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See detailModular Hydrokinetic Micro Generation
Norta, David Peter Benjamin UL; Sachau, Jürgen UL; Allelein, Hans-Josef

Poster (2013, October 07)

Detailed reference viewed: 127 (14 UL)
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See detailEmotion regulation in Autism Spectrum Disorder: A review
Pinto Costa, Andreia UL; Steffgen, Georges UL

Poster (2013, October)

Introduction: Emotion regulation is an important aspect of children emotional and social development. Especially, children with autism spectrum disorder (ASD) seem to be at a disadvantage regarding ... [more ▼]

Introduction: Emotion regulation is an important aspect of children emotional and social development. Especially, children with autism spectrum disorder (ASD) seem to be at a disadvantage regarding emotion regulation due to social interaction difficulties. In the present study we review the research findings on the specific emotion regulation strategies in children with ASD. Participants and Methods: We carried out literature searches using Primo Central ExLibris for all articles published on emotion regulation in children with ASD since 2003. Articles were included if they met the following criteria: a) comprised participants with ASD under the age of 18 years; b) contained empirical research findings on emotion regulation; and c) used a prospective group comparison design. At the end, the review includes 12 independent studies. Results: In general, findings indicate that children with ASD use less emotion regulation strategies than typically developing peers. However, some studies prove less efficient strategies in children with ASD, while others did not find differences. In studies analysing the impact of interventions, children show diminished expression of negativity and more appropriate emotion regulation during post-treatment. Conclusion: Emotion regulation difficulties are a serious concern for children with ASD, yet empirical studies on this topic are still scarce. More studies with larger samples are needed. Especially, other characteristics, such as social interaction and caregiver’s intervention, that might influence emotion regulation have to be further analysed. [less ▲]

Detailed reference viewed: 193 (15 UL)
Peer Reviewed
See detailEstimation abilities of large numerosities in preschool children
Mejias, Sandrine; Schiltz, Christine UL

Poster (2013, October)

The approximate number system (ANS) is thought to be a building block for the elaboration of formal mathematics. However, little is known about how this core system develops and if it can be influenced by ... [more ▼]

The approximate number system (ANS) is thought to be a building block for the elaboration of formal mathematics. However, little is known about how this core system develops and if it can be influenced by external factors at a young age (before the child enters formal numeracy education). The purpose of this study was to examine numerical magnitude representations of 5-6 year old children at 2 different moments of Kindergarten considering children's early number competence as well as schools' socio-economic index (SEI). This study investigated estimation abilities of large numerosities using symbolic and non-symbolic output formats (8-64). In addition, we assessed symbolic and non-symbolic early number competence (1-12) at the end of the 2nd (N = 42) and the 3rd (N = 32) Kindergarten grade. By letting children freely produce estimates we observed surprising estimation abilities at a very young age (from 5 year on) extending far beyond children's symbolic explicit knowledge. Moreover, the time of testing has an impact on the ANS accuracy since 3rd Kindergarteners were more precise in both estimation tasks. Additionally, children who presented better exact symbolic knowledge were also those with the most refined ANS. However, this was true only for 3rd Kindergarteners who were a few months from receiving math instructions. In a similar vein, higher SEI positively impacted only the oldest children's estimation abilities whereas it played a role for exact early number competences already in 2nd and 3rd graders. Our results support the view that approximate numerical representations are linked to exact number competence in young children before the start of formal math education and might thus serve as building blocks for mathematical knowledge. Since this core number system was also sensitive to external components such as the SEI this implies that it can most probably be targeted and refined through specific educational strategies from preschool on. [less ▲]

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See detailDesign principles study of ROS management and ROS-induced mitophagy with a kinetic model
Kolodkin, Alexey UL; Ignatenko, Andrew UL; Sangar, Vineet et al

Poster (2013, September 27)

In vivo evidence demonstrates three fundamental interconnected adaptive survival mechanisms , which protect against excessive ROS that is generated during mitochondrial dysfunction: (i) autophagy ... [more ▼]

In vivo evidence demonstrates three fundamental interconnected adaptive survival mechanisms , which protect against excessive ROS that is generated during mitochondrial dysfunction: (i) autophagy/mitophagy, (ii) adaptive antioxidant response and (iii) NFkB signaling in cancer and neurodegeneration. We have been expanding a kinetic model which recapitulates the consensus understanding of the mechanisms responsible for cellular ROS – management system and performed modular analysis to analyze emergent behavior. We started with the simplest model and added stepwise new modules. We identify the qualitative role (certain emergent behavior) attributed to each module and thus understand the design principles of the system. We propose a detailed, mechanistic, kinetic model for studying how mutations relevant for diseases such as PD and cancer affect the emergent behavior of ROS management network. [less ▲]

Detailed reference viewed: 294 (11 UL)
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See detailA Bayesian Monte Carlo Markov Chain Method for the Statistical Analysis of Geodetic Time Series
Olivares Pulido, German UL; Teferle, Felix Norman UL

Poster (2013, September 06)

Geodetic time series provide information which help to constrain theoretical models of geophysical processes. It is well established that such time series, for example from GPS or gravity measurements ... [more ▼]

Geodetic time series provide information which help to constrain theoretical models of geophysical processes. It is well established that such time series, for example from GPS or gravity measurements, contain time-correlated noise which is usually assumed to be a combination of a long-term stochastic process (characterized by a power-law spectrum) and random noise. Therefore, when fitting a model to geodetic time series it is essential to also estimate the stochastic parameters beside the deterministic ones. In many cases the stochastic parameters have included the power amplitudes of both time-correlated and random noise as well as the spectral index of the power-law process. To date the most widely used method for obtaining these model parameter estimates is based on maximum likelihood estimation (MLE). We present a new Bayesian Monte Carlo Markov Chain (MCMC) method to estimate the deterministic and stochastic model parameters of geodetic time series. This method provides a sample of the likelihood function and thereby, using Monte Carlo integration, all parameters and their uncertainties are estimated simultaneously. One advantage of this method over MLE is that the computation time required increases linearly with the number of parameters, hence being very suitable for dealing with a large number of parameters. Another advantage is that the properties of the estimator used by the MCMC method do not depend on the stationarity of the time series. We assess the MCMC method through comparison with MLE, using a data set of 300 synthetic GPS-like time series and the JPL daily position time series for 90 GPS stations (the IGS core network). [less ▲]

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See detailPotential Contributions to Geoscience from GNSS Observations of the King Edward Point Geodetic Observatory, South Georgia, South Atlantic Ocean
Teferle, Felix Norman UL; Hunegnaw, Addisu UL; Ahmed, Furqan UL et al

Poster (2013, September 01)

During February 2013 the King Edward Point (KEP) Geodetic Observatory was established in South Georgia, South Atlantic Ocean, through a University of Luxembourg funded research project and in ... [more ▼]

During February 2013 the King Edward Point (KEP) Geodetic Observatory was established in South Georgia, South Atlantic Ocean, through a University of Luxembourg funded research project and in collaboration with the United Kingdom’s National Oceanography Centre, British Antarctic Survey and Unavco, Inc. Due to its remote location in the South Atlantic Ocean, as well as, being one of few subaerial exposures of the Scotia plate, South Georgia Island has been a key location for a number of global monitoring networks, e.g. seismic, geomagnetic and oceanic. However, no geodetic monitoring station has been established, e.g. by the International Global Navigation Satellite System (GNSS) Service (IGS) community, despite the lack of such observations from this region. In this study we will present an evaluation of the GNSS observations from the KEP Geodetic Observatory for the period from February to August 2013. We calculate multipath and positioning statistics and compare these to those from IGS stations. The on-site meteorological data is compared to those from the nearby KEP meteorological station and global numerical weather models, and the impact of these data sets on delay and integrated water vapour estimates will be evaluated. We will discuss the installation in terms of its potential contributions to sea level observations using tide gauges and satellite altimetry, studies of tectonics, glacio-isostatic adjustment and atmospheric processes. [less ▲]

Detailed reference viewed: 94 (14 UL)
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See detailAntenna phase centre calibration effects on position time-series: preliminary results
Sidorov, Dmitry UL; Teferle, Felix Norman UL

Poster (2013, September 01)

Advances in GPS error modelling and the continued effort of re-processing have considerably decreased the scatter in position estimates over the last two decades. The associated reduction of noise in ... [more ▼]

Advances in GPS error modelling and the continued effort of re-processing have considerably decreased the scatter in position estimates over the last two decades. The associated reduction of noise in derived position time-series has revealed the presence of previously undetected periodic signals. It has been shown that these signals have frequencies related to the orbits of GPS satellites. A number of potential sources for these periodicities at the draconitic frequency and its harmonics have already been suggested in the literature and include, e.g. errors in the sub-daily tidal models, multipath and unresolved integer ambiguities. Due to the geometrical relationship between an observation point and an orbiting satellite, deficiencies in the modelling of electromagnetic phase centres of receiving antennas have the potential to also contribute to the discovered periodic signals. The change from relative to absolute type mean antenna/radome calibrations within the international GNSS service (IGS) lead to a significant improvement and the use of individual calibrations could add further refinements to computed solutions. However, at this stage providing individual calibrations for all IGS stations is not feasible. Furthermore, antenna near-field electromagnetic effects might out-weight the benefits of individual calibrations once an antenna is permanently installed. In this study we investigate the differences between position estimates obtained using individual and type mean antenna/radome calibrations as used by the IGS community. We employ position time-series derived from precise point positioning (PPP) as implemented in two scientific GNSS software packages. Our results suggest that the differences in the employed calibrations propagate directly into the position estimates, affecting both sub-daily and daily results and yielding periodic variations. The sub-daily variations have periods close to half a sidereal day and one sidereal day with amplitudes of up to 10 mm in all position components. The stacked power spectra of the daily difference time-series reveal peaks at the GPS draconitic frequency and its harmonics, having the associated amplitudes of up to 1 mm. Although these results are still preliminary, they confirm that small differences between individual and type mean antenna/radome calibrations propagate into position time series and may be partly responsible for the spurious signals with draconitic frequency and its harmonics. [less ▲]

