891 research outputs found
Arbeitsnetz zur Weiterentwicklung der Anbaukonzepte im Ökologischen Obstbau
Im Rahmen des Projektes ist eine Schwachstellenanalyse der Anbaukonzepte des ökologischen Obstbaus gefolgt von einer Erarbeitung von kurz- und langfristig umsetzbaren fundierten und praxisnahen Strategieansätzen zur Optimierung dieser Konzepte in enger Vernetzung von Praxisbetrieben, Beratung, angewandter Forschung und Grundlagenforschung sowie fachspezifischer Experten erfolgt. Das bundesweite Diskussionsforum aus Praktikern, Berater und Forschern, das zur laufenden Weiterentwicklung der Anbaumethoden geschaffen wurde, ist inzwischen eingespielt, arbeitet effizient und richtungsweisend. Dadurch werden laufenden Arbeiten zu verschiedenen Fragen optimal begleitet. Neu auftretende Fragen können rasch aufgegriffen und bearbeitet werden. Diese Form der Weiterentwicklung entspricht der ursprünglichen Struktur, die den Ökologischen Landbau hervorgebracht hat.
Für die wichtigsten ungelösten Problembereiche (Apfelwickler, Schorf, Regenflecken, Feuerbrand) konnten sehr effizient aus der Praxis heraus Strategien für Lösungsansätze erarbeitet und in Form von Projekten umgesetzt werden. Stein- und Beerenobst waren vor Beginn des Arbeitsnetzes stark vernachlässigte Bereiche. Durch die Aktivitäten im Arbeitsnetz wurden hier erstmals Schwachstellen erkannt und Handlungsbedarf formuliert. Aus dieser Arbeit sind Projektanträge sowohl im Stein- als auch im Beerenobst hervorgegangen, die die ermittelten Schwachstellen bearbeiten und in Zusammenarbeit mit der Praxis umsetzen sollen. In beiden Kulturen haben sich außerdem Aktivitäten etabliert, die in Zusammenarbeit mit den Versuchsanstalten und Züchtern eine Prüfung neuer Sorten unter ökologischen Anbaubedingungen in den Betrieben ermöglichen sollen. Für Kernobst wurde im Jahr 2005 ein Sorteninformationsnetz gegründet. Strategieansätze wurden aber nicht nur für eine Optimierung der Wirtschaftlichkeit sondern auch der Nachhaltigkeit der Anbaukonzepte erarbeitet. So wurden erste Konzepte für eine ökologische Aufwertung von Obstanlagen angedacht, die derzeit in einigen Praxisbetrieben getestet werden.
Durch die Diskussion der Strategieansätze der einzelnen AKs im Rahmen der jährlichen Veranstaltung mit den Praktikern ergibt sich die Möglichkeit zur interdisziplinären Verknüpfung einzelner Projektergebnisse zu einem praxistauglichen Gesamtkonzept. Die Arbeit im Arbeitsnetz hat daher entscheidend dazu beigetragen, den ökologischen Obstbau sicherer, wirtschaftlicher und nachhaltiger zu gestalten
Selective laser ionization of N 82 indium isotopes: the new r-process nuclide In
Production yields and beta-decay half-lives of very neutron-rich indium isotopes were determined at CERN/ISOLDE using isobaric selectivity of a resonance-ionization laser ion-source. Beta-delayed neutron multiscaling measurements have yielded improved half-lives for 206(6)~ms In, 165(3)~ms In and 141(5)~ms In. With 92(10)~ms In, a new r-process nuclide has been identified which acts as an important `waiting-point' in the In isotopic chain for neutron densities in the range n--10 n/cm, where the r-matter flow has already passed the abundance-peak region
On least-order flow representations for aerodynamics and aeroacoustics
We propose a generalization of proper orthogonal decomposition (POD) for optimal flow resolution of linearly related observables. This Galerkin expansion, termed ‘observable inferred decomposition' (OID), addresses a need in aerodynamic and aeroacoustic applications by identifying the modes contributing most to these observables. Thus, OID constitutes a building block for physical understanding, least-biased conditional sampling, state estimation and control design. From a continuum of OID versions, two variants are tailored for purposes of observer and control design, respectively. Firstly, the most probable flow state consistent with the observable is constructed by a ‘least-residual' variant. This version constitutes a simple, easily generalizable reconstruction of the most probable hydrodynamic state to preprocess efficient observer design. Secondly, the ‘least-energetic' variant identifies modes with the largest gain for the observable. This version is a building block for Lyapunov control design. The efficient dimension reduction of OID as compared to POD is demonstrated for several shear flows. In particular, three aerodynamic and aeroacoustic goal functionals are studied: (i)lift and drag fluctuation of a two-dimensional cylinder wake flow; (ii)aeroacoustic density fluctuations measured by a sensor array and emitted from a two-dimensional compressible mixing layer; and (iii)aeroacoustic pressure monitored by a sensor array and emitted from a three-dimensional compressible jet. The most ‘drag-related', ‘lift-related' and ‘loud' structures are distilled and interpreted in terms of known physical processe
The s Process: Nuclear Physics, Stellar Models, Observations
Nucleosynthesis in the s process takes place in the He burning layers of low
mass AGB stars and during the He and C burning phases of massive stars. The s
