Digging Out the PPP Hypothesis: an Integrated Empirical Coverage

We use several popular tests to test the validity of the Purchasing Power Parity (PPP) hypothesis. In particular, we analyze four classes of tests { standard univariate unit root tests, co-integration, panel unit root tests and unit root tests for nonlinear frameworks {, for a dataset consisting of 20 bilateral exchange rates. Through this approach, we ascertain the eectiveness of each methodology in assessing the validity of PPP. Overall, our results suggest little evidence to support PPP. Among the conducted tests, the panel analysis of nonstationarity idiosyncratic and common components provides the richest insights by disentangling the possible sources of non-stationarity of real exchange rates. The relevance of using price indexes with dierent characteristics is also pinpointed.PPP; Real exchange rate; Unit roots; Co-integration; Panel; Nonlinear models; Cross-sectional dependence

Estudio de diversas especies de los géneros Trachelomonas y Strombomonas (Euglenophyta).

Se estudian siete especies de Euglenofíceas loricadas, 2 pertenecientes al género Strombomonas y5 de Trachelomonas. Se analiza la microarquitectura de la lórica a microscopio óptico y electrónico de barrido, describiendo los elementos ornamentales de cada especie.Destacamos el estudio de tres poblaciones de Trachelomonas, dos de ellas incluidas provisionalmente en T. nigra y T. similis respectivamente, mientras que en la tercera: Trachelomonas sp., con una gran variabilidad morfológica de la lórica, destaca la existencia de un anillo de perforaciones que se disponen alrededor del poro flagelarSeven species of Euglenophyceae with lorica (2 Strombomonas and 5 Trachelomonas) haven been studied. We analyzed their lorica microarchitecture by means of ligh microscopy and scanning electron microscopy, enumerating their different ornamental elements. We stand out the study of three population of Trachelomonas, two of them are provisionally included in T. nigra and T. similis respectively. The third one: Trachelomonas sp. show a large morphological variability with only one common ornamental character within of the population: a ring of perforations around the flagellum pore

Comparative study of the pathogenicity of seabed isolates of Fusarium equiseti and the effect of the composition of the mineral salt medium and temperature on mycelia growth

The pathogenicity of seven strains of Fusarium equiseti isolated from seabed soil was evaluated on different host plants showing pre and post emergence damage. Radial growth of 27 strains was measured on culture media previously adjusted to different osmotic potentials with either KCl or NaCl (-1.50 to - 144.54 bars) at 15º, 25º and 35º C. Significant differences and interactive effects were observed in the response of mycelia to osmotic potential and temperature

Lixiviação de potássio para avaliação do potencial fisiológico de sementes de milho

Seed production usually requires fast decisions to improve the efficacy of seed handling during harvesting, processing and storage. Seed technologists have focused on the development or improvement of procedures which allow rapid and consistent identification of higher quality seed lots. This research verified the effectiveness of the potassium leachate test on the evaluation of the physiological potential of maize seeds in comparison to recommended seed vigor tests. Five seed lots of the hybrid Avant were submitted to the potassium leachate, standard germination, first count, accelerated aging, electrical conductivity, field emergence and cold tests. The amount of potassium leachate was determined after seed imbibition for 30, 60, 90, 120, 150 and 180 minutes, at 25°C; a flame photometer adjusted to 50 mug K+ mL-1 pattern and reading 50 was used to determine the amount of leached potassium. The potassium leachate test consistently ranked the seed lots according to their physiological quality in comparison to other tests, and is a new alternative test for maize seed quality control programs.A necessidade freqüente da tomada de decisões rápidas, principalmente nas etapas de colheita, processamento e comercialização é habitual durante o processo de produção de sementes de várias espécies, dentre elas o milho. Consequentemente, a pesquisa em tecnologia de sementes tem procurado desenvolver ou aperfeiçoar testes que possibilitem avaliar, com eficiência, o potencial fisiológico das sementes, em período de tempo relativamente curto. O presente trabalho teve como objetivo verificar a potencialidade do teste de lixiviação de potássio, para avaliação do vigor de sementes de milho; cinco lotes do híbrido Avant foram submetidos a esse teste, cuja eficiência foi comparada à dos testes de germinação, primeira contagem de germinação, envelhecimento acelerado, frio, condutividade elétrica e emergência de plântulas em campo, recomendados para sementes de milho. A quantidade de potássio exsudado foi determinada em fotômetro de chama (padrão 50 mig K+ mL-1 ajustado para leitura 50), após 30, 60, 90, 120, 150 e 180 minutos de embebição, a 25°C. O teste de lixiviação de potássio foi considerado eficiente para separação dos lotes em diferentes níveis de vigor, constituindo alternativa promissora para avaliação do potencial fisiológico de sementes de milho; essa possibilidade contribui para a obtenção rápida de informações balizadoras de programas de controle de qualidade pós-colheita

