36,527 research outputs found
SURVIVAL OF THE SMALL FIRM AND THE ENTREPRENEUR UNDER DEMAND AND EFFICIENCY UNCERTAINTY
The objective of this paper is to offer an answer to the question : why do some entrepreneurs wish to own another firm in the future after having closed an unsuccessful one? We first show this question is relevant because making use of a sample of entrepreneurs in the UK who have experienced a business closure, we show that 45% of them have the desire to own another firm in the future, despite having an unsuccessful experience in small firm ownership. To tackle our question we develop a model where the profits of the small firm depend on two firm-specific parameters : the effciency parameter, which represents the skills of the entrepreneur to manage and cope efficiently with the everyday tasks of the small firm, and the demand parameter, which denotes the success of the firm’s product to attract demand or capture a market niche. It is found that our model answers our initial question by revealing the existence of a mechanism of entrepreneurial self-selection. Under such mechanism, skilful entrepreneurs are the only ones who wish to own another firm in the future, regardless of the degree of success in their previous venture, whereas unskilful entrepreneurs prefer to go to wage work. We show this mechanism accounts not only for the empirical evidence relevant to our initial question, but also for the rest of cases of entrepreneurs’ attitudes after experiencing a business closureSmall Firm ; Entrepreneur ; Survival ; Entrepreneurial Skills
Models for gamma-ray production in low-mass microquasars
Unlike high-mass gamma-ray binaries, low-mass microquasars lack external
sources of radiation and matter that could produce high-energy emission through
interactions with relativistic particles. In this work we consider the
synchrotron emission of protons and leptons that populate the jet of a low-mass
microquasar. In our model photohadronic and inverse Compton (IC) interactions
with synchrotron photons produced by both protons and leptons result in a
high-energy tail of the spectrum. We also estimate the contribution from
secondary pairs injected through photopair production. The high-energy emission
is dominated by radiation of hadronic origin, so we can call these objects
proton microquasars.Comment: 4 pages, 2 figures, accepted for publication in the International
Journal of Modern Physics D, proceedings of HEPRO meeting, held in Dublin, in
September 200
Microquasar models for 3EG J1828+0142 and 3EG J1735-1500
Microquasars are promising candidates to emit high-energy gamma-rays.
Moreover, statistical studies show that variable EGRET sources at low galactic
latitudes could be associated with the inner spiral arms. The variable nature
and the location in the Galaxy of the high-mass microquasars, concentrated in
the galactic plane and within 55 degrees from the galactic center, give to
these objects the status of likely counterparts of the variable low-latitude
EGRET sources. We consider in this work the two most variable EGRET sources at
low-latitudes: 3EG J1828+0142 and 3EG J1735-1500, proposing a microquasar model
to explain the EGRET data in consistency with the observations at lower
energies (from radio frequencies to soft gamma-rays) within the EGRET error
box.Comment: (1)Universitat de Barcelona, (2)Instituto Argentino de
Radioastronomia (3) Facultad de Ciencias Astronomicas y Geofisicas
(4)Lawrence Livermore National Laboratory 6 pages, 2 figures. Presented as a
poster at the V Microquasar Workshop, Beijing, June 2004. Accepted for
publication in the Chinese Journal of Astronomy & Astrophysic
Probing magnetic order in ultracold lattice gases
A forthcoming challenge in ultracold lattice gases is the simulation of
quantum magnetism. That involves both the preparation of the lattice atomic gas
in the desired spin state and the probing of the state. Here we demonstrate how
a probing scheme based on atom-light interfaces gives access to the order
parameters of nontrivial quantum magnetic phases, allowing us to characterize
univocally strongly correlated magnetic systems produced in ultracold gases.
This method, which is also nondemolishing, yields spatially resolved spin
correlations and can be applied to bosons or fermions. As a proof of principle,
we apply this method to detect the complete phase diagram displayed by a chain
of (rotationally invariant) spin-1 bosons.Comment: published versio
Interpretation of experimental results on Kondo systems with crystal field
We present a simple approach to calculate the thermodynamic properties of
single Kondo impurities including orbital degeneracy and crystal field effects
(CFE) by extending a previous proposal by K. D. Schotte and U. Schotte [Physics
Lett. A 55, 38 (1975)]. Comparison with exact solutions for the specific heat
of a quartet ground state split into two doublets shows deviations below
in absence of CFE and a quantitative agreement for moderate or large CFE. As an
application, we fit the measured specific heat of the compounds CeCuGe,
CePdSi, CePdAl, CePt, YbPdSn and YbCoZn. The
agreement between theory and experiment is very good or excellent depending on
the compound, except at very low temperatures due to the presence of magnetic
correlations (not accounted in the model)
- …