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IDF-Report. Volume 42, 2011
(2011)
IDF-Report 18 (2009)
(2009)
The true revolution in the age of digital neuroanatomy is the ability to extensively quantify anatomical structures and thus investigate structure-function relationships in great detail. Large-scale projects were recently launched with the aim of providing infrastructure for brain simulations. These projects will increase the need for a precise understanding of brain structure, e.g., through statistical analysis and models.
From articles in this Research Topic, we identify three main themes that clearly illustrate how new quantitative approaches are helping advance our understanding of neural structure and function. First, new approaches to reconstruct neurons and circuits from empirical data are aiding neuroanatomical mapping. Second, methods are introduced to improve understanding of the underlying principles of organization. Third, by combining existing knowledge from lower levels of organization, models can be used to make testable predictions about a higher-level organization where knowledge is absent or poor. This latter approach is useful for examining statistical properties of specific network connectivity when current experimental methods have not yet been able to fully reconstruct whole circuits of more than a few hundred neurons.
The 14 known localities of Coenagrion armatum in Ukraine are listed and the 27 dragonfly species recorded are presented. An expedition devoted to revisit 10 of them in spring 2007 did not result in a confirmation at any of them. Here, all localities are described in detail and possible reasons for the absence of the species are discussed. These include habitat alterations because of anthropogenic impact, such as agricultural activity, as well as decreasing competitiveness against Mediterranean species that spread in response to altered climatic conditions. Proposed measures of conservation of C. armatum in Ukraine include a) the inclusion into the Red Data Book of Ukraine under category I (Endangered) and b) additional studies, monitoring and habitat conservation.
Twenty-eight Odonata species were recorded in the Poliskyi Nature Reserve (Zhytomyr oblast’, North Ukraine) in 2006 and 2007, 18 of which were reported for the first time from this location. This included such rare species as Somatochlora arctica (second record in the Ukraine, first record for 100 years), Leucorrhinia dubia, Leucorrhinia rubicunda and Leucorrhinia albifrons. A breeding site and a dense population of Nehalennia speciosa were found in a bog near the river. Zholobnytsya. The record of Orthetrum coerulescens is the northernmost in Ukraine.
Contents : KLAUS REINHARDT : Aspects of the dragonfly fauna of eastern Kazakstan, MARTIN SCHORR : Bilder aus dem Leben des Odonatologen Dr. Erich Schmidt (1890 - 1969), Rechenschaftsbericht über das Geschäftsjahr 1999
In common with several other autoimmune diseases, autoimmune Addison's disease (AAD) is thought to be caused by a combination of deleterious susceptibility polymorphisms in several genes, together with undefined environmental factors and stochastic events. To date, the strongest genomic association with AAD has been with alleles at the HLA locus, DR3-DQ2 and DR4. The contribution of other genetic variants has been inconsistent. We have studied the association of 16 single-nucleotide polymorphisms (SNPs) within the CD28-CTLA-4-ICOS genomic locus, in a cohort comprising 691 AAD patients of Norwegian and UK origin with matched controls. We have also performed a meta-analysis including 1002 patients from European countries. The G-allele of SNP rs231775 in CTLA-4 is associated with AAD in Norwegian patients (odds ratio (OR)=1.35 (confidence interval (CI) 1.10-1.66), P=0.004), but not in UK patients. The same allele is associated with AAD in the total European population (OR=1.37 (CI 1.13-1.66), P=0.002). A three-marker haplotype, comprising PROMOTER_1661, rs231726 and rs1896286 was found to be associated with AAD in the Norwegian cohort only (OR 2.43 (CI 1.68-3.51), P=0.00013). This study points to the CTLA-4 gene as a susceptibility locus for the development of AAD, and refines its mapping within the wider genomic locus.
