2,453 research outputs found
Effects of Heartwood Inhabiting Fungi on Thujaplicin Content and Decay Resistance of Western Redcedar (Thuja Plicata Donn.)
Western redcedar (Thuja plicata Donn.) outer heartwood blocks from a mature and an immature tree, inoculated with fungi commonly isolated from stained heartwood, had a thujaplicin content of less than 6% and a hot water solubility of about one-half that of controls after 10 weeks of exposure. Decay resistance of blocks from the mature tree was greatly reduced following exposure to the staining fungi. Naturally stained heartwood also had low thujaplicin content, but its decay resistance remained high in the same test
Attentional processes of high-skilled soccer players with congenital hemiparesis: Differences related to the side of the hemispheric lesion
Contains fulltext :
72909.pdf (publisher's version ) (Closed access)We investigated attentional processes that support the performance of high-skilled soccer players with hemiparetic cerebral palsy. Participants (N = 10) dribbled a slalom course as quickly and accurately as possible under two attentional-focus manipulation conditions. In the task-relevant focus condition, they attended to the foot that was in contact with the ball, whereas in the task-irrelevant focus condition, they monitored a series of words played on a tape. The time taken to complete the slalom course was registered. Performances of individuals with left and right hemiparesis were compared to explore differential effects of hemispheric lesion. The high-skilled players with congenital hemiparesis showed similar attentional-focus effects as those previously reported in the literature for high-skilled players without neurological disorders (Beilock et al., 2002; Ford et al., 2005). Task-relevant focus increased dribbling time, whereas a task-irrelevant focus did not result in a significant change in dribbling time. These findings generalized to each of the five participants with left hemiparesis (i.e., damage to the right hemisphere). By contrast, the effects of a task-relevant focus were less consistent for participants with right hemiparesis (i.e., left-hemisphere damage). This corroborates suggestions that the reinvestment of procedural knowledge is a left-lateralized function. The implications for the training of individuals with congenital brain damage are discussed
The effects of dust evolution on disks in the mid-IR
In this paper, we couple together the dust evolution code two-pop-py with the
thermochemical disk modelling code ProDiMo. We create a series of
thermochemical disk models that simulate the evolution of dust over time from
0.018 Myr to 10 Myr, including the radial drift, growth, and settling of dust
grains. We examine the effects of this dust evolution on the mid-infrared gas
emission, focussing on the mid-infrared spectral lines of C2H2, CO2, HCN, NH3,
OH, and H2O that are readily observable with Spitzer and the upcoming E-ELT and
JWST.
The addition of dust evolution acts to increase line fluxes by reducing the
population of small dust grains. We find that the spectral lines of all species
except C2H2 respond strongly to dust evolution, with line fluxes increasing by
more than an order of magnitude across the model series as the density of small
dust grains decreases over time. The C2H2 line fluxes are extremely low due to
a lack of abundance in the infrared line-emitting regions, despite C2H2 being
commonly detected with Spitzer, suggesting that warm chemistry in the inner
disk may need further investigation. Finally, we find that the CO2 flux
densities increase more rapidly than the other species as the dust disk
evolves. This suggests that the flux ratios of CO2 to other species may be
lower in disks with less-evolved dust populations.Comment: 13 pages, 9 figures, accepted in A&
Modally Resolved Fabry-Perot Experiment with Semiconductor Waveguides
Based on the interaction between different spatial modes, semiconductor
Bragg-reflection waveguides provide a highly functional platform for non-linear
optics. Therefore, the control and engineering of the properties of each
spatial mode is essential. Despite the multimodeness of our waveguide, the
well-established Fabry-Perot technique for recording fringes in the optical
transmission spectrum can successfully be employed for a detailed linear
optical characterization when combined with Fourier analysis. A prerequisite
for the modal sensitivity is a finely resolved transmission spectrum that is
recorded over a broad frequency band. Our results highlight how the features of
different spatial modes, such as their loss characteristics and dispersion
properties, can be separated from each other allowing their comparison. The
mode-resolved measurements are important for optimizing the performance of such
multimode waveguides by tailoring the properties of their spatial modes.Comment: 8 pages, 7 figure
Decay dynamics of quantum dots influenced by the local density of optical states of two-dimensional photonic crystal membranes
We have performed time-resolved spectroscopy on InAs quantum dot ensembles in
photonic crystal membranes. The influence of the photonic crystal is
investigated by varying the lattice constant systematically. We observe a
strong slow down of the quantum dots' spontaneous emission rates as the
two-dimensional bandgap is tuned through their emission frequencies. The
measured band edges are in full agreement with theoretical predictions. We
