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Changes in free symptom attributions in hypochondriasis after cognitive therapy and exposure therapy
(2016)
Background: Cognitive-behavioural therapy can change dysfunctional symptom attributions in patients with hypochondriasis. Past research has used forced-choice answer formats, such as questionnaires, to assess these misattributions; however, with this approach, idiosyncratic attributions cannot be assessed. Free associations are an important complement to existing approaches that assess symptom attributions. Aims: With this study, we contribute to the current literature by using an open-response instrument to investigate changes in freely associated attributions after exposure therapy (ET) and cognitive therapy (CT) compared with a wait list (WL). Method: The current study is a re-examination of a formerly published randomized controlled trial (Weck, Neng, Richtberg, Jakob and Stangier, 2015) that investigated the effectiveness of CT and ET. Seventy-three patients with hypochondriasis were randomly assigned to CT, ET or a WL, and completed a 12-week treatment (or waiting period). Before and after the treatment or waiting period, patients completed an Attribution task in which they had to spontaneously attribute nine common bodily sensations to possible causes in an open-response format. Results: Compared with the WL, both CT and ET reduced the frequency of somatic attributions regarding severe diseases (CT: Hedges's g = 1.12; ET: Hedges's g = 1.03) and increased the frequency of normalizing attributions (CT: Hedges's g = 1.17; ET: Hedges's g = 1.24). Only CT changed the attributions regarding moderate diseases (Hedges's g = 0.69). Changes in somatic attributions regarding mild diseases and psychological attributions were not observed. Conclusions: Both CT and ET are effective for treating freely associated misattributions in patients with hypochondriasis. This study supplements research that used a forced-choice assessment.
The interaction of water with α-alumina (i.e. α-Al2O3) surfaces is important in a variety of applications and a useful model for the interaction of water with environmentally abundant aluminosilicate phases. Despite its significance, studies of water interaction with α-Al2O3 surfaces other than the (0001) are extremely limited. Here we characterize the interaction of water (D2O) with a well defined α-Al2O3(1[1 with combining macron]02) surface in UHV both experimentally, using temperature programmed desorption and surface-specific vibrational spectroscopy, and theoretically, using periodic-slab density functional theory calculations. This combined approach makes it possible to demonstrate that water adsorption occurs only at a single well defined surface site (the so-called 1–4 configuration) and that at this site the barrier between the molecularly and dissociatively adsorbed forms is very low: 0.06 eV. A subset of OD stretch vibrations are parallel to this dissociation coordinate, and thus would be expected to be shifted to low frequencies relative to an uncoupled harmonic oscillator. To quantify this effect we solve the vibrational Schrödinger equation along the dissociation coordinate and find fundamental frequencies red-shifted by more than 1500 cm−1. Within the context of this model, at moderate temperatures, we further find that some fraction of surface deuterons are likely delocalized: dissociatively and molecularly absorbed states are no longer distinguishable.
The Milky Way is only one out of billions of galaxies in the universe. However, it is a special galaxy because it allows to explore the main mechanisms involved in its evolution and formation history by unpicking the system star-by-star. Especially, the chemical fingerprints of its stars provide clues and evidence of past events in the Galaxy’s lifetime. These information help not only to decipher the current structure and building blocks of the Milky Way, but to learn more about the general formation process of galaxies.
In the past decade a multitude of stellar spectroscopic Galactic surveys have scanned millions of stars far beyond the rim of the solar neighbourhood. The obtained spectroscopic information provide unprecedented insights to the chemo-dynamics of the Milky Way. In addition analytic models and numerical simulations of the Milky Way provide necessary descriptions and predictions suited for comparison with observations in order to decode the physical properties that underlie the complex system of the Galaxy.
