SELLING SHARES TO RETAIL INVESTORS: AUCTION VS. FIXED PRICE

We analyze the problem of selling shares of a divisible good to a large number of buyers when demand is uncertain. We characterize equilibria of two popular mechanisms, a fixed price mechanism and a uniform price auction, and compare the revenues. While in the auction truthful bidding is a dominant strategy, we find that bidders have an incentive to overstate their demand in the fixed price mechanism. For some parameter values this yields the surprising result that the fixed price mechanism outperforms the auction.IPO, Uniform Price Auction, Open Offer, Proportional Rationing.

Geometrically enhanced closed-loop multi-turn sensor devices that enable reliable magnetic domain wall motion

We experimentally realize a sophisticated structure geometry for reliable magnetic domain wall-based multi-turn-counting sensor devices, which we term closed-loop devices that can sense millions of turns. The concept relies on the reliable propagation of domain walls through a cross-shaped intersection of magnetic conduits, to allow the intertwining of loops of the sensor device. As a key step to reach the necessary reliability of the operation, we develop a combination of tilted wires called the syphon structure at the entrances of the cross. We measure the control and reliability of the domain wall propagation individually for cross-shaped intersections, the syphon geometries and finally combinations of the two for various field configurations (strengths and angles). The various measured syphon geometries yield a dependence of the domain wall propagation on the shape that we explain by the effectively acting transverse and longitudinal external applied magnetic fields. The combination of both elements yields a behaviour that cannot be explained by a simple superposition of the individual different maximum field operation values. We identify as an additional process the nucleation of domain walls in the cross, which then allows us to fully gauge the operational parameters. Finally, we demonstrate that by tuning the central dimensions of the cross and choosing the optimum angle for the syphon structure reliable sensor operation is achieved, which paves the way for disruptive multi-turn sensor devices

Berechnung der seitlichen Ankopplung eines Rechteckhohlleiters an einen Rundhohlleiter

Es wird ein Berechnungsverfahren zur Bestimmung der Streuparameter der seitlichen Ankopplung eines Rechteckhohlleiters an einen Rundhohlleiter vorgestellt. Die Anordnung wird in einen Resonator- und drei Hohlleiterbereiche unterteilt. Mit der Methode nach Kühn [1] lassen sich geeignete Ansätze für die Vektorpotentiale finden. Aus den Randbedingungen für das elektromagnetische Feld ergibt sich mit Hilfe der Orthogonalreihenentwicklung ein unendliches System linearer Gleichungen für die Bestimmung der Streuparameter, das abgebrochen und mit numerischen Verfahren gelöst wird. An zwei Beispielen wird die Richtigkeit des Rechenverfahrens durch den Vergleich der berechneten mit gemessenen Streuparametern belegt. © 1994, Walter de Gruyter. Alle Rechte vorbehalten

Glutamate 1-semialdehyde aminotransferase is connected to GluTR by GluTR-binding protein and contributes to the rate-limiting step of 5-aminolevulinic acid synthesis

Tetrapyrroles play fundamental roles in crucial processes including photosynthesis, respiration, and catalysis. In plants, 5-aminolevulinic acid (ALA) is the common precursor of tetrapyrroles. ALA is synthesized from activated glutamate by the enzymes glutamyl-tRNA reductase (GluTR) and glutamate-1-semialdehyde aminotransferase (GSAAT). ALA synthesis is recognized as the rate-limiting step in this pathway. We aimed to explore the contribution of GSAAT to the control of ALA synthesis and the formation of a protein complex with GluTR. In Arabidopsis thaliana, two genes encode GSAAT isoforms: GSA1 and GSA2. A comparison of two GSA knockout mutants with the wild-type revealed the correlation of reduced GSAAT activity and ALA-synthesizing capacity in leaves with lower chlorophyll content. Growth and green pigmentation were more severely impaired in gsa2 than in gsa1, indicating the predominant role of GSAAT2 in ALA synthesis. Interestingly, GluTR accumulated to higher levels in gsa2 than in the wild-type and was mainly associated with the plastid membrane. We propose that the GSAAT content modulates the amount of soluble GluTR available for ALA synthesis. Several different biochemical approaches revealed the GSAAT–GluTR interaction through the assistance of GluTR-binding protein (GBP). A modeled structure of the tripartite protein complex indicated that GBP mediates the stable association of GluTR and GSAAT for adequate ALA synthesis.Peer Reviewe

