Institute of Geodesy and Photogrammetry

Zürich, Switzerland

Institute of Geodesy and Photogrammetry

Zürich, Switzerland
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Newman A.V.,Georgia Institute of Technology | Stiros S.,University of Patras | Feng L.,Georgia Institute of Technology | Feng L.,Nanyang Technological University | And 9 more authors.
Geophysical Research Letters | Year: 2012

After approximately 60years of seismic quiescence within Santorini caldera, in January 2011 the volcano reawakened with a significant seismic swarm and rapidly expanding radial deformation. The deformation is imaged by a dense network of 19 survey and 5 continuous GPS stations, showing that as of 21 January 2012, the volcano has extended laterally from a point inside the northern segment of the caldera by about 140mm and is expanding at 180mm/yr. A series of spherical source models show the source is not migrating significantly, but remains about 4km depth and has expanded by 14 million m 3 since inflation began. A distributed sill model is also tested, which shows a possible N-S elongation of the volumetric source. While observations of the current deformation sequence are unprecedented at Santorini, it is not certain that an eruption is imminent as other similar calderas have experienced comparable activity without eruption. Copyright 2012 by the American Geophysical Union.

Moraes T.A.,University of Campinas | Barlow P.W.,University of Bristol | Klingele E.,Institute of Geodesy and Photogrammetry | Gallep C.M.,University of Campinas
Naturwissenschaften | Year: 2012

Semi-circadian rhythms of spontaneous photon emission from wheat seedlings germinated and grown in a constant environment (darkened chamber) were found to be synchronized with the rhythm of the local gravimetric (lunisolar) tidal acceleration. Time courses of the photon-count curves were also found to match the growth velocity profile of the seedlings. Pair-wise analyses of the data-growth, photon count, and tidal-by local tracking correlation always revealed significant coefficients (P>0.7) for more than 80% of any of the time periods considered. Using fast Fourier transform, the photon-count data revealed periodic components similar to those of the gravimetric tide. Time courses of biophoton emissions would appear to be an additional, useful, and innovative tool in both chronobiological and biophysical studies. © Springer-Verlag 2012.

Fisahn J.,Max Planck Institute of Molecular Plant Physiology | Klingele E.,Institute of Geodesy and Photogrammetry | Barlow P.,University of Bristol
Plant Signaling and Behavior | Year: 2015

The yield of chlorophyll fluorescence Ft was measured in leaves of Arabidopsis thaliana over periods of several days under conditions of continuous illumination (LL) without the application of saturating light pulses. After linearization of the time series of the chlorophyll fluorescence yield (∆ft), oscillations became apparent with periodicities in the circatidal range. Alignments of these linearized time series ∆Ft with the lunisolar tidal acceleration revealed high degrees of synchrony and phase congruence. Similar congruence with the lunisolar tide was obtained with the linearized quantum yield of PSII (∆ΦII), recorded after application of saturating light pulses. These findings strongly suggest that there is an exogenous timekeeper which is a stimulus for the oscillations detected in both the linearized yield of chlorophyll fluorescence ((∆ft) and the linearized quantum yield of PSII (∆ΦII). © 2015 Taylor & Francis Group, LLC.

Wessels M.,Institute For Seenforschung | Anselmetti F.,University of Bern | Artuso R.,Bundesamt fur Landestopografie Swisstopo | Baran R.,AirborneHydroMapping GmbH | And 12 more authors.
ZFV - Zeitschrift fur Geodasie, Geoinformation und Landmanagement | Year: 2015

Within the project "Tiefenschärfe - hochauflösende Vermessung Bodensee" a high-resolution seamless terrain model is created using airborne topobathymetric laserscanning and multibeam echosounder (MBES) techniques. The project visualizes the enormous wealth of features of underwater landscapes of lakes. The combination of hydroacoustic (multibeam echosounder) and laser-optic (topobathymetric laserscanning) methods was used for the first time in a freshwater body of this size. Opportunities, limitations and restrictions of these high-resolution methods are presented. © 2015, Wissner Verlag. All rights reserved.

Guillaume S.,Institute of Geodesy and Photogrammetry | Geiger A.,Institute of Geodesy and Photogrammetry | Forrer F.,Institute of Geodesy and Photogrammetry
International Association of Geodesy Symposia | Year: 2012

This paper presents a new method to detect small and rapid movements in real-time with a single L1-GPS receiver. The method is based on the prediction of single differences between satellites by appropriate Filter methods. The movements' detection is based, on the one hand, on displacements computed with multiple prediction lengths, and on the other hand, on the time series of displacements computed with the previous epochs. The accuracy of this method is demonstrated by real 10-[Hz] observations with two L1-receivers. One antenna remained completely static, while characteristic movements were applied on the other. This allow us to compare on the one hand the displacements of the displaced antenna estimated by G-MoDe with standard differential kinematic processing and on the other hand the resolution and the noise behavior of G-MoDe applied on the data of the static antenna. The results indicate that, in good conditions, horizontal movements and of short duration and oscillatory movements above 5 mm amplitude are significantly detected (95%). © Springer-Verlag Berlin Heidelberg 2012.

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