In the thesis various approaches are taken to connect modern theoretical modelling of galaxy formation and evolution with observations from Galactic stellar surveys. With its focus on the chemo-kinematics of the Galactic disk this work aims to determine new observational constraints on the formation of the Milky Way providing also proper comparisons with two different models. These are the population synthesis model TRILEGAL based on analytical distribution functions, which aims to simulate the number and distribution of stars in the Milky Way and its different components, and a hybrid model (MCM) that combines an N-body simulation of a Milky Way like galaxy in the cosmological framework with a semi-analytic chemical evolution model for the Milky Way. The major observational data sets in use come from two surveys, namely the “Radial Velocity Experiment” (RAVE) and the “Sloan Extension for Galactic Understanding and Exploration” (SEGUE).
In the first approach the chemo-kinematic properties of the thin and thick disk of the Galaxy as traced by a selection of about 20000 SEGUE G-dwarf stars are directly compared to the predictions by the MCM model. As a necessary condition for this, SEGUE's selection function and its survey volume are evaluated in detail to correct the spectroscopic observations for their survey specific selection biases. Also, based on a Bayesian method spectro-photometric distances with uncertainties below 15% are computed for the selection of SEGUE G-dwarfs that are studied up to a distance of 3 kpc from the Sun.
For the second approach two synthetic versions of the SEGUE survey are generated based on the above models. The obtained synthetic stellar catalogues are then used to create mock samples best resembling the compiled sample of observed SEGUE G-dwarfs. Generally, mock samples are not only ideal to compare predictions from various models. They also allow validation of the models' quality and improvement as with this work could be especially achieved for TRILEGAL. While TRILEGAL reproduces the statistical properties of the thin and thick disk as seen in the observations, the MCM model has shown to be more suitable in reproducing many chemo-kinematic correlations as revealed by the SEGUE stars. However, evidence has been found that the MCM model may be missing a stellar component with the properties of the thick disk that the observations clearly show. While the SEGUE stars do indicate a thin-thick dichotomy of the stellar Galactic disk in agreement with other spectroscopic stellar studies, no sign for a distinct metal-poor disk is seen in the MCM model.
Usually stellar spectroscopic surveys are limited to a certain volume around the Sun covering different regions of the Galaxy’s disk. This often prevents to obtain a global view on the chemo-dynamics of the Galactic disk. Hence, a suitable combination of stellar samples from independent surveys is not only useful for the verification of results but it also helps to complete the picture of the Milky Way. Therefore, the thesis closes with a comparison of the SEGUE G-dwarfs and a sample of RAVE giants. The comparison reveals that the chemo-kinematic relations agree in disk regions where the samples of both surveys show a similar number of stars. For those parts of the survey volumes where one of the surveys lacks statistics they beautifully complement each other. This demonstrates that the comparison of theoretical models on the one side, and the combined observational data gathered by multiple surveys on the other side, are key ingredients to understand and disentangle the structure and formation history of the Milky Way.
Exosomes are small membrane vesicles released by different cell types, including hepatocytes, that play important roles in intercellular communication. We have previously demonstrated that hepatocyte-derived exosomes contain the synthetic machinery to form sphingosine-1-phosphate (S1P) in target hepatocytes resulting in proliferation and liver regeneration after ischemia/reperfusion (I/R) injury. We also demonstrated that the chemokine receptors, CXCR1 and CXCR2, regulate liver recovery and regeneration after I/R injury. In the current study, we sought to determine if the regulatory effects of CXCR1 and CXCR2 on liver recovery and regeneration might occur via altered release of hepatocyte exosomes. We found that hepatocyte release of exosomes was dependent upon CXCR1 and CXCR2. CXCR1-deficient hepatocytes produced fewer exosomes, whereas CXCR2-deficient hepatocytes produced more exosomes compared to their wild-type controls. In CXCR2-deficient hepatocytes, there was increased activity of neutral sphingomyelinase (Nsm) and intracellular ceramide. CXCR1-deficient hepatocytes had no alterations in Nsm activity or ceramide production. Interestingly, exosomes from CXCR1-deficient hepatocytes had no effect on hepatocyte proliferation, due to a lack of neutral ceramidase and sphingosine kinase. The data demonstrate that CXCR1 and CXCR2 regulate hepatocyte exosome release. The mechanism utilized by CXCR1 remains elusive, but CXCR2 appears to modulate Nsm activity and resultant production of ceramide to control exosome release. CXCR1 is required for packaging of enzymes into exosomes that mediate their hepatocyte proliferative effect.
