Spontaneous emission of a nanoscopic emitter in a strongly scattering disordered medium

Fluorescence lifetimes of nitrogen-vacancy color centers in individual diamond nanocrystals were measured at the interface between a glass substrate and a strongly scattering medium. Comparison of the results with values recorded from the same nanocrystals at the glass-air interface revealed fluctuations of fluorescence lifetimes in the scattering medium. After discussing a range of possible systematic effects, we attribute the observed lengthening of the lifetimes to the reduction of the local density of states. Our approach is very promising for exploring the strong three-dimensional localization of light directly on the microscopic scale.Comment: 9 pages, 4 figure

New Results for Diffusion in Lorentz Lattice Gas Cellular Automata

New calculations to over ten million time steps have revealed a more complex diffusive behavior than previously reported, of a point particle on a square and triangular lattice randomly occupied by mirror or rotator scatterers. For the square lattice fully occupied by mirrors where extended closed particle orbits occur, anomalous diffusion was still found. However, for a not fully occupied lattice the super diffusion, first noticed by Owczarek and Prellberg for a particular concentration, obtains for all concentrations. For the square lattice occupied by rotators and the triangular lattice occupied by mirrors or rotators, an absence of diffusion (trapping) was found for all concentrations, except on critical lines, where anomalous diffusion (extended closed orbits) occurs and hyperscaling holds for all closed orbits with {\em universal} exponents ${\displaystyle{d_f = \frac{7}{4}}}$ and ${\displaystyle{\tau = \frac{15}{7}}}$. Only one point on these critical lines can be related to a corresponding percolation problem. The questions arise therefore whether the other critical points can be mapped onto a new percolation-like problem, and of the dynamical significance of hyperscaling.Comment: 52 pages, including 18 figures on the last 22 pages, email: [email protected]

An Intersecting Loop Model as a Solvable Super Spin Chain

In this paper we investigate an integrable loop model and its connection with a supersymmetric spin chain. The Bethe Ansatz solution allows us to study some properties of the ground state. When the loop fugacity $q$ lies in the physical regime, we conjecture that the central charge is $c=q-1$ for $q$ integer $< 2$. Low-lying excitations are examined, supporting a superdiffusive behavior for $q=1$. We argue that these systems are interesting examples of integrable lattice models realizing $c \leq 0$ conformal field theories.Comment: latex file, 7 page

Thermodynamic formalism for systems with Markov dynamics

The thermodynamic formalism allows one to access the chaotic properties of equilibrium and out-of-equilibrium systems, by deriving those from a dynamical partition function. The definition that has been given for this partition function within the framework of discrete time Markov chains was not suitable for continuous time Markov dynamics. Here we propose another interpretation of the definition that allows us to apply the thermodynamic formalism to continuous time. We also generalize the formalism --a dynamical Gibbs ensemble construction-- to a whole family of observables and their associated large deviation functions. This allows us to make the connection between the thermodynamic formalism and the observable involved in the much-studied fluctuation theorem. We illustrate our approach on various physical systems: random walks, exclusion processes, an Ising model and the contact process. In the latter cases, we identify a signature of the occurrence of dynamical phase transitions. We show that this signature can already be unravelled using the simplest dynamical ensemble one could define, based on the number of configuration changes a system has undergone over an asymptotically large time window.Comment: 64 pages, LaTeX; version accepted for publication in Journal of Statistical Physic

Advanced turboprop multidisciplinary design and optimization within agile project

The present paper deals with the design, analysis and optimization of a 90 passengers turboprop aircraft with a design range of 1200 nautical miles and a cruise Mach number equal to 0.56. The prescribed aircraft is one of the use cases of the AGILE European project, aiming to provide a 3rd generation of multidisciplinary design and optimization chain, following the collaborative and remote aircraft design paradigm, through an heterogenous team of experts. The multidisciplinary aircraft design analysis is set-up involving tools provided by AGILE partners distributed worldwide and run locally from partners side. A complete design of experiment, focused on wing planform variables, is performed to build response surfaces suitable for optimization purposes. The goal of the optimization is the direct operating cost, subject to wing design variables and top-level aircraft requirements

Metastable states in glassy systems

Truly stable metastable states are an artifact of the mean-field approximation or the zero temperature limit. If such appealing concepts in glass theory as configurational entropy are to have a meaning beyond these approximations, one needs to cast them in a form involving states with finite lifetimes. Starting from elementary examples and using results of Gaveau and Schulman, we propose a simple expression for the configurational entropy and revisit the question of taking flat averages over metastable states. The construction is applicable to finite dimensional systems, and we explicitly show that for simple mean-field glass models it recovers, justifies and generalises the known results. The calculation emphasises the appearance of new dynamical order parameters.Comment: 4 fig., 20 pages, revtex; added references and minor change

Excited Charmed Mesons: Observations, Analyses and Puzzles

We review the status of recently observed positive parity charmed resonances, both in the non-strange and in the strange sector. We describe the experimental findings, the main theoretical analyses and the open problems deserving further investigations.Comment: LaTeX, 25 pages, 5 figures. Invited revie

Brownian fluctuations and heating of an optically aligned gold nanorod

Biological and Soft Matter Physic

(Not so) Great Expectations: Listening to Foreign-Accented Speech Reduces the Brain's Anticipatory Processes.

This study examines the effect of foreign-accented speech on the predictive ability of our brain. Listeners actively anticipate upcoming linguistic information in the speech signal so as to facilitate and reduce processing load. However, it is unclear whether or not listeners also do this when they are exposed to speech from non-native speakers. In the present study, we exposed native Dutch listeners to sentences produced by native and non-native speakers while measuring their brain activity using electroencephalography. We found that listeners' brain activity differed depending on whether they listened to native or non-native speech. However, participants' overall performance as measured by word recall rate was unaffected. We discussed the results in relation to previous findings as well as the automaticity of anticipation

Life is in the air: An expedition into the Amazonian atmosphere

Biological particles suspended in the atmosphere have a crucial role in the dynamics of the biosphere underneath. Although much attention is paid for the chemical and physical properties of these particles, their biological taxonomic identity, which is relevant for ecological research, remains little studied. We took air samples at 300 meters above the forest in central Amazonia, in seven periods of 7 days, and used high-throughput DNA sequencing techniques to taxonomically identify airborne fungal and plant material. The use of a molecular identification technique improved taxonomic resolution when compared to morphological identification. This first appraisal of airborne diversity showed that fungal composition was strikingly different from what has been recorded in anthropogenic regions. For instance, basidiospores reached 30% of the OTUs instead of 3–5% as found in the literature; and the orders Capnodiales and Eurotiales—to which many allergenic fungi and crop pathogens belong—were much less frequently recorded than Pleosporales, Polyporales, and Agaricales. Plant OTUs corresponded mainly to Amazonian taxa frequently present in pollen records such as the genera Helicostilys and Cecropia and/or very abundant in the region such as Pourouma and Pouteria. The origin of extra-Amazonian plant material is unknown, but they belong to genera of predominantly wind-pollinated angiosperm families such as Poaceae and Betulaceae. Finally, the detection of two bryophyte genera feeds the debate about the role of long distance dispersal in the distribution of these plants