Bocchiola D.,Polytechnic of Milan |
Diolaiuti G.,University of Milan |
Soncini A.,Polytechnic of Milan |
Mihalcea C.,University of Milan |
And 5 more authors.
Hydrology and Earth System Sciences | Year: 2011
In the mountain regions of the Hindu Kush, Karakoram and Himalaya (HKH) the "third polar ice cap" of our planet, glaciers play the role of "water towers" by providing significant amount of melt water, especially in the dry season, essential for agriculture, drinking purposes, and hydropower production. Recently, most glaciers in the HKH have been retreating and losing mass, mainly due to significant regional warming, thus calling for assessment of future water resources availability for populations down slope. However, hydrology of these high altitude catchments is poorly studied and little understood. Most such catchments are poorly gauged, thus posing major issues in flow prediction therein, and representing in fact typical grounds of application of PUB concepts, where simple and portable hydrological modeling based upon scarce data amount is necessary for water budget estimation, and prediction under climate change conditions. In this preliminarily study, future (2060) hydrological flows in a particular watershed (Shigar river at Shigar, ca. 7000 km2), nested within the upper Indus basin and fed by seasonal melt from major glaciers, are investigated. The study is carried out under the umbrella of the SHAREPaprika project, aiming at evaluating the impact of climate change upon hydrology of the upper Indus river. We set up a minimal hydrological model, tuned against a short series of observed ground climatic data from a number of stations in the area, in situ measured ice ablation data, and remotely sensed snow cover data. The future, locally adjusted, precip-itation and temperature fields for the reference decade 2050- 2059 from CCSM3 model, available within the IPCC's panel, are then fed to the hydrological model. We adopt four different glaciers' cover scenarios, to test sensitivity to decreased glacierized areas. The projected flow duration curves, and some selected flow descriptors are evaluated. The uncertainty of the results is then addressed, and use of the model for nearby catchments discussed. The proposed approach is valuable as a tool to investigate the hydrology of poorly gauged high altitude areas, and to project forward their hydrological behavior pending climate change. © Author(s) 2011.
Cicha I.,Friedrich - Alexander - University, Erlangen - Nuremberg |
Worner A.,Friedrich - Alexander - University, Erlangen - Nuremberg |
Urschel K.,Friedrich - Alexander - University, Erlangen - Nuremberg |
Beronov K.,Bavarian Academy of science |
And 4 more authors.
Stroke | Year: 2011
Background and Purpose: Rupture of atherosclerotic plaques is one of the main causes of ischemic strokes. The aim of this study was to investigate carotid plaque vulnerability markers in relation to blood flow direction and the mechanisms leading to plaque rupture at the upstream side of carotid stenoses. Methods: Frequency and location of rupture, endothelial erosion, neovascularization, and hemorrhage were determined in longitudinal sections of 80 human carotid specimens. Plaques were immunohistochemically analyzed for markers of vulnerability. Plaque geometry was measured to reconstruct shape profiles of ruptured versus stable plaques and to perform computational fluid dynamics analyses. Results: In 86% of ruptured plaques, rupture was observed upstream. In this region, neovascularization and hemorrhage were increased, along with increased immunoreactivity of vascular endothelial and connective tissue growth factor, whereas endothelial erosion was more frequent downstream. Proteolytic enzymes, mast cell chymase and cathepsin L, and the proapoptotic protein Bax showed significantly higher expression upstream as compared with the downstream shoulder of atherosclerotic lesions. Comparison of geometric profiles for ruptured and stable plaques showed increased longitudinal asymmetry of fibrous cap and lipid core thickness in ruptured plaques. The specific geometry of plaques ruptured upstream induced increased levels of shear stress and increased pressure drop between the upstream and the downstream plaque shoulders. Conclusions: Vulnerability of the upstream plaque region is associated with enhanced neovascularization, hemorrhage, and cap thinning induced by proteolytic and proapoptotic mechanisms. These processes are reflected in structural plaque characteristics, analyses of which could improve the efficacy of vascular diagnostics and prevention. © 2011 American Heart Association, Inc.
