7,035 research outputs found
Searching for plasticity in dissociated cortical cultures on multi-electrode arrays
We attempted to induce functional plasticity in dense cultures of cortical cells using stimulation through extracellular electrodes embedded in the culture dish substrate (multi-electrode arrays, or MEAs). We looked for plasticity expressed in changes in spontaneous burst patterns, and in array-wide response patterns to electrical stimuli, following several induction protocols related to those used in the literature, as well as some novel ones. Experiments were performed with spontaneous culture-wide bursting suppressed by either distributed electrical stimulation or by elevated extracellular magnesium concentrations as well as with spontaneous bursting untreated. Changes concomitant with induction were no larger in magnitude than changes that occurred spontaneously, except in one novel protocol in which spontaneous bursts were quieted using distributed electrical stimulation
Observational evidence for matter propagation in accretion flows
We study simultaneous X-ray and optical observations of three intermediate
polars EX Hya, V1223 Sgr and TV Col with the aim to understand the propagation
of matter in their accretion flows. We show that in all cases the power spectra
of flux variability of binary systems in X-rays and in optical band are similar
to each other and the majority of X-ray and optical fluxes are correlated with
time lag <1 sec. These findings support the idea that optical emission of
accretion disks, in these binary systems,largely originates as reprocessing of
X-ray luminosity of their white dwarfs. In the best obtained dataset of EX Hya
we see that the optical lightcurve unambiguously contains some component, which
leads the X-ray emission by ~7 sec. We interpret this in the framework of the
model of propagating fluctuations and thus deduce the time of travel of the
matter from the innermost part of the truncated accretion disk to the white
dwarf surface. This value agrees very well with the time expected for matter
threaded onto the magnetosphere of the white dwarf to fall to its surface. The
datasets of V1223 Sgr and TV Col in general confirm these findings,but have
poorer quality.Comment: 7 pages, 6 figures. Accepted for publication in MNRA
Measuring ambiguity attitude: (Extended) multiplier preferences for the American and the Dutch population
Empirical studies of ambiguity aversion often use measures that are not grounded in theory. This paper shows how a theoretically-founded measure of ambiguity aversion can be derived from Hansen and Sargentâs theory of multiplier preferences. Multiplier preferences are used in macroeconomics to capture model uncertainty. At the micro level, they have not been applied yet, because they do not permit ambiguity seeking, which is usually observed for a substantial proportion of subjects. We give a preference foundation for (extended) multiplier preferences accommodating both ambiguity aversion and ambiguity seeking and we propose a simple method to measure them using matching probabilities. We illustrate our method in two large representative samples (Dutch and American) and obtain the first micro estimates of multiplier preferences
Resistance of a domain wall in the quasiclassical approach
Starting from a simple microscopic model, we have derived a kinetic equation
for the matrix distribution function. We employed this equation to calculate
the conductance in a mesoscopic F'/F/F' structure with a domain wall (DW).
In the limit of a small exchange energy and an abrupt DW, the conductance
of the structure is equal to . Assuming that the scattering times
for electrons with up and down spins are close to each other we show that the
account for a finite width of the DW leads to an increase in this conductance.
We have also calculated the spatial distribution of the electric field in the F
wire. In the opposite limit of large (adiabatic variation of the
magnetization in the DW) the conductance coincides in the main approximation
with the conductance of a single domain structure . The account for rotation of
the magnetization in the DW leads to a negative correction to this conductance.
Our results differ from the results in papers published earlier.Comment: 11 pages; replaced with revised versio
Hydrodynamics near the QCD Phase Transition: Looking for the Longest-Lived Fireball
We propose a new strategy for the experimental search of the QCD phase
transition in heavy ion collisions: One may tune collision energy around the
point where the lifetime of the fireball is expected to be longest. We
demonstrate that the hydrodynamic evolution of excited nuclear matter does
change dramatically as the initial energy density goes through the "softest
point" (where the pressure to energy density ratio reaches its minimum). For
our choice of equation of state, this corresponds to epsilon_i approx. = 1.5
GeV/fm^3 and collision energy E_lab/A approx. = 30 GeV (for Au+Au). Various
observables seem to show distinct changes near the softest point.Comment: 7 pages, 3 Postscript figures (tar compressed and uuencoded)
submitte
Formalising the Continuous/Discrete Modeling Step
Formally capturing the transition from a continuous model to a discrete model
is investigated using model based refinement techniques. A very simple model
for stopping (eg. of a train) is developed in both the continuous and discrete
domains. The difference between the two is quantified using generic results
from ODE theory, and these estimates can be compared with the exact solutions.
