Synchronization of van der Pol oscillators with delayed coupling

The synchronization of self-sustained oscillators such as the van der Pol oscillator is a model for the adjustment of rhythms of oscillating objects due to their weak interaction and has wide applications in natural and technical processes. That these oscillators adjust their frequency or phase to an external forcing or mutually between several oscillators is a phenomenon which can be used in sound synthesis for various purposes. In this paper we focus on the influence of delays on the synchronization properties of these oscillators. As there is no general theory yet on this topic, we mainly present simulation results, together with some background on the non-delayed case. Finally, the theory is also applied in Neukom’s studies 21.1-21.9

Die Arbeitsbeziehung im Coaching - ein Stiefkind der Forschung

Zusammenfassung: Die vorliegende Studie befasst sich mit der Bedeutung der Arbeitsbeziehung im Coaching. 30 halbstrukturierte Interviews mit Coaching-Verantwortlichen aus Schweizer Großunternehmen werden mittels der qualitativen Inhaltsanalyse untersucht. Die Hälfte der befragten Experten ist der Ansicht, dass eine gute Arbeitsbeziehung der zentrale (Wirk-)Faktor von Coaching ist. Ein Drittel erachtet die funktionierende Arbeitsbeziehung als eine wichtige Voraussetzung für das Gelingen eines Coaching-Prozesses. Die am häufigsten genannten Eigenschaften und Kompetenzen, die ein Coach zur Mitgestaltung der Arbeitsbeziehung haben sollte, sind nach Ansicht der Coaching-Verantwortlichen: gut zuhören können, Empathie, Wertschätzung, Vertrauenswürdigkeit, Interesse und Offenheit. Die Diskussion setzt sich mit der Bedeutung der Befunde für die Coaching-Forschung auseinande

Opto-electronic characterization of third-generation solar cells

We present an overview of opto-electronic characterization techniques for solar cells including light-induced charge extraction by linearly increasing voltage, impedance spectroscopy, transient photovoltage, charge extraction and more. Guidelines for the interpretation of experimental results are derived based on charge drift-diffusion simulations of solar cells with common performance limitations. It is investigated how nonidealities like charge injection barriers, traps and low mobilities among others manifest themselves in each of the studied cell characterization techniques. Moreover, comprehensive parameter extraction for an organic bulk-heterojunction solar cell comprising PCDTBT:PC70BM is demonstrated. The simulations reproduce measured results of 9 different experimental techniques. Parameter correlation is minimized due to the combination of various techniques. Thereby a route to comprehensive and accurate parameter extraction is identified

Die postpartale Hämorrhagie (PPH) : Ihre physischen und psychischen Folgen auf die betroffene Frau und deren optimale Nachbetreuung

Darstellung des Themas: Verschiedene Studien belegen die steigenden Raten an postpartalen Hämorrhagien (PPH). Mit dieser Entwicklung erlangt das Thema zunehmend an Bedeutung. Der massive Blutverlust stellt ein schwerwiegendes Ereignis dar und kann in gravieren-den Fällen tödlich sein. In vielen anderen Fällen kann die PPH zu schwerwiegenden physischen und psychischen Folgen führen. Zu dieser Thematik existieren allerdings nur wenige Studien. Ziel: Ziel dieser Arbeit ist es, die physischen und psychischen Folgen einer PPH auf die betroffenen Frauen detailliert darzustellen und Empfehlungen für eine optimale Nachbetreuung abzugeben. Methode: Zur Beantwortung der Fragestellung wurde anhand festgelegter Keywords auf fünf verschiedenen Datenbanken nach themenrelevanter Literatur gesucht. Mittels definierter Ein-, und Ausschlusskriterien wurden fünf Studien ausgewählt, welche analysiert und kritisch diskutiert wurden. Ergebnisse: Diese Bachelorarbeit zeigt, welche – zum Teil schwerwiegenden – physischen und psychischen Folgen eine PPH haben kann. Zudem konnten konkrete Empfehlungen für die Praxis formuliert werden. Schlussfolgerungen: Bei der Betreuung von Frauen nach einer PPH können Hebammen, im Wissen um die möglichen physischen und psychischen Folgen, durch gezieltes Ergreifen vorsorglicher und therapeutischer Massnahmen einen wertvollen Beitrag zur Gesundheitsförderung und Prävention leisten. Wichtig wären dazu die Entwicklung und Umsetzung von Leitlinien, welche den Umgang mit Frauen nach einer PPH regeln, sowie weitere Forschung zur Thematik

