Implementation of e-science tools for complex analysis of human-environmental interaction

An e-science approach allows the integration of different data types to develop coherent analyses of past and expected impacts of natural and human caused environmental change and the corresponding impact on human population structures. Demographic analyses have been possible for some time both with and without the aid of computational tools, however, the implementation of e-science tools allow a more dynamic manipulation of scenarios drawing on actual social, economic and demographic data and correlating that with GIS spatial data. The resulting implementation allows us to generate 'snapshots' in time to reconstruct the impact of past events or hypothetical events. In this way, we can test the feasibility of data extraction from diverse data sources produced for different research programs in different disciplines. The research is driven not by an interest in technological development, but rather as one part of a general strategy designed to inform policy decisions in a situation with a number of methodological and practical constraints

Photometric Analysis of Recently Discovered Eclipsing Binary GSC 00008-00901

Photometric analysis of $BVR_C$ light curves of newly discovered eclipsing binary GSC 0008-00901 is presented. The orbital period is improved to 0.28948(11) days. Photometric parameters are determined, as well. The analysis yielded to conclusion that system is an over-contact binary of W UMa type with components not in thermal contact. The light curves from 2005 show the presence of a spot on the surface of one of the components, while light curves from 2006 are not affected by maculation.Comment: Accepted for publication in Astrophysics & Space Scienc

Mesoscopic Fluctuations in Quantum Dots in the Kondo Regime

Properties of the Kondo effect in quantum dots depend sensitively on the coupling parameters and so on the realization of the quantum dot -- the Kondo temperature itself becomes a mesoscopic quantity. Assuming chaotic dynamics in the dot, we use random matrix theory to calculate the distribution of both the Kondo temperature and the conductance in the Coulomb blockade regime. We study two experimentally relevant cases: leads with single channels and leads with many channels. In the single-channel case, the distribution of the conductance is very wide as $T_K$ fluctuates on a logarithmic scale. As the number of channels increases, there is a slow crossover to a self-averaging regime.Comment: 4 pages, 3 figure

Grinding of cement clinkers : linking multi-scale fracture properties to system chemistry, mineralogy and microstructure

Thesis (S.M.)--Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 162-172).Growing environmental concerns encourage the cement industry to improve its environmental performance, which in turn renews the interest in clinker grinding efficiency. Current knowledge on clinker grinding was built over the past decades, but contributions from fracture mechanics remained limited. This research aimed to contribute to this field by investigating industrial clinkers with innovative techniques such as multiscale microscratching and statistical electron-probe microanalysis (EPMA). Microstructure investigations were first performed with scanning electron microscopy (SEM), and three characteristic length scales were defined for clinkers: the nodules at the macroscale, the clinker matrix and porosity at the intermediate scale, and the clinker phases at the microscale. A statistical EPMA method was developed to allow simultaneous determination of the clinker bulk chemistry, the chemistry of the clinker phases, and their abundance. The microscratch test method was downscaled to measure the fracture properties at each characteristic scale of clinkers. Measurements on single silicate grains provided access to the intrinsic fracture toughness, which was three to four time lower than the macroscale fracture toughness. A combination of microstructure effects and toughening mechanisms (crack deflection, crack tip shielding by microcracks, crack trapping, and crack pinning) explained this behavior. Comparison of industrial clinkers showed that higher macroscale toughness (i.e., poor coarse grindability) was associated with oversized alite crystals, which was explained by the increase of microcracks toughening with larger grain size. In contrast, lower macroscale fracture toughness (i.e., better coarse grindability) was associated with either poorly burned clinkers showing excessive porosity or well burned clinkers having a good repartition of small silicates. However, difficulties in fine grinding were expected for the poorly burned clinkers because of the increased amounts of clustered belite. Overall, this thesis presents new experimental methods to investigate clinkers, as well as links between clinkers properties and grindability, both of which hold interest to the scientific community and the cement industry.by William Wilson.S.M

Kondo Effect of Quantum Dots in the Quantum Hall Regime

Quantum dots in the quantum Hall regime can have pairs of single Slater determinant states that are degenerate in energy. We argue that these pairs of many body states may give rise to a Kondo effect which can be mapped into an ordinary Kondo effect in a fictitious magnetic field. We report on several properties of this Kondo effect using scaling and numerical renormalization group analysis. We suggest an experiment to investigate this Kondo effect.Comment: To appear in Phys. Rev. B (5 pages, 4 figures); references added; several changes in tex

Very long optical path-length from a compact multi-pass cell

The multiple-pass optical cell is an important tool for laser absorption spectroscopy and its many applications. For most practical applications, such as trace-gas detection, a compact and robust design is essential. Here we report an investigation into a multi-pass cell design based on a pair of cylindrical mirrors, with a particular focus on achieving very long optical paths. We demonstrate a path-length of 50.31 m in a cell with 40 mm diameter mirrors spaced 88.9 mm apart - a 3-fold increase over the previously reported longest path-length obtained with this type of cell configuration. We characterize the mechanical stability of the cell and describe the practical conditions necessary to achieve very long path-lengths