A hybrid ARIMA and artificial neural networks model to forecast particulate matter in urban areas: The case of Temuco, Chile

Air quality time series consists of complex linear and non-linear patterns and are difficult to forecast. Box-Jenkins Time Series (ARIMA) and multilinear regression (MLR) models have been applied to air quality forecasting in urban areas, but they have limited accuracy owing to their inability to predict extreme events. Artificial neural networks (ANN) can recognize non-linear patterns that include extremes. A novel hybrid model combining ARIMA and ANN to improve forecast accuracy for an area with limited air quality and meteorological data was applied to Temuco, Chile, where residential wood burning is a major pollution source during cold winters, using surface meteorological and PM10 measurements. Experimental results indicated that the hybrid model can be an effective tool to improve the PM10 forecasting accuracy obtained by either of the models used separately, and compared with a deterministic MLR. The hybrid model was able to capture 100% and 80% of alert and pre-emergency episodes, respectively. This approach demonstrates the potential to be applied to air quality forecasting in other cities and countries

Achievements of a Bilingual Policy: The Colombian Journey

The Colombian journey to become a country with an educational system that develops bilingual skills in students began in 1979. More recently, Colombia National Ministry of Education presented Colombia’s National Bilingualism Program 2004–2019, a policy that recognized for the first time that mastering English was a matter of advantages in competitiveness for the country. Two important goals were established under this policy for 2014. First, 40% of secondary graduates should achieve at least an intermediate level—B1or threshold or independent user following the Common European Framework of Reference for Languages (CEFRL). Second, 20% of Bachelor degree (under) graduates should achieve at least a vantage or upper intermediate—B2 level. A descriptive approach was applied to the data and it was found that the neither goal was met. The impact of the different programs implemented should be evaluated, so goals proposed for 2025 can be achieved

Decoherence in an accelerated universe

In this paper we study the decoherence processes of the semiclassical branches of an accelerated universe due to their interaction with a scalar field with given mass. We use a third quantization formalism to analyze the decoherence between two branches of a parent universe caused by their interaction with the vaccum fluctuations of the space-time, and with other parent unverses in a multiverse scenario.Comment: 11 pages, 2 figure

Financial Education from school age - analysis in small Municipalities in Colombia / Educação financeira desde a idade escolar - análise em pequenos Municípios da Colômbia

Financial education is an aspect that has acquired great importance in the economic development of countries, and its inclusion in basic and secondary education programs can bring benefits to the society and the economy of a country. This being the case, the financial education should not be an option but a necessary condition in the training processes, even more because we are facing generations that think in a different way, whose priorities have changed compared to those of previous generations. The measurement of the level of competences in finance has acquired such importance that different organizations such as S&P or the OECD have developed instruments for this purpose. Colombia shows a low level of development in these measurements, a fact that justifies this research with which it is sought to establish the real level of basic knowledge in finance on the part of students who are about to graduate from high scholl and enroll higher education or be integrated into the labor world, in the municipalities of Chía and Sopó, near Bogotá, capital of Colombia

Performance of baited underwater video for estimating abundance of spiny lobsters

Baited underwater video (BUV) is increasingly been used to sample fish species but lobsters are potentially good candidates for sampling with BUV as they are attracted to bait due to their scavenging habits. We built a cost effective BUV system to sample Palinurus elephas, a Mediterranean deep-water lobster. Camera deployments were performed at the Columbretes Islands MPA. We compared the standard method of estimating abundance with BUV, by recording the maximum number (Nmax) of individuals at any one point on the tape, with the estimated true number of lobsters having attended the bait (Ntot). We found it possible to use images of unique body patterns for identifying individuals over time. The highest Nmax - 6 lobsters in the field of view - was lower than the total number of lobsters estimated by identifying individuals in all three recordings - total of 7 to 11 individual lobsters. This highlights the extent of underestimation of abundance derived from Nmax estimates (Mean Nmax = 4 as opposed to Ntot= 8.6 by tracking individuals). Measurement of lobster size was trouble free with the coefficient of variation of all measurements being low. However, all measurements were biassed due to calibration problems related to lobster height above the bait bag. Taking into account the relatively low cost of the units, coupled with the ability of this system to work to depths impractical for visual surveys, we propose that this non-intrusive method will be useful for sampling deep water lobster

First V-notching experiment in the spiny lobster Palinurus elephas

V-notching tagging has been practiced for decades in juveniles and ovigerous females of the clawed lobsters Homarus americanus and H. gammarus as an effective conservation strategy in several European and US fisheries. For the first time a V-notch experimental study was conducted with the spiny lobster Palinurus elephas with the aims of: 1) assess survival of notched versus unnotched lobsters, 2) assess differences in the incidence of shell disease of notched and unnotched lobsters, and 3) assess the rate of notch loss (tag retention) with respect to molt frequency. A total of 36 wild young adults were housed in a tank of 10000 litres separated in three replicates of 12 lobsters each one. Half of individuals of each replicate were marked with a v-notch (side 1 cm long). Tank environmental conditions (temperature, salinity and dissolved oxygen) were controlled to mimic conditions in the wild. The experiment lasted 20 months. There were no significant differences in survival or health conditions of notched and unnotched specimens. After 15 months, all the indivudals had completed two molts and five of them have undergone the third one. After the second molt on average 25% of the notched area has been overgrown and lobsters with the third molt have overgrown 45% of the notched area. The performance of area, width and height of the V-notch tab for regulatory purposes are discusse

