341 research outputs found
Opportunities and Challenges of Extracting Values in Autobiographical Narratives
We report three studies in which we applied a value dictionary to narratives. Our objective was to test a theory-driven value dictionary for extracting valuable information from autobiographical and narrative texts. In Studies 1 (N = 106) and 2 (N = 152), participants wrote short autobiographical narratives and in Study 3 (N = 150), participants wrote narratives based on ambiguous stimuli. Participants in all three studies also completed the Portrait Value Questionnaire as a self-report measure of values. Overall, our results demonstrate that it is possible to extract value-relevant information from these narratives. Extracted values from autobiographical narratives showed average correlations of 0.07 (Study 1) and 0.12 (Study 2) with self-reports compared to an average correlation of 0.01 for the extracted values from implicit motive tasks (Study 3). The correlations with self-reports were in line with previous validation studies. The most salient values in narratives diverged somewhat, with a stronger emphasis on achievement values compared to self-reports, probably due to the nature of salient episodes within one's life that require demonstrating success according to social standards. Benevolence values were consistently most important in both self-ratings and text-based scoring. The value structure emerging from narratives diverged from the theoretically predicted structure, yet broad personally vs. socially focused value dimensions were qualitatively discernible. We highlight opportunities and challenges for future value research using autobiographical stories
Gravin orchestrates protein kinase A and 2-adrenergic receptor signaling critical for synaptic plasticity and memory
A kinase-anchoring proteins (AKAPs) organize compartmentalized pools of protein kinase A (PKA) to enable localized signaling events within neurons. However, it is unclear which of the many expressed AKAPs in neurons target PKA to signaling complexes important for long-lasting forms of synaptic plasticity and memory storage. In the forebrain, the anchoring protein gravin recruits a signaling complex containing PKA, PKC, calmodulin, and PDE4D (phosphodiesterase 4D) to the β2-adrenergic receptor. Here, we show that mice lacking the α-isoform of gravin have deficits in PKA-dependent long-lasting forms of hippocampal synaptic plasticity including β2-adrenergic receptor-mediated plasticity, and selective impairments of long-term memory storage. Furthermore, both hippocampal β2-adrenergic receptor phosphorylation by PKA, and learning-induced activation of ERK in the CA1 region of the hippocampus are attenuated in mice lacking gravin-α. We conclude that gravin compartmentalizes a significant pool of PKA that regulates learning-induced β2-adrenergic receptor signaling and ERK activation in the hippocampus in vivo, thereby organizing molecular interactions between glutamatergic and noradrenergic signaling pathways for long-lasting synaptic plasticity, and memory storage
Bipolaron Binding in Quantum Wires
A theory of bipolaron states in quantum wires with a parabolic potential well
is developed applying the Feynman variational principle. The basic parameters
of the bipolaron ground state (the binding energy, the number of phonons in the
bipolaron cloud, the effective mass, and the bipolaron radius) are studied as a
function of sizes of the potential well. Two cases are considered in detail: a
cylindrical quantum wire and a planar quantum wire. Analytical expressions for
the bipolaron parameters are obtained at large and small sizes of the quantum
well. It is shown that at [where means the radius (halfwidth) of a
cylindrical (planar) quantum wire, expressed in Feynman units], the influence
of confinement on the bipolaron binding energy is described by the function
for both cases, while at small sizes this influence is different
in each case. In quantum wires, the bipolaron binding energy increases
logarithmically with decreasing radius. The shapes and the sizes of a
nanostructure, which are favorable for observation of stable bipolaron states,
are determined.Comment: 17 pages, 6 figures, E-mail addresses: [email protected];
[email protected]
Scaling of a large-scale simulation of synchronous slow-wave and asynchronous awake-like activity of a cortical model with long-range interconnections
Cortical synapse organization supports a range of dynamic states on multiple
spatial and temporal scales, from synchronous slow wave activity (SWA),
characteristic of deep sleep or anesthesia, to fluctuating, asynchronous
