434 research outputs found
Hamiltonian traffic dynamics in microfluidic-loop networks
Recent microfluidic experiments revealed that large particles advected in a
fluidic loop display long-range hydrodynamic interactions. However, the
consequences of such couplings on the traffic dynamics in more complex networks
remain poorly understood. In this letter, we focus on the transport of a finite
number of particles in one-dimensional loop networks. By combining numerical,
theoretical, and experimental efforts, we evidence that this collective process
offers a unique example of Hamiltonian dynamics for hydrodynamically
interacting particles. In addition, we show that the asymptotic trajectories
are necessarily reciprocal despite the microscopic traffic rules explicitly
break the time reversal symmetry. We exploit these two remarkable properties to
account for the salient features of the effective three-particle interaction
induced by the exploration of fluidic loops
Estimation of the electron beam-induced specimen heating and the emitted X-rays spatial resolution by Kossel microdiffraction in a scanning electron microscope
Lien vers la version éditeur: http://www.sciencedirect.com/science/article/pii/S0304399112000307A Kossel microdiffraction experimental setup has been developed inside a Scanning Electron Micro-scope for crystallographic orientation, strain and stress determination at a micrometer scale. This paper reports an estimation of copper and germanium specimens heating due to the electron beam bombardment. The temperature rise is calculated from precise lattice parameters measurement considering different currents induced in the specimens. The spatial resolution of the technique is then deduced
Emergent hyperuniformity in periodically-driven emulsions
We report the emergence of large-scale hyperuniformity in microfluidic
emulsions. Upon periodic driving confined emulsions undergo a first-order
transition from a reversible to an irreversible dynamics. We evidence that this
dynamical transition is accompanied by structural changes at all scales
yielding macroscopic yet finite hyperuniform structures. Numerical simulations
are performed to single out the very ingredients responsible for the
suppression of density fluctuations. We show that as opposed to equilibrium
systems the long-range nature of the hydrodynamic interactions are not required
for the formation of hyperuniform patterns, thereby suggesting a robust
relation between reversibility and hyperuniformity which should hold in a broad
class of periodically driven materials.Comment: 5p, 3f, submitte
Tunable source of correlated atom beams
We use a one-dimensional optical lattice to modify the dispersion relation of
atomic matter waves. Four-wave mixing in this situation produces atom pairs in
two well defined beams. We show that these beams present a narrow momentum
correlation, that their momenta are precisely tunable, and that this pair
source can be operated both in the regime of low mode occupancy and of high
mode occupancy
Estimation of the electron beam-induced specimen heating and the emitted X-rays spatial resolution by Kossel microdiffraction in a scanning electron microscope
Lien vers la version éditeur: http://www.sciencedirect.com/science/article/pii/S0304399112000307A Kossel microdiffraction experimental setup has been developed inside a Scanning Electron Micro-scope for crystallographic orientation, strain and stress determination at a micrometer scale. This paper reports an estimation of copper and germanium specimens heating due to the electron beam bombardment. The temperature rise is calculated from precise lattice parameters measurement considering different currents induced in the specimens. The spatial resolution of the technique is then deduced
Stress analysis by Kossel microdiffraction on a nickel-based single crystal superalloy during an in situ tensile test – Comparison with classical X-Ray diffraction
A Kossel microdiffraction experimental set up is under development inside a Scanning Electron Microscope (SEM) in order to determine the crystallographic orientation as well as the inter- and intragranular strains and stresses. An area of about one cubic micrometer can be analysed using the microscope probe, which enables to study different kinds of elements such as a grain boundary, a crack, a microelectronic component, etc. The diffraction pattern is recorded by a high resolution Charge-Coupled Device (CCD) camera. The crystallographic orientation, the lattice parameters and the elastic strain tensor of the probed area are deduced from the pattern indexation using a homemade software. The purpose of this paper is to report some results achieved up to now to estimate the reliability of the Kossel microdiffraction technique
An acoustic analog to the dynamical Casimir effect in a Bose-Einstein condensate
We have realized an acoustic analog to the Dynamical Casimir effect. The
density of a trapped Bose-Einstein condensate is modulated by changing the trap
stiffness. We observe the creation of correlated excitations with equal and
opposite momenta, and show that for a well defined modulation frequency, the
frequency of the excitations is half that of the trap modulation frequency.Comment: Includes supplemental informatio
Cholesterol metabolism in apolipoprotein E4 mice
Carrying at least one apolipoprotein E ε4 allele (E4+) is the main genetic risk factor for Alzheimer's disease (AD). Epidemiological studies support that consuming fatty fish rich in docosahexaenoic acid (DHA; 22:6ω3) is protective against development of AD. However, this protective effect seems not to hold in E4+. The involvement of APOE genotype on the relationship between DHA intake and cognitive decline could be mediated through cholesterol. Many studies show a link between cholesterol metabolism and AD progression. In this study, we investigated whether cholesterol metabolism is improved in E3+ and E4+ mice consuming a diet rich in DHA. Plasma cholesterol was 36% lower in E4+ mice compared to E3+ mice fed the control diet (P=.02), and in the liver, there was a significant genotype effect where cholesterol levels were 18% lower in E4+ mice than E3+ mice. The low-density lipoprotein receptor was overexpressed in the liver of E4+ mice. Plasma cholesterol levels were 33% lower after the DHA diet (P=.02) in E3+ mice only, and there was a significant diet effect where cholesterol level was 67% lower in the liver of mice fed DHA. Mice fed the DHA diet also had 62% less lipolysis stimulated lipoprotein receptor expression in the liver compared to mice fed the control diet (P<.0001), but there was no genotype effect. These findings suggest that plasma and liver cholesterol homeostasis and the receptors regulating uptake of cholesterol in the liver are modulated differently and independently by APOE allele and DHA intake
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