The Influence of Temperature on the Behavior of Burrowing in Larvae of the Blowflies, Chrysomya albiceps and Lucilia cuprina, Under Controlled Conditions

Blowflies use discrete, ephemeral substrates for larval development. After exhaustion of the food supply, larvae will disperse in search of sites to burrow and pupate or will seek other sources of food in a process known as post-feeding larval dispersal. In this study, the effect of temperature was investigated as it is one of the most important aspects of the environmental variables in this process. 800 larvae of the blowflies Chrysomya albiceps (Wiedemann 1819) and Lucilia cuprina (Wiedemann 1830) (Diptera: Calliphoridae) were incubated in tubes covered with vermiculite at 15, 20, 25 and 30°C. For each pupa, the body weight, sex and depth of burrowing were determined. Statistical tests were used to examine the relationship of depth of burrowing and body weight to the temperature at which burrowing occurred. Depth of burrowing was affected differently by temperature for both of the species studied; L. cuprina larvae burrowed deeper at lower and higher temperatures while C. albiceps larvae burrowed less at extreme temperatures. Additionally, temperature had a significant effect on the body weight of L. cuprina larvae as body weight decreased as temperature increased, whereas for C. albiceps, pupal weight increased up to 25°C and then decreased abruptly at a higher temperatures. The maximum body weight was also differently affected in the two species; in L. cuprina, the maximal weight was at 15°C and for C. albiceps weight was maximal at 20°C

Homogeneous polynomial vector fields of degree 2 on the 2-dimensional sphere

Let X be a homogeneous polynomial vector field of degree 2 on S2 having finitely many invariant circles. Then, we prove that each invariant circle is a great circle of S2, and at most there are two invariant circles. We characterize the global phase portrait of these vector fields. Moreover, we show that if X has at least an invariant circle then it does not have limit cycles

Testing circumstellar disk lifetimes in young embedded clusters associated with the Vela Molecular Ridge

Context. The Vela Molecular Ridge hosts a number of young embedded star clusters in the same evolutionary stage. Aims. The main aim of the present work is testing whether the fraction of members with a circumstellar disk in a sample of clusters in the cloud D of the Vela Molecular Ridge, is consistent with relations derived for larger samples of star clusters with an age spread. Besides, we want to constrain the age of the young embedded star clusters associated with cloud D. Methods. We carried out L (3.78 microns) photometry on images of six young embedded star clusters associated with cloud D of the Vela Molecular Ridge, taken with ISAAC at the VLT. These data are complemented with the available HKs photometry. The 6 clusters are roughly of the same size and appear to be in the same evolutionary stage. The fraction of stars with a circumstellar disk was measured in each cluster by counting the fraction of sources displaying a NIR excess in colour-colour (HKsL) diagrams. Results. The L photometry allowed us to identify the NIR counterparts of the IRAS sources associated with the clusters. The fraction of stars with a circumstellar disk appears to be constant within errors for the 6 clusters. There is a hint that this is lower for the most massive stars. The age of the clusters is constrained to ~1-2 Myr. Conclusions. The fraction of stars with a circumstellar disk in the observed sample is consistent with the relations derived from larger samples of star clusters and with other age estimates for cloud D. The fraction may be lower for the most massive stars. Our results agree with a scenario where all intermediate and low-mass stars form with a disk, whose lifetime is shorter for higher mass stars.Comment: 13 pages, 11 figures, accepted for publication in Astronomy and Astrophysic

Synchronization by dynamical relaying in electronic circuit arrays

We experimentally study the synchronization of two chaotic electronic circuits whose dynamics is relayed by a third parameter-matched circuit, to which they are coupled bidirectionally in a linear chain configuration. In a wide range of operating parameters, this setup leads to synchronization between the outer circuits, while the relaying element remains unsynchronized. The specifics of the synchronization differ with the coupling level: for low couplings a state of intermittent synchronization between the outer circuits coexists with one of antiphase synchronization. Synchronization becomes in phase for moderate couplings, and for strong coupling identical synchronization is observed between the outer elements, which are themselves synchronized in a generalized way with the relaying element. In the latter situation, the middle element displays a triple scroll attractor that is not possible to obtain when the chaotic oscillator is isolated.Comment: 7 pages, 12 figure

"Let them dream of life eternal, we shall live it" : George R. R. Martin's fevre dream, slavery and vampires in the United States of America

Fevre Dream é um romance de horror histórico publicado por George R.R. Martin em 1982. Apesar de ser frequentemente ignorado pelo estudos acadêmicos da obra de Martin, trata-se de um romance importante não apenas porque é nele que o autor definitivamente abraça a darkfantasy, mas também porque nele o vampirismo é usado como instrumento de forte crítica social. Este artigo analisa como o sistema escravagista é descrito em Fevre Dream em associação com memórias de escravidão e o vampirismo, e vem estruturado em quatro seções que enfocam, respectivamente, as memórias de escravidão produzidas nos EUA depois do século XIX; Abner Marsh, o protagonista; a dicotomia entre as forças vampíricas opostas representadas por Joshua York e Damon Julian; e o status dos personagens negros no romance.Fevre Dream is a historical horror novel published by George R.R. Martin in 1982. Despite being frequently overlooked by scholarship on Martin’s oeuvre, it is an important novel not only because in it the author definitely embraces dark fantasy, but also