Detection of single trial power coincidence for the identification of distributed cortical processes in a behavioral context

Poster presentation: The analysis of neuronal processes distributed across multiple cortical areas aims at the identification of interactions between signals recorded at different sites. Such interactions can be described by measuring the stability of phase angles in the case of oscillatory signals or other forms of signal dependencies for less regular signals. Before, however, any form of interaction can be analyzed at a given time and frequency, it is necessary to assess whether all potentially contributing signals are present. We have developed a new statistical procedure for the detection of coincident power in multiple simultaneously recorded analog signals, allowing the classification of events as 'non-accidental co-activation'. This method can effectively operate on single trials, each lasting only for a few seconds. Signals need to be transformed into time-frequency space, e.g. by applying a short-time Fourier transformation using a Gaussian window. The discrete wavelet transform (DWT) is used in order to weight the resulting power patterns according to their frequency. Subsequently, the weighted power patterns are binarized via applying a threshold. At this final stage, significant power coincidence is determined across all subgroups of channel combinations for individual frequencies by selecting the maximum ratio between observed and expected duration of co-activation as test statistic. The null hypothesis that the activity in each channel is independent from the activity in every other channel is simulated by independent, random rotation of the respective activity patterns. We applied this procedure to single trials of multiple simultaneously sampled local field potentials (LFPs) obtained from occipital, parietal, central and precentral areas of three macaque monkeys. Since their task was to use visual cues to perform a precise arm movement, co-activation of numerous cortical sites was expected. In a data set with 17 channels analyzed, up to 13 sites expressed simultaneous power in the range between 5 and 240 Hz. On average, more than 50% of active channels participated at least once in a significant power co-activation pattern (PCP). Because the significance of such PCPs can be evaluated at the level of single trials, we are confident that this procedure is useful to study single trial variability with sufficient accuracy that much of the behavioral variability can be explained by the dynamics of the underlying distributed neuronal processes

Dating and geochemistry of zircon and apatite from rhyolite at the UNESCO geosite Rupnica (Mt. Papuk, northern Croatia) and the relationship to the Sava Zone

The Rupnica geosite, a key locality of the UNESCO-protected Papuk Geopark in northern Croatia, is well-known for an excellent exposure of columnar jointing in volcanic rock. This rock is defined as an albite rhyolite that comprises almost pure albite phenocrysts within a fine-grained matrix composed of microphenocrysts of albite, quartz and devitrified volcanic glass. Primary accessory minerals are clinopyroxene, apatite, zircon and magnetite. Haematite, apatite and anatase were found as inclusions in zircon. The albite rhyolite is characterized by a highly siliceous, peraluminous, oxidized (ferroan), dry, alkali-calcic to alkalic composition, with low CaO, MgO, and MnO contents and high FeOT/(FeOT+MgO) ratios. Normalized trace element contents display positive anomalies of K, Pb, and Zr as well as negative anomalies of Nb, P, Ti, Ba and Eu, together with an enrichment of light rare-earth elements (REE) relative to heavy REE. Zircon from the rhyolite of Rupnica is characterized by ratios of Th/U=1.13 and Zr/Hf=55 and contents of HfO2=1.04 wt. % typical for an early-stage igneous zircon crystallized from a dry high-temperature magma in a deep magma chamber. Apatite REE patterns show enrichment of light REE over heavy REE and a pronounced Eu anomaly, typical for apatite from granitoids formed in an oxidizing environment. The magma is of A-type and was generated at high temperatures at 800–900 °C by partial melting of lower- to mid-crustal rocks. The age of the albite rhyolite of Rupnica is Late Cretaceous at 80.8±1.8 (2σ) Ma, according to U-Pb dating of zircon, coeval with geochemically similar igneous rocks of Mt. Požeška Gora and Mt. Kozara within the Sava Zone

Wer gewinnt durch die geplante Föderalismusreform?

Die Föderalismusreform soll die Zuständigkeiten von Bund und Ländern entflechten und für mehr Transparenz sorgen. Wer sind die Gewinner und wer sind die Verlierer der geplanten Änderung? Margret Wintermantel, Präsidentin der Hochschulrektorenkonferenz, befürchtet, dass die Hochschulen die Verlierer der Föderalismusreform sein könnten: "Würde die im Koalitionsvertrag beabsichtigte Föderalismusreform so umgesetzt, wie derzeit geplant, würde dies Nachteile für die Hochschulen in Deutschland mit sich bringen." Auch Hans-Peter Schneider, Universität Hannover, sieht nicht nur Gewinner, sondern auch Verlierer, meist sogar "in beiderlei Gestalt zugleich". Für ihn sind Vor- und Nachteile der Reform bei der einen oder anderen Seite nicht eindeutig zu verbuchen. Für Peter Struck, SPD-Bundestagsfraktion, dagegen werden die Reformziele - stärkere Kompetenztrennung, Abschaffung der Rahmengesetzgebung, Senkung der Zustimmungsquoten von Bundesgesetzen und Neuordnung der Finanzverantwortung von Bund und Ländern, insbes. gegenüber der EU - mit dem vorliegenden Gesamtpaket weitgehend erreicht, so dass sowohl Bund und Länder als auch die Bürger die Gewinner der Reform sind. Diese Ansicht teilt auch Wolfgang Bosbach, CDU/CSU-Bundestagsfraktion. Für ihn ist die Liste derer, die heute objektiv zu den Gewinnern der Reform zu zählen sind, ebenfalls "durchaus stattlich", während Joachim Wieland, Universität Frankfurt, auch Verlierer identifiziert: "Verlierer der Reform werden in gewissem Umfang die Ministerpräsidenten der Länder und ihre Regierungen sein. Ihnen wird die Bühne Bundesrat nur noch in weniger Fällen als gegenwärtig offen stehen."Föderalismus, Reform, Kompetenz, Staat, Hochschule, Gemeinde, Deutschland

