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Parafoveal Load of Word N+1 Modulates Preprocessing Effectivenessof Word N+2 in Chinese Reading
(2010)
Preview benefits (PBs) from two words to the right of the fixated one (i.e., word N+2)and associated parafoveal-on-foveal effects are critical for proposals of distributed lexical processing during reading. This experiment examined parafoveal processing during reading of Chinese sentences, using a boundary manipulation of N+2-word preview with low- and high-frequency words N+1. The main findings were (a) an identity PB for word N+2 that was (b) primarily observed when word N+1 was of high frequency (i.e., an interaction between frequency of word N+1 and PB for word N+2), and (c) a parafoveal-on-foveal frequency effect of word N+1 for fixation durations on word N. We discuss implications for theories of serial attention shifts and parallel distributed processing of words during reading.
The present study explores the role of the word position-in-text in sentence and paragraph reading. Three eye-movement data sets based on the reading of Dutch and German unrelated sentences reveal a sizeable, replicable increase in reading times over several words in the beginning and the end of sentences. The data from the paragraphbased English-language Dundee corpus replicate the pattern and also indicate that the increase in inspection times is driven by the visual boundaries of the text organized in lines, rather than by syntactic sentence boundaries. We argue that this effect is independent of several established lexical, contextual and oculomotor predictors of eye-movement behavior. We also provide evidence that the effect of word position-intext has two independent components: a start-up effect arguably caused by a strategic oculomotor program of saccade planning over the line of text, and a wrap-up effect originating in cognitive processes of comprehension and semantic integration.
Within our research group Bayesian Risk Solutions we have coined the idea of a Bayesian Risk Management (BRM). It claims (1) a more transparent and diligent data analysis as well as (2)an open-minded incorporation of human expertise in risk management. In this dissertation we formulize a framework for BRM based on the two pillars Hardcore-Bayesianism (HCB) and Softcore-Bayesianism (SCB) providing solutions for the claims above. For data analysis we favor Bayesian statistics with its Markov Chain Monte Carlo (MCMC) simulation algorithm. It provides a full illustration of data-induced uncertainty beyond classical point-estimates. We calibrate twelve different stochastic processes to four years of CO2 price data. Besides, we calculate derived risk measures (ex ante/ post value-at-risks, capital charges, option prices) and compare them to their classical counterparts. When statistics fails because of a lack of reliable data we propose our integrated Bayesian Risk Analysis (iBRA) concept. It is a basic guideline for an expertise-driven quantification of critical risks. We additionally review elicitation techniques and tools supporting experts to express their uncertainty. Unfortunately, Bayesian thinking is often blamed for its arbitrariness. Therefore, we introduce the idea of a Bayesian due diligence judging expert assessments according to their information content and their inter-subjectivity.
Development of techniques for earthquake microzonation studies in different urban environment
(2010)
The proliferation of megacities in many developing countries, and their location in areas where they are exposed to a high risk from large earthquakes, coupled with a lack of preparation, demonstrates the requirement for improved capabilities in hazard assessment, as well as the rapid adjustment and development of land-use planning. In particular, within the context of seismic hazard assessment, the evaluation of local site effects and their influence on the spatial distribution of ground shaking generated by an earthquake plays an important role. It follows that the carrying out of earthquake microzonation studies, which aim at identify areas within the urban environment that are expected to respond in a similar way to a seismic event, are essential to the reliable risk assessment of large urban areas. Considering the rate at which many large towns in developing countries that are prone to large earthquakes are growing, their seismic microzonation has become