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Reflections on a Geometry of Processes
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32919.pdf (publisher's version ) (Open Access)Algebraic Process Calcul
Seismic characteristics of sediment drifts: An example from the Agulhas Plateau, southwest Indian Ocean
Sediment drifts provide information on the palaeoceanographic development of a region. Additionally, they may represent hydrocarbon reservoirs. Because of this, sediment drift investigation has increased over the last few years. Nevertheless, a number of problems remain regarding the processes controlling their shape, the characteristic lithological and seismic patterns and the diagnostic criteria.As an example, sediment drifts from the Agulhas Plateau, southwest Indian Ocean, are presented here. They show a variety of seismic features and facies including an asymmetric mounded geometry, changes in internal reflection pattern, truncation of internal reflectors at the seafloor and discontinuities. This collection of observations in combination with the local oceanography appears to comprise a diagnostic tool for sediment drifts
The role of GPR techniques in determining ice cave properties: Peña Castil ice cave, Picos de Europa
ProducciĂłn CientĂficaThe structure and ice content of ice caves are poorly understood. Ground penetrating radar (GPR) can provide useful insights but has only rarely been applied to ice caves. This paper interprets GPR images (radargrams) in terms of internal structure, stratification, compaction, thickness and volume of the ice block in the Peña Castil ice cave (Central Massif of Picos de Europa, northern Spain), providing the endokarst geometry of the ice cave in GPR data reflections. Eight radargrams were obtained by applying a shielded groundâcoupled antenna with a nominal frequency of 400âMHz. Although the radargrams do not depict the iceâbasal bedrock interface, they suggest that the ice block is at least 54âm deep and similarly thick. Some curved reflection signatures suggest a potential vertical displacement in the block of ice, and thus certain dynamics in the ice body. Other images show numerous interbedded clasts and thin sediment layers imaged as banded reflections. In this particular cave a direct visual inspection of the ice stratigraphy is a difficult task but GPR provides clear reflectivity patterns of some of its internal features, making GPR a suitable instrument for this and future studies to achieve a better and broader understanding of the internal behavior of ice caves.Ministerio de EconomĂa, Industria y Competitividad (project CGL2015-68144-R)Ministerio de Agricultura y Pesca, AlimentaciĂłn y Medio Ambiente (project OAPN-053/2010
Temperature induced structural changes in even-odd nylons with long polymethylene segments
Structural transitions of nylons 8 9 and 12 9 heating and cooling processes were investigated using calorimetric, spectroscopic during and real time X-ray diffraction data. These even-odd nylons had three polymorphic forms related to structures where hydrogen bonds were established in two planar directions. Heating processes showed a first structural transition at low temperature where the two strong reflections related to the packing mode of the low temperature structure (form I) disappeared instead of moving together and merging into a single reflection, as observed for conventional even-even nylons. The high temperature structure corresponded to a typical pseudohexagonal packing (form III) attained after the named Brill transition temperature. Structural transitions were not completely reversible since an intermediate structure (form II) became clearly predominant at room temperature in subsequent cooling processes. A single spherulitic morphology with negative birefringence and a flat-on edge-on lamellar disposition was obtained when the two studied polyamides crystallized from the melt state. Kinetic analyses indicated that both nylons crystallized according to a single regime and a thermal nucleation. Results also pointed out a secondary nucleation constant for nylon 12 9 higher than that for nylon 8 9, suggesting greater difficulty in crystallizing when the amide content decreased. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2494â2506Peer ReviewedPostprint (author's final draft
Majorana Fermion Induced Non-local Current Correlations in Spin-orbit Coupled Superconducting Wires
Recent observation of zero bias conductance peaks in semiconductor
wire/superconductor heterostructures has generated great interest, and there is
a hot debate on whether the observation is associated with Majorana fermions
(MFs). Here we study the local and crossed Andreev reflections in a junction of
two normal leads and a sandwiched superconductor-semiconductor wire with two
spatially separated but strongly coupled MF end states. The conductance and
Fano factors of such a device are sharply different from the topologically
trivial case even in the presence of disorder, and can hence be used to
identify MFs unambiguously.Comment: 7+ pages, 10 figure
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