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Poster presentation at 1st International Workshop on Odor Spaces.
Mice are exceptional in their ability to capture their chemical environment, mapping the olfactory world into a basic sensory representation with over one thousand different types of chemical sensors, that is, olfactory sensory neurons (OSNs). OSNs of each type converge in the olfactory bulb onto exclusive distinct physiological areas called glomeruli. The glomeruli constitute the first relay station of olfactory stimulus representation in the mouse brain. Thus, the stimulus induced glomerular input pattern spatially embodies an important part of the sensory representation in the olfactory bulb. Still, topographic organization principles (chemotopy, tunotopy) are under debate. One reason might be that investigation are, due to experimental limitations, only performed on stimuli sets in the size of one hundred odors. But this represents only a tiny snapshot of the vast amount of molecules in the olfactory world and topographic relationships might be disguised in the incomplete representation of molecular receptive ranges (MRR). Therefore we investigated the problem with the MOR18-2 glomerulus as point of reference: First we determined it's MRR. Then, based on a measurement set covering this MRR, we elucidated the topographic embedding. It shows that MOR18-2 is embedded in a hierarchy of patchy tunotopic domains.
We have measured the radiative neutron-capture cross section and the total neutron-induced cross section of one of the most important isotopes for the s process, the 25Mg. The measurements have been carried out at the neutron time-of-flight facilities n_TOF at CERN (Switzerland) and GELINA installed at the EC-JRC-IRMM (Belgium). The cross sections as a function of neutron energy have been measured up to approximately 300 keV, covering the energy region of interest to the s process. The data analysis is ongoing and preliminary results show the potential relevance for the s process.
Poster presentation at The Twenty Third Annual Computational Neuroscience Meeting: CNS*2014 Québec City, Canada. 26-31 July 2014: We study random strongly heterogeneous recurrent networks of firing rate neurons, introducing the notion of cohorts: groups of co-active neurons, who compete for firing with one another and whose presence depends sensitively on the structure of the input. The identities of neurons recruited to and dropped from an active cohort changes smoothly with varying input features. We search for network parameter regimes in which the activation of cohorts is robust yet easily switchable by the external input and which exhibit large repertoires of different cohorts. We apply these networks to model the emergence of orientation and direction selectivity in visual cortex. We feed these random networks with a set of harmonic inputs that vary across neurons only in their temporal phase, mimicking the feedforward drive due to a moving grating stimulus. The relationship between the phases that carries the information about the orientation of the stimulus determines which cohort of neurons is activated. As a result the individual neurons acquire non-monotonic orientation tuning curves which are characterized by high orientation and direction selectivity. This mechanism of emergence for direction selectivity differs from the classical motion detector scheme, which is based on the nonlinear summation of the time-shifted inputs. In our model these two mechanisms coexist in the same network, but can be distinguished by their different frequency and contrast dependences. In general, the mechanism we are studying here converts temporal phase sequence into population activity and could therefore be used to extract and represent also various other relevant stimulus features.
Based on a non-rigorous formalism called the “cavity method”, physicists have made intriguing predictions on phase transitions in discrete structures. One of the most remarkable ones is that in problems such as random k-SAT or random graph k-coloring, very shortly before the threshold for the existence of solutions there occurs another phase transition called condensation [Krzakala et al., PNAS 2007]. The existence of this phase transition seems to be intimately related to the difficulty of proving precise results on, e. g., the k-colorability threshold as well as to the performance of message passing algorithms. In random graph k-coloring, there is a precise conjecture as to the location of the condensation phase transition in terms of a distributional fixed point problem. In this paper we prove this conjecture, provided that k exceeds a certain constant k0.