Detailed reference viewed: 125 (22 UL)
See detailEffizienz gleich Leistung? Analyse des Antwortverhaltens bei einem distraktorfreien Matrizentest.
Krieger, Florian UL; Kirmße, Alexander; Spinath, Frank M. et al

Poster (2013, September)

Anwendung effizienter Bearbeitungsstrategien abhängt. Bisherige Studien zeigen, dass strukturiertes und sequentielles Bearbeiten der Gestaltungsregeln nach aufsteigender Schwierigkeit zu einer besseren ... [more ▼]

Anwendung effizienter Bearbeitungsstrategien abhängt. Bisherige Studien zeigen, dass strukturiertes und sequentielles Bearbeiten der Gestaltungsregeln nach aufsteigender Schwierigkeit zu einer besseren Leistung führt. Während Bearbeitungsstrategien bislang durch Blickbewegungsstudien, Computersimulationen und die Methode des lauten Denkens ermittelt wurden, wurde in dieser Studie die Matrizenkonstruktionsaufgabe verwendet, bei der die Lösung in einer computerisierten Testumgebung generiert wird. Dies ermöglicht eine zeitgenaue und objektive Aufzeichnung des Prozesses der Antwortgenerierung. In Antwortprotokollen von 480 Probanden konnte mittels verschiedener Prozessindikatoren (Regelsprünge, Abweichung von erwarteter Bearbeitungsreihenfolge, Zurücksetzen generierter Lösungen, Ausmaß der Verwendung relevanter Gestaltungselemente) in einer multiplen Regression bis zu 28.8 % der Varianz der Testleistung aufgeklärt werden. Insbesondere strukturiertes und sequentielles Bearbeiten von Gestaltungsregeln sowie der Ausschluss irrelevanter Gestaltungselemente sind entscheidend für eine bessere Leistung. Entgegen bisheriger Befunde zeigt sich jedoch, dass die Bearbeitungsreihenfolge der Gestaltungsregeln nicht auf einer allgemeingültigen Schwierigkeit der Gestaltungsregeln beruht. [less ▲]

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See detailAssessing the Status of GNSS Data Processing Systems to Estimate Integrated Water Vapour for Use in Numerical Weather Prediction models
Ahmed, Furqan UL; Teferle, Felix Norman UL; Bingley, Richard et al

Poster (2013, September)

Modern Numerical Weather Prediction (NWP) models make use of the GNSS derived Zenith Total Delay (ZTD) or Integrated Water Vapour (IWV) estimates to enhance the quality of their forecasts. Usually, the ... [more ▼]

Modern Numerical Weather Prediction (NWP) models make use of the GNSS derived Zenith Total Delay (ZTD) or Integrated Water Vapour (IWV) estimates to enhance the quality of their forecasts. Usually, the ZTD is assimilated into the NWP models on hourly intervals but with the advancement of NWP models towards higher update rates, it has become necessary to estimate the ZTD on sub-hourly intervals. In turn, this imposes requirements related to the timeliness and accuracy of the ZTD estimates and has lead to a development of various strategies to process GNSS observations to obtain ZTD with different latencies and accuracies. Using present GNSS products and tools, ZTD can be estimated in real-time (RT), near real-time (NRT) and post-processing (PP) modes. The aim of this study is to provide an overview and accuracy assessment of various RT, NRT, and PP IWV estimation systems and comparing their achieved accuracy with the user requirements for GNSS meteorology. The NRT and PP systems are based on the Bernese GNSS Software v5.2 using a double-difference network and Precise Point Positioning (PPP) strategy, and the RT systems are based on BKG Ntrip Client 2.7 and PPP-Wizard both using PPP. One of the RT systems allows integer ambiguity resolution with PPP and therefore the effect of fixing integer ambiguities on ZTD estimates will also be presented. [less ▲]

Detailed reference viewed: 160 (11 UL)
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See detailBoundary elements for modelling gravitational signals observed by inter-satellite ranging
Antoni, M.; Weigelt, Matthias UL; Keller, W. et al

Poster (2013, September)

Detailed reference viewed: 58 (7 UL)
See detailEffect of grafted alumina nanoparticles on thermal and dynamic mechanical properties of the styrene-butadiene rubber
Sushko, Rymma UL; Baller, Jörg UL; Filimon, Marlena UL et al

Poster (2013, September)

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile ... [more ▼]

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile strength etc. The smaller the size of the particles the larger is the interface where interactions between polymer molecules and fillers can generate new properties. The aim of this contribution is to study the influence of the fillers’ surface treatment on the thermal and mechanical behavior of nanocomposites made of styrene-butadiene rubber (SBR). Three types of nanocomposites are investigated : (i) SBR-unmodified alumina, (ii) SBR – silanized alumina and (iii) SBR – alumina grafted to polymer chains. The surface-modified alumina nanoparticles were prepared using the method described in [1]. The grafting of the SBR chains to the alumina nanoparticles was realized by means of the procedures described in [2] and [3]. Temperature Modulated Differential Scanning Calorimetry (TMDSC) and Dynamic Mechanical Analysis (DMA) are well appropriated tools to investigate the thermal and dynamic glass transition behavior of the different nanocomposites, which is expected to be very sensitive to interfacial interactions between the nanoparticles and matrix molecules. TMDSC experiments reveal that all of the nanocomposites undergo a single glass transition. Thus, interphases induced by interfacial interactions do not manifest themselves by an additional glass transition unless it is hidden by the one of the matrix. Moreover, TMDSC measurements reveal that in general the glass transition temperature Tg depends in a complex manner on the concentration and surface treatment of the nanoparticles. The most important change of Tg is observed for the grafted nanocomposites: increasing the nanoparticle weight concentration beyond 4% yields an increase of Tg by 4 K. The corresponding slowing down of the molecular dynamics goes along with a significant decrease of the relaxator strength. More generally the presented results prove that, at the same filler concentration, the number of degrees of freedom freezing at the glass transition in case of un-grafted systems is practically independent on the chemical nature of the particles surface whereas it changes when there exist covalent bonds between the polymer molecules and the nanoparticles. DMA was used to probe the rheological behaviour of the nanocomposites under oscillatory shear. Isothermal frequency sweeps performed at different temperatures yield the real (G’) and imaginary (G”) parts of the complex shear modulus. Linear response regime conditions were strictly respected. The temperature-frequency equivalence principle was exploited to construct mastercurves for G’ and G” at the reference temperature T=273 K. As usual in polymers, three different behaviors were observed: the dynamic glass transition at high frequencies, the entanglement plateau at intermediary frequencies and viscoelastic “flowing” at very low frequencies. It generally appears that the filling of the SBR matrix with nanoparticles leads to an increase of the storage modulus that is more prominent in the rubbery region than in the glassy segment. While, in the low frequency regime, untreated and silanized alumina yield a mechanical behaviour that is rather near to the one of the neat SBR matrix, the grafting of elastomer molecules to the silanized fillers obviously induces a quasi-solid like response of the system. References: 1. Y.-Ch. Yang, S.-B. Jeong, B.-G. Kim, P.-R. Yoon, Powder Technology, 191, 117–121, 2009. 2. E. Passaglia, F. Donati, Polymer, 48, 35-42, 2007. 3. A. Bhattacharya, B. Misra, Prog. Polym. Sci. 29, 767–814, 2004. [less ▲]

Detailed reference viewed: 97 (3 UL)
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See detailFluctuation Relations and Crystallization in Colloidal Suspensions
Dorosz, Sven UL

Poster (2013, September)

Hard Spheres undergo a fluid to solid phase transition if the packing fraction is above $0.5$. The nucleation process itself and developing structures in this transient process are still matter of current ... [more ▼]

Hard Spheres undergo a fluid to solid phase transition if the packing fraction is above $0.5$. The nucleation process itself and developing structures in this transient process are still matter of current research. \\ Here a new approach is proposed to correlate forming structure and dissipation directly. The system driven externally by a time varying pressure is compressed in a finite time. Thermodynamic work measured and directly correlated to structural information recorded during the process. Fluctuation theorems set the framework of this analysis that still hold at the first order phase transition that are initialized by a macroscopic fluctuation. [less ▲]

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See detailAutistic traits and emotion regulation
Pinto Costa, Andreia UL; Steffgen, Georges UL

Poster (2013, September)

Introduction: Individuals with Autism Spectrum Disorder (ASD) seem to have lower emotion regulation competence than typically developing individuals; they use more frequently suppression than reappraisal ... [more ▼]

