16,380 research outputs found
From Disordered Crystal to Glass: Exact Theory
We calculate thermodynamic properties of a disordered model insulator,
starting from the ideal simple-cubic lattice () and increasing the
disorder parameter to . As in earlier Einstein- and Debye-
approximations, there is a phase transition at . For the
low-T heat-capacity whereas for , . The van
Hove singularities disappear at {\em any finite }. For we discover
novel {\em fixed points} in the self-energy and spectral density of this model
glass.Comment: Submitted to Phys. Rev. Lett., 8 pages, 4 figure
Learning and training on the use of prescribed burning techniques
Many of the technicians who applied the technique of prescribed burning were forest and range managers, but they could also be fire fighters, among many other professions. We will use the term fire professional for all of those trained in fire. In our point of view, agreeing with Kobziar et al. (2009), fire professionals should have not only specific training on prescribed burning (professional/continuous training) and practical experience in the field, but also a good fire education (university courses). Following this premise, the objectives of this chapter are to: • Describe and assess the current context on prescribed burning training in Europe (Spain, Portugal and France); • Propose ways to continue the efforts to harmonise qualifications in Europe and to permanently exchange experiences on prescribed training; • Describe and assess the current situation with regard to forest education, university level in Europe (Spain and Portugal) and compare it to the US forest education; • Propose new ways for the example of an International Graduate Program in Fire Science and Management http://www.efi.int/files/attachments/publications/efi_rr23.pdfN/
Long-term Stellar Variability in the Galactic Centre Region
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.We report the detection of variable stars within a 11.5' x 11.5' region near the Galactic centre (GC) that includes the Arches and Quintuplet clusters, as revealed by the VISTA Variables in the Via Lactea (VVV) survey. There are 353 sources that show Ks-band variability, of which the large majority (81%) correspond to red giant stars, mostly in the asymptotic giant branch (AGB) phase. We analyze a population of 52 red giants with long-term trends that cannot be classified into the typical pulsating star categories. Distances and extinctions are calculated for 9 Mira variables, and we discuss the impact of the chosen extinction law on the derived distances. We also report the presence of 48 new identified young stellar object (YSO) candidates in the region.Peer reviewe
Stationary Localized States Due to a Nonlinear Dimeric Impurity Embedded in a Perfect 1-D Chain
The formation of Stationary Localized states due to a nonlinear dimeric
impurity embedded in a perfect 1-d chain is studied here using the appropriate
Discrete Nonlinear Schrdinger Equation. Furthermore, the nonlinearity
has the form, where is the complex amplitude. A proper
ansatz for the Localized state is introduced in the appropriate Hamiltonian of
the system to obtain the reduced effective Hamiltonian. The Hamiltonian
contains a parameter, which is the ratio of stationary
amplitudes at impurity sites. Relevant equations for Localized states are
obtained from the fixed point of the reduced dynamical system. = 1 is
always a permissible solution. We also find solutions for which . Complete phase diagram in the plane comprising of both
cases is discussed. Several critical lines separating various regions are
found. Maximum number of Localized states is found to be six. Furthermore, the
phase diagram continuously extrapolates from one region to the other. The
importance of our results in relation to solitonic solutions in a fully
nonlinear system is discussed.Comment: Seven figures are available on reques
The \rho\rho interaction in the hidden gauge formalism and the f_0(1370) and f_2(1270) resonances
We have studied the interaction of vectors mesons within the hidden gauge
formalism and applied it to the particular case of the interaction.
We find a strong attraction in the isospin, spin channels I,S=0,0 and 0,2,
which is enough to bind the system. We also find that the
attraction in the I,S=0,2 channel is much stronger than in the 0,0 case. The
states develop a width when the mass distribution is considered, and
particularly when the decay channel is turned on. Using a
regularization scheme with cut offs of natural size, we obtain results in fair
agreement with the mass and the width of the and meson
states, providing a natural explanation of why the tensor state is more bound
than the scalar and offering a new picture for these states, which would be
dynamically generated from the interaction or, in simpler words,
molecular states.Comment: Version accepted for publicatio
Embedding method for the scattering phase in strongly correlated quantum dots
The embedding method for the calculation of the conductance through
interacting systems connected to single channel leads is generalized to obtain
the full complex transmission amplitude that completely characterizes the
effective scattering matrix of the system at the Fermi energy. We calculate the
transmission amplitude as a function of the gate potential for simple
diamond-shaped lattice models of quantum dots with nearest neighbor
interactions. In our simple models we do not generally observe an interaction
dependent change in the number of zeroes or phase lapses that depend only on
the symmetry properties of the underlying lattice. Strong correlations separate
and reduce the widths of the resonant peaks while preserving the qualitative
properites of the scattering phase.Comment: 11 pages, 3 figures. Proceedings of the Workshop on Advanced
Many-Body and Statistical Methods in Mesoscopic Systems, Constanta, Romania,
June 27th - July 2nd 2011. To appear in Journal of Physics: Conference Serie
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