Attenuation technique for measuring sediment displacement levels

A technique for obtaining accurate, high (spatial) resolution measurements of sediment redeposition levels is described. In certain regimes, the method may also be employed to provide measurements of sediment layer thickness as a function of time. The method uses a uniform light source placed beneath the layer, consisting of transparent particles, so that the intensity of light at a point on the surface of the layer can be related to the depth of particles at that point. A set of experiments, using the impact of a vortex ring with a glass ballotini particle layer as the resuspension mechanism, are described to test and illustrate the technique

Effect of cognitive abilities on crowdsourcing task performance

Abstract Matching crowd workers to suitable tasks is highly desirable as it can enhance task performance, reduce the cost for requesters, and increase worker satisfaction. In this paper, we propose a method that considers workers’ cognitive ability to predict their suitability for a wide range of crowdsourcing tasks. We measure cognitive ability via fast-paced online cognitive tests with a combined average duration of 6.2 min. We then demonstrate that our proposed method can effectively assign or recommend workers to five different popular crowd tasks: Classification, Counting, Proofreading, Sentiment Analysis, and Transcription. Using our approach we demonstrate a significant improvement in the expected overall task accuracy. While previous methods require access to worker history or demographics, our work offers a quick and accurate way to determine which workers are more suitable for which tasks

Structural studies of lipid based nanosystems for drug delivery: X-Ray Diffraction (XRD) and Cryogenic Transmission Electron Microscopy (cryo-TEM)

Lipid based nanosystems have potential use as matrixes able to dissolve and deliver active molecules in a controlled fashion, thereby improving their bioavailability and reducing side-effects. In particular nanoparticles based on lipids have been widely proposed as novel drug carrier systems. For instance solid lipid nanoparticles (SLN) join the advantages of colloidal lipid emulsions with those of solid matrix particles. The second generation of SLN is represented by nanostructured lipid carriers (NLC), which are composed of a solid lipid matrix with a certain content of a liquid lipid phase. Another type of lipid dispersion that can provide matrixes for the sustained release of drugs is represented by monooleine aqueous dispersions (MAD). MAD are heterogeneous systems generated by the dispersion of an amphiphilic lipid, such as monoolein, in water. They are constituted of complex lyotropic liquid crystalline nanostructures like micellar, lamellar, hexagonal, and cubic phases. In order to characterize nanosystems it is important to carry out detailed systematic investigations. X-ray diffraction and microscopy give informations about shape, inner structure and dimensions of powders and dispersions that could not otherwise be identified. This chapter provides an overview about the use of x-ray diffraction and cryogenic transmission electron microscopy as techniques for characterizing lipid nanosystems recently developed by our research group

The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Body Unit and Combined System Tests

The ChemCam instrument suite on the Mars Science Laboratory (MSL) rover Curiosity provides remote compositional information using the first laser-induced breakdown spectrometer (LIBS) on a planetary mission, and provides sample texture and morphology data using a remote micro-imager (RMI). Overall, ChemCam supports MSL with five capabilities: remote classification of rock and soil characteristics; quantitative elemental compositions including light elements like hydrogen and some elements to which LIBS is uniquely sensitive (e.g., Li, Be, Rb, Sr, Ba); remote removal of surface dust and depth profiling through surface coatings; context imaging; and passive spectroscopy over the 240-905 nm range. ChemCam is built in two sections: The mast unit, consisting of a laser, telescope, RMI, and associated electronics, resides on the rover's mast, and is described in a companion paper. ChemCam's body unit, which is mounted in the body of the rover, comprises an optical demultiplexer, three spectrometers, detectors, their coolers, and associated electronics and data handling logic. Additional instrument components include a 6 m optical fiber which transfers the LIBS light from the telescope to the body unit, and a set of onboard calibration targets. ChemCam was integrated and tested at Los Alamos National Laboratory where it also underwent LIBS calibration with 69 geological standards prior to integration with the rover. Post-integration testing used coordinated mast and instrument commands, including LIBS line scans on rock targets during system-level thermal-vacuum tests. In this paper we describe the body unit, optical fiber, and calibration targets, and the assembly, testing, and verification of the instrument prior to launch