Introduction: Individuals with Autism Spectrum Disorder (ASD) seem to have lower emotion regulation competence than typically developing individuals; they use more frequently suppression than reappraisal (Samson, Huber, & Gross, 2012). Additionally, low levels of resting heart rate variability (HRV) have been associated with poor social functioning and emotional rigidity (Butler, Wilhelm, & Gross, 2006), which characterize individuals with ASD. Therefore, it is hypothesized that typically developing individuals with more autistic traits use more frequently suppression instead of reappraisal and have lower resting HRV. Methodology: 66 students (age: M=21.73, SD=2.49) participated in the study. Firstly, participants resting HRV was measured for 5 minutes. Afterwards, participants watched 5 videos of one minute long each (Gross & Levenson, 1995). Two videos were used to elicit disgust and three were neutral. After each video, participants completed a questionnaire about the emotions felt during the video (Ekman, Friesen, & Ancoli, 1980; adapted by Gross & Levenson, 1993). Finally, participants completed the Autism-Spectrum Quotient (AQ; Baron-Cohen et al., 2001), and the Emotion Regulation Questionnaire (ERQ; Gross & John, 2003). Results: Participants who used more frequently suppression had more autistic traits (M=20.13, SD=4.73) than those who used more frequently reappraisal (M=15.06, SD=4.50; t(64)=3.80, p<.001). Furthermore, the more autistic traits participants had, the more they rated their emotions during the disgust-eliciting videos as pleasant (r(57)=.295, p<.05), and the more they reported feeling positive emotions (r(63)=.262, p<.05). However, no correlation was found regarding negative emotions. Concerning resting HRV participants with more autistic traits had higher HRV (r(47)=.29, p<.05). Conclusions: Similarly to individuals with ASD, typically developing individuals with more autistic traits used more frequently suppression, demonstrating less emotion regulation competence. The reported higher rates of pleasantness during the disgust-eliciting videos and the overall experience of more positive emotions can be interpreted as a lack of cognitive empathy (Baron-Cohen & Wheelwright, 2004). The unexpected resting HRV result might be explained by differences in the pattern of physiological responding (Zahn, Rumsey, & Kammen, 1987). [less ▲]

Detailed reference viewed: 212 (22 UL)
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See detailFluctuation Relations and Crystallization
Dorosz, Sven UL

Poster (2013, August)

Hard Spheres undergo a fluid to solid phase transition if the packing fraction is approx. $>0.5$. The nucleation process itself and structure formation in this transient process are still under ... [more ▼]

Hard Spheres undergo a fluid to solid phase transition if the packing fraction is approx. $>0.5$. The nucleation process itself and structure formation in this transient process are still under investigation. Here a new approach is proposed to correlate forming structure and dissipation directly. Fluctuation relations are the method of choice. Increasing the pressure with time results in thermodynamic work, linked by the first law of thermodynamics to dissipation.\\ Studying fluctuation relations of structural phase transition and even slow dynamics is important. A new kind of fluctuation enters the dynamics that is macroscopic instead of microscopic based on thermal fluctuations. [less ▲]

Detailed reference viewed: 58 (1 UL)
Peer Reviewed
See detailModeling cellular ROS defense in mitochondrial-related diseases
Simeonidis, Vangelis UL; Kolodkin, Alexey UL; Ignatenko, Andrew UL et al

Poster (2013, July 22)

Reactive Oxygen Species (ROS) generation is an unavoidable background process during normal cellular function. The main contributor to ROS production is the electron transport chain, which reduces oxygen ... [more ▼]

Reactive Oxygen Species (ROS) generation is an unavoidable background process during normal cellular function. The main contributor to ROS production is the electron transport chain, which reduces oxygen to water. Some incompletely-reduced oxygen species escape and oxidize a variety of organic molecules, leading to molecular dysfunction and initiating a positive feedback loop of ever increasing active radical production. The increased concentration of ROS damages the mitochondria, therefore further elevating the rate of ROS generation. Healthy cells manage ROS enzymatically and by mitophagy of damaged mitochondria. The precise tuning of the latter mechanism is crucial for cell survival and is controlled by a ROS-induced regulatory network. We have built a set of kinetic models of varying complexity, based on the current understanding of the mechanism of cellular ROS defense. Our models allow simulation of various patho-physiological scenarios related to mitochondrial dysfunction and the failure of the system of ROS regulation in human cells. We employ the models we have constructed to simulate the effects of diseases related to mitochondrial dysfunction and excessive ROS generation, such as Parkinson’s disease, Huntington’s disease and cancer. Experimental evidence is used for model fitting, and we propose model improvements based on incorporation of single-cell experimental measurements. Finally, we discuss the perspective of integrating our kinetic models with genome-scale, constraint-based, tissue-specific models of metabolism, in order to study the effect of ROS misregulation on metabolic phenotype. [less ▲]

Detailed reference viewed: 160 (5 UL)
Peer Reviewed
See detailBilingualism Enriches the Poor: Enhanced Cognitive Control in Low-Income Minority Children
Engel de Abreu, Pascale UL; Cruz-Santos, A; Tourinho De Abreu Neto, Carlos José UL et al

Poster (2013, June 24)

This study explores whether the cognitive advantage associated with bilingualism in executive functioning extends to young children challenged by poverty and if so, which specific processes are most ... [more ▼]

This study explores whether the cognitive advantage associated with bilingualism in executive functioning extends to young children challenged by poverty and if so, which specific processes are most affected. Forty Portuguese-Luxembourgish bilingual children from low-income immigrant families in Luxembourg and 40 matched monolingual children from Portugal completed visuo-spatial tests of working memory, abstract reasoning, selective attention, and interference suppression. Two broad cognitive factors of executive functioning labeled representation (abstract reasoning and working memory) and control (selective attention and interference suppression) emerged from principal components analysis. Whereas there were no group differences in representation, the bilinguals performed significantly better than the monolinguals in control. These results demonstrate first, that the bilingual advantage is neither confounded with nor limited by socioeconomic and cultural factors and second, that separable aspects of executive functioning are differentially affected by bilingualism. The bilingual advantage lies in control but not in visuo-spatial representational processes. [less ▲]

Detailed reference viewed: 111 (14 UL)
See detailAnomalous behaviour of SBR/Al2O3 nanocomposites at small filler concentrations
Sushko, Rymma UL; Baller, Jörg UL; Filimon, Marlena UL et al

Poster (2013, June)

Elastomers filled with hard nanoparticles are of great importance for the rubber industry. In general, the incorporation of the small particles improves the mechanical properties of polymeric materials, e ... [more ▼]

Elastomers filled with hard nanoparticles are of great importance for the rubber industry. In general, the incorporation of the small particles improves the mechanical properties of polymeric materials, e.g. elastic modulus, tensile strength etc. Nanocomposites made of poly(styrene-co-butadiene) and alumina nanoparticles (unmodified and modified with different silane coupling agents) were investigated by temperature modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA). It has been shown that the glass transition behaviour of SBR/alumina nanocomposites differs when the concentration and surface properties of the Al2O3 nanoparticles are changed. The influence of the fillers on the shear stiffness of the rubber material was also investigated. TMDSC investigations shed light on a surprising behaviour of the glass transition temperature when the nanoparticle concentration is changed: at low filler contents the quasi-static glass transition temperature Tg passes through a minimum. While further increasing the nanoparticle content Tg increases to finally saturate at high concentrations. DMA results showed a quasi-solid-like frequency-independent response of the nanocomposites in the low frequency regime with increasing of the filler concentration. [less ▲]

Detailed reference viewed: 66 (2 UL)
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See detailModifications of the Simpson moduli spaces of 1-dimensional sheaves on a projective plane by vector bundles
Iena, Oleksandr UL

Poster (2013, June)

We study how to modify the Simpson moduli spaces of 1-dimensional coherent sheaves on a projective plane in order to obtain a space of vector bundles on curves.

Detailed reference viewed: 30 (1 UL)
Peer Reviewed
See detailHow the human brain discriminates numerosities: A steady-state visual-evoked potentials study
Mejias, Sandrine; Rossion, Bruno; Schiltz, Christine UL

Poster (2013, May 28)

This study aimed at measuring rapidly and objectively human adults' sensitivity to (non)symbolic numerical stimuli, using the steady-state visual-evoked potentials (1) response in the context of ... [more ▼]

This study aimed at measuring rapidly and objectively human adults' sensitivity to (non)symbolic numerical stimuli, using the steady-state visual-evoked potentials (1) response in the context of repetition suppression (2). It aimed to demonstrate the feasibility of the method and evaluate its potential to tap into the basic numerical representation systems that can be assumed to underlie symbolic and non-symbolic magnitude comparisons. Following a short duration experiment, we observed a large reduction of signal specifically at the 3.5 Hz response, over the occipito-temporo-parietal cortex. This reduction was greater for symbolic than non-symbolic control stimuli. This first observation of repetition suppression to fast periodic stimulation of symbolic and non-symbolic numerosities in the human brain offers a promising tool to study the sensitivity to numerosities in the human brain in adults, but also especially in children. [less ▲]

Detailed reference viewed: 31 (1 UL)
Peer Reviewed
See detailMental disorders and personality characteristics in parents of patients with eating disorders
Rost, Silke UL; Kappel, Viola; Schneider, Nora et al

Poster (2013, May 25)

Detailed reference viewed: 33 (2 UL)
See detailRelaxation times and electron-phonon interaction in graphene quantum dots
Reichardt, Sven UL; Volk, Christian; Neumann, Christoph et al

Poster (2013, May 23)

Detailed reference viewed: 82 (2 UL)
Peer Reviewed
See detailSpezifität der Körperbildstörung für Anorexia nervosa
Rost, Silke UL; Jaite, Charlotte; Sarrar, Lea et al

Poster (2013, May 10)

Detailed reference viewed: 86 (6 UL)
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Peer Reviewed
See detailA Library for Event-Processing and Adaptable Component Interactions in Autonomous Robot Software
Ziafati, Pouyan UL; Voos, Holger UL; van der Torre, Leon UL et al

Poster (2013, May 06)

A light-weight framework-independent software library is introduced to facilitate a modular and systematic development of sensory management components for an autonomous robot. Such components are used to ... [more ▼]

