Bearbeitungsmuster von Studierenden im Umgang mit formalen Definitionen im Kontext konstanter Folgen

Im Übergang von der Schule zur Hochschule vollzieht sich insbesondere ein Übergang zur formalen Mathematik. Während in der Schulmathematik die Argumentation anhand von Beispielen, Visualisierungen und intuitivem Denken üblich ist, nutzt die Hochschulmathematik Beweise auf Grundlage von Axiomen und Definitionen (Liebendörfer, 2018). Da Studierenden die Rolle von Definitionen bei mathematischen Argumentationen oftmals nicht bewusst ist, verwenden sie diese häufig nicht dazu (Edwards & Ward, 2008). Stattdessen argumentieren viele anhand von Beispielen oder intuitiven Überlegungen, selbst wenn Aufgaben ohne Definitionen nicht gelöst werden können (Alcock & Simpson, 2002; Holguin, 2016). Viele Studierende haben Schwierigkeiten mit den neuen Arbeitsweisen, fühlen sich vom neuen Diskurs ausgeschlossen und verlieren deutlich an Motivation (Liebendörfer, 2018). In diesem Beitrag berichten wir über eine explorative Studie mit dem Ziel, Schwierigkeiten und Strategien von Studierenden beim formalen Argumentieren zu identifizieren

Proteiniphilum saccharofermentans str. M3/6T isolated from a laboratory biogas reactor is versatile in polysaccharide and oligopeptide utilization as deduced from genome-based metabolic reconstructions

Proteiniphilum saccharofermentans str. M3/6T is a recently described species within the family Porphyromonadaceae (phylum Bacteroidetes), which was isolated from a mesophilic laboratory-scale biogas reactor. The genome of the strain was completely sequenced and manually annotated to reconstruct its metabolic potential regarding biomass degradation and fermentation pathways. The P. saccharofermentans str. M3/6T genome consists of a 4,414,963 bp chromosome featuring an average GC-content of 43.63%. Genome analyses revealed that the strain possesses 3396 protein-coding sequences. Among them are 158 genes assigned to the carbohydrate-active-enzyme families as defined by the CAZy database, including 116 genes encoding glycosyl hydrolases (GHs) involved in pectin, arabinogalactan, hemicellulose (arabinan, xylan, mannan, β-glucans), starch, fructan and chitin degradation. The strain also features several transporter genes, some of which are located in polysaccharide utilization loci (PUL). PUL gene products are involved in glycan binding, transport and utilization at the cell surface. In the genome of strain M3/6T, 64 PUL are present and most of them in association with genes encoding carbohydrate-active enzymes. Accordingly, the strain was predicted to metabolize several sugars yielding carbon dioxide, hydrogen, acetate, formate, propionate and isovalerate as end-products of the fermentation process. Moreover, P. saccharofermentans str. M3/6T encodes extracellular and intracellular proteases and transporters predicted to be involved in protein and oligopeptide degradation. Comparative analyses between P. saccharofermentans str. M3/6T and its closest described relative P. acetatigenes str. DSM 18083T indicate that both strains share a similar metabolism regarding decomposition of complex carbohydrates and fermentation of sugars. © 2018 The Author

In-Vitro MPI-Guided IVOCT Catheter Tracking in Real Time for Motion Artifact Compensation

Purpose: Using 4D magnetic particle imaging (MPI), intravascular optical coherence tomography (IVOCT) catheters are tracked in real time in order to compensate for image artifacts related to relative motion. Our approach demonstrates the feasibility for bimodal IVOCT and MPI in-vitro experiments. Material and Methods: During IVOCT imaging of a stenosis phantom the catheter is tracked using MPI. A 4D trajectory of the catheter tip is determined from the MPI data using center of mass sub-voxel strategies. A custom built IVOCT imaging adapter is used to perform different catheter motion profiles: no motion artifacts, motion artifacts due to catheter bending, and heart beat motion artifacts. Two IVOCT volume reconstruction methods are compared qualitatively and quantitatively using the DICE metric and the known stenosis length. Results: The MPI-tracked trajectory of the IVOCT catheter is validated in multiple repeated measurements calculating the absolute mean error and standard deviation. Both volume reconstruction methods are compared and analyzed whether they are capable of compensating the motion artifacts. The novel approach of MPI-guided catheter tracking corrects motion artifacts leading to a DICE coefficient with a minimum of 86% in comparison to 58% for a standard reconstruction approach. Conclusions: IVOCT catheter tracking with MPI in real time is an auspicious method for radiation free MPI-guided IVOCT interventions. The combination of MPI and IVOCT can help to reduce motion artifacts due to catheter bending and heart beat for optimized IVOCT volume reconstructions.Comment: 19 pages, 11 figure