Projektbericht: Medienwirkungen in der internationalen Politik: Zusammenhänge zwischen Presse und Außenpolitik am Beispiel der Vertragsverhandlungen mit Polen 1969/70

Untersucht werden soll der oft behauptete, aber kaum empirisch belegte Einfluß von Massenmedien auf außenpolitische Entscheidungen. Die zentralen Fragestellungen sind: Beschleunigen oder verlangsamen die Massenmedien außenpolitische Entscheidungs- und Handlungsprozesse? Können Massenmedien die Gruppe der Entscheidungs- und handlungsrelevanten Außenpolitiker vergrößern oder verkleinern? Modifizieren oder determinieren sie gar die außenpolitischen Entscheidungen und Handlungen? - Die Arbeit skizziert die Operationalisierung der Hypothesen, die Methode, das Kategoriensystem der Inhaltsanalyse sowie die Variablen für die schriftliche Befragung (Außenpolitiker und Journalisten). Abschließend wird über den derzeitigen Stand des Projekts berichtet. (AR

Politische Online-Pluriversen: Aggregatanalyse der Twitter-Kommunikation zur Salzburger Landtagswahl 2013

Methodische Herausforderungen der Twitterforschung betreffen unter anderem den Datenumfang, die Subjektivität der Tweet-Auswahl, die Datenreduktion und das Einbettungsproblem bezüglich ausgegrenzter Kommunikationszusammenhänge. In diesem Aufsatz wird ein Verfahren der Twitter-Aggregatanalyse (TAA) vorgeschlagen, das die Willkür des Vorgehens reduziert, auf kommunikative Einbettungen fokussiert und an den Agenda-Setting-Approach bei der Analyse politischer Online- und Offline-Kommunikation anschlussfähig ist. Die neu entwickelte TAA-Methode kombiniert automatisierte Selektion mit manueller Reduktion und konventioneller Inhaltsanalyse und generiert auf dieser Grundlage Tweet-Aggregate, so genannte Twitter-Universen. Durch die Variation der Selektoren und die standardisierten Transformationen der Twitter-Universen bietet die TAA vielfältige Vergleichsmöglichkeiten im Hinblick auf die Themenprioritäten von Politikern, Journalisten und Laien, die sich im Sinne wechselseitiger Beeinflussung interpretieren lassen. Die Leistungsfähigkeit der TAA und deren Interpretationsrelevanz werden am Beispiel der Salzburger Landtagswahlen 2013 demonstriert. Besonderes Augenmerk gilt der Einbettung der Tweets in Gesprächszusammenhänge sowie der Rolle von Tweets ohne Gesprächsresonanz. Des Weiteren werden Themen und Themenhandlungsweisen mit und ohne Politikerbeteiligung ermittelt, die auf Defizite in der Qualität politischer Online-Kommunikation verweisen.Methodological challenges of Twitter analysis concern amongst others data quantity, subjectivity of tweet selection, data reduction and the issue of embedding data with regard to excluded communication contexts. We suggest a procedure of Twitter aggregate analysis (TAA) which reduces procedure arbitrariness, focuses on communicative embedding and connects with the agenda setting-approach when analyzing political online and offline communications. The newly developed TAA-method combines automated selection with manual reduction and conventional content analysis and on this basis thus generates aggregates of tweets: so-called Twitter-universes. By varying the selectors and the standardized transformations of Twitter universes, TAA offers multiple comparisons with regard to topic priorities of politicians, journalists and non-professionals which can be interpreted in the sense of mutual influence. The performance of TAA and its interpretational relevance are illustrated using the example of the local election in Salzburg, Austria in 2013. Particular emphasis will be on the embedding of tweets in in conversations as well as the tweets’ role without conversational resonance. Also, topics and the treatment of topics in tweets with or without politicians' participation are determined which point to deficits in quality within political online communication