Children’s interpretations of sentences containing focus particles do not seem adult-like until school age. This study investigates how German 4-year-old children comprehend sentences with the focus particle ‘nur’ (only) by using different tasks and controlling for the impact of general cognitive abilities on performance measures. Two sentence types with ‘only’ in either pre-subject or pre-object position were presented. Eye gaze data and verbal responses were collected via the visual world paradigm combined with a sentence-picture verification task. While the eye tracking data revealed an adult-like pattern of focus particle processing, the sentence-picture verification replicated previous findings of poor comprehension, especially for ‘only’ in pre-subject position. A second study focused on the impact of general cognitive abilities on the outcomes of the verification task. Working memory was related to children’s performance in both sentence types whereas inhibitory control was selectively related to the number of errors for sentences with ‘only’ in pre-subject position. These results suggest that children at the age of 4 years have the linguistic competence to correctly interpret sentences with focus particles, which–depending on specific task demands–may be masked by immature general cognitive abilities.
The energy sector is both affected by climate change and a key sector for climate protection measures. Energy security is the backbone of our modern society and guarantees the functioning of most critical infrastructure. Thus, decision makers and energy suppliers of different countries should be familiar with the factors that increase or decrease the susceptibility of their electricity sector to climate change. Susceptibility means socioeconomic and structural characteristics of the electricity sector that affect the demand for and supply of electricity under climate change. Moreover, the relevant stakeholders are supposed to know whether the given national energy and climate targets are feasible and what needs to be done in order to meet these targets. In this regard, a focus should be on the residential building sector as it is one of the largest energy consumers and therefore emitters of anthropogenic CO 2 worldwide.
This dissertation addresses the first aspect, namely the susceptibility of the electricity sector, by developing a ranked index which allows for quantitative comparison of the electricity sector susceptibility of 21 European countries based on 14 influencing factors. Such a ranking has not been completed to date. We applied a sensitivity analysis to test the relative effect of each influencing factor on the susceptibility index ranking. We also discuss reasons for the ranking position and thus the susceptibility of selected countries. The second objective, namely the impact of climate change on the energy demand of buildings, is tackled by means of a new model with which the heating and cooling energy demand of residential buildings can be estimated. We exemplarily applied the model to Germany and the Netherlands. It considers projections of future changes in population, climate and the insulation standards of buildings, whereas most of the existing studies only take into account fewer than three different factors that influence the future energy demand of buildings. Furthermore, we developed a comprehensive retrofitting algorithm with which the total residential building stock can be modeled for the first time for each year in the past and future.
The study confirms that there is no correlation between the geographical location of a country and its position in the electricity sector susceptibility ranking. Moreover, we found no pronounced pattern of susceptibility influencing factors between countries that ranked higher or lower in the index. We illustrate that Luxembourg, Greece, Slovakia and Italy are the countries with the highest electricity sector susceptibility. The electricity sectors of Norway, the Czech Republic, Portugal and Denmark were found to be least susceptible to climate change. Knowledge about the most important factors for the poor and good ranking positions of these countries is crucial for finding adequate adaptation measures to reduce the susceptibility of the electricity sector. Therefore, these factors are described within this study.
