Refine
Year of publication
- 2024 (234)
- 2023 (1341)
- 2022 (2450)
- 2021 (2435)
- 2020 (2819)
- 2019 (2590)
- 2018 (2819)
- 2017 (2525)
- 2016 (2358)
- 2015 (2172)
- 2014 (1892)
- 2013 (2109)
- 2012 (1999)
- 2011 (2047)
- 2010 (1445)
- 2009 (1835)
- 2008 (1363)
- 2007 (1396)
- 2006 (1807)
- 2005 (1956)
- 2004 (2021)
- 2003 (1553)
- 2002 (1354)
- 2001 (1425)
- 2000 (1686)
- 1999 (1852)
- 1998 (1690)
- 1997 (1541)
- 1996 (1557)
- 1995 (1473)
- 1994 (1031)
- 1993 (405)
- 1992 (255)
- 1991 (169)
- 1990 (16)
- 1989 (28)
- 1988 (22)
- 1987 (23)
- 1986 (16)
- 1985 (12)
- 1984 (15)
- 1983 (31)
- 1982 (10)
- 1981 (9)
- 1980 (10)
- 1979 (15)
- 1978 (9)
- 1977 (12)
- 1976 (7)
- 1975 (3)
- 1974 (2)
- 1973 (2)
- 1972 (2)
- 1971 (2)
- 1970 (1)
- 1958 (1)
Document Type
- Article (35853)
- Doctoral Thesis (6499)
- Monograph/Edited Volume (5562)
- Postprint (3296)
- Review (2291)
- Part of a Book (1069)
- Other (922)
- Preprint (567)
- Conference Proceeding (551)
- Part of Periodical (527)
Language
- English (30820)
- German (26073)
- Spanish (363)
- French (330)
- Italian (115)
- Russian (112)
- Multiple languages (70)
- Hebrew (36)
- Portuguese (25)
- Polish (24)
Keywords
- Germany (202)
- climate change (183)
- Deutschland (142)
- machine learning (87)
- European Union (79)
- diffusion (78)
- Sprachtherapie (77)
- Migration (74)
- morphology (74)
- Logopädie (73)
Institute
- Institut für Biochemie und Biologie (5472)
- Institut für Physik und Astronomie (5442)
- Institut für Geowissenschaften (3668)
- Institut für Chemie (3484)
- Wirtschaftswissenschaften (2645)
- Historisches Institut (2515)
- Department Psychologie (2352)
- Institut für Mathematik (2150)
- Institut für Romanistik (2108)
- Sozialwissenschaften (1883)
Laboratory spectral measurements of relevant analogue materials were performed in the framework of the Rosetta mission in order to explain the surface spectral properties of comet 67P. Fine powders of coal, iron sulphides, silicates and their mixtures were prepared and their spectra measured in the Vis-IR range. These spectra are compared to a reference spectrum of 67P nucleus obtained with the VIRTIS/Rosetta instrument up to 2.7 mu m, excluding the organics band centred at 3.2 mu m. The species used are known to be chemical analogues for cometary materials which could be present at the surface of 67P. Grain sizes of the powders range from tens of nanometres to hundreds of micrometres. Some of the mixtures studied here actually reach the very low reflectance level observed by VIRTIS on 67P. The best match is provided by a mixture of sub-micron coal, pyrrhotite, and silicates. Grain sizes are in agreement with the sizes of the dust particles detected by the GIADA, MIDAS and COSIMA instruments on board Rosetta. The coal used in the experiment is responsible for the spectral slope in the visible and infrared ranges. Pyrrhotite, which is strongly absorbing, is responsible for the low albedo observed in the NIR. The darkest components dominate the spectra, especially within intimate mixtures. Depending on sample preparation, pyrrhotite can coat the coal and silicate aggregates. Such coating effects can affect the spectra as much as particle size. In contrast, silicates seem to play a minor role. (c) 2017 Elsevier Inc. All rights reserved.
Geophysical datasets sensitive to different physical parameters can be used to improve resolution of Earth's internal structure. Herein, we jointly invert long-period magnetotelluric (MT) data and surface-wave dispersion curves. Our approach is based on a joint inversion using a genetic algorithm for a one-dimensional (1-D) isotropic structure, which we extend to 1-D anisotropic media. We apply our new anisotropic joint inversion to datasets from Central Germany demonstrating the capacity of our joint inversion algorithm to establish a 1-D anisotropic model that fits MT and seismic datasets simultaneously and providing new information regarding the deep structure in Central Germany. The lithosphere/asthenosphere boundary is found at approx. 84 km depth and two main anisotropic layers with coincident most conductive/seismic fast-axis direction are resolved at lower crustal and asthenospheric depths. We also quantify the amount of seismic and electrical anisotropy in the asthenosphere showing an emerging agreement between the two anisotropic coefficients.
