12,951 research outputs found
Fearless Friday: Jasmine Matos
This week Surge is honored to highlight Jasmine Matos for Fearless Friday!
Originally from the Bronx in NYC, Jasmine is here at Gettysburg majoring in Health Sciences and minoring in Women, Gender, and Sexuality Studies. She now finds herself in her last semester at Gettysburg College and is trying to make the most of it. She’s the Captain of B.O.M.B. Squad, a member of the Black Student Union (BSU), a member of the Latin American Student Association (LASA), and she works in the Admissions Office. [excerpt
Generalized Gross--Perry--Sorkin--Like Solitons
In this paper, we present a new solution for the effective theory of
Maxwell--Einstein--Dilaton, Low energy string and Kaluza--Klein theories, which
contains among other solutions the well known Kaluza--Klein monopole solution
of Gross--Perry--Sorkin as special case. We show also the magnetic and electric
dipole solutions contained in the general one.Comment: 10 latex pages, no figures. To appear in Class. Quant. Gravity
Rotating 5D-Kaluza-Klein Space-Times from Invariant Transformations
Using invariant transformations of the five-dimensional Kaluza-Klein (KK)
field equations, we find a series of formulae to derive axial symmetric
stationary exact solutions of the KK theory starting from static ones. The
procedure presented in this work allows to derive new exact solutions up to
very simple integrations. Among other results, we find exact rotating solutions
containing magnetic monopoles, dipoles, quadripoles, etc., coupled to scalar
and to gravitational multipole fields.Comment: 24 pages, latex, no figures. To appear in Gen. Rel. Grav., 32,
(2000), in pres
On the Space Time of a Galaxy
We present an exact solution of the averaged Einstein's field equations in
the presence of two real scalar fields and a component of dust with spherical
symmetry. We suggest that the space-time found provides the characteristics
required by a galactic model that could explain the supermassive central object
and the dark matter halo at once, since one of the fields constitutes a central
oscillaton surrounded by the dust and the other scalar field distributes far
from the coordinate center and can be interpreted as a halo. We show the
behavior of the rotation curves all along the background. Thus, the solution
could be a first approximation of a ``long exposition photograph'' of a galaxy.Comment: 8 pages REVTeX, 11 eps figure
Social Requirements for Virtual Organization Breeding Environments
The creation of Virtual Breeding Environments (VBE) is a topic which has
received too little attention: in most former works, the existence of the VBE
is either assumed, or is considered as the result of the voluntary,
participatory gathering of a set of candidate companies. In this paper, the
creation of a VBE by a third authority is considered: chambers of commerce, as
organizations whose goal is to promote and facilitate business interests and
activity in the community, could be good candidates for exogenous VBE creators.
During VBE planning, there is a need to specify social requirements for the
VBE. In this paper, SNA metrics are proposed as a way for a VBE planner to
express social requirements for a VBE to be created. Additionally, a set of
social requirements for VO planners, VO brokers, and VBE members are proposed.Comment: 10 pages, 2 figure
Oscillatons revisited
In this paper, we study some interesting properties of a spherically
symmetric oscillating soliton star made of a real time-dependent scalar field
which is called an oscillaton. The known final configuration of an oscillaton
consists of a stationary stage in which the scalar field and the metric
coefficients oscillate in time if the scalar potential is quadratic. The
differential equations that arise in the simplest approximation, that of
coherent scalar oscillations, are presented for a quadratic scalar potential.
This allows us to take a closer look at the interesting properties of these
oscillating objects. The leading terms of the solutions considering a quartic
and a cosh scalar potentials are worked in the so called stationary limit
procedure. This procedure reveals the form in which oscillatons and boson stars
may be related and useful information about oscillatons is obtained from the
known results of boson stars. Oscillatons could compete with boson stars as
interesting astrophysical objects, since they would be predicted by scalar
field dark matter models.Comment: 10 pages REVTeX, 10 eps figures. Updated files to match version
published in Classical and Quantum Gravit
Beating of Friedel oscillations induced by spin-orbit interaction
By exploiting our recently derived exact formula for the Lindhard
polarization function in the presence of Bychkov-Rashba (BR) and Dresselhaus
(D) spin-orbit interaction (SOI), we show that the interplay of different SOI
mechanisms induces highly anisotropic modifications of the static dielectric
function. We find that under certain circumstances the polarization function
exhibits doubly-singular behavior, which leads to an intriguing novel
phenomenon, beating of Friedel oscillations. This effect is a general feature
of systems with BR+D SOI and should be observed in structures with a
sufficiently strong SOI.Comment: 3 figure
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