73,790 research outputs found
Detection of confinement and jumps in single molecule membrane trajectories
We propose a novel variant of the algorithm by Simson et al. [R. Simson, E.D.
Sheets, K. Jacobson, Biophys. J. 69, 989 (1995)]. Their algorithm was developed
to detect transient confinement zones in experimental single particle tracking
trajectories of diffusing membrane proteins or lipids. We show that our
algorithm is able to detect confinement in a wider class of confining potential
shapes than Simson et al.'s one. Furthermore it enables to detect not only
temporary confinement but also jumps between confinement zones. Jumps are
predicted by membrane skeleton fence and picket models. In the case of
experimental trajectories of -opioid receptors, which belong to the family
of G-protein-coupled receptors involved in a signal transduction pathway, this
algorithm confirms that confinement cannot be explained solely by rigid fences.Comment: 4 pages, 3 figure
Short Introduction of Contract Law in Vietnam
Contract law is a vital aspect of all jurisdictions. It covers all everyday activities of the social-economic society of all countries, including developed and developing ones. Developed countries, based on strong economic foundations, still perfect the contract law to meet the needs of new situations. For developing countries, if they want to integrate into the International economy, they must continuously improve their laws, and contract law is one of the most important norms. Vietnam, a developing country undergoing the integration, must follow the general regulation which is perfecting its contract law. This short article focuses on the brief history and introduces basic contents of Vietnamese contract la
The Hyperfine Molecular Hubbard Hamiltonian
An ultracold gas of heteronuclear alkali dimer molecules with hyperfine
structure loaded into a one-dimensional optical lattice is investigated. The
\emph{Hyperfine Molecular Hubbard Hamiltonian} (HMHH), an effective low-energy
lattice Hamiltonian, is derived from first principles. The large permanent
electric dipole moment of these molecules gives rise to long range
dipole-dipole forces in a DC electric field and allows for transitions between
rotational states in an AC microwave field. Additionally, a strong magnetic
field can be used to control the hyperfine degrees of freedom independently of
the rotational degrees of freedom. By tuning the angle between the DC electric
and magnetic fields and the strength of the AC field it is possible to control
the number of internal states involved in the dynamics as well as the degree of
correlation between the spatial and internal degrees of freedom. The HMHH's
unique features have direct experimental consequences such as quantum
dephasing, tunable complexity, and the dependence of the phase diagram on the
molecular state
Sum rules in the heavy quark limit of QCD
In the leading order of the heavy quark expansion, we propose a method within
the OPE and the trace formalism, that allows to obtain, in a systematic way,
Bjorken-like sum rules for the derivatives of the elastic Isgur-Wise function
in terms of corresponding Isgur-Wise functions of transitions to
excited states. A key element is the consideration of the non-forward
amplitude, as introduced by Uraltsev. A simplifying feature of our method is to
consider currents aligned along the initial and final four-velocities. As an
illustration, we give a very simple derivation of Bjorken and Uraltsev sum
rules. On the other hand, we obtain a new class of sum rules that involve the
products of IW functions at zero recoil and IW functions at any . Special
care is given to the needed derivation of the projector on the polarization
tensors of particles of arbitrary integer spin. The new sum rules give further
information on the slope and also on the curvature
, and imply, modulo a very natural assumption, the
inequality , and therefore the absolute bound
.Comment: 64 pages, Late
Self-similar impulsive capillary waves on a ligament
We study the short-time dynamics of a liquid ligament, held between two solid
cylinders, when one is impulsively accelerated along its axis. A set of
one-dimensional equations in the slender-slope approximation is used to
describe the dynamics, including surface tension and viscous effects. An exact
self-similar solution to the linearized equations is successfully compared to
experiments made with millimetric ligaments. Another non-linear self-similar
solution of the full set of equations is found numerically. Both the linear and
non-linear solutions show that the axial depth at which the liquid is affected
by the motion of the cylinder scales like . The non-linear solution
presents the peculiar feature that there exists a maximum driving velocity
above which the solution disappears, a phenomenon probably related to
the de-pinning of the contact line observed in experiments for large pulling
velocities
Experimental investigation of fuel-cooled combustor: Cooling efficiency and coke formation
Scramjet is an air-breathing engine designed to propel advanced aircrafts in the atmosphere, suitable, according to various studies, to thrust high-speed hypersonic flights (over Mach 5). The thermal protection of vehicles flying at hypersonic velocities is a critical problem; as at supersonic speeds the incoming air is at too high temperature to be used as a coolant, the fuel becomes the only adequate source of cooling for the vehicle. Regenerative cooling is a well-known cooling technique using the fuel as coolant. As the development of regeneratively cooled engines faces many difficulties, an empirical study of this cooling technology and of its complex dynamics is of high interest. In this context, a remotely controlled fuel-cooled combustor, suitable for the experimental analysis of the pyrolysis-combustion coupling characterizing a fuel-cooled combustion chamber when a hydrocarbon propellant is used, has been designed. Tests are realized under both stationary and transient conditions using ethylene as fuel and air as oxidizer. Two operating parameters, i.e. fuel mass flow rate (between 0.010 and 0.040 g.s-1) and equivalence ratio (between 1.0 and 1.5), have been investigated. It has been observed that fuel mass flow rate increases always result in the raise of the heat flux density passing from the combustion gases to the combustor walls. It has been seen that mass flow rate raises between 16 and 20 % lead to increases in the thermal energy evacuated by the fuel-coolant in the range from 30.4 to 48.5 %, depending on equivalence ratio and pressure. The dependence of the cooling system heat exchange efficiency on the two operating parameters has been demonstrated. The consequences of the coking activity of the fuel have also been investigated. For applied interest, a monitoring method for carbon deposits formation has been developed and validated
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