Fachdidaktisches Design von Begründungsvideos im Projekt studiVEMINTvideos

Im Projekt studiVEMINTvideos werden seit Oktober 2019 mathematische Lernvideos zur Unterstützung von Studierenden beim Übergang in die Hochschule erstellt. Diese ergänzen den vorhandenen E Learning-Kurs studiVEMINT (http://go.upb.de/studivemint), der für das selbstständige Wiederholen der Schulmathematik oder das neue Lernen schulmathematischer Inhalte, die nicht mehr oder nur randständig in der Schule behandelt werden, aber für den Start an der Hochschule wichtig sind, entwickelt wurde. Dabei geht es auch um Aufbereitung der Schulmathematik im Hinblick auf die Verwendung in der Hochschule, was etwas formalere Darstellungen und adäquatere Begründungen als in der Mathematik in der Schule beinhaltet. Der Kurs umfasst 13 Lerneinheiten mit für alle mathematikhaltigen Studiengänge relevanten Inhalten. studiVEMINTvideos ist ein Kooperationsprojekt der Universität Paderborn und der Technischen Hochschule Köln und wird bis September 2022 vom Ministerium für Kultur und Wissenschaft des Landes NRW gefördert. Im vorliegenden Beitrag wird exemplarisch anhand des Videotyps Begründungsvideo die Konzeption der Lernvideos genauer vorgestellt und an einem Beispiel illustriert

Review on Chamber-Specific Differences in Right and Left Heart Reactive Oxygen Species Handling

Reactive oxygen species (ROS) exert signaling character (redox signaling), or damaging character (oxidative stress) on cardiac tissue depending on their concentration and/or reactivity. The steady state of ROS concentration is determined by the interplay between its production (mitochondrial, cytosolic, and sarcolemmal enzymes) and ROS defense enzymes (mitochondria, cytosol). Recent studies suggest that ROS regulation is different in the left and right ventricle of the heart, specifically by a different activity of superoxide dismutase (SOD). Mitochondrial ROS defense seems to be lower in right ventricular tissue compared to left ventricular tissue. In this review we summarize the current evidence for heart chamber specific differences in ROS regulation that may play a major role in an observed inability of the right ventricle to compensate for cardiac stress such as pulmonary hypertension. Based on the current knowledge regimes to increase ROS defense in right ventricular tissue should be in the focus for the development of future therapies concerning right heart failure

The novel oligopeptide utilizing species Anaeropeptidivorans aminofermentans M3/9T, its role in anaerobic digestion and occurrence as deduced from large-scale fragment recruitment analyses

Research on biogas-producing microbial communities aims at elucidation of correlations and dependencies between the anaerobic digestion (AD) process and the corresponding microbiome composition in order to optimize the performance of the process and the biogas output. Previously, Lachnospiraceae species were frequently detected in mesophilic to moderately thermophilic biogas reactors. To analyze adaptive genome features of a representative Lachnospiraceae strain, Anaeropeptidivorans aminofermentans M3/9T was isolated from a mesophilic laboratory-scale biogas plant and its genome was sequenced and analyzed in detail. Strain M3/9T possesses a number of genes encoding enzymes for degradation of proteins, oligo- and dipeptides. Moreover, genes encoding enzymes participating in fermentation of amino acids released from peptide hydrolysis were also identified. Based on further findings obtained from metabolic pathway reconstruction, M3/9T was predicted to participate in acidogenesis within the AD process. To understand the genomic diversity between the biogas isolate M3/9T and closely related Anaerotignum type strains, genome sequence comparisons were performed. M3/9T harbors 1,693 strain-specific genes among others encoding different peptidases, a phosphotransferase system (PTS) for sugar uptake, but also proteins involved in extracellular solute binding and import, sporulation and flagellar biosynthesis. In order to determine the occurrence of M3/9T in other environments, large-scale fragment recruitments with the M3/9T genome as a template and publicly available metagenomes representing different environments was performed. The strain was detected in the intestine of mammals, being most abundant in goat feces, occasionally used as a substrate for biogas production.Peer Reviewe