Theoretical study of a plasma accelerator

Two-dimensional unsteady flow established in an electrodeless traveling wave plasma accelerator was theoretically analyzed to help explain, and possibly predict, phenomena appearing during experiments on problems of acceleration of an ionized fluid plasma

Two-dimensional Unsteady Flow in a Traveling Wave Plasma Accelerator

Two-dimensional unsteady flow in traveling wave plasma accelerator studied using small perturbation theor

Sub-Alfvenic flow in a duct with a nonuniform magnetic field

Flow of conducting fluid in duct with nonuniform magnetic fiel

Developing a novel hepatitis B core – based antigen presentation system

Plant-produced proteins of pharmaceutical interest are beginning to reach the market, and the advantages of transient plant expression systems are gaining increasing recognition. In parallel, the use of virus-like particles (VLPs) has become standard in vaccine design. The pEAQ-HT vector derived from the cowpea mosaic virus – based CPMV-HT expression system has been shown to allow the production of large amounts of recombinant proteins, including VLPs, in Nicotiana benthamiana. Moreover, previous work demonstrated that a tandem fusion of the core antigen (HBcAg) of hepatitis B virus (HBV) could direct the formation of core-like particles (CLPs) in plants. The work presented here demonstrated that the tandem core system is better suited for the plant-based production of CLPs presenting foreign antigens than SplitCore technology. It was shown that tandem core technology allows the plant-based production of CLPs which are suitable for the presentation of antigens either via chemical coupling or through antibody-antigen interactions. Of particular significance was the successful display of single domain antibody fragments of camelid origin (nanobodies, or VHH). The resulting “tandibody” particles, as they are named here, can bind to their cognate antigen to yield CLPs covered in the antigen of interest. Furthermore, it was shown that target antigens can be attached to CLPs via a fusion partner, raising the possibility of the development of a universal generic antigen-display platform. In addition to the transient expression work on HBcAg, lines of stably transformed N. benthamiana were created which constitutively expressed human gastric lipase (hGL), an enzyme of medical importance. In the future, this approach could be used to create transgenic plants constitutively expressing a universal tandibody, thus obviating the need for infiltration

Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north polar region of Mars

High-Resolution Imaging Science Experiment (HiRISE) imagery of the central Olympia Undae Dune Field in the north polar region of Mars shows a reticulate dune pattern consisting of two sets of nearly orthogonal dune crestlines, with apparent slipfaces on the primary crests, ubiquitous wind ripples, areas of coarse-grained wind ripples, and deflated interdune areas. Geomorphic evidence and dune field pattern analysis of dune crest length, spacing, defect density, and orientation indicates that the pattern is complex, representing two constructional generations of dunes. The oldest and best-organized generation forms the primary crestlines and is transverse to circumpolar easterly winds. Gross bed form-normal analysis of the younger pattern of crestlines indicates that it emerged with both circumpolar easterly winds and NE winds and is reworking the older pattern. Mapping of secondary flow fields over the dunes indicates that the most recent transporting winds were from the NE. The younger pattern appears to represent an influx of sediment to the dune field associated with the development of the Olympia Cavi reentrant, with NE katabatic winds channeling through the reentrant. A model of the pattern reformation based upon the reconstructed primary winds and resulting secondary flow fields shows that the development of the secondary pattern is controlled by the boundary condition of the older dune topography

A hybrid LES/CAA method applied to a 3D shear flow simulation

An aero-acoustic coupling method based on the splitting into noise sources generation and acoustic propagation in separate physical domains is presented in this paper. The key idea is to limit, as much as possible, the CFD domain to the noise generation region and to accurately propagate the acoustic waves with a CAA solver. The approach presented hereis a domain decomposition method based on the coupling of different equations, methods and meshes, which allows a simulation of both flow and acoustics in one single coupled calculation suitable for far field predictions with reflecting bodies through a coupling boundary

How To Characterise Performance In Engineering Freshmen’s Modelling Tasks?

This paper presents a study aiming at characterising engineering freshmen’s performance in modelling tasks, as well as the strategies they adopt to execute them, before and after taking a 3-D modelling course. 97 freshmen in a French engineering school were asked to produce 3-D models of a part, using three views and the product development platform Onshape. The accuracy of their models was assessed using geometrical, dimensional and functional criteria. The students’ performance was also investigated with regards to their modelling strategies. We characterised more specifically the strategies they adopted to constrain the overall length of the part, and pierce the central key groove. We complemented this experiment with spatial visualisation and spatial orientation tests, to explore the potential relation between modelling performance and spatial ability. We identified two strategies for piercing the key groove and three for defining the total length of the part. We observed that the latter was linked to the students’ spatial ability, unlike the key groove piercing strategy. We observed a significant increase in the number of students who adopted an efficient strategy to define the length of the part after the 3-D modelling course. This increase seems to indicate that more students were able to take into account visual information regarding size. We nevertheless observed a lack of progression in the ability to dimension this element accurately. This confirms the unchanging need for teaching students, as well as pupils, how to read and interpret 2-D information

Ozone isotopic composition: an angular effect in scattering processes?

International audienceThe ratio of the differential scattering cross sections involving distinguishable and indistinguishable isotopes may exhibit non-mass dependent angular variations. A numerical application of this hypotheses to the ozone reaction rates reproduces some of the results observed in laboratory experiments. This theory could be tested through a cross beam experiment where the isotopic composition of the scattered products is recorded as a function of their scattering angles