizes, these operators attain their thermal equilibrium expectation values in the long-time limit, and we calculate the rate at which these values are approached. Integrability of the LMG model prevents thermalization in the absence of a bath, and our work provides an explicit proof that the bath indeed restores thermalization. Imposing thermalization on this otherwise non-thermalizing model outlines an avenue towards probing the unconventional thermodynamic properties predicted to occur in ultracold-atom-based realizations of the LMG model.Comment: 10 pages, 3 figure

Quantification of Resveratrol in Different Parts of Solid Pinotage Winery Waste: Investigating the Variance Between Consecutive Harvests

Resveratrol is phenolic compound that is produced by several plant species as a protection mechanism against biotic and abiotic stress. Resveratrol is currently being investigated as nutraceutical supplement, and there is a market value for the compound. The aim of this work was to investigate, through consecutive harvests the variability of solid winery waste as a source of resveratrol as an antioxidant supplement.  In this study the different parts of Pinotage solid winery waste from a 2018 and 2019 harvests were investigated as a possible resveratrol source. From the comparison of the different sources over time it was found that the 2019 Pinotage stems contained a maximum of 73 ± 4.3 μg/g resveratrol. Variable resveratrol concentrations were noted between consecutive harvests, indicating a variability in productivity.  Furthermore, resveratrol distribution throughout the plant was variable, with the canes and stems having the highest concentrations. Nonetheless, it was concluded that Pinotage solid winery waste can be used as a possible source of resveratrol. The findings in this paper provide information about the extractable resveratrol and total phenolic content of different parts of Pinotage solid winery waste and the variability of resveratrol content both within the plant, and between harvests

Ammonia Concentrations of Musts of Different Grape Cultivars and Vineyards in the Stellenbosch Area

The ammonia concentrations of a large number of loads of grapes from different farms and of different cultivars were measured. Varietal differences were noted and statistical verifications made. Nine different cultivars were investigated. The average mean ammonia values for the cultivars varied from 54,9 to 148,l mg/(. Where enough loads from individual vineyards or growers were available, statistical differences were demonstrated. The conditions, treatment, and soil of the vines were shown to be reflected in the extremes by the juice ammonia concentrations. The use of these data is suggested as a means of assessing the vineyard's relative worth for winemaking purposes

Universal cooling dynamics towards a quantum critical point

We investigate the loss of adiabaticity when cooling a many-body quantum system from an initial thermal state towards a quantum critical point. The excitation density, which quantifies the degree of adiabaticity of the dynamics, is found to obey scaling laws in the cooling velocity as well as in the initial and final temperatures of the cooling protocol. The scaling laws are universal, governed by the critical exponents of the quantum phase transition. The validity of these statements is shown analytically for a Kitaev quantum wire coupled to Markovian baths, and subsequently argued to be valid under rather general conditions. Our results establish that quantum critical properties can be probed dynamically at finite temperature, without even varying the control parameter of the quantum phase transitions.Comment: 5+4 pages, 2+2 figures; companion paper to "Long-range Kitaev chain in a thermal bath: Analytic techniques for time-dependent systems and environments" by the same authors and submitted on the same da

Immunology for Clinicians: A ‘Trojan Horse’ approach

A South African website imparts basic immunology information to clinicians and other health care workers

Symptomatology and Anatomy of Stemgrooving (Legno Riccio) 1n the Grape Vine

External and anatomical differences between organs affected and unaffected by stemgrooving were studied on the wine grape cultivar Chenin blanc and the table grape cultivars Barlinka and Almeria. Cultivar susceptibility, graft transmissibility as well as the effect of the disease on the percentage of take and growth in: the nursery were studied. The probability of an association with other virus diseases was considered. Abnormal behaviour of the vascular cambium of infected vines gave rise to hypertrophy, hyperplasia, hypoplasia and parenchymatoses in the secondary xylem and phloem. In diseased tissues dift'erentiation of pbeDogen proceeded abnormally deep into the phloem rays. Graft transmission was detected anatomically within six months. The disease was found in all the vine growing districts of the Western Cape. Anatomical.studies showed that the disease had been present for many years. A negative effect on the percentage of t:'tKe and growth in the nursery was, recorded. A probable-relationship with corky bark was indicated anatomically and by indexing with LN33

Adiabatic quantum trajectories in engineered reservoirs

We analyze the efficiency of protocols for adiabatic quantum state transfer assisted by an engineered reservoir. The target dynamics is a quantum trajectory in the Hilbert space and is the fixed point of a time-dependent master equation. We specialize to quantum state transfer in a qubit and determine the optimal schedule for a class of time-dependent Lindblad equations. The speed limit on state transfer is extracted from a physical model of a qubit coupled to a reservoir, from which the Lindblad equation is derived in the Born-Markov limit. Our analysis shows that the resulting efficiency is comparable to the efficiency of the optimal unitary dynamics. Numerical studies indicate that reservoir-engineered protocols could outperform unitary protocols outside the regime of the Born-Markov master equation, namely, when correlations between the qubit and reservoir become relevant. Our study contributes to the theory of shortcuts to adiabaticity for open quantum systems and to the toolbox of protocols of the NISQ era.Comment: 14+7 pages, 7 figure

Retention in care for adolescents who were newly initiated on antiretroviral therapy in the Cape Metropole in South Africa

Long-term retention of adolescents aged 10-19 years on antiretroviral therapy (ART) is crucial to achieve viral load suppression. However, it is reported globally that adolescents have lower retention in care (RiC) on ART, compared with children and adults. Objectives: To determine the prevalence and predictors of RiC of adolescents over 2 years following initiation onto ART in public health facilities in the Metropole District Health Services of the Western Cape province in 2013. Methods: Data of 220 adolescent patients who were newly initiated on ART in 2013 were extracted from the provincial electronic database, and subjected to univariate and bivariate analyses using SPSS. Results: The rate of RiC post-initiation was low throughout the study period, that is, 68.6%, 50.5% and 36.4% at 4, 12 and 24 months, respectively