7,300 research outputs found
Zero tension Kardar-Parisi-Zhang equation in (d+1)- Dimensions
The joint probability distribution function (PDF) of the height and its
gradients is derived for a zero tension -dimensional Kardar-Parisi-Zhang
(KPZ) equation. It is proved that the height`s PDF of zero tension KPZ equation
shows lack of positivity after a finite time . The properties of zero
tension KPZ equation and its differences with the case that it possess an
infinitesimal surface tension is discussed. Also potential relation between the
time scale and the singularity time scale of the KPZ
equation with an infinitesimal surface tension is investigated.Comment: 18 pages, 8 figure
Pomeranchuk effect and spin-gradient cooling of Bose-Bose mixtures in an optical lattice
We theoretically investigate finite-temperature thermodynamics and
demagnetization cooling of two-component Bose-Bose mixtures in a cubic optical
lattice, by using bosonic dynamical mean field theory (BDMFT). We calculate the
finite-temperature phase diagram, and remarkably find that the system can be
heated from the superfluid into the Mott insulator at low temperature,
analogous to the Pomeranchuk effect in 3He. This provides a promising many-body
cooling technique. We examine the entropy distribution in the trapped system
and discuss its dependence on temperature and an applied magnetic field
gradient. Our numerical simulations quantitatively validate the spin-gradient
demagnetization cooling scheme proposed in recent experiments.Comment: 9 pages, 8 figure
The dynamics of liquid slugs forced by a syringe pump
Microfluidic processes for chemical synthesis have become popular in recent years. The small scale of the chemical reactions promise greater control over reaction conditions and more timely creation of products. The small scale of microfluidics poses its own set of problems, however. At the microscale, the dominant fluid forces are viscous resistance and surface tension. The effects of viscosity and scale reduce the Reynolds number and make mixing difficult. Much work has been done to control mixing at the microscale.
This problem is concerned with a different microfluidic problem: delivering reactants to the site of reaction. A common setup is to attach syringes full of reactant to a reaction chamber by narrow hydrophobic tubing. Using a stepper motor, a controlled dose of liquid may be injected into the tube. The hydrophobosity causes the dose to curve outward on the sides, becoming a "slug" of reactant with air in front and behind. The syringe at the rear is then switched for one full of air, and air pressure is used to drive the slug to the reaction site.
If too much pressure is applied, the slug will arrive with a significant back pressure that will be relieved through bubbling in the reaction site. This causes the formation of a foam and is highly undesirable. We present a simple model based on Boyle’s law for the motion of a slug through a tube. We then extend this model for trains of slugs separated by air bubbles. Last, we consider the case of a flooded reaction site, where the forward air bubble must be pushed through the flooding liquid.
In conclusion, we have determined the dynamics of a single slug moving towards an empty reaction chamber giving the final equilibrium position of the slug. A phase-plane analysis then determined a condition on the size of the slug needed to ensure that it comes to rest without oscillating about the equilibrium position. The effect of a flooded reaction chamber was then considered. In this case it is impossible to avoid bubbling due to the design of the device. We found that it is possible, however, to reduce the bubbling by minimising the back pressure behind the slug. Finally, the dynamics of multiple slugs with or without a flooded reaction chamber has been investigated
An examination of iranian penal policies to deal with administrative and economic corruptions, emphasizing the islamic penal code that's been adopted in 2013
Economic crime imposes very costs to society and because of its complexity detection and prosecution in difficult. So required some prehensive criminal policy. This research try to survey Iran's criminal policy about economic crimes with emphasis on new penal code, enacted in 2013. The results indicate that legislator has not been defined "economic crimes" term but is considered its instances according to articles 47, 36,109 of new penal code. Fighting against Economic Crimes must be including preventive measures and criminal reaction. Preventive measures has been coherent by dictating of United Nations Convention against Corruption (UNCAC) and fighting against Corruption internal code (2011) but Iran's legislator has not taken coherent policy to fighting economic crimes by criminal reaction . Although the new penal Code adopted some strict against this crimes but we couldn’t see a coherent policy against its;Keywords: criminal policy, economic crimes, economic corruption, Islamic Penal Codethat's been adopted in 2013
Ultrahigh Purcell factors and Lamb shifts using slow-light metamaterial waveguides
Employing a medium-dependent quantum optics formalism and a Green function
solution of Maxwell's equations, we study the enhanced spontaneous emission
factors (Purcell factors) and Lamb shifts from a quantum dot or atom near the
surface of a %embedded in a slow-light metamaterial waveguide. Purcell factors
of approximately 250 and 100 are found at optical frequencies for polarized
and polarized dipoles respectively placed 28\thinspace nm (0.02\thinspace
) above the slab surface, including a realistic metamaterial loss
factor of . For smaller loss values, we
demonstrate that the slow-light regime of odd metamaterial waveguide
propagation modes can be observed and related to distinct resonances in the
Purcell factors. Correspondingly, we predict unusually large and rich Lamb
shifts of approximately -1 GHz to -6 GHz for a dipole moment of 50 Debye. We
also make a direct calculation of the far field emission spectrum, which
contains direct measurable access to these enhanced Purcell factors and Lamb
shifts
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