2,597 research outputs found
Adjoints of elliptic cone operators
We study the adjointness problem for the closed extensions of a general
b-elliptic operator A in x^{-\nu}Diff^m_b(M;E), \nu>0, initially defined as an
unbounded operator A:C_c^\infty(M;E)\subset x^\mu L^2_b(M;E)\to x^\mu
L^2_b(M;E), \mu \in \R. The case where A is a symmetric semibounded operator is
of particular interest, and we give a complete description of the domain of the
Friedrichs extension of such an operator.Comment: 40 pages, LaTeX, preliminary versio
Currency Crises: Is Central America Different?
In a recent paper we analyzed the determinants of currency crises in a sample of 30 high and middle income countries (Esquivel and Larrain, 1998). In this work we focus on Central America and analyze whether the determinants of currency crises in this region are different from those identified in our previous work. We conclude that they are not, and show that a small set of macroeconomic variables helps to explain the currency crises that took place in Central America between 1976 and 1996. The results of tests applied here support the empirical approach that attempts to explain currency crises by focusing on the behavior of a few macroeconomic indicators. Part of the interest of this result stems from the fact that the Central American countries had an exchange rate system markedly different from that prevailing in the economies that are usually analyzed in similar studies.
THE IMPACT OF G-3 EXCHANGE RATE VOLATILITY ON DEVELOPING COUNTRIES,
This paper describes G-3 exchange rate volatility and evaluates its impact on developing countries. The paper presents empirical evidence showing that G-3 exchange rate volatility has a robust and significantly negative impact on developing countries’ exports. A one percentage point increase in G-3 exchange rate volatility decreases real exports of developing countries by about 2 per cent, on average. G-3 exchange rate volatility also appears to have a negative influence on foreign direct investment to certain regions, and increases the probability of occurrence of exchange rate crises in developing countries. These results imply that greater stability in the international exchange rate system would help improve trade and foreign direct investment prospects for developing countries – and would help prevent currency crises.
Strong Monogamy of Bipartite and Genuine Multipartite Entanglement: The Gaussian Case
We demonstrate the existence of general constraints on distributed quantum
correlations, which impose a trade-off on bipartite and multipartite
entanglement at once. For all N-mode Gaussian states under permutation
invariance, we establish exactly a monogamy inequality, stronger than the
traditional one, that by recursion defines a proper measure of genuine
N-partite entanglement. Strong monogamy holds as well for subsystems of
arbitrary size, and the emerging multipartite entanglement measure is found to
be scale invariant. We unveil its operational connection with the optimal
fidelity of continuous variable teleportation networks.Comment: 4 pages, 2 figures. Final version, published in PR
On the closure of elliptic wedge operators
We prove a semi-Fredholm theorem for the minimal extension of elliptic
operators on manifolds with wedge singularities and give, under suitable
assumptions, a full asymptotic expansion of the trace of the resolvent.Comment: 22 pages, improved expositio
Resolvents of elliptic cone operators
We prove the existence of sectors of minimal growth for general closed
extensions of elliptic cone operators under natural ellipticity conditions.
This is achieved by the construction of a suitable parametrix and reduction to
the boundary. Special attention is devoted to the clarification of the analytic
structure of the resolvent.Comment: 46 pages, submitted for publicatio
Trace expansions for elliptic cone operators with stationary domains
We analyze the behavior of the trace of the resolvent of an elliptic cone
differential operator as the spectral parameter tends to infinity. The
resolvent splits into two components, one associated with the minimal extension
of the operator, and another, of finite rank, depending on the particular
choice of domain. We give a full asymptotic expansion of the first component
and expand the component of finite rank in the case where the domain is
stationary. The results make use, and develop further, our previous
investigations on the analytic and geometric structure of the resolvent. The
analysis of nonstationary domains, considerably more intricate, is pursued
elsewhere.Comment: 27 pages. Minor corrections and change of titl
Simple proof of the robustness of Gaussian entanglement in bosonic noisy channels
The extremality of Gaussian states is exploited to show that Gaussian states
are the most robust, among all possible bipartite continuous-variable states at
fixed energy, against disentanglement due to noisy evolutions in Markovian
Gaussian channels involving dissipation and thermal hopping. This proves a
conjecture raised recently in [M. Allegra, P. Giorda, and M. G. A. Paris, Phys.
Rev. Lett. {\bf 105}, 100503 (2010)], providing a rigorous validation of the
conclusions of that work. The problem of identifying continuous variable states
with maximum resilience to entanglement damping in more general bosonic open
system dynamical evolutions, possibly including correlated noise and
non-Markovian effects, remains open.Comment: 3 pages, 1 figure, brief repor
Geometry and spectra of closed extensions of elliptic cone operators
We study the geometry of the set of closed extensions of index 0 of an
elliptic cone operator and its model operator in connection with the spectra of
the extensions, and give a necessary and sufficient condition for the existence
of rays of minimal growth for such operators.Comment: 48 pages, revisited version to appear in Canadian Journal of
Mathematic
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