275 research outputs found
Self energies of the pion and the delta isobar from the ^3He(e,e'pi^+)^3H reaction
In a kinematically complete experiment at the Mainz microtron MAMI, pion
angular distributions of the He(e,e'H reaction have been measured
in the excitation region of the resonance to determine the
longitudinal (), transverse (), and the interference part of the
differential cross section. The data are described only after introducing
self-energy modifications of the pion and -isobar propagators. Using
Chiral Perturbation Theory (ChPT) to extrapolate the pion self energy as
inferred from the measurement on the mass shell, we deduce a reduction of the
mass of MeV/c in the
neutron-rich nuclear medium at a density of fm. Our data are consistent with the self energy
determined from measurements of photoproduction from He and heavier
nuclei.Comment: Elsart, 12 pages and 4 figures, Correspondent: Professor Dr. Dr. h.c.
mult. Achim Richter, [email protected], submitted to Phys. Rev.
Let
Transition to turbulence in Taylor-Couette ferrofluidic flow
Y.D. was supported by Basic Science Research Program of the Ministry of Education, Science and Technology under Grant No. NRF-2013R1A1A2010067. Y.C.L. was supported by AFOSR under Grant No. FA9550-12-1-0095.Peer reviewedPublisher PD
Fully QED/relativistic theory of light pressure on free electrons by isotropic radiation
A relativistic/QED theory of light pressure on electrons by an isotropic, in
particular blackbody radiation predicts thermalization rates of free electrons
over entire span of energies available in the lab and the nature. The
calculations based on the QED Klein-Nishina theory of electron-photon
scattering and relativistic Fokker-Planck equation, show that the transition
from classical (Thompson) to QED (Compton) thermalization determined by the
product of electron energy and radiation temperature, is reachable under
conditions for controlled nuclear fusion, and predicts large acceleration of
electron thermalization in the Compton domain and strong damping of plasma
oscillations at the temperatures near plasma nuclear fusion.Comment: 9 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1410.695
A supply and demand model of bilateral trade in a multicountry framework
This study develops a practical supply and demand model of bilateral trade flows. The model is constructed in two tiers. First, aggregate import demand and aggregate export supply are determined from aggregate economic relations that contain real income (output) and relative prices. Second, bilateral import demand and bilateral export supply are determined from theory-based allocation relations. By differentiating import prices from export prices, the analysis incorporates international transportation costs and tariffs. The result is a simultaneous system that determines bilateral trade flows and bilateral prices given country incomes, domestic price levels and international transmission factors. The model in dynamic form is estimated from a panel of bilateral trade flows for five major OECD countries (United States, Japan, France, West Germany, United Kingdom) for the years 1958-1971. The model has many applications, e.g. in the analyses of the impacts on trade flows of differential economic growth rates and tariff policies. These policy aspects figure prominently in the current discussions among the major OECD countries.
A Method for Modeling Decoherence on a Quantum Information Processor
We develop and implement a method for modeling decoherence processes on an
N-dimensional quantum system that requires only an -dimensional quantum
environment and random classical fields. This model offers the advantage that
it may be implemented on small quantum information processors in order to
explore the intermediate regime between semiclassical and fully quantum models.
We consider in particular system-environment couplings which
induce coherence (phase) damping, though the model is directly extendable to
other coupling Hamiltonians. Effective, irreversible phase-damping of the
system is obtained by applying an additional stochastic Hamiltonian on the
environment alone, periodically redressing it and thereby irreversibliy
randomizing the system phase information that has leaked into the environment
as a result of the coupling. This model is exactly solvable in the case of
phase-damping, and we use this solution to describe the model's behavior in
some limiting cases. In the limit of small stochastic phase kicks the system's
coherence decays exponentially at a rate which increases linearly with the kick
frequency. In the case of strong kicks we observe an effective decoupling of
the system from the environment. We present a detailed implementation of the
method on an nuclear magnetic resonance quantum information processor.Comment: 12 pages, 9 figure
Konsensusprotokoll zur Standardisierung von Entnahme und Biobanking des Liquor cerebrospinalis
Die Erforschung von Biomarkern in Körperflüssigkeiten bei neurodegenerativen und neuroinflammatorischen Erkrankungen blickt auf eine langjährige Geschichte zurück. Dennoch werden nur wenige Liquor cerebrospinalis (Liquor)-Biomarker in der klinischen Praxis verwendet. Einer der problematischen Faktoren in der Liquorbiomarker-Forschung ist die eingeschränkte Aussagekraft von Studien aufgrund einer nicht ausreichend großer Anzahl von Proben, die in Studien von einzelnen Zentren akquiriert werden können. Deshalb ist die Kooperation zwischen mehreren Zentren erforderlich, um große Biobanken von definierten Proben zu etablieren. Standardisierte Protokolle für Biobanking sind unumgänglich, um die durch die größere Anzahl von Liquorproben gewonnene statistische Aussagekraft sicherzustellen und nicht durch mangelhafte Präanalytik einzuschränken. Hier wird ein Konsensusbericht über Leitlinien zu Liquorentnahme und Biobanking durch das BioMS-eu Netzwerk für Liquorbiomarker-Forschung in Multipler Sklerose präsentiert. Schwerpunkte des Berichts sind Liquorentnahme, präanalytische Faktoren und klinische sowie sonstige Informationen. Biobanking-Protokolle sind für Liquor-Biobanken im Rahmen der Erforschung jeder neurologischen Krankheit anwendba
Tabelas De Volume Para A Floresta De Terra Firme Da Estação Experimental De Silvicultura Tropical
The authors present, based on data from 235 trees, volume tables (with and without bark) for some tree species of economic value that occur at the Tropical Silviculture Experiment Station (EEST - at INPA). Three volumetric equations were tested. Schumacher's equation (V = a Db Hc) was found to give best statistical fit and was utilized to generate the tables.", 'enSão apresentadas as tabelas de volume para algumas espécies madeireiras que ocorrem na Estação Experimental de Silvicultura Tropical, com base em dados coletados de 235 árvores. Foram testadas três equações volumétricas. A equação de Schumacher (V = a Db HC) foi a que apresentou os melhores resultados estatísticos, sendo portanto o modelo gerador das tabelas
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