Enhanced protein adsorption due to charge regulation

When a protein molecule approaches a charged surface, its protonation state can undergo dramatic changes due to the imposed electric potential. This has a large impact on adsorption strengths that may be enhanced by several kT. Using mesoscopic simulation techniques as well as analytical theories, we have investigated this regulation mechanism and demonstrate how it is influenced by salt concentration and solution pH. Using hisactophilin as a test case, we show how the binding to a lipid membrane is governed by small changes in pH and that this is intimately coupled to the charge regulation mechanism.     

The absorption spectrum of localized electrons in crystalline 1,8-octanediol, γ-irradiated at 4.2 K

Crystalline 1.8-octanediol has been γ-irradiated and its optical absorption spectrum has been measured at 4.2 K. The spectrum consists of three partially resolved peaks with maxima at 740, 590, and 490 nm. The peaks cannot be separated by photobleaching or annealing. It is suggested that they arise from transitions inherent in each localized electron.     

Comment on “On the Anomalon Interpretation of 40Ar + Cu Collisions at 0.9 and 1.8 AGeV”

A recent article interpreted the experiment by Dersch et al. on the formation of ²⁴Na in ⁴⁰Ar + Cu interactions in a very simple manner. The results from emulsion experiments performed with 3.6 AGeV ²²Ne were adapted for the interpretation of the experiments with 1.8 AGeV ⁴⁰Ar. The model used the same mean value for the energy of minimum ionizing protons and pions at all angles. It is argued that a more complex approach is needed for a satisfactory interpretation.     

Effects of City-Size Heterogeneity on Epidemic Spreading in a Metapopulation: A Reaction-Diffusion Approach

We review and introduce a generalized reaction-diffusion approach to epidemic spreading in a metapopulation modeled as a complex network. The metapopulation consists of susceptible and infected individuals that are grouped in subpopulations symbolizing cities and villages that are coupled by human travel in a transportation network. By analytic methods and numerical simulations we calculate the fraction of infected people in the metapopulation in the long time limit, as well as the relevant parameters characterizing the epidemic threshold that separates an epidemic from a non-epidemic phase. Within this model, we investigate the effect of a heterogeneous network topology and a heterogeneous subpopulation size distribution. Such a system is suited for epidemic modeling where small villages and big cities exist simultaneously in the metapopulation. We find that the heterogeneous conditions cause the epidemic threshold to be a non-trivial function of the reaction rates (local parameters), the network’s topology (global parameters) and the cross-over population size that separates “village dynamics” from “city dynamics”.     

Fault-tolerant linear optical quantum computing with small-amplitude coherent States

Quantum computing using two coherent states as a qubit basis is a proposed alternative architecture with lower overheads but has been questioned as a practical way of performing quantum computing due to the fragility of diagonal states with large coherent amplitudes. We show that using error correction only small amplitudes (alpha>1.2) are required for fault-tolerant quantum computing. We study fault tolerance under the effects of small amplitudes and loss using a Monte Carlo simulation. The first encoding level resources are orders of magnitude lower than the best single photon scheme.     

Search for beta-delayed proton emission from $$^{11}$$Be

The European Physical Journal A - A deterministic treatment of sequential neutron emission, based on recursive equations of the residual temperatures, was applied to numerous fission cases (i.e. 49...     

Generation of Turbulent Inflow Data for Spatially-Developing Boundary Layer Simulations

A method for generating three-dimensional, time-dependent turbulent inflow data for simulations of complex spatially developing boundary layers is described. The approach is to extract instantaneous planes of velocity data from an auxiliary simulation of a zero pressure gradient boundary layer. The auxiliary simulation is also spatially developing, but generates its own inflow conditions through a sequence of operations where the velocity field at a downstream station is rescaled and re-introduced at the inlet. This procedure is essentially a variant of the Spalart method, optimized so that an existing inflow–outflow code can be converted to an inflow-generation device through the addition of one simple subroutine. The proposed method is shown to produce a realistic turbulent boundary layer which yields statistics that are in good agreement with both experimental data and results from direct simulations. The method is used to provide inflow conditions for a large eddy simulation (LES) of a spatially evolving boundary layer spanning a momentum thickness Reynolds number interval of 1530–2150. The results from the LES calculation are compared with those from other simulations that make use of more approximate inflow conditions. When compared with the approximate inflow generation techniques, the proposed method is shown to be highly accurate, with little or no adjustment of the solution near the inlet boundary. In contrast, the other methods surveyed produce a transient near the inlet that persists several boundary layer thicknesses downstream. Lack of a transient when using the proposed method is significant since the adverse effects of inflow errors are typically minimized through a costly upstream elongation of the mesh. Extension of the method for non-zero pressure gradients is also discussed.