We show that the heating energy demand of residential buildings will strongly decrease in both Germany and the Netherlands in the future. The analysis for the Netherlands focused on the regional level and a finer temporal resolution which revealed strong variations in the future heating energy demand changes by province and by month. In the German study, we additionally investigated the future cooling energy demand and could demonstrate that it will only slightly increase up to the middle of this century. Thus, increases in the cooling energy demand are not expected to offset reductions in heating energy demand. The main factor for substantial heating energy demand reductions is the retrofitting of buildings. We are the first to show that the given German and Dutch energy and climate targets in the building sector can only be met if the annual retrofitting rates are substantially increased. The current rate of only about 1 % of the total building stock per year is insufficient for reaching a nearly zero-energy demand of all residential buildings by the middle of this century. To reach this target, it would need to be at least tripled. To sum up, this thesis emphasizes that country-specific characteristics are decisive for the electricity sector susceptibility of European countries. It also shows for different scenarios how much energy is needed in the future to heat and cool residential buildings. With this information, existing climate mitigation and adaptation measures can be justified or new actions encouraged.
Climate change increases riverine carbon outgassing, while export to the ocean remains uncertain
(2016)
Any regular interaction of land and river during flooding affects carbon pools within the terrestrial system, riverine carbon and carbon exported from the system. In the Amazon basin carbon fluxes are considerably influenced by annual flooding, during which terrigenous organic material is imported to the river. The Amazon basin therefore represents an excellent example of a tightly coupled terrestrial-riverine system. The processes of generation, conversion and transport of organic carbon in such a coupled terrigenous-riverine system strongly interact and are climate-sensitive, yet their functioning is rarely considered in Earth system models and their response to climate change is still largely unknown. To quantify regional and global carbon budgets and climate change effects on carbon pools and carbon fluxes, it is important to account for the coupling between the land, the river, the ocean and the atmosphere. We developed the RIVerine Carbon Model (RivCM), which is directly coupled to the well-established dynamic vegetation and hydrology model LPJmL, in order to account for this large-scale coupling. We evaluate RivCM with observational data and show that some of the values are reproduced quite well by the model, while we see large deviations for other variables. This is mainly caused by some simplifications we assumed. Our evaluation shows that it is possible to reproduce large-scale carbon transport across a river system but that this involves large uncertainties. Acknowledging these uncertainties, we estimate the potential changes in riverine carbon by applying RivCM for climate forcing from five climate models and three CO2 emission scenarios (Special Report on Emissions Scenarios, SRES). We find that climate change causes a doubling of riverine organic carbon in the southern and western basin while reducing it by 20% in the eastern and northern parts. In contrast, the amount of riverine inorganic carbon shows a 2- to 3-fold increase in the entire basin, independent of the SRES scenario. The export of carbon to the atmosphere increases as well, with an average of about 30 %. In contrast, changes in future export of organic carbon to the Atlantic Ocean depend on the SRES scenario and are projected to either decrease by about 8.9% (SRES A1B) or increase by about 9.1% (SRES A2). Such changes in the terrigenous-riverine system could have local and regional impacts on the carbon budget of the whole Amazon basin and parts of the Atlantic Ocean. Changes in riverine carbon could lead to a shift in the riverine nutrient supply and pH, while changes in the exported carbon to the ocean lead to changes in the supply of organic material that acts as a food source in the Atlantic. On larger scales the increased outgassing of CO2 could turn the Amazon basin from a sink of carbon to a considerable source. Therefore, we propose that the coupling of terrestrial and riverine carbon budgets should be included in subsequent analysis of the future regional carbon budget.
Extreme hydro-meteorological events, such as severe droughts or heavy rainstorms, constitute primary manifestations of climate variability and exert a critical impact on the natural environment and human society. This is particularly true for high-mountain areas, such as the eastern flank of the southern Central Andes of NW Argentina, a region impacted by deep convection processes that form the basis of extreme events, often resulting in floods, a variety of mass movements, and hillslope processes. This region is characterized by pronounced E-W gradients in topography, precipitation, and vegetation cover, spanning low to medium-elevation, humid and densely vegetated areas to high-elevation, arid and sparsely vegetated environments. This strong E-W gradient is mirrored by differences in the efficiency of surface processes, which mobilize and transport large amounts of sediment through the fluvial system, from the steep hillslopes to the intermontane basins and further to the foreland. In a highly sensitive high-mountain environment like this, even small changes in the spatiotemporal distribution, magnitude and rates of extreme events may strongly impact environmental conditions, anthropogenic activity, and the well-being of mountain communities and beyond. However, although the NW Argentine Andes comprise the catchments for the La Plata river that traverses one of the most populated and economically relevant areas of South America, there are only few detailed investigations of climate variability and extreme hydro-meteorological events.