Alzheimer's Disease, Oestrogen and Mitochondria: an Ambiguous Relationship

Hormonal deficit in post-menopausal women has been proposed to be one risk factor in Alzheimer's disease (AD) since two thirds of AD patients are women. However, large treatment trials showed negative effects of long-term treatment with oestrogens in older women. Thus, oestrogen treatment after menopause is still under debate, and several hypotheses trying to explain the failure in outcome are under discussion. Concurrently, it was shown that amyloid-beta (Aβ) peptide, the main constituent of senile plaques, as well as abnormally hyperphosphorylated tau protein, the main component of neurofibrillary tangles, can modulate the level of neurosteroids which notably represent neuroactive steroids synthetized within the nervous system, independently of peripheral endocrine glands. In this review, we summarize the role of neurosteroids especially that of oestrogen in AD and discuss their potentially neuroprotective effects with specific regard to the role of oestrogens on the maintenance and function of mitochondria, important organelles which are highly vulnerable to Aβ- and tau-induced toxicity. We also discuss the role of Aβ-binding alcohol dehydrogenase (ABAD), a mitochondrial enzyme able to bind Aβ peptide thereby modifying mitochondrial function as well as oestradiol levels suggesting possible modes of interaction between the three, and the potential therapeutic implication of inhibiting Aβ-ABAD interactio

QUA³CK - A Machine Learning Development Process

Machine learning and data processing are trending topics at the moment. However, there is still alack of a standard process to support a fast, simple, and effective development of machine learningmodels for academia and industry combined. Processes such as KDD or CRISP-DM are highlyspecialized in data mining and business cases. Therefore, engineers often refer to individualapproaches to solve a machine learning problem. Especially in teaching, the lack of a standardprocess is a challenge. Students typically get a better understanding if a systematic approach tosolve problems is given to them. A challenge when formulating a machine learning developmentprocess is to provide standard actions that work on different use-cases. At the same time, it has tobe simple. Complex processes often lead to the wrong approach.The QUA³CK process was created at the Karlsruhe Institute of Technology to fill the gap inresearch and industry for a machine learning development process. However, the main focus wasto reach engineering students with an easy-to-remember, didactic way to solve machine learningproblems. This five-stage process starts with a machine learning question (Q), a problem thathas to be solved. Understanding the data (U) comes next. Then, the loop between selecting anAlgorithm (A), Adapting the features (A), and Adjusting the hyperparameters (A) is executeduntil the system is ready for Conclude and compare (C). At last, the Knowledge transfer (K) ofthe given solution can be realized as deployment in hardware or as a documentation.This paper describes the process and all individual steps in detail. Besides, we present severaluse-cases of QUA³CK in academia and research projects

Agent-Based Modelling of Social-Ecological Systems: Achievements, Challenges, and a Way Forward

Abstract: Understanding social-ecological systems (SES) is crucial to supporting the sustainable management of resources. Agent-based modelling is a valuable tool to achieve this because it can represent the behaviour and interactions of organisms, human actors and institutions. Agent-based models (ABMs) have therefore already been widely used to study SES. However, ABMs of SES are by their very nature complex. They are therefore di icult to parameterize and analyse, which can limit their usefulness. It is time to critically reflect upon the current state-of-the-art to evaluate to what degree the potential of agent-based modelling for gaining general insights and supporting specific decision-making has already been utilized. We reviewed achievements and challenges by building upon developments in good modelling practice in the field of ecological modelling with its longer history. As a reference, we used the TRACE framework, which encompasses elements of model development, testing and analysis. We firstly reviewed achievements and challenges with regard to the elements of the TRACE framework addressed in reviews and method papers of social-ecological ABMs. Secondly, in a mini-review, we evaluated whether and to what degree the elements of the TRACE framework were addressed in publications on specific ABMs. We identified substantial gaps with regard to ( ) communicating whether the models represented real systems well enough for their intended purpose and ( ) analysing the models in a systematic and transparent way so that model output is not only observed but also understood. To fill these gaps, a joint e ort of the modelling community is needed to foster the advancement and use of strategies such as participatory approaches, standard protocols for communication, sharing of source code, and tools and strategies for model design and analysis. Throughout our analyses, we provide specific recommendations and references for improving the state-of-the-art. We thereby hope to contribute to the establishment of a new advanced culture of agent-based modelling of SES that will allow us to better develop general theory and practical solutions