Impairment in past tense production as well as interaction between tense and aspect have been found in both fluent and non-fluent aphasia (e.g. Dragoy & Bastiaanse, 2013). Inflection has been found to be relatively preserved in semantic dementia (SD) (Thompson et al., 2012). The aims of the present study are a) to compare the morphosyntactic abilities of patients with aphasia and SD in tense and aspect marking and b) to explore the interaction of lexical (+/- telic) and grammatical (perfective/imperfective) aspect in aphasia and SD. A sentence completion task was administered to 30 native speakers of Greek: 10 patients with aphasia (6 anomic, 2 Wernicke and 2 agrammatic), 10 age and education-matched controls, 5 patients with SD and 5 controls. The material consisted of unergative, unaccusative and transitive verbs (12 of each verb class) and the participants had to apply present (imperfective) and past (perfective) tense. Unergative and unaccusative verbs differ in terms of their aspectual properties with the unergative being [-telic], and unaccusative [+telic]. Transitive verbs vary. A principal distinction between the tested conditions was the standard ummarked combination ([+telic] verbs in past perfective and [–telic] verbs in present imperfective) vs. the marked one ([+telic] verbs in present imperfective and [–telic] in past perfective). Both control groups performed at ceiling in all conditions. Aphasic participants were significantly more impaired than the control group in all conditions. SD participants were significantly more impaired than the controls only in the production of present tense (M-W U= 1.5, p= 0.024). There was no difference between past perfective and present imperfective for neither group, but there was an interaction between verb class and tense for the aphasic participants, as performance in unaccusative verbs in past perfective (unmarked condition) was significantly better than in unergatives in past perfective (marked condition) (Z=2.512, p=0.012) but performance in unaccusatives in present imperfective (marked condition) was significantly worse than performance in unergatives in present imperfective (unmarked condition) (Z=2.680, p=0.004). In sum, aphasic participants performed significantly better in the unmarked than in the marked conditions. Such an interaction was not found for the SD group. Aphasic participants performed significantly worse than the SD subjects in past perfective tense (M-W U= 7.5, p=0.029) in total, and the difference was significant only for unaccusative verbs (M-W U= 6.5, p=0.021), although both groups performed very well in this condition. There was no difference in present, neither for each verb class separately nor for the total score. A general past tense deficit cannot be upheld for either group. Rather, SD participants appear relatively impaired in producing present tense. We argue for slight morphosyntactic impairment in SD, although with a different underlying cause than in aphasia. Moreover, our data suggest an effect of aspectual markedness in aphasia but not in SD. We discuss this finding in the light of the different neuropathology of the two populations.
XIII Nuclei in the Cosmos, 7-11 July, 2014 Debrecen, Hungary.
As an alternative production scenario to the so-called g process, the most abundant p nucleus 92Mo may be produced by a chain of proton-capture reactions in supernovae type Ia. The reactions 90Zr(p,g) and 91Nb(p,g) are the most important reactions in this chain. We have measured the first reaction using high-resolution in-beam g-spectroscopy at HORUS, Cologne, Germany, to contribute to the existing experimental data base. So far, we only investigated the high-energy part of the Gamow window and the analysis is still in progress. We plan to study the second reaction in standard kinematics at the FRANZ facility, Frankfurt, Germany. Current developments at FRANZ will be explained in detail.
Modeling the effects of neuronal morphology on dendritic chloride diffusion and GABAergic inhibition
(2014)
Poster presentation at the Twenty Third Annual Computational Neuroscience Meeting: CNS*2014 Québec City, Canada. 26-31 July 2014.
Gamma-aminobutyric acid receptors (GABAARs) are ligand-gated chloride (Cl−) channels which mediate the majority of inhibitory neurotransmission in the CNS. Spatiotemporal changes of intracellular Cl− concentration alter the concentration gradient for Cl− across the neuronal membrane and thus affect the current flow through GABAARs and the efficacy of GABAergic inhibition. However, the impact of complex neuronal morphology on Cl− diffusion and the redistribution of intracellular Cl− is not well understood. Recently, computational models for Cl− diffusion and GABAAR-mediated inhibition in realistic neuronal morphologies became available [1-3]. Here we have used computational models of morphologically complex dendrites to test the effects of spines on Cl− diffusion. In all dendritic morphologies tested, spines slowed down longitudinal Cl− diffusion along dendrites and decreased the amount and spatial spread of synaptically evoked Cl− changes. Spine densities of 2-10 spines/µm decreased the longitudinal diffusion coefficient of Cl− to 80-30% of its value in smooth dendrites, respectively. These results suggest that spines are able to limit short-term ionic plasticity [4] at dendritic GABAergic synapses.
