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With the recent improvements in dynamic range of He-surface scattering experiments, the measurement of diffuse scattered intensity from surface defects: step edges or point defects: has become a frequently executable experiment. There remain, however, certain features in the experimental data that, to date, have not been fully explained. A calculational method applicable to the scattering from step edges is developed here, firstly to calculate the basic oscillatory form of the intensities, and then to look at the previously unexplained finer structure. In particular, the paper attempts to reproduce some experimental data; that is, helium-atom scattering from a randomly stepped Pt(111) crystal, in a fixed 90/sup 0/-angle geometry (see A. M. Lahee, J. R. Manson, J. P. Toennies, and Ch. Woell, Phys. Rev. Lett. 57, 471 (1986)). Even under a simple, hard-wall, eikonal approximation some of the previously unexplained features can be reproduced by the inclusion of a ''natural periodicity'' corrugation in the neighborhood of a step. This corrugation, with the periodicity of the lattice parameter, is allowed to decay away from the step. It is this decay length that is found to determine the characteristic width of the fine structure. The diffuse diffraction from a randomly stepped Pt(111), incidentally, now exhibits a certain degree of threefold symmetry. The enhanced corrugation amplitude in the neighborhood of a step is believed to be, of order at least, six times that observed on an unstepped Pt(111) surface. However, this enhancement factor is certainly very surface-orientation, and/or material, dependent.
Knapp, Sibylle; Gilli, Adrian; Anselmetti, Flavio S.; Hajdas, Irka
Lateglacial and Holocene rock-slope failures occur often as multistage failures where paraglacial adjustment and stress adaptation are hypothesised to control stages of detachment. However, we have only limited datasets to reconstruct detailed stages of large multistage rock-slope failures, and still aim at improving our models in terms of geohazard assessment. Here we use lake sediments, well-established for paleoclimate and paleoseismological reconstruction, with a focus on the reconstruction of rock-slope failures. We present a unique inventory from Lake Oeschinen (Bernese Alps, Switzerland) covering about 2.4 kyrs of rock-slope failure history. The lake sediments have been analysed using sediment-core analysis, radiocarbon dating and seismic-to-core and core-to-core correlations, and these were linked to historical and meteorological records. The results imply that the lake is significantly younger than the ~9 kyrs old Kandersteg rock avalanche (Tinner et al., 2005) and shows multiple rock-slope failures, two of which could be C14-dated. Several events detached from the same area potentially initiated by prehistoric earthquakes (Monecke et al., 2006) and later from stress relaxation processes. The data imply unexpected short recurrence rates that can be related to certain detachment scarps and also help to understand the generation of a historical lake-outburst flood. Here we show how polymethodical analysis of lake sediments can help to decipher massive multistage rock-slope failure. References Monecke, K., Anselmetti, F.S., Becker, A., Schnellmann, M., Sturm, M., Giardini, D., 2006. Earthquake-induced deformation structures in lake deposits: A Late Pleistocene to Holocene paleoseismic record for Central Switzerland. Eclogae Geologicae Helvetiae, 99(3), 343-362. Tinner, W., Kaltenrieder, P., Soom, M., Zwahlen, P., Schmidhalter, M., Boschetti, A., Schlüchter, C., 2005. Der nacheiszeitliche Bergsturz im Kandertal (Schweiz): Alter und Auswirkungen auf die
Delzor, Aurélie; Couratier, Philippe; Boumédiène, Farid; Nicol, Marie; Druet-Cabanac, Michel; Paraf, François; Méjean, Annick; Ploux, Olivier; Leleu, Jean-Philippe; Brient, Luc; Lengronne, Marion; Pichon, Valérie; Combès, Audrey; El Abdellaoui, Saïda; Bonneterre, Vincent; Lagrange, Emmeline; Besson, Gérard; Bicout, Dominique J; Boutonnat, Jean; Camu, William; Pageot, Nicolas; Juntas-Morales, Raul; Rigau, Valérie; Masseret, Estelle; Abadie, Eric; Preux, Pierre-Marie; Marin, Benoît
Introduction Amyotrophic lateral sclerosis (ALS) is the most common motor neurone disease. It occurs in two forms: (1) familial cases, for which several genes have been identified and (2) sporadic cases, for which various hypotheses have been formulated. Notably, the β-N-methylamino-L-alanine (L-BMAA) toxin has been postulated to be involved in the occurrence of sporadic ALS. The objective of the French BMAALS programme is to study the putative link between L-BMAA and ALS. Methods and analysis The programme covers the period from 1 January 2003 to 31 December 2011. Using multiple sources of ascertainment, all the incident ALS cases diagnosed during this period in the area under study (10 counties spread over three French regions) were collected. First, the standardised incidence ratio will be calculated for each municipality under concern. Then, by applying spatial clustering techniques, overincidence and underincidence zones of ALS will be sought. A case–control study, in the subpopulation living in the identified areas, will gather information about patients’ occupations, leisure activities and lifestyle habits in order to assess potential risk factors to which they are or have been exposed. Specimens of drinking water, food and biological material (brain tissue) will be examined to assess the presence of L-BMAA in the environment and tissues of ALS cases and controls. Ethics and dissemination The study has been reviewed and approved by the French ethical committee of the CPP SOOM IV (Comité de Protection des Personnes Sud-Ouest & Outre-Mer IV). The results will be published in peer-reviewed journals and presented at national and international conferences. PMID:25180055
Manson, Joseph R.
Professor J Peter Toennies of the Max-Planck-Institut für Strömungsforschung in Göttingen, Germany (now the Max-Planck-Institut für Dynamik und Selbstorganization). Toennies was already, at that time, a major figure in the areas of physics and chemistry that use molecular and atomic beams. This was just a few years after he, with graduate student Bruce Doak, had succeeded in the first measurements of surface specific phonons using He atom scattering and, in particular, had obtained complete dispersion relations for Rayleigh modes. This was precisely the type of experiment that Celli, Cabrera and I had suggested over a decade earlier, so our research interests were an excellent match. Our work that summer with graduate student Christof Wöll and postdoc Angela Lahee developed experimental and theoretical methods for measuring the presence of isolated atomic or molecular adsorbates on surfaces. This initial visit led to a long and productive period of research on many aspects of He atom scattering from surfaces, and almost every summer from then through 1997 was spent in the very pleasant and historic city of Göttingen, which still has visible roman ruins and many old German buildings dating from the 1500s. This period was marked by interactions and collaborations with many of the graduate students, postdocs and visitors to the Toennies lab. Many of these collaborations continue to some extent even today, and include work with Andrew Graham, John Ellis, Frank Hofmann, Massimo Bertino, Robert Grisenti, Alexi Glebov, Wieland Schöllkopf, Walter Silvestri and Horst-Günter Rubahn. It was also during this period that I developed a long friendship and scientific collaboration with Jim Skofronick and Sanford Safron of the Department of Physics at Florida State University. Both were frequent visitors to the Toennies laboratory, and our collaboration extended far beyond our overlapping stays there. Among the fondest memories of visits to Göttingen are the many long walks and