Semi-quantitative analysis of bulk chondritic material using X-Ray fluorescence spectroscopy

73rd Annual Meeting of the Meteoritical-Society, New York, NY, July 26-30, 2010International audienceSynchrotron radiation X-ray fluorescence (SR-XRF) is a method of choice to analyze fragile, unique meteoritic samples, requiring no sample preparation. It is a nondestructive, multielemental, quantitative method, easily coupled to diffraction and speciation for a detailed sample characterization. The composition of samples thicker than a few microns is however difficult to obtain due to the high attenuation of the characteristic X-rays resulting in non-detection of low-Z elements (Z≤ 14)

Holographic Methods as Local Probes of the Atomic Order in Solids

In the last fifteen years several techniques based on the holographic principle have been developed for the study of the 3D local order in solids. These methods use various particles: electrons, hard x-ray photons, gamma photons, or neutrons to image the atoms. Although the practical realisation of the various imaging experiments is very different, there is a common thread; the use of inside reference points for holographic imaging. In this paper we outline the basics of atomic resolution holography using inside reference points, especially concentrating to the hard x-ray case. Further, we outline the experimental requirements and what has been practically realized in the last decade. At last we give examples of applications and future perspectives.Comment: 14 pages, 6 figure

Математическая психология

The article is devoted to mathematical psychology. The processes associated with the emergence of mathematical psychology and its stages. Definition of the problem of limited modeling capabilities with the help of this psychology. We consider in this article are still major areas of mathematical professor psychology V.Krylov (he played a leading role in the development of mathematical psychology)

The influence of forest reserve protection on the structure, stability, and functioning of dung-associated invertebrate communities

Communities are influenced by many factors, with anthropogenic impacts being one of the strongest. These factors can influence community structure and may cause non-random species loss by filtering certain traits of species, which may also determine how a species contributes to ecosystem functioning. The structure of a community can also be highly variable over short timescales and across seasons, as abiotic factors can alter a resource over the course of days and also alter intensity of competition within a community. These short-timescale influences are most noticeable in an ephemeral resource that is limited in both space and time. Changes in community structure and interactions can be represented as networks of interactions (links) among species (nodes). Interaction networks describe a community and incorporate non-trophic interactions, which can alter their structure. These are generally measured by counting the number of trophic interactions, ignoring non-trophic interactions such as competition. However, competitive interactions may be important for network dynamics, yet the most appropriate way to quantify competition remains unclear. The outcome of a competitive interaction could potentially be predicted by the body size ofcompeting individuals, and this would remove the need to observe individual interactions. These ideas were tested using the dung-associated community in an Afromontane forest reserve in Nigeria across variation in seasons and in areas that were protected from anthropogenic impacts by fencing. Trapping and recording of interactions within the community was used to assess community structure, and experiments were run to test how dung removal and secondary seed dispersal changed across seasons and in protected areas of the forest. The influence of competition was determined by altering the size and number of dung beetles present at the resource. The community structure was influenced by forest protection and varied across seasons. Additionally, the size and number of dung beetles present was higher in protected areas in the wet season, resulting in higher dung removal and secondary seed dispersal and indicating non-random species loss in unprotected areas. The attractiveness of the dung resource changed over short timescales and desiccation occurred rapidly in the dry season, which resulted in decreased insect abundance and diversity over the course of days. Individual dung removal rates were not additive, and could only be used to predict community-level dung removal when taking into account competitive interactions. The body-size ratio between winners and losers of a competition was a good predictor of an interaction outcome. Competition networks were highly connected and nested, with compartmentalisation occurring in the competition network. At the community level, effects of forest protection and changing seasons only altered network nestedness. Therefore, body size can be used to predict species responses to anthropogenic threats and community structure and function when taking into account density-dependent competitive interactions. Furthermore, when determining community responses to anthropogenic threats, sampling across changes in seasons and observing competitive interactions provides more information about a community structure and stability

Preliminary Examination of the Interstellar Collector of Stardust

The findings of the Stardust spacecraft mission returned to earth in January 2006 are discussed. The spacecraft returned two unprecedented and independent extraterrestrial samples: the first sample of a comet and the first samples of contemporary interstellar dust. An important lesson from the cometary Preliminary Examination (PE) was that the Stardust cometary samples in aerogel presented a technical challenge. Captured particles often separate into multiple fragments, intimately mix with aerogel and are typically buried hundreds of microns to millimeters deep in the aerogel collectors. The interstellar dust samples are likely much more challenging since they are expected to be orders of magnitudes smaller in mass, and their fluence is two orders of magnitude smaller than that of the cometary particles. The goal of the Stardust Interstellar Preliminary Examination (ISPE) is to answer several broad questions, including: which features in the interstellar collector aerogel were generated by hypervelocity impact and how much morphological and trajectory information may be gained?; how well resolved are the trajectories of probable interstellar particles from those of interplanetary origin?; and, by comparison to impacts by known particle dimensions in laboratory experiments, what was the mass distribution of the impacting particles? To answer these questions, and others, non-destructive, sequential, non-invasive analyses of interstellar dust candidates extracted from the Stardust interstellar tray will be performed. The total duration of the ISPE will be three years and will differ from the Stardust cometary PE in that data acquisition for the initial characterization stage will be prolonged and will continue simultaneously and parallel with data publications and release of the first samples for further investigation

Non-desctructive X-Ray, Raman and IR Imaging of quarantined Mars return samples

73rd Annual Meeting of the Meteoritical-Society : New York, NY, July 26-30, 2010International audienceIn preparation for the upcoming international Mars Sample Return mission, bringing to Earth samples containing potential biohazards, we have implemented a hyperspectral method of analysis of grains performed in BSL4 quarantine conditions,by combining several non-destructive imaging diagnostics. This methodology was tested on meteorites [1, 2] and cometary grains from the recent NASA Stardust mission [3-6]