2,221 research outputs found
Territory and Sustainable Tourism Development: a Space-Time Analysis on European Regions
In the long run, tourism competitiveness depends on the sustainable use of territorial assets: the differentiation of destinations depends on the integration of cultural and natural resources into the tourism supply, but also on their preservation over time. The link between competitiveness and sustainability is the staring point for our analysis of the relationships between regional tourism competitiveness, the dynamics of tourism demand and investment and the existence of natural resources and cultural assets in European regions, by using advanced spatial econometric techniques. Despite the close relationship between tourism activities and the characteristics of the territory, the application of methods of spatial analysis methods in tourism studies is still scarce and the results of this work clearly show their potential for this field of research. Among the main findings of this paper, it was observed that natural resources do not have the expected positive impacts on regional tourism competitiveness and that European regions with more abundant natural resources are often developing unsustainable forms of mass tourism, with low value added and scarce benefits for the host communities. The existence of spatial correlation effects suggests that positive spillovers arising from tourism dynamics in neighbourhood regions prevail over potential negative effects related to the competition between destinations. Policy and managerial implications of these results are discussed and further research questions are suggested
The fractional volatility model : no-arbitrage, leverage and completeness
When the volatility process is driven by fractional noise one obtains a model which is consistent with the empirical market data. Depending on whether the stochasticity generators of log-price and volatility are independent or are the same, two versions of the model are obtained with different leverage behaviors. Here, the no-arbitrage and completeness properties of the models are rigorously studied
Measuring wage inequality under right censoring
In this paper we investigate potential changes which may have occurred over
the last two decades in the probability mass of the right tail of the wage
distribution, through the analysis of the corresponding tail index. In
specific, a conditional tail index estimator is introduced which explicitly
allows for right tail censoring (top-coding), which is a feature of the widely
used current population survey (CPS), as well as of other surveys. Ignoring the
top-coding may lead to inconsistent estimates of the tail index and to under or
over statements of inequality and of its evolution over time. Thus, having a
tail index estimator that explicitly accounts for this sample characteristic is
of importance to better understand and compute the tail index dynamics in the
censored right tail of the wage distribution. The contribution of this paper is
threefold: i) we introduce a conditional tail index estimator that explicitly
handles the top-coding problem, and evaluate its finite sample performance and
compare it with competing methods; ii) we highlight that the factor values used
to adjust the top-coded wage have changed over time and depend on the
characteristics of individuals, occupations and industries, and propose
suitable values; and iii) we provide an in-depth empirical analysis of the
dynamics of the US wage distribution's right tail using the public-use CPS
database from 1992 to 2017
Measuring wage inequality under right censoring
A conditional tail index estimator is introduced which explicitly allows for right-tail censoring (top-coding). We show that the factor values used to adjust top-coded wages have changed over time and depend on individuals' characteristics, occupations and industries, and propose suitable values. Specifically, contrasting the results of our approach with those of a conservative fixed adjustment factor of 1.5 (used in the literature), suggests that wage inequality in 2017 measured with the Gini coefficient is larger than that suggested by the fixed adjustment factor.info:eu-repo/semantics/publishedVersio
Electrochemical generation of hydroxyl radicals for protein oxidation studies
In the last decades, different studies shown that the increase in oxidative stress is associated with the risk factors implicated in the pathophysiology of many chronic diseases. Therefore it is important to evaluate the role that hydroxyl radicals-mediated damage may play in major human disorders. Proteins are important targets as they compose ca. 70% of cells. To understand the impact of specific modifications on protein function, stability and toxicity resulting of the damage caused by the attacked of these radicals it is important to characterize the proteins oxidation products obtained from assays where hydroxyl radicals are generated by clean processes [1]. In spite of radiolysis and photolysis are adequate for this purpose they are not accessible for most laboratories. On the other hand, Fenton-like reactions are quite accessible but have many drawbacks associated to the use of chemical precursors that can bias results [2]. In this context the electrochemical generation of hydroxyl radical can provide an alternative method that is both clean and accessible, were these radicals are formed as intermediate in the oxidation of water to produce oxygen. This reaction can be accomplished in different electrode materials such as of boron doped diamond electrodes (BDD) and platinum (Pt), among others [3].
In this work we present a study were the oxidation of BSA is conducted in different experimental conditions, including the anode material (BDD and Pt), current density and electrolytes. The extension of BSA oxidation was monitored by the quantification of carbonyl groups formed during the protein oxidation and the cleavage extension, evaluated by gel electrophoresis method (SDS-PAGE).Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/64189/2009
Geometric contrast feature for automatic visual counting of honey bee brood capped cells
Assessment of honey bee colony strength by measuring adults or brood is often required for ecological studies. The brood has typically been estimated through a subjective mode (Lieberfelder method), although it can also be objectively determined by counting (manually or automatically) the brood cells (capped or uncapped) from digital images. The manual counting of capped cells is highly prone to errors and a time-consuming and tedious task. An automatic way to accomplish that task allows reducing those drawbacks. The main challenge for developing an automatic method is, however, the presence of intraclass color variation; it is not possible to make a reliable detection based just on the pixel color presented by the capped cells. While several researchers are using the Hough transform to solve that problem, at certain light, noise, and surface conditions the automatic detection fails. After carefully observing capped cell regions of several combs, we identified a set of geometrical relations that could be used to build a consistent contrast feature. That feature is the key to detect the capped cells with a high accuracy in our work. A functional optimizer is performing a searching on the image looking for the locations that maximize the contrast on that feature. Our experimental results are showing a good detection rate (over 96%), despite the wide intraclass color variation.
This research is funded through the 2013-2014 BiodivERsA/FACCE-JPI Joint call for research proposals, with the national funders FCT (Portugal), CNRS (France), and MEC (Spain).info:eu-repo/semantics/publishedVersio
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In situ degradation of YSZ and YSZ + Al2O3 electrolytes of sensors used in glass melting furnaces
This work reports on the degradation of pure YSZ and YSZ +10 wt% alumina composite electrolytes by exposure to the atmosphere of a heat recovery chamber of an industrial glass furnace, at a temperature around 1300 °C. Microstructural observations and impedance spectroscopy measurements were used to evaluate the corrosion effects. YSZ samples directly placed in the sidewalls and intimately exposed to the dusts and volatiles in the atmosphere show strong corrosion effects after short periods. These samples present large amounts of a glassy phase in the intergranular region, containing the same elements as the common batch with inclusion of volatile species from the fuel. At the same time, the average composition of YSZ grains remains almost unchanged. Effects on the electrical properties are obviously stronger in the intergranular response, as confirmed by changes in the typical relaxation frequency.
The protection of samples and/or their careful placement in the furnace strongly inhibit the corrosion process. The effectiveness of alumina addition to the YSZ electrolyte in increasing its corrosion resistance was only tested in protected samples, where the corrosion is less severe. For this reason, the expected benefits of this incorporation were found almost irrelevant
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