In this thesis, I focus on deciphering the spatiotemporal variability of rainfall and river discharge, with particular emphasis on extreme hydro-meteorological events in the subtropical southern Central Andes of NW Argentina during the past seven decades. I employ various methods to assess and quantify statistically significant trend patterns of rainfall and river discharge, integrating high-quality daily time series from gauging stations (40 rainfall and 8 river discharge stations) with gridded datasets (CPC-uni and TRMM 3B42 V7), for the period between 1940 and 2015. Evidence for a general intensification of the hydrological cycle at intermediate elevations (~ 0.5 – 3 km asl) at the eastern flank of the southern Central Andes is found both from rainfall and river-discharge time-series analysis during the period from 1940 to 2015. This intensification is associated with the increase of the annual total amount of rainfall and the mean annual discharge. However, most pronounced trends are found at high percentiles, i.e. extreme hydro-meteorological events, particularly during the wet season from December to February.An important outcome of my studies is the recognition of a rapid increase in the amount of river discharge during the period between 1971 and 1977, most likely linked to the 1976-77 global climate shift, which is associated with the North Pacific Ocean sea surface temperature variability. Interestingly, after this rapid increase, both rainfall and river discharge decreased at low and intermediate elevations along the eastern flank of the Andes. In contrast, during the same time interval, at high elevations, extensive areas on the arid Puna de Atacama plateau have recorded increasing annual rainfall totals. This has been associated with more intense extreme hydro-meteorological events from 1979 to 2014. This part of the study reveals that low-, intermediate, and high-elevation sectors in the Andes of NW Argentina respond differently to changing climate conditions.
Possible forcing mechanisms of the pronounced hydro-meteorological variability observed in the study area are also investigated. For the period between 1940 and 2015, I analyzed modes of oscillation of river discharge from small to medium drainage basins (102 to 104 km2), located on the eastern flank of the orogen. First, I decomposed the relevant monthly time series using the Hilbert-Huang Transform, which is particularly appropriate for non-stationary time series that result from non-linear natural processes. I observed that in the study region discharge variability can be described by five quasi-periodic oscillatory modes on timescales varying from 1 to ~20 years. Secondly, I tested the link between river-discharge variations and large-scale climate modes of variability, using different climate indices, such as the BEST ENSO (Bivariate El Niño-Southern Oscillation Time-series) index. This analysis reveals that, although most of the variance on the annual timescale is associated with the South American Monsoon System, a relatively large part of river-discharge variability is linked to Pacific Ocean variability (PDO phases) at multi-decadal timescales (~20 years). To a lesser degree, river discharge variability is also linked to the Tropical South Atlantic (TSA) sea surface temperature anomaly at multi-annual timescales (~2-5 years).
Taken together, these findings exemplify the high degree of sensitivity of high-mountain environments with respect to climatic variability and change. This is particularly true for the topographic transitions between the humid, low-moderate elevations and the semi-arid to arid highlands of the southern Central Andes. Even subtle changes in the hydro-meteorological regime of these areas of the mountain belt react with major impacts on erosional hillslope processes and generate mass movements that fundamentally impact the transport capacity of mountain streams. Despite more severe storms in these areas, the fluvial system is characterized by pronounced variability of the stream power on different timescales, leading to cycles of sediment aggradation, the loss of agriculturally used land and severe impacts on infrastructure.
