Continuous Observation of Interference Fringes from Bose Condensates

We use continuous measurement theory to describe the evolution of two Bose condensates in an interference experiment. It is shown how the system evolves in a single run of the experiment into a state with a fixed relative phase, while the total gauge symmetry remains unbroken. Thus, an interference pattern is exhibited without violating atom number conservation.Comment: 4 pages, Postscrip

Time evolution of deformation in a human cartilage under cyclic loading

Recent imaging has revealed that in vivo contact deformations of human knee cartilage under physiological loadings are surprisingly large—typically on the order of 10%, but up to 20 or 30% of tibiofemora cartilage thickness depending on loading conditions. In this paper we develop a biphasic, large deformation, non-linear poroelastic model of cartilage that can accurately represent the time dependence and magnitude of cyclic cartilage deformations in vivo. The model takes into account cartilage tension–compression nonlinearity and a new constitutive relation in which the compressive stiffness and hydraulic permeability of the cartilage adjusts in response to the strain-dependent aggrecan concentration. The model predictions are validated using experimental test results on osteochondral plugs obtained from human cadavers. We find that model parameters can be optimised to give an excellent fit to the experimental data. Using typical hydraulic conductivity and stiffness parameters for healthy cartilage, we find that the experimentally observed transient and steady state tissue deformations under cyclic loading and unloading can be reproduced by the model. Steady state tissue deformations are shown to cycle between 10% (exudation strain) and 20% (total strain) in response to the cyclic test loads. At steady-state cyclic loading, the pore fluid exuded from the tissue is exactly equal to the pore fluid imbibed by the tissue during each load cycle

Singular solutions of the diffusion equation of population genetics

The forward diffusion equation for gene frequency dynamics is solved subject to the condition that the total probability is conserved at all times. This can lead to solutions developing singular spikes (Dirac delta functions) at the gene frequencies 0 and 1. When such spikes appear in solutions they signal gene loss or gene fixation, with the "weight" associated with the spikes corresponding to the probability of loss or fixation. The forward diffusion equation is thus solved for all gene frequencies, namely the absorbing frequencies of 0 and 1 along with the continuous range of gene frequencies on the interval (0; 1) that excludes the frequencies 0 and 1. Previously, the probabilities if the absorbing frequencies 0 and 1 were found by appeal to the backward diffusion equation, while those in the continuous range (0; 1) were found from the forward diffusion equation. Our uni fied approach does not require two separate equations for a complete dynamical treatment of all gene frequencies within a diffusion approximation framework. For cases involving mutation, migration and selection, it is shown that a property of the deterministic part of gene frequency dynamics determines when fixation and loss can occur. It is also shown how solution of the forward equation, at long times, leads to the standard result for the fixation probability

Reframing global palliative care advocacy for the sustainable development goal era: A qualitative study of the views of international palliative care experts

Context The World Health Assembly Palliative Care Resolution in 2014 and the inclusion of palliative care within the sustainable development goals raised optimism that palliative care would no longer be a peripheral aspect of global health. However, no funding, accountability measures, or indicators for palliative care development accompanied these policy developments. This risks health actors continuing to prioritize the attainment of better known target-driven aspects of health care. Objectives To explore the attitudes of international palliative care experts regarding how the future development of palliative care can be accelerated. Methods About 16 international palliative care experts were interviewed for their epistemic expertise. Participants were interviewed face to face or via Skype. Interviews were recorded, transcribed nonverbatim, and analyzed using a thematic approach (NVivo). Results Participants strongly supported the rollout of national palliative care policies around the world for two reasons: to ensure palliative care attracts national funding streams and to attract global funding for palliative care. The absence of a global indicator for palliative care development was considered a severe impediment to the inclusion of palliative care within global efforts toward universal health care. Advocacy partnerships, using human rights approaches with economic frames, were considered the most effective methods of influencing policymakers. Conclusion Palliative care represents a value proposition that is not currently being maximized by advocacy. Advocates should consider palliative care developmentally, focusing on key asks for development and consider how palliative care can contribute to other international development priorities, in particular poverty reduction

Quantum Kinetic Theory III: Quantum kinetic master equation for strongly condensed trapped systems

We extend quantum kinetic theory to deal with a strongly Bose-condensed atomic vapor in a trap. The method assumes that the majority of the vapor is not condensed, and acts as a bath of heat and atoms for the condensate. The condensate is described by the particle number conserving Bogoliubov method developed by one of the authors. We derive equations which describe the fluctuations of particle number and phase, and the growth of the Bose-Einstein condensate. The equilibrium state of the condensate is a mixture of states with different numbers of particles and quasiparticles. It is not a quantum superposition of states with different numbers of particles---nevertheless, the stationary state exhibits the property of off-diagonal long range order, to the extent that this concept makes sense in a tightly trapped condensate.Comment: 3 figures submitted to Physical Review

Nitrofurantoin and fosfomycin for resistant urinary tract infections: old drugs for emerging problems

Uncomplicated urinary tract infection is one of the most common indications for antibiotic use in the community. However, the Gram-negative organisms that can cause the infection are becoming more resistant to antibiotics. Many multidrug resistant organisms retain susceptibility to two old antibiotics, nitrofurantoin and fosfomycin. Advantages over newer drugs include their high urinary concentrations and minimal toxicity. Fosfomycin is a potential treatment option for patients with uncomplicated urinary tract infection due to resistant organisms. Nitrofu

Nonlinearity effects in the kicked oscillator

The quantum kicked oscillator is known to display a remarkable richness of dynamical behaviour, from ballistic spreading to dynamical localization. Here we investigate the effects of a Gross Pitaevskii nonlinearity on quantum motion, and provide evidence that the qualitative features depend strongly on the parameters of the system.Comment: 4 pages, 5 figure

The Bogoliubov Theory of a BEC in Particle Representation

In the number-conserving Bogoliubov theory of BEC the Bogoliubov transformation between quasiparticles and particles is nonlinear. We invert this nonlinear transformation and give general expression for eigenstates of the Bogoliubov Hamiltonian in particle representation. The particle representation unveils structure of a condensate multiparticle wavefunction. We give several examples to illustrate the general formalism.Comment: 10 pages, 9 figures, version accepted for publication in Phys. Rev.

Predicting knee osteoarthritis

Treatment options for osteoarthritis (OA) beyond pain relief or total knee replacement are very limited. Because of this, attention has shifted to identifying which factors increase the risk of OA in vulnerable populations in order to be able to give recommendations to delay disease onset or to slow disease progression. The gold standard is then to use principles of risk management, first to provide subject-specific estimates of risk and then to find ways of reducing that risk. Population studies of OA risk based on statistical associations do not provide such individually tailored information. Here we argue that mechanistic models of cartilage tissue maintenance and damage coupled to statistical models incorporating model uncertainty, united within the framework of structural reliability analysis, provide an avenue for bridging the disciplines of epidemiology, cell biology, genetics and biomechanics. Such models promise subject-specific OA risk assessment and personalized strategies for mitigating or even avoiding OA. We illustrate the proposed approach with a simple model of cartilage extracellular matrix synthesis and loss regulated by daily physical activity