A 79 year old female patient was admitted to our emergency department with a fracture of the right medial femoral neck six days after a fall on her right side and a cemented hemiprosthesis was implanted. Five days later, she developed a hemorrhagic shock and was diagnosed with a delayed splenic rupture and the spleen was resected. Histopathological examination showed a delayed rupture of an otherwise normal spleen without signs of an underlying pathology. The outcome was fatal: In the postoperative course she developed pneumonia, three weeks later she succumbed due to multiple organ failure.
Even careful reevaluation of the case did not provide any clues to expect an injury of the spleen according to trauma mechanism.
This case shows that delayed splenic rupture of a normal spleen may occur even after a low energy trauma. Injury of the spleen should therefore always be considered, even with an uncharacteristic anamnesis. Physical examination after trauma should therefore always include a careful clinical evaluation. The clinical threshold for a FAST examination should be low.
The coincidence of a femoral neck fracture and a splenic rupture after a low energy trauma has not been reported before.
Background The endogenous amino acid homoarginine predicts mortality in cerebro‐ and cardiovascular disease. The objective was to explore whether homoarginine is associated with atrial fibrillation (AF) and outcome in patients with acute chest pain.
Methods and Results One thousand six hundred forty‐nine patients with acute chest pain were consecutively enrolled in this study, of whom 589 were diagnosed acute coronary syndrome (ACS). On admission, plasma concentrations of homoarginine as well as brain natriuretic peptide (BNP), and high‐sensitivity assayed troponin I (hsTnI) were determined along with electrocardiography (ECG) variables. During a median follow‐up of 183 days, 60 major adverse cardiovascular events (MACEs; 3.8%), including all‐cause death, myocardial infarction, or stroke, were registered in the overall study population and 43 MACEs (7.5%) in the ACS subgroup. Adjusted multivariable Cox regression analyses revealed that an increase of 1 SD of plasma log‐transformed homoarginine (0.37) was associated with a hazard reduction of 26% (hazard ratio [HR], 0.74; 95% CI, 0.57–0.96) for incident MACE and likewise of 35% (HR, 0.65; 95% CI, 0.49–0.88) in ACS patients. In Kaplan–Meier survival curves, homoarginine was predictive for patients with high‐sensitivity assayed troponin I (hsTnI) above 27 ng/L (P<0.05). Last, homoarginine was inversely associated with QTc duration (P<0.001) and prevalent AF (OR, 0.83; 95% CI, 0.71–0.95).
Conclusion Low plasma homoarginine was identified as a risk marker for incident MACEs in patients with acute chest pain, in particular, in those with elevated hsTnI. Impaired homoarginine was associated with prevalent AF. Further studies are needed to investigate the link to AF and evaluate homoarginine as a therapeutic option for these patients.
Die fremdsprachliche Spielfilmdidaktik geht der Frage nach, wie der Erwerb einer Sprache im Fremd-/Zweitsprachenunterricht durch den Einsatz von ganzen Spielfilmen oder von einzelnen Szenen und Sequenzen aus Spielfilmen gefördert werden kann. Sie formuliert entsprechende Lernziele, untersucht, ob bestimmte Filme für den fremdsprachlichen Unterricht geeignet sind, und entwickelt Lehrmaterialien mit Spielfilmen als zentralem Bestandteil.
Außerdem wird – bisher aber nur selten – die Wirkung des Filmeinsatzes auf die fremdsprachliche Kompetenz der Lernenden durch empirische Studien erforscht. Der eigentliche Beginn der fremdsprachlichen Spielfilmdidaktik lag in den Siebzigerjahren des vergangenen Jahrhunderts; die vorher erschienene Literatur beschäftigte sich fast ausschließlich mit der Verwendung von – zumeist speziell für den Unterricht produzierten – Kurzfilmen. Schrittmacher der fremdsprachlichen Spielfilmdidaktik war zunächst der Französischunterricht und dort vor allem der Literaturunterricht (Einsatz von Literaturverfilmungen).