Discourse production is crucial for communicative success and is in the core of aphasia assessment and treatment. Coherence differentiates discourse from a series of utterances/sentences; it is internal unity and connectedness, and, as such, perhaps the most inherent property of discourse. It is unclear whether people with aphasia, who experience various language production difficulties, preserve the ability to produce coherent discourse. A more general question of how coherence is established and represented linguistically has been addressed in the literature, yet remains unanswered. This dissertation presents an investigation of discourse production in aphasia and the linguistic mechanisms of establishing coherence.
Caribbean States organised in CARICOM recently brought forward reparation claims against several European States to compensate slavery and (native) genocides in the Caribbean and even threatened to approach the International Court of Justice. The paper provides for an analysis of the facts behind the CARICOM claim and asks whether the law of state responsibility is able to provide for the demanded compensation. As the intertemporal principle generally prohibits retroactive application of today’s international rules, the paper argues that the complete claim must be based on the law of state responsibility governing in the time of the respective conduct. An inquiry into the history of primary (prohibition of slavery and genocide) as well as secondary rules of State responsibility reveals that both sets of rules were underdeveloped or non-existent at the times of slavery and alleged (native) genocides. Therefore, the author concludes that the CARICOM claim is legally flawed but nevertheless worth the attention as it once again exposes imperial and colonial injustices of the past and their legitimization by historical international law and international/natural lawyers.
Archaeology can be understood as a tool used in the process of identity formation,
contributing to a sense of belonging and unity within a diverse set of communities.
Research was conducted with the intention of analyzing the wide range of perceptions
regarding archaeological sites in the mixed city of Lod, Israel. I explored the impact of
urban cultural heritage on shaping the identity of local Jewish and Arab children, who
were chosen as the youngest active members of society living in the city, and who
participated in the 2013 archaeological excavation season at the Khan al-Hilu. Israel is
an ideal location for such research, due to its nature as simultaneously being the focus
of extensive archaeological excavations as well as being the setting of an intractable conflict. Ancestral attachment to the land serves as a foundation for the collective
identity of both Jews and Arabs. Yet, each community and individual may relate differently
to the surrounding archaeological sites, which is further shaped by their sense of
societal hierarchy and cultural heritage.
This article first outlines different ways of how psycholinguists have dealt with linguistic diversity and illustrates these approaches with three familiar cases from research on language processing, language acquisition, and language disorders. The second part focuses on the role of morphology and morphological variability across languages for psycholinguistic research. The specific phenomena to be examined are to do with stem-formation morphology and inflectional classes; they illustrate how experimental research that is informed by linguistic typology can lead to new insights.
This cumulative dissertation contains four self-contained articles which are related to EU regional policy and its structural funds as the overall research topic. In particular, the thesis addresses the question if EU regional policy interventions can at all be scientifically justified and legitimated on theoretical and empirical grounds from an economics point of view. The first two articles of the thesis (“The EU structural funds as a means to hamper migration” and “Internal migration and EU regional policy transfer payments: a panel data analysis for 28 EU member countries”) enter into one particular aspect of the debate regarding the justification and legitimisation of EU regional policy. They theoretically and empirically analyse as to whether regional policy or the market force of the free flow of labour (migration) in the internal European market is the better instrument to improve and harmonise the living and working conditions of EU citizens. Based on neoclassical market failure theory, the first paper argues that the structural funds of the EU are inhibiting internal migration, which is one of the key measures in achieving convergence among the nations in the single European market. It becomes clear that European regional policy aiming at economic growth and cohesion among the member states cannot be justified and legitimated if the structural funds hamper instead of promote migration. The second paper, however, shows that the empirical evidence on the migration and regional policy nexus is not unambiguous, i.e. different empirical investigations show that EU structural funds hamper and promote EU internal migration. Hence, the question of the scientific justification and legitimisation