Untangling perceptual memory: hysteresis and adaptation map into separate cortical networks

Perception is an active inferential process in which prior knowledge is combined with sensory input, the result of which determines the contents of awareness. Accordingly, previous experience is known to help the brain “decide” what to perceive. However, a critical aspect that has not been addressed is that previous experience can exert 2 opposing effects on perception: An attractive effect, sensitizing the brain to perceive the same again (hysteresis), or a repulsive effect, making it more likely to perceive something else (adaptation). We used functional magnetic resonance imaging and modeling to elucidate how the brain entertains these 2 opposing processes, and what determines the direction of such experience-dependent perceptual effects. We found that although affecting our perception concurrently, hysteresis and adaptation map into distinct cortical networks: a widespread network of higher-order visual and fronto-parietal areas was involved in perceptual stabilization, while adaptation was confined to early visual areas. This areal and hierarchical segregation may explain how the brain maintains the balance between exploiting redundancies and staying sensitive to new information. We provide a Bayesian model that accounts for the coexistence of hysteresis and adaptation by separating their causes into 2 distinct terms: Hysteresis alters the prior, whereas adaptation changes the sensory evidence (the likelihood function)

Total synthesis of elisabethin A

In den letzen zwanzig Jahren haben sich viele Forschungsgruppen mit Gorgonians (Korallen) aufgrund deren Vielfältigkeit an chemischen Verbindungen beschäftigt. Der natürliche Lebensraum dieser Korallen ist der westindische Ozean. Besondere Aufmerksamkeit erhielten dabei die Gorgonien Octocorallia Pseudopterogorgia Elisabethae, die an verschiedenen Orten in der Karibik vorkommt. Chemische Untersuchungen dieses Tieres zeigten ein breites Spektrum biologisch hochaktiver Terpenoide und Sekundärmetabolite. Ein Beispiel dafür sind einige Pseudopterosine, Diterpenoid-Pentose-Glycoside der Amphilectan Klasse, die eine sehr hohe entzündungshemmende und schmerzmildernde Wirkung besitzen. Die einzigartigen Strukturen und bemerkenswerten biologischen Eigenschaften jener Naturstoffe erweckten auch das Interesse von synthetischen Forschungsgruppen. Dadurch entstanden viele Totalsynthesen von Diterpenen, die aus P. Elisabethae isoliert wurden. Ein bis heute ungelöstes Problem stellt die Totalsynthese von Elisabethin A dar. Viele Ansätze von verschiedenen Forschungsgruppen wurden unternommen um diesen komlexen Naturstoff herzustellen, doch keiner davon war erfolgreich. Diese Masterarbeit beschäftigt sich ebenfalls mit der Totalsynthese von Elisabethin A. Im Gegensatz zu anderen Totalsynthesen wählten wir eine intermolekulare Diels-Alder Reaktion um das Grundgerüst aufzubauen. Weitere Schlüsselschritte in der Synthese sind die Einführung der Seitenkette und der anschließende Fünfringschluss zum gewünschten Elisabethingrundgerüst.In the last twenty years several research groups focused their attention on the chemically rich gorgonians (sea fans, sea whips and sea plumes) found in the reef habitants of the West Indian region. Especially the gorgonian octocoral Pseudopterogorgia elisabethae, collected from several locations throughout the Caribbean region, is of particular interest since chemical investigations have revealed these animals to contain large quantities of highly bioactive secondary terpenoid metabolites. For example some pseudopterosins which are diterpene-pentose-glycosides of the amphilectane class possess high anti-inflammatory and analgesic properties. The unique structure and biological activity from some of these natural products motivated synthetic research groups to establish synthetic approaches. These efforts have led to many reported total synthesis of P. elisabethae diterpenes. A still unsolved challenge is the total synthesis of elisabethin A. Many attempts of several synthetic research groups were reported but none of them were able to establish a total synthesis of this complex molecule. This master thesis deals with the total synthesis of elisabethin A too. In contrast to previous published approaches we focused on an early stage Diels-Alder reaction to generate the decaline system with the quaternary carbon atom. Further key steps are the side chain introduction and the five membered ring closing reaction to the desired elisabethin core

