4,149 research outputs found
Development of an Organic Table Grape Production and Market in Switzerland
In Switzerland there is an increasing consumer demand for residue-free, organic table
grapes. The organic cultivation of table grapes, however, is very delicate in humid climates
and experience to advice organic growers is still lacking. The goal of our project that has
started in 2004 is to develop and establish a cultivation system for organic table grapes
under Swiss climatic and economic conditions with a high yield security and fulfilling the
high quality demands of the market. Preliminary results: Interesting cultivars to produce
are e.g. Fanny, Lilla, Palatina. However they are disease susceptible and must be
produced under a rain roof. Better suited cultivars still need to be found. Consumer
acceptance for organic table grapes produced in Switzerland is very positive. However
changes towards new cultivars and lower production costs are necessary. Spray programs
to achieve sufficient disease protection and no spray blotch seem to be realizable, mainly
for production under rain roof
Measurement of the spatial extent of inverse proximity in a Py/Nb/Py superconducting trilayer using low-energy muon-spin rotation
The authors acknowledge the financial support of the EPSRC (Grant No. EP/J01060X).Muon-spin rotation has been used to observe directly the spatial variation of the magnetic flux density near the ferromagnetic-superconducting interface in a permalloy-niobium trilayer. Above the superconducting transition temperature Tc the profile of the induced magnetic flux density within the niobium layer has been determined. Below Tc there is a significant reduction of the induced flux density, predominantly near the ferromagnetic-superconducting interfaces. We are uniquely able to determine the magnitude and spatial variation of this reduction in induced magnetization due to the presence of the Cooper pairs, yielding the magnitude and length scale associated with this phenomenon. Both are inconsistent with a simple Meissner screening and indicate the existence of another mechanism, the influence of which is localized within the vicinity of the ferromagnetic interface.Publisher PDFPeer reviewe
Advanced liquid oxygen (LO2) propellant conditioning concept testing
Advanced methods of liquid oxygen (LO2) propellant conditioning were studied as part of an effort for increasing reliability and operability while reducing cost of future heavy lift launch vehicles. The most promising conditioning concept evaluated was no-bleed (passive recirculation) followed by low-bleed, helium injection, and use of a recirculation line. Full-scale cryogenic testing was performed with a sloped feedline test article to validate models of behavior of LO2 in the feedline and to prove no-bleed feasibility. Test data are also intended to help generate design guidelines for the development of a main propulsion system feed duct. A design-of-experiments matrix of over 100 tests was developed to test all four propellant conditioning concepts and the impact of design parameters on the concepts. Liquid nitrogen was used as the test fluid. The work for this project was conducted from October 1992 through January 1994 at the hydrogen cold flow facility of the west test area of MSFC. Test data have shown that satisfactory temperatures are being obtained for the no-bleed conditioning concept
Quantum affine Cartan matrices, Poincare series of binary polyhedral groups, and reflection representations
We first review some invariant theoretic results about the finite subgroups
of SU(2) in a quick algebraic way by using the McKay correspondence and quantum
affine Cartan matrices. By the way it turns out that some parameters
(a,b,h;p,q,r) that one usually associates with such a group and hence with a
simply-laced Coxeter-Dynkin diagram have a meaningful definition for the
non-simply-laced diagrams, too, and as a byproduct we extend Saito's formula
for the determinant of the Cartan matrix to all cases. Returning to invariant
theory we show that for each irreducible representation i of a binary
tetrahedral, octahedral, or icosahedral group one can find a homomorphism into
a finite complex reflection group whose defining reflection representation
restricts to i.Comment: 19 page
Toward an integrated approach to perception and action: conference report and future directions
This article was motivated by the conference entitled āPerception & Action ā An Interdisciplinary Approach to Cognitive Systems Theory,ā which took place September 14ā16, 2010 at the Santa Fe Institute, NM, USA. The goal of the conference was to bring together an interdisciplinary group of neuroscientists, roboticists, and theorists to discuss the extent and implications of actionāperception integration in the brain. The motivation for the conference was the realization that it is a widespread approach in biological, theoretical, and computational neuroscience to investigate sensory and motor function of the brain in isolation from one another, while at the same time, it is generally appreciated that sensory and motor processing cannot be fully separated. Our article summarizes the key findings of the conference, provides a hypothetical model that integrates the major themes and concepts presented at the conference, and concludes with a perspective on future challenges in the field
Realization of logically labeled effective pure states for bulk quantum computation
We report the first use of "logical labeling" to perform a quantum
computation with a room-temperature bulk system. This method entails the
selection of a subsystem which behaves as if it were at zero temperature -
except for a decrease in signal strength - conditioned upon the state of the
remaining system. No averaging over differently prepared molecules is required.
In order to test this concept, we execute a quantum search algorithm in a
subspace of two nuclear spins, labeled by a third spin, using solution nuclear
magnetic resonance (NMR), and employing a novel choice of reference frame to
uncouple nuclei.Comment: PRL 83, 3085 (1999). Small changes made to improve readability and
remove ambiguitie
The Quantum Adiabatic Approximation and the Geometric Phase
A precise definition of an adiabaticity parameter of a time-dependent
Hamiltonian is proposed. A variation of the time-dependent perturbation theory
is presented which yields a series expansion of the evolution operator
with being at least of
the order . In particular corresponds to the
adiabatic approximation and yields Berry's adiabatic phase. It is shown that
this series expansion has nothing to do with the -expansion of
. It is also shown that the non-adiabatic part of the evolution
operator is generated by a transformed Hamiltonian which is off-diagonal in the
eigenbasis of the initial Hamiltonian. Some related issues concerning the
geometric phase are also discussed.Comment: uuencoded LaTeX file, 19 page
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