1,173 research outputs found
Mangelnde Kenntnis über den Anbau von Körnerleguminosen bei Luxemburger Landwirten
Grain legume production in Europe has decreased in recent years, while legume demand has rapidly increased. Various investigations have identified problems and benefits of grain legume cultivation. Studies investigating why farmers do not cultivate these crops are missing. Here we surveyed farmers about grain legume cultivation. We sent a questionnaire to 1373 farmers in Luxembourg, with a response rate of 29%. Results show that 12% of the conventional and 85% of the organic farmers cultivated grain legumes. We observed that farmers feel badly informed about grain legume
cultivation. The main barriers to not cultivate these crops are not economic issues but a lack of knowledge about grain legumes. Even though grain legume producers mentioned several negative experiences with grain legume cultivation, they are not discouraged by the poor economic conditions and appreciate the benefits of grain legume cultivation. Overall our findings show that research results on grain legumes
should be better disseminated to extension services and farmers
Multidrug-Resistant Lineage of Enterotoxigenic Escherichia coli ST182 With Serotype O169:H41 in Airline Waste.
Enterotoxigenic Escherichia coli (ETEC) is the primary aetiologic agent of traveller's diarrhoea and a significant cause of diarrhoeal disease and death in developing countries. ETEC O169:H41 strains are known to cause both traveller's diarrhoea and foodborne outbreaks in developed countries and are cause for concern. Here, whole-genome sequencing (WGS) was used to assemble 46 O169:H41 (ST182) E. coli draft genomes derived from two airplane waste samples sourced from a German international airport. The ST182 genomes were compared with all 84 publicly available, geographically diverse ST182 genomes to construct a core genome-based phylogenetic tree. ST182 isolates were all phylogroup E, the majority serotype O169:H41 (n = 121, 93%) and formed five major clades. The airplane waste isolates differed by an average of 15 core SNPs (range 0-45) but their accessory genome content was diverse. While uncommon in other ST182 genomes, all airplane-derived ST182 isolates carried: (i) extended-spectrum β-lactamase gene bla CTX-M- 15 notably lacking the typical adjacent ISEcp1; (ii) qnrS1 and the S83L mutation in gyrA, both conferring resistance to fluoroquinolones; and (iii) a class 1 integron structure (IS26-intI1 Δ 648-dfrA17-aadA5-qacEΔ1-sul1-ORF-srpC-padR-IS6100-mphR-mrx-mphA-IS26) identified previously in major extraintestinal pathogenic E. coli STs but not in ETEC. ST182 isolates carried ETEC-specific virulence factors STp + CS6. Adhesin/invasin tia was identified in 89% of aircraft ST182 isolates (vs 23%) and was located on a putative genomic island within a hotspot region for various insertions including PAI I536 and plasmid-associated transposons. The most common plasmid replicons in this collection were IncFII (100%; F2:A-:B-) and IncB/O/K/Z (89%). Our data suggest that potentially through travel, E. coli ST182 are evolving a multidrug-resistant profile through the acquisition of class 1 integrons and different plasmids
SGARFACE: A Novel Detector For Microsecond Gamma Ray Bursts
The Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) is operated at
the Whipple Observatory utilizing the Whipple 10m gamma-ray telescope. SGARFACE
is sensitive to gamma-ray bursts of more than 100MeV with durations from 100ns
to 35us and provides a fluence sensitivity as low as 0.8 gamma-rays per m^2
above 200MeV (0.05 gamma-rays per m^2 above 2GeV) and allows to record the
burst time structure.Comment: 29 pages, 14 figures, accepted for publication in Astroparticle
Physic
Hydrodynamic simulations with the Godunov SPH
We present results based on an implementation of the Godunov Smoothed
Particle Hydrodynamics (GSPH), originally developed by Inutsuka (2002), in the
GADGET-3 hydrodynamic code. We first review the derivation of the GSPH
discretization of the equations of moment and energy conservation, starting
from the convolution of these equations with the interpolating kernel. The two
most important aspects of the numerical implementation of these equations are
(a) the appearance of fluid velocity and pressure obtained from the solution of
the Riemann problem between each pair of particles, and (b the absence of an
artificial viscosity term. We carry out three different controlled
hydrodynamical three-dimensional tests, namely the Sod shock tube, the
development of Kelvin-Helmholtz instabilities in a shear flow test, and the
"blob" test describing the evolution of a cold cloud moving against a hot wind.
The results of our tests confirm and extend in a number of aspects those
recently obtained by Cha (2010): (i) GSPH provides a much improved description
of contact discontinuities, with respect to SPH, thus avoiding the appearance
of spurious pressure forces; (ii) GSPH is able to follow the development of
gas-dynamical instabilities, such as the Kevin--Helmholtz and the
Rayleigh-Taylor ones; (iii) as a result, GSPH describes the development of curl
structures in the shear-flow test and the dissolution of the cold cloud in the
"blob" test.