characterize the multi-exponential decay curves by their mean decay time and
find enhancement of the spontaneous emission at the bandgap edges and strong
inhibition inside the bandgap in good agreement with local density of states
calculations.Comment: 9 pages (preprint), 3 figure
Involutivity of integrals for sine-Gordon, modified KdV and potential KdV maps
Closed form expressions in terms of multi-sums of products have been given in
\cite{Tranclosedform, KRQ} of integrals of sine-Gordon, modified Korteweg-de
Vries and potential Korteweg-de Vries maps obtained as so-called
-traveling wave reductions of the corresponding partial difference
equations. We prove the involutivity of these integrals with respect to
recently found symplectic structures for those maps. The proof is based on
explicit formulae for the Poisson brackets between multi-sums of products.Comment: 24 page
The effect of the "Rod-and-frame" Illusion on grip planning in a sequential object manipulation task
We investigated the effect of visual context (i.e., a visual illusion) on the planning of a sequential object manipulation task. Participants (n = 13) had to grasp a rod embedded in a "rod-and-frame" illusion and insert the rod-end into a tight hole in a pre-defined way. The grip type (defined by start posture, either pronated or supinated; and end posture, either comfortable or uncomfortable) used to grasp the rod was registered as a macroscopic variable of motor planning. Different rod orientations forced the participants to switch between grip types. As expected, most participants switched between pronated and supinated start postures, such that they ended the movement with a comfortable end posture. As it has been argued that planning is dependent on visual context information, we hypothesized that the visual illusion would affect the specific rod orientation at which participants would switch into a different grip type. This hypothesis was confirmed. More specifically, the illusion affected the critical spatial information that is used for action planning. Collectively, these findings are the first to show an effect of an illusion on motor planning in a sequential object manipulation task. © 2007 Springer-Verlag
The staircase method: integrals for periodic reductions of integrable lattice equations
We show, in full generality, that the staircase method provides integrals for
mappings, and correspondences, obtained as traveling wave reductions of
(systems of) integrable partial difference equations. We apply the staircase
method to a variety of equations, including the Korteweg-De Vries equation, the
five-point Bruschi-Calogero-Droghei equation, the QD-algorithm, and the
Boussinesq system. We show that, in all these cases, if the staircase method
provides r integrals for an n-dimensional mapping, with 2r<n, then one can
introduce q<= 2r variables, which reduce the dimension of the mapping from n to
q. These dimension-reducing variables are obtained as joint invariants of
k-symmetries of the mappings. Our results support the idea that often the
staircase method provides sufficiently many integrals for the periodic
reductions of integrable lattice equations to be completely integrable. We also
study reductions on other quad-graphs than the regular 2D lattice, and we prove
linear growth of the multi-valuedness of iterates of high-dimensional
correspondences obtained as reductions of the QD-algorithm.Comment: 40 pages, 23 Figure
The Okubo-Weiss Criteria in Two-Dimensional Hydrodynamic and Magnetohydrodynamic Flows
The Okubo [2]-Weiss [3] criterion is recast by using the 2D hydrodynamic
Beltrami condition (Shivamoggi et al.[13]) that approximates the slow
flow-variation ansatz imposed in its derivation. This turns out to provide an
interesting interpretation of the Okubo-Weiss criterion very logically in terms
of the topological properties of the underlying vorticity manifold. These
developments are then extended to 2D quasi-geostrophic flows (via the potential
divorticity framework), magnetohydrodynamic flows and electron
magnetohydrodynamic flows (via the generalized magnetic flux framework) and the
Okubo-Weiss criteria for these cases are considered.Comment: 13 page
Modeling the gas-phase chemistry of the transitional disk around HD 141569A
Aims: The chemistry, distribution and mass of the gas in the transitional
disk around the 5 Myr old B9.5 V star HD 141569A are constrained.
Methods: A quasi 2-dimensional (2D) chemistry code for photon dominated
regions (PDR) is used to calculate the chemistry and gas temperatures in the
disk. The calculations are performed for several gas distributions, PAH
abundances and values of the total gas mass. The resulting CO J=2-1 and J=3-2
emission lines are computed with a 2D radiative transfer code and are compared
to observations.
Results: The CO abundance is very sensitive to the total disk mass because
the disk is in a regime where self-shielding just sets in. The observed CO
emission lines are best fit by a power-law gas distribution of 80 M_earth
starting at 80 AU from the central star, indicating that there is some gas in
the inner hole. Predictions are made for intensities of atomic fine-structure
lines. [C I], which is the dominant form of carbon in large parts of the disk,
is found to be a good alternative tracer of the gas mass.Comment: 11 pages, 9 figures. Accepted for publication in A&
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