A light-weight framework-independent software library is introduced to facilitate a modular and systematic development of sensory management components for an autonomous robot. Such components are used to implement complex eventprocessing tasks such as content-based filtering, integration and transformation of sensory data. In addition, they can be used as mediators to provide a number of high-level interaction mechanisms among a robot’s software components. To this end, they enable components with subscription to their events of interest, asynchronous reception of events, maintaining necessary histories of events and querying of the histories at runtime. [less ▲]

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Peer Reviewed
See detailExecutive functions in language-minority children with specific language impairment
Engel de Abreu, Pascale UL; Cruz-Santos, A; Puglisi, M

Poster (2013, May)

This study explored executive function skills and language abilities in bilingual immigrant children with specific language impairment (SLI) from low income families in Luxembourg. Data from 81 eight-year ... [more ▼]

This study explored executive function skills and language abilities in bilingual immigrant children with specific language impairment (SLI) from low income families in Luxembourg. Data from 81 eight-year-olds from three different groups were analyzed: (1) 15 Portuguese-Luxembourgish children with SLI living in Luxembourg (Bi-SLI); (2) 33 typically developing Portuguese-Luxembourgish bilinguals from Luxembourg (Bi-TD); (3) 33 typically developing monolinguals from Portugal (Mo-TD). Groups were matched on first language, chronological age, and socioeconomic status, and did not differ in nonverbal intelligence. All children came from low income families and completed a range of measures tapping verbal and visuospatial working memory, selective attention, interference suppression and different domains of language (syntax and expressive and receptive vocabulary). Results indicate that despite large differences in their language scores (Bi-SLI < Bi-TD < Mo-TD), the groups exhibited comparable performance on the measures of visuospatial working memory, focused attention, and inhibitory suppression. Group differences emerged on the verbal working memory measures with Bi-SLI children performing significantly less well than the bilingual and monolingual typically developing groups that manifested comparable performance. The data suggests that: (a) children with SLI present verbal working memory limitations accompanied by preserved visuospatial executive functioning; (b) the measure that best discriminated the Bi-SLI group from their typically developing peers was the verbal working memory task digit recall. Practical implication for diagnosing SLI in bilingual children from disadvantaged social contexts will be discussed. [less ▲]

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See detailInstallation and First Evaluation of the King Edward Point Geodetic Observatory, South Georgia
Teferle, Felix Norman UL; White, Seth Warren; Foden, Peter R. et al

Poster (2013, May)

During February 2013 the King Edward Point (KEP) Geodetic Observatory was established in South Georgia through a University of Luxembourg funded research project in collaboration with the National ... [more ▼]

During February 2013 the King Edward Point (KEP) Geodetic Observatory was established in South Georgia through a University of Luxembourg funded research project in collaboration with the National Oceanography Centre and the British Antarctic Survey. Due to its remote location in the South Atlantic Ocean as well as being one of few subaerial exposures of the Scotia plate, South Georgia has been a key location for a number of global monitoring networks, e.g. seismic, magnetic and oceanic. However, no geodetic monitoring station had been established previously despite the global network of Global Navigation Satellite System (GNSS) stations is lacking observations from this region. In this presentation we will present a first evaluation of the observations from the KEP Geodetic Observatory for the period from 14 February to 14 April 2013. We calculate multipath characteristics and positioning statistics from precise point positioning (PPP) and discuss the installation in terms of benefits for studies of tectonics and glacio-isostatic adjustment processes. The meteorological data is evaluated by comparison to the data from the existing KEP meteorological station and a widely used numerical weather model. [less ▲]

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See detailROS-induced regulation of mitophagy and its failure in Parkinson’s disease
Kolodkin, Alexey UL; Ignatenko, Andrew UL; Simeonidis, Vangelis UL et al

Poster (2013, May)

Reactive Oxygen Species (ROS) generation is an unavoidable background process in the normal functioning of the cell. The greatest contributor to ROS production is the electron transport chain (ETC) where ... [more ▼]

Reactive Oxygen Species (ROS) generation is an unavoidable background process in the normal functioning of the cell. The greatest contributor to ROS production is the electron transport chain (ETC) where O2 is reduced to H2O. Some incompletely-reduced oxygen species escape and oxidize a variety of organic molecules (e.g. proteins and lipids in the mitochondrial membrane), leading to molecular dysfunction and initiating a positive feedback loop leading to generation of even more active radicals. Increased ROS concentration damages mitochondria and further increases ROS generation. Healthy cells manage ROS enzymatically with superoxide dismutase and other enzymes, various antioxidants, and ultimately through increased mitophagy of damaged mitochondria. The precise tuning of the latter mechanism is crucial for cell survival and is controlled in the cell by a ROS-induced regulatory network, which consists of many components such as Nrf2, Keap1, Parkin and p62 with a rather complicated cross-talk (Figure 1). In many diseases (cancer, Parkinson’s disease (PD), Huntington’s disease (HD), etc.), various components of the ROS management network are altered. Deconstructing the molecular mechanisms underlying or resulting from these alterations might contribute to better understanding of the dynamics of related pathophysiological processes. We have built a kinetics-based model which recapitulates the consensus understanding of the mechanism responsible for cellular ROS – managing system. [less ▲]

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See detailRécits de parents en situation vulnérable: Trajectoires de résilience familiale?
Dujardin, Céline UL; Ferring, Dieter UL

Poster (2013, May)

Dans la société actuelle, la famille est confrontée à plusieurs domaines d’action et politiques visant l’épanouissement familial et l’amélioration de la situation socio-économique et psycho-éducative ... [more ▼]

Dans la société actuelle, la famille est confrontée à plusieurs domaines d’action et politiques visant l’épanouissement familial et l’amélioration de la situation socio-économique et psycho-éducative, mais ceci en poursuivant différents objectifs à la fois. Dans ces domaines, nous retrouvons l’encouragement de l’emploi des femmes, la promotion de l’égalité des sexes, l’accueil de la petite enfance et l’école désirant entrer en partenariat éducatif, l’aide à l’enfance et à la famille proposant des soutiens à la parentalité etc. (cf. OCDE, 2011). Mais que vivent les parents bénéficiant d’une intervention socio-éducative quant à l’éducation des enfants ou quant aux difficultés intrafamiliales? L’étude qualitative communiquée se centre sur les récits de vie de parents en situation vulnérable dans le but de repérer leur élaboration de la notion de parentalité et d’éducation familiale. Plus spécifiquement, la recherche s’adresse aux difficultés rencontrées par les parents, aux réponses trouvées face aux difficultés parentales voire familiales, et aux trajectoires familiales contenant un développement favorable pour la famille. En outre, l'étude cherche à identifier des critères qualifiant les trajectoires familiales positives comme caractéristiques résilientes. Par ailleurs, nous examinons si le parent occupe un rôle central dans le processus de résilience familiale. Le raisonnement avec le concept de résilience familiale, c’est-à-dire la possibilité de trouver des résultats positifs préservant le développement de chaque membre et de l’unité familiale (Delage, 2010), nous permet de refléter les aspects favorables des trajectoires familiales, sans pour autant négliger les aspects vulnérables. [less ▲]

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See detailA Bayesian Monte Carlo Markov Chain Method for the Analysis of GPS Position Time Series
Olivares Pulido, German UL; Teferle, Felix Norman UL

Poster (2013, April 12)

Position time series from continuous GPS are an essential tool in many areas of the geosciences and are, for example, used to quantify long-term movements due to processes such as plate tectonics or ... [more ▼]

Position time series from continuous GPS are an essential tool in many areas of the geosciences and are, for example, used to quantify long-term movements due to processes such as plate tectonics or glacial isostatic adjustment. It is now widely established that the stochastic properties of the time series do not follow a random behavior and this affects parameter estimates and associated uncertainties. Consequently, a comprehensive knowledge of the stochastic character of the position time series is crucial in order to obtain realistic error bounds and for this a number of methods have already been applied successfully. We present a new Bayesian Monte Carlo Markov Chain (MCMC) method to simultaneously estimate the model and the stochastic parameters of the noise in GPS position time series. This method provides a sample of the likelihood function and thereby, using Monte Carlo integration, all parameters and their uncertainties are estimated simultaneously. One advantage of the MCMC method is that the computational time increases linearly with the number of parameters, hence being very suitable for dealing with a high number of parameters. A second advantage is that the properties of the estimator used in this method do not depend on the stationarity of the time series. At least on a theoretical level, no other estimator has been shown to have this feature. Furthermore, the MCMC method provides a means to detect multi-modality of the parameter estimates. We present an evaluation of the new MCMC method through comparison with widely used optimization and empirical methods for the analysis of GPS position time series. [less ▲]

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See detailLong-term mass changes over Greenland derived from high-low satellite-to-satellite tracking
Weigelt, Matthias UL; van Dam, Tonie UL; Jäggi, Adrian et al

Poster (2013, April)

In the last decade, temporal variations of the global gravity field have become an ubiquitous and invaluable source of information for geophysical and environmental studies. It is important that the time ... [more ▼]

In the last decade, temporal variations of the global gravity field have become an ubiquitous and invaluable source of information for geophysical and environmental studies. It is important that the time series of observations is not interrupted as some geophysical phenomena, e.g. postglacial rebound or long term ice mass trends, are only beginning to be observable. To date, the most valuable source for time variable gravity (TVG) is the GRACE mission which has already exceeded its nominal lifetime. It can cease operations any time now and then only high-low satellite-to-satellite (hl-SST) observations will be available. These observations have, however, only demonstrated limited application for TVG. In this presentation, we show that by using CHAMP data, a thorough reprocessing strategy and a dedicated Kalman filter it is possible to derive the very long wavelength features of the time variable gravity field. The results are validated against GRACE data and height coordinates from long-term GPS ground stations in Greenland. We find that the quality of the CHAMP solutions is sufficient to derive realistic long-term trends and annual amplitudes of mass changes of Greenland. We conclude that hl-SST would be a viable substitute (although at lower spatial resolution) for TVG in the event of a profund operational breakdown of GRACE. [less ▲]

