13,575 research outputs found
Determinants of high-growth firms
High-growth firms have been shown to be a key factor for economic growth and structural change. This paper analyses the determinants of the number of highgrowth firms in a country for 17 OECD countries between 1999 and 2005, using the Amadeus data set, the GEM data set, and others. The first contribution of this paper is that it is - as far as we know - the first empirical analysis of highgrowth firms at the country level on the basis of actual measured growth. Second, we find indicative empirical evidence for three driving forces of high growth, viz. entrepreneurship, institutional settings, and opportunities for growth, all in accordance with theory and empirical findings in related fields of research. Third, the paper gives a tentative explanation of the differences in the average percentage of high-growth firms between countries. Finally, the paper gives some clues for policy makers how to promote high-growth firms. �
Individual prediction of automobile bodily injury claims liabilities
Most motor bodily injury (BI) claims are settled by negotiation, with fewer than 5% of cases going to court. A well-defined negotiation strategy is thus very useful for insurance companies. In this paper we assume that the monetary compensation awarded in court is the upper amount to be offered by the insurer in the negotiation process. Using a real database, a log-linear model is implemented to estimate the maximal offer. Non-spherical disturbances are detected. Correlation occurs when various claims are settled in the same judicial verdict. Groupwise heteroscedasticity is due to the influence of the forensic valuation on the final compensation amount.multivariate statistics, negotiation process, generalized confidence intervals
Inhomogenous loop quantum cosmology with matter
The linearly polarized Gowdy model with a massless scalar field with
the same symmetries as the metric is quantized by applying a hybrid approach.
The homogeneous geometry degrees of freedom are loop quantized, fact which
leads to the resolution of the cosmological singularity, while a Fock
quantization is employed for both matter and gravitational inhomogeneities.
Owing to the inclusion of the massless scalar field this system allows us to
modelize flat Friedmann-Robertson-Walker cosmologies filled with
inhomogeneities propagating in one direction. It provides a perfect scenario to
study the quantum back-reaction between the inhomogeneities and the polymeric
homogeneous and isotropic background.Comment: 4 pages, Contribution to the proceedings of the Loops 11-Madrid
conferenc
Perceived parenting and social support: can they predict academic achievement in Argentinean college students?
The aim of this study was to test the ability to predict academic achievement through the perception of parenting and social support in a sample of 354 Argentinean college students. Their mean age was 23.50 years (standard deviation =2.62 years) and most of them (83.3%) were females. As a prerequisite for admission to college, students are required to pass a series of mandatory core classes and are expected to complete them in two semesters. Delay in completing the curriculum is considered low academic achievement. Parenting was assessed taking into account the mother and the father and considering two dimensions: responsiveness and demandingness. Perceived social support was analyzed considering four sources: parents, teachers, classmates, and best friend or boyfriend/girlfriend. Path analysis showed that, as hypothesized, responsiveness had a positive indirect effect on the perception of social support and enhanced achievement. Demandingness had a different effect in the case of the mother as compared to the father. In the mother model, demandingness had a positive direct effect on achievement. In the case of the father, however, the effect of demandingness had a negative and indirect impact on the perception of social support. Teachers were the only source of perceived social support that significantly predicted achievement. The pathway that belongs to teachers as a source of support was positive and direct. Implications for possible interventions are discussed.Fil: de la Iglesia, Guadalupe. Universidad de Buenos Aires. Facultad de PsicologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Freiberg Hoffmann, AgustÃn. Universidad de Buenos Aires. Facultad de PsicologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Fernandez Liporace, Maria Mercedes. Universidad de Buenos Aires. Facultad de PsicologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
Inclusion of matter in inhomogeneous loop quantum cosmology
We study the hybrid quantization of the linearly polarized Gowdy model
with a massless scalar field with the same symmetries as the metric. For
simplicity, we quantize its restriction to the model with local rotational
symmetry. Using this hybrid approach, the homogeneous degrees of freedom of the
geometry are quantized \`a la loop, leading to the resolution of the
cosmological singularity. A Fock quantization is employed both for the matter
and the gravitational inhomogeneities. Owing to the inclusion of the massless
scalar field this system allows us to modelize flat Friedmann-Robertson-Walker