activity during wakefulness (AW). Such dynamic diversity poses a challenge for
producing efficient large-scale simulations that embody realistic metaphors of
short- and long-range synaptic connectivity. In fact, during SWA and AW
different spatial extents of the cortical tissue are active in a given timespan
and at different firing rates, which implies a wide variety of loads of local
computation and communication. A balanced evaluation of simulation performance
and robustness should therefore include tests of a variety of cortical dynamic
states. Here, we demonstrate performance scaling of our proprietary Distributed
and Plastic Spiking Neural Networks (DPSNN) simulation engine in both SWA and
AW for bidimensional grids of neural populations, which reflects the modular
organization of the cortex. We explored networks up to 192x192 modules, each
composed of 1250 integrate-and-fire neurons with spike-frequency adaptation,
and exponentially decaying inter-modular synaptic connectivity with varying
spatial decay constant. For the largest networks the total number of synapses
was over 70 billion. The execution platform included up to 64 dual-socket
nodes, each socket mounting 8 Intel Xeon Haswell processor cores @ 2.40GHz
clock rates. Network initialization time, memory usage, and execution time
showed good scaling performances from 1 to 1024 processes, implemented using
the standard Message Passing Interface (MPI) protocol. We achieved simulation
speeds of between 2.3x10^9 and 4.1x10^9 synaptic events per second for both
cortical states in the explored range of inter-modular interconnections.Comment: 22 pages, 9 figures, 4 table
The wavefront of the radio signal emitted by cosmic ray air showers
Analyzing measurements of the LOPES antenna array together with corresponding
CoREAS simulations for more than 300 measured events with energy above
eV and zenith angles smaller than , we find that the radio
wavefront of cosmic-ray air showers is of approximately hyperbolic shape. The
simulations predict a slightly steeper wavefront towards East than towards
West, but this asymmetry is negligible against the measurement uncertainties of
LOPES. At axis distances m, the wavefront can be approximated by
a simple cone. According to the simulations, the cone angle is clearly
correlated with the shower maximum. Thus, we confirm earlier predictions that
arrival time measurements can be used to study the longitudinal shower
development, but now using a realistic wavefront. Moreover, we show that the
hyperbolic wavefront is compatible with our measurement, and we present several
experimental indications that the cone angle is indeed sensitive to the shower
development. Consequently, the wavefront can be used to statistically study the
primary composition of ultra-high energy cosmic rays. At LOPES, the
experimentally achieved precision for the shower maximum is limited by
measurement uncertainties to approximately g/cm. But the simulations
indicate that under better conditions this method might yield an accuracy for
the atmospheric depth of the shower maximum, , better than
g/cm. This would be competitive with the established air-fluorescence
and air-Cherenkov techniques, where the radio technique offers the advantage of
a significantly higher duty-cycle. Finally, the hyperbolic wavefront can be
used to reconstruct the shower geometry more accurately, which potentially
allows a better reconstruction of all other shower parameters, too.Comment: accepted by JCA
KCDC - The KASCADE Cosmic-ray Data Centre
KCDC, the KASCADE Cosmic-ray Data Centre, is a web portal, where data of
astroparticle physics experiments will be made available for the interested
public. The KASCADE experiment, financed by public money, was a large-area
detector for the measurement of high-energy cosmic rays via the detection of
air showers. KASCADE and its extension KASCADE-Grande stopped finally the
active data acquisition of all its components including the radio EAS
experiment LOPES end of 2012 after more than 20 years of data taking. In a
first release, with KCDC we provide to the public the measured and
reconstructed parameters of more than 160 million air showers. In addition,
KCDC provides the conceptional design, how the data can be treated and
processed so that they are also usable outside the community of experts in the
research field. Detailed educational examples make a use also possible for
high-school students and early stage researchers.Comment: 8 pages, accepted proceeding of the ECRS-symposium, Kiel, 201
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