Colloid-oil-water-interface interactions in the presence of multiple salts: charge regulation and dynamics

We theoretically and experimentally investigate colloid-oil-water-interface interactions of charged, sterically stabilized, poly(methyl-methacrylate) colloidal particles dispersed in a low-polar oil (dielectric constant $\epsilon=5-10$) that is in contact with an adjacent water phase. In this model system, the colloidal particles cannot penetrate the oil-water interface due to repulsive van der Waals forces with the interface whereas the multiple salts that are dissolved in the oil are free to partition into the water phase. The sign and magnitude of the Donnan potential and/or the particle charge is affected by these salt concentrations such that the effective interaction potential can be highly tuned. Both the equilibrium effective colloid-interface interactions and the ion dynamics are explored within a Poisson-Nernst-Planck theory, and compared to experimental observations.Comment: 13+2 pages, 5+3 figures; V2: small clarifications in the tex

Stadsplanten en bijen

De belangstelling voor de natuur in de stad is sinds de jaren 90 van de vorige eeuw enorm toegenomen. Uit allerlei gegevens blijkt dat de biodiversiteit in de stad veel groter is dan men op het eerste gezicht zou verwachten. Voor het beleven van de natuur hoef je niet helemaal naar een natuurreservaat te gaan. In het jaar 2000 verscheen ‘Stadsecologie’ van Jelle Reumer en in 2004 ‘Stadsplanten’ van Ton Denters. Beide boeken inspireerden biologen van allerlei pluimage om eens goed rond te kijken in de stad

Constructive plaquette compilation for the parity architecture

Parity compilation is the challenge of laying out the required constraints for the parity mapping in a local way. We present the first constructive compilation algorithm for the parity architecture using plaquettes for arbitrary higher-order optimization problems. This enables adiabatic protocols, where the plaquette layout can natively be implemented, as well as fully parallelized digital circuits. The algorithm builds a rectangular layout of plaquettes, where in each layer of the rectangle at least one constraint is added. The core idea is that each constraint, consisting of any qubits on the boundary of the rectangle and some new qubits, can be decomposed into plaquettes with a deterministic procedure using ancillas. We show how to pick a valid set of constraints and how this decomposition works. We further give ways to optimize the ancilla count and show how to implement optimization problems with additional constraints.Comment: 8 pages, 5 figure

Optogenetics and Light-Sheet Microscopy

Light-sheet microscopy is a powerful method for imaging small translucent samples in vivo, owing to its unique combination of fast imaging speeds, large field of view, and low phototoxicity. This chapter briefly reviews state-of-the-art technology for variations of light-sheet microscopy. We review recent examples of optogenetics in combination with light-sheet microscopy and discuss some current bottlenecks and horizons of light sheet in all-optical physiology. We describe how 3-dimensional optogenetics can be added to an home-built light-sheet microscope, including technical notes about choices in microscope configuration to consider depending on the time and length scales of interest

Hofstadter butterflies of carbon nanotubes: Pseudofractality of the magnetoelectronic spectrum

The electronic spectrum of a two-dimensional square lattice in a perpendicular magnetic field has become known as the Hofstadter butterfly [Hofstadter, Phys. Rev. B 14, 2239 (1976).]. We have calculated quasi-one-dimensional analogs of the Hofstadter butterfly for carbon nanotubes (CNTs). For the case of single-wall CNTs, it is straightforward to implement magnetic fields parallel to the tube axis by means of zone folding in the graphene reciprocal lattice. We have also studied perpendicular magnetic fields which, in contrast to the parallel case, lead to a much richer, pseudofractal spectrum. Moreover, we have investigated magnetic fields piercing double-wall CNTs and found strong signatures of interwall interaction in the resulting Hofstadter butterfly spectrum, which can be understood with the help of a minimal model. Ubiquitous to all perpendicular magnetic field spectra is the presence of cusp catastrophes at specific values of energy and magnetic field. Resolving the density of states along the tube circumference allows recognition of the snake states already predicted for nonuniform magnetic fields in the two-dimensional electron gas. An analytic model of the magnetic spectrum of electrons on a cylindrical surface is used to explain some of the results.Comment: 14 pages, 12 figures update to published versio

Інформаційне суспільство як нова утопічна модель розвитку світу

У статті аналізується утопія як нова суперечлива інформаційно-технічна ідилія. Автор розглядає утопію інформаційного суспільства як орієнтацію на те, що відсутнє у суспільстві. Досліджується формування утопій ХХ ст., котрі, залежно він поставленої мети, впливають на особистість і творять нові цінності.The article examines utopia as a new contradictory information and technical idyll. The utopia of the information society is considered to be an orientation on what is missing in society. The author investigates the formation of utopias of the twentieth century, which affect personality and create new values depending on their persecuted goals