998 resultados para [JEL:C12] Math
Resumo:
This paper adopts dynamic factor models with macro-finance predictors to test the intertemporal risk-return relation for 13 European stock markets. We identify country specific, euro area, and global macro-finance factors to determine the conditional risk and return. Empirically, the risk- return trade-off is generally negative. However, a Markov switching model documents that there is time-variation in this trade-off that is linked to the state of the economy. Keywords: Risk-return trade-off; Dynamic factor model; Macro-finance predictors; European stock markets; Markov switching model JEL Classifications: C22; G11; G12; G17
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In this paper, we scrutinize the cross-sectional relation between idiosyncratic volatility and stock returns. As a novelty, the idiosyncratic volatility is obtained by conditioning upon macro-finance factors as well as upon traditional asset pricing factors. The macro-finance factors are constructed from a large pool of macroeconomic and financial variables. Cleaning for macro-finance e§ects reverses the puzzling negative relation between returns and idiosyncratic volatility documented previously. Portfolio analysis shows that the effects from macro-finance factors are economically strong. The relation between idiosyncratic volatility and returns does not vary with the NBER business cycles. The empirical results are highly robust. Keywords: Idiosyncratic volatility puzzle; Macro-finance predictors; Factor analysis; Business cycle. JEL Classifications: G12; G14
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During the last two decades, skill mismatches have become one of the most important issues of policy concern in the EU (European Commission, 2008). Hence, the literature has stressed the necessity to reduce skill mismatches. We contribute to this literature by analyzing the impact of the transition from salaried employment to self-employment on self-reported skill mismatches. To do so, we resort to the European Community Household Panel (ECHP) covering the period 1994–2001. Using panel data, we track individuals over time and measure their self-reported skill mismatch before and after the transition. Our empirical findings indicate not only that the average self-employee is less likely to declare being skill-mismatched but also that those individuals who transit from salaried employment to self-employment reduce their probability of skill mismatches after the transition. Keywords: Self-employment, skill mismatches, salaried employment. JEL Classification: L26, J24, B23 __________________________
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This study sets out to examine the extent to which access to credit and credit rationing are influenced by the microfinance type based on the major factors determining micro, small and medium enterprises’ access to credit from microfinance institutions in the era of financial liberalization. The data for the study were gleaned from the microfinance institutions’ credit and loan records consisting of the various pieces of information provided by the borrowers in the application process. Our results are puzzling and show that credit rationing is not influenced by the microfinance types but by the individual microfinance institutions. Keywords: Microfinance, Ghana, Credit Rationing. JEL codes: G21
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The recognition of homosexual rights is a controversial issue in many countries. Spain was the third country in the world (after Netherlands and Belgium) to introduce a law recognizing homosexual marriage and adoption of children. In this paper, we examine for the first time whether schools are more hesitant to give feedback to homosexual parents during children's pre-registration period in Spain. In order to do that, we designed an internet field experiment to be conducted in schools. We created three types of fictitious couples; one heterosexual, one male homosexual and one female homosexual, and send emails to schools making sexual orientation explicit. Our results show that men homosexual couples had a significant lower probability to receive and answer than heterosexual couples (22.5 percentage points less). No statistically significant differences in the response rate were found between female homosexual and heterosexual couples. This result suggests that male homosexual couples might be penalized because of the lack of a maternal figure. Keywords: Discrimination, field experiment, schools, homosexual rights. JEL codes: H41, I20, K36
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During the first decade of this century, Spain experienced the most important economic and housing boom in its recent history. This situation led the lending industry to dramatically expand through the mortgage market. The high competition among lenders caused a dramatic lowering of credit standards. During this period, lenders operating in the Spanish mortgage market artificially inflated appraised home values in order to draw larger mortgages. By doing this, lenders gave financially constrained households access to mortgage credit. In this paper, we analyze this phenomenon for this first time. To do so, we resort to a unique dataset of matched mortgage-dwelling-borrower characteristics covering the period 2004–2010. Our data allow us to construct an unbiased measure of property’s over-appraisal, since transaction prices in our data also includes any potential side payment in the transactions. Our findings indicate that i) in Spain, appraised home values were inflated on average by around 30% with respect to transaction prices; ii) creditconstrained households were more likely to be involved in mortgages with inflated house values; and iii) a regional indicator of competition in the lending market suggests that inflated appraisal values were also more likely to appear in more competitive regional mortgage markets. Keywords: Housing demand, appraisal values, house prices, housing bubble, credit constraints, mortgage market. JEL Classification: R21, R31
