9,699 research outputs found
All-optical transport and compression of ytterbium atoms into the surface of a solid immersion lens
We present an all-optical method to load 174Yb atoms into a single layer of
an optical trap near the surface of a solid immersion lens which improves the
numerical aperture of a microscope system. Atoms are transported to a region 20
um below the surface using a system comprised by three optical dipole traps.
The "optical accordion" technique is used to create a condensate and compress
the atoms to a width of 120 nm and a distance of 1.8 um away from the surface.
Moreover, we are able to verify that after compression the condensate behaves
as a two-dimensional quantum gas.Comment: 5 pages, 5 figure
Two-Dimensional Fluctuating Vesicles in Linear Shear Flow
The stochastic motion of a two-dimensional vesicle in linear shear flow is
studied at finite temperature. In the limit of small deformations from a
circle, Langevin-type equations of motion are derived, which are highly
nonlinear due to the constraint of constant perimeter length. These equations
are solved in the low temperature limit and using a mean field approach, in
which the length constraint is satisfied only on average. The constraint
imposes non-trivial correlations between the lowest deformation modes at low
temperature. We also simulate a vesicle in a hydrodynamic solvent by using the
multi-particle collision dynamics technique, both in the quasi-circular regime
and for larger deformations, and compare the stationary deformation correlation
functions and the time autocorrelation functions with theoretical predictions.
Good agreement between theory and simulations is obtained.Comment: 13 pages, 7 figure
Feasibility of Application of Modern Methods of Construction in Iran
Various plans and policies have been adopted by the Iranian Government to address the housing shortages in Iran. Some of these policies have been successful and some have failed dramatically deteriorating the housing conditions. Technology transfer from other countries, such as the UK, may facilitate industrialisation which has been recognised as an effective way to address housing deficiencies in Iran. The Iranian and UK construction industries, however, differ in various respects which may increase the risk of failure if transferred technologies are not adapted to Iranian needs and conditions. This paper compares the current conditions of the Iranian and UK construction industries to identify the risks and opportunities if Modern Methods of Construction (MMC) were to be transferred from the UK to Iran. Several issues such as demand and supply, regulations and standards, practicality, costs, design, sustainability, and governmental policies have been studied in detail. The results reveal that MMC could potentially improve the housing conditions in Iran by addressing major issues such as skilled labour shortages, energy and materials wastes, building quality and speed of construction. The major risks are also identified as volatile economy and housing market, transportation and industry capacity. The chance of successful adoption is considerably higher for those MMC that are suitable for small projects, do not require highly skilled labour and heavy machinery, and are compatible with prevailing methods of construction in Iran
Solvent-free coarse-grained lipid model for large-scale simulations
A coarse-grained molecular model, which consists of a spherical particle and
an orientation vector, is proposed to simulate lipid membrane on a large length
scale. The solvent is implicitly represented by an effective attractive
interaction between particles. A bilayer structure is formed by
orientation-dependent (tilt and bending) potentials. In this model, the
membrane properties (bending rigidity, line tension of membrane edge, area
compression modulus, lateral diffusion coefficient, and flip-flop rate) can be
varied over broad ranges. The stability of the bilayer membrane is investigated
via droplet-vesicle transition. The rupture of the bilayer and worm-like
micelle formation can be induced by an increase in the spontaneous curvature of
the monolayer membrane.Comment: 13 pages, 19 figure
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