Entrepreneurial skills and over-education five years later. A comparison between Spain and the Netherlands

[cat] El fenòmen de la sobre-educació és freqüent i persistent a molts països. En aquest article estudiem el paper de les habilitats emprenedores en evitar la sobre-educació a la primera feina, i en sortir d’una situació de sobre-educació cinc anys després. Comparem els resultats d’Espanya i Holanda, dos països que difereixen en el seu sistema educatiu i mercat de treball. Els resultats mostren que les habilitats emprenedores ajuden a evitar i/o sortir de la sobre-educació només a Espanya, on el sistema educatiu és més flexible i menys vinculat amb el mercat de treball. En general, els nostres resultats recolzen les polítiques que promocionen el desenvolupament d’habilitats emprenedores al sistema educatiu espanyol.

Market Index Biases and Minimum Risk Indices

Markets, in the real world, are not efficient zero-sum games where hypotheses of the CAPM are fulfilled. Then, it is easy to conclude the market portfolio is not located on Markowitz"s efficient frontier, and passive investments (and indexing) are not optimal but biased. In this paper, we define and analyze biases suffered by passive investors: the sample, construction, efficiency and active biases and tracking error are presented. We propose Minimum Risk Indices (MRI) as an alternative to deal with to market index biases, and to provide investors with portfolios closer to the efficient frontier, that is, more optimal investment possibilities. MRI (using a Parametric Value-at-Risk Minimization approach) are calculated for three stock markets achieving interesting results. Our indices are less risky and more profitable than current Market Indices in the Argentinean and Spanish markets, facing that way the Efficient Market Hypothesis. Two innovations must be outlined: an error dimension has been included in the backtesting and the Sharpe"s Ratio has been used to select the"best" MRI

Improving Pitch Tracking Performance in Hard Noise Conditions by a Preprocessing Based on Mathematical Morphology

In this paper we show how a nonlinear preprocessing of speech signal -with high noise- based on morphological filters improves the performance of robust algorithms for pitch tracking (RAPT). This result happens for a very simple morphological filter. More sophisticated ones could even improve such results. Mathematical morphology is widely used in image processing and has a great amount of applications. Almost all its formulations derived in the two-dimensional framework are easily reformulated to be adapted to one-dimensional context

Reliable misrepresentation and teleosemantics

Mendelovici (forthcoming) has recently argued that (1) tracking theories of mental representation (including teleosemantics) are incompatible with the possibility of reliable misrepresentation and that (2) this is an important difficulty for them. Furthermore, she argues that this problem commits teleosemantics to an unjustified a priori rejection of color eliminativism. In this paper I argue that (1) teleosemantics can accommodate most cases of reliable misrepresentation, (2) those cases the theory fails to account for are not objectionable and (3) teleosemantics is not committed to any problematic view on the color realism-antirealism debate

Tracking Invasion Histories in the Sea: Facing Complex Scenarios Using Multilocus Data

In recent years, new analytical tools have allowed researchers to extract historical information contained in molecular data, which has fundamentally transformed our understanding of processes ruling biological invasions. However, the use of these new analytical tools has been largely restricted to studies of terrestrial organisms despite the growing recognition that the sea contains ecosystems that are amongst the most heavily affected by biological invasions, and that marine invasion histories are often remarkably complex. Here, we studied the routes of invasion and colonisation histories of an invasive marine invertebrate Microcosmus squamiger (Ascidiacea) using microsatellite loci, mitochondrial DNA sequence data and 11 worldwide populations. Discriminant analysis of principal components, clustering methods and approximate Bayesian computation (ABC) methods showed that the most likely source of the introduced populations was a single admixture event that involved populations from two genetically differentiated ancestral regions - the western and eastern coasts of Australia. The ABC analyses revealed that colonisation of the introduced range of M. squamiger consisted of a series of non-independent introductions along the coastlines of Africa, North America and Europe. Furthermore, we inferred that the sequence of colonisation across continents was in line with historical taxonomic records - first the Mediterranean Sea and South Africa from an unsampled ancestral population, followed by sequential introductions in California and, more recently, the NE Atlantic Ocean. We revealed the most likely invasion history for world populations of M. squamiger, which is broadly characterized by the presence of multiple ancestral sources and non-independent introductions within the introduced range. The results presented here illustrate the complexity of marine invasion routes and identify a cause-effect relationship between human-mediated transport and the success of widespread marine non-indigenous species, which benefit from stepping-stone invasions and admixture processes involving different sources for the spread and expansion of their range.

Integrating quantitative proteomics and metabolomics in a cellular model of diabetic retinopathy

Diabetic retinopathy is the leading cause of visual loss in individuals under the age of 55. Most investigations into the pathogenesis of diabetic retinopathy have been concentrated on the neural retina since this is where clinical lesions are manifested. Recently, however, various abnormalities in the structural and secretory functions of retinal pigment epithelium that are essential for neuroretina survival, have been found in diabetic retinopathy. In this context, here we study the effect of hyperglycemic and hypoxic conditions on the metabolism of a human retinal pigment epithelial cell line (ARPE-19) by integrating quantitative proteomics using tandem mass tagging (TMT), untargeted metabolomics using MS and NMR, and 13C-glucose isotopic labeling for metabolic tracking. We observed a remarkable metabolic diversification under our simulated in vitro hyperglycemic conditions of diabetes, characterized increased flux through polyol pathways and inhibition of the Krebs cycle and oxidative phosphorylation. Importantly, under low oxygen supply RPE cells seem to consume rapidly glycogen storages and stimulate anaerobic glycolysis. Our results therefore pave the way to future scenarios involving new therapeutic strategies addressed to modulating RPE metabolic impairment, with the aim of regulating structural and secretory alterations of RPE. Finally, this study shows the importance of tackling biomedical problems by integrating metabolomic and proteomics results.