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See detailThe influence of language on exact additions in bilingual adults.
Van Rinsveld, Amandine UL; Brunner, Martin UL; Landerl, Karin et al

Poster (2013, April)

To which degree is language involved in arithmetic? We investigated this question in a German-French bilingual setting. In Luxembourg, bilingualism is acquired through education: mathematics are taught in ... [more ▼]

To which degree is language involved in arithmetic? We investigated this question in a German-French bilingual setting. In Luxembourg, bilingualism is acquired through education: mathematics are taught in German in primary and in French in secondary school. Interestingly, the decades and units within two-digit number names follow the unit-decade order in German but the decade-unit order in French. Forty-eight bilingual adults performed simple and complex additions. Participants had to orally respond either in German or in French. Additions were presented in different conditions: (1) visual Arabic presentation, (2) auditory presentation (in German or in French), and (3) as a dual task in which visually presented additions were preceded by visually presented semantic judgments to indirectly activate a German or French language context. The results showed that participants performed complex calculations better in the dominant language (German), while there were no differences for simple calculations. Thus, language proficiency seems to be crucial for the computation of more complex calculations, whereas arithmetic facts can be retrieved equally well in both languages. Further, adding language at the input level (auditory presentation) enhanced performances for simple calculations, especially in the non-dominant language (French), while it was exactly the opposite effect for complex calculations. Additionally, visual additions were better performed within a surrounding linguistic context (3) than alone (1) in their non-dominant language, suggesting the crucial role of the linguistic context of an addition task in bilinguals. Taken together, these results support the view of a strong language impact on calculations. [less ▲]

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See detailActualités récentes: Abus de marché, Mifid, UCITS et Prospectus
Conac, Pierre-Henri UL

Poster (2013, March 22)

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See detailThe Parkinson's Disease Map: A Framework for Integration, Curation and Exploration of Disease-related Pathways
Ostaszewski, Marek UL; Fujita, Kazuhiro; Matsuoka, Yukiko et al

Poster (2013, March 09)

Objectives: The pathogenesis of Parkinson's Disease (PD) is multi-factorial and age-related, implicating various genetic and environmental factors. It becomes increasingly important to develop new ... [more ▼]

Objectives: The pathogenesis of Parkinson's Disease (PD) is multi-factorial and age-related, implicating various genetic and environmental factors. It becomes increasingly important to develop new approaches to organize and explore the exploding knowledge of this field. Methods: The published knowledge on pathways implicated in PD, such as synaptic and mitochondrial dysfunction, alpha-synuclein pathobiology, failure of protein degradation systems and neuroinflammation has been organized and represented using CellDesigner. This repository has been linked to a framework of bioinformatics tools including text mining, database annotation, large-scale data integration and network analysis. The interface for online curation of the repository has been established using Payao tool. Results: We present the PD map, a computer-based knowledge repository, which includes molecular mechanisms of PD in a visually structured and standardized way. A bioinformatics framework that facilitates in-depth knowledge exploration, extraction and curation supports the map. We discuss the insights gained from PD map-driven text mining of a corpus of over 50 thousands full text PD-related papers, integration and visualization of gene expression in post mortem brain tissue of PD patients with the map, as well as results of network analysis. Conclusions: The knowledge repository of disease-related mechanisms provides a global insight into relationships between different pathways and allows considering a given pathology in a broad context. Enrichment with available text and bioinformatics databases as well as integration of experimental data supports better understanding of complex mechanisms of PD and formulation of novel research hypotheses. [less ▲]

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See detailThe impact of inhibition capacities on number-space associations
Hoffmann, Danielle UL; Pigat, Delia; Schiltz, Christine UL

Poster (2013, March 01)

Numerical and spatial representations are tightly linked (for a review see de Hevia et al., 2008). One specific instance of this link is the finding that when doing a binary classification judgment on ... [more ▼]

Numerical and spatial representations are tightly linked (for a review see de Hevia et al., 2008). One specific instance of this link is the finding that when doing a binary classification judgment on single Arabic digits, participants are faster to respond with their left/right hand to small/large numbers respectively. This observation has first been described by Dehaene and colleagues in the early 1990’s (Dehaene et al., 1993) and termed the SNARC effect (Spatial Numerical Association of Response Codes). Celebrating its 20th anniversary this year, the SNARC effect has been extensively replicated (for a meta-analysis see Wood et al., 2008) but one of its characteristics remains its high inter-individual variability (Wood et al., 2006a; 2006b). The source of this variability can partly be ascribed to differences in mathematical proficiency (Hoffmann et al., submitted) but a more domain general hypothesis implicating general inhibition capacities warrants further investigation. For the present study a total of 77 participants have been evaluated with a SNARC paradigm as well as standard inhibition tests (Stroop, Incompatibility subtest of the TAP test). Results show that when age-appropriate inhibition tests are used, inhibition capacities are strongly correlated with the SNARC effect, in the way that very efficient inhibition capacities lead to weaker SNARC effects. Consequently this finding could at least partly explain the impact of arithmetical proficiency on the SNARC effect. A study combining both measures would be an appropriate next step. [less ▲]

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See detailEstimation abilities of large numerosities in preschool children: Do they depend on school grade and socio-economic background?
Mejias, Sandrine; Schiltz, Christine UL

Poster (2013, March 01)

The approximate number system (ANS) is thought to be a building block for the elaboration of formal mathematics. However, little is known about how this core system develops and if it can be influenced by ... [more ▼]

The approximate number system (ANS) is thought to be a building block for the elaboration of formal mathematics. However, little is known about how this core system develops and if it can be influenced by external factors at a young age (before the child enters formal numeracy education). The purpose of this study was to examine numerical magnitude representations of 5-6 year old children at 2 different moments of Kindergarten considering children's early number competence as well as schools' socio-economic index (SEI). This study investigated estimation abilities of large numerosities using symbolic and non-symbolic output formats (8-64). In addition, we assessed symbolic and non-symbolic early number competence (1-12) at the end of the 2nd (N = 42) and the 3rd (N = 32) Kindergarten grade. By letting children freely produce estimates we observed surprising estimation abilities at a very young age (from 5 year on) extending far beyond children's symbolic explicit knowledge. Moreover, the time of testing has an impact on the ANS accuracy since 3rd Kindergarteners were more precise in both estimation tasks. Additionally, children who presented better exact symbolic knowledge were also those with the most refined ANS. However, this was true only for 3rd Kindergarteners who were a few months from receiving math instructions. In a similar vein, higher SEI positively impacted only the oldest children's estimation abilities whereas it played a role for exact early number competences already in 2nd and 3rd graders. Our results support the view that approximate numerical representations are linked to exact number competence in young children before the start of formal math education and might thus serve as building blocks for mathematical knowledge. Since this core number system was also sensitive to external components such as the SEI this implies that it can most probably be targeted and refined through specific educational strategies from preschool on. [less ▲]

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See detailNanoscale confinement of a low molecular weight liquid
Djemour, Anna UL; Baller, Jörg UL; Di Giambattista, Carlo UL et al

Poster (2013, March)

Detailed reference viewed: 39 (6 UL)
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See detailThe influence of language on exact additions in bilingual pupils and adults.
Van Rinsveld, Amandine UL; Brunner, Martin UL; Landerl, Karin et al

Poster (2013, March)

To which degree is language involved in arithmetic? We investigated this question in a German-French bilingual setting. In Luxembourg, bilingualism is acquired through education: mathematics are taught in ... [more ▼]

To which degree is language involved in arithmetic? We investigated this question in a German-French bilingual setting. In Luxembourg, bilingualism is acquired through education: mathematics are taught in German in primary and in French in secondary school. Interestingly, the decades and units within two-digit number names follow the unit-decade order in German but the decade-unit order in French. We studied our research question in the multi-lingual educational context of Luxembourg by applying a developmental design. The present sample (total N = 200) included students from grades 7, 8, 10 and 11, as well as an adult bilingual group. This sample takes advantage of following the progressive transition from German to French as teaching languages. All participants performed simple and complex additions that they had to orally respond either in German or in French. Additions were presented in different conditions: (1) visual Arabic presentation, (2) auditory presentation (in German or in French), and (3) as a dual task in which visually presented additions were preceded by visually presented semantic judgements to indirectly activate a German or French language context. The results suggested that language proficiency seems to be crucial for the computation of more complex calculations, whereas simple additions can be retrieved equally well in both languages. Taken together, these results support the view of a strong language impact on calculations. Further results and implications will be discussed. [less ▲]

Detailed reference viewed: 94 (7 UL)
See detailThermal and mechanical properties of styrene butadiene rubber/alumina nanocomposites
Sushko, Rymma UL; Baller, Jörg UL; Sanctuary, Roland UL

Poster (2013, March)

SBR is a rubber material with high technical relevance. In order to enhance the mechanical properties of the rubber one method consists e. g. in dispersing inorganic nanoparticles in the polymer matrix ... [more ▼]

