No abstract

No abstract

No abstract

No abstract

Recently, the Directed Search Method has been proposed as a point-wise iterative search procedure that allows to steer the search, in any direction given in objective space, of a multi-objective optimization problem. While the original version requires the objectives' gradients, we consider here a possible modification that allows to realize the method without gradient information. This makes the novel algorithm in particular interesting for hybridization with set oriented search procedures, such as multi-objective evolutionary algorithms. In this paper, we propose the DDS, a gradient free Directed Search method, and make a first attempt to demonstrate its benefit, as a local search procedure within a memetic strategy, by integrating the DDS into the well-known algorithm MOEA/D. Numerical results on some benchmark models indicate the advantage of the resulting hybrid.

The Atacama region, Chile, presents one of the highest levels of mining exploitation of the country, which leads to high levels of contamination from mine tailings and other related environmental liabilities. One of the most complex situations occurred in the Chañaral city, north of Chile, where for over 50 years mine tailings were dumped on the coast, causing severe damage in the ecosystem. To evaluate the effects on terrestrial biota, we analyzed the concentration of cadmium and lead in tissues of Turkey Vulture (Cathartes aura). The results indicate that accumulation of cadmium in kidney was 10.31 μg/g (SD 8.00, range 0.27 to 20.73 μg/g) while in the liver was 5.24 μg/g (SD 8.00, range 0.49 to 19.70). There values are very high when compared to data for other birds with similar ecological role. In relation to the lead, concentration in liver was 0.86 μg/g (SD 2.03, range 0.15 -7.90), while in kidney was 1.05 μg/g (DS 2.54, range 0.044 to 9.86), values considered within the normal range. It is interesting to analyze from the perspective of the availability of these metals in the mining tailings, where lead (1.57 to 21.2 μg/g) presented higher levels than cadmium (0.061 to 1.085 μg/g). The difference between organs may be related to the role of metallothionein. We discuss the role of Turkey Vulture as a bioindicator of environmental liabilities. KEYWORDS:Ecotoxicology, Heavy Metals, Cathartes aura. RESUMENLa Región de Atacama, Chile, presenta uno de los mayores niveles de explotación minera del país, el cual a su vez genera altos niveles de contaminación por relaves mineros y otros pasivos ambientales relacionados. Una de las más complejas situaciones ocurrió en la ciudad de Chañaral, norte de Chile, donde fueron liberados relaves mineros a sus costas por sobre 50 años, causando graves daños en el ecosistema. Para evaluar los efectos en la biota terrestre, nosotros analizamos la concentración de Cadmio y Plomo en tejidos del Jote de Cabeza Colorada (Cathartes aura). Los resultados indican que la acumulación de Cadmio en el Riñón fue 10,31 μg/g (DS 8,00, rango 0,27 a 20,73 μg/g) mientras en el Hígado fue 5,24 μg/g (DS 8,00, rango 0,49 a 19,70). Estos valores son muy altos si se compara con datos de otras aves de similar rol ecológico. En relación al Plomo, la concentración en Hígado fue de 0,86 μg/g (DS 2,03, rango 0,15 a 7,90), mientras que en Riñón fue de 1,05 μg/g (DS 2,54, rango 0,044 a 9,86), valores considerados dentro del rango normal. Estos resultados son interesantes de analizar desde la perspectiva de la disponibilidad de estos metales en el relave minero, donde el Plomo (1,57 a 21,2 μg/g) presentó mayores niveles que el Cadmio (0,061 a 1,085 μg/g). La diferencia entre órganos puede ser relacionado al rol de las metalotioneinas. Discutimos el rol del Jote de Cabeza Colorada como bioindicador de contaminaciones ambientales.

Effects of climate change on reproductive number of Chagas diseaseBackground: Reproductive number (R 0 )-maps estimate risk zones of vector-borne diseases and geographical distribution changes under climate change. Aim: To map R 0 aiming to estimate the epidemiological risk of Chagas disease in Chile, its distribution and possible changes due to the global climate change. Material and Methods: We used a relationship between R 0 and entomological parameters of vectors as function of environmental variables, to map the risk of Chagas disease in Chile, under current and projected future environmental conditions. Results: We obtained a geographical R 0 estimation of Chagas disease in Chile. The highest R 0 averages correspond to the Central-Northern regions of Chile. T. cruzi transmission area could increase in the future due to climate changes.Independent of the future condition, both for optimistic and pessimistic climate change scenarios, the area of potential risk for Chagas disease transmission would increase. The estimated R 0 values suggest that, if a control of T. infestans is not maintained, Chagas disease endemic status will persist or increase, independently of the climate change scenarios. Conclusions: Mapping R 0 values is an effective method to assess the risk of Chagas disease. The eventual increase in the transmission area of the disease is worrisome. (Rev Med Chile 2019; 147: 683-692)

Age and sex structure of Andean Condor (Vultur gryphus) in feeding areas of central Chile. – The age and sex structures of the Andean Condor are known for some parts of its range while in other such areas data are lacking. The aim of this study was to obtain demographic data from the Andes of central Chile and to compare them with those available from other areas of distribution. From 2009–2010, we studied the age and sex structure of the Andean Condor in central Chile at feeding sites. Four carrion points were provided by us. The carrion comprised carcasses of sheep, donkey, and guanaco. Condor abundance at experimental carrion (mean = 36.25, SE = 48.45) was highly variable (CV = 134%), and we observed a higher proportion of adults (54%) than immatures (46%). Overall the sex ratio of adults was male-biased (52:48). The age and sex structures in our study are consistent with those found in other areas of the species’ distribution. Our results show a higher proportion of adult birds and males at feeding sites in the Andes of central Chile, which has implications on the population viability of the Andean Condor.