O valor terminal ou de continuidade, na avaliação de empresas

É um facto que a incerteza sobre o futuro das sociedades tem de ser modelada e incorporada na sua avaliação, fora do período explícito de análise, ou seja: nos valores de continuidade (VC), valor residual (VR) ou valor terminal (VT), considerados nos modelos de avaliação. Existem inúmeros fatores que influenciam o valor de continuidade das empresas e que não são, atualmente, considerados nos modelos de avaliação de empresas, destacando-se, entre os mais relevantes, a ausência de quaisquer referências à esperança média de vida das empresas. De facto, ao ignorarmos esses fatores, podemos incorrer em erros irreparáveis, conduzindo as avaliações a valores de goodwill ou badwill, muito longe do real valor substancial dos ativos, que lhes é intrínseco. Como consequência, os referidos resultados apresentar-se-ão vincadamente diferentes dos valores de mercado. Assim, porque não considerar modelos alternativos (incorporando nos mesmos a esperança de vida das empresas) e a influência de outros fatores, de forma a obter um ajustamento mais eficiente, no que respeita à forma de cálculo do valor da empresa? Este trabalho pretende fornecer um contributo neste domínio, tendo como primeiro objetivo (e para além da revisão da literatura existente sobre a matéria) a construção de uma tábua de mortalidade para as empresas portuguesas, que possa ser utilizada para eliminar ou, pelo menos, reduzir um dos principais problemas causadores de distorção dos atuais modelos de avaliação de empresas: a premissa de existência (ilimitada no tempo) de uma empresa. Com esse propósito, através da metodologia associada à construção de tábuas de mortalidade para os seres humanos, construímos uma tabela com a esperança média de vida associada às empresas portuguesas. Assim, usando uma base de dados (com cerca de 182.000 registos sobre falências, dissoluções e cessão de atividade em Portugal, desde 1900 até 2009), concluímos que, nos primeiros 5 anos, “morrem” 31% das empresas e que a esperança média de vida (à nascença) é de 12 anos. Estes resultados evidenciam a fragilidade dos modelos de avaliação de empresas, em que se estima o VT com uma perpetuidade. Após ficar patente que as empresas não têm uma esperança de vida infinita, preocupar-nos-emos em identificar quais os fatores responsáveis pela existência da empresa (no longo prazo), fatores esses que possam, porventura, justificar uma vida mais longa das sociedades. VI Nesse sentido, o segundo objetivo passou por identificar quais os fatores determinantes do valor terminal da empresa. Assim [utilizando uma amostra de 714 empresas cotadas, pertencentes a 15 países europeus e para um período compreendido entre 1992 e 2011, usando a metodologia GMM (Generalized method of moments), aplicada a dados em painel dinâmico], os resultados evidenciam que o valor de continuidade não pode ser considerado como o valor atual de uma perpetuidade constante (ou com crescimento) de um determinado atributo da empresa mas, sim, em função de um conjunto de atributos, como os free cash flows, os resultados líquidos, a esperança média de vida da empresa, o investimento em I&D, as capacidades e qualidade da gestão, a liquidez dos títulos e a estrutura de financiamento. Como terceiro objetivo (e mantendo a particular atenção na estimação do VT da empresa), procurou-se cruzar os resultados obtidos no estudo anterior com as perceções dos analistas Europeus e Estadunidenses acerca dos atributos da empresa que, na opinião destes, mais contribuem para o seu valor. Para o feito, recorreu-se a um inquérito, com respostas fechadas. Da análise das 123 respostas válidas, obtidas usando a análise fatorial, concluiuse serem determinantes do valor de uma empresa ou negócio os seguintes fatores: a esperança média de vida da empresa, a sua liquidez e desempenho operacional, a inovação e capacidade de afetação de recursos a I&D, as capacidades de gestão e a estrutura de capital, confirmando-se as conclusões até então obtidas. Por fim, fez-se um esforço no sentido de fornecer ao leitor uma nova aproximação teórica ao modelo Discounted CashFlow (DCF), tendo em conta as variáveis entretanto identificadas no nosso estudo. Estes resultados contribuem, a nosso ver, para que se possa caminhar no sentido da construção de um modelo de avaliação de empresas e negócios ainda mais apurado, em que os resultados obtidos nas avaliações se aproximem o mais possível dos verificados no mercado.