We also discuss in detail the effect on the performances of GSPH of changing
different aspects of its implementation. The results of our tests demonstrate
that GSPH is in fact a highly promising hydrodynamic scheme, also to be coupled
to an N-body solver, for astrophysical and cosmological applications.
[abridged]Comment: 19 pages, 13 figures, MNRAS accepted, high resolution version can be
obtained at
http://adlibitum.oats.inaf.it/borgani/html/papers/gsph_hydrosim.pd
On the potential of augmented reality for mathematics teaching with the application cleARmaths
Learning content in mathematics, such as vector geometry, is still predominantly taught in an abstract manner, as the visualization and interaction of three-dimensional problems are limited with classical forms of teaching such as blackboard lessons or exercise sheets. This research article proposes the use of augmented reality (AR) in mathematics education. The proposed approach aims at easing the learning process related to vector geometry currently taught in senior mathematics classes by using intuitive visualization. The article introduces the concept of AR and presents the didactic foundations and the influence on the learning process based on an extensive literature review. Although studies see great potential in the use of AR for teaching mathematics, the method has so far hardly been used in schools. This can be mainly explained by the technological entry barrier of AR and the lack of simple, robust AR applications, in particular for vector geometry. To fill this gap, the authors developed “cleARmaths”, a developed android application for augmented reality-based teaching in vector geometry that allows widespread use. As a didactical concept, some example exercises sessions with the app are proposed, demonstrating how the app could be used in a mathematics classroom. Finally, the app was evaluated in a mathematics class and the results analyzed in a detailed study. It was found by the teacher and students to be beneficial and amusing, demonstrating the potential for AR in mathematics classes
Simulating Turbulence Using the Astrophysical Discontinuous Galerkin Code TENET
In astrophysics, the two main methods traditionally in use for solving the
Euler equations of ideal fluid dynamics are smoothed particle hydrodynamics and
finite volume discretization on a stationary mesh. However, the goal to
efficiently make use of future exascale machines with their ever higher degree
of parallel concurrency motivates the search for more efficient and more
accurate techniques for computing hydrodynamics. Discontinuous Galerkin (DG)
methods represent a promising class of methods in this regard, as they can be
straightforwardly extended to arbitrarily high order while requiring only small
stencils. Especially for applications involving comparatively smooth problems,
higher-order approaches promise significant gains in computational speed for
reaching a desired target accuracy. Here, we introduce our new astrophysical DG
code TENET designed for applications in cosmology, and discuss our first
results for 3D simulations of subsonic turbulence. We show that our new DG
implementation provides accurate results for subsonic turbulence, at
considerably reduced computational cost compared with traditional finite volume
methods. In particular, we find that DG needs about 1.8 times fewer degrees of
freedom to achieve the same accuracy and at the same time is more than 1.5
times faster, confirming its substantial promise for astrophysical
applications.Comment: 21 pages, 7 figures, to appear in Proceedings of the SPPEXA
symposium, Lecture Notes in Computational Science and Engineering (LNCSE),
Springe
Galaxies undergoing ram-pressure stripping: the influence of the bulge on morphology and star formation rate
We investigate the influence of stellar bulges on the star formation and
morphology of disc galaxies that suffer from ram pressure. Several tree-SPH
(smoothed particle hydrodynamics) simulations have been carried out to study
the dependence of the star formation rate on the mass and size of a stellar
bulge. In addition, different strengths of ram pressure and different
alignments of the disc with respect to the intra-cluster medium (ICM) are
applied. As claimed in previous works, when ram pressure is acting on a galaxy,
the star formation rate (SFR) is enhanced and rises up to four times with
increasing ICM density compared to galaxies that evolve in isolation. However,
a bulge suppresses the SFR when the same ram pressure is applied. Consequently,
fewer new stars are formed because the SFR can be lowered by up to 2 M_sun/yr.
Furthermore, the denser the surrounding gas, the more inter-stellar medium
(ISM) is stripped. While at an ICM density of 10^-28 g/cm^3 about 30% of the
ISM is stripped, the galaxy is almost completely (more than 90%) stripped when
an ICM density of 10^-27 g/cm^3 is applied. But again, a bulge prevents the
stripping of the ISM and reduces the amount being stripped by up to 10%.
Thereby, fewer stars are formed in the wake if the galaxy contains a bulge. The
dependence of the SFR on the disc tilt angle is not very pronounced. Hereby a
slight trend of decreasing star formation with increasing inclination angle can
be determined. Furthermore, with increasing disc tilt angles, less gas is
stripped and therefore fewer stars are formed in the wake. Reducing the disc
gas mass fraction results in a lower SFR when the galaxies evolve in vacuum. On
the other hand, the enhancement of the SFR in case of acting ram pressure is
less pronounced with increasing gas mass fraction. Moreover, the fractional
amount of stripped gas does not depend on the gas mass fraction.Comment: 11 pages, 18 figure
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