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Financing SMEs: a model for optimising the capital structure
This paper argues that the existing finance literature is inadequate with respect to its cov-erage of capital structure of small and medium sized enterprises (SMEs). In particular it is argued that the cost of equity (being both conceptually ill defined and empirically non quantifiable) is not applicable to the capital structure decisions for a large proportion of SMEs and the optimal capital structure depends only on the mix of short and long term debt. The paper then presents a model for optimising the debt mix and demonstrates its practical application using an Italian firm’s debt structure as a case study
Computational approaches to shed light on molecular mechanisms in biological processes
Computational approaches based on Molecular Dynamics simulations, Quantum Mechanical methods and 3D Quantitative Structure-Activity Relationships were employed by computational chemistry groups at the University of Milano-Bicocca to study biological processes at the molecular level. The paper reports the methodologies adopted and the results obtained on Aryl hydrocarbon Receptor and homologous PAS proteins mechanisms, the properties of prion protein peptides, the reaction pathway of hydrogenase and peroxidase enzymes and the defibrillogenic activity of tetracyclines. © Springer-Verlag 2007
Emergence of pulled fronts in fermionic microscopic particle models
We study the emergence and dynamics of pulled fronts described by the
Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) equation in the microscopic
reaction-diffusion process A + A A$ on the lattice when only a particle is
allowed per site. To this end we identify the parameter that controls the
strength of internal fluctuations in this model, namely, the number of
particles per correlated volume. When internal fluctuations are suppressed, we
explictly see the matching between the deterministic FKPP description and the
microscopic particle model.Comment: 4 pages, 4 figures. Accepted for publication in Phys. Rev. E as a
Rapid Communicatio
Evaluating GAIA performances on eclipsing binaries. I. Orbits and stellar parameters for V505 Per, V570 Per and OO Peg
The orbits and physical parameters of three detached, double-lined A-F
eclipsing binaries have been derived combining H_P, V_T, B_T photometry from
the Hipparcos/Tycho mission with 8500-8750 Ang ground-based spectroscopy,
mimicking the photometric+spectroscopic observations that should be obtained by
GAIA, the approved Cornerstone 6 mission by ESA. This study has two main
objectives, namely (a) to derive reasonable orbits for a number of new
eclipsing binaries and (b) to evaluate the expected performances by GAIA on
eclipsing binaries and the accuracy achievable on the determination of
fundamental stellar parameters like masses and radii. It is shown that a 1%
precision in the basic stellar parameters can be achieved by GAIA on well
observed detached eclipsing binaries provided that the spectroscopic
observations are performed at high enough resolution. Other types of eclipsing
binaries (including semi-detached and contact types) and different spectral
types will be investigated in following papers along this series.Comment: A&A, 11 pages, 5 figures, 5 table
Fluctuating "Pulled" Fronts: the Origin and the Effects of a Finite Particle Cutoff
Recently it has been shown that when an equation that allows so-called pulled
fronts in the mean-field limit is modelled with a stochastic model with a
finite number of particles per correlation volume, the convergence to the
speed for is extremely slow -- going only as .
In this paper, we study the front propagation in a simple stochastic lattice
model. A detailed analysis of the microscopic picture of the front dynamics
shows that for the description of the far tip of the front, one has to abandon
the idea of a uniformly translating front solution. The lattice and finite
particle effects lead to a ``stop-and-go'' type dynamics at the far tip of the
front, while the average front behind it ``crosses over'' to a uniformly
translating solution. In this formulation, the effect of stochasticity on the
asymptotic front speed is coded in the probability distribution of the times
required for the advancement of the ``foremost bin''. We derive expressions of
these probability distributions by matching the solution of the far tip with
the uniformly translating solution behind. This matching includes various
correlation effects in a mean-field type approximation. Our results for the
probability distributions compare well to the results of stochastic numerical
simulations. This approach also allows us to deal with much smaller values of
than it is required to have the asymptotics to be valid.Comment: 26 pages, 11 figures, to appear in Phys. rev.
Symbiotic stars on Asiago archive plates. I
The rich plate archive of the Asiago observatory has been searched for plates
containing the symbiotic stars AS 323, Ap 3-1, CM Aql, V1413 Aql (=AS 338),
V443 Her, V627 Cas (=AS 501) and V919 Sgr. The program objects have been found
on 602 plates, where their brightness has been estimated against the UBVRI
photometric sequences calibrated by Henden and Munari (2000, A&AS 143, 343). AS
323 is probably eclipsing, with a preliminary P=197.6 day period. If confirmed,
it would be the shortest orbital period known among symbiotic stars. CM Aql
does not seem to undergo a series of outbursts, its lightcurve being instead
modulated by a large amplitude sinusoidal variation with a P~1058 day period.
V627 Cas presents a secular trend in agreement with the possible post-AGB
nature of its cool component.Comment: A&A in pres
Copper benchmark experiment for the testing of JEFF-3.2 nuclear data for fusion applications
A neutronics benchmark experiment on a pure Copper block (dimensions 60 × 70 × 70 cm3) aimed at testing and validating the recent nuclear data libraries for fusion applications was performed in the frame of the European Fusion Program at the 14 MeV ENEA Frascati Neutron Generator (FNG). Reaction rates, neutron flux spectra and doses were measured using different experimental techniques (e.g. activation foils techniques, NE213 scintillator and thermoluminescent detectors). This paper first summarizes the analyses of the experiment carried-out using the MCNP5 Monte Carlo code and the European JEFF-3.2 library. Large discrepancies between calculation (C) and experiment (E) were found for the reaction rates both in the high and low neutron energy range. The analysis was complemented by sensitivity/uncertainty analyses (S/U) using the deterministic and Monte Carlo SUSD3D and MCSEN codes, respectively. The S/U analyses enabled to identify the cross sections and energy ranges which are mostly affecting the calculated responses. The largest discrepancy among the C/E values was observed for the thermal (capture) reactions indicating severe deficiencies in the 63,65Cu capture and elastic cross sections at lower rather than at high energy. Deterministic and MC codes produced similar results. The 14 MeV copper experiment and its analysis thus calls for a revision of the JEFF-3.2 copper cross section and covariance data evaluation. A new analysis of the experiment was performed with the MCNP5 code using the revised JEFF-3.3-T2 library released by NEA and a new, not yet distributed, revised JEFF-3.2 Cu evaluation produced by KIT. A noticeable improvement of the C/E results was obtained with both new libraries
The distance to the Pleiades from orbital solution of the double-lined eclipsing binary HD 23642
Combining precise B,V photoelectric photometry and radial velocities, we have
been able to derive a firm orbital solution and accurate physical parameters
for the newly discovered eclipsing binary HD 23642 in the Pleiades open
cluster. The resulting distance to the binary, and therefore to the cluster, is
132 +/- 2 pc. This closely confirms the distance modulus obtained by classical
main sequence fitting methods (m-M = 5.60 or 132 pc), moving cluster techniques
and the astrometric orbit of Atlas. This is the first time the distance to a
member of the Pleiades is derived by orbital solution of a double-lined
eclipsing binary, and it is intended to contribute to the ongoing discussion
about the discordant Hipparcos distance to the cluster.Comment: accepted in press in A&A as Letter to the Edito
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