Essays on employment / education, investment in education and student achievement

Méthodologie: Modèle de régression quantile de variable instrumentale pour données de Panel utilisant la fonction de production partielle

Model selection and the vectorial misspecification-resistant information criterion in multivariate time series

The thesis deals with the problem of Model Selection (MS) motivated by information and prediction theory, focusing on parametric time series (TS) models. The main contribution of the thesis is the extension to the multivariate case of the Misspecification-Resistant Information Criterion (MRIC), a criterion introduced recently that solves Akaike’s original research problem posed 50 years ago, which led to the definition of the AIC. The importance of MS is witnessed by the huge amount of literature devoted to it and published in scientific journals of many different disciplines. Despite such a widespread treatment, the contributions that adopt a mathematically rigorous approach are not so numerous and one of the aims of this project is to review and assess them. Chapter 2 discusses methodological aspects of MS from information theory. Information criteria (IC) for the i.i.d. setting are surveyed along with their asymptotic properties; and the cases of small samples, misspecification, further estimators. Chapter 3 surveys criteria for TS. IC and prediction criteria are considered for: univariate models (AR, ARMA) in the time and frequency domain, parametric multivariate (VARMA, VAR); nonparametric nonlinear (NAR); and high-dimensional models. The MRIC answers Akaike’s original question on efficient criteria, for possibly-misspecified (PM) univariate TS models in multi-step prediction with high-dimensional data and nonlinear models. Chapter 4 extends the MRIC to PM multivariate TS models for multi-step prediction introducing the Vectorial MRIC (VMRIC). We show that the VMRIC is asymptotically efficient by proving the decomposition of the MSPE matrix and the consistency of its Method-of-Moments Estimator (MoME), for Least Squares multi-step prediction with univariate regressor. Chapter 5 extends the VMRIC to the general multiple regressor case, by showing that the MSPE matrix decomposition holds, obtaining consistency for its MoME, and proving its efficiency. The chapter concludes with a digression on the conditions for PM VARX models.

Bending of stochastic Kirchhoff plates on Winkler foundations via the Galerkin method and the Askey-Wiener scheme

In this paper, the method of Galerkin and the Askey-Wiener scheme are used to obtain approximate solutions to the stochastic displacement response of Kirchhoff plates with uncertain parameters. Theoretical and numerical results are presented. The Lax-Milgram lemma is used to express the conditions for existence and uniqueness of the solution. Uncertainties in plate and foundation stiffness are modeled by respecting these conditions, hence using Legendre polynomials indexed in uniform random variables. The space of approximate solutions is built using results of density between the space of continuous functions and Sobolev spaces. Approximate Galerkin solutions are compared with results of Monte Carlo simulation, in terms of first and second order moments and in terms of histograms of the displacement response. Numerical results for two example problems show very fast convergence to the exact solution, at excellent accuracies. The Askey-Wiener Galerkin scheme developed herein is able to reproduce the histogram of the displacement response. The scheme is shown to be a theoretically sound and efficient method for the solution of stochastic problems in engineering. (C) 2009 Elsevier Ltd. All rights reserved.

Quadrupole moments of radium isotopes from the 7p^2P_3/2 hyperfine structure in Ra II

The hyperfine structure and isotope shift of ^{221- 226}Ra and ^{212, 214}Ra have been measured in the ionic (Ra 11) transition 7s^2 S_{1/2} - 7p ^2 P_{3/2} (\lamda = 381.4 nm). The method of on-line collinear fast-beam laser spectroscopy has been applied using frequency-doubling of cw dye laser radiation in an external ring cavity. The magnetic hyperfine fields are compared with semi-empirical and ab initio calculations. The analysis of the quadrupole splitting by the same method yields the following, improved values of spectroscopic quadrupole moments: Q_s(^221 Ra)= 1.978(7)b, Q_s (^223 Ra)= 1.254(3)b and the reanalyzed values Q_s(^209 Ra) = 0.40(2)b, Q_s(^211 Ra) = 0.48(2)b, Q_s(^227 Ra)= 1.58(3)b, Q_s (^229 Ra) = 3.09(4)b with an additional scaling uncertainty of ±5%. Furthermore, the J-dependence of the isotope shift is analyzed in both Ra II transitions connecting the 7s^2 S_{1/2} ground state with the first excited doublet 7p^ P_{1/2} and 7p^ P_{3/2}.