Schon bald folgten jedoch Publikationen zu anderen Zielsprachen – vor allem zum Englisch-, Deutsch-als-Fremdsprache- und Spanischunterricht – sowie zu Filmen, die nicht auf literarischen Vorlagen basieren. Seitdem Spielfilme auf elektronischen Speichermedien (Videokassette und vor allem DVD/Blu-ray Disc) leicht verfügbar sind, ist die Zahl der einschlägigen Veröffentlichungen und der tatsächlich durchgeführten Unterrichtseinheiten deutlich angestiegen.
Naturgemäß geht es in den hier aufgelisteten Arbeiten in erster Linie um fremdsprachendidaktische Themenstellungen (z.B. Training des fremdsprachlichen Hör-Seh-Verstehens, Erwerb landeskundlicher Kenntnisse und interkulturelles Lernen, Förderung der fremdsprachlichen Sprech- und Schreibfertigkeit durch kreativ-produktive Auseinandersetzung mit den Filmen etc.), aber insbesondere in den Publikationen, die aus Deutschland stammen, wird häufig auch auf mediendidaktische Zielsetzungen (visual/ film literacy, Filmkompetenz) fokussiert. Diese Zielsetzungen sind seit einiger Zeit auch in etlichen deutschen Schullehrplänen verankert.
Die Dada-Bewegung entstand 1915 ungefähr gleichzeitig in Zürich aus der Gruppe von Literaten, Malern, Bildhauern um Hans Arp und in New York, angeführt durch Marcel Duchamp. Die Dadaisten versuchten, Anti-Kunst zu produzieren, sie stellten sich massiv gegen bürgerliche Konventionen in Gesellschaft, Geschmack und Kunst. Die Technik der Collage aus dem Kubismus wurde verbunden mit Strategien der Provokation und der Diffamierung der bürgerlich-idealistischen Kunst. Die Gruppe zerfiel anfangs der 1920er Jahre rasch, viele Dadaisten wandten sich dem Surrealismus zu. Die Bewegung lehnte sich insbesondere gegen die Konventionen der „bürgerlichen“ Kunst auf, polemisierte gegen den emotionsgeladenen Expressionismus und machte Kategorien wie Irrationalität und Kontingenz zur Programmatik einer nihilistischen Anti-Kunst. Mit ihren antireferentiellen und dekontextualisierenden Werken machten Dadaisten auf Sprach- und Gestaltungskonventionen aufmerksam, indem sie sie häufig ins Absurde führten. Beinahe sämtliche modernistischen Kunsttechniken (Collage, Assemblage, Aleatorik, Abstraktion, Integration indigener Kunst, Performance, Integration von Alltagsgegenständen und Populärkultur etc.) stammen aus der Dada-Bewegung.
Im Mai 2013 hat das japanische Parlament den Beitritt zum Haager Übereinkommen über die zivilrechtlichen Aspekte internationaler Kindesentführungen von 1980 beschlossen.
Dieses regelt das Verfahren, mit dem ein Kind nach einer Verbringung in einen anderes Land (z.B. durch einen Elternteil) gegen den Willen des Sorgeberechtigten wieder in das Land seines gewöhnlichen Aufenthaltes zurückgeführt wird. Die bisherige Handhabung Japans von internationalen Kindesentführungen führte zu starker Kritik aus dem Ausland.
Die Verfahren dauerten zu lange, so dass Fakten geschaffen wurden. Die japanische Rechtsprechung förderte indirekt die Entführung durch einen Elternteil und die Vollstreckung einer im Ausland erwirkten Rückführungsanordnung gestaltete sich schwierig.
Diese Arbeit versucht aufzuweisen, welche Umstände zu der Zurückhaltung der japanischen Regierung führten. Ein wichtiger Punkt hierbei ist, inwieweit eine Anpassung des inländischen Rechts für den Beitritt erforderlich ist. Formal ist eine Anpassung nicht nötig, allerdings führen Unterschiede im Rechtssystem zu Problemen in der Ausführung. Das japanische Familienrecht kennt z.B. im Gegensatz zu anderen Mitgliedsländern nach der Scheidung nur die alleinige Sorge. Auch das Recht auf Umgang ist nicht konkret geregelt.