Diversidad de polen de Pinus aerovagante y patrón anual de su polinización en España

The authors wish to thank to different projects and entities for financing this study: COST ES0603 EUPOL; Laboratorios LETI S.A.; Proyecto EOLO-PAT; European Commission for «ENV4-CT98-0755»; Spanish Ministry of Science and Technology I+D+I for «AMB97-0457-CO7-021», «REN2001-10659-CO3-01», «BOS2002-03474», «CGL2004-21166-E», «CGL2005-07543/CLI», «CGL2009-11205» and CONSOLIDER CSD2007_00067 GRACCIE; Andalusian Government for «RNM-5058»; and Catalan Government AGAUR for «2002SGR00059», «2005SGR00519» and «2009SGR1102»

Understory plant communities show resistance to drought, hurricanes, and experimental warming in a wet tropical forest

Global climate change has led to rising temperatures and to more frequent and intense climatic events, such as storms and droughts. Changes in climate and disturbance regimes can have non-additive effects on plant communities and result in complicated legacies we have yet to understand. This is especially true for tropical forests, which play a significant role in regulating global climate. We used understory vegetation data from the Tropical Responses to Altered Climate Experiment (TRACE) in Puerto Rico to evaluate how plant communities responded to climate warming and disturbance. The TRACE understory vegetation was exposed to a severe drought (2015), 2 years of experimental warming (4°C above ambient in half of the plots, 2016–2017 and 2018–2019), and two major hurricanes (Irma and María, September 2017). Woody seedlings and saplings were censused yearly from 2015 to 2019, with an additional census in 2015 after the drought ended. We evaluated disturbance-driven changes in species richness, diversity, and composition across ontogeny. We then used Bayesian predictive trait modeling to assess how species responded to disturbance and how this might influence the functional structure of the plant community. Our results show decreased seedling richness after hurricane disturbance, as well as increased sapling richness and diversity after warming. We found a shift in species composition through time for both seedlings and saplings, yet the individual effects of each disturbance were not significant. At both ontogenetic stages, we observed about twice as many species responding to experimental warming as those responding to drought and hurricanes. Predicted changes in functional structure point to disturbance-driven functional shifts toward a mixture of fast-growing and drought-tolerant species. Our findings demonstrate that the tropical forest understory community is more resistant to climatic stressors than expected, especially at the sapling stage. However, early signs of changes in species composition suggest that, in a warming climate with frequent droughts and hurricanes, plant communities might shift over time toward fast-growing or drought-tolerant species

Testing the Unification Model for AGN in the Infrared: are the obscuring tori of Type 1 and 2 Seyferts different?

We present new mid-infrared (MIR) imaging data for three Type-1 Seyfert galaxies obtained with T-ReCS on the Gemini-South Telescope at subarcsecond resolution. Our aim is to enlarge the sample studied in a previous work to compare the properties of Type-1 and Type-2 Seyfert tori using clumpy torus models and a Bayesian approach to fit the infrared nuclear spectral energy distributions (SEDs). Thus, the sample considered here comprises 7 Type-1, 11 Type-2, and 3 intermediate-type Seyferts. The unresolved IR emission of the Seyfert 1 galaxies can be reproduced by a combination of dust heated by the central engine and direct AGN emission, while for the Seyfert 2 nuclei only dust emission is considered. These dusty tori have physical sizes smaller than 6 pc radius, as derived from our fits. Unification schemes of AGN account for a variety of observational differences in terms of viewing geometry. However, we find evidence that strong unification may not hold, and that the immediate dusty surroundings of Type-1 and Type-2 Seyfert nuclei are intrinsically different. The Type-2 tori studied here are broader, have more clumps, and these clumps have lower optical depths than those of Type-1 tori. The larger the covering factor of the torus, the smaller the probability of having direct view of the AGN, and vice-versa. In our sample, Seyfert 2 tori have larger covering factors and smaller escape probabilities than those of Seyfert 1. All the previous differences are significant according to the Kullback-Leibler divergence. Thus, on the basis of the results presented here, the classification of a Seyfert galaxy as a Type-1 or Type-2 depends more on the intrinsic properties of the torus rather than on its mere inclination towards us, in contradiction with the simplest unification model.Comment: 21 pages, 14 figures, Appendix including supplementary figures. Accepted by Ap