Inequalities generalizing the second law of thermodynamics for transitions between non-stationary states

We discuss the consequences of a variant of the Hatano-Sasa relation in which a non-stationary distribution is used in place of the usual stationary one. We first show that this non-stationary distribution is related to a difference of traffic between the direct and dual dynamics. With this formalism, we extend the definition of the adiabatic and non-adiabatic entropies introduced by M. Esposito and C. Van den Broeck in Phys. Rev. Lett. 104, 090601 (2010) for the stationary case. We also obtain interesting second-law like inequalities for transitions between non-stationary states.Comment: 4 pages, 2 figure

Spin torque driven dynamics of a coupled two layer structure: interplay between conservative and dissipative coupling

In this manuscript the general concepts of spin wave theory are adapted to the dynamics of a self-polarized system based on two layers coupled via interlayer exchange (conservative coupling) and mutual spin torque (dissipative coupling). An analytical description of the non-linear dynamics is proposed and validated through numerical simulations. In contrast to the single layer model, the phase equation of the coupled system has a contribution coming from the dissipative part of the LLGS equation. It is shown that this is a major contribution to the frequency mandatory to describe well the most basic features of the dynamics of coupled systems. Using the proposed model a specific feature of coupled dynamics is addressed: the redshift to blueshift transition observed in the frequency current dependence of this kind of exchange coupled systems upon increasing the applied field. It is found that the blueshift regime can only occur in a region of field where the two linear eigenmodes contribute equally to the steady state mode (i.e. high mode hybridization). Finally, a general perturbed Hamiltonian equation for the coupled system is proposed.Comment: 16 pages, 7 figue

Transport Mean Free Path for Magneto-Transverse Light Diffusion

We derive an expression for the transport mean free path $\ell^*_\perp$ associated with magneto-transverse light diffusion for a random collection of Faraday-active Mie scatterers. This expression relates the magneto-transverse diffusion in multiple scattering directly to the magneto-transverse scattering of a single scatterer.Comment: 5 pages, 1 figure, Latex, accepted for publication in Europhysics Letter

Etude d'un réacteur aérobie à culture concentrée couplé à une séparation par micro ou ultra-filtration tangentielles sur membranes minérales. Première approche d'une application en dépollution

