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201.
Records from magnetic signals in Buenos Aires loess–paleosol sequences have been published, but their relationship with environmental
changes has been difficult to establish. Studies on the superparamagnetic (SP) population in present soils can help to understand
these processes. Samples from present soils (Argiudolls) and a paleosol from the Buenos Aires Province (Argentina) were analyzed
using low and room temperature magnetic measurements. They show that it is possible to support the hypothesis of a lognormal
distribution of superparamagnetic particles, the median diameter near 15 nm. The presence of detritic pseudosingledomain (PSD)
titanomagnetite, with low titanium content ranging between TM 28 and TM40, has been established. The linear correlation of
SP content with ferrimagnetic susceptibility and with magnetization suggests that ferrimagnetic minerals drive the SP generation.
Finally, it can be concluded that SP magnetic grains, in the Pampean plain, are generated by an inorganic process in adequate
environmental pH and Eh of the soils. 相似文献
202.
Alexander Lorenz Hermann Held Eva Bauer Thomas Schneider von Deimling 《Climate Dynamics》2010,34(5):719-734
Greenland ice-core data containing the 8.2 ka event are utilized by a model-data intercomparison within the Earth system model
of intermediate complexity, CLIMBER-2.3 to investigate their potential for constraining the range of uncertain ocean diffusivity
properties. Within a stochastic version of the model (Bauer et al. in Paleoceanography 19:PA3014, 2004) it has been possible to mimic the pronounced cooling of the 8.2 ka event with relatively good accuracy considering the timing
of the event in comparison to other modelling exercises. When statistically inferring from the 8.2 ka event on diffusivity
the technical difficulty arises to establish the related likelihood numerically per realisation of the uncertain model parameters:
while mainstream uncertainty analyses can assume a quasi-Gaussian shape of likelihood, with weather fluctuating around a long
term mean, the 8.2 ka event as a highly nonlinear effect precludes such an a priori assumption. As a result of this study
the Bayesian Analysis leads to a sharp single-mode likelihood for ocean diffusivity parameters within CLIMBER-2.3. Depending
on the prior distribution this likelihood leads to a reduction of uncertainty in ocean diffusivity parameters (e.g. for flat
prior uncertainty in the vertical ocean diffusivity parameter is reduced by factor 2). These results highlight the potential
of paleo data to constrain uncertain system properties and strongly suggest to make further steps with more complex models
and richer data sets to harvest this potential. 相似文献
203.
The Gross Brukkaros inselberg is a dome structure with a crater-shaped central depression within Precambrian/Cambrian country rocks which was active as a depocenter during the Late Cretaceous. The formation of the structure was due to the intrusion and subsequent intermittent depletion of a shallow magma reservoir. Juvenile material has not been recognized hitherto. This is the first account of juvenile lapilli from within the epiclastic fill of the caldera structure. The lapilli are calciocarbonatites and magnesiocarbonatites in composition, but are characteristically low in elements such as P, Nb, Ba and Sr, otherwise typical of carbonatites. This signature, however, is also characteristic of carbonatites from surrounding volcanic centers and necks. The Brukkaros sediments suffered strong metasomatic-hydrothermal alteration, which introduced in a first stage fluids rich in Fe, Ti, Na, Nb, V, K (Ca?, CO2?), and in a second stage the Brukkaros sediments were silicified on a large scale and locally enriched in P, Th and Cr. Si is derived from desilication of the wall rocks (basement?, Nama sediments) of the magma reservoir. Cr was probably mobilized during alteration of the abundant doleritic detritus within the Brukkaros depocenter. 相似文献
204.