SBR is a rubber material with high technical relevance. In order to enhance the mechanical properties of the rubber one method consists e. g. in dispersing inorganic nanoparticles in the polymer matrix. By doing so, the properties of a given composite can be tuned either by changing the nanoparticle concentration or by modifying the surface properties of the fillers. Both interventions have indeed the potential to take influence on the structure and properties of the interphases emerging between the fillers and the polymer matrix. In this contribution we report on the glass transition behavior of SBR/alumina nanocomposites when the concentration and surface properties of the Al2O3 nanoparticles are changed. We also discuss the influence of the fillers on the shear stiffness of the rubber material. The samples were investigated by temperature modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA). TMDSC investigations shed light on a surprising behavior of the glass transition temperature when the nanoparticle concentration is changed: at low filler contents the quasi-static glass transition temperature Tg passes through a minimum. While further increasing the nanoparticle content Tg increases to finally saturate at high concentrations. One of the main DMA results is that increasing of the Al2O3 concentration induces a quasi-solid-like frequency-independent response of the nanocomposites in the low frequency regime. [less ▲]

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See detailPromoting the construction of alternative representations in arithmetic problem solving with 4th and 5th grade pupils
Gamo, Sylvie UL; Nogry, Sandra; Sander, Emmanuel

Poster (2013, March)

The underlying assumption was that the nature of the variable involved in an arithmetical problem in which there are several solving strategies influences the construction of the representation and might ... [more ▼]

The underlying assumption was that the nature of the variable involved in an arithmetical problem in which there are several solving strategies influences the construction of the representation and might force the strategy used, hiding the possibilities to become aware of others (Gamo, Taabane & sander, 2011). This study intended to lead pupils to build an alternative representation than those spontaneously induced by the statement. It investigated the role of training of semantic recoding based on an analogy between the problems and a comparison of strategies to facilitate transfer of problem-solving strategies in problems sharing the same formal mathematical structure but differing in semantic representation [less ▲]

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See detailThe impact of inhibition capacities on number-space associations in young and elderly adults
Hoffmann, Danielle UL; Pigat, Delia; Schiltz, Christine UL

Poster (2013, February 26)

Background: Numerical and spatial representations are tightly linked, i.e. when doing a binary classification judgment on Arabic digits participants are faster to respond with their left/right hand to ... [more ▼]

Background: Numerical and spatial representations are tightly linked, i.e. when doing a binary classification judgment on Arabic digits participants are faster to respond with their left/right hand to small/large numbers respectively (SNARC effect, Dehaene et al., 1993). The SNARC effect has been extensively replicated but one of its characteristics remains inter-individual variability (Wood et al., 2006). Different sources have been proposed to account for the reported inter-individual variability, namely response speed (Gevers et al., 2006), inhibition capacities (Wood et al., 2008) and age (Wood et al., 2008). The present study aims to investigate the impact of inhibition capacities on the SNARC effect in young and elderly adults, controlling for individual general processing speed. Methods: Two groups of participants were included: young adults, N=28, mean age: 23 years (SD=3.02) and elderly adults, N=46, mean age: 65.9 years (SD=3.9). Participants performed a parity judgment SNARC paradigm as well as inhibition tests (Stroop, Incompatibility). General processing speed was evaluated using a simple shape matching task. Results: The two age-groups differed in the strength of the SNARC effect, inhibition capacities and processing speed, with the elderly adults displaying stronger SNARC effects, weaker inhibition capacities and slower processing speed. Correlation analysis including all participants confirmed these findings on an individual level by showing relations between the SNARC effect and age, as well as relations between the SNARC effect and both inhibition capacities (i.e. the Stroop effect) and processing speed. When controlling for processing speed, the relations between the SNARC effect and both inhibition capacities and age remained. Conversely, when controlling for inhibition capacities, only the relation between the SNARC effect and age (but not processing speed) remained significant, even when controlling in addition for processing speed. Relevance: By combining the variables age, inhibition capacities and individual processing speed, the present data are the first to reveal a strong link between inhibition capacities and number-space associations. Importantly, we demonstrate that this link is not mediated by general processing speed. Interestingly, the robust relation between the SNARC effect and age remains after controlling for processing speed and inhibition capacities, pointing to a new source of inter-individual differences in the strength of the SNARC effect that will need to be clarified in future research projects. [less ▲]

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See detailModeling default correlation in a US retail loan portfolio
Pisa, Magdalena UL

Poster (2013)

Detailed reference viewed: 37 (6 UL)
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See detailRipple effects from industry defaults
Pisa, Magdalena UL

Poster (2013)

Detailed reference viewed: 52 (14 UL)
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See detailEffects of state aggregation in duration analysis
Hartung, Anne UL

Poster (2013)

Detailed reference viewed: 48 (0 UL)
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See detailDynamic modeling of VISSIM critical gap parameter at unsignalized intersections
Viti, Francesco UL; Wolput, Bart; Tampere, Chris M.J. et al

Poster (2013)

Detailed reference viewed: 72 (0 UL)
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See detailThe Good, The Bad, and The Oxytocin: context-specific facilitation of helping.
Schaan, Violetta UL; Reilly, Katherine; Hawley, Kathryn et al

Poster (2013)

Evidence suggests that oxytocin might facilitate helping behavior. Participants (N =122) were tested in a double-blind randomized placebo-controlled trial with intranasal oxytocin. Helping behavior was 1 ... [more ▼]

Evidence suggests that oxytocin might facilitate helping behavior. Participants (N =122) were tested in a double-blind randomized placebo-controlled trial with intranasal oxytocin. Helping behavior was 1) shaped by stimulus valence, 2) triggered by social stimuli and 3) sensitive to social group (animals vs. humans). [less ▲]

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See detailPOSTER: Critique of the CISSP Common Body of Knowledge of Cryptography
Neuhaus, Stephan; Gheorghe, Gabriela UL

Poster (2013)

Detailed reference viewed: 146 (6 UL)
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See detailComplex Dynamics in Random DNA Strand Circuits
Banda, Peter UL; Teuscher, Christof

Poster (2013)

Detailed reference viewed: 65 (0 UL)
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See detailThe use of the minus sign in solving arithmetical equations
Vlassis, Joëlle UL

Poster (2013)

Detailed reference viewed: 59 (5 UL)
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See detailNanoscale Characterization of Amine-Epoxy Interphase in 3D Confinement network (porous glass)
Filimon, Marlena UL; Schmauch, Jörg; Sanctuary, Roland UL

Poster (2013)

Many aspects of polymer research and application are directly connected with surface and interface phenomena occurring when polymers are brought into contact with substrates made of another kind of ... [more ▼]

Many aspects of polymer research and application are directly connected with surface and interface phenomena occurring when polymers are brought into contact with substrates made of another kind of material (e.g. metals, nanoparticles, etc.). Generally, interphases emerge between polymer matrix and substrate. These are regions with morphologies and properties differing from those of polymer and substrate. While curing a thermoset, at least two different types of monomers react to form a high molecular weight polymer network. The composition of the mixture of reactance can be altered near substrate in contact with thermoset components. In this poster, we present some preliminary results obtained for interphases which appear while curing an amine-epoxy thermoset in contact with a porous glass (pore size ~20 nm). As tools for investigating the interphases, we exploited Scanning Electron Microscopy (SEM) in addition with Energy-Dispersive X-ray Spectroscopy (EDS) and Tapping-Mode Atomic Force Microscopy (TM - AFM). [less ▲]

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See detailHow the human brain discriminates numerosities: A steady-state visual-evoked potentials study
Mejias, Sandrine; Rossion, Bruno; Schiltz, Christine UL

Poster (2013)

This study aimed at measuring rapidly and objectively human adults' sensitivity to (non)symbolic numerical stimuli, using the steady-state visual-evoked potentials (1) response in the context of ... [more ▼]

This study aimed at measuring rapidly and objectively human adults' sensitivity to (non)symbolic numerical stimuli, using the steady-state visual-evoked potentials (1) response in the context of repetition suppression (2). It aimed to demonstrate the feasibility of the method and evaluate its potential to tap into the basic numerical representation systems that can be assumed to underlie symbolic and non-symbolic magnitude comparisons. Following a short duration experiment, we observed a large reduction of signal specifically at the 3.5 Hz response, over the occipito-temporo-parietal cortex. This reduction was greater for symbolic than non-symbolic control stimuli. This first observation of repetition suppression to fast periodic stimulation of symbolic and non-symbolic numerosities in the human brain offers a promising tool to study the sensitivity to numerosities in the human brain in adults, but also especially in children. [less ▲]

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See detailSex-related effects of oxytocin on interpersonal closeness and emotional accuracy.
Hawley, Kathryn; Reilly, Katherine; Schaan, Violetta UL et al

Poster (2013)

The effects of oxytocin might be sexual dimorphic. Male and female participants (N=122; 49% females) were tested using intranasal spray in a double-blind randomized, OT vs. placebo-controlled trial. OT ... [more ▼]

The effects of oxytocin might be sexual dimorphic. Male and female participants (N=122; 49% females) were tested using intranasal spray in a double-blind randomized, OT vs. placebo-controlled trial. OT-men reported an increase in interpersonal closeness and higher emotional accuracy relative to OT-women; placebo conditions did not yield sex differences. [less ▲]

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See detailGrowth kinetics of solid-liquid interface
Turci, Francesco UL; Schilling, Tanja UL; Oettel, Martin

Poster (2013)

Detailed reference viewed: 73 (5 UL)
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See detailCardiac vagal tone moderates the effect of oxytocin on social perception.
Reilly, Katherine; Hawley, Kathryn; Schaan, Violetta UL et al

Poster (2013)

We measured participants’ cardiac vagal tone and administered oxytocin or a placebo before participants completed a task assessing person perception accuracy. There was a significant interaction between ... [more ▼]

We measured participants’ cardiac vagal tone and administered oxytocin or a placebo before participants completed a task assessing person perception accuracy. There was a significant interaction between vagal tone and drug condition. These results provide support for the hypothesis that vagal tone moderates oxytocin’s effects on social perception. [less ▲]

