4,438 research outputs found
A general correlation inequality and the Almost Sure Local Limit Theorem for random sequences in the domain of attraction of a stable law
In the present paper we obtain a new correlation inequality and use it for
the purpose of extending the theory of the Almost Sure Local Limit Theorem to
the case of lattice random sequences in the domain of attraction of a stable
law. In particular, we prove ASLLT in the case of the normal domain of
attraction of --stable law,
Anderson localization of pairs in bichromatic optical lattices
We investigate the formation of bound states made of two interacting atoms
moving in a one dimensional (1D) quasi-periodic optical lattice. We derive the
quantum phase diagram for Anderson localization of both attractively and
repulsively bound pairs. We calculate the pair binding energy and show
analytically that its behavior as a function of the interaction strength
depends crucially on the nature -extended, multi-fractal, localized- of the
single-particle atomic states. Experimental implications of our results are
discussed.Comment: final revised version with more explanations, 4 pages, 3 figure
Food waste materials appear efficient and low-cost adsorbents for the removal of organic and inorganic pollutants from wastewater
In recent studies, the adsorption capacity of several food waste materials has been assessed by performing adsorption experiments in heterogeneous operating conditions. In a latest study, the efficiency of such food waste materials for the removal of metals and metalloids from complex multi-element
solutions was evaluated in homogeneous experimental conditions, which allowed comparing the adsorption capacities of the individual adsorbents. Considering the high efficiency of the examined low-cost adsorbents for the removal of inorganic pollutants, preliminary studies were conducted in our lab for assessing the potential of the investigated food waste materials to adsorb volatile organic compounds from a real polluted matrix of leachate. Some recent
studies have shown the efficiency of low cost materials for the removal of industrial organic dyes, polycyclic aromatic hydrocarbons and phenolic compounds. However, the food waste adsorbents’ efficiency for the removal of volatile organic compounds was not investigated. Our preliminary studies showed good adsorption capacities of the examined food waste materials for aliphatic and aromatic hydrocarbons. Therefore, it is worth to carry out further studies about volatile organic compounds’ removal by food waste adsorbents
The observed chemical structure of L1544
Prior to star formation, pre-stellar cores accumulate matter towards the
centre. As a consequence, their central density increases while the temperature
decreases. Understanding the evolution of the chemistry and physics in this
early phase is crucial to study the processes governing the formation of a
star. We aim at studying the chemical differentiation of a prototypical
pre-stellar core, L1544, by detailed molecular maps. In contrast with single
pointing observations, we performed a deep study on the dependencies of
chemistry on physical and external conditions. We present the emission maps of
39 different molecular transitions belonging to 22 different molecules in the
central 6.25 arcmin of L1544. We classified our sample in five families,
depending on the location of their emission peaks within the core. Furthermore,
to systematically study the correlations among different molecules, we have
performed the principal component analysis (PCA) on the integrated emission
maps. The PCA allows us to reduce the amount of variables in our dataset.
Finally, we compare the maps of the first three principal components with the
H column density map, and the T map of the core. The results of
our qualitative analysis is the classification of the molecules in our dataset
in the following groups: (i) the -CH family (carbon chain
molecules), (ii) the dust peak family (nitrogen-bearing species), (iii) the
methanol peak family (oxygen-bearing molecules), (iv) the HNCO peak family
(HNCO, propyne and its deuterated isotopologues). Only HCO and
CS do not belong to any of the above mentioned groups. The principal
component maps allow us to confirm the (anti-)correlations among different
families that were described in a first qualitative analysis, but also points
out the correlation that could not be inferred before.Comment: 29 pages, 19 figures, 2 appendices, accepted for publication in A&A,
arXiv abstract has been slightly modifie
Thermodynamic Bounds on Efficiency for Systems with Broken Time-reversal Symmetry
We show that for systems with broken time-reversal symmetry the maximum
efficiency and the efficiency at maximum power are both determined by two
parameters: a "figure of merit" and an asymmetry parameter. In contrast to the
time-symmetric case, the figure of merit is bounded from above; nevertheless
the Carnot efficiency can be reached at lower and lower values of the figure of
merit and far from the so-called strong coupling condition as the asymmetry
parameter increases. Moreover, the Curzon-Ahlborn limit for efficiency at
maximum power can be overcome within linear response. Finally, always within
linear response, it is allowed to have simultaneously Carnot efficiency and
non-zero power.Comment: Final version, 4 pages, 3 figure
Frustration of decoherence in -shaped superconducting Josephson networks
We examine the possibility that pertinent impurities in a condensed matter
system may help in designing quantum devices with enhanced coherent behaviors.
For this purpose, we analyze a field theory model describing Y- shaped
superconducting Josephson networks. We show that a new finite coupling stable
infrared fixed point emerges in its phase diagram; we then explicitly evidence
that, when engineered to operate near by this new fixed point, Y-shaped
networks support two-level quantum systems, for which the entanglement with the
environment is frustrated. We briefly address the potential relevance of this
result for engineering finite-size superconducting devices with enhanced
quantum coherence. Our approach uses boundary conformal field theory since it
naturally allows for a field-theoretical treatment of the phase slips
(instantons), describing the quantum tunneling between degenerate levels.Comment: 11 pages, 5 .eps figures; several changes in the presentation and in
the figures, upgraded reference
- …