Understanding the Variations in Gibrat's Law with a Markov-Perfect Dynamic Industry Model

Gibrat's Law of proportionate effect, as applied to firms, states that the growth rate of a firm is independent of its size. Empirical work on firm dynamics finds crucial deviations from Gibrat's Law such as smaller firms growing faster than larger firms (Evans, 1987, and Hall, 1987), a negative relationship between the variance of growth rates and size (Dunne and Hughes, 1994), and first-order positive autocorrelation in the growth rates (Kumar, 1995). Moreover, the degree of deviation from Gibrat's Law varies across industries. This paper contributes to our understanding of the forces that make Gibrat's Law a close, but imperfect approximation of firm size distributions and seeks to determine potential sources of cross-industry variation. Here, we employ an extension of the Ericson-Pakes (1995) theoretical framework that allows for firm growth developed by Laincz (2004a). By varying key parameters, the simulations demonstrate potential sources for the various, and sometimes conflicting, results on Gibrat's Law uncovered in the empirical literatureGibrat's Law, Firm Size Distribution, Entry, Exit

A Theoretical Foundation for Understanding Firm Size Distributions and Gibrat's Law

This paper presents a dynamic model of the firm size distribution. Empirical studies of the firm size distribution often compare the moments to a log-normal distribution as implied by Gibrat's Law and note important deviations. Thus, the first, and basic questions we ask are how well does the dynamic industry model reproduce Gibrat's Law and how well does it match the deviations uncovered in the literature. We show that the model reproduces these results when testing the simulated output using the techniques of the empirical literature. We then use the model to study how structural parameters affect the firm size distribution. We find that, among other things, fixed and sunk costs increase both the mean and variance of the firm size distribution while generally decreasing the skewness and kurtosis. The rate of growth in an industry also raises the mean and variance, but has non-monotonic effects on the higher moments.Firm size distribution; Gibrat's Law; R&D.

Neuropilin 1 Regulation of Vascular Permeability Signaling.

The vascular endothelium acts as a selective barrier to regulate macromolecule exchange between the blood and tissues. However, the integrity of the endothelium barrier is compromised in an array of pathological settings, including ischemic disease and cancer, which are the leading causes of death worldwide. The resulting vascular hyperpermeability to plasma molecules as well as leukocytes then leads to tissue damaging edema formation and inflammation. The vascular endothelial growth factor A (VEGFA) is a potent permeability factor, and therefore a desirable target for impeding vascular hyperpermeability. However, VEGFA also promotes angiogenesis, the growth of new blood vessels, which is required for reperfusion of ischemic tissues. Moreover, edema increases interstitial pressure in poorly perfused tumors, thereby affecting the delivery of therapeutics, which could be counteracted by stimulating the growth of new functional blood vessels. Thus, targets must be identified to accurately modulate the barrier function of blood vessels without affecting angiogenesis, as well as to develop more effective pro- or anti-angiogenic therapies. Recent studies have shown that the VEGFA co-receptor neuropilin 1 (NRP1) could be playing a fundamental role in steering VEGFA-induced responses of vascular endothelial cells towards angiogenesis or vascular permeability. Moreover, NRP1 is involved in mediating permeability signals induced by ligands other than VEGFA. This review therefore focuses on current knowledge on the role of NRP1 in the regulation of vascular permeability signaling in the endothelium to provide an up-to-date landscape of the current knowledge in this field

Computational Intelligence in Serious Games: a case study to identify patterns in a game for children with learning disabilities

This work explores the application of computational intelligence techniques in a serious game (SG) for children with learning disabilities. Specifically, we apply Data Mining (DM) techniques such as Decision Tree and Apriori algorithms aiming to identify the existence of patterns that would allow a better understanding on the profiles of children involved in the game. The data analyzed are related to the interaction of twenty children with the considered SG, which consists of a three dimensional virtual zoo, developed with features that appeal to the preferences of children about nine years old in order to assist and motivate their learning. The results obtained in the conducted experiments revealed patterns in the profiles of the game's players under analysis, allowing to identify some characteristics that can help the psychopedagogical team. These findings can also enable the improvement of the game making it adaptable to different player profiles.info:eu-repo/semantics/publishedVersio

Artificial Intelligence identifying patterns in the social interaction of senior individuals through online activities at Virtual Senior University in Pandemic

Objectives: Data Mining techniques applied to observe patterns in the social interaction of senior individuals during their participation in the online activities that were proposed by the Virtual Senior University during the pandemic. Methodology: Zoom and Facebook platforms were used to streamline conversations, videos with student performances and homework during the COVID-19 pandemic. The experiments conducted enabled the application of the Artificial Intelligence technique called Data Mining to perform statistical analyses and identify profiles based on the social interaction of the individuals who participated in the online activities. Participants answered about Gender, Age (years), Marital Status, Time attending Senior University and Participation in online activities. They also answered about their participation in these activities, informing if it increased, decreased, remained unchanged or if they did not participate. To carry out the analyses of the collected data, age groups were organized, being 50 to 64 years, 65 to 74 years and 75 or more years. Results and Discussion: It was observed that the majority of seniors who had been attending the Virtual Senior University since before 2020, aged between 50 and 64 years, reported that their participation in online activities had increased. According to the analysis that was carried out, it was possible to correctly classify 76.087% of the data. The accuracy described through the Kappa statistic coefficient showed reliability in the data showing a score of 0.6383 and corresponding to a substantial agreement (range between 0.61 and 0.80). Conclusions: The Data Mining technique applied in this study suggests that there was statistical significance for the analyses carried out based on the social interaction of senior individuals, in the age group between 50 and 64 years old, who participated in the online activities proposed by the Virtual Senior University during the pandemic. Different activities are suggested for the other age groups.info:eu-repo/semantics/publishedVersio

