Global measurement of water waves by Fourier transform profilometry

In this paper, we present an optical profilometric technique that allows for single-shot global measurement of free-surface deformations. This system consists of a high-resolution system composed of a videoprojector and a digital camera. A fringe pattern of known characteristics is projected onto the free surface and its image is registered by the camera. The deformed fringe pattern arising from the surface deformations is later compared to the undeformed (reference) one, leading to a phase map from which the free surface can be reconstructed. Particularly, we are able to project wavelength-controlled sinusoidal fringe patterns, which considerably increase the overall performance of the technique and the quality of the reconstruction compared to that obtained with a Ronchi grating. In comparison to other profilometric techniques, it allows for single-shot non-intrusive measurement of surface deformations over large areas. In particular, our measurement system and analysis technique is able to measure free surface deformations with sharp slopes up to 10 with a 0.2 mm vertical resolution over an interrogation window of size 450 × 300 mm² sampled on approximately 6.1 × 10⁶ measurement points. Some illustrative examples of the application of this measuring system to fluid dynamics problems are presented.

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Pseudopower expansion of solutions of generalized equations and constrained optimization problems

We show that the solution of a strongly regular generalized equation subject to a scalar perturbation expands in pseudopower series in terms of the perturbation parameter, i.e., the expansion of orderk is the solution of generalized equations expanded to orderk and thus depends itself on the perturbation parameter. In the polyhedral case, this expansion reduces to a usual Taylor expansion. These results are applied to the problem of regular perturbation in constrained optimization. We show that, if the strong regularity condition is satisfied, the property of quadratic growth holds and, at least locally, the solutions of the optimization problem and of the associated optimality system coincide. If, in addition the number of inequality constraints is finite, the solution and the Lagrange multiplier can be expanded in Taylor series. If the data are analytic, the solution and the multiplier are analytic functions of the perturbation parameter.     

Proteome analysis of the culture environment supporting undifferentiated mouse embryonic stem and germ cell growth

The therapeutical interest of pluripotent cells and ethical issues related to the establishment of human embryonic stem cell (ESC) or embryonic germ cell (EGC) lines raise the understanding of the mechanism underlying pluripotency to a fundamental issue. Establishing a protein pluripotency signature for these cells can be complicated by the presence of unrelated proteins produced by the culture environment. Here, we have analyzed the environment supporting ESC and EGC growth, and established 2-D reference maps for each constituent present in this culture environment: mouse embryonic fibroblast feeder cells, culture medium (CM) and gelatin. The establishment of these reference maps is essential prior to the study of ESC and EGC specific proteomes. Indeed, these maps can be subtracted from ESC or EGC maps to allow focusing on spots specific for ESCs or EGCs. Our study led to the identification of 110 unique proteins from fibroblast feeder cells and 23 unique proteins from the CM, which represent major contaminants of ESC and EGC proteomes. For gelatin, no collagen-specific proteins were identified, most likely due to difficulties in resolution and low quantities. Furthermore, no differences were observed between naive and conditioned CM. Finally, we compared these reference maps to ESC 2-D gels and isolated 17 ESC specific spots. Among these spots, proteins that had already been identified in previous human and mouse ESC proteomes were identified but no apparent ESC-specific pluripotency marker could be identified. This work represents an essential step in furthering the knowledge of environmental factors supporting ESC and EGC growth.     

Complexity of a one-to-one meeting scheduling problem with two types of actors

This article deals with a new scheduling problem that arises in the organization of one-to-one meetings in parallel. We first introduce applications of one-to-one meeting scheduling problems. Then, we give an overview of the relevant complexity results. We then prove several complexity results for different versions of the problem.     

An eco-friendly route to magnetic silica microspheres and nanospheres

A green and inexpensive alternative to existing methods for the preparation of magnetic iron oxide/silica nanocomposite particles has been investigated. The use of water-in oil emulsions based on vegetable oils instead of usual solvents led to microsized or nanosized magnetic silica spheres exhibiting similar characteristics to those of classical procedures. Furthermore this approach is very general since a large class of porous magnetic colloids differing in size or iron oxide fraction has been obtained. This work emphasizes the importance of the level of the shearing during the emulsification step with regard to the size and monodispersity of the prepared beads. All the materials prepared were fully characterized (SEM and TEM microscopies, SQUID magnetometry, N(2) sorption volumetry, etc.). In addition, samples functionalized by thiol groups have been synthesized and successfully tested for the removal of heavy metals in water-treatment.     

Photoacoustic spectroscopy for trace gas detection with cryogenic and room-temperature continuous-wave quantum cascade lasers

The main characteristics that a sensor must possess for trace gas detection and pollution monitoring are high sensitivity, high selectivity and the capability to perform in situ measurements. The photacoustic Helmholtz sensor developed in Reims, used in conjunction with powerful Quantum Cascade Lasers (QCLs), fulfils all these requirements. The best cell response is # 1200 V W⁻¹ cm and the corresponding ultimate sensitivity is j 3.3 × 10⁻¹⁰ W cm⁻¹¹ Hz^−11/2. This efficient sensor is used with mid-infrared QCLs from Alpes Lasers to reach the strong fundamental absorption bands of some atmospheric gases. A first cryogenic QCL emitting at 7.9 μm demonstrates the detection of methane in air with a detection limit of 3 ppb. A detection limit of 20 ppb of NO in air is demonstrated using another cryogenic QCL emitting in the 5.4 μm region. Real in-situ measurements can be achieved only with room-temperature QCLs. A room-temperature QCL emitting in the 7.9 μm region demonstrates the simultaneous detection of methane and nitrous oxide in air (17 and 7 ppb detection limit, respectively). All these reliable measurements allow the estimated detection limit for various atmospheric gases using quantum cascade lasers to be obtained. Each gas absorbing in the infrared may be detected at a detection limit in the ppb or low-ppb range.