Außerdem kommen Verbringungen innerhalb einer Familie bei einer drohenden Scheidung in Japan regelmäßig vor. Diese werden jedoch von den Gerichten nicht negativ gewertet.
Die Einführung einer kritischeren Bewertung von Verbringungen auf internationaler Ebene würde zu einer Diskrepanz mit den rein nationalen Fällen führen. Weitere Problematiken sind die Frage nach der strafrechtlichen Verfolgung der Verbringer sowie die Abwägung zwischen dem Prinzip der schnellen Rückführung und der Einschätzung des Kindeswohls.
Der vorliegende Beitrag ist eine Qualifikationsschrift im Bachelor-Studiengang Japanologie und versucht mittels kulturwissenschaftlicher Methoden eine Bestandsaufnahme der Aktivitäten städtischer Gärtner sowie der Nachhaltigkeitsstrategien in Tôkyô vorzunehmen.
Anhand der empirischen Auswertung von stadtpolitischen Nachhaltigkeitspapieren, Stellungnahmen eines Guerilla-Gärtners und Blogeinträgen einer Stadtfarmerin soll verdeutlicht werden, wie die einzelnen Akteure Stadt verstehen und diese durch ihre Praktiken konstruieren. Ziel ist es zu ermitteln, inwiefern Urban Gardening als Symptom für politische und gesellschaftliche Wandlungen verstanden werden kann.
Transport processes across the membrane are essential to ensure survival of every living cell. Therefore, the exchange of membrane impermeable molecules is mediated by specific transport proteins, which are embedded in the lipid bilayer.
One important class comprises secondary active transporters, which couple very efficiently the uphill transport of the main substrate against its concentration gradient to the downhill transport of an additional substrate. These transporters are widely distributed among all kingdoms of life and accomplish many crucial functions. One function is to counteract the deleterious effect of hyperosmotic stress in bacteria. Several members of the BCCT (betaine-choline-carnitinetransport) family of secondary transporters mediate osmostress protection by the accumulation of the compatible solute betaine or its precursor choline (Lamark et al., 1991; Peter et al., 1996; Ziegler et al., 2010). Besides osmo-dependent sodium or proton-coupled symporters, the BCCT family includes few rare representatives of osmo-independent transporters such as the substrate:product antiporter CaiT from E. coli (Jung et al., 2002; Ziegler et al., 2010).
The best-characterized member of the BCCT family is the sodium-coupled betaine transporter BetP from Corynebacterium glutamicum. BetP together with the ABCtransporter OpuA and the H+-solute symporter ProP, became a paradigm for osmoregulated osmolyte transport. Although, all three transporters were extensively studied, the general mechanism of osmoregulation is still far from being understood. Thus, one task of this thesis was to elucidate further the regulatory properties of BetP.
BetP is tightly regulated by osmotic stress and is able to increase its basal betaine uptake activity dramatically upon elevated osmolalities within one second (Peter et al., 1998a). The osmotic stress is sensed by BetP via two stimuli, one is the increase of the internal K+ concentration above a threshold of 220 mM (Rübenhagen et al., 2001), the second is related to a change in the physical state of the membrane (Maximov et al., 2014). So far, several solved crystal structures in combination with functional and computational analysis provided insights into the coupling mechanism of betaine and its co-substrate sodium (Khafizov et al., 2012; Perez et al., 2012). Despite the wealth of data, the precise regulatory mechanism of trimeric BetP is still unclear.