Non-linear analysis of reinforced concrete plates by the boundary element method and continuum damage mechanics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudio de estructuras microtira irregulares mediante el MoM

[EN]This article presents the analysis of planar mi- crostrip structures using the electric-field integral equation. The structures are divided into irregular rectangular subdomains. Besides its describes the delta-gap voltage excitation mode to resolve the equations systems with the method of the moments.

An EFG method for the nonlinear analysis of plates undergoing arbitrarily large deformations

The applicability of a meshfree approximation method, namely the EFG method, on fully geometrically exact analysis of plates is investigated. Based on a unified nonlinear theory of plates, which allows for arbitrarily large rotations and displacements, a Galerkin approximation via MLS functions is settled. A hybrid method of analysis is proposed, where the solution is obtained by the independent approximation of the generalized internal displacement fields and the generalized boundary tractions. A consistent linearization procedure is performed, resulting in a semi-definite generalized tangent stiffness matrix which, for hyperelastic materials and conservative loadings, is always symmetric (even for configurations far from the generalized equilibrium trajectory). Besides the total Lagrangian formulation, an updated version is also presented, which enables the treatment of rotations beyond the parameterization limit. An extension of the arc-length method that includes the generalized domain displacement fields, the generalized boundary tractions and the load parameter in the constraint equation of the hyper-ellipsis is proposed to solve the resulting nonlinear problem. Extending the hybrid-displacement formulation, a multi-region decomposition is proposed to handle complex geometries. A criterium for the classification of the equilibrium`s stability, based on the Bordered-Hessian matrix analysis, is suggested. Several numerical examples are presented, illustrating the effectiveness of the method. Differently from the standard finite element methods (FEM), the resulting solutions are (arbitrary) smooth generalized displacement and stress fields. (c) 2007 Elsevier Ltd. All rights reserved.

Comparison of trends in method-specific suicide rates in Australia and England & Wales, 1968-97

Objective: To compare secular trends in method-specific suicide rates among young people in Australia and England & Wales between 1968 and 1997. Methods: Australian data were obtained from the Australian Bureau of Statistics, and for England & Wales from the Office for National Statistics. Overall and method-specific suicide rates for 15-34 year old males and females were calculated using ICD codes E950-9 and E980-9 except E988.8. Results: In both settings, suicide rates have almost doubled in young males over the past 30 years (from 16.8 to 32.9 per 100,000 in Australia and from 10.1 to 19.0 in England & Wales). Overall rates have changed little in young females. In both sexes and in both settings there have been substantial increases in suicide by hanging (5-7 fold increase in Australia and four-fold increase in England & Wales). There have also been smaller increases in gassing in the 1980s and '90s. In females, the impact of these increases on overall rates has been offset by a decline in drug overdose, the most common method in females. Conclusions: Rates of male suicide have increased substantially in both settings in recent years, and hanging has become an increasingly common method of suicide. The similarity in observed trends in both settings supports the view that such changes may have common causes. Research should focus on understanding why hanging has increased in popularity and what measures may be taken to diminish it.

Magnetic-field-induced superconductivity in layered organic molecular crystals with localized magnetic moments

The synthetic organic compound λ(BETS)2FeCl4 undergoes successive transitions from an antiferromagnetic insulator to a metal and then to a superconductor as a magnetic field is increased. We use a Hubbard-Kondo model to clarify the role of the Fe3+ magnetic ions in these phase transition. In the high-field regime, the magnetic field acting on the electron spins is compensated by the exchange field He due to the magnetic ions. This suggests that the field-induced superconducting state is the same as the zero-field superconducting state which occurs under pressure or when the Fe3+ ions are replaced by non-magnetic Ga3+ ions. We show how Hc can be extracted from the observed splitting of the Shybnikov-de Haas frequencies. Furthermore, we use this method of extracting He to predict the field range for field-induced superconductivity in other materials. We also show that at high fields the spin fluctuations of the localized spins are not important.

