1,361 research outputs found
Resource effective control of Elymus repens
Preliminary results show that there is room for improvement within existing control methods of couch grass (Elymus repens (L.) Gould). It may be possible to reduce the number of stubble cultivations during autumn by timing the treatment, and to reduce the cultivation depth by using a goose foot cultivator (5 cm) instead of a disc cultivator (10 cm), without sacrificing couch grass control efficiency. The first year of the experiment, the use of a goose foot cultivator resulted in less nitrogen leaching than cultivation by disc. A reduced number of stubble cultivations potentially reduces nutrient loss, fuel consumption and the workload of the farmer.
Our experiments with cover crops to control couch grass in cereals has yet to prove significant effects on couch grass control, but cover crops combined with goose foot hoeing did reduce nitrogen leaching by more than a third compared to cultivation by disc. Further data is necessary to see if the system can be used to effectively control couch grass without significant yield losses. Regardless, it can reduce nitrogen leaching and potentially provide other ecosystem services, e.g. control weeds other than couch grass
Assessing the rider's seat and horse's behavior: difficulties and perspectives
correct seat and position are the basis for a good performance in horseback riding. This study aimed to measure deviations from the correct seat, test a seat improvement program (dismounted exercises), and investigate whether horse behavior was affected by the rider's seat. Five experienced trainers defined 16 seat deviations and scored the occurrence in 20 riders in a dressage test. Half the riders then carried out an individual training program; after 9 weeks, riders were again scored. The study took no video or heart-rate recordings of horses and riders. Panel members did not agree on the deviations in the rider's seat; the study detected no differencesÂżwith the exception of improvement of backward-tilted pelvisÂżbetween the groups. Horse behavior, classified as Âżevasive,Âż increased; horse heart rate decreased in the experimental group. Heart rates of riders in both groups decreased. Seven of 9 riders in the experimental group had the impression that the exercises improved their riding performance. There is a clear need to develop a robust system that allows trainers to objectively evaluate the rider's sea
A Holder Continuous Nowhere Improvable Function with Derivative Singular Distribution
We present a class of functions in which is variant
of the Knopp class of nowhere differentiable functions. We derive estimates
which establish \mathcal{K} \sub C^{0,\al}(\R) for 0<\al<1 but no is pointwise anywhere improvable to C^{0,\be} for any \be>\al.
In particular, all 's are nowhere differentiable with derivatives singular
distributions. furnishes explicit realizations of the functional
analytic result of Berezhnoi.
Recently, the author and simulteously others laid the foundations of
Vector-Valued Calculus of Variations in (Katzourakis), of
-Extremal Quasiconformal maps (Capogna and Raich, Katzourakis) and of
Optimal Lipschitz Extensions of maps (Sheffield and Smart). The "Euler-Lagrange
PDE" of Calculus of Variations in is the nonlinear nondivergence
form Aronsson PDE with as special case the -Laplacian.
Using , we construct singular solutions for these PDEs. In the
scalar case, we partially answered the open regularity problem of
Viscosity Solutions to Aronsson's PDE (Katzourakis). In the vector case, the
solutions can not be rigorously interpreted by existing PDE theories and
justify our new theory of Contact solutions for fully nonlinear systems
(Katzourakis). Validity of arguments of our new theory and failure of classical
approaches both rely on the properties of .Comment: 5 figures, accepted to SeMA Journal (2012), to appea
Existence and uniqueness of global solutions to fully nonlinear second order elliptic systems
We consider the problem of existence and uniqueness of strong a.e. solutions u:Rnâ¶RNu:Rnâ¶RN to the fully nonlinear PDE system
F(â
,D2u)=f, a.e. on Rn,(1)
F(â
,D2u)=f, a.e. on Rn,(1)
when fâL2(Rn)NfâL2(Rn)N and F is a CarathĂ©odory map. (1) has not been considered before. The case of bounded domains has been studied by several authors, firstly by Campanato and under Campanatoâs ellipticity condition on F. By introducing a new much weaker notion of ellipticity, we prove solvability of (1) in a tailored Sobolev âenergyâ space and a uniqueness estimate. The proof is based on the solvability of the linearised problem by Fourier transform methods, together with a âperturbation deviceâ which allows to use Campanatoâs near operators. We also discuss our hypothesis via counterexamples and give a stability theorem of strong global solutions for systems of the form (1)
A nonhomogeneous boundary value problem in mass transfer theory
We prove a uniqueness result of solutions for a system of PDEs of
Monge-Kantorovich type arising in problems of mass transfer theory. The results
are obtained under very mild regularity assumptions both on the reference set
, and on the (possibly asymmetric) norm defined in
. In the special case when is endowed with the Euclidean
metric, our results provide a complete description of the stationary solutions
to the tray table problem in granular matter theory.Comment: 22 pages, 2 figure
Quasivariational solutions for first order quasilinear equations with gradient constraint
We prove the existence of solutions for an evolution quasi-variational
inequality with a first order quasilinear operator and a variable convex set,
which is characterized by a constraint on the absolute value of the gradient
that depends on the solution itself. The only required assumption on the
nonlinearity of this constraint is its continuity and positivity. The method
relies on an appropriate parabolic regularization and suitable {\em a priori}
estimates. We obtain also the existence of stationary solutions, by studying
the asymptotic behaviour in time. In the variational case, corresponding to a
constraint independent of the solution, we also give uniqueness results
Effects of reproduction and environmental factors on body temperature and activity patterns of wolverines
publishedVersio
Boron Isotope Effect in Superconducting MgB
We report the preparation method of, and boron isotope effect for MgB, a
new binary intermetallic superconductor with a remarkably high superconducting
transition temperature (B) = 40.2 K. Measurements of both
temperature dependent magnetization and specific heat reveal a 1.0 K shift in
between MgB and MgB. Whereas such a high transition
temperature might imply exotic coupling mechanisms, the boron isotope effect in
MgB is consistent with the material being a phonon-mediated BCS
superconductor.Comment: One figure and related discussion adde
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