5,192 research outputs found
European Economic Integration and the Consequences for U.S. Agriculture
The pace of political-economic change in former East Bloc nations of Europe defies accurate prediction. Some events such as more price-directed markets are predictable enough but integration of former East Bloc countries into the European Community remains a matter of speculation. Analysis indicates that the economics of agriculture favors acceptance by the European Community of members of the European Free Trade Association before former members of the. East Bloc. Analysis also indicates the considerable agricultural production potential of Central and East Europe will be unleased first by market-directed economies and later by integration with the EC -- if the latter occurs. US consumers gain more than producers lose so the economic welfare of Americans is raised modestly.International Relations/Trade,
Serial Verbs in the Creole Languages
Contains fulltext :
3835.pdf (publisher's version ) (Open Access
From Classical to Quantum Mechanics: "How to translate physical ideas into mathematical language"
In this paper, we investigate the connection between Classical and Quantum
Mechanics by dividing Quantum Theory in two parts: - General Quantum Axiomatics
(a system is described by a state in a Hilbert space, observables are
self-adjoint operators and so on) - Quantum Mechanics properly that specifies
the Hilbert space, the Heisenberg rule, the free Hamiltonian... We show that
General Quantum Axiomatics (up to a supplementary "axiom of classicity") can be
used as a non-standard mathematical ground to formulate all the ideas and
equations of ordinary Classical Statistical Mechanics. So the question of a
"true quantization" with "h" must be seen as an independent problem not
directly related with quantum formalism. Moreover, this non-standard
formulation of Classical Mechanics exhibits a new kind of operation with no
classical counterpart: this operation is related to the "quantization process",
and we show why quantization physically depends on group theory (Galileo
group). This analytical procedure of quantization replaces the "correspondence
principle" (or canonical quantization) and allows to map Classical Mechanics
into Quantum Mechanics, giving all operators of Quantum Mechanics and
Schrodinger equation. Moreover spins for particles are naturally generated,
including an approximation of their interaction with magnetic fields. We find
also that this approach gives a natural semi-classical formalism: some exact
quantum results are obtained only using classical-like formula. So this
procedure has the nice property of enlightening in a more comprehensible way
both logical and analytical connection between classical and quantum pictures.Comment: 47 page
Forecasting Cross-Sections of Frailty-Correlated Default
We propose a novel econometric model for estimating and forecasting cross-sections of time-varying conditional default probabilities. The model captures the systematic variation in corporate default counts across e.g. rating and industry groups by using dynamic factors from a large panel of selected macroeconomic and financial data as well as common unobserved risk factors. All factors are statistically and economically significant and together capture a large part of the time-variation in observed default rates. In this framework we improve the out-of-sample forecasting accuracy associated with conditional default probabilities by about 10-35 % in terms of Mean Absolute Error, particularly in years of default stress
Macro, industry and frailty effects in defaults: The 2008 credit crisis in perspective
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Chaos and quantum-nondemolition measurements
The problem of chaotic behavior in quantum mechanics is investigated against the background of the theory of quantum-nondemolition (QND) measurements. The analysis is based on two relevant features: The outcomes of a sequence of QND measurements are unambiguously predictable, and these measurements actually can be performed on one single system without perturbing its time evolution. Consequently, QND measurements represent an appropriate framework to analyze the conditions for the occurrence of ‘‘deterministic randomness’’ in quantum systems. The general arguments are illustrated by a discussion of a quantum system with a time evolution that possesses nonvanishing algorithmic complexity
Magnetic Sensitivity of AlMn TESes and Shielding Considerations for Next-Generation CMB Surveys
In the next decade, new ground-based Cosmic Microwave Background (CMB)
experiments such as Simons Observatory (SO), CCAT-prime, and CMB-S4 will
increase the number of detectors observing the CMB by an order of magnitude or
more, dramatically improving our understanding of cosmology and astrophysics.
These projects will deploy receivers with as many as hundreds of thousands of
transition edge sensor (TES) bolometers coupled to Superconducting Quantum
Interference Device (SQUID)-based readout systems. It is well known that
superconducting devices such as TESes and SQUIDs are sensitive to magnetic
fields. However, the effects of magnetic fields on TESes are not easily
predicted due to the complex behavior of the superconducting transition, which
motivates direct measurements of the magnetic sensitivity of these devices. We
present comparative four-lead measurements of the critical temperature versus
applied magnetic field of AlMn TESes varying in geometry, doping, and leg
length, including Advanced ACT (AdvACT) and POLARBEAR-2/Simons Array
bolometers. Molybdenum-copper bilayer ACTPol TESes are also tested and are
found to be more sensitive to magnetic fields than the AlMn devices. We present
an observation of weak-link-like behavior in AlMn TESes at low critical
currents. We also compare measurements of magnetic sensitivity for time
division multiplexing SQUIDs and frequency division multiplexing microwave
rf-SQUIDs. We discuss the implications of our measurements on the magnetic
shielding required for future experiments that aim to map the CMB to
near-fundamental limits.Comment: 8 pages, 4 figures, conference proceedings submitted to the Journal
of Low Temperature Physic
Complementarity in classical dynamical systems
The concept of complementarity, originally defined for non-commuting
observables of quantum systems with states of non-vanishing dispersion, is
extended to classical dynamical systems with a partitioned phase space.
Interpreting partitions in terms of ensembles of epistemic states (symbols)
with corresponding classical observables, it is shown that such observables are
complementary to each other with respect to particular partitions unless those
partitions are generating. This explains why symbolic descriptions based on an
\emph{ad hoc} partition of an underlying phase space description should
generally be expected to be incompatible. Related approaches with different
background and different objectives are discussed.Comment: 18 pages, no figure
Mass singularity and confining property in
We discuss the properties of the position space fermion propagator in three
dimensional QED which has been found previouly based on Ward-Takahashi-identity
for soft-photon emission vertex and spectral representation.There is a new type
of mass singularity which governs the long distance behaviour.It leads the
propagator vanish at large distance.This term corresponds to dynamical mass in
position space.Our model shows confining property and dynamical mass generation
for arbitrary coupling constant.Since we used dispersion retation in deriving
spectral function there is a physical mass which sets a mass scale.For finite
cut off we obtain the full propagator in the dispersion integral as a
superposition of different massses.Low energy behaviour of the proagator is
modified to decrease by position dependent mass.In the limit of zero infrared
cut-off the propagator vanishes with a new kind of infrared behaviour.Comment: 22pages,4figures,revtex4,Notational sloppiness are crrected.Submitted
to JHE
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