Adding memory to pressure-sensitive phosphors

Mechanoluminescence (ML) is the phenomenon describing the emission of light during mechanical action on a solid, leading to applications such as pressure sensing, damage detection and visualization of stress distributions. In most cases, this mechanical action releases energy that was previously stored in the crystal lattice of the phosphor by means of trapped charge carriers. A drawback is the need to record the ML emission during a pressure event. In this work, we provide a method for adding a memory function to these pressure-sensitive phosphors, allowing an optical readout of the location and intensity of a pressure event in excess of 72 h after the event. This is achieved in the BaSi2O2N2:Eu2+ phosphor, where a broad trap depth distribution essential for the process is present. By merging optically stimulated luminescence (OSL), thermoluminescence (TL) and ML measurements, the influence of light, heat and pressure on the trap depth distribution is carefully analysed. This analysis demonstrates that mechanical action can not only lead to direct light emission but also to a reshuffling of trap occupations. This memory effect not only is expected to lead to new pressure sensing applications but also offers an approach to study charge carrier transitions in energy storage phosphors

A contribution of experimental economics toward characterization of the use of market power in oligopolisitc markets

Despite the numerous researches about imperfect competition, the market power remains difficult to quantify using traditional economics methods. In this paper, we propose an experimental economics design and outline some ways of analysis of its results toward characterization of the use of market power. A simple system with two regions and a limited interconnection transfer capacity allocated by an implicit auction is studied. Depending on the experiments two or three subjects share equitably the production capacity in one region, while the production capacity is equitably shared among 5 subjects leading to a more competitive situation in the second one. In both regions, we observe a market price that is different from the theoretical results allowing a quantification of the use of market power. Results are also analyzed based on a characterization of the subjects' behaviour. Further the impact of subjects' behaviour on the market price evolution is described.experimental economics, market power, electricity markets, oligopolistic markets

Making Pictures

(What follows is adapted from a talk that Ted Estess, former Dean of the University of Houston Honors College, delivered at the college’s Convocation on August 29, 2013.) During the last week of my last semester in my last year in college, I took a course in aesthetics. David Miller was the teacher, and he required all of the students to make a presentation. I decided to work up a presentation on Picasso. I didn’t know much about Picasso, but of course that did not deter me. A word of advice to students: never let the fact that you do not altogether know what you are talking about keep you from talking. After all, not knowing what they are talking about does not stop your parents from talking, does it? And how do you think professors could possibly lecture for an entire semester without occasionally talking about things that they don’t know much about? Certainly they do not know all there is to know about all the things that they talk about

Micro-tectonic constraints on the evolution of the Barles half-window (Digne Nappe, southern Alps). Implications for the timing of folding in the Valensole foreland basin

International audienceThe "Vélodrome" overturned syncline, at the northern margin of the Cenozoic foreland basin of Valensole in SE France, was formed during the Late Cenozoic at the front of the Digne nappe. Microstructural analyses reveal that mesoscale faulting in the molassic series, from the Oligocene "Molasse Rouge" at the base to the middle to late Miocene "Valensole Conglomerates" at the top, partly occurred before the folding, as layer-parallel shortening: the NNE-SSW-directed compression is recorded by two systems of reverse and strike-slip faults, which formed when the strata were still horizontal and were passively tilted as folding occurred. These data suggest that the Vélodrome folding postdates the deposition of the Valensole Conglomerates and occurred in late Miocene-Pliocene times during the emplacement of the Digne nappe. These results are difficult to reconcile with the interpretation of the Vélodrome as a growth fold progressively formed in 10-15 m.y. during the deposition of the Miocene molasses. Structural data collected in the Barles tectonic half-window enable to reconstruct the evolution of the deformation since the Jurassic. The two main phases of shortening, the pre-Oligocene Pyrenean-Provençal and the Mio-Pliocene Alpine phases, are almost homoaxial with a direction of compression trending N-S for the former and NNE-SSW for the later. A late Eocene-basal Oligocene N-S extensional episode is documented between these two phases, probably in relation with the formation of the western European rift system. The direction of extension of the Liassic rifting of the Alpine Tethys is roughly constrained in the NW-SE quadrant. Paleo-stress field reconstruction brings consistent results at the regional scale and proves to be a powerful tool to decipher the evolution of the deformation in a remarkably complicated tectonic setting

Dextran sulfate enhances the level of an oxidative DNA damage biomarker, 8-oxo-7,8-dihydro-2 0-deoxyguanosine, in rat colonic mucosa

Dextran sodium sulfate (DSS) given in drinking water can induce colonic Inflammation and produce colorectal tumors in rodents, although it is not directly genotoxic. The hypothesis that DSS can produce free radicals and induce oxidative DNA damage in colonic mucosa has been tested. In rats fed for 2 days with water containing 3% and 6% DSS, colonic Inflammation manifestations were recorded and 8-oxo-7,8-dihydro-2 0-deoxyguanosine (8-oxodGuo), a major biomarker of oxidative DNA damage, was assayed in colonic mucosa. As compared with control rats given pure water, inflammatory manifestations were seen in rats given DSS. At the same time, 8-oxodGuo levels in colonic mucosa were doubled (P , 0:001). These results suggest that formation of oxidative DNA damage in colonic mucosa depends on inflammation and maybe on the production of reactive oxygen species. This study shows that DSS can induce oxidative DNA damage within only 2 days, which could explain in part its carcinogenic properties

Commande par platitude. Equations différentielles ordinaires et aux dérivées partielles

DEACommande par platitude. Equations différentielles ordinaires et aux dérivées partielle