Publications by authors named "Hans Kirschner"

The ability to calibrate learning according to new information is a fundamental component of an organism's ability to adapt to changing conditions. Yet, the exact neural mechanisms guiding dynamic learning rate adjustments remain unclear. Catecholamines appear to play a critical role in adjusting the degree to which we use new information over time, but individuals vary widely in the manner in which they adjust to changes.

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Background: Treatment of unstable forearm fractures in the metaphyseal-diaphyseal junction (MDJ) zone is still a matter of debate. Major drawbacks of all types of fixations include either invasiveness, technical impracticality, or lack of acceptance by patients. This study reports results after antegrade ESIN (a-ESIN) compared to transepiphyseal intramedullary K-wire (TIK) for unstable MDJ forearm fractures.

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A prominent account of decision-making assumes that information is accumulated until a fixed response threshold is crossed. However, many decisions require weighting of information appropriately against time. Collapsing response thresholds are a mathematically optimal solution to this decision problem.

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Deficits in reward learning are core symptoms across many mental disorders. Recent work suggests that such learning impairments arise by a diminished ability to use reward history to guide behaviour, but the neuro-computational mechanisms through which these impairments emerge remain unclear. Moreover, limited work has taken a transdiagnostic approach to investigate whether the psychological and neural mechanisms that give rise to learning deficits are shared across forms of psychopathology.

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Performance monitoring (PM) is a vital component of adaptive behavior and known to be influenced by motivation. We examined effects of potential gain (PG) and loss avoidance (LA) on neural correlates of PM at different processing stages, using a task with trial-based changes in these motivational contexts. Findings suggest more attention is allocated to the PG context, with higher amplitudes for respective correlates of stimulus and feedback processing.

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Polycyclic aromatic compounds with fused benzene rings offer an extraordinary versatility as next-generation organic semiconducting materials for nanoelectronics and optoelectronics due to their tunable characteristics, including charge-carrier mobility and optical absorption. Nonplanarity can be an additional parameter to customize their electronic and optical properties without changing the aromatic core. In this work, we report a combined experimental and theoretical study in which we directly observe large, geometry-induced modifications in the frontier orbitals of a prototypical dye molecule when adsorbed on an atomically thin dielectric interlayer on a metallic substrate.

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Tracing the modifications of molecules in surface chemical reactions benefits from the possibility to image their orbitals. While delocalized frontier orbitals with π character are imaged routinely with photoemission orbital tomography, they are not always sensitive to local chemical modifications, particularly the making and breaking of bonds at the molecular periphery. For such bonds, σ orbitals would be far more revealing.

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Optimal decision making in complex environments requires dynamic learning from unexpected events. To speed up learning, we should heavily weight information that indicates state-action-outcome contingency changes and ignore uninformative fluctuations in the environment. Often, however, unrelated information is hard to ignore and can potentially bias our learning.

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Purpose: Nonsurgical management has been identified as the treatment of choice for femoral shaft fractures in children below four years of age. For various reasons, the surgical approach has become increasingly popular in recent years. The aim of this study is to report results after vertical skin traction and analyze the benefits of this technique as well as to point out advantages compared with surgery in this age group.

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The feedback-related negativity (FRN) is a well-established electrophysiological correlate of feedback-processing. However, there is still an ongoing debate whether the FRN is driven by negative or positive reward prediction errors (RPE), valence of feedback, or mere surprise. Our study disentangles independent contributions of valence, surprise, and RPE on the feedback-related neuronal signal including the FRN and P3 components using the statistical power of a sample of N = 992 healthy individuals.

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Hexacene, composed of six linearly fused benzene rings, is an organic semiconductor material with superior electronic properties. The fundamental understanding of the electronic and chemical properties is prerequisite to any possible application in devices. We investigate the orientation and interface properties of highly ordered hexacene monolayers on Ag(110) and Cu(110) with X-ray photoemission spectroscopy (XPS), photoemission orbital tomography (POT), X-ray absorption spectroscopy (XAS), low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and density functional theory (DFT).

