1,147 research outputs found
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
Handlungsbedarf in fachmathematischen Veranstaltungen? â Spezielle MaĂnahmen an der UniversitĂ€t Paderborn
Die Ausbildung angehender Mathematiklehrer geht sowohl seitens der Studierenden, als auch der Dozenten mit Unzufriedenheiten einher. In diesem Beitrag werden Beobachtungen bezĂŒglich fachmathematischer Veranstaltungen beschrieben und entsprechende MaĂnahmen vorgestellt. Der Schwerpunkt liegt auf der Erstsemesterveranstaltung âEinfĂŒhrung in mathematisches Denken und Arbeitenâ, die bei gleichbleibendem Inhalt mehrere Semester in jeweils unterschiedlicher methodischer Aufbereitung angeboten wird
Transient gene expression in shoot apical meristems of sugarbeet seedlings after particle bombardment
Sugarbeet apices were used as targets for particle bombardment with a microtargeting device. Before examining gene expression, particle penetration experiments were carried out. Transient GUS expression was detected within the first and second cell layers of the meristem. Dividing cells with GUS activity demonstrated that cells survived the bombardment procedur
Cisplatin-Based Chemotherapy for Pulmonary Metastasized Germ Cell Tumors of the Testis - Be Aware of Acute Respiratory Distress Syndrome
Background: Cisplatin-based combination chemotherapy is regarded as standard of care for patients with advanced germ cell tumors. In patients with lung metastases and a high tumor load, an association between induction chemotherapy and the development of a `tumor-associated' acute respiratory distress syndrome (ARDS) has been hypothesized. Case Report: We report the clinical course of a 19-year-old patient who rapidly developed fatal ARDS during the first cycle of chemotherapy using the PEI regimen (cisplatin, etoposide and ifosfamide) for a metastasized (lung, liver, lymph nodes) germ cell tumor of the testis. Conclusion: Further clinical research in order to better define risk factors for developing ARDS in this patient population as well as novel strategies for the prevention and treatment of ARDS in those patients are necessary
Influence of cryopreservation on the cytosine methlation state of potato genomic DNA
Shoot tips of Solanum tuberosum 'Desiree' were successfully cryopreserved by the DMSO droplet method and stored for almost 7 years, while control material was maintained in vitro for the same period of time. To analyse potential epigenetic changes, the DNA methylation status was assayed by methylation-sensitive amplified polymorphism (MSAP) analysis using restriction endonucleases MspI and HpaII. An amount of 93.6% of the analysed MSAP signals were stable among all cryopreserved and in vitro maintained samples tested, indicating extensive stability of DNA methylation. Only 0.9% of MSAP signals showed results that differed between the two treatments and at the same time matched for all three biological replications within each treatment. These can be seen as indicating directed effects of the two treatments on the DNA methylation. Cryopreserved samples displayed in comparison to in vitro stored samples consistent hypomethylation for 0.6% (3 of 469) of MSAP signals (Table 4, pattern 4) and consistent hypermethylation for 0.2% (1 of 469), respectively. For 5.6% of all MSAP signals, inconsistent results were observed among the three biological replications at least for one of the two treatments. These were interpreted as resulting from stochastic DNA methylation changes in individual samples. As results for two biological replications were identical and different from the result for the third biological replication, the direction of methylation change could be determined in those cases. Cases of stochastic loss of CG methylation in cryopreserved samples were most frequent among them, adding up to 3.4% of MSAP signals. Stochastic loss of CG methylation was also found inmaterial maintained in vitro, only for 0.6% of all MSAP signals. In conclusion, methylation changes occurred in long-term cryopreservation of potato, in a random rather than directed fashion. Hence, cryopreservation and long-term in vitro maintenance both induce limited changes of DNA methylation status. The order of magnitude of methylation changes observed was consistent with other studies, where similar rates of DNA methylation changes have been found