Acceptance of an agile methodology in the public sector

Software development methodologies have been growing up and suffering a maturation during the past years. The older methods, called traditional methods, are gradually being substitute by the new agile practices. Despite that, in the public sector, that evolution is not as clear as in the private sector. The lack of information regarding the usage of these new methods in the public sector take us to the following question: In what conditions, agile methods, are the best solution to software development in the public sector? These types of organizations have a culture and a modus operandi very different from the private sector, that can make the implementation of these methodologies a challenge. The goal here is to present the process of implementation of a specific agile methodology based in Scrum, in a particular Portuguese public company and test its acceptance.info:eu-repo/semantics/publishedVersio

An open and parallel multiresolution framework using block-based adaptive grids

A numerical approach for solving evolutionary partial differential equations in two and three space dimensions on block-based adaptive grids is presented. The numerical discretization is based on high-order, central finite-differences and explicit time integration. Grid refinement and coarsening are triggered by multiresolution analysis, i.e. thresholding of wavelet coefficients, which allow controlling the precision of the adaptive approximation of the solution with respect to uniform grid computations. The implementation of the scheme is fully parallel using MPI with a hybrid data structure. Load balancing relies on space filling curves techniques. Validation tests for 2D advection equations allow to assess the precision and performance of the developed code. Computations of the compressible Navier-Stokes equations for a temporally developing 2D mixing layer illustrate the properties of the code for nonlinear multi-scale problems. The code is open source

Transition of athletes in sport career: from theory to evaluation

Este trabalho analisa a transição dos atletas no desporto, propondo um modelo compreensivo da transição desportiva e um instrumento de avaliação para analisar as transições desportivas dos atletas ao longo da carreira desportiva. Assim, do ponto de vista conceptual descreve-se o Modelo Interativo de Adaptação Humana à Transição Desportiva, que entende este fenómeno como um processo constituído pelos seguintes fatores: (a) circunstâncias da transição desportiva, (b) processos de avaliação cognitiva, (c) respostas ocorridas durante a situação de transição, e (d) resultado final da situação de transição. De seguida, é proposto um guião de entrevista para avaliar a transição desportiva, avaliando seis dimensões: (a) situação de transição, (b) recursos externos disponíveis, (c) mudanças enfrentadas, (d) processos de avaliação cognitiva, (e) respostas psicológicas, fisiológicas e comportamentais, e (f) resultado final da adaptação desportiva. A conjugação de modelos teóricos e instrumentos de avaliação acerca da transição desportiva podem ajudar a compreender este fenómeno.This work analyzes the transition of athletes in sports, proposing a comprehensive model about career transition and an instrument to evaluate the transitions of athletes throughout their careers. First, it is described the Interactive Model of Human Adaptation to Career Transition, proposing that transition is a process constituted by the following factors: (a) circumstances of the career transition, (b) cognitive appraisal, (c) responses occurred during the career transition, and (d) final result of the career transition. Second, it is proposed an interview guide that evaluates six dimensions: (a) circumstances of the career transition, (b) available external resources, (c) demands faced during the career transition, (d) processes of cognitive appraisal, (e) psychological, physiological and behavioral responses, and (f) final result of career transition. The combination of theoretical models and evaluation instruments about the career transition may help to understand this phenomenon.(undefined

SAMplus: adaptive optics at optical wavelengths for SOAR

Adaptive Optics (AO) is an innovative technique that substantially improves the optical performance of ground-based telescopes. The SOAR Adaptive Module (SAM) is a laser-assisted AO instrument, designed to compensate ground-layer atmospheric turbulence in near-IR and visible wavelengths over a large Field of View. Here we detail our proposal to upgrade SAM, dubbed SAMplus, that is focused on enhancing its performance in visible wavelengths and increasing the instrument reliability. As an illustration, for a seeing of 0.62 arcsec at 500 nm and a typical turbulence profile, current SAM improves the PSF FWHM to 0.40 arcsec, and with the upgrade we expect to deliver images with a FWHM of $\approx0.34$ arcsec -- up to 0.23 arcsec FWHM PSF under good seeing conditions. Such capabilities will be fully integrated with the latest SAM instruments, putting SOAR in an unique position as observatory facility.Comment: To appear in Proc. SPIE 10703 (Ground-based and Airborne Instrumentation for Astronomy VII; SPIEastro18