Combining stable isotope analyses and geolocation to reveal kittiwake migration

Determining migratory strategies of seabirds is still a major challenge due to their relative inaccessibility. Small geolocators are improving this knowledge, but not all birds can be tracked. Stable isotope ratios in feathers can help us to understand migration, but we still have insufficient baseline knowledge for linking feather signatures to movements amongst distinct water masses. To understand the migration strategies of kittiwakes Rissa tridactyla and the link between stable isotopes in feathers and the areas in which these were grown, we tracked 6 kittiwakes from Hornøya, Norway, with light level geolocators over 1 yr. Then we analysed the stable isotopes of carbon and nitrogen in their 1st and 7th primary feathers as well as in the 1st, 3rd, 5th, 7th and 10th primaries of 12 birds found freshly dead in the same breeding colony. After breeding, all tracked birds moved east of the Svalbard Archipelago and subsequently migrated to the Labrador Sea. Thereafter, birds showed individual variation in migration strategies: 3 travelled to the NE Atlantic, whereas the others remained in the Labrador Sea until the end of the wintering period. Changes in stable isotope signatures from the 1st to the 10th primary feathers corresponded well to the sequence of movements during migration and the area in which we inferred that each feather was grown. Thus, by combining information on moult patterns and tracking data, we demonstrate that stable isotope analysis of feathers can be used to trace migratory movements of seabirds.

Trans-equatorial migration and mixing in the wintering areas of a pelagic seabird

Despite increasing interest in long-distance migration, the wintering areas, migration corridors, and population mix in winter quarters of most pelagic marine predators are unknown. Here, we present the first study tracking migration movements of shearwaters through the non-breeding period. We used geolocators (global location sensing [GLS] units based on ambient light levels) to track 22 Cory's shearwaters (Calonectris diomedea) breeding in three different areas. Most birds wintered in one or more of three relatively small areas, all clearly associated with major coastal upwelling systems of the tropical and south Atlantic. Trans-equatorial movements were dominated by prevailing trade winds and westerlies, while calm, oligotrophic areas were avoided. Breeding populations clearly differed in their preference amongst the three major wintering areas, but showed substantial mixing. This illustrates the exceptional value of GLS, not only for determining and describing the influence of oceanographic features on migration patterns, but also for assessing population mix in winter quarters. This knowledge is essential to understanding the impacts of population-level threats, such as longlining, offshore windfarms, and oil spills on multiple breeding sites, and will be critical in devising conservation policies that guarantee the sustainable exploitation of the oceans.

Metals and Selenium as bioindicators of geographic and trophic segregation in Giant Petrels Macronectes spp.

We analysed concentrations of cadmium, lead, mercury and selenium in blood from males and females of the 2 sibling species of giant petrels, the northern Macronectes halli and the southern M. giganteus, breeding sympatrically at Bird Island (South Georgia, Antarctica). Blood samples were collected in 1998 during the incubation period, from 5 November to 10 December. Between species, cadmium and lead concentrations were significantly higher for northern than for southern giant petrels, which probably resulted from northern giant petrels wintering in more polluted areas (mainly on the Patagonian Shelf and Falkland Islands) compared to southern giant petrels (wintering mainly around South Georgia and the South Sandwich Islands). Between sexes, cadmium concentrations were significantly higher for females than for males in both species, corresponding to the more pelagic habits of females compared to the more scavenging habits of males. Lead and cadmium concentrations in circulating blood decreased significantly over the incubation period, suggesting that when breeding at Bird Island, exposure to the source of pollution had ended, and these metals had been cleared from the blood and excreted, or rapidly transferred to other tissues. Association of lead and cadmium with a common source of pollution was further corroborated by a significant positive correlation between the levels of the 2 elements found. Mercury levels were similar between the species, but showed an opposite trend between sexes, with males showing higher levels than females in northern giant petrels, and the opposite was true in southern giant petrels, with no changes throughout incubation. Selenium levels were similar between sexes, but significantly greater for northern than for southern giant petrels. Moreover, there was a significant increase in the selenium levels over the incubation period in northern giant petrels. Age of adult birds did not affect metal concentrations. Coefficients of variation of metal levels were consistently lower for northern than for southern giant petrels, particularly for mercury, suggesting that the former species is more dietary specialised than the latter. Contaminant analyses, when combined with accurate information on seabird movements, obtained through geolocation or satellite tracking, help us to understand geographic variation of pollution in the marine environment.

Tracking of physical activity during adolescence: The 1993 Pelotas Birth Cohort, Brazil

Objective: To analyze physical activity during adolescence in participants of the 1993 Pelotas Birth Cohort Study, Brazil. Methods: Data on leisure time physical activity at 11, 15, and 18 years of age were analyzed. At each visit, a cut-off point of 300 min/week was used to classify adolescents as active or inactive. A total of 3,736 participants provided data on physical activity at each of the three age points. Results: A significant decline in the proportion of active adolescents was observed from 11 to 18 years of age, particularly among girls (from 32.9% to 21.7%). The proportions of girls and boys who were active at all three age points were 28.0% and 55.1%, respectively. After adjustment for sex, economic status, and skin color, participants who were active at 11 and 15 years of age were 58.0% more likely to be active at 18 years of age compared with those who were inactive at 11 and 15 years of age. Conclusions: Physical activity declined during adolescence and inactivity tended to track over time. Our findings reinforce the need to promote physical activity at early stages of life, because active behavior established early tends to be maintained over time.