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Purpose The optimal management of medial humeral epicondyle fractures continues to be debated since decades. This single center study analyzes changes and optimizations of treatment over an observation period of 16 years and reports the results. Materials and Methods Retrospective analysis of all patients treated with a medial humeral epicondyle fracture between 2005 and 2020 at our institution.

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Longer acenes such as heptacene are promising candidates for optoelectronic applications but are unstable in their bulk structure as they tend to dimerize. This makes the growth of well-defined monolayers and films problematic. In this article, we report the successful preparation of a highly oriented monolayer of heptacene on Ag(110) by thermal cycloreversion of diheptacenes.

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We revisit the question of kekulene's aromaticity by focusing on the electronic structure of its frontier orbitals as determined by angle-resolved photoemission spectroscopy. To this end, we have developed a specially designed precursor, 1,4,7(2,7)-triphenanthrenacyclononaphane-2,5,8-triene, which allows us to prepare sufficient quantities of kekulene of high purity directly on a Cu(111) surface, as confirmed by scanning tunneling microscopy. Supported by density functional calculations, we determine the orbital structure of kekulene's highest occupied molecular orbital by photoemission tomography.

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Monitoring for errors and behavioral adjustments after errors are essential for daily life. A question that has not been addressed systematically yet, is whether consciously perceived errors lead to different behavioral adjustments compared to unperceived errors. Our goal was to develop a task that would enable us to study different commonly observed neural correlates of error processing and post-error adjustments in their relation to error awareness and accuracy confidence in a single experiment.

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Self-compassion and its cultivation in psychological interventions are associated with improved mental health and well-being. However, the underlying processes for this are not well understood. We randomly assigned 135 participants to study the effect of two short-term self-compassion exercises on self-reported-state mood and psychophysiological responses compared to three control conditions of negative (rumination), neutral, and positive (excitement) valence.

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Background And Objectives: Intolerance of uncertainty (IU) has been linked to Generalized Anxiety Disorder (GAD), but studies experimentally manipulating uncertainty have mostly failed to find differences between GAD patients and controls, possible due to a lack of distinction between uncertainty and ambiguity. This study therefore investigated reactivity to ambiguity in addition to uncertainty in high worriers (HW) and low worriers (LW). We hypothesized an interpretation bias between the groups during ambiguity tasks, while uncertainty would facilitate threat processing of subsequent aversive stimuli.

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Introduction: Elastic stable intramedullary nailing (ESIN) is the first-choice surgical technique for stabilizing various pediatric diaphyseal and selected metaphyseal fractures of the long bones. This technique has increasingly been applied in fractures of the small bones. Here, we report experiences with ESIN in displaced fractures of the metacarpals in children.

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Background: In children with benign bone defects, various treatment options are recommended. Whether these defects should be curetted, osteosynthetically stabilized and/or filled with allogenic or synthetic bone material is still a matter of controversy.

Methods: The reported study presents preliminary results of five children with benign bone lesions of the lower extremity.

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Various surgical techniques have been described for repair of chest wall defects in Poland syndrome. We describe the case of a 16-year-old boy who underwent autologous rib transposition after sternal osteotomy. Chest wall stabilization was achieved using a combination of K-wires and Vertical Expandable Prosthetic Titanium Rib (Synthes GmbH, Freiburg, Germany).

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Introduction: Thoracoscopic approach for repair of esophageal atresia (EA) and tracheo-esophageal fistula (TEF) has become a standard procedure in many pediatric surgical centers. Thoracoscopic surgery in a newborn is demanding from both the surgeon and the patient. The potential benefits for the newborn are still discussed by neonatologists, pediatric intensive care physicians, and also parents.

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Background: In patients with maljunction of pancreatic and common bile duct (CBD)-defined as a long common pancreaticobiliary channel (LCPC)-a resection of the CBD and a hepaticojejunostomy is recommended. To date, this operation is usually performed through an open approach. In this article, we report on our experience with minimally invasive surgery (MIS) for LCPC in children.

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Purpose: Three-dimensional visualization of solid tumors is possible because of high-resolution computed tomography and magnetic resonance imaging scans. However, additional preoperative information is often desirable in complex malignancies. For the first time, the authors present a model of preoperative 3-dimensional visualization and virtual resections in pediatric solid tumors.

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