Memory-matches evoke human gamma-responses

BACKGROUND: Human brain activity in the gamma frequency range has been shown to be a correlate of numerous cognitive functions like attention, perception and memory access. More specifically, gamma activity has been found to be enhanced when stimuli are stored in or match with short-term memory (STM). We tested the hypothesis that gamma activity is also evoked when stimuli match representations in long-term-memory (LTM). EEG was recorded from 13 subjects performing a choice reaction task. Visual stimuli were either known real-world objects with a memory representation or novel configurations never seen before. RESULTS: All stimuli evoked an early gamma response which was maximal over occipital electrodes. This evoked gamma activity was significantly larger for items that matched memory templates. CONCLUSIONS: Therefore, we argue that gamma activity results from the feedback from memory into perception systems. This assumption seems to be true for STM as well as LTM

Effect of Iron Therapy on Platelet Counts in Patients with Inflammatory Bowel Disease-Associated Anemia

Secondary thrombocytosis is a clinical feature of unknown significance. In inflammatory bowel disease (IBD), thrombocytosis is considered a marker of active disease; however, iron deficiency itself may trigger platelet generation. In this study we tested the effect of iron therapy on platelet counts in patients with IBD-associated anemia.Platelet counts were analyzed before and after iron therapy from four prospective clinical trials. Further, changes in hemoglobin, transferrin saturation, ferritin, C-reactive protein, and leukocyte counts, before and after iron therapy were compared. In a subgroup the effect of erythropoietin treatment was tested. The results were confirmed in a large independent cohort (FERGIcor).A total of 308 patient records were available for the initial analysis. A dose-depended drop in platelet counts (mean 425 G/L to 320 G/L; p<0.001) was found regardless of the type of iron preparation (iron sulphate, iron sucrose, or ferric carboxymaltose). Concomitant erythropoietin therapy as well as parameters of inflammation (leukocyte counts, C-reactive protein) had no effect on the change in platelet counts. This effect of iron therapy on platelets was confirmed in the FERGIcor study cohort (n=448, mean platelet counts before iron therapy: 383 G/L, after: 310 G/L, p<0.001).Iron therapy normalizes elevated platelet counts in patients with IBD-associated anemia. Thus, iron deficiency is an important pathogenetic mechanism of secondary thrombocytosis in IBD

Stratospheric aerosol - Observations, processes, and impact on climate

Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfate matter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes

Theoria cum praxis: Specifying an Approach to Train Heterogeneity-Sensitive Reflective Disposition for Teacher Performance

Um eine heterogenitätssensible Schul- und Unterrichtskultur, die anerkennend auf die spezifischen Anforderungen und Bedürfnisse einer heterogenen Schüler*innenschaft eingeht, zu realisieren, sind Lehrkräfte aufgerufen, sich für diese Kultur zu sensibilisieren und selbstreflexiv mit diesen Ansprüchen umzugehen. In der interdisziplinären Struktur der ersten Phase der Lehrkräftebildung liegen für die Professionalisierung angehender Lehrkräfte besondere Chancen und Risiken zu deren Umsetzung. In den verschiedenen Bezugsdisziplinen werden die Studierenden disziplin- und fachspezifisch auf Anforderungen allgemein (schul-)pädagogischer Fragestellungen sowie die der gewählten Unterrichtsfächer vorbereitet. Um den Prozess der Auseinandersetzung mit den Implikationen einer heterogenitätssensiblen Schul- und Unterrichtskultur zu unterstützen, sind die universitären Lehrkräftebildner*innen aufgefordert, Konzepte zu generieren bzw. (weiter-)zuführen, welche die unterschiedlichen Facetten und Strukturebenen des Lehrkräftehandelns fokussieren und den Studierenden die Gemeinsamkeiten bzw. Grenzen verschiedener Professionalisierungsansätze aufzeigen. Mit dem Leitbild der Reflexiven Handlungsfähigkeit wurde an der Universität X ein Konzept (weiter-)entwickelt, um den Umgang mit und die Thematisierung von Heterogenität – bezogen auf verschiedenen Differenzlinien (z. B. Sprache(n) oder Milieu) – als Querschnittsaufgabe aller lehrkräftebildenden Disziplinen abzubilden. Im Versuch, die Interdisziplinarität der Lehrkräftebildung an der Universität X zu betonen, fließen im Leitbild der Reflexiven Handlungsfähigkeit in erster Line strukturtheoretische und kompetenzorientierte Ansätze ein. Beide Theoriestränge sollen in Beziehung gesetzt und mit Blick auf eine heterogenitätssensible Lehrkräftebildung diskutiert werden. Hierdurch soll eine Grundlage für den späteren Lehrberuf im Sinne des berufsbiografischen Ansatzes gelegt werden. Von diesem Theorieverständnis ausgehend wurden Lernziele für die heterogenitätssensible Lehrkräftebildung entwickelt, die verschiedene Facetten Reflexiver Handlungsfähigkeit aufgreifen. Die Arbeit mit Anwendungsbeispielen soll die Studierenden bei der Ausprägung einer heterogenitätssensiblen Reflexiven Handlungsfähigkeit unterstützen.Nowadays, any group of learners is characterized by a great heterogeneity (e.g., socio-economic background, languages, educational background etc.). Dealing with the diverse resources and needs students bring to class in an appreciative way represents one of the major challenges for (future) teachers. Thus, teacher educators are asked to develop concepts and strategies to prepare future teachers for dealing with diverse learner groups in a sensitive and self-reflective way. While the interdisciplinary structure of university teacher education in Germany can be seen as an obstacle to this aim as it shifts the responsibility to combine and reflect on the separate scientific discourses to the students, it also offers a great opportunity to depict and reflect heterogeneity from different perspectives. With the help of an overarching model called Reflexive Handlungsfähigkeit (reflective disposition for teacher performance (RDTP), teacher educators from the university X developed a concept that tries to integrate multiple theoretical approaches of teacher professionalization (structural theory approach, competence-oriented approach and professional biography approach). Seeing heterogeneity and inclusion as a cross-sectional task, teacher educators from the university X then enhanced the model of reflexive agency and formulated concrete goals and use cases that derive from the theory and relevance of several dimensions of diversity (e.g. languages, gender, (dis)ability, cognitive resources etc.)