PARTICLE BREAKAGE IN THE CYCLONES OF FLUIDIZED BED SYSTEMS
A breakage model is developed to predict the change in particle size distribution of brittle materials that undergo mechanical stress in gas cyclones. The breakage probability depends on the cyclone inlet gas velocity, solids load, particle size, and a material-specific constant. The model is validated with data from experiments on a laboratory gas cyclone with aluminum oxide and iron oxide. The results are applied to calculate the particle size distribution of a chemical looping combustion process with iron ore as oxygen carrier
Herausforderungen der Klimawandel-Auswirkungen fĂŒr die Trinkwasserversorgung
Im Rahmen einer Literatur und Internetrecherche wurden die Herausforderungen des Klimawandels an die Trinkwasserversorgung auf der Grundlage von Erfahrungsberichten, Expertenmeinungen und Prognosen herausgearbeitet. Weiterhin wurden Trenduntersuchungen am Beispiel der Ruhr durchgefĂŒhrt und die AbhĂ€ngigkeit der WasserqualitĂ€t von den wetterabhĂ€ngigen Parametern WasserfĂŒhrung und Wassertemperatur untersucht. Die Ergebnisse zeigen, dass der Klimawandel in NRW im Vergleich zu anderen Regionen der Welt zwar moderater verlĂ€uft, aber dass es trotzdem bereits Erfahrungen mit den Auswirkungen gibt, die einen Anpassungsbedarf im Bereich der Wasserversorgung deutlich machen. So werden die Grundwasserneubildung und die WasserfĂŒhrung in OberflĂ€chengewĂ€ssern saisonal stĂ€rkeren Schwankungen unterliegen, was sich lokal und temporĂ€r sowohl auf die Gewinnungsanlagen als auch auf die WasserqualitĂ€t negativ auswirken kann. Eine Temperaturerhöhung lĂ€sst VerĂ€nderungen von chemischen und biologischen Prozessen in GewĂ€ssern und Böden erwarten und kann zu niedrigeren Sauerstoffkonzentrationen fĂŒhren. AuĂerdem ist eine GefĂ€hrdung der Trinkwasserhygiene im Verteilungsnetz nicht auszuschlieĂen. Es muss damit gerechnet werden, dass einzelne Aufbereitungsprozesse im Hinblicke auf eine verĂ€nderte Rohwasserbeschaffenheit, stĂ€rkere QualitĂ€tsschwankungen und eine Temperaturerhöhung optimiert oder erweitert werden mĂŒssen. Die kurzfristigen Anpassungsmöglichkeiten im laufenden Betrieb der einzelnen Anlagen an stĂ€rkere QualitĂ€tsschwankungen sollten deshalb kritisch ĂŒberprĂŒft und ggf. verbessert werden. Wesentliche Anpassungsstrategien in der Wasserversorgung sind Trinkwasserverbundsysteme, die StĂ€rkung des Multibarrierensystems und die Flexibilisierung von Aufbereitungsstufen
New ZZ Ceti stars from the LAMOST survey
The spectroscopic sky survey carried out by the Large Sky Area Multi-Object
Fiber Spectroscopic Telescope (LAMOST) provides the largest stellar spectra
library in the world until now. A large number of new DA white dwarfs had been
identified based on the LAMOST spectra. The effective temperature () and surface gravity () of most DA white dwarfs were determined
and published in the catalogs, e.g. Zhao et al. (2013), Rebassa-Mansergas et
al. (2015), Gentile Fusillo et al. (2015) and Guo et al. (2015). We selected ZZ
Ceti candidates from the published catalogs by considering whether their
are situated in the ZZ Ceti instability strip. The follow-up
time-series photometric observations for the candidates were performed in 2015
and 2016. Four stars: LAMOST J004628.31+343319.90, LAMOST J062159.49+252335.9,
LAMOST J010302.46+433756.2 and LAMOST J013033.90+273757.9 are finally confirmed
to be new ZZ Ceti stars. They show dominant peaks with amplitudes rising above
the 99.9% confidence level in the amplitude spectra. As LAMOST
J004628.31+343319.90 has an estimated mass of 0.40 and
LAMOST J013033.90+273757.9 has a mass of 0.45 derived from
their values, these two stars are inferred to be potential helium-core
white dwarfs.Comment: 15 pages, 8 figures, 3 tables, accepted for publication in Ap
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