L'effet CSI: état de l'art sur un phénomène aux multiples facettes

Depuis son lancement en 2000, la série policière "Les Experts" ("CSI : Crime Scene Investigations" en version originale) a été l'une des séries les plus populaires dans son genre tant aux Etats-Unis qu'ailleurs dans le monde. En raison de la représentation idéalisée la science forensique véhiculée au fil des épisodes, certains acteurs juridiques américains on exprimé, par l'intermédiaire de la presse populaire, l'inquiétude selon laquelle de telles séries puissent hausser les attentes des jurés vis-à-vis des indices matériels présentés au tribunal. Le terme "effet CSI" a ainsi été créé afin de désigner l'influence des séries de genre forensique, particulièrement "Les experts", sur la prise de décision des jurés lors des procès. Par la suite, l'utilisation de ce terme s'est étendue aux autres acteurs sociaux et juridiques. Cet article a pour but de présenter en détail l' "effet CSI" par le biais d'une recherche bibliographique des travaux effectués sur le sujet. La typologie des principaux effets décrits dans la littérature, l'évolution spatio-temporelle de l'emploi de ce terme, ainsi que les principaux points de vue et constats sont présentés. Cette compilation bibliographique révèle que les principaux champs de recherche de l' "effet CSI" peuvent changer en fonction de la zone géographique. D'une manière générale, il ressort que les séries policières peuvent être vecteurs d'informations propres à modifier la perception de la science forensique par le grand public mais qu'elles ne sont pas les seuls médias à produire une image réaliste de la criminalité et du système de justice pénale. Ces sources de divertissement peuvent quelquefois être éducatives mais peuvent également avoir pour effet de provoquer une hausse des attentes du citoyen ordinaire envers la police technique et l'indice matériel, sans pour autant constituer une menace pour le système de justice pénale

Effect of nitrogenous bases on the thermal stability of jet fuels

Fuels from naphthenic petroleums were evaluated, and it was found that they had more N bases than those paraffinic ones (0.00024 and 0.000009% N, respectively). The removal of the N bases improved significantly the thermal stability and reduced the residue formation during oxidation of the fuel. The improvement depended on both content and composition of the bases. Thus, fuels with similar content of N bases (0.00058% N) and thermal stability had oxidation residues of 17.5 and 5.6 and sol. gum of 13 and 1.5 mg/100 ml, before and after removing the N bases, respectively

Signature of a silver phase percolation threshold in microscopically phase separated ternary Ge0.15Se0.85-xAgx (0 <= x <= 0.20) glasses

Temperature modulated Alternating Differential Scanning Calorimetric (ADSC) studies show that Se rich Ge0.15Se0.85-xAgx (0 <= x <= 0.20) glasses are microscopically phase separated, containing Ag2Se phases embedded in a Ge0.15Se0.85 backbone. With increasing silver concentration, Ag2Se phase percolates in the Ge-Se matrix, with a well-defined percolation threshold at x = 0.10. A signature of this percolation transition is shown up in the thermal behavior, as the appearance of two exothermic crystallization peaks. Density, molar volume and micro-hardness measurements, undertaken in the present study, also strongly support this view of percolation transition. The super-ionic conduction observed earlier in these glasses at higher silver proportions, is likely to be connected with the silver phase percolation.Comment: 4 pages, 7 figure

Observational Diagnostics of Gas Flows: Insights from Cosmological Simulations

Galactic accretion interacts in complex ways with gaseous halos, including galactic winds. As a result, observational diagnostics typically probe a range of intertwined physical phenomena. Because of this complexity, cosmological hydrodynamic simulations have played a key role in developing observational diagnostics of galactic accretion. In this chapter, we review the status of different observational diagnostics of circumgalactic gas flows, in both absorption (galaxy pair and down-the-barrel observations in neutral hydrogen and metals; kinematic and azimuthal angle diagnostics; the cosmological column density distribution; and metallicity) and emission (Lya; UV metal lines; and diffuse X-rays). We conclude that there is no simple and robust way to identify galactic accretion in individual measurements. Rather, progress in testing galactic accretion models is likely to come from systematic, statistical comparisons of simulation predictions with observations. We discuss specific areas where progress is likely to be particularly fruitful over the next few years.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dave, to be published by Springer. Typos correcte

Diffuse-Charge Dynamics in Electrochemical Systems

The response of a model micro-electrochemical system to a time-dependent applied voltage is analyzed. The article begins with a fresh historical review including electrochemistry, colloidal science, and microfluidics. The model problem consists of a symmetric binary electrolyte between parallel-plate, blocking electrodes which suddenly apply a voltage. Compact Stern layers on the electrodes are also taken into account. The Nernst-Planck-Poisson equations are first linearized and solved by Laplace transforms for small voltages, and numerical solutions are obtained for large voltages. The ``weakly nonlinear'' limit of thin double layers is then analyzed by matched asymptotic expansions in the small parameter $\epsilon = \lambda_D/L$, where $\lambda_D$ is the screening length and $L$ the electrode separation. At leading order, the system initially behaves like an RC circuit with a response time of $\lambda_D L / D$ (not $\lambda_D^2/D$), where $D$ is the ionic diffusivity, but nonlinearity violates this common picture and introduce multiple time scales. The charging process slows down, and neutral-salt adsorption by the diffuse part of the double layer couples to bulk diffusion at the time scale, $L^2/D$. In the ``strongly nonlinear'' regime (controlled by a dimensionless parameter resembling the Dukhin number), this effect produces bulk concentration gradients, and, at very large voltages, transient space charge. The article concludes with an overview of more general situations involving surface conduction, multi-component electrolytes, and Faradaic processes.Comment: 10 figs, 26 pages (double-column), 141 reference