Interactions of gamma and theta oscillations in the electroencephalogram (EEG) during memory processes

Human subjects typically keep about 7 +/- 2 items in short-term memory (STM). A theoretical neuronal model has been proposed to explain this phenomenon with physiological parameters of brain oscillations in the gamma and theta frequency range, i.e. roughly 30-80 and 4-8 Hz, respectively. In that model, STM capacity equals the number of gamma cycles (e.g. 25 ms for 40 Hz), which fit into one theta cycle (e.g. 166 ms for 6 Hz). The model is based on two assumptions: 1) theta activity should modulate gamma activity and 2) the theta/gamma ratio should correlate with human STM capacity. The first assumption is supported by electrophysiological data showing that the amplitude of gamma oscillations is modulated by the phase of theta activity. However, so far this has only been demonstrated for intracranial recordings. We analyzed human event-related EEG oscillations recorded in a memory experiment in which 13 subjects perceived known and unknown visual stimuli. The paradigm revealed event-related oscillations in the gamma range, which depended significantly on the phase of simultaneous theta activity. Our data are the first scalp-recorded human EEG recordings revealing a relationship between the gamma amplitude and the phase of theta oscillations, supporting the first assumption of the abovementioned theory. Interestingly, the involved frequencies revealed a 7:1 ratio. However, this ratio does not necessarily determine human STM capacity. Since such a correlation was not explicitly tested in our paradigm, our data is not conclusive about the second assumption. Instead of theta phase modulating gamma amplitude, it is also conceivable that focal gamma activity needs to be downsampled to theta activity, before it can interact with more distant brain regions

Structure–Activity Relationships in Bulk Polymeric and Sol–Gel-Derived Carbon Nitrides during Photocatalytic Hydrogen Production

Photocatalytic hydrogen evolution rates and structural properties as well as charge separation, electron transfer, and stabilization have been analyzed in advanced sol–gel-derived carbon nitrides (SG-CN) pyrolyzed at different temperatures (350–600 °C) and in bulk polymeric carbon nitride reference samples (CN) by XRD, XPS, FTIR, UV–vis, Raman, and photoluminescence as well as by in situ EPR spectroscopy. SG-CN samples show about 20 times higher H₂ production rates than bulk CN. This is due to their porous structure, partial disorder, and high surface area which favor short travel distances and fast trapping of separated electrons on the surface where they are available for reaction with protons. In contrast, most of the excited electrons in bulk polymeric CN return quickly to the valence band upon undesired emission of light, which is responsible for their low catalytic activity