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

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

The nonrelativistic limit of the Magueijo-Smolin model of deformed special relativity

We study the nonrelativistic limit of the motion of a classical particle in a model of deformed special relativity and of the corresponding generalized Klein-Gordon and Dirac equations, and show that they reproduce nonrelativistic classical and quantum mechanics, respectively, although the rest mass of a particle no longer coincides with its inertial mass. This fact clarifies the meaning of the different definitions of velocity of a particle available in DSR literature. Moreover, the rest mass of particles and antiparticles differ, breaking the CPT invariance. This effect is close to observational limits and future experiments may give indications on its effective existence.Comment: 10 pages, plain TeX. Discussion of generalized Dirac equation and CPT violation adde

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

3D Bioprinting and Near-Field Electrospinning Composite Scaffolds for the Bone-Ligament Interface

3D bioprinting is an additive manufacturing technique that can utilize a range of bioactive materials to construct specific architectures that mimic native tissue. Near-field electrospinning (NFE) offers precise alignment control to create non-woven mats with high tensile strengths. We built a custom E-spin printer that enables layer-by-layer alternating deposition between 3D bioprinting and NFE to create composite scaffolds for the bone-ligament interface. This complex region is difficult to simulate due to its functionally graded mechanical and biochemical properties. We created NFE poly(caprolactone) highly aligned micro-fibers which formed collagen fibril-like bundles. Poly(ethylene glycol) diacrylate with decellularized bone was encased in the PCL fibers to create bony ligament support structures in a composite scaffold. Cytotoxicity of all materials was determined through a Live/Dead assay (Thermo Fisher) with NIH/3T3 cells. The materials and the composite scaffold were seeded with 3T3 cells and cultured for three days before undergoing an immunocytochemistry staining (ICC) to assess cell adhesion and spreading. Increased adhesion and spreading on decellularized bone scaffolds along with cell elongation in the direction of the fibers suggests the ability of the scaffold to encourage osteoblastic differentiation and ligamentous tissue formation, though a longitudinal study is still underway. Mechanical results suggest that the composite scaffolds have increased compressive strength over PEGDA alone as the PCL fibers constrict horizontal elongation, thus yielding a higher compressive modulus. The PCL fibers demonstrated a tensile strength approaching native ligament (3.96 ± 1.10 MPa), which shows promise as the ligament phase of the scaffold. The E-spin printer’s versatility with materials of disparate viscosities enabled the layer-by-layer fabrication of composite (PCL/PEGDA+bone) scaffolds that begin to mimic the complex nature of the bone-ligament interface