2,415 research outputs found
Excavations at Tas-Silg, 1996
For the first time ever, the Department of Classics and
Archaeology of the University of Malta conducted its
own excavations at the site of Tas-Silg which is located
at Marsaxlokk in the south-east of the island of Malta.
These excavations were directed by the authors, who
would like to thank Mr Simon Mason and Mr Nicholas
Vella who were responsible for the field supervision.
We would also like to thank the area supervisors,
namely Mr Andrew Appleyard, Ms Carmen Michelle
'Buhagiar, Ms Aloisia de Trafford, Mr Joseph Magro
Conti, Mr Paul C. Saliba as well as Mr Andre Corrado;
the latter agreed to act as an area supervisor for a while
when the need arose. Obviously, we do also appreciate
very much all the hard work of the "diggers" who were
in fact students from.the aforementioned Department
of Classics and Archaeology, the foreign and local
students who formed part of the first Summer School
in Archaeology which was organized by the
International Office of the University of Malta, and
some very eager and hard-working volunteers.peer-reviewe
Dynamic asset trees and Black Monday
The minimum spanning tree, based on the concept of ultrametricity, is
constructed from the correlation matrix of stock returns. The dynamics of this
asset tree can be characterised by its normalised length and the mean
occupation layer, as measured from an appropriately chosen centre called the
`central node'. We show how the tree length shrinks during a stock market
crisis, Black Monday in this case, and how a strong reconfiguration takes
place, resulting in topological shrinking of the tree.Comment: 6 pages, 3 eps figues. Elsevier style. Will appear in Physica A as
part of the Bali conference proceedings, in pres
Cosmological Perturbations in Renormalization Group Derived Cosmologies
A linear cosmological perturbation theory of an almost homogeneous and
isotropic perfect fluid Universe with dynamically evolving Newton constant
and cosmological constant is presented. A gauge-invariant formalism
is developed by means of the covariant approach, and the acoustic propagation
equations governing the evolution of the comoving fractional spatial gradients
of the matter density, , and are thus obtained. Explicit solutions
are discussed in cosmologies where both and vary according to
renormalization group equations in the vicinity of a fixed point.Comment: 22 pages, revtex, subeqn.sty, to appear on IJMP
Dynamical System Analysis of Cosmologies with Running Cosmological Constant from Quantum Einstein Gravity
We discuss a mechanism that induces a time-dependent vacuum energy on
cosmological scales. It is based on the instability induced renormalization
triggered by the low energy quantum fluctuations in a Universe with a positive
cosmological constant. We employ the dynamical systems approach to study the
qualitative behavior of Friedmann-Robertson-Walker cosmologies where the
cosmological constant is dynamically evolving according with this
nonperturbative scaling at low energies. It will be shown that it is possible
to realize a "two regimes" dark energy phases, where an unstable early phase of
power-law evolution of the scale factor is followed by an accelerated expansion
era at late times.Comment: 26 pages, 4 figures. To appear in New Journal of Physic
Flow Equations for U_k and Z_k
By considering the gradient expansion for the wilsonian effective action S_k
of a single component scalar field theory truncated to the first two terms, the
potential U_k and the kinetic term Z_k, I show that the recent claim that
different expansion of the fluctuation determinant give rise to different
renormalization group equations for Z_k is incorrect. The correct procedure to
derive this equation is presented and the set of coupled differential equations
for U_k and Z_k is definitely established.Comment: 5 page
- …