Strongly enhanced shot noise in chains of quantum dots

We study charge transport through a chain of quantum dots. The dots are fully coherent among each other and weakly coupled to metallic electrodes via the dots at the interface, thus modelling a molecular wire. If the non-local Coulomb interactions dominate over the inter-dot hopping we find strongly enhanced shot noise above the sequential tunneling threshold. The current is not enhanced in the region of enhanced noise, thus rendering the noise super-Poissonian. In contrast to earlier work this is achieved even in a fully symmetric system. The origin of this novel behavior lies in a competition of "slow" and "fast" transport channels that are formed due to the differing non-local wave functions and total spin of the states participating in transport. This strong enhancement may allow direct experimental detection of shot noise in a chain of lateral quantum dots.Comment: 4 pages, 2 figures, submitted to PR

A plea for studying qualitative individual differences by default [Invited Commentary]

I see great potential in the approach proposed by Rouder and Haaf. First, using an example from unethical decision making, I demonstrate that considering quantitative individual differences alone can make us overlook important psychological phenomena that are only visible at the individual level. Thus, the study of quantitative individual differences should, by default, be complemented by investigation of qualitative individual differences. Second, having powerful tools to study qualitative individual differences in cognition has great potential to advance personality science. Recently, personality psychologists are increasingly working towards obtaining a better understanding of the processes that underlie the expression of personality in behavior. The toolbox provided by Rouder and Haaf may add to this research in meaningful ways

Critical bursts in filtration

Particle detachment bursts during the flow of suspensions through porous media are a phenomenon that can severely affect the efficiency of deep bed filters. Despite the relevance in several industrial fields, little is known about the statistical properties and the temporal organization of these events. We present experiments of suspensions of deionized water carrying quartz particles pushed with a peristaltic pump through a filter of glass beads measuring simultaneously pressure drop, flux and suspension solid fraction. We find that the burst size distribution scales consistently with a power-law, suggesting that we are in the presence of a novel experimental realization of a self-organized critical system. Temporal correlations are present in the time series, alike in other phenomena as earthquakes or neuronal activity bursts, and also an analog to Omori's law can be shown. The understanding of bursts statistics could provide novel insights in different fields, e.g. in filter and petroleum industries.Comment: 7 pages, 9 figure

Trust from a trait perspective: a theoretical framework and empirical test

Corresponding to the pivotal role of trust for all kinds of social interactions and inter-personal relationships, trust has been the target of abundant research across scientific disci-plines. However, an integration of the huge literature is currently missing – thus hampering a common understanding of trust and a synthesis between the fields. Furthermore, from a psy-chological perspective, there is an insufficient understanding of the (basic) personality traits accounting for individual variation in trust. Therefore, the overall objective of this thesis is to bridge the gap between different lines of trust research and to uncover the dispositional de-terminants of trust. To that end, a behavioral view on trust is adopted, defining trust in terms of a risky choice to depend on another. Based on a broad review of the literature, a theoretical framework is distilled, identifying the situational features and personality characteristics un-derlying trust. Specifically, trust is considered to be a function of (1) attitudes toward risky prospects (risk and loss aversion), (2) trustworthiness expectations, and (3) betrayal sensitivity. These determinants are, in turn, rooted in different traits (i.e., anxiety/fear, trustworthiness, and forgiveness) which can be localized in the space defined by basic personality models. Here, the HEXACO model provides particularly clear-cut hypotheses on the basic traits driv-ing trust, including a unique factor for each of the proposed (specific) trait determinants. Building on this reasoning, the empirical part of this thesis presents first evidence on the link between the HEXACO dimensions and trust. As a starting point, the focus was on the Honesty-Humility factor, representing the unique feature of the HEXACO model compared to more established models of personality (e.g., the Five-Factor Model). In line with the pro-posed theoretical framework, two sets of studies provided support for a social projection path from trait trustworthiness to trustworthiness expectations. Specifically, high levels of Hones-ty-Humility predicted more optimistic trustworthiness expectations and – as necessitated by social projection – were also positively linked to trustworthy behavior. As such, the findings not only identify a trait source of trust, but also clarify the dispositional determinants of trust-worthiness. Overall, the theoretical framework and empirical evidence presented in this thesis suggests the fruitfulness to take a closer look at trust – from a trait perspective