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This paper estimates the determinants of productivity differentials across urban areas in Spain. To do so we resort to Spanish Social Security administrative data (MCVL) matched with workers’ fiscal information. We use two-step approach that allows us to control for the confounding effects due to the sorting of more productive workers and more productive firms in bigger cities. Our results indicate that city size is a significant determinant of productivity differentials across Spanish urban areas. We estimate an elasticity of urban agglomeration of 3.3%, which is within the range of values already observed in other countries. We also find that the level of human capital, firm size and the level of industrial specialization also matters in order explain productivity differentials across Spanish cities. Keywords: Agglomeration, wages, productivity, city size. JEL codes: R10, R23, J31
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Antimicrobial peptides offer a new class of therapeutic agents to which bacteria may not be able todevelop genetic resistance, since their main activity is in the lipid component of the bacterial cell mem-brane. We have developed a series of synthetic cationic cyclic lipopeptides based on natural polymyxin,and in this work we explore the interaction of sp-85, an analog that contains a C12 fatty acid at theN-terminus and two residues of arginine. This analog has been selected from its broad spectrum antibac-terial activity in the micromolar range, and it has a disruptive action on the cytoplasmic membrane ofbacteria, as demonstrated by TEM. In order to obtain information on the interaction of this analog withmembrane lipids, we have obtained thermodynamic parameters from mixed monolayers prepared withPOPG and POPE/POPG (molar ratio 6:4), as models of Gram positive and Gram negative bacteria, respec-tively. LangmuirBlodgett films have been extracted on glass plates and observed by confocal microscopy,and images are consistent with a strong destabilizing effect on the membrane organization induced bysp-85. The effect of sp-85 on the membrane is confirmed with unilamelar lipid vesicles of the same com-position, where biophysical experiments based on fluorescence are indicative of membrane fusion andpermeabilization starting at very low concentrations of peptide and only if anionic lipids are present.Overall, results described here provide strong evidence that the mode of action of sp-85 is the alterationof the bacterial membrane permeability barrier.
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This paper examines the extent to which innovative Spanish firms pursue improvements in energy efficiency (EE) as an objective of innovation. The increase in energy consumption and its impact on greenhouse gas emissions justifies the greater attention being paid to energy efficiency and especially to industrial EE. The ability of manufacturing companies to innovate and improve their EE has a substantial influence on attaining objectives regarding climate change mitigation. Despite the effort to design more efficient energy policies, the EE determinants in manufacturing firms have been little studied in the empirical literature. From an exhaustive sample of Spanish manufacturing firms and using a logit model, we examine the energy efficiency determinants for those firms that have innovated. To carry out the econometric analysis, we use panel data from the Community Innovation Survey for the period 2008‐2011. Our empirical results underline the role of size among the characteristics of firms that facilitate energy efficiency innovation. Regarding company behaviour, firms that consider the reduction of environmental impacts to be an important objective of innovation and that have introduced organisational innovations are more likely to innovate with the objective of increasing energy efficiency. Keywords: energy efficiency, corporate targets, innovation, Community Innovation Survey. JEL Classification: Q40, Q55, O31
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In the present paper we characterize the optimal use of Poisson signals to establish incentives in the "bad" and "good" news models of Abreu et al. [1]. In the former, for small time intervals the signals' quality is high and we observe a "selective" use of information; otherwise there is a "mass" use. In the latter, for small time intervals the signals' quality is low and we observe a "fine" use of information; otherwise there is a "non-selective" use. JEL: C73, D82, D86. KEYWORDS: Repeated Games, Frequent Monitoring, Public Monitoring, Infor- mation Characteristics.