Daniel F. Lorenz 《Natural Hazards》2013,67(1):7-24
The paper presents contributions to the widespread resilience paradigm from a social science perspective. Certain aspects of social systems, especially their symbolic dimension of meaning, need to be taken into account in the endeavor to research coupled social–ecological systems. Due to the symbolic dimension, disasters are defined as the failure of future expectations, and social resilience is defined as the social system property of avoiding or withstanding disasters. In relation to this, three capacities of social systems (adaptive, coping, and participative) that constitute resilience are presented. The adaptive capacity is the property of a system in which structures are modified to prevent future disasters, whereas the coping capacity is the system’s property of coping with calamitous processes that occurred in the past. The participative capacity is a measure of the system’s ability to change its own structures with regard to interventions by other systems, decreasing the system’s resilience. The concept of resilience provides important epistemological and political insights and can help overcome an orientation tied together with the concept of vulnerability that blocks social capacities for the mitigation of disasters. 相似文献
205.
Bernhard Jenny Tom Patterson Lorenz Hurni 《International journal of geographical information science》2013,27(11):1687-1702
The design of new map projections has up until now required mathematical and cartographic expertise that has limited this activity to a small group of specialists. This article introduces the background mathematics for a software-based method that enables cartographers to easily design new small-scale world map projections. The software is usable even by those without mathematical expertise. A new projection is designed interactively in an iterative process that allows the designer to graphically and numerically assess the graticule, the representation of the continents, and the distortion properties of the new projection. The method has been implemented in Flex Projector, a free and open-source application enabling users to quickly create new map projections and modify existing projections. We also introduce new tools that help evaluate the distortion properties of projections, namely a configurable acceptance index to assess areal and angular distortion, a derived acceptance visualization, and interactive profiles through the distortion space of a projection. To illustrate the proposed method, a new projection, the Cropped Ginzburg VIII projection, is presented. 相似文献
206.
S. Nesslinger H. Drechsel R. Lorenz P. Harmanec P. Mayer M. Wolf 《Astrophysics and Space Science》2006,301(1-4):47-49
A Cosmological model with a viscous fluid in Kaluza-Klein metric is obtained assuming a time-dependent equation of state.
The solution is in fact a generalization of an earlier work by Hajj and Boutros for a perfect fluid. It is also found that
dimensional reduction of the extra space takes place such that the five-dimensional universe naturally evolves into an effective
four-dimensional one. The dynamical behavior of the model is examined and it is also found that with a decrease in extra space
the observable 3D space entropy increases thus accounting for the large value of entropy observable at present. 相似文献
207.
The heavy floods in the Taihu Basin Showed increasing trend in recent years.In this work,a typical area in the northern Taihu Basin was selected for flood rish analysis and potential flood losses assessment.human activities have strong impact on the study area‘s flood situation(as affected by the polders built,deforestation,population increase,urbanization,etc.) and have made water level higher,flood duration shorter,and flood peaks sharper.Five years of different flood return periods[(1970),5(1962),10(1987),20(1954),50(1991)] were used to calculate the potential flood risk area and its losses.The potential flood risk map,economic losses,and flood-impacted population were also calculated.The study‘s main conclusions are:1) Human activities have strongly changed the natural flood situation in the study area,increasing runoff and flooding;2) The flood risk area is closely related with the precipitation center;3) Polder construction has successfully protected land from flood.Shortened the flood duration,and elevated water leel in rivers outside the polders;4) Economic and social development have caused flood losses to increase in recent years. 相似文献
208.
Equipped to deal with uncertainty in climate and impacts predictions: lessons from internal peer review 总被引:1,自引:0,他引:1
209.
Ralph D. Lorenz 《Meteoritics & planetary science》2014,49(6):1139-1140
210.
Geospatial data are now widely available to the general public thanks to geoportals and online mapping platforms. However, creating a map involves more than just combining data layers. Thus we develop cartographic functions for geoportals to support better visual hierarchy in user map mashups. This includes a couple of preparatory steps followed by a smart cartographic background symbolization derived from the original layer style. We evaluate different approaches to background symbolization: greyscale, desaturation, and smart background. The different background symbolization methods are analysed with two concrete map examples and evaluated with a survey. The smart background symbolization developed in this work improves the visual hierarchy of the map mashup by reducing the visual importance of the background layers. 相似文献