of EU regional policy cannot be readily and unambiguously answered on empirical grounds. This finding is unsatisfying but is in line with previous theoretical and empirical literature. That is why, I take a step back and reconsider the theoretical beginnings of the thesis, which took for granted neoclassical market failure theory as the starting point for the positive explanation as well as the normative justification and legitimisation of EU regional policy. The third article of the thesis (“EU regional policy: theoretical foundations and policy conclusions revisited”) deals with the theoretical explanation and legitimisation of EU regional policy as well as the policy recommendations given to EU regional policymakers deduced from neoclassical market failure theory. The article elucidates that neoclassical market failure is a normative concept, which justifies and legitimates EU regional policy based on a political and thus subjective goal or value-judgement. It can neither be used, therefore, to give a scientifically positive explanation of the structural funds nor to obtain objective and practically applicable policy instruments. Given this critique of neoclassical market failure theory, the third paper consequently calls into question the widely prevalent explanation and justification of EU regional policy given in static neoclassical equilibrium economics. It argues that an evolutionary non-equilibrium economics perspective on EU regional policy is much more appropriate to provide a realistic understanding of one of the largest policies conducted by the EU. However, this does neither mean that evolutionary economic theory can be unreservedly seen as the panacea to positively explain EU regional policy nor to derive objective policy instruments for EU regional policymakers. This issue is discussed in the fourth article of the thesis (“Market failure vs. system failure as a rationale for economic policy? A critique from an evolutionary perspective”). This article reconsiders the explanation of economic policy from an evolutionary economics perspective. It contrasts the neoclassical equilibrium notions of market and government failure with the dominant evolutionary neo-Schumpeterian and Austrian-Hayekian perceptions. Based on this comparison, the paper criticises the fact that neoclassical failure reasoning still prevails in non-equilibrium evolutionary economics when economic policy issues are examined. This is surprising, since proponents of evolutionary economics usually view their approach as incompatible with its neoclassical counterpart. The paper therefore argues that in order to prevent the otherwise fruitful and more realistic evolutionary approach from undermining its own criticism of neoclassical economics and to create a consistent as well as objective evolutionary policy framework, it is necessary to eliminate the equilibrium spirit. Taken together, the main finding of this thesis is that European regional policy and its structural funds can neither theoretically nor empirically be justified and legitimated from an economics point of view. Moreover, the thesis finds that the prevalent positive and instrumental explanation of EU regional policy given in the literature needs to be reconsidered, because these theories can neither scientifically explain the emergence and development of this policy nor are they appropriate to derive objective and scientific policy instruments for EU regional policymakers.
We prove statistical rates of convergence for kernel-based least squares regression from i.i.d. data using a conjugate gradient algorithm, where regularization against overfitting is obtained by early stopping. This method is related to Kernel Partial Least Squares, a regression method that combines supervised dimensionality reduction with least squares projection. Following the setting introduced in earlier related literature, we study so-called "fast convergence rates" depending on the regularity of the target regression function (measured by a source condition in terms of the kernel integral operator) and on the effective dimensionality of the data mapped into the kernel space. We obtain upper bounds, essentially matching known minimax lower bounds, for the L^2 (prediction) norm as well as for the stronger Hilbert norm, if the true
regression function belongs to the reproducing kernel Hilbert space. If the latter assumption is not fulfilled, we obtain similar convergence rates for appropriate norms, provided additional unlabeled data are available.
Convoluted Brownian motion
(2016)
In this paper we analyse semimartingale properties of a class of Gaussian periodic processes, called convoluted Brownian motions, obtained by convolution between a deterministic function and a Brownian motion. A classical
example in this class is the periodic Ornstein-Uhlenbeck process. We compute their characteristics and show that in general, they are neither
Markovian nor satisfy a time-Markov field property. Nevertheless, by enlargement
of filtration and/or addition of a one-dimensional component, one can in some case recover the Markovianity. We treat exhaustively the case of the bidimensional trigonometric convoluted Brownian motion and the higher-dimensional monomial convoluted Brownian motion.