Detailed reference viewed: 78 (2 UL)
See detailSystematic molecular measurements reveal key microbial populations driving community-wide phenotype
Muller, Emilie UL; Pinel, Nicolás; May, Patrick UL et al

Poster (2013)

Natural microbial communities are heterogeneous and dynamic. Therefore, a major consideration for multiple omic data studies is the sample-to-sample heterogeneity, which can lead to inconsistent results ... [more ▼]

Natural microbial communities are heterogeneous and dynamic. Therefore, a major consideration for multiple omic data studies is the sample-to-sample heterogeneity, which can lead to inconsistent results if the different biomolecular fractions are obtained from distinct sub-samples. Conversely, systematic omic measurements, i.e. the standardised, reproducible and simultaneous measurement of multiple features from a single undivided sample, result in fully integrable datasets. Objective In order to prove the feasibility and benefits of such systematic measurements in the study of the respective contributions of different populations to the community-wide phenotype, we purified and analysed all biomolecular fractions, i.e. DNA, RNA, proteins and metabolites, obtained from a unique undivided sample of lipid accumulating microbial community (LAMC) from wastewater treatment plant and integrate the resulting datasets. Methods One time point of particular interest was first selected out of 4 LAMC samples for its high diversity and strong lipid accumulation phenotype. Then, the systematic measurement strategy was applied to the selected undivided LAMC sample and the purified biomolecules were analysed by high-throughput techniques. DNA and RNA sequencing reads were assembled at the population-level using different binning strategies. A database, containing predicted proteins, was constructed to identify the detected peptides. Finally, all biomolecular information was mapped onto the assembled composite genomes to identify the precise roles of the different populations in the community-wide lipid accumulation phenotype. Results Metabolomics and 16S diversity analyses were used to select the sample of highest interest for detailed analysis. The systematic measurements of the selected sample followed by data integration have allowed us to probe the functional relevance of the population-level composite genomes, leading to the identification of the LAMC key players. Conclusion As community phenotype is not the sum of the different partner phenotypes, understanding a microbial community system requires more than the study of isolated organisms. Even if both approaches are complementary, top-down systematic approached only provides a holistic perspective of micro-ecological processes. [less ▲]

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See detailDifferentiated SH-SY5Y Cells as PD Model for Mitochondrial Dysfunction: From Whole Genome Sequencing to an Educated Design of High-Throughput Experiments
Antony, Paul UL; Krishna, Abhimanyu UL; May, Patrick UL et al

Poster (2013)

Objectives: Mitochondrial dysfunction is a cellular hallmark of Parkinson's disease (PD) and energetic stress of dopaminergic neurons appears to be a physiological risk factor for mitochondrial ... [more ▼]

Objectives: Mitochondrial dysfunction is a cellular hallmark of Parkinson's disease (PD) and energetic stress of dopaminergic neurons appears to be a physiological risk factor for mitochondrial dysfunction. It is however challenging to assess the high variety of factors regulating mitochondrial physiology in living neurons in a high throughput manner. To overcome this bottleneck, we established an analysis platform, using the neuroblastoma cell line SH-SY5Y. For the first time ever we have characterized the SH-SY5Y cell line in an integrated whole genome, transcriptome, and proteome approach. In addition, we show that neuronal differentiation improves the physiological properties of this experimental model for studying mitochondrial dysfunction in PD. Methods: Whole genome sequencing, RNA-Seq, qRT-PCR, MS, FRET using Voltage sensing proteins, Immunofluorescence, cytometry, and live cell imaging. Results: The integrated molecular characterization of SH-SY5Y uncovers the level of molecular network integrity and hence the relevance of this cell line for targeted studies in selected molecular processes. Furthermore, we dissect changes in mitochondrial and energetic stress factors during the process of neuronal differentiation. Conclusions: In terms of both morphology and energetic stress response, differentiated SH-SY5Y cells are more similar to dopaminergic neurons than their undifferentiated precursors. Thanks to dividing progenitors and the short duration of differentiation, combined with the use of specific endpoints analysed with high-content microscopy, our platform paves the route for high throughput experiments on a neuronal cell culture model for PD. Our genomic characterization and expression profiling of SH-SY5Y cells furthermore helps guiding the experimental design and interpretation of such studies. [less ▲]

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See detailNeural correlates of the acquisition of a motor expertise with extended practice: A fMRI study
Borragan Pedraz, Guillermo; Guillaume, Mathieu UL; Atas, Anne et al

Poster (2013)

Detailed reference viewed: 91 (1 UL)
See detailEco-systems biology of microbial communities: integration of biomolecular information from unique samples
Muller, Emilie UL; Roume, Hugo UL; Wilmes, Paul UL

Poster (2013)

In microbial ecology, high-resolution molecular approaches are essential to characterize the vast organismal and functional diversity and to understand the interactions between environmental factors and ... [more ▼]

In microbial ecology, high-resolution molecular approaches are essential to characterize the vast organismal and functional diversity and to understand the interactions between environmental factors and microbial communities (MCs). Molecular eco-systems biology based on the integration of genomics and functional omics, allows conclusive links to be drawn between genetic potential and function. However, the field faced major challenges arising from the heterogeneity and dynamics of MCs. Hence, to facilitate meaningful data integration, analysis and modeling, it is crucial to obtain standardised, reproducible and simultaneous measurements of multiple features from a unique sample. We have developed a new methodological framework for the isolation of high-quality DNA, large and small RNA, proteins and metabolites fractions from undivided MC samples. The methodology is based on cryogenic sample preservation and cell lysis. Metabolites are first extracted using organic solvents, followed by sequential isolation of biomacromolecules using chromatographic spin column technology. The methodology was validated by comparison to commonly used dedicated methods and its broad applicability was demonstrated on MCs of biotechnological, environmental and medical interest. Applying this method to sewage plant MCs has allowed us to determine community-level keystone genes and to probe the functional relevance of the population-level composite genomes, leading to the identification of key players of the community. This methodological framework lays the foundation for standardized molecular eco-systems biology and offers exciting prospects for elucidating the genetic blueprints and the functional relevance of specific populations within MCs, particularly in relation to environment-driven demography changes leading to catastrophic bifurcations. [less ▲]

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See detailThe SNARC effect and its relationship to spatial abilities in women
Georges, Carrie UL; Hoffmann, Danielle UL; Schiltz, Christine UL

Poster (2013)

A classical demonstration of number-space associations is the so-called SNARC (Spatial Numerical Association of Response Codes) effect. It consists in faster reaction times to small/large digits with the ... [more ▼]

A classical demonstration of number-space associations is the so-called SNARC (Spatial Numerical Association of Response Codes) effect. It consists in faster reaction times to small/large digits with the left/right hand respectively. To get a better understanding of the well-documented inter-individual variability in the SNARC effect, we investigated the relationship between the classically used parity SNARC and spatial abilities, as indexed by visuo-spatial working memory capacity (WMC). The study population consisted of female university students (n=20; mean age=23.79; SD=2.50) recruited in the fields of humanities and educational sciences. Since systematic studies on the reliability of the SNARC effect are still lacking, we first measured the internal consistency, as assessed by split-half reliability, as well as test-retest reliability of the parity SNARC. Split-half and test-retest correlation coefficients were (r(19)=0.41; p<0.05) and (r(19)=0.25; p=0.14) respectively, indicating a trend towards consistency. In the present female population, a significant negative correlation was revealed between the strength of the parity SNARC effect (mean slope=-10.04; SD=8.66) and visuo-spatial WMC (mean WMC=2.85; SD=1.12; r(19)=-0.51; p<0.05). This finding thus indicates that number-space associations as measured by the parity SNARC effect tend to be stronger in young female adults with higher spatial abilities. [less ▲]

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See detailPOSTER: Preserving Privacy and Accountability for Personal Devices
Gheorghe, Gabriela UL; Neuhaus, Stephan

Poster (2013)

Detailed reference viewed: 139 (13 UL)
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See detailProcedural and magnitude-based strategies in solving complex additions: Insights from fMRI
Guillaume, Mathieu UL; Peigneux, Philippe; Borragan Pedraz, Guillermo et al

Poster (2013)

Detailed reference viewed: 42 (1 UL)
See detailA model microbial community for Eco-Systems Biology
Muller, Emilie UL; Roume, Hugo UL; Buschart, Anna UL et al

Poster (2013)

Objective Microbial communities (MCs) play crucial roles in human health and disease. In-depth characterization of the vast organismal and functional diversity of MCs is now facilitated by high-resolution ... [more ▼]

Objective Microbial communities (MCs) play crucial roles in human health and disease. In-depth characterization of the vast organismal and functional diversity of MCs is now facilitated by high-resolution molecular approaches. Systematic measurements are key for meaningful data integration, analysis and modeling. Based on a model MC from a biological wastewater treatment plant, we have developed a new framework based on wet- and dry-lab methods for the integrated analyses of MCs at the population- as well as at the community-level. Methods The overall methodological framework first relies on a standardised wet-lab procedure for the isolation of concomitant biomolecules, i.e., DNA, RNA, proteins and metabolites, from single undivided samples. Purified biomolecular fractions then are subjected to high-resolution omic analyses including metagenomics, metatranscriptomics, metaproteomics and (meta-) metabolomics. The resulting data form the input for integrated bioinformatic analyses. Population-level integrated omic analyses rely on a newly developed binning and re-assembly method, which yields near-complete genome reconstructions for dominant populations. Community-level analyses involve the reconstruction of community-wide metabolic networks. Functional omic data is then mapped onto these reconstructions and contextualized. Results Application of the population-centric workflow has allowed us to reconstruct and identify 10 major populations within the model MC and has led to the identification of a key generalist population, Candidatus Microthrix spp., within the community. Analysis of the community-wide metabolic networks has allowed the identification of keystone genes involved in lipid and nitrogen metabolism within the MC. Conclusions Our new methodological framework offers exciting new prospects for elucidating the functional relevance of specific populations and genes within MCs. The established workflows are now being applied to samples of biomedical research interest such as human gastrointestinal tract-derived samples. [less ▲]

