Migration as Submodular Optimization

Migration presents sweeping societal challenges that have recently attracted significant attention from the scientific community. One of the prominent approaches that have been suggested employs optimization and machine learning to match migrants to localities in a way that maximizes the expected number of migrants who find employment. However, it relies on a strong additivity assumption that, we argue, does not hold in practice, due to competition effects; we propose to enhance the data-driven approach by explicitly optimizing for these effects. Specifically, we cast our problem as the maximization of an approximately submodular function subject to matroid constraints, and prove that the worst-case guarantees given by the classic greedy algorithm extend to this setting. We then present three different models for competition effects, and show that they all give rise to submodular objectives. Finally, we demonstrate via simulations that our approach leads to significant gains across the board.Comment: Simulation code is available at https://github.com/pgoelz/migration

Feedback seeking as an active, goal-oriented behavior – a psychological reframing of energy consumption feedback

In the last decade the upcoming of the new digital metering technology combined with communication and information technologies caused a new wave of research on feedback and energy efficiency. In difference to earlier feedback studies, several field trials with sample sizes of several hundred up to thousands of households have been initiated in the European context in parallel. High expectations have been sowed from reviews on existing feedback research. Rather surprisingly the results in energy savings caused by feedback systems incorporating smart metering technology turned out to drag behind the high expectations. This doctoral thesis intends to line out an existing blind spot within the energy feedback research by highlighting the notion of an active recipient pursuing own goals and develop own strategies what to do with feedback. Findings and modelling from feedback research of organizational and social psychology is transferred to energy feedback research and forms the framework of a series of studies analysing empirical data from two large one-years-trials with feedback based on smart metering technologies. Major attention is given to the general concepts introduced in the theoretical frameworks: 1) Do individuals set goals for feedback use? If they do so, how are they are linked with each other – is there empirical evidence for multiple goal profiles? 2) Are the different goals determining the feedback seeking behavior? 3) Is there any empirical evidence that individuals proactively seek feedback information in a web-based feedback system? Do goals for feedback use have any predictive power for the feedback seeking behavior? 4) What is the effect on consumption, if different feedback seeking behaviours are identified, what conclusions in relation to the theoretical framework can be made

Fluid stability in large scale ORCs using siloxanes: long-term experiences and fluid recycling

The results in this work show the influence of long-term operation on the decomposition of working fluids in eight different power plants (both heat-led and electricity-led) in a range of 900 kWel to 2 MWel. All case study plants are using Octamethyltrisiloxane (MDM) as a working fluid. The case study plants are between six to 12 years old. On one system detailed analyses, including the fluid distribution throughout the cycle, have been conducted. All fluid samples have been analysed via Head Space Gas Chromatography Mass Spectrometry (HS-GC-MS). Besides the siloxane composition, the influence of contaminants such as mineral oil based lubricants (and its components) has been examined. In most cases the original main working fluid has degraded to fractions of siloxanes with a lower boiling point (low-boilers) and fractions with a higher boiling point (high-boilers). As a consequence of the analyses, a new fluid management system has been designed and tested in one case study plant (case study number 8). The measures include fluid separation, cleansing and recycling. Pre-post comparisons of fluid samples have proved the effectiveness of the methods. The results show that the recovery of used working fluid offers an alternative to the purchase of fresh fluid, since operating costs can be significantly reduced. For large facilities the prices for new fluid range from e15 per litre (in 2006) to e22 per litre (in 2013), which is a large reinvestment, especially in the light of filling volumes of 4000 litres to 7000 litres per cycle. With the above mentioned method a price of e8 per litre of recovered MDM can be achieved

Apostrophe’s Double

“Apostrophe’s Double” is part of a larger research project studying the (often subliminal) strategies by which literary language writing controls its readership. Part I of the essay argues that the rhetorical trope “apostrophe” functions as one such interpellative apparatus that partitions our world and splits our practices. The trope’s operational distinction between authorized speakers / readers vs. ‘dummy’ addressees / targets sets in motion a hierarchical and divisive logic that empowers some and disqualifies others. Part II argues that there is a second version (or ‘turn’) of the figure of apostrophe that has been neglected altogether, one in which the ‘target’ responds not by turning to the interpellation but by turning away instead. This turn away is key to the poetics of certain strong women poets. Ingeborg Bachmann’s poem “Anrufung des großen Bären” (“Invocation of the Great Bear”) provides a lucid model of the transition from one to the other. Apostrophe is thus double: one establishes the apparatus, the other deconstructs it. Part III contrasts two radically divergent uses of language corresponding to these turns: Bachmann’s “Frankfurt Lectures” enact the radical change towards which her poem leads us. Jonathan Culler’s seminal article “Apostrophe” exemplifies the relation to language Bachmann frees herself from. Two subject positions emerge in the wake of this double apostrophic, each with its own constraints: one is empowered by the apparatus yet must remain subservient to it. The other reclaims sovereignty as a living being from the apparatus, on the condition of radically unrepresentable