Such results do not fit well into a conventional model based refinement
framework; however they can be accommodated into a model based retrenchment.
The retrenchment is described, and the way it can interface to refinement
development on both the continuous and discrete sides is outlined. The approach
is compared to what can be achieved using hybrid systems techniques.Comment: In Proceedings Refine 2011, arXiv:1106.348
The Discursive Denial of Racism by Finnish Populist Radical Right Politicians Accused of Anti-Muslim Hate-Speech
This chapter explores Finnish populist radical right politiciansâ discursive denials of racism against Muslims following the 2015 European ârefugee crisisâ. The critical discursive psychological analysis of the politiciansâ Facebook accounts identifies four ways in which racism was denied: first, through constructing the statements as mere displays of undisputable facts and common-sense; second, through personal narratives and ontological gerrymandering that acted as âproofâ of the politicianâs non-racist disposition; third, through transferring the discussion from issues about race to concern matters of cultural threats; and, fourth, through reversing racism to the politiciansâ political antagonists. The analyses show that in their discursive denial of racist hate-speech against Muslims, the Finnish politicians relied more on cultural arguments than welfare-protectionist ones. That is, the denials were primarily warranted through nostalgic references to Finnish national identity, people and values, and rhetorical promises that the hope of saving these rests on resisting the cultural threat posed by Islam.Peer reviewe
WormBase 2007
WormBase (www.wormbase.org) is the major publicly available database of information about Caenorhabditis elegans, an important system for basic biological and biomedical research. Derived from the initial ACeDB database of C. elegans genetic and sequence information, WormBase now includes the genomic, anatomical and functional information about C. elegans, other Caenorhabditis species and other nematodes. As such, it is a crucial resource not only for C. elegans biologists but the larger biomedical and bioinformatics communities. Coverage of core areas of C. elegans biology will allow the biomedical community to make full use of the results of intensive molecular genetic analysis and functional genomic studies of this organism. Improved search and display tools, wider cross-species comparisons and extended ontologies are some of the features that will help scientists extend their research and take advantage of other nematode species genome sequences
High modulus regenerated cellulose fibers spun from a low molecular weight microcrystalline cellulose solution
We have developed a novel process to convert low molecular weight microcrystalline cellulose into stiff regenerated cellulose fibers using a dry-jet wet fiber spinning process. Highly aligned cellulose fibers were spun from optically anisotropic microcrystalline cellulose/1-ethyl-3-methylimidazolium diethyl phosphate (EMImDEP) solutions. As the cellulose concentration increased from 7.6 to 12.4 wt %, the solution texture changed from completely isotropic to weakly nematic. Higher concentration solutions (>15 wt %) showed strongly optically anisotropic patterns, with clearing temperatures ranging from 80 to 90 °C. Cellulose fibers were spun from 12.4, 15.2, and 18.0 wt % cellulose solutions. The physical properties of these fibers were studied by scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD), and tensile testing. The 18.0 wt % cellulose fibers, with an average diameter of âŒ20 ÎŒm, possessed a high Youngâs modulus up to âŒ22 GPa, moderately high tensile strength of âŒ305 MPa, as well as high alignment of cellulose chains along the fiber axis confirmed by X-ray diffraction. This process presents a new route to convert microcrystalline cellulose, which is usually used for low mechanical performance applications (matrix for pharmaceutical tablets and food ingredients, etc.) into stiff fibers which can potentially be used for high-performance composite materials
Practitioner accounts and knowledge production: an analysis of three marketing discourses
Responding to repeated calls for marketing academicians to connect with marketing actors, we offer an empirically-sourced discourse analysis of the ways in which managers portray their practices. Focusing on the micro-discourses and narratives that marketing actors draw upon to represent their work we argue that dominant representations of marketing knowledge production present a number of critical concerns for marketing theory and marketing education. We also evidence that the often promoted idea of a need to close the gap between theory - as a dominant discourse - and practice, as a way of doing marketing, is problematic to pursue. We suggest that a more fruitful agenda resides in the development of a range of polyphonic and creative micro-discourses of management, promoting context, difference and individual meaning in marketing knowledge production
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