Age and Method-dependent Variability of Predicted Oxygen Consumption in Congenital Heart Disease

Background and Purpose. There has been a lot of debate about the use of predicted oxygen consumption to calculate pulmonary vascular resistance using the Fick principle. We therefore comparatively analyzed predicted oxygen consumption in infants and children in specific age groups, using different methods (formulas), as an attempt to better understand the usefulness and limitations of predictions. Methods and Results. Four models (LaFarge & Miettinen, Bergstra et al., Lindahl, and Lundell et al.) were used to predict oxygen consumption in 200 acyanotic patients with congenital cardiac defects aged 0-2.0, > 2.0-4.0, > 4.0-6.0, and > 6.0-8.75 years (median 2.04 years). Significant differences were observed between the age groups (P < .001) and between the methods (P < .001), not related to diagnoses. Differences between methods were more impressive in the first age group (P < .01). In patients aged 0-2.0 years, the lowest values of oxygen consumption (corresponding to the highest estimates of pulmonary vascular resistance) were obtained with the method of Lindahl; above this age, any method except that of Lundell et al. Conclusions. Although measuring oxygen consumption is always preferable, a rational use of predictions, using different methods, may be of help in situations where measurements are definitely not possible.

A method for drug infusion into the lateral median eminence and arcuate nucleus of sheep

The role of catecholamines in the control of the GnRH pulse generator is unclear as studies have relied on the use of peripheral or intracerebroventricular injections, which lack specificity in relation to the anatomical site of action. Direct brain site infusions have been used, however, these are limited by the ability to accurately target small brain regions. One such area of interest in the control of GnRH is the median eminence and arcuate nucleus within the medial basal hypothalamus. Here we describe a method of stereotaxically targeting this area in a large animal (sheep) and an infusion system to deliver drugs into unrestrained conscious animals. To test our technique we infused the dopamine agonist, quinpirole or vehicle into the medial basal hypothalamus of ovariectomised ewes. Quinpirole significantly suppressed LH pulsatility only in animals with injectors located close to the lateral median eminence. This in vivo result supports the hypothesis that dopamine inhibits GnRH secretion by presynaptic inhibition in the lateral median eminence. Also infusion of quinpirole into the medial basal hypothalamus suppressed prolactin secretion providing in vivo evidence that is consistent with the hypothesis that there are stimulatory autoreceptors on tubero-infundibular dopamine neurons. (C) 1997 Elsevier Science B.V.

Finite difference time domain (FDTD) method for modeling the effect of switched gradients on the human body in MRI

Numerical modeling of the eddy currents induced in the human body by the pulsed field gradients in MRI presents a difficult computational problem. It requires an efficient and accurate computational method for high spatial resolution analyses with a relatively low input frequency. In this article, a new technique is described which allows the finite difference time domain (FDTD) method to be efficiently applied over a very large frequency range, including low frequencies. This is not the case in conventional FDTD-based methods. A method of implementing streamline gradients in FDTD is presented, as well as comparative analyses which show that the correct source injection in the FDTD simulation plays a crucial rule in obtaining accurate solutions. In particular, making use of the derivative of the input source waveform is shown to provide distinct benefits in accuracy over direct source injection. In the method, no alterations to the properties of either the source or the transmission media are required. The method is essentially frequency independent and the source injection method has been verified against examples with analytical solutions. Results are presented showing the spatial distribution of gradient-induced electric fields and eddy currents in a complete body model.

A new method for analysing the equilibrium and time-dependent behaviour of Markovian models

Many large-scale stochastic systems, such as telecommunications networks, can be modelled using a continuous-time Markov chain. However, it is frequently the case that a satisfactory analysis of their time-dependent, or even equilibrium, behaviour is impossible. In this paper, we propose a new method of analyzing Markovian models, whereby the existing transition structure is replaced by a more amenable one. Using rates of transition given by the equilibrium expected rates of the corresponding transitions of the original chain, we are able to approximate its behaviour. We present two formulations of the idea of expected rates. The first provides a method for analysing time-dependent behaviour, while the second provides a highly accurate means of analysing equilibrium behaviour. We shall illustrate our approach with reference to a variety of models, giving particular attention to queueing and loss networks. (C) 2003 Elsevier Ltd. All rights reserved.

An appraisal of the health planning method proposed by the Pan-American Health Organization for Latin America

A brief description of the main features of the health planning technique developed by the "Centro de Estudios del Desarrollo" (CENDES) in Venezuela, and proposed by the Pan-American Health Organization for use in Latin America, is presented. This presentation is followed by an appraisal of the planning method which includes comments both upon its positive aspects and upon its negative points. Comments are also made referring to other recent publications of the WHO/PAHO on health planning. In conclusion, the CENDES technique is considered a health planning method of great potential for use especially in underdeveloped areas, the success of its application depending upon the hability of the health planners to introduce the necessary modifications to adapt to the local circunstamces.