Lerf A.,Bavarian Academy of science |
Wagner F.E.,TU Munich
Hyperfine Interactions | Year: 2016
Ferrogallic inks were used for at least two millennia before they became obsolete in the 20th century. The chemistry of such inks is, however, still largely unclear. Today it is of particular interest for the conservation of old manuscripts. 57Fe Mössbauer spectra of the ink on historical documents showed the presence of Fe(II) oxalate and of Fe(III) sites presumably representing iron oxihydroxides. To obtain more information on the behaviour of ink on paper we have performed Mössbauer studies at 300 and 4.2 K on iron gall inks prepared from FeSO4⋅7H2O and tannin. These inks were either written on paper or isolated as a precipitate by centrifugation. In the dried precipitate there is still a strong contribution of the FeSO4⋅7H2O which is absent in the same ink written on paper, for which a broad ferrous component with a quadrupole splitting (QS) of about 2.5 mm/s was found. The dominant Fe(III) site present in all inks on paper with QS ≈ 0.82 mm/s is not Fe(III) gallate and different from the precipitates. We propose that nanoparticulate oxidic clusters or molecular composites covered by a shell of polymerized oxidation products of the phenols are formed on the paper. © 2016, Springer International Publishing Switzerland.
Mayer C.,Bavarian Academy of science |
Fowler A.C.,University of Limerick |
Lambrecht A.,University of Innsbruck |
Scharrer K.,University of Swansea
Journal of Glaciology | Year: 2011
Between 2003 and 2007, North Gasherbrum Glacier on the northeastern slope of the Karakoram mountains in Asia underwent a dramatic acceleration, during which a velocity wave propagated down the glacier. There was a significant transfer of ice from up-glacier downstream, which resulted in a strong surface elevation increase over the lower tongue, but only a moderate advance of the glacier snout. We interpret this behaviour as that of a glacier surge, and we explain the observations by means of a simple version of the Kamb drainage-switching theory.
Krukau A.,Max Planck Institute of Colloids and Interfaces |
Krukau A.,Bavarian Academy of science |
Knecht V.,Max Planck Institute of Colloids and Interfaces |
Knecht V.,Albert Ludwigs University of Freiburg |
Lipowsky R.,Max Planck Institute of Colloids and Interfaces
Physical Chemistry Chemical Physics | Year: 2014
Molecular motors such as kinesin are essential for many biological processes. These motors have two motor domains, which bind to tubulin filaments, hydrolyze ATP, and transduce the released chemical energy into directed movements. The general principles of this chemomechanical coupling are now well-established but the underlying molecular mechanisms remain elusive because small conformational changes within large proteins are difficult to detect experimentally. Here, we use atomistic molecular dynamics simulations to monitor such changes within a single motor domain of KIF1A, which belongs to the kinesin-3 motor family. The nucleotide binding pocket of this domain can be empty or occupied by ATP or ADP. For these three nucleotide states, we determine the mobility of the backbone of the protein, both in solution and attached to tubulin. Only one subdomain of the motor domain is found to exhibit a strongly increased mobility upon binding to tubulin: the neck linker that presumably acts as a mechanical transmitter to the other motor domain in dimeric kinesin-3 motors. Furthermore, upon binding to tubulin, the neck linker mobility becomes sensitive to the bound nucleotide and is highly increased after phosphate release, which implies undocking of this linker from the core of the motor domain. These simulation results are consistent with experimental data from EPR spectroscopy, FRET, and cryo-electron microscopy. A detailed analysis of our simulation data also reveals that the undocking of the neck linker in the ADP-kinesin-tubulin state arises from allosteric interactions between the nucleotide and tubulin and that the β-sheet core undergoes a twist both during phosphate release and ATP binding. The computational approach used here can be applied to other motor domains and mechanoenzymes in order to identify allosteric interactions between the subdomains of these proteins. This journal is © 2014 the Owner Societies.