Different approaches are possible when it comes to modeling the brain. Given its biological nature, models can be constructed out of the chemical and biological building blocks known to be at play in the brain, formulating a given mechanism in terms of the basic interactions underlying it. On the other hand, the functions of the brain can be described in a more general or macroscopic way, in terms of desirable goals. This goals may include reducing metabolic costs, being stable or robust, or being efficient in computational terms. Synaptic plasticity, that is, the study of how the connections between neurons evolve in time, is no exception to this. In the following work we formulate (and study the properties of) synaptic plasticity models, employing two complementary approaches: a top-down approach, deriving a learning rule from a guiding principle for rate-encoding neurons, and a bottom-up approach, where a simple yet biophysical rule for time-dependent plasticity is constructed.
We begin this thesis with a general overview, in Chapter 1, of the properties of neurons and their connections, clarifying notations and the jargon of the field. These will be our building blocks and will also determine the constrains we need to respect when formulating our models. We will discuss the present challenges of computational neuroscience, as well as the role of physicists in this line of research.
In Chapters 2 and 3, we develop and study a local online Hebbian self-limiting synaptic plasticity rule, employing the mentioned top-down approach. Firstly, in Chapter 2 we formulate the stationarity principle of statistical learning, in terms of the Fisher information of the output probability distribution with respect to the synaptic weights. To ensure that the learning rules are formulated in terms of information locally available to a synapse, we employ the local synapse extension to the one dimensional Fisher information. Once the objective function has been defined, we derive an online synaptic plasticity rule via stochastic gradient descent.
In order to test the computational capabilities of a neuron evolving according to this rule (combined with a preexisting intrinsic plasticity rule), we perform a series of numerical experiments, training the neuron with different input distributions.
We observe that, for input distributions closely resembling a multivariate normal distribution, the neuron robustly selects the first principal component of the distribution, showing otherwise a strong preference for directions of large negative excess kurtosis.
In Chapter 3 we study the robustness of the learning rule derived in Chapter 2 with respect to variations in the neural model’s transfer function. In particular, we find an equivalent cubic form of the rule which, given its functional simplicity, permits to analytically compute the attractors (stationary solutions) of the learning procedure, as a function of the statistical moments of the input distribution. In this way, we manage to explain the numerical findings of Chapter 2 analytically, and formulate a prediction: if the neuron is selective to non-Gaussian input directions, it should be suitable for applications to independent component analysis. We close this section by showing how indeed, a neuron operating under these rules can learn the independent components in the non-linear bars problem.
A simple biophysical model for time-dependent plasticity (STDP) is developed in Chapter 4. The model is formulated in terms of two decaying traces present in the synapse, namely the fraction of activated NMDA receptors and the calcium concentration, which serve as clocks, measuring the time of pre- and postsynaptic spikes. While constructed in terms of the key biological elements thought to be involved in the process, we have kept the functional dependencies of the variables as simple as possible to allow for analytic tractability. Despite its simplicity, the model is able to reproduce several experimental results, including the typical pairwise STDP curve and triplet results, in both hippocampal culture and layer 2/3 cortical neurons. Thanks to the model’s functional simplicity, we are able to compute these results analytically, establishing a direct and transparent connection between the model’s internal parameters and the qualitative features of the results.
Finally, in order to make a connection to synaptic plasticity for rate encoding neural models, we train the synapse with Poisson uncorrelated pre- and postsynaptic spike trains and compute the expected synaptic weight change as a function of the frequencies of these spike trains. Interestingly, a Hebbian (in the rate encoding sense of the word) BCM-like behavior is recovered in this setup for hippocampal neurons, while dominating depression seems unavoidable for parameter configurations reproducing experimentally observed triplet nonlinearities in layer 2/3 cortical neurons. Potentiation can however be recovered in these neurons when correlations between pre- and postsynaptic spikes are present. We end this chapter by discussing the relation to existing experimental results, leaving open questions and predictions for future experiments.
A set of summary cards of the models employed, together with listings of the relevant variables and parameters, are presented at the end of the thesis, for easier access and permanent reference for the reader.