Retrospektive Datenerhebung unter dem Gesichtspunkt sozioökonomischer und psychopharmakologischer Aspekte im Rahmen einer Schizophrenie-Spezialstation

Retrospektive Datenerhebung unter dem Gesichtspunkt sozioökonomischer und psychopharmakologischer Aspekte im Rahmen einer Schizophrenie-Spezialstatio

Von Göttern, Drachen und dergleichen

Die vorliegende Arbeit befasst sich mit dem Roman Tian Long Ba Bu, einem der Hauptwerke des im chinesischen Sprachraum höchst populären und einflussreichen Schriftstellers Jin Yong (Zha Liangyong). Tian Long Ba Bu erschien erstmals Mitte der 1960er-Jahre als Fortsetzungsroman in der (von Jin Yong mitgegründeten) Hong Konger Tageszeitung Ming Pao und ist dem Genre der wuxia-Literatur zuzurechnen. Der Hauptteil der vorliegenden Arbeit besteht in einer Übersetzung des ersten Kapitels von Tian Long Ba Bu und ihrer detaillierten Analyse in Form eines Absatzkommentars. Zwei weitere Kapitel, Kapitel XXXI und XLVIII, werden ebenfalls in vollständiger Übersetzung vorgelegt und jeweils durch eine analytische Einführung und sachliche Erläuterungen ergänzt. Ein Anhang (in englischer Sprache) untersucht die strukturierende Funktion, die dem Phänomen der Verdopplung und Verdreifachung in Tian Long Ba Bu auf unterschiedlichen Ebenen zukommt. Die vorliegende Arbeit löst sich von den Konventionen der im Rahmen der area studies verorteten Chinese Literary Studies, indem sie ihre Aufmerksamkeit weniger auf die politischen oder gesellschaftlichen Umstände der Entstehung des Werks sondern vielmehr auf textuelle Phänomene, auf die interne Strukturierung des Romandiskurses richtet. Insofern kann die Analyse als „strukturalistisch“ bezeichnet werden. Sie arbeitet weitgehend textimmanent und folgt in ihrem Arrangement der von der Linearität des Textes vorgegebenen Ordnung. Durch die Auseinandersetzung mit einigen in der zeitgenössischen Sinologie bisher weitgehend vernachlässigten Fragestellungen erschließt die Arbeit eine Anzahl von – in anderen philologischen Disziplinen längst bewährten – methodischen Ansätzen für die mit China befasste Literaturwissenschaft. Sie gibt Anstoß zu einer weniger durch die Erwartungshaltungen und Muster eines dominierenden sozio-politischen Diskurses als durch die Eigenheiten des individuellen Textes determinierten Auseinandersetzung mit der zeitgenössischen chinesischen Literatur, in der Annahme, dass nur eine solche der thematischen und formalen Vielfalt des Stoffes gerecht werden kann.This dissertation is a study of selected chapters from Tian Long Ba Bu, one of the major novels of Jin Yong (Zha Liangyong), a writer who has continued to enjoy great popularity and influence in the entire Chinese cultural sphere during the past few decades. Tian Long Ba Bu first appeared as a serialized novel in the Hong Kong daily newspaper Ming Pao (co-founded by Jin Yong) in the mid 1960s and is part of the tradition of so-called wuxia-fiction. The main section of this study consists in a translation and analysis of the first chapter of Tian Long Ba Bu, conceived as a detailed paragraph-by- paragraph commentary. Two more chapters, XXXI and XLVIII, are likewise presented in full translation and have each been supplemented with an analytical introduction and factual annotations. An appendix (in English language) further examines the structuring function of the phenomena of doubling and trebling, operative in Tian Long Ba Bu at various levels of the narration. Focusing less on the political or social circumstances of the novel ́s creation but rather on textual phenomena and the internal structuring of the novel ́s narrative discourse, the present study disengages itself from the more common practices in the study of contemporary Chinese literature. It is in this sense that the study is to be considered a structuralist close reading; in its disposition, it adheres to the order provided by the linearity of the text itself. Approaching questions largely neglected in contemporary Chinese Literary Studies so far, this paper opens up a number of methodological approaches which, though long-established in other areas of philology, are relatively novel in the study of Chinese Literature. It proposes a debate of modern Chinese Literature determined less by the expectations and patterns of a dominant socio-political discourse than by the particularities of the individual text, claiming that only such an approach can do justice to the thematic and formal diversity of the material at hand