La réduction de la pollution organique des eaux usées, urbaines ou industrielles, fait le plus souvent appel à des procédés biologiques anaérobies ou aérobies. Dans ce dernier cas, les procédés à boues activées sont parmi les plus courants mais nécessitent de grands volumes de bassinsLes bioréacteurs à membranes présentent l'avantage de la compacité et permettent l'obtention d'un effluent de très bonne qualité, constante, même à très forte charge.Le système étudié ici est un bioréacteur faisant corps avec le module de filtration utilisé, avec injection d'oxygène dans la boucle, supprimant ainsi tout bassin conventionnel. Une eau usée synthétique y est traitée en aérobiose sur membranes minérales à une température de 30 °C, soit par ultrafiltration à 500 Å, soit par microfiltration à 0,2 µm. Le problème de l'encrassement des membranes est étudié et certains de ses mécanismes en présence d'une biomasse concentrée sont mis en évidence. L'encrassement est évitable en utilisant un décolmatage à flux inverse et en pratiquant des purges de boues régulières. La qualité de l'effluent obtenu en sortie est en tout point comparable ou supérieure à celle d'une station à boues activées travaillant en aération prolongée. La comparaison n'inclut pas les aspects économiques, et la nitrification est incomplète.Urban or industrial waste water organic pollution is must often treated by aerobic biological systems. In this case, commonly used activated sludge plants need large tanks. Membrane bioreactors would give compactness and very high and constant quality effluent. Up to now, organic membranes have been mainly utilized for polishing effluents from conventional secondary treatment. MEMCOR process, using hollow fibers membranes, allows permeate fluxes of 100 l/h.m2 for several months under a 1 bar pressure. Chaize (1990), using inorganic membranes for urban waste water treatment, reached high organic and nitrogen removal. Biomass was about 10 to 20 g/l and permeate fluxes of 20 and 28 l/h.m2 at 1.1 and 1.4 bar transmembrane pressure with residuals less than 20 ppm COD and SSM and 5 ppm TKN.Materials and methods :The pilot studied here combined in the same module a compact bioreactor and a filtration membrane. A synthetic waste water has been treated by crossflow micro or ultrafiltration with aerobic microorganisms and pure oxygen injection. This effluent had a DCOIDBO ratio of 1.5 with very low suspended solid matters (38 mg/l). a-Alumina (pore size : 0.2 µm) or Zirconium oxide (pore size : 500 Å) inorganic membranes have been used. As membrane fouling is the main weakness of this processes, two treatments have been experimented with both membranes :1. total biomass recycling without back flush system ;2. excess biomass draining with back-flush system operating.Experiments lasted continuously for 3 to 7 days.Crossflow velocity was about 3.8 m/s, pH was regulated at 7.0 by concentrated sodium hydroxide addition.Heat generated by pumps needed heat exchange with tap water in order to maintain temperature around 30 °C, wich was considered optimal for biological reactions.Permeate COD and nitrogen, biomass Suspended Volatile Matters (SVM) and Suspended Solid Matters (SSM) have been monitored.Results and discussion :1) Effluent quality was constant and better than for conventional extended aeration. The two membranes retained the whole of SSM and bacteria, permeate COD was less than 30 mg/l, even under high load conditions (5 to 20 kg COD/kg SVM.d), elimination rates reached 98 % BOD and 97 % COD. Biomass production and oxygen consumption were lower than for high load activated sludge process, tact reported to pure oxygen utilization and unfloculated bacteria predominance. Nitrification remained very low due to short sludge age (< 90 h).2) Membranes cleaning state at the beginning of the tests didn't modify stabilized permeate fluxes. Particulate fouling predominated with 0,2 µm membrane, problem solved using back-flush system, but fast slime fouling developed in the first 24 h. Electron microscopy membrane surface examination shown heavy fouling by a biofilm which real composition remains unknown, and by numerous small particles (site range from 0.04 to 0.3 mm).With total biomass recycling, permeate fluxes were very low for both types of membranes : 15 l/h.m2 for 500 Å membrane and 2 l/h.m2 for 0.2 µm membrane. Treatment had to be stopped alter only 99 h. Biomass concentration increased up to 32 g/l in 3 days. When using back flush system and regularly draining excess biomass, becter stabilized permeate fluxes could be observed : 35 l/h.m2 for 500 Å membrane and 24 l/h.m2 for 0.2 µm membrane. Mean biomass concentration was about 15 g/l.Enzymatic digestion of slimes on fouled membranes pointed out the role of bacteria colt walls and proteins. These compounds were thought to be produced mainly under substrate limitation conditions. Fouling could thus be avoided by regularly draining excess biomass.Technology of inorganic membranes is still recent and involves relatively high costs. However, as it may ha interesting for soma industrial effluents, tests are carried on to confirm chose results

Fluctuations of a driven membrane in an electrolyte

We develop a model for a driven cell- or artificial membrane in an electrolyte. The system is kept far from equilibrium by the application of a DC electric field or by concentration gradients, which causes ions to flow through specific ion-conducting units (representing pumps, channels or natural pores). We consider the case of planar geometry and Debye-H\"{u}ckel regime, and obtain the membrane equation of motion within Stokes hydrodynamics. At steady state, the applied field causes an accumulation of charges close to the membrane, which, similarly to the equilibrium case, can be described with renormalized membrane tension and bending modulus. However, as opposed to the equilibrium situation, we find new terms in the membrane equation of motion, which arise specifically in the out-of-equilibrium case. We show that these terms lead in certain conditions to instabilities.Comment: 7 pages, 2 figures. submitted to Europhys. Let