Three-Dimensional Model for the Human Cl−/HCO3− Exchanger, AE1, by Homology to the E. coli ClC Protein

AbstractAE1 mediates electroneutral 1:1 exchange of bicarbonate for chloride across the plasma membrane of erythrocytes and type A cells of the renal collecting duct. No high-resolution structure is available for the AE1 membrane domain, which alone is required for its transport activity. A recent electron microscopy structure of the AE1 membrane domain was proposed to have a similar protein fold to ClC chloride channels. We developed a three-dimensional homology model of the AE1 membrane domain, using the Escherichia coli ClC channel structure as a template. This model agrees well with a long list of biochemically established spatial constraints for AE1. To investigate the AE1 transport mechanism, we created point mutations in regions corresponding to E. coli ClC transport mechanism residues. When expressed in HEK293 cells, several mutants had Cl−/HCO3− exchange rates significantly different from that of wild-type AE1. When further assessed in Xenopus laevis oocytes, there were significant changes in the transport activity of several AE1 point mutants as assessed by changes in pH. None of the mutants, however, added an electrogenic component to AE1 transport activity. This indicates that the AE1 point mutants altered the transport activity of AE1, without changing its electrogenicity and stoichiometry. The homology model successfully identified residues in AE1 that are critical to AE1 transport activity. Thus, we conclude that AE1 has a similar protein fold to ClC chloride channels

Functional assessment of SLC4A11, an integral membrane protein mutated in corneal dystrophies

SLC4A11, a member of the SLC4 family of bicarbonate transporters, is a widely expressed integral membrane protein, abundant in kidney and cornea. Mutations of SLC4A11 cause some cases of the blinding corneal dystrophies, congenital hereditary endothelial dystrophy, and Fuchs endothelial corneal dystrophy. These diseases are marked by fluid accumulation in the corneal stroma, secondary to defective fluid reabsorption by the corneal endothelium. The role of SLC4A11 in these corneal dystrophies is not firmly established, as SLC4A11 function remains unclear. To clarify the normal function(s) of SLC4A11, we characterized the protein following expression in the simple, low-background expression system Xenopus laevis oocytes. Since plant and fungal SLC4A11 orthologs transport borate, we measured cell swelling associated with accumulation of solute borate. The plant water/borate transporter NIP5;1 manifested borate transport, whereas human SLC4A11 did not. SLC4A11 supported osmotically driven water accumulation that was electroneutral and Na⁺ independent. Studies in oocytes and HEK293 cells could not detect Na⁺⁻ coupled HCO3⁻ transport or Cl⁻/HCO3⁻ exchange by SLC4A11. SLC4A11 mediated electroneutral NH3 transport in oocytes. Voltagedependent OH⁻ or H⁺ movement was not measurable in SLC4A11- expressing oocytes, but SLC4A11-expressing HEK293 cells manifested low-level cytosolic acidification at baseline. In mammalian cells, but not oocytes, OH⁻/H⁺ conductance may arise when SLC4A11 activates another protein or itself is activated by another protein. These data argue against a role of human SLC4A11 in bicarbonate or borate transport. This work provides additional support for water and ammonia transport by SLC4A11. When expressed in oocytes, SLC4A11 transported NH3, not NH3/H⁺.Facultad de Ciencias MédicasCentro de Investigaciones Cardiovasculare

Medical ethics in the Anthropocene: how are €100 billion of German physicians' pension funds invested?

[No abstract available

On the audibility of microphone nonlinearities

Verschiedene Generationen von Mikrofonen unterscheiden sich in Art und Ausmaß der in der Mikrofonschaltung auftretenden, nichtlinearen Verzerrungen, die durch sehr hohe Schalldrücke erzeugt werden können. Bestimmten Schaltungstypen, insbesondere Röhrenschaltungen, werden hierbei häufig spezielle klangliche Eigenschaften zugesprochen. Um diese Einschätzungen empirisch zu untersuchen, wurden für sechs Mikrofonschaltungen, wie sie seit 1945 bei Kondensatormikrofonen eingesetzt wurden, die dort auftretenden, nichtlinearen Verzerrungen gemessen und in einem Hörversuch geprüft, ab welchem Eingangspegel diese zu hörbaren Klangveränderungen führen. In einem zweiten Schritt wurden die Attribute ermittelt, die diese Veränderungen beschreiben