We present the results of two-pion production in tagged quasi-free np collisions at a deutron incident beam energy of 1.25 GeV/c measured with the High-Acceptance Di-Electron Spectrometer (HADES) installed at GSI. The specific acceptance of HADES allowed for the first time to obtain high-precision data on π+π− and π−π0 production in np collisions in a region corresponding to large transverse momenta of the secondary particles. The obtained differential cross section data provide strong constraints on the production mechanisms and on the various baryon resonance contributions (∆∆, N(1440), N(1520), ∆(1600)). The invariant mass and angular distributions from the np → npπ+π −and np → ppπ−π0 reactions are compared with different theoretical model predictions.
Europeana provides a common access point to digital cultural heritage objects across different cultural domains among which the libraries. The recent development of the Europeana Data Model (EDM) provide new ways for libraries to experiment with Linked Data. Indeed the model is designed as a framework reusing various wellknown standards developed in the Semantic Web Community, such as the Resource Description Framework (RDF), the OAI Object Reuse and Exchange (ORE), and Dublin Core namespaces. It provides new opportunities for libraries to provide rich and interlinked metadata to the Europeana aggregation.
However to be able to provide data to Europeana, libraries need to create mappings from the librarystandard to EDM. This step involves decisions based on domainspecific requirements and on the possibilities offered by EDM. The crossdomain nature of EDM limiting in some cases the completeness of the mappings, extension of the model have been proposed to accommodate the library needs.
The "Digitised Manuscripts to Europeana" project (DM2E) has created an extension of EDM to optimise the mappings of librarydata for manuscripts. This extension is in the form of subclasses and subproperties that further specialise EDM concepts and properties. It includes spatial creation and publishing information, specific contributor and publication type properties and more.
Furthermore the granularity of the mapping has been extended to allow references and annotations on page level as required for scholarly work. As part of this project the metadata of the Hebrew Manuscripts as well as of the Medieval Manuscripts presented in the Digital Collections of the Frankfurt University Library have been mapped to this extension. This includes links to the Integrated Authority File (GND) of the German National Library with further links to the Virtual International Authority File (VIAF).
Based on this development a new comprehensive mapping from the digitalisation metadata format METS/MODS to EDM has been established for all materials of the Frankfurt Judaica in "Judaica Europeana ". It demonstrates today’s capabilities of the creation of linked Data structures in Europeana based on library catalogue data and structural data from the digitalisation process.
D2.1. provides further elaboration of the original research design and informs about ideas for the final Volume II of bEUcitizen. It is closely connected to task 1 of work package 2: specifying various concrete tasks for the different work packages and formulating overarching questions suitable to provide substantive cohesion and integration of the overall project. The elaboration of 10 crosscutting topics (to become chapters in the “horizontal” book, D2.3.) is a first step towards this goal. Discussing these cross-cutting topics is supposed to feed, infuse and inspire the work done in the different work packages and to build cross-cutting connections between them. Themes 1-10 merge into a valuable overview of the multi-faceted research on (EU) citizenship. They access the main issues of EU-citizenship and citizenship in general from different angles and different disciplines. Taken together these contributions help to identify barriers towards EU citizenship and ways to overcome them. Each Theme formulates questions how it might feed and be fed by further information and findings in the other work packages.
D2.1. is mainly meant for internal use. Its functions are firstly to inform about preliminary ideas, eventual contributions to planned final results and secondly to make out some more of less specific guiding questions that connect the work done by the single researchers in every different work package to the project as a whole. This task implies a normative yardstick, a clear picture of what would be a "good" EU citizenship practice. Elaborating on such a normative yardstick is a meta-topic that cuts across the range of cross-cutting topics presented in this working paper.