2Statistically significant dependence of the Xaa-Pro peptide bond conformation on secondary structure and amino acid sequence

BACKGROUND: A reliable prediction of the Xaa-Pro peptide bond conformation would be a useful tool for many protein structure calculation methods. We have analyzed the Protein Data Bank and show that the combined use of sequential and structural information has a predictive value for the assessment of the cis versus trans peptide bond conformation of Xaa-Pro within proteins. For the analysis of the data sets different statistical methods such as the calculation of the Chou-Fasman parameters and occurrence matrices were used. Furthermore we analyzed the relationship between the relative solvent accessibility and the relative occurrence of prolines in the cis and in the trans conformation. RESULTS: One of the main results of the statistical investigations is the ranking of the secondary structure and sequence information with respect to the prediction of the Xaa-Pro peptide bond conformation. We observed a significant impact of secondary structure information on the occurrence of the Xaa-Pro peptide bond conformation, while the sequence information of amino acids neighboring proline is of little predictive value for the conformation of this bond. CONCLUSION: In this work, we present an extensive analysis of the occurrence of the cis and trans proline conformation in proteins. Based on the data set, we derived patterns and rules for a possible prediction of the proline conformation. Upon adoption of the Chou-Fasman parameters, we are able to derive statistically relevant correlations between the secondary structure of amino acid fragments and the Xaa-Pro peptide bond conformation

Expression, purification, and characterization of galactose oxidase of Fusarium sambucinum in E. coli

AbstractA gene encoding a galactose oxidase (GalOx) was isolated from Fusarium sambucinum cultures and overexpressed in Escherichia coli yielding 4.4mg enzyme per L of growth culture with a specific activity of 159Umg−1. By adding a C-terminal His-tag the enzyme could be easily purified with a single affinity chromatography step with high recovery rate (90%). The enzyme showed a single band on SDS–PAGE with an apparent molecular mass of 68.5kDa. The pH optimum for the oxidation of galactose was in the range of pH 6–7.5. Optimum temperature for the enzyme activity was 35°C, with a half-life of 11.2min, 5.3min, and 2.7min for incubation at 40°C, 50°C, and 60°C, respectively. From all tested substrates, the highest relative activity was found for 1-methyl-β-galactopyranoside (226Umg−1) and the highest catalytic efficiency (kcat/Km) for melibiose (2700mM−1s−1). The enzyme was highly specific for molecular oxygen as an electron acceptor, and showed no appreciable activity with a range of alternative acceptors investigated. Different chemicals were tested for their effect on GalOx activity. The activity was significantly reduced by EDTA, NaN3, and KCN

Fully Printed Flexible Ultrasound Transducer for Medical Applications

The fabrication of a fully printed, lead-free, polymer piezoelectric transducer is presented and the characterization of its structural, dielectric, and ferroelectric properties at different processing stages is demonstrated. The performance of poly(vinylidene fluoride-trifluoroethylene) transducers with resonance frequency analyses, acoustic power measurements, and pulse-echo experiments is evaluated. Notably, for the first time for a fully printed transducer, an optimal performance in the medical ultrasound range (<15 MHz) is demonstrated with acoustic power >1 W cm(-2), which is promising for applications in epidermal and wearable electronics. Overall, the findings provide a strong foundation for future research in the area of flexible ultrasound transducers