2,160 research outputs found
Ground State Properties of Anderson Impurity in a Gapless Host
Using the Bethe ansatz method, we study the ground state properties of a
Anderson impurity in a ``gapless'' host, where a density of band
states vanishes at the Fermi level as . As
in metals, the impurity spin is proven to be screened at arbitrary parameters
of the system. However, the impurity occupancy as a function of the bare
impurity energy is shown to acquire novel qualitative features which
demonstrate a nonuniversal behavior of the system. The latter explains why the
Kondo screening is absent (or exists only at quite a large electron-impurity
coupling) in earlier studies based on scaling arguments.Comment: 5 pages, no figure, RevTe
Exactly solvable toy models of unconventional magnetic alloys: Bethe Ansatz versus Renormalization Group method
We propose toy models of unconventional magnetic alloys, in which the density
of band states, , and hybridization, , are energy
dependent; it is assumed, however, that
, and hence an effective
electron-impurity coupling is
energy independent. In the renormalization group approach, the physics of the
system is assumed to be governed by only rather than by
separate forms of and . However, an exact Bethe
Ansatz solution of the toy Anderson model demonstrates a crucial role of a form
of inverse band dispersion .Comment: A final version. A previous one has been sent to Archive because of
my technical mistake. Sorr
Learning Behavioural Context
The original publication is available at www.springerlink.co
Polycystic ovary syndrome and leukocyte telomere length: cross-sectional and longitudinal changes
Peer reviewe
Energy efficiency parametric design tool in the framework of holistic ship design optimization
Recent International Maritime Organization (IMO) decisions with respect to measures to reduce the emissions from maritime greenhouse gases (GHGs) suggest that the collaboration of all major stakeholders of shipbuilding and ship operations is required to address this complex techno-economical and highly political problem efficiently. This calls eventually for the development of proper design, operational knowledge, and assessment tools for the energy-efficient design and operation of ships, as suggested by the Second IMO GHG Study (2009). This type of coordination of the efforts of many maritime stakeholders, with often conflicting professional interests but ultimately commonly aiming at optimal ship design and operation solutions, has been addressed within a methodology developed in the EU-funded Logistics-Based (LOGBASED) Design Project (2004–2007). Based on the knowledge base developed within this project, a new parametric design software tool (PDT) has been developed by the National Technical University of Athens, Ship Design Laboratory (NTUA-SDL), for implementing an energy efficiency design and management procedure. The PDT is an integral part of an earlier developed holistic ship design optimization approach by NTUA-SDL that addresses the multi-objective ship design optimization problem. It provides Pareto-optimum solutions and a complete mapping of the design space in a comprehensive way for the final assessment and decision by all the involved stakeholders. The application of the tool to the design of a large oil tanker and alternatively to container ships is elaborated in the presented paper
Sonically-enhanced widgets: comments on Brewster and Clarke, ICAD 1997
This paper presents a review of the research surrounding the paper “The Design and Evaluation of a Sonically Enhanced Tool Palette” by Brewster and Clarke from ICAD 1997. A historical perspective is given followed by a discussion of how this work has fed into current developments in the area
Kondo effect in a quantum critical ferromagnet
We study the Heisenberg ferromagnetic spin chain coupled with a boundary
impurity. Via Bethe ansatz solution, it is found that (i) for J>0, the impurity
spin behaves as a diamagnetic center and is completely screened by 2S bulk
spins in the ground state, no matter how large the impurity spin is; (ii) The
specific heat of the local composite (impurity plus 2S bulk spins which form
bound state with it) shows a simple power law . (iii)For
J<0, the impurity is locked into the critical behavior of the bulk. Possible
phenomena in higher dimensions are discussed.Comment: 6page Revtex, no figure, final version in PRB, Jun 1 issue, 199
The Molonglo Galactic Plane Survey: I. Overview and Images
The first epoch Molonglo Galactic Plane Survey (MGPS1) is a radio continuum
survey made using the Molonglo Observatory Synthesis Telescope (MOST) at 843
MHz with a resolution of 43" X 43" cosec |delta|. The region surveyed is 245
deg < l < 355 deg, |b| < 1.5 deg. The thirteen 9 deg X 3 deg mosaic images
presented here are the superposition of over 450 complete synthesis
observations, each taking 12 h and covering 70' X 70' cosec |delta|. The
root-mean-square sensitivity over much of the mosaiced survey is 1-2 mJy/beam
(1 sigma), and the positional accuracy is approximately 1" X 1" cosec |delta|
for sources brighter than 20 mJy. The dynamic range is no better than 250:1,
and this also constrains the sensitivity in some parts of the images. The
survey area of 330 sq deg contains well over 12,000 unresolved or barely
resolved objects, almost all of which are extra-galactic sources lying in the
Zone of Avoidance. In addition a significant fraction of this area is covered
by extended, diffuse emission associated with thermal complexes, discrete H II
regions, supernova remnants, and other structures in the Galactic interstellar
medium.Comment: Paper with 3 figures and 1 table + Table 2 + 7 jpg grayscales for Fig
4. Astrophysical Journal Supplement (in press) see also
http://www.astrop.physics.usyd.edu.au/MGP
Absence of overscreened Kondo effect in ferromagnetic host
We study the low temperature behavior of a boundary magnetic impurity S'=1/2
in an open ferromagnetic Takhatajian-Babujian spin-S chain. For
antiferromagnetic Kondo coupling, it is show via Bethe ansatz solution that the
impurity spin is always locked into the critical behavior the bulk. At low
temperature, a local composite of spin S-1/2 forms near the impurity site and
its contribution to specific heat is of simple power law T^{1/2}. The absence
of overscreened Kondo effect is due to the large correlation length of host
spins which is divergent near the quantum critical point.Comment: 4 pages. to appear in Phys. Rev. B1(R4A)(2000
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