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Traditionally, researchers have considered the innovation process as being gender neutral. However, recently some studies have begun to take gender diversity into account as a determinant of firms’ innovation. This paper aims to analyse how the effect of gender diversity on innovation output at firm level is sensitive to team size. Using the Spanish PITEC (Panel de Innovación Tecnológica) from 2007 to 2012 for innovative manufacturing and service firms, we estimate a multivariate probit model to analyse how gender diversity both in R&D teams and in the total workforce affect product, process, marketing and organizational innovations. Our results show that gender-diverse teams increase the probability of innovating, and this capacity is positively related team size. Gender diversity, in both the R&D department and the total workforce, has a larger positive impact on the probability of carrying out product and organizational innovations in larger teams than it does in smaller teams. This effect is less clear-cut in the case of marketing and process innovation, where the impact is only significant for micro and small firms. Finally, size effects are of greater importance when we distinguish between the manufacturing and service sectors. JEL Code: O30, O31, J16
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This paper analyses the impact of Free Trade Agreements (FTAs) on Middle East and North African Countries (MENA) trade for the period 1994-2010. The analysis distinguishes between industrial and agricultural trade to take into account the different liberalisation schedules. An augmented gravity model is estimated using up-to-date panel data techniques to control for all time-invariant bilateral factors that influence bilateral trade as well as for the so-called multilateral resistance factors. We also control for the endogeneity of the agreements and test for self-selection bias due to the presence of zero trade in our sample. The main findings indicate that North-South-FTAs and South-South- FTAs have a differential impact in terms of increasing trade in MENA countries, with the former being more beneficial in terms of exports for MENA countries, but both showing greater global market integration. We also find that FTAs that include agricultural products, in which MENA countries have a clear comparative advantage, have more favourable effects for these countries than those only including industrial products. JEL code: F10, F15
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The aim of this study is to analyze the transformation of Primary School teachers’ conceptions about mathematical problem solving. We performed a study with 18 teachers from three public schools: in each class (from 1º to 6º) there were two interventions, and we were interviewed teachers before and after them. The results have show identified changes in: 1) teacher’s expectations about students’ abilities; classroom management; perception of diversity; mathematical strategies used by students; communication in the classroom; causes of the problems encountered; and relevance process of problem solving in mathematics teaching. The transformation of teachers’ conceptions is due to the following factors: a) awareness of the practice; b) systematic reflection; c) the contrast between different ways to work solving problems in math class
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A liquid chromatography method was developed and validated for the determination of phenobarbital in human plasma using phenytoin as internal standard. The drugs were extracted from plasma by liquid-liquid extraction and separated isocratically on a C12 analytical column, maintained at 35 ºC, with water:acetonitrile:methanol (58.8:15.2:26, v/v/v) as mobile phase, run at a flow rate of 1.2 mL/min with detection at 205 nm. The method was linear in the range of 0.1-4 μg/mL (r²=0.9999) and demonstrated acceptable results for the precision, accuracy and stability studies. The method was successfully applied for the bioequivalence study of two tablet formulations (test and reference) of phenobarbital 100 mg after single oral dose administration to healthy human volunteers.
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The electronic, structural properties and elastic constants of the wurtzite phase of zinc oxide, ZnO, was investigated using computer simulation at Density Functional Theory level, with B3LYP hybrid functional and Hartree-Fock methodology. The electronic properties as well the band energy was investigated through the analysis of the band structures and density of states (DOS), and the mechanical properties was studied through the calculus of the elastic constants C11, C33, C44, C12 e C13. The results are in good agreement with experimental data found in the literature and in accordance with results obtained by another theoretical methodology.