Gas Accretion and Giant Lyman-alpha Nebulae

Several decades of observations and discoveries have shown that high-redshift AGN and massive galaxies are often surrounded by giant Lyman-alpha nebulae extending in some cases up to 500 kpc in size. In this review, I discuss the properties of the such nebulae discovered at z>2 and their connection with gas flows in and around the galaxies and their halos. In particular, I show how current observations are used to constrain the physical properties and origin of the emitting gas in terms of the Lyman-alpha photon production processes and kinematical signatures. These studies suggest that recombination radiation is the most viable scenario to explain the observed Lyman-alpha luminosities and Surface Brightness for the large majority of the nebulae and imply that a significant amount of dense, ionized and cold clumps should be present within and around the halos of massive galaxies. Spectroscopic studies suggest that, among the giant Lyman-alpha nebulae, the one associated with radio-loud AGN should have kinematics dominated by strong, ionized outflows within at least the inner 30-50 kpc. Radio-quiet nebulae instead present more quiescent kinematics compatible with stationary situation and, in some cases, suggestive of rotating structures. However, definitive evidences for accretion onto galaxies of the gas associated with the giant Lyman-alpha emission are not unambiguously detected yet. Deep surveys currently ongoing using other bright, non-resonant lines such as Hydrogen H-alpha and HeII1640 will be crucial to search for clearer signatures of cosmological gas accretion onto galaxies and AGN.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dave', to be published by Springe

Gas Accretion and Star Formation Rates

Cosmological numerical simulations of galaxy evolution show that accretion of metal-poor gas from the cosmic web drives the star formation in galaxy disks. Unfortunately, the observational support for this theoretical prediction is still indirect, and modeling and analysis are required to identify hints as actual signs of star-formation feeding from metal-poor gas accretion. Thus, a meticulous interpretation of the observations is crucial, and this observational review begins with a simple theoretical description of the physical process and the key ingredients it involves, including the properties of the accreted gas and of the star-formation that it induces. A number of observations pointing out the connection between metal-poor gas accretion and star-formation are analyzed, specifically, the short gas consumption time-scale compared to the age of the stellar populations, the fundamental metallicity relationship, the relationship between disk morphology and gas metallicity, the existence of metallicity drops in starbursts of star-forming galaxies, the so-called G dwarf problem, the existence of a minimum metallicity for the star-forming gas in the local universe, the origin of the alpha-enhanced gas forming stars in the local universe, the metallicity of the quiescent BCDs, and the direct measurements of gas accretion onto galaxies. A final section discusses intrinsic difficulties to obtain direct observational evidence, and points out alternative observational pathways to further consolidate the current ideas.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springe

Modulation of Biofilm Growth by Sub‐Inhibitory Amounts of Antibacterial Substances

It is generally accepted that bacteria in biofilm are more resistant to antibacterials than their planktonic counterparts. For numerous antibiotics, it has been shown that minimal inhibitory concentrations (MICs) for bacteria grown in broth are much lower than the minimal biofilm inhibition concentrations. While sub‐inhibitory concentrations, that is, amounts of antibacterials below the MIC, do not either influence or suppress to some extent or other the bacterial growth in liquid media, these same amounts of drugs, natural substances, etc., may have diverse effects on bacterial biofilms, ranging from suppression to stimulation of the sessile growth and varying with regard to the bacterial species and strains. This is a source of additional risks for both biofilm infection of host tissues and contamination indwelling devices. When considering the data for biofilm modulation, differences in experimental protocols should be taken into account, as well as the strain‐specific mechanisms of biofilm formation

Influence of Fruit Juice From Aronia Melanocarpa on the Process of Lipid Peroxidation in a Model of Carbon Tetrachloride-Induced Hepatotoxicity in Rats

The fruit juice from Aronia melanocarpa (FJAM) is rich in anthocyanins. We studied the effect of FJAM on the process of lipid peroxidation in a model of carbon tetrachloride (CCI4)-induced hepatotoxicity in rats. Malondialdehyde (MDA) levels were measured in plasma and liver homogenate. CCU induced a significant elevation of MDA levels in the plasma (p<0,05) and in the homogenate (p<0,01) in comparison with distilled water-treated controls. FJAM applied alone did not significantly influence on the MDA levels. The pretreatment of the rats with FJAM before their treatment with CCI4 lead dose-dependently to MDA levels in the plasma and homogenate which did not differ in most animal groups from the controls and were significantly lower from those of the CCI4-treated rats