mandatory. Such activities are challenging and techniques suitable for identifying site effects within such contexts are needed. In this dissertation, I develop techniques for investigating large-scale urban environments that aim at being non-invasive, cost-effective and quickly deployable. These peculiarities allow one to investigate large areas over a relative short time frame, with a spatial sampling resolution sufficient to provide reliable microzonation. Although there is a negative trade-off between the completeness of available information and extent of the investigated area, I attempt to mitigate this limitation by combining two, what I term layers, of information: in the first layer, the site effects at a few calibration points are well constrained by analyzing earthquake data or using other geophysical information (e.g., shear-wave velocity profiles); in the second layer, the site effects over a larger areal coverage are estimated by means of single-station noise measurements. The microzonation is performed in terms of problem-dependent quantities, by considering a proxy suitable to link information from the first layer to the second one. In order to define the microzonation approach proposed in this work, different methods for estimating site effects have been combined and tested in Potenza (Italy), where a considerable amount of data was available. In particular, the horizontal-to-vertical spectral ratio computed for seismic noise recorded at different sites has been used as a proxy to combine the two levels of information together and to create a microzonation map in terms of spectral intensity ratio (SIR). In the next step, I applied this two-layer approach to Istanbul (Turkey) and Bishkek (Kyrgyzstan). A similar hybrid approach, i.e., combining earthquake and noise data, has been used for the microzonation of these two different urban environments. For both cities, after having calibrated the fundamental frequencies of resonance estimated from seismic noise with those obtained by analysing earthquakes (first layer), a fundamental frequency map has been computed using the noise measurements carried out within the town (second layer). By applying this new approach, maps of the fundamental frequency of resonance for Istanbul and Bishkek have been published for the first time. In parallel, a microzonation map in terms of SIR has been incorporated into a risk scenario for the Potenza test site by means of a dedicated regression between spectral intensity (SI) and macroseismic intensity (EMS). The scenario study confirms the importance of site effects within the risk chain. In fact, their introduction into the scenario led to an increase of about 50% in estimates of the number of buildings that would be partially or totally collapsed. Last, but not least, considering that the approach developed and applied in this work is based on measurements of seismic noise, their reliability has been assessed. A theoretical model describing the self-noise curves of different instruments usually adopted in microzonation studies (e.g., those used in Potenza, Istanbul and Bishkek) have been considered and compared with empirical data recorded in Cologne (Germany) and Gubbio (Italy). The results show that, depending on the geological and environmental conditions, the instrumental noise could severely bias the results obtained by recording and analysing ambient noise. Therefore, in this work I also provide some guidelines for measuring seismic noise.
Der Aufsatz befasst sich mit der Frage, was man aus der internationalen Forschung darüber weiß, welcher Unterricht und welches Lehrerverhalten Auswirkungen auf die Lernergebnisse der Schüler/innen hat und welche Möglichkeiten es gibt, solches Verhalten zu verstärken. Berücksichtigt werden nur Forschungsergebnisse, die hohen methodischen Anforderungen genügen, kausale Schlussfolgerungen erlauben und generalisierbar sind. Konsequenzen für die Lehrerbildung werden diskutiert.
Der Aufsatz befasst sich mit der Frage, was man aus der internationalen Forschung darüber weiß, welcher Unterricht und welches Lehrerverhalten Auswirkungen auf die Lernergebnisse der Schüler/innen hat und welche Möglichkeiten es gibt, solches Verhalten zu verstärken. Berücksichtigt werden nur Forschungsergebnisse, die hohen methodischen Anforderungen genügen, kausale Schlussfolgerungen erlauben und generalisierbar sind. Konsequenzen für die Lehrerbildung werden diskutiert.