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See detailLinking mixed microbial community phenotype to individual genotypes
Muller, Emilie UL; Pinel, Nicolás; May, Patrick UL et al

Poster (2013)

Biological wastewater treatment is arguably the most widely used biotechnological process on Earth. Wastewater also represents a valuable energy commodity that is currently not being harnessed ... [more ▼]

Biological wastewater treatment is arguably the most widely used biotechnological process on Earth. Wastewater also represents a valuable energy commodity that is currently not being harnessed comprehensively. Mixed microbial communities that naturally occur at the air-water interface of certain biological wastewater treatment systems accumulate excess long chain fatty acids intracellularly. This phenotypic trait may potentially be exploited for the transformation of lipid-rich wastewater into biodiesel (fatty acid methyl esters). Using a molecular Eco-Systems Biology approach, we are studying which genes contribute to the lipid accumulation phenotype and, thus, overall community function. We first compared the lipid accumulation phenotype to the structure of lipid accumulating communities from a local wastewater treatment plant by coupled deep sequencing of the 16S rRNA locus, metagenome sequencing and metabolomic analysis of 4 biological replicates sampled at 4 different time points. Based on the results of these analyses and in order to obtain a detailed view of the structure and function of the respective microbial communities, metagenomic, metatranscriptomic, metaproteomic and (meta-)metabolomic analyses were completed for a single representative biological sample of highest interest. In order to facilitate meaningful data integration of this highly heterogeneous consortium, biomolecular fractions used for the omic analyses were extracted from a unique single sample using a recently developed biomolecular isolation protocol. The coupled survey and the comparative metagenomic analysis demonstrate that the communities change significantly from dates with warm water temperatures to cold water temperatures while alpha diversity remains stable. In the winter period, this switch results in a strong enrichment of a bacterial genus well known to accumulate intracellular lipids, namely Microthrix spp., a representative genome of which has recently been sequenced by us. Correlation networks based on microorganism and concomitant intra- and extra-cellular metabolite abundances provides an overview of organisms potentially involved in the community-wide lipid accumulating phenotype. A sample with the highest abundance of Microthrix spp. was subsequently chosen for the construction of a community-wide metabolic model using metagenomic, metatranscriptomic, metaproteomic and (meta-)metabolomics data. Based on these omic datasets, expressed enzyme variants linked to the lipid accumulation phenotype have been identified and are currently undergoing in vitro characterization. Meta-omic analyses offer exciting prospects for elucidating the genetic blueprints and the functional relevance of specific populations within microbial communities. Consequently, connecting the overall community phenotype to specific genotypes will allow much needed fundamental ecological understanding of microbial community and population dynamics, particularly in relation to environment-driven demography changes leading to tipping points and catastrophic bifurcations. [less ▲]

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See detailOnTheFly 2.0: a tool for automatic annotation of files and biological information extraction.
Pafilis, Evangelos; Pavlopoulos, Georgios; Satagopam, Venkata UL et al

Poster (2013)

Retrieving all of the necessary information from databases about bioentities mentioned in an article is not a trivial or an easy task. Following the daily literature about a specific biological topic and ... [more ▼]

Retrieving all of the necessary information from databases about bioentities mentioned in an article is not a trivial or an easy task. Following the daily literature about a specific biological topic and collecting all the necessary information about the bioentities mentioned in the literature manually is tedious and time consuming. OnTheFly 2.0 is a web application mainly designed for non-computer experts which aims to automate data collection and knowledge extraction from biological literature in a user friendly and efficient way. OnTheFly 2.0 is able to extract bioentities from individual articles such as text, Microsoft Word, Excel and PDF files. With a simple drag-and-drop motion, the text of a document is extensively parsed for bioentities such as protein/gene names and chemical compound names. Utilizing high quality data integration platforms, OnTheFly allows the generation of informative summaries, interaction networks and at-a-glance popup windows containing knowledge related to the bioentities found in documents. OnTheFly 2.0 provides a concise application to automate the extraction of bioentities hidden in various documents and is offered as a web based application. [less ▲]

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See detailAn Evaluation of Real-Time Zenith Total Delay Estimates
Ahmed, Furqan UL; Teferle, Felix Norman UL; Bingley, Richard

Poster (2012, December)

Detailed reference viewed: 59 (3 UL)
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See detailWork Context and Career Development
Pignault, Anne UL; Houssemand, Claude UL

Poster (2012, November)

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See detailOn the capability of SWARM for estimating time-variable gravity fields and mass variations
Reubelt, T.; Baur, O.; Weigelt, Matthias UL et al

Poster (2012, October)

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See detailEmpathic responsiveness of different participant roles in bullying and cyber bullying
Steffgen, Georges UL; Tintorri, L.; Happ, Christian UL et al

Poster (2012, October)

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See detailEfeitos de contextos ambientais desfavoráveis na memória operacional
Engel de Abreu, Pascale UL; Puglisi, M; Cruz-Santos, A et al

Poster (2012, October)

Há um crescente número de estudos indicando que o desempenho em tarefas de memória operacional (MO) depende fortemente do conhecimento e experiência prévios. Poucos estudos, entretanto, têm explorado ... [more ▼]

Há um crescente número de estudos indicando que o desempenho em tarefas de memória operacional (MO) depende fortemente do conhecimento e experiência prévios. Poucos estudos, entretanto, têm explorado diretamente o papel do ambiente social no desenvolvimento de habilidades de MO.Este estudo teve como objetivo investigar o impacto da experiência escolar e linguística do indivíduo em tarefas de MO verbal e visual. [less ▲]

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See detailThe interaction between number and space processing and math achievement in adults
Hoffmann, Danielle UL; Mussolin, Christophe; Schiltz, Christine UL

Poster (2012, September 07)

Behavioral studies show a relation between numbers and space (for a review see De Hevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect ... [more ▼]

Behavioral studies show a relation between numbers and space (for a review see De Hevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect, consisting in faster reaction times responding to small/large digits with the left/right hand respectively (Dehaene et al. 1993). The SNARC effect has often been replicated, but it is also characterized by high inter-subject variability (Wood et al. 2006 a,b). Although differences in mathematical skills are an obvious candidate source for SNARC variability, this variable has not yet been explored systematically. For the present study, three groups of participants were recruited amongst University students; one group included only participants reporting specific problems related to numerical processing, and two control groups differing in the math requirements of their field of study (i.e. science students vs. literature students). Results confirmed that the three groups differed substantially in basic arithmetic scores [F(2,92)=19.97, p<0.001] as well as in the strength of their SNARC effect [F(2,92)=7.12, p=0.001]. The science group had the highest arithmetic score and the smallest SNARC effect and the problem report group had the lowest arithmetic score and the strongest SNARC effect, with the literature group lying in between. Rearranging the groups based on arithmetic performance yielded the same results. Correlation analyses confirmed this finding by revealing a strong relation between arithmetic scores and SNARC effect independently of group constitution [r=-0.28, p<0.01]. Different hypotheses in the context of the relevant literature are discussed. [less ▲]

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See detailA kinetic model and design principles study of cellular ROS defence and its failure in Parkinson’s disease
Kolodkin, Alexey UL; Simeonidis, Vangelis UL; Brady, Nathan et al

Poster (2012, August)

Mitochondrial generation of reactive oxygen species (ROS) is an unavoidable side effect of oxidative phosphorylation. To counteract the production of ROS, the cell employs two main strategies. The first ... [more ▼]

Mitochondrial generation of reactive oxygen species (ROS) is an unavoidable side effect of oxidative phosphorylation. To counteract the production of ROS, the cell employs two main strategies. The first one is to increase the consumption of ROS; this mechanism involves the superoxide dismutase enzyme and various antioxidants. The second strategy is to reduce the production of ROS by decreasing mitochondrial membrane potential and by increasing mitophagy. The precise tuning of the latter is crucial for cell survival: if mitophagy is too active, all mitochondria are lost and the cell suffers from reduced ATP capacity; if mitophagy is not active enough, dysfunctional mitochondria accumulate, more ROS is produced, and the cell undergoes unwanted programmed cell death. We hypothesize that a ROS-activated regulatory network is employed to coordinate the regulation of the rate of mitophagy, the expression of uncoupling proteins and the production of antioxidants, including SOD. In Parkinson’s disease (PD), the activities of several components of this regulatory network (e.g. KEAP1, PARK7, VDAC1, SQSTM1) are altered. This makes the cell susceptible to ROS damage. In the case of dopaminergic neurons, this effect can be particularly severe, because an additional pool of non-mitochondrial ROS generated during ROS-induced degradation of dopamine. In order to understand the functioning of the ROS-activated regulatory network in normal function and disease, we have built a kinetic model. Our model includes 39 species and 45 reactions, with 56 kinetic parameters, either fitted or obtained from literature. Our model allows the simulation of PD-related ROS generation and mitochondrial damage and the identification of the design principles underlying the functioning of the network; for example, showing and explaining the synergy between the down-regulation of both VDAC1 and PARK7 occurring during PD. The kinetic model has great potential use for better understanding of the pathophysiology of PD and for the suggestion of novel mitochondria-related PD treatments. [less ▲]

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See detailLa satisfaction au travail. Impact de quelques variables psycho-environnementales
Rioux, Liliane; Pignault, Anne UL

Poster (2012, July)

Detailed reference viewed: 64 (0 UL)