531 research outputs found
Dynamical symmetries and crossovers in a three-spin system with collective dissipation
We consider the non-equilibrium dynamics of a simple system consisting of
interacting spin- particles subjected to a collective damping. The model
is close to situations that can be engineered in hybrid electro/opto-mechanical
settings. Making use of large-deviation theory, we find a Gallavotti-Cohen
symmetry in the dynamics of the system as well as evidence for the coexistence
of two dynamical phases with different activity levels. We show that additional
damping processes smoothen out this behavior. Our analytical results are backed
up by Monte Carlo simulations that reveal the nature of the trajectories
contributing to the different dynamical phases.Comment: 6 pages, 5 figure
High resolution modelling of aerosol dispersion regimes during the CAPITOUL field experiment: from regional to local scale interactions
High resolution simulation of complex aerosol particle evolution and gaseous chemistry over an atmospheric urban area is of great interest for understanding air quality and processes. In this context, the CAPITOUL (Canopy and Aerosol Particle Interactions in the Toulouse Urban Layer) field experiment aims at a better understanding of the interactions between the urban dynamics and the aerosol plumes. During a two-day Intensive Observational Period, a numerical model experiment was set up to reproduce the spatial distribution of specific particle pollutants, from the regional scales and the interactions between different cities, to the local scales with specific turbulent structures. Observations show that local dynamics depends on the day-regime, and may lead to different mesoscale dynamical structures. This study focuses on reproducing these fine scale dynamical structures, and investigate the impact on the aerosol plume dispersion. The 500-m resolution simulation manages to reproduce convective rolls at local scale, which concentrate most of the aerosol particles and can locally affect the pollutant dispersion and air quality
Dose effect activity of ferrocifen-loaded lipid nanocapsules on a 9L-glioma model
Ferrociphenol (Fc-diOH) is a new molecule belonging to the fast-growing family of organometallic anti-cancer drugs. In a previous study, we showed promising in vivo results obtained after the intratumoural subcutaneous administration of the new drug-carrier system Fc-diOH-LNCs on a 9L-glioma model. To further increase the dose of this lipophilic entity, we have created a series of prodrugs of Fc-diOH. The phenol groups were protected by either an acetyl (Fc-diAc) or by the long fatty-acid chain of a palmitate (Fc-diPal). LNCs loaded with Fc-diOH prodrugs have to be activated in situ by enzymatic hydrolysis. We show here that the protection of diphenol groups with palmitoyl results in the loss of Fc-diOH in vitro activity, probably due to a lack of in situ hydrolysis. On the contrary, protection with an acetate group does not affect the strong, in vitro, antiproliferative effect of ferrocifen-loaded-LNCs neither the reduction of tumour volume observed on an ectopic model, confirming that acetate is easily cleaved by cell hydrolases. Moreover, the cytostatic activity of Fc-diOH-LNCs is confirmed on an orthotopic glioma model since the difference in survival time between the infusion of 0.36 mg/rat Fc-diOH-LNCs and blank LNCs is statistically significant. By using LNCs or Labrafac to carry the drug, a dose-effect ranging from 0.005 to 2.5mg of Fc-diOH per animal can be evidenced
High Performance Ultrasonic Inspection of Tubes
Eddy current examination was selected as the industrial method to be used for the inspection of PWR steam generator tubes because of both physical and operational advantages
Programmable and arbitrary-trajectory ultrafast flying focus pulses
"Flying focus" techniques produce laser pulses with dynamic focal points that
travels distances much greater than a Rayleigh length. The implementation of
these techniques in laser-based applications requires the design of optical
configurations that can both extend the focal range and structure the radial
group delay. This article describes a method for designing optical
configurations that produce ultrashort flying focus pulses with
arbitrary-trajectory focal points. The method is illustrated by several
examples that employ an axiparabola for extending the focal range and either a
reflective echelon or a deformable mirror-spatial light modulator pair for
structuring the radial group delay. The latter configuration enables rapid
exploration and optimization of flying foci, which could be ideal for
experiments
Spatiotemporal control of two-color terahertz generation
A laser pulse composed of a fundamental and properly phased second harmonic
exhibits an asymmetric electric field that can drive a time-dependent current
of photoionized electrons. The current produces an ultrashort burst of
terahertz (THz) radiation. When driven by a conventional laser pulse, the THz
radiation is emitted into a cone with an angle determined by the dispersion of
the medium. Here we demonstrate that the programmable-velocity intensity peak
of a spatiotemporally structured, two-color laser pulse can be used to control
the emission angle, focal spot, and spectrum of the THz radiation. Of
particular interest for applications, a structured pulse with a subluminal
intensity peak can drive highly focusable, on-axis THz radiation
Re-municipalization of public services: trend or hype?
Re-municipalization is part of a broader set of reverse privatization reforms. We argue the term re-municipalization lacks conceptual clarity and often confuses municipal level reversals from national ones, new service delivery from reversals, and mixed market positions (such as corporatization) from full public control. This conceptual confusion makes measurement of re-municipalization difficult. While more case studies are being discovered, studies based on quantitative time series do not show re-municipalization as an increasing trend. Much case study based research argues re-municipalization is politically transformative, but quantitative research generally finds re-municipalization to be part of a pragmatic market management process, a position confirmed by the papers in this special issue
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