In areas characterized by many volcanoes, identifying the source of a deposit may not be trivial. This becomes much more complicated when looking for the source of a debris avalanche deposit (DAD), the common products of catastrophic volcanic edifice collapses. To overcome this problem, in this work a methodology is proposed based on the integration of texture features and areal distribution of the deposit, comparison between the petrography of the coarser clasts within the DAD and of the proximal products, grain-size analysis, and the volumetric estimations of the deposit and the volume missing from the volcanic edifice. This methodology has been tested to a DAD occurred near the city of Ibarra (Imbabura Province; Northern Ecuador), having a controversial source. Two main volcanic edifice are located in proximity of the DAD, the Cubilche volcano (3826 m.a.s.l.), located immediately south of and east of the colossal dormant Imbabura volcano. The former displays a sharp horseshoe shaped scar towards the north and inside this post-collapse edifice, that we name old Cubilche volcano (OCV), is located the young Cubilche volcano (YCV) that refilled a portion of the collapse scar and partially covered the southern flank of the OCV. Detailed knowledge of Cubilche volcano is critical because of its close proximity and interspersed activity with Imbabura volcano. In fact, Imbabura most recent edifice was built over the northwestern slope of the OCV and partially covered it. Recent studies linked the studied DAD to both Imbabura volcano as a product of its northern sector collapse, as well as neighboring Cubilche volcano. Our data points to Cubilche as the most likely source for this DAD. A perspective view of the shaded relief image of the present day OCV shows that the morphology of the volcano is well-preserved on its southern, eastern, and western flanks. This allows us to reconstruct the morphology of the OCV previous to the collapse through interpolation of elevation and altitude data of preserved flanks. A DEM of the present day topography was used for extrapolating the morphology. Using similar methodology, the post collapse base of the amphitheater was reconstructed by removing the relief of the present day YCV. The reconstructed topography of the OCV shows that it could have been a symmetric cone, reaching a maximum elevation of similar to 4100 m.a.s.l. with a lack volume of similar to 3.5 km(3). Based on this scenario, the deposit originated from the OCV main collapse should have a volume >3-3.5 km(3) in accordance to the volume calculated for the studied DAD. (C) 2018 Elsevier B.V. All rights reserved.
Coordination of the trunk and hips is crucial for successful dynamic balance in many activities of daily living. Persons with recurrent low back pain (rLBP), both while symptomatic and during periods of symptom remission, exhibit dysfunctional muscle activation patterns and coordination of these joints. In a novel dynamic balance task where persons in remission from rLBP exhibit dissociated trunk motion, it is unknown how trunk and hip musculature are coordinated. Activation of hip and trunk muscles were acquired from nineteen persons with and without rLBP during the Balance-Dexterity Task, which involves balancing on one limb while compressing an unstable spring with the other. There were no between-group differences in activation amplitude for any muscle groups tested. In back-healthy control participants, hip and trunk muscle activation amplitudes increased proportionally in response to the added instability of the spring (R = 0.837, p < 0.001). Increases in muscle activation amplitudes in the group in remission from rLBP were not proportional (R = 0.113, p = 0.655). Instead, hip muscle activation in this group was associated with task performance, i.e. dexterous control of the spring (R = 0.676, p = 0.002). These findings highlight atypical coordination of hip and trunk musculature potentially related to task demands in persons with rLBP even during remission from pain.
Microbial communities can subsist at depth in marine sediments without fresh supply of organic matter for millions of years. At threshold sedimentation rates of 1 millimeter per 1000 years, the low rates of microbial community metabolism in the North Pacific Gyre allow sediments to remain oxygenated tens of meters below the sea floor. We found that the oxygen respiration rates dropped from 10 micromoles of O-2 liter(-1) year(-1) near the sediment-water interface to 0.001 micromoles of O-2 liter(-1) year(-1) at 30-meter depth within 86 million-year-old sediment. The cell-specific respiration rate decreased with depth but stabilized at around 10(-3) femtomoles of O-2 cell(-1) day(-1) 10 meters below the seafloor. This result indicated that the community size is controlled by the rate of carbon oxidation and thereby by the low available energy flux.
I-III-VI2 semiconductor nanocrystals have been applied to a host of energy conversion devices with great success. Large scale implementation of device concepts based on these materials has, however, been somewhat stymied by the strong role of defects in determining the optoelectronic characteristics of these materials. Here we present a perspective view of the role of electronic structure and defects on the physical properties, particularly the spectroscopy, of this family of materials. Applications of these materials are further discussed in this context.
We study the properties of energy spreading in a lattice of elastically colliding harmonic oscillators (Ding-Dong model). We demonstrate that in the regular lattice the spreading from a localized initial state is mediated by compactons and chaotic breathers. In a disordered lattice, the compactons do not exist, and the spreading eventually stops, resulting in a finite configuration with a few chaotic spots.