Water scarcity, adaption on climate change, and risk assessment of droughts and floods are critical topics for science and society these days. Monitoring and modeling of the hydrological cycle are a prerequisite to understand and predict the consequences for weather and agriculture. As soil water storage plays a key role for partitioning of water fluxes between the atmosphere, biosphere, and lithosphere, measurement techniques are required to estimate soil moisture states from small to large scales.
The method of cosmic-ray neutron sensing (CRNS) promises to close the gap between point-scale and remote-sensing observations, as its footprint was reported to be 30 ha. However, the methodology is rather young and requires highly interdisciplinary research to understand and interpret the response of neutrons to soil moisture. In this work, the signal of nine detectors has been systematically compared, and correction approaches have been revised to account for meteorological and geomagnetic variations. Neutron transport simulations have been consulted to precisely characterize the sensitive footprint area, which turned out to be 6--18 ha, highly local, and temporally dynamic. These results have been experimentally confirmed by the significant influence of water bodies and dry roads. Furthermore, mobile measurements on agricultural fields and across different land use types were able to accurately capture the various soil moisture states. It has been further demonstrated that the corresponding spatial and temporal neutron data can be beneficial for mesoscale hydrological modeling. Finally, first tests with a gyrocopter have proven the concept of airborne neutron sensing, where increased footprints are able to overcome local effects.
This dissertation not only bridges the gap between scales of soil moisture measurements. It also establishes a close connection between the two worlds of observers and modelers, and further aims to combine the disciplines of particle physics, geophysics, and soil hydrology to thoroughly explore the potential and limits of the CRNS method.
Coupling of attention and saccades when viewing scenes with central and peripheral degradation
(2016)
Degrading real-world scenes in the central or the peripheral visual field yields a characteristic pattern: Mean saccade amplitudes increase with central and decrease with peripheral degradation. Does this pattern reflect corresponding modulations of selective attention? If so, the observed saccade amplitude pattern should reflect more focused attention in the central region with peripheral degradation and an attentional bias toward the periphery with central degradation. To investigate this hypothesis, we measured the detectability of peripheral (Experiment 1) or central targets (Experiment 2) during scene viewing when low or high spatial frequencies were gaze-contingently filtered in the central or the peripheral visual field. Relative to an unfiltered control condition, peripheral filtering induced a decrease of the detection probability for peripheral but not for central targets (tunnel vision). Central filtering decreased the detectability of central but not of peripheral targets. Additional post hoc analyses are compatible with the interpretation that saccade amplitudes and direction are computed in partial independence. Our experimental results indicate that task-induced modulations of saccade amplitudes reflect attentional modulations.
We study the adsorption–desorption transition of polyelectrolyte chains onto planar, cylindrical and spherical surfaces with arbitrarily high surface charge densities by massive Monte Carlo computer simulations. We examine in detail how the well known scaling relations for the threshold transition—demarcating the adsorbed and desorbed domains of a polyelectrolyte near weakly charged surfaces—are altered for highly charged interfaces. In virtue of high surface potentials and large surface charge densities, the Debye–Hückel approximation is often not feasible and the nonlinear Poisson–Boltzmann approach should be implemented. At low salt conditions, for instance, the electrostatic potential from the nonlinear Poisson–Boltzmann equation is smaller than the Debye–Hückel result, such that the required critical surface charge density for polyelectrolyte adsorption σc increases. The nonlinear relation between the surface charge density and electrostatic potential leads to a sharply increasing critical surface charge density with growing ionic strength, imposing an additional limit to the critical salt concentration above which no polyelectrolyte adsorption occurs at all. We contrast our simulations findings with the known scaling results for weak critical polyelectrolyte adsorption onto oppositely charged surfaces for the three standard geometries. Finally, we discuss some applications of our results for some physical–chemical and biophysical systems.