Microscopic Study of 1S0{}^1{S_0} Superfluidity in Dilute Neutron Matter

Singlet $S$-wave superfluidity of dilute neutron matter is studied within the correlated BCS method, which takes into account both pairing and short-range correlations. First, the equation of state (EOS) of normal neutron matter is calculated within the Correlated Basis Function (CBF) method in lowest cluster order using the ${}^1{S_0}$ and ${}^3P$ components of the Argonne $V_{18}$ potential, assuming trial Jastrow-type correlation functions. The ${}^1{S_0}$ superfluid gap is then calculated with the corresponding component of the Argonne $V_{18}$ potential and the optimally determined correlation functions. The dependence of our results on the chosen forms for the correlation functions is studied, and the role of the $P$-wave channel is investigated. Where comparison is meaningful, the values obtained for the ${}^1{S_0}$ gap within this simplified scheme are consistent with the results of similar and more elaborate microscopic methods.Comment: 9 pages, 6 figure

Time-dependent transport through a T-coupled quantum dot

We are considering the time-dependent transport through a discrete system, consiting of a quantum dot T-coupled to an infinite tight-binding chain. The periodic driving that is induced on the coupling between the dot and the chain, leads to the emergence of a characteristic multiple Fano resonant profile in the transmission spectrum. We focus on investigating the underlying physical mechanisms that give rise to the quantum resonances. To this end, we use Floquet theory for calculating the transmission spectrum and in addition employ the Geometric Phase Propagator (GPP) approach [Ann. Phys. 375, 351 (2016)] to calculate the transition amplitudes of the time-resolved virtual processes, in terms of which we describe the resonant behavior. This two fold approach, allows us to give a rigorous definition of a quantum resonance in the context of driven systems and explains the emergence of the characteristic Fano profile in the transmission spectrum.Comment: 9 pages, 4 figure

Computational study of the interaction between a newtonian fluid and a cellular biological medium in a straight vessel

In this work, we solve numerically the governing equations for quasi-steady Newtonian flow past and through a cellular biological medium, which is attached to the surface of a straight vessel. The flow past the cellular biological medium is described by the Navier-Stokes equations. For the modeling of momentum transfer within the cellular biological medium, we consider that the cellular biological medium constitutes a biphasic fluid-solid mixture with poroelastic behaviour. The system of governing equations is solved numerically with the mixed finite element method. The computational domain is discretized using an unstructured, variable density triangular element mesh. From the numerical solution we obtain the spatial distributions of: (i) the fluid velocity and pressure, and (ii) the displacement and stresses of the solid matrix within the cellular biological medium. Also, the components of the overall hydrodynamic force exerted by the flowing fluid on the cellular biological medium are calculated. A parametric analysis is performed with regard to the Reynolds and Darcy numbers that characterize the flow past and through the cellular biological medium

Hierarchical hybrid simulation of biofilm growth dynamics in 3D porous media

Recently, we developed the first hierarchical, hybrid simulator for the prediction of the pattern of evolution and the rate of growth of heterogeneous biofilms within the pore space of porous media [Kapellos et al., Adv. Water Resour. (2007) 30:1648-1667]. A n improved version of our simulator is presented in this work. A continuum-based approach for fluid flow and solute transport is combined with individual-based approaches for biofilm growth, detachment, and migration in the pore space. The Navier-Stokes-Brinkman equations are solved numerically with a marker-and-cell finite difference scheme to determine the velocity and pressure fields in the pore space. Momentum transport in the biofilms is described in the context of biphasic poroelasticity and a Galerkin finite element method is used to determine the solid stress field. Shear-induced biofilm detachment is taken into account explicitly and a Lagrangian-type simulation is used to determine the trajectories of detached fragments. Nutrient transport in the pore space is described by the convectiondiffusion- reaction equation, which is solved numerically with an operator-splitting finite difference scheme. Further, a novel, physically-constrained cellular-automaton model is used for biofilm proliferation. As an example application, the simulator is used to investigate the impact of biofilm formation on the fate and transport of suspended particles in a network of three-dimensional pores

Paradoxical and powerful: Volunteers’ experiences of befriending people with dementia

This qualitative UK study explored the lived experiences of volunteer befrienders to people with dementia, using interpretative phenomenological analysis. Individual semi-structured interviews were conducted with nine befrienders aged between 25 and 66 years. The relationship that developed between befriender and befriendee was at the heart of befrienders’ experiences. It comprised numerous paradoxical processes that generated issues of power, equality and boundaries, characterising befriending as a complex and unique phenomenon. Befriending was expressed as a deeply personal and human experience, often with emotional power and profound meaning. Befrienders’ personal learning included seeing past dementia stereotypes, challenging their own assumptions and boundaries, and reflecting on love, life and humanness. Dissemination of these findings could help to challenge the stigma around dementia, and enhance recruitment and support of dementia befrienders. Future research should consider befriendee experiences of the relationship, additional measures of befriending effectiveness, and exploration of befriender attrition and support. </jats:p

Olfactory dysfunction is common in classical infratentorial superficial siderosis of the central nervous system

BACKGROUND: Established features of classical infratentorial superficial siderosis (iSS) include hearing loss, impaired balance, myelopathy and, less commonly, cognitive compromise. Olfactory function may be affected but dedicated studies are lacking. This study aimed to assess the prevalence of olfactory dysfunction in iSS and correlate it with auditory and cognitive functions. METHODS: Ten participants with iSS completed the University of Pennsylvania Smell Identification Test (UPSIT). The scores were compared with population norms; regression analysis was performed to evaluate associations between the scores and hearing thresholds (3-frequency average, 3FA) or the number of cognitive domains impaired. Imaging was reviewed for haemosiderin distribution and to exclude other causes of olfactory and hearing dysfunction. RESULTS: Eight of ten participants were male; the mean (standard deviation, SD) age was 52.5 (14.5) years. Olfactory hypofunction was identified in all participants and in six (60%) was moderate or completely absent. The mean UPSIT score of 25.5 (7.8) was significantly worse than population norms (difference in means - 10.0; 95% CI - 15.6 to - 4.4). Linear regression identified an association between UPSIT and hearing thresholds (R = 0.75; p = 0.013). The score decreases by 0.157 units (95% CI - 0.31 to - 0.002; p = 0.048) per unit increase in 3FA, after adjusting for hearing loss risk factors. There was no statistically significant association between UPSIT and cognitive function (R = 0.383; p = 0.397). CONCLUSION: We report a high prevalence of olfactory dysfunction in iSS, the severity of which correlated with hearing loss. Olfaction appears to be a core feature of the iSS clinical syndrome that should be assessed routinely