Joint degrees in cooperative e-learning environments

En los modelos educativos tradicionales es común observar el desarrollo de convenios de cooperación entre diversas organizaciones para la realización de titulaciones conjuntas, en los cuales, cada organización aporta a su contraparte recursos de aprendizaje, docentes y/o estudiantes, buscando el logro de las competencias educativas con esfuerzos comunes. En la sociedad del conocimiento, las tecnologías de la información y de las comunicaciones (TIC) aportan ventajas competitivas que facilitan los espacios de cooperación para el desarrollo de titulaciones conjuntas; sin embargo, se observa que existen limitaciones de índole tecnológica, que dificultan la realización de estos espacios de cooperación. El presente trabajo analiza los ambientes cooperativos para la realización de titulaciones conjuntas, describiendo factores adversos que inhiben estos espacios y propone alternativas de solución a la problemática observada.In traditional education models, we can frequently observe the development of cooperation agreements between diverse organisations for the undertaking of joint degrees, whereby each organisation provides its counterpart with learning resources, faculty and/or students in order to achieve educational competences through joint efforts. In the knowledge society, Information and Communication Technologies (ITC) provide competitive advantages that facilitate areas of cooperation for the development of joint degrees. However, technological limitations exist that hinder the creation of such areas of cooperation. This work analyses the cooperative environs for the undertaking of joint degrees and describes adverse factors that inhibit such areas, as well as proposing alternative solutions to the problems observed

Limiting thickness estimation in polycarbonate lenses injection using CAE tools

Some commercial software packages that simulate injection processes are available. It is possible to design moulds and to optimise the processes by using computer-aided engineering (CAE) tools. In addition, we employ C-MOLD, one of the best commercial packages, to determine the limiting thickness in polycarbonate lenses manufactured by injection. In this work we use a simple geometry to study the variation of different magnitudes as a function of the lowest thickness in biconcave and biconvex lenses. The parameters studied are the variation of temperature, pressure and piece mass during the filling time, air traps, melt lines and weld lines. The flow problem of the plastic in the mould is very different for biconcave and biconvex lenses. While the limiting thickness is in the centre for the biconcave lens, the perimeter is the limiting zone for the flow in the biconvex lens. For both geometries, however, the minimum thickness is limited by a mechanical and an aesthetic factor. If we take into account the variation of temperature, pressure and mass with minimum thickness, the mechanical limiting thickness can be estimated as 500 μm. But, if we also consider the evolution of the air traps and the melt and weld lines, which greatly influence the aesthetic factor, the resulting limiting thickness is 650 μm in the centre of biconcave lenses and 500 μm in the peripheric area of biconvex lenses

Bayesian smoothing for time-varying extremal dependence

This work was supported by CIDMA (Universidade de Aveiro) and is funded by the Fundação para a Ciência e a Tecnologia, I.P. (FCT, Funder ID: 50110000187) under Grants https://doi. org/10.54499/UIDB/04106/2020 and https://doi.org/10.54499/UIDP/04106/2020.We propose a Bayesian time-varying model that learns about the dynamics governing joint extreme values over time. Our model relies on dual measures of time-varying extremal dependence, that are modelled via a suitable class of generalized linear models conditional on a large threshold. The simulation study indicates that the proposed methods perform well in a variety of scenarios. The application of the proposed methods to some of the world’s most important stock markets reveals complex patterns of extremal dependence over the last 30 years, including passages from asymptotic dependence to asymptotic independence.proofpublishe

Ownership structure and performance: A comparison of different corporate governance systems

[EN] This paper analyses how the main institutional factors characterizing corporate governance systems around the world affect the relationship between ownership structure and firm performance. Our analysis gives rise to the following remarks. First, ownership concentration and insider ownership levels are determined by several institutional features such as investor protection, development of capital markets, activity of the market for corporate control, and effectiveness of boards. Second, the relationship between ownership concentration and performance is not directly affected by these institutional factors. Third, there is, however, a direct influence of corporate governance characteristics on the relationship between insider ownership and performance

Novel Microscopic Mechanism of Intermixing during Growth on Soft Metallic Substrates

Generic computer simulations using empiric interatomic potentials suggest a new, collective mechanism that could be responsible for mixing at heteroepitaxial interfaces. Even if single adsorbate atoms diffuse by hopping on the substrate surface and do not mix at the terraces, two-dimensional islands formed by nucleation may become unstable above a certain critical size and explode upwards forming clusters of several atomic layers. This process is accompanied by strong distortions of the underlying atomic layers, and on soft materials it can result in surface etching and incorporation of substrate atoms into the islands.Fil: Gomez, Liliana Maria. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Slutzky, Claudia Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Ferron, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: de la Figuera, J.. Sandia National Laboratories; Estados UnidosFil: Camarero, J.. Universidad Autónoma de Madrid; EspañaFil: Vazquez de Parga, A.. Universidad Autónoma de Madrid; EspañaFil: de Miguel, J.J.. Universidad Autónoma de Madrid; EspañaFil: Miranda, R.. Universidad Autónoma de Madrid; Españ