A week-end off: the first extensive number-theoretical computation on the ENIAC

The first extensive number-theoretical computation run on the ENIAC, is reconstructed. The problem, computing the exponent of 2 modulo a prime, was set up on the ENIAC during a week-end in July 1946 by the number-theorist D.H. Lehmer, with help from his wife Emma and John Mauchly. Important aspects of the ENIAC's design are presented-and the reconstruction of the implementation of the problem on the ENIAC is discussed in its salient points

Food Control by Government Laboratories: Innovation, Flexibility, and No Restrictions by Reglementation

Part of the work carried out by the government laboratories is devoted to permanent control of some critical foods and involves well-established and standardized methods. Another part, however, particularly the detection of frauds or poor manufacturing practices, presupposes advanced analytical techniques and flexible politics: an agile sense for hot subjects must be combined with good contacts providing the important information and innovative method development to find ways to obtain the evidence required. As shown for examples, ever new methods and approaches are needed, because the fraud and the negligent worker rapidly adjust to the methods applied for the control – in the end, the analysis may even protect a well arranged fraud. The swindler needs certainty about what the government chemists analyze and what methods they apply, and is, therefore, interested in paralyzing the work of the control, e.g. by requiring that only methods approved by time-consuming procedures are accepted by the court. The control must try to surprise and to create commotion, keeping everyone alert

Pseudo-proxy tests of the analogue method to reconstruct spatially resolved global temperature during the Common Era

This study addresses the possibility of carrying out spatially resolved global reconstructions of annual mean temperature using a worldwide network of proxy records and a method based on the search of analogues. Several variants of the method are evaluated, and their performance is analysed. As a test bed for the reconstruction, the PAGES 2k proxy database (version 1.9.0) is employed as a predictor, the HadCRUT4 dataset is the set of observations used as the predictand and target, and a set of simulations from the PMIP3 simulations are used as a pool to draw analogues and carry out pseudo-proxy experiments (PPEs). The performance of the variants of the analogue method (AM) is evaluated through a series of PPEs in growing complexity, from a perfect-proxy scenario to a realistic one where the pseudo-proxy records are contaminated with noise (white and red) and missing values, mimicking the limitations of actual proxies. Additionally, the method is tested by reconstructing the real observed HadCRUT4 temperature based on the calibration of real proxies. The reconstructed fields reproduce the observed decadal temperature variability. From all the tests, we can conclude that the analogue pool provided by the PMIP3 ensemble is large enough to reconstruct global annual temperatures during the Common Era. Furthermore, the search of analogues based on a metric that minimises the RMSE in real space outperforms other evaluated metrics, including the search of analogues in the range-reduced space expanded by the leading empirical orthogonal functions (EOFs). These results show how the AM is able to spatially extrapolate the information of a network of local proxy records to produce a homogeneous gap-free climate field reconstruction with valuable information in areas barely covered by proxies and make the AM a suitable tool to produce valuable climate field reconstructions for the Common Era

Propofol decreases the axonal excitability in rat primary sensory afferents

AIMS: The aim of this present study was to investigate the changes of peripheral sensory nerve excitability produced by propofol. MAIN METHODS: In a recently described in vitro model of rodent saphenous nerve we used the technique of threshold tracking (QTRAC®) to measure changes of axonal nerve excitability of Aβ-fibres caused by propofol. Concentrations of 10μMol, 100μMol and 1000μMol were tested. Latency, peak response, strength-duration time constant (τSD) and recovery cycle of the sensory neuronal action potential (SNAP) were recorded. KEY FINDINGS: Our results have shown that propofol decreases nerve excitability of rat primary sensory afferents in vitro. Latency increased with increasing concentrations (0μMol: 0.96±0.07ms; 1000μMol 1.10±0.06ms, P<0.01). Also, propofol prolonged the relative refractory period (0μMol: 1.79±1.13ms; 100μMol: 2.53±1.38ms, P<0.01), and reduced superexcitability (0 μMol: -14.0±4.0%; 100μMol: -9.5±5.5%) and subexcitability (0μMol: 7.5±1.2%; 1000μMol: 3.6±1.2) significantly during the recovery cycle (P<0.01). SIGNIFICANCE: Our results have shown that propofol decreases nerve excitability of primary sensory afferents. The technique of threshold tracking revealed that axonal voltage-gated ion channels are significantly affected by propofol and therefore might be at least partially responsible for earlier described analgesic effects