process contributes about half of the element abundances between Cu and Bi in
solar system material. Depending on stellar mass and metallicity the resulting
s-abundance patterns exhibit characteristic features, which provide
comprehensive information for our understanding of the stellar life cycle and
for the chemical evolution of galaxies. The rapidly growing body of detailed
abundance observations, in particular for AGB and post-AGB stars, for objects
in binary systems, and for the very faint metal-poor population represents
exciting challenges and constraints for stellar model calculations. Based on
updated and improved nuclear physics data for the s-process reaction network,
current models are aiming at ab initio solution for the stellar physics related
to convection and mixing processes. Progress in the intimately related areas of
observations, nuclear and atomic physics, and stellar modeling is reviewed and
the corresponding interplay is illustrated by the general abundance patterns of
the elements beyond iron and by the effect of sensitive branching points along
the s-process path. The strong variations of the s-process efficiency with
metallicity bear also interesting consequences for Galactic chemical evolution.Comment: 53 pages, 20 figures, 3 tables; Reviews of Modern Physics, accepte
High-resolution measurement of the time-modulated orbital electron capture and of the decay of hydrogen-like Pm ions
The periodic time modulations, found recently in the two-body orbital
electron-capture (EC) decay of both, hydrogen-like Pr and
Pm ions, with periods near to 7s and amplitudes of about 20%,
were re-investigated for the case of Pm by using a 245 MHz
resonator cavity with a much improved sensitivity and time resolution. We
observed that the exponential EC decay is modulated with a period s, in accordance with a modulation period s as obtained
from simultaneous observations with a capacitive pick-up, employed also in the
previous experiments. The modulation amplitudes amount to and
for the 245 MHz resonator and the capacitive pick-up,
respectively. These new results corroborate for both detectors {\it exactly}
our previous findings of modulation periods near to 7s, though with {\it
distinctly smaller} amplitudes. Also the three-body decays have been
analyzed. For a supposed modulation period near to 7s we found an amplitude , compatible with and in agreement with the preliminary
result of our previous experiment. These observations could
point at weak interaction as origin of the observed 7s-modulation of the EC
decay. Furthermore, the data suggest that interference terms occur in the
two-body EC decay, although the neutrinos are not directly observed.Comment: In memoriam of Prof. Paul Kienle, 9 pages, 1 table, 5 figures Phys.
Lett. B (2013) onlin
Exactly Solvable Models: The Road Towards a Rigorous Treatment of Phase Transitions in Finite Systems
We discuss exact analytical solutions of a variety of statistical models
recently obtained for finite systems by a novel powerful mathematical method,
the Laplace-Fourier transform. Among them are a constrained version of the
statistical multifragmentation model, the Gas of Bags Model and the Hills and
Dales Model of surface partition. Thus, the Laplace-Fourier transform allows
one to study the nuclear matter equation of state, the equation of state of
hadronic and quark gluon matter and surface partitions on the same footing. A
complete analysis of the isobaric partition singularities of these models is
done for finite systems. The developed formalism allows us, for the first time,
to exactly define the finite volume analogs of gaseous, liquid and mixed phases
of these models from the first principles of statistical mechanics and
demonstrate the pitfalls of earlier works. The found solutions may be used for
building up a new theoretical apparatus to rigorously study phase transitions
in finite systems. The strategic directions of future research opened by these
exact results are also discussed.Comment: Contribution to the ``World Consensus Initiative III, Texas A & M
University, College Station, Texas, USA, February 11-17, 2005, 21
Neutron Thermal Cross Sections, Westcott Factors, Resonance Integrals, Maxwellian Averaged Cross Sections and Astrophysical Reaction Rates Calculated from Major Evaluated Data Libraries
We present calculations of neutron thermal cross sections, Westcott factors,
resonance integrals, Maxwellian-averaged cross sections and astrophysical
reaction rates for 843 ENDF materials using data from the major evaluated
nuclear libraries and European activation file. Extensive analysis of
newly-evaluated neutron reaction cross sections, neutron covariances, and
improvements in data processing techniques motivated us to calculate nuclear
industry and neutron physics quantities, produce s-process Maxwellian-averaged
cross sections and astrophysical reaction rates, systematically calculate
uncertainties, and provide additional insights on currently available
neutron-induced reaction data. Nuclear reaction calculations are discussed and
new results are presented.Comment: 145 pages, 15 figures, 19 table
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