Processes and repercussions of slab detachment

The European Alps are a result of the convergence between the European and the Adriatic plate, where the oceanic part of the European plate subducted beneath the Adriatic plate until continental collision occurred and slowed down subduction. This stalling of subduction then resulted in strong extensional stresses in the subducting slab and ultimately in slab detachment. Based on geological and seismological arguments different slab detachment/lithosphere delamination events have been proposed to have occurred in the last 40 Ma. These delamination events have severe effects on surface processes, such as rapid rock uplift, potentially enhanced magmatic activity and significant changes in erosion/deposition processes. However, the direct link between slab detachment and its surface expression has still not been sufficiently quantified. On the one hand, the processes governing the detachment and in particular its time scale are still incompletely understood while on the other hand quantitative links between the detachment and shallow processes are still missing. Next to the uncertain geometry and configuration of slabs beneath the European Alps, our incomplete understanding of the detachment process is one of the reasons why timing, duration and number of detachment events beneath the European Alps are still debated. Here, I summarize the results of different studies within the framework of MB4D that have addressed these issues from a numerical perspective. I show how numerical modelling has increased our quantitative understanding of the slab detachment process and the physical mechanisms governing its temporal evolution. With the increased computational capabilities, high resolution three-dimensional models of slab detachment have also increasingly become feasible, thus enabling us to study three-dimensional effects such as convergence obliquity and slab curvature to an unprecedented degree. By coupling these models of deep detachment processes with stratigraphic modelling, it has also become possible to create synthetic datasets that can then be compared to observed data. In addition to these more generic models, large-scale models of the European Alps have shown that to properly model the evolution of the European Alps, effects of neighbouring slabs have to be taken into account. Finally, creating present-day models of the Alps has been complicated by the fact that the exact slab configuration and geometry is still debated. Depending on interpretations of seismic tomographies, uplift velocities and overall dynamics may change considerably. This has led to technical developments such as the GeophysicalModelGenerator (https://github.com/JuliaGeodynamics/GeophysicalModelGenerator.jl) and the accompanying graphical user interface GeoDataPicker.jl (https://github.com/JuliaGeodynamics/GeoDataPicker.jl) that are designed to significantly facilitate the process of data interpretation and geodynamic model generation

Some transculturalist aspects in David Maillu's Broken Drum

No Abstract

Diversity and motivations among volunteers in nonprofit youth development programs

Portland, Maine, has a variety of programs that connect volunteers with youth based on particular risk factors. While there are many criteria that affect the outcomes programs yield for youth, the quality and reach of many of these small nonprofit programs is dependent on their volunteer capacity. The goals of this descriptive research project were to identify: nonprofit youth development program volunteer characteristics compared with local populations and volunteers nationally; motivations or benefits such volunteers associate with volunteering; and factors associated with volunteers’ overall satisfaction and longevity

Co-tunneling current and shot noise in quantum dots

We derive general expressions for the current and shot noise, taking into account non-Markovian memory effects. In generalization of previous approaches our theory is valid for arbitrary Coulomb interaction and coupling strength and is applicable to quantum dots and more complex systems like molecules. A diagrammatic expansion up to second-order in the coupling strength, taking into account co-tunneling processes, allows for a study of transport in a regime relevant to many experiments. As an example, we consider a single-level quantum dot, focusing on the Coulomb-blockade regime. We find super-Poissonian shot noise due to spin-flip co-tunneling processes at an energy scale different from the one expected from first-order calculations, with a sensitive dependence on the coupling strength.Comment: 4 pages, three figures, submitted to PR