Campylobacter jejuni genes Cj1492c and Cj1507c are involved in host cell adhesion and invasion

Background Campylobacter jejuni (C. jejuni) has been assigned as an important food-borne pathogen for human health but many pathogenicity factors of C. jejuni and human host cell responses related to the infection have not yet been adequately clarified. This study aimed to determine further C. jejuni pathogenicity factors and virulence genes based on a random mutagenesis approach. A transposon mutant library of C. jejuni NCTC 11168 was constructed and the ability of individual mutants to adhere to and invade human intestinal epithelial cells was evaluated compared to the wild type. We identified two mutants of C. jejuni possessing altered phenotypes with transposon insertions in the genes Cj1492c and Cj1507c. Cj1492c is annotated as a two-component sensor and Cj1507c is described as a regulatory protein. However, functions of both mutated genes are not clarified so far. Results In comparison to the wild type, Cj::1492c and Cj::1507c showed around 70–80% relative motility and Cj::1492c had around 3-times enhanced adhesion and invasion rates whereas Cj::1507c had significantly impaired adhesive and invasive capability. Moreover, Cj::1492c had a longer lag phase and slower growth rate while Cj::1507c showed similar growth compared to the wild type. Between 5 and 24 h post infection, more than 60% of the intracellular wild type C. jejuni were eliminated in HT-29/B6 cells, however, significantly fewer mutants were able to survive intracellularly. Nevertheless, no difference in host cell viability and induction of the pro-inflammatory chemokine IL-8 were determined between both mutants and the wild type. Conclusion We conclude that genes regulated by Cj1507c have an impact on efficient adhesion, invasion and intracellular survival of C. jejuni in HT-29/B6 cells. Furthermore, potential signal sensing by Cj1492c seems to lead to limiting attachment and hence internalisation of C. jejuni. However, as the intracellular survival capacities are reduced, we suggest that signal sensing by Cj1492c impacts several processes related to pathogenicity of C. jejuni

E/Valuating new media in language development

This paper addresses the need for a new approach to the educational evaluation of software that falls under the rubric "new media" or "multimedia" as distinct from previous generations of Computer-Assisted Language Learning (CALL) software. The authors argue that present approaches to CALL software evaluation are not appropriate for a new genre of CALL software distinguished by its shared assumptions about language learning and teaching as well as by its technical design. The paper sketches a research-based program called "E/Valuation" that aims to assist language educators to answer questions about the educational effectiveness of recent multimedia language learning software. The authors suggest that such program needs to take into account not only the nature of the new media and its potential to promote language learning in novel ways, but also current professional knowledge about language learning and teaching

An Empirical Analysis of Credibility Assessment in German Asylum Cases

This study analyzes empirically how 236 German court decisions assess the credibility of asylum seekers’ accounts of their persecution. In their reasoning, the courts rely on generally accepted content-based credibility criteria, including consistency, level of detail, and timeliness of the claim. But they also rely on conduct-based criteria, which have been resoundingly discredited in the relevant scientific literature. Too rarely, the courts considered confounding factors such as cultural distance or interpreter mistakes. They need to be more aware of their duty to confront applicants with negative credibility criteria. Article 4 (5) Qualification Directive played no role whatsoever in the sample analyzed in this study, which can be explained by specifics of German asylum law. The human judgment that is required in the balancing of credibility criteria and confounding factors is problematic for its subjectivity but unavoidable. Attempts at replacing this human credibility assessment with seemingly objective technical means have led to arbitrary decisions and encroached gravely on applicants’ human rights. While the credibility assessment procedure employed in German courts is far from flawless, it can produce convincing decisions. It should be further refined and provided with safeguards to arrive at decisions that are as rational and objective as possible

Multiple Hypothesis Testing Framework for Spatial Signals

The problem of identifying regions of spatially interesting, different or adversarial behavior is inherent to many practical applications involving distributed multisensor systems. In this work, we develop a general framework stemming from multiple hypothesis testing to identify such regions. A discrete spatial grid is assumed for the monitored environment. The spatial grid points associated with different hypotheses are identified while controlling the false discovery rate at a pre-specified level. Measurements are acquired using a large-scale sensor network. We propose a novel, data-driven method to estimate local false discovery rates based on the spectral method of moments. Our method is agnostic to specific spatial propagation models of the underlying physical phenomenon. It relies on a broadly applicable density model for local summary statistics. In between sensors, locations are assigned to regions associated with different hypotheses based on interpolated local false discovery rates. The benefits of our method are illustrated by applications to spatially propagating radio waves.Comment: Submitted to IEEE Transactions on Signal and Information Processing over Network