Indonesia is one of the countries most prone to natural hazards. Complex interaction of several tectonic plates with high relative velocities leads to approximately two earthquakes with magnitude Mw>7 every year, being more than 15% of the events worldwide. Earthquakes with magnitude above 9 happen far more infrequently, but with catastrophic effects. The most severe consequences thereby arise from tsunamis triggered by these subduction-related earthquakes, as the Sumatra-Andaman event in 2004 showed. In order to enable efficient tsunami early warning, which includes the estimation of wave heights and arrival times, it is necessary to combine different types of real-time sensor data with numerical models of earthquake sources and tsunami propagation. This thesis was created as a result of the GITEWS project (German Indonesian Tsunami Early Warning System). It is based on five research papers and manuscripts. Main project-related task was the development of a database containing realistic earthquake scenarios for the Sunda Arc. This database provides initial conditions for tsunami propagation modeling used by the simulation system at the early warning center. An accurate discretization of the subduction geometry, consisting of 25x150 subfaults was constructed based on seismic data. Green’s functions, representing the deformational response to unit dip- and strike slip at the subfaults, were computed using a layered half-space approach. Different scaling relations for earthquake dimensions and slip distribution were implemented. Another project-related task was the further development of the ‘GPS-shield’ concept. It consists of a constellation of near field GPS-receivers, which are shown to be very valuable for tsunami early warning. The major part of this thesis is related to the geophysical interpretation of GPS data. Coseismic surface displacements caused by the 2004 Sumatra earthquake are inverted for slip at the fault. The effect of different Earth layer models is tested, favoring continental structure. The possibility of splay faulting is considered and shown to be a secondary order effect in respect to tsunamigenity for this event. Tsunami models based on source inversions are compared to satellite radar altimetry observations. Postseismic GPS time series are used to test a wide parameter range of uni- and biviscous rheological models of the asthenosphere. Steady-state Maxwell rheology is shown to be incompatible with near-field GPS data, unless large afterslip, amounting to more than 10% of the coseismic moment is assumed. In contrast, transient Burgers rheology is in agreement with data without the need for large aseismic afterslip. Comparison to postseismic geoid observation by the GRACE satellites reveals that even with afterslip, the model implementing Maxwell rheology results in amplitudes being too small, and thus supports a biviscous asthenosphere. A simple approach based on the assumption of quasi-static deformation propagation is introduced and proposed for inversion of coseismic near-field GPS time series. Application of this approach to observations from the 2004 Sumatra event fails to quantitatively reconstruct the rupture propagation, since a priori conditions are not fulfilled in this case. However, synthetic tests reveal the feasibility of such an approach for fast estimation of rupturing properties.
Situated in an active tectonic region, Santiago de Chile, the country´s capital with more than six million inhabitants, faces tremendous earthquake hazard. Macroseismic data for the 1985 Valparaiso and the 2010 Maule events show large variations in the distribution of damage to buildings within short distances indicating strong influence of local sediments and the shape of the sediment-bedrock interface on ground motion. Therefore, a temporary seismic network was installed in the urban area for recording earthquake activity, and a study was carried out aiming to estimate site amplification derived from earthquake data and ambient noise. The analysis of earthquake data shows significant dependence on the local geological structure with regards to amplitude and duration. Moreover, the analysis of noise spectral ratios shows that they can provide a lower bound in amplitude for site amplification and, since no variability in terms of time and amplitude is observed, that it is possible to map the fundamental resonance frequency of the soil for a 26 km x 12 km area in the northern part of the Santiago de Chile basin. By inverting the noise spectral rations, local shear wave velocity profiles could be derived under the constraint of the thickness of the sedimentary cover which had previously been determined by gravimetric measurements. The resulting 3D model was derived by interpolation between the single shear wave velocity profiles and shows locally good agreement with the few existing velocity profile data, but allows the entire area, as well as deeper parts of the basin, to be represented in greater detail. The wealth of available data allowed further to check if any correlation between the shear wave velocity in the uppermost 30 m (vs30) and the slope of topography, a new technique recently proposed by Wald and Allen (2007), exists on a local scale. While one lithology might provide a greater scatter in the velocity values for the investigated area, almost no correlation between topographic gradient and calculated vs30 exists, whereas a better link is found between vs30 and the local geology. When comparing the vs30 distribution with the MSK intensities for the 1985 Valparaiso event it becomes clear that high intensities are found where the expected vs30 values are low and over a thick sedimentary cover. Although this evidence cannot be generalized for all possible earthquakes, it indicates the influence of site effects modifying the ground motion when earthquakes occur well outside of the Santiago basin. Using the attained knowledge on the basin characteristics, simulations of strong ground motion within the Santiago Metropolitan area were carried out by means of the spectral element technique. The simulation of a regional event, which has also been recorded by a dense network installed in the city of Santiago for recording aftershock activity following the 27 February 2010 Maule earthquake, shows that the model is capable to realistically calculate ground motion in terms of amplitude, duration, and frequency and, moreover, that the surface topography and the shape of the sediment bedrock interface strongly modify ground motion in the Santiago basin. An examination on the dependency of ground motion on the hypocenter location for a hypothetical event occurring along the active San Ramón fault, which is crossing the eastern outskirts of the city, shows that the unfavorable interaction between fault rupture, radiation mechanism, and complex geological conditions in the near-field may give rise to large values of peak ground velocity and therefore considerably increase the level of seismic risk for Santiago de Chile.