Coherent Backscattering of light in a magnetic field

This paper describes how coherent backscattering is altered by an external magnetic field. In the theory presented, magneto-optical effects occur inside Mie scatterers embedded in a non-magnetic medium. Unlike previous theories based on point-like scatterers, the decrease of coherent backscattering is obtained in leading order of the magnetic field using rigorous Mie theory. This decrease is strongly enhanced in the proximity of resonances, which cause the path length of the wave inside a scatterer to be increased. Also presented is a novel analysis of the shape of the backscattering cone in a magnetic field.Comment: 27 pages, 5 figures, Revtex, to appear in Phys. Rev.

Modified Fluctuation-dissipation theorem for non-equilibrium steady-states and applications to molecular motors

We present a theoretical framework to understand a modified fluctuation-dissipation theorem valid for systems close to non-equilibrium steady-states and obeying markovian dynamics. We discuss the interpretation of this result in terms of trajectory entropy excess. The framework is illustrated on a simple pedagogical example of a molecular motor. We also derive in this context generalized Green-Kubo relations similar to the ones derived recently by Seifert., Phys. Rev. Lett., 104, 138101 (2010) for more general networks of biomolecular states.Comment: 6 pages, 2 figures, submitted in EP

Lidar measurements and Umkehr observations of the ozone vertical distribution at the Observatoire de Haute Provence

This paper compares results of lidar and Umkehr measurements, made during 1985-1991, which include 110 coincidences. The Umkehr ozone profiles were retrieved using the conventional Umkehr method (Gotz et al., 1934; Mateer and Dutsch, 1964), the short Umkehr method (De Luisi, 1979), and the recently developed new-conventional Umkehr method (Mateer and De Luisi, 1992) in which the conventional method is referred to as the '1964 algorithm' and the new-conventional method as the '1991 algorithm'. Results obtained show good agreement between the ozone profiles derived using the new-conventional Umkehr method and lidar ozone profiles, emphasizing the influence of the temperature dependence of the ozone cross-sections on the Umkehr ozone retrievals

Local Optimal Sets and Bounded Archiving on Multi-objective NK-Landscapes with Correlated Objectives

The properties of local optimal solutions in multi-objective combinatorial optimization problems are crucial for the effectiveness of local search algorithms, particularly when these algorithms are based on Pareto dominance. Such local search algorithms typically return a set of mutually nondominated Pareto local optimal (PLO) solutions, that is, a PLO-set. This paper investigates two aspects of PLO-sets by means of experiments with Pareto local search (PLS). First, we examine the impact of several problem characteristics on the properties of PLO-sets for multi-objective NK-landscapes with correlated objectives. In particular, we report that either increasing the number of objectives or decreasing the correlation between objectives leads to an exponential increment on the size of PLO-sets, whereas the variable correlation has only a minor effect. Second, we study the running time and the quality reached when using bounding archiving methods to limit the size of the archive handled by PLS, and thus, the maximum size of the PLO-set found. We argue that there is a clear relationship between the running time of PLS and the difficulty of a problem instance.Comment: appears in Parallel Problem Solving from Nature - PPSN XIII, Ljubljana : Slovenia (2014

An On-Farm experimental philosophy for farmer-centric digital innovation

In this paper, we review learnings gained from early On-Farm Experiments (OFE) conducted in the broad acre Australian grain industry from the 1990s to the present day. Although the initiative was originally centered around the possibilities of new data and analytics in precision agriculture, we discovered that OFEs could represent a platform for engaging farmers around digital technologies and innovation. Insight from interacting closely with farmers and advisors leads us to argue for a change in the ways we approach OFE research. Acknowledging that conditions have changed and drawing from business and social sciences, we suggest that OFE approaches today should develop aspects related to skill development, value generation and value sharing, the social dimension of change, and a renewed focus on farmer-centric research to better bridge industry requirements and scientist inputs