cosmologies filled with inhomogeneities propagating in one direction, providing
a perfect scenario to study the quantum back-reaction of the inhomogeneities on
the polymeric homogeneous and isotropic background.Comment: 4 pages. Contribution to the Proceedings of Spanish Relativity
Meeting ERE2011, Madrid 201
Approximation methods in Loop Quantum Cosmology: From Gowdy cosmologies to inhomogeneous models in Friedmann-Robertson-Walker geometries
We develop approximation methods in the hybrid quantization of the Gowdy
model with linear polarization and a massless scalar field, for the case of
three-torus spatial topology. The loop quantization of the homogeneous
gravitational sector of the Gowdy model (according to the improved dynamics
prescription) and the presence of inhomogeneities lead to a very complicated
Hamiltonian constraint. Therefore, the extraction of physical results calls for
the introduction of well justified approximations. We first show how to
approximate the homogeneous part of the Hamiltonian constraint, corresponding
to Bianchi I geometries, as if it described a Friedmann-Robertson-Walker (FRW)
model corrected with anisotropies. This approximation is valid in the
high-energy sector of the FRW geometry (concerning its contribution to the
constraint) and for anisotropy profiles that are sufficiently smooth. In
addition, for certain families of states associated to regimes of physical
interest, with negligible effects of the anisotropies and small
inhomogeneities, one can approximate the Hamiltonian constraint of the
inhomogeneous system by that of an FRW geometry with a relatively simple matter
content, and then obtain its solutions.Comment: 20 pages, 3 figures. Minor changes, matches published versio
Los medios de comunicación ante la violencia machista: ¿mensajeros del miedo o altavoces de la esperanza?
Grupo de Investigación en Estructura, Historia y Contenidos de la Comunicación. GREHCCO HUM618Laboratorio de Estudios en Comunicación (LADECOM
Germination responses to light of four Neotropical forest tree species along an elevational gradient in the southern Central Andes
Seed germination is a key part of plants' life cycle and is mostly affected by the genetic background, the environmental conditions experienced by the mother plant and the seedbed conditions. The germination response to light is essential to optimize germination and seedling establishment in space and time. In addition, the germination response to light is a trait often related to the response of the seeds to their position in the soil (uncovered/buried). Here, we studied the germination response to light of four key tree species of the Yungas forest (Anadenanthera colubrina, Enterolobium contortisiliquum, Jacaranda mimosifolia and Handroanthus impetiginosus) sampled along an elevational and environmental gradient with contrasting vegetation cover and disturbance. Relative light germination (RLG) and mean germination time (MGT) were determined. Final germination was tested under cycles of light (8 h) and darkness (16 h) versus complete darkness (24 h) and elevation, and MGT was tested as a function of elevation of the provenance. The RLG increased from smaller to larger-seeded species. The MGT of three of the studied species was affected by the elevation of the provenance. Complete darkness negatively affected final germination, while two species exhibited a significant interaction between the provenance and light. The variable germination responses to light along the elevational gradient highlights the influence of the environment on germination as a key factor that should be considered for forest management, conservation and restoration projects
Compliance with Social Norms as an Evolutionary Stable Equilibrium
Producción CientÃficaThis paper studies a two-population evolutionary game in a new setting
in between a symmetric and an asymmetric evolutionary model. It distinguishes two
types of agents: Sanchos, whose payoffs are defined by a prisoner’s dilemma game,
and Quixotes, whose payoffs are defined by a snowdrift game. Considering an imita-
tive revision protocol, a revising agent is paired with someone from his own popula-
tion or the other population. When matched, they observe payoffs, but not identities.
Thus, agents in one population interact and imitate agents from their own population
and from the other population. In this setting we prove that a unique mixed-strategy
asymptotically stable fixed point of the evolutionary dynamics exists. Taking as an
example the compliance with social norms, and depending on the parameters, two
type of equilibrium are possible, one with full compliance among Quixotes and par-
tial compliance among Sanchos, or another with partial compliance among Quixotes
and defection among Sanchos. In the former type, Sanchos comply above their Nash
equilibrium (as they imitate compliant Quixotes). In the latter type, Quixotes comply
below their Nash equilibrium (as they imitate defecting Sanchos).This study was funded by the Spanish Government (projects ECO2014- 52343-P and ECO2017-82227-P), as well as financial aid from Junta de Castilla y León (projects VA024P17 and VA105G18), co-financed by FEDER funds
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