The Antarctic plays an important role in the global climate system. On the one hand, the Antarctic Ice Sheet is the largest freshwater reservoir on Earth. On the other hand, a major proportion of the global bottom-water formation takes place in Antarctic shelf regions, forcing the global thermohaline circulation. The main goal of this dissertation is to provide new insights into the dynamics and stability of the EAIS during the Quaternary. Additionally, variations in the activity of bottom-water formation and their causes are investigated. The dissertation is a German contribution to the International Polar Year 2007/ 2008 and was funded by the ‘Deutsche Forschungsgesellschaft’ (DFG) within the scope of priority program 1158 ‘Antarctic research with comparative studies in Arctic ice regions’. During RV Polarstern expedition ANT-XXIII/9, glaciomarine sediments were recovered from the Prydz Bay-Kerguelen region. Prydz Bay is a key region for the study of East EAIS dynamics, as 16% of the EAIS are drained through the Lambert Glacier into the bay. Thereby, the glacier transports sediment into Prydz Bay which is then further distributed by calving icebergs or by current transport. The scientific approach of this dissertation is the reconstruction of past glaciomarine environments to infer on the response of the Lambert Glacier-Amery Ice Shelf system to climate shifts during the Quaternary. To characterize the depositional setting, sedimentological methods are used and statistical analyses are applied. Mineralogical and (bio)geochemical methods provide a means to reconstruct sediment provenances and to provide evidence on changes in the primary production in the surface water column. Age-depth models were constructed based on palaeomagnetic and palaeointensity measurements, diatom stratigraphy and radiocarbon dating. Sea-bed surface sediments in the investigation area show distinct variations in terms of their clay minerals and heavy-mineral assemblages. Considerable differences in the mineralogical composition of surface sediments are determined on the continental shelf. Clay minerals as well as heavy minerals provide useful parameters to differentiate between sediments which originated from erosion of crystalline rocks and sediments originating from Permo-Triassic deposits. Consequently, mineralogical parameters can be used to reconstruct the provenance of current-transported and ice-rafted material. The investigated sediment cores cover the time intervals of the last 1.4 Ma (continental slope) and the last 12.8 cal. ka BP (MacRobertson shelf). The sediment deposits were mainly influenced by glacial and oceanographic processes and further by biological activity (continental shelf), meltwater input and possibly gravitational transport. Sediments from the continental slope document two major deglacial events: the first deglaciation is associated with the mid-Pleistocene warming recognized around the Antarctic. In Prydz Bay, the Lambert Glacier-Amery Ice Shelf retreated far to the south and high biogenic productivity commenced or biogenic remains were better preserved due to increased sedimentation rates. Thereafter, stable glacial conditions continued until 400 - 500 ka BP. Calving of icebergs was restricted to the western part of the Lambert Glacier. The deeper bathymetry in this area allows for floating ice shelf even during times of decreased sea-level. Between 400 - 500 ka BP and the last interglacial (marine isotope stage 5) the glacier was more dynamic. During or shortly after the last interglacial the LAIS retreated again due to sea-level rise of 6 - 9 m. Both deglacial events correlate with a reduction in the thickness of ice masses in the Prince Charles Mountains. It indicates that a disintegration of the Amery Ice Shelf possibly led to increased drainage of ice masses from the Prydz Bay hinterland. A new end-member modelling algorithm was successfully applied on sediments from the MacRobertson shelf used to unmix the sand grain size fractions sorted by current activity and ice transport, respectively. Ice retreat on MacRobertson Shelf commenced 12.8 cal. ka BP and ended around 5.5 cal. ka BP. During the Holocene, strong fluctuations of the bottomwater activity were observed, probably related to variations of sea-ice formation in the Cape Darnley polynya. Increased activity of bottom-water flow was reconstructed at transitions from warm to cool conditions, whereas bottom-water activity receded during the mid- Holocene climate optimum. It can be concluded that the Lambert Glacier-Amery Ice Shelf system was relatively stable in terms of climate variations during the Quaternary. In contrast, bottom-water formation due to polynya activity was very sensitive to changes in atmospheric forcing and should gain more attention in future research.