3,876 research outputs found
Business Incubators: Creation of a Fit in Armenia
In this paper, we evaluate the extent to which business incubation services meet tenant’s needs. Additionally, we pose the question of whether the current business incubators actually cover the needs of a particular industry. Our empirical setting is a developing country in the Caucasian Region (Armenia) and we chose to research solely the IT industry. We employed a two stage procedure: first, we conducted interviews with pivotal people familiar with business incubation in Armenia; second, an electronic questionnaire survey was sent to the entire Armenian IT population. The results suggest a moderate need of IT companies for the typical business incubation services. Further, we show that incubated companies are generally satisfied with the services they enjoy albeit this satisfaction level decreases as the needs increase. Non-incubated companies, on the other hand, perceive incubation services to be valuable for their development and this value increases when their needs increase. Our study implies that a more extensive service provision is necessary to fully cover the needs of the Armenian IT industry for business incubation services
New perturbative solutions of the Kerr-Newman dilatonic black hole field equations
This work describes new perturbative solutions to the classical,
four-dimensional Kerr--Newman dilaton black hole field equations. Our solutions
do not require the black hole to be slowly rotating. The unperturbed solution
is taken to be the ordinary Kerr solution, and the perturbation parameter is
effectively the square of the charge-to-mass ratio of the
Kerr--Newman black hole. We have uncovered a new, exact conjugation (mirror)
symmetry for the theory, which maps the small coupling sector to the strong
coupling sector (). We also calculate the gyromagnetic ratio of
the black hole.Comment: Revtex, 27 page
Theoretical survey of tidal-charged black holes at the LHC
We analyse a family of brane-world black holes which solve the effective
four-dimensional Einstein equations for a wide range of parameters related to
the unknown bulk/brane physics. We first constrain the parameters using known
experimental bounds and, for the allowed cases, perform a numerical analysis of
their time evolution, which includes accretion through the Earth. The study is
aimed at predicting the typical behavior one can expect if such black holes
were produced at the LHC. Most notably, we find that, under no circumstances,
would the black holes reach the (hazardous) regime of Bondi accretion.
Nonetheless, the possibility remains that black holes live long enough to
escape from the accelerator (and even from the Earth's gravitational field) and
result in missing energy from the detectors.Comment: RevTeX4, 12 pages, 4 figures, 5 tables, minor changes to match the
accepted version in JHE
Seismic topographic scattering in the context of GW detector site selection
In this paper, we present a calculation of seismic scattering from irregular
surface topography in the Born approximation. Based on US-wide topographic
data, we investigate topographic scattering at specific sites to demonstrate
its impact on Newtonian-noise estimation and subtraction for future
gravitational-wave detectors. We find that topographic scattering at a
comparatively flat site in Oregon would not pose any problems, whereas
scattering at a second site in Montana leads to significant broadening of wave
amplitudes in wavenumber space that would make Newtonian-noise subtraction very
challenging. Therefore, it is shown that topographic scattering should be
included as criterion in the site-selection process of future low-frequency
gravitational-wave detectors.Comment: 16 pages, 7 figure
Perturbations in the Kerr-Newman Dilatonic Black Hole Background: Maxwell Waves, the Dilaton Background and Gravitational Lensing
In this paper we continue the analysis of our previous papers and study the
affect of the existence of a non-trivial dilaton background on the propagation
of electromagnetic waves in the Kerr-Newman dilatonic black hole space-time.
For this purpose we again employ the double expansion in both the background
electric charge and the wave parameters of the relevant quantities in the
Newman-Penrose formalism and then identify the first order at which the dilaton
background enters the Maxwell equations. We then assume that gravitational and
dilatonic waves are negligible (at that order in the charge parameter) with
respect to electromagnetic waves and argue that this condition is consistent
with the solutions already found in the previous paper. Explicit expressions
are given for the asymptotic behavior of scattered waves, and a simple physical
model is proposed in order to test the effects. An expression for the relative
intensity is obtained for Reissner-Nordstrom dilaton black holes using
geometrical optics. A comparison with the approximation of geometrical optics
for Kerr-Newman dilaton black holes shows that at the order to which the
calculations are carried out gravitational lensing of optical images cannot
probe the dilaton background.Comment: 9 pages, 1 figur
Electromagnetic waves around dilatonic stars and naked singularities
We study the propagation of classical electromagnetic waves on the simplest
four-dimensional spherically symmetric metric with a dilaton background field.
Solutions to the relevant equations are obtained perturbatively in a parameter
which measures the strength of the dilaton field (hence parameterizes the
departure from Schwarzschild geometry). The loss of energy from outgoing modes
is estimated as a back-scattering process against the dilaton background, which
would affect the luminosity of stars with a dilaton field. The radiation
emitted by a freely falling point-like source on such a background is also
studied by analytical and numerical methods.Comment: 9 pages, 1 figur
Ghost Busting: PT-Symmetric Interpretation of the Lee Model
The Lee model was introduced in the 1950s as an elementary quantum field
theory in which mass, wave function, and charge renormalization could be
carried out exactly. In early studies of this model it was found that there is
a critical value of g^2, the square of the renormalized coupling constant,
above which g_0^2, the square of the unrenormalized coupling constant, is
negative. Thus, for g^2 larger than this critical value, the Hamiltonian of the
Lee model becomes non-Hermitian. It was also discovered that in this
non-Hermitian regime a new state appears whose norm is negative. This state is
called a ghost state. It has always been assumed that in this ghost regime the
Lee model is an unacceptable quantum theory because unitarity appears to be
violated. However, in this regime while the Hamiltonian is not Hermitian, it
does possess PT symmetry. It has recently been discovered that a non-Hermitian
Hamiltonian having PT symmetry may define a quantum theory that is unitary. The
proof of unitarity requires the construction of a new time-independent operator
called C. In terms of C one can define a new inner product with respect to
which the norms of the states in the Hilbert space are positive. Furthermore,
it has been shown that time evolution in such a theory is unitary. In this
paper the C operator for the Lee model in the ghost regime is constructed
exactly in the V/N-theta sector. It is then shown that the ghost state has a
positive norm and that the Lee model is an acceptable unitary quantum field
theory for all values of g^2.Comment: 20 pages, 9 figure
Matrix Theory Description of Schwarzschild Black Holes in the Regime N >> S
We study the description of Schwarzschild black holes, of entropy S, within
matrix theory in the regime . We obtain the most general matrix
theory equation of state by requiring that black holes admit a description
within this theory. It has a recognisable form in various cases. In some cases
a D dimensional black hole can plausibly be thought of as a
dimensional black hole, described by another auxiliary matrix theory, but in
its regime. We find what appears to be a matrix theory
generalisation to higher dynamical branes of the normalisation of dynamical
string tension, seen in other contexts. We discuss a further possible
generalisation of the matrix theory equation of state. In a special case, it is
governed by dynamical degrees of freedom.Comment: 22 pages. Latex fil
Rotational Correlation Functions of Single Molecules
Single molecule rotational correlation functions are analyzed for several
reorientation geometries. Even for the simplest model of isotropic rotational
diffusion our findings predict non-exponential correlation functions to be
observed by polarization sensitive single molecule fluorescence microscopy.
This may have a deep impact on interpreting the results of molecular
reorientation measurements in heterogeneous environments.Comment: 5 pages, 4 figure
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