Physics behind the minimum of relative entropy measures for correlations

The relative entropy of a correlated state and an uncorrelated reference state is a reasonable measure for the degree of correlations. A key question is however which uncorrelated state to compare to. The relative entropy becomes minimal for the uncorrelated reference state that has the same one-particle density matrix as the correlated state. Hence, this particular measure, coined nonfreeness, is unique and reasonable. We demonstrate that for relevant physical situations, such as finite temperatures or a correlation enhanced orbital splitting, other choices of the uncorrelated state, even educated guesses, overestimate correlations.Comment: 4 pages, 1 figure, final version as to appear European Physical Journal

Dephasing in coherently-split quasicondensates

We numerically model the evolution of a pair of coherently split quasicondensates. A truly one-dimensional case is assumed, so that the loss of the (initially high) coherence between the two quasicondensates is due to dephasing only, but not due to the violation of integrability and subsequent thermalization (which are excluded from the present model). We confirm the subexponential time evolution of the coherence between two quasicondensates $\propto \exp [-(t/t_0)^{2/3}]$, experimentally observed by S. Hofferberth {\em et. al.}, Nature {\bf 449}, 324 (2007). The characteristic time $t_0$ is found to scale as the square of the ratio of the linear density of a quasicondensate to its temperature, and we analyze the full distribution function of the interference contrast and the decay of the phase correlation.Comment: revtex4, 9 pages, 8 figure

Fluctuations and stochastic processes in one-dimensional many-body quantum systems

We study the fluctuation properties of a one-dimensional many-body quantum system composed of interacting bosons, and investigate the regimes where quantum noise or, respectively, thermal excitations are dominant. For the latter we develop a semiclassical description of the fluctuation properties based on the Ornstein-Uhlenbeck stochastic process. As an illustration, we analyze the phase correlation functions and the full statistical distributions of the interference between two one-dimensional systems, either independent or tunnel-coupled and compare with the Luttinger-liquid theory.Comment: 4 pages (revtex4), 4 color figures. Text substantially rewritten, two figures adde

On two-temperature problem for harmonic crystals

We consider the dynamics of a harmonic crystal in $d$ dimensions with $n$ components,$d,n \ge 1$. The initial date is a random function with finite mean density of the energy which also satisfies a Rosenblatt- or Ibragimov-Linnik-type mixing condition. The random function converges to different space-homogeneous processes as $x_d\to\pm\infty$, with the distributions $\mu_\pm$. We study the distribution $\mu_t$ of the solution at time $t\in\R$. The main result is the convergence of $\mu_t$ to a Gaussian translation-invariant measure as $t\to\infty$. The proof is based on the long time asymptotics of the Green function and on Bernstein's `room-corridor' argument. The application to the case of the Gibbs measures $\mu_\pm=g_\pm$ with two different temperatures $T_{\pm}$ is given. Limiting mean energy current density is $- (0,...,0,C(T_+ - T_-))$ with some positive constant $C>0$ what corresponds to Second Law

Political branding: sense of identity or identity crisis? An investigation of the transfer potential of the brand identity prism to the UK Conservative Party

Brands are strategic assets and key to achieving a competitive advantage. Brands can be seen as a heuristic device, encapsulating a series of values that enable the consumer to make quick and efficient choices. More recently, the notion of a political brand and the rhetoric of branding have been widely adopted by many political parties as they seek to differentiate themselves, and this has led to an emerging interest in the idea of the political brand. Therefore, this paper examines the UK Conservative Party brand under David Cameron’s leadership and examines the applicability of Kapferer’s brand identity prism to political branding. This paper extends and operationalises the brand identity prism into a ‘political brand identity network’ which identifies the inter-relatedness of the components of the corporate political brand and the candidate political brand. Crucial for practitioners, this model can demonstrate how the brand is presented and communicated to the electorate and serves as a useful mechanism to identify consistency within the corporate and candidate political brands

Surgical exploration for penetrating neck trauma - an audit of results in 145 patients

BACKGROUND : Selective non-operative management (SNOM) is the current gold standard for the treatment of patients with penetrating neck trauma. The policy revolves around the liberal use of computed tomography angiography (CTA) in those patients who are haemodynamically stable, irrespective of the anatomical zone of injury, aiming at reducing the incidence of negative and non-therapeutic interventions and their potential complications. METHOD : A retrospective audit of results of patients who underwent immediate surgical exploration at the Chris Hani Baragwanath Academic Hospital in Soweto between January 2010 and December 2015 was performed. RESULTS : One-hundred and forty-five (145) patients, with a median age of 28 years (range 18-67 years), predominantly males (93.8%), underwent immediate exploration. Most injuries were caused by stab wounds (92.4%) and affected zone 2 (54.1%) on the left side of the neck (69.6%). The most common presentations were active haemorrhage (29.4%), shock (24.1%) and expanding haematoma (15.1%). A major vascular injury was found in 40%, and aero-digestive organ injury in 19.3%. The rate of negative-non-therapeutic exploration in this cohort was 4.1%. Complications were recorded in 7.6%, and the overall mortality was 9.6% secondary to early uncontrolled haemorrhage, sepsis and occlusive strokes. CONCLUSION : The utilisation of SNOM with strict criteria for selection of patients who require immediate surgical exploration versus investigations with CTA results in a low rate of non-therapeutic interventions.https://journals.co.za/journal/m.sajsam2024SurgerySDG-03:Good heatlh and well-bein

Resonant Thermoelectric Nanophotonics

Photodetectors are typically based either on photocurrent generation from electron–hole pairs in semiconductor structures or on bolometry for wavelengths that are below bandgap absorption. In both cases, resonant plasmonic and nanophotonic structures have been successfully used to enhance performance. Here, we show subwavelength thermoelectric nanostructures designed for resonant spectrally selective absorption, which creates large localized temperature gradients even with unfocused, spatially uniform illumination to generate a thermoelectric voltage. We show that such structures are tunable and are capable of wavelength-specific detection, with an input power responsivity of up to 38 V W^(–1), referenced to incident illumination, and bandwidth of nearly 3 kHz. This is obtained by combining resonant absorption and thermoelectric junctions within a single suspended membrane nanostructure, yielding a bandgap-independent photodetection mechanism. We report results for both bismuth telluride/antimony telluride and chromel/alumel structures as examples of a potentially broader class of resonant nanophotonic thermoelectric materials for optoelectronic applications such as non-bandgap-limited hyperspectral and broadband photodetectors