12,584 research outputs found
Organic Farming Research Support and Research Priorities in the European Union
Support for Organic Farming focused research has increased significantly in successive EU research funding frameworks. This is in line with constantly increasing consumer demand for organic foods over the last 20 years, which has accelerated again over the last 2 years in many European countries, including new member states.
Under the 7th Framework Programme (FP7), the expected new increase of funds for organic farming could significantly decrease, even below the levels made available under the 5th Framework Programme (FP5). Most of the project topics listed focus on the development of methods for economic analyses of Organic Farming and/or follow a very “reductionist” one problem - one potential solution approach.
On the other side, as there is no clear instruments to establish priorities in research programmes at European level. The IFOAM EU Group has developed a consultation process to set organic farming sector priorities, which could be used as a model to set research priorities in the future.
This paper also presents a first assessment of the EU support to organic farming research, reviewing main achievements in organic food production systems research and proposing some changes in the current 7th Framework Programme
Asteroseismology of eclipsing binary stars using Kepler and the HERMES spectrograph
We introduce our PhD project in which we focus on pulsating stars in
eclipsing binaries. The combination of high-precision Kepler photometry with
high-resolution HERMES spectroscopy allows for detailed descriptions of our
sample of target stars. We report here the detection of three false positives
by radial velocity measurements.Comment: Proceedings paper, 2 pages, 2 figures, to appear in "Setting a New
Standard in the Analysis of Binary Stars", Eds K. Pavlovski, A. Tkachenko,
and G. Torres, EAS Publications Serie
Anisotropic flow in striped superhydrophobic channels
We report results of dissipative particle dynamics simulations and develop a
semi-analytical theory of an anisotropic flow in a parallel-plate channel with
two superhydrophobic striped walls. Our approach is valid for any local slip at
the gas sectors and an arbitrary distance between the plates, ranging from a
thick to a thin channel. It allows us to optimize area fractions, slip lengths,
channel thickness and texture orientation to maximize a transverse flow. Our
results may be useful for extracting effective slip tensors from global
measurements, such as the permeability of a channel, in experiments or
simulations, and may also find applications in passive microfluidic mixing.Comment: 11 pages, 10 figures, submitted to J. Chem. Phy
Spin nematics in the bilinear-biquadratic S=1 spin chain
We report the existence of an extended critical, nondimerized region in the
phase diagram of the bilinear-biquadratic spin-one chain. The dominant power
law correlations are ferroquadrupolar, i.e. spin nematic in character. Another
known critical region is also characterized by dominant quadrupolar
correlations, although with a different wave vector. Our results show that spin
nematic correlations play an important role in quantum magnets with spin S >= 1
in regions between antiferromagnetic and ferromagnetic phases.Comment: 4 pages, 7 figure
Coarse Woody Debris and the Carbon Balance of a Moderately Disturbed Forest
Landscapes are comprised of multiple ecosystems shaped by disturbances varying in severity and source. Moderate disturbance from weather, pathogens, insects, and age-related senescence, in contrast to severe disturbances that fell trees, may increase standing woody debris and alter the contribution of coarse woody debris (CWD) to total ecosystem respiration (RE). However, woody debris dynamics are rarely examined following moderate disturbances that substantially increase standing dead wood stocks. We used an experimental manipulation of moderate disturbance in an upper Great Lakes forest to: 1) examine decadal changes in CWD stocks through a moderate disturbance; 2) quantify in situ CWD respiration during different stages of decay for downed and standing woody debris and; 3) estimate the annual contribution of CWD respiration to the ecosystem C balance through comparison with RE and net ecosystem production (NEP). We found that the standing dead wood mass of 24.5 Mg C ha-1 was an order of magnitude greater than downed woody debris stocks and a large source of ecosystem C flux six years following disturbance. Instantaneous in situ respiration rates from standing and downed woody debris in the earliest stages of decay were not significantly different from one another. Independently derived estimates of ecosystem CWD respiration of 1.1to 2.1 Mg C ha-1 yr-1 six years following disturbance were comparable in magnitude to NEP and 12.5 % to 23.8 % of RE, representing a substantial increase relative to pre-disturbance levels. Ecosystem respiration and NEP were stable following moderate disturbance even though ecosystem CWD respiration increased substantially, suggesting a reduction in the respiratory C contribution from other sources. We conclude that CWD is an essential component of the ecosystem C balance following a moderate forest disturbance
Giant enhancement of hydrodynamically enforced entropic trapping in thin channels
Using our generalized Fick-Jacobs approach [Martens et al., PRL 110, 010601
(2013); Martens et al., Eur. Phys. J. Spec. Topics 222, 2453-2463 (2013)] and
extensive Brownian dynamics simulations, we study particle transport through
three-dimensional periodic channels of different height. Directed motion is
caused by the interplay of constant bias acting along the channel axis and a
pressure-driven flow. The tremendous change of the flow profile shape in
channel direction with the channel height is reflected in a crucial dependence
of the mean particle velocity and the effective diffusion coefficient on the
channel height. In particular, we observe a giant suppression of the effective
diffusivity in thin channels; four orders of magnitude compared to the bulk
value.Comment: 16 pages, 8 figure
Hydrodynamically enforced entropic trapping of Brownian particles
We study the transport of Brownian particles through a corrugated channel
caused by a force field containing curl-free (scalar potential) and
divergence-free (vector potential) parts. We develop a generalized Fick-Jacobs
approach leading to an effective one-dimensional description involving the
potential of mean force. As an application, the interplay of a pressure-driven
flow and an oppositely oriented constant bias is considered. We show that for
certain parameters, the particle diffusion is significantly suppressed via the
property of hyrodynamically enforced entropic particle trapping.Comment: 5 pages, 4 figures, in press with Physical Review Letter
Three-body breakup within the fully discretized Faddeev equations
A novel approach is developed to find the three-body breakup amplitudes and
cross sections within the modified Faddeev equation framework. The method is
based on the lattice-like discretization of the three-body continuum with a
three-body stationary wave-packet basis in momentum space. The approach makes
it possible to simplify drastically all the three- and few-body breakup
calculations due to discrete wave-packet representations for the few-body
continuum and simultaneous lattice representation for all the scattering
operators entering the integral equation kernels. As a result, the few-body
breakup can be treated as a particular case of multi-channel scattering in
which part of the channels represents the true few-body continuum states. As an
illustration for the novel approach, an accurate calculations for the
three-body breakup process with non-local and local
interactions are calculated. The results obtained reproduce nicely the
benchmark calculation results using the traditional Faddeev scheme which
requires much more tedious and time-consuming calculations.Comment: 17 pages, 13 figure
Flows and mixing in channels with misaligned superhydrophobic walls
Aligned superhydrophobic surfaces with the same texture orientation reduce
drag in the channel and generate secondary flows transverse to the direction of
the applied pressure gradient. Here we show that a transverse shear can be
easily generated by using superhydrophobic channels with misaligned textured
surfaces. We propose a general theoretical approach to quantify this transverse
flow by introducing the concept of an effective shear tensor. To illustrate its
use, we present approximate theoretical solutions and Dissipative Particle
Dynamics simulations for striped superhydrophobic channels. Our results
demonstrate that the transverse shear leads to complex flow patterns, which
provide a new mechanism of a passive vertical mixing at the scale of a texture
period. Depending on the value of Reynolds number two different scenarios
occur. At relatively low Reynolds number the flow represents a transverse shear
superimposed with two co-rotating vortices. For larger Reynolds number these
vortices become isolated, by suppressing fluid transport in the transverse
direction.Comment: 8 pages, 10 figure
- …