34,737 research outputs found
Selection of winter cereals for organic agriculture
Productivity in agriculture has more than tripled in developed countries since the 1950s. Beyond the success of plant breeding, the increased use of inorganic fertilizers, application of pesticides, and spread of irrigation also contributed to this success. However, impressive yield increases started to decline in the 1980s because of the lack of sustainability.
One of the most beneficial ways to increase sustainability is organic agriculture. In such systems the prerequisite of successful farming is the availability of crop genotypes that perform well. However, selection of winter cereals for sub-optimal growing conditions is still neglected, and the organic seed market also lacks of information on credibly tested varieties suitable for organic agriculture
The identification of wheat genetic resources with high dietary fiber content
The quality properties of different variety mixtures and composite cross populations were studied with the aim of identifying genotypes with high dietary fiber content and to cultivate and examine the effect of these components on the end-use quality. Based on the results of a Europe-wide trial, we could detect two populations and variety mixtures which had significantly higher total (TOTAX) and water extractable arabinoxylan (WEAX) content, than most of the studied genotypes, with positive effect on the human health. These populations/mixtures are promising dietary fiber resources and suitable not only for organic but also for conventional farming, especially in Central Europe. The seeds of the best population (Mv Elit CCP) was multiplied to supply it for interested farmers in Hungary in the frame of the European trial on organic heterogeneous materials
Evidence for Lattice Effects at the Charge-Ordering Transition in (TMTTF)X
High-resolution thermal expansion measurements have been performed for
exploring the mysterious "structureless transition" in (TMTTF)X (X =
PF and AsF), where charge ordering at coincides with the
onset of ferroelectric order. Particularly distinct lattice effects are found
at in the uniaxial expansivity along the interstack
-direction. We propose a scheme involving a charge
modulation along the TMTTF stacks and its coupling to displacements of the
counteranions X. These anion shifts, which lift the inversion symmetry
enabling ferroelectric order to develop, determine the 3D charge pattern
without ambiguity. Evidence is found for another anomaly for both materials at
0.6 indicative of a phase transition
related to the charge ordering
Isospin-projected nuclear level densities by the shell model Monte Carlo method
We have developed an efficient isospin projection method in the shell model
Monte Carlo approach for isospin-conserving Hamiltonians. For isoscalar
observables this projection method has the advantage of being exact sample by
sample. The isospin projection method allows us to take into account the proper
isospin dependence of the nuclear interaction, thus avoiding a sign problem
that such an interaction introduces in unprojected calculations. We apply our
method in the calculation of the isospin dependence of level densities in the
complete shell. We find that isospin-dependent corrections to the
total level density are particularly important for nuclei.Comment: 5 pages including 4 figure
Towards the Green-Griffiths-Lang conjecture
The Green-Griffiths-Lang conjecture stipulates that for every projective
variety X of general type over C, there exists a proper algebraic subvariety of
X containing all non constant entire curves f : C X. Using the
formalism of directed varieties, we prove here that this assertion holds true
in case X satisfies a strong general type condition that is related to a
certain jet-semistability property of the tangent bundle TX . We then give a
sufficient criterion for the Kobayashi hyperbolicity of an arbitrary directed
variety (X,V). This work is dedicated to the memory of Professor Salah
Baouendi.Comment: version 2 has been expanded and improved (15 pages
The anomaly-free quantization of two-dimensional relativistic string. I
An anomaly-free quantum theory of a relativistic string is constructed in
two-dimensional space-time. The states of the string are found to be similar to
the states of a massless chiral quantum particle. This result is obtained by
generalizing the concept of an ``operator'' in quantum field theory.Comment: LaTeX, 19 pages, no figure
Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy
Using time-domain Terahertz spectroscopy we performed direct studies of the
photoinduced suppression and recovery of the superconducting gap in a
conventional BCS superconductor NbN. Both processes are found to be strongly
temperature and excitation density dependent. The analysis of the data with the
established phenomenological Rothwarf-Taylor model enabled us to determine the
bare quasiparticle recombination rate, the Cooper pair-breaking rate and the
electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent
agreement with theoretical estimates.Comment: 4 pages, 4 figures; final version, accepted for publication in Phys.
Rev. Let
Coexisting periodic attractors in injection locked diode lasers
We present experimental evidence for coexisting periodic attractors in a
semiconductor laser subject to external optical injection. The coexisting
attractors appear after the semiconductor laser has undergone a Hopf
bifurcation from the locked steady state. We consider the single mode rate
equations and derive a third order differential equation for the phase of the
laser field. We then analyze the bifurcation diagram of the time periodic
states in terms of the frequency detuning and the injection rate and show the
existence of multiple periodic attractors.Comment: LaTex, 14 pages, 6 postscript figures include
Ferroelectric properties of charge-ordered alpha-(BEDT-TTF)2I3
A detailed investigation of the out-of-plane electrical properties of
charge-ordered alpha-(BEDT-TTF)2I3 provides clear evidence for
ferroelectricity. Similar to multiferroic alpha-(BEDT-TTF)2Cu[N(CN)2]Cl, the
polar order in this material is ascribed to the occurrence of bond- and
site-centered charge order. Dielectric response typical for relaxor
ferroelectricity is found deep in the charge-ordered state. We suggest an
explanation in terms of the existence of polar and nonpolar stacks of the
organic molecules in this material, preventing long-range ferroelectricity. The
results are discussed in relation to the formation or absence of electronic
polar order in related charge-transfer salts.Comment: 8 pages, 4 figures. Revised version as accepted for publication in
Phys. Rev.
Modular differential equations for torus one-point functions
It is shown that in a rational conformal field theory every torus one-point
function of a given highest weight state satisfies a modular differential
equation. We derive and solve these differential equations explicitly for some
Virasoro minimal models. In general, however, the resulting amplitudes do not
seem to be expressible in terms of standard transcendental functions.Comment: 19 pages, LaTeX; reference adde
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