Environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range

Abstract Riascos, J. M., Heilmayer, O., Oliva, M. E., and Laudien, J. 2011. Environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range. – ICES Journal of Marine Science, 68: 823–833. Mesodesma donacium is a commercially important bivalve in Chile and Peru. During strong El Niño events, populations at the northern end of its geographic distribution are wiped out, so to understand its threshold responses to biotic and abiotic factors, the population dynamics of one of the northernmost population remnants was analysed between 2005 and 2007. Strong interannual differences were found in abundance, body mass, growth rate, somatic production, and the prevalence of the parasite Polydora bioccipitalis. A Spearman rank correlation analysis showed that changes in beach slope, seemingly linked to repeated storm surges, negatively affected the clam's abundance and seemingly also affected growth, mortality, body mass somatic production, and parasite prevalence. Infestation by P. bioccipitalis was restricted to adult clams. Juvenile clams suffered high mortality because they inhabit the intertidal zone, where wave action is strong. Larger clams also showed high mortality, which seemed best explained by a synergistic effect of parasite load and environmental stress. This parasite-climate-driven mortality of larger clams had a strong impact on somatic production and implied a dramatic loss of fecundity (82%), which may significantly affect the ability of the species to recover its former abundance and distribution.</jats:p

Long-Range Navigation on Complex Networks using L\'evy Random Walks

We introduce a strategy of navigation in undirected networks, including regular, random, and complex networks, that is inspired by L\'evy random walks, generalizing previous navigation rules. We obtained exact expressions for the stationary probability distribution, the occupation probability, the mean first passage time, and the average time to reach a node on the network. We found that the long-range navigation using the L\'evy random walk strategy, compared with the normal random walk strategy, is more efficient at reducing the time to cover the network. The dynamical effect of using the L\'evy walk strategy is to transform a large-world network into a small world. Our exact results provide a general framework that connects two important fields: L\'evy navigation strategies and dynamics on complex networks.Comment: 6 pages, 3 figure

Variación latitudinal del ciclo reproductivo de dos bivalvos con orígenes biogeográficos contrastantes a lo largo del ecosistema de afloramiento de la Corriente de Humboldt

Argopecten purpuratus (Lamarck, 1819) and Mesodesma donacium (Lamarck, 1818) are bivalves that inhabit the Humboldt Current Upwelling Ecosystem. They have contrasting biogeographical origins, suggesting that their responses to exogenous factors should differ. Using circular statistics, we examine synchrony/asynchrony in the reproductive cycle between populations of each species. The results indicate that there is reproductive asynchrony in both species along their distributional range. However, there was synchrony for A. purpuratus in several location-pairs, including Paita-Chimbote, Chimbote-Callao, Callao-Pisco and Pisco-Antofagasta. For M. donacium, there were only two synchronic groups: Camaná-Capellanía-Mehuín and Hornitos-Peñuelas-Longotoma-La Ligua-Cucao-Quilanlar. A. purpuratus showed gametogenenic activity throughout the year. In contrast, M. donacium showed strong seasonality, with gametogenesis in winter and spawning in spring/summer. In conclusion, the patterns observed for these sympatric species suggest that on a large scale the reproductive cycles follow the expected patterns for the contrasting biogeographic origin of each species, so it could be argued that they are modulated by endogenous factors. However, at a local scale, the reproductive cycles of these species show variation, likely determined by local oceanographic or hydrographic processes.Argopecten purpuratus (Lamarck, 1819) y Mesodesma donacium (Lamarck, 1818) son moluscos bivalvos endémicos del sistema de afloramiento de la Corriente de Humboldt pero tienen orígenes biogeográficos opuestos. Por tanto, se esperaría que los factores exógenos afectaran sus ritmos biológicos diferencialmente, entre ellos sus ciclos reproductivos. Mediante análisis de distribución circular se evaluó el sincronismo/asincronismo en ciclos reproductivos entre poblaciones de cada especie. Los resultados indican que existe asincronía reproductiva en ambas especies a lo largo de su distribución. Sin embargo para A. purpuratus se encontró varios pares de localidades sincrónicas: Paita-Chimbote; Chimbote-Callao; Callao-Pisco y Pisco-Antofagasta, y para M. donacium se dieron dos grupos sincrónicos, el primero entre las poblaciones de Camaná, Capellanía y Mehuín; y el segundo grupo entre Hornitos, Peñuelas, Longotoma, La Ligua, Cucao y Quilanlar. A. purpuratus presentó actividad gametogénica continua. En contraste, M. donacium presentó una marcada estacionalidad, con gametogénesis durante invierno y desoves durante primavera y/o verano. En conclusión, los patrones observados para ambas especies simpátricas sugieren que, a gran escala el ciclo reproductivo sigue los patrones esperados para el origen biogeográfico contrastante de cada especie, por lo tanto se podría argumentar que es modulada por factores endógenos. Sin embargo, a escala local el ciclo reproductivo de ambas especies muestra variaciones, aparentemente influenciados por los factores oceanográficos o hidrográficos locales

Explaining Africa’s public consumption procyclicality : revisiting old evidence

This paper compiles a novel dataset of time-varying measures of government consumption cyclicality for a panel of 46 African economies between 1960 and 2014. Government consumption has, generally, been highly procyclical over time in this group of countries. However, sample averages hide serious heterogeneity across countries with the majority of them showing procyclical behavior despite some positive signs of graduation from the “procyclicality trap” in a few cases. By means of weighted least squares regressions, we find that more developed African economies tend to have a smaller degree of government consumption procyclicality. Countries with higher social fragmentation and those are more reliant on foreign aid inflows tend to have a more procyclical government consumption policy. Better governance promotes counter- cyclical fiscal policy whileincreased democracy dampens it. Finally, some fiscal rules are important in curbing the procyclical behavior of government consumption.info:eu-repo/semantics/publishedVersio

Cirurgia periodontal exploratória

Abstract. In clinical practice, there are numerous cases in which it is difficult to establish an accurate diagnosis and determine the correct therapeutic conduct to be followed, despite diagnostic aids, radiographic images and clinical examinations. The main purpose of exploratory surgery is to arrive at a live definitive diagnosis, with the possibility of detecting changes in the tissues and determining the degree of undetectable involvement; it has the added value of immediately providing available therapeutic options for resolving the problem, which makes it the only “method” with the potential to become an effective procedure.En la práctica clínica, existen numerosos casos en los que se dificulta establecer un diagnóstico certero y determinar la conducta terapéutica correcta a seguir, a pesar de las ayudas diagnósticas, las imágenes radiográficas y el examen clínico. La cirugía exploratoria se define como “el procedimiento manual operatorio destinado a evidenciar el origen de un problema que no ha podido ser determinado por otros medios”. Su principal propósito es llegar a un diagnóstico definitivo en vivo y en directo, con la posibilidad de detectar alteraciones en los tejidos y de determinar el grado de compromiso no detectable; con el valor agregado de aportar inmediatamente las vías terapéuticas disponibles para solucionar el problema, lo cual la convierte en el único “método” con potencial de transformarse en un procedimiento eficaz.Na prática clínica, existem numerosos casos nos que se dificulta estabelecer um diagnóstico preciso e determinar a conduta terapêutica correta a seguir, apesar das ajudas diagnósticas, as imagens radiográficas e o exame clínico. O principal propósito da cirurgia exploratória é chegar a um diagnóstico definitivo ao vivo e a cores, com a possibilidade de detectar alterações nos tecidos e de determinar o grau de compromisso não detectável; com o valor agregado de contribuir imediatamente para as vias terapêuticas disponíveis para solucionar o problema, o que a converte no único “método” com potencial de transformar-se em um procedimento eficaz

Snakebites mapping in municipalities of the Coffee Triangle Region in Colombia using Geographic Information Systems (GIS)

Objective: We sought to develop epidemiological maps using geographical information systems (GIS) for the incidence of reported venomous snakebites in the Coffee-Triangle region of Colombia, between 2007 and 2011. Methods: Surveillance cases data (2007-2011) were used to estimate annual incidence rates of snakebites (cases/100,000 pop) to develop the first maps in the 53 municipalities of this region (departments Caldas, Quindío, Risaralda). The GIS software used was Kosmo Desktop 3.0RC1®. Thirty thematic maps were developed according to municipalities and years. Results: A total of 617 cases were reported (56.08% from Caldas, 32.58% from Risaralda and 11.35% from Quindío), for a cumulated regional rate of 25. 25 cases/100,000 pop (35.43 for Caldas, 21.86 for Risaralda and 12.81% for Quindío). The highest cumulated rate was reported in the less developed and more rural municipality of one department (Pueblo Rico, Risaralda) with 265.64 cases/100,000 pop. Between 2007 and 2011, a considerable increase was seen in the rates. At Pueblo Rico, Risaralda, there was a change from 41.04 cases/100,000pop in 2007 up to 63.11 cases/100,000pop in 2011 (1.54 times higher). From Caldas, Samaná showed a high variation from 19.47 to 77.7 (3.99 times higher). Conclusions: Morbidity of snakebites is highly concentrated in one department (Caldas). Use of GIS-based epidemiological maps allows guiding decisions-taking for prevention and control of public health problems that still represents a significant issue in the region and the country, such as snakebites

Snakebites mapping in municipalities of the Coffee Triangle Region in Colombia using Geographic Information Systems (GIS)

Objective: We sought to develop epidemiological maps using geographical information systems (GIS) for the incidence of reported venomous snakebites in the Coffee-Triangle region of Colombia, between 2007 and 2011. Methods: Surveillance cases data (2007-2011) were used to estimate annual incidence rates of snakebites (cases/100,000 pop) to develop the first maps in the 53 municipalities of this region (departments Caldas, Quindío, Risaralda). The GIS software used was Kosmo Desktop 3.0RC1®. Thirty thematic maps were developed according to municipalities and years. Results: A total of 617 cases were reported (56.08% from Caldas, 32.58% from Risaralda and 11.35% from Quindío), for a cumulated regional rate of 25. 25 cases/100,000 pop (35.43 for Caldas, 21.86 for Risaralda and 12.81% for Quindío). The highest cumulated rate was reported in the less developed and more rural municipality of one department (Pueblo Rico, Risaralda) with 265.64 cases/100,000 pop. Between 2007 and 2011, a considerable increase was seen in the rates. At Pueblo Rico, Risaralda, there was a change from 41.04 cases/100,000pop in 2007 up to 63.11 cases/100,000pop in 2011 (1.54 times higher). From Caldas, Samaná showed a high variation from 19.47 to 77.7 (3.99 times higher). Conclusions: Morbidity of snakebites is highly concentrated in one department (Caldas). Use of GIS-based epidemiological maps allows guiding decisions-taking for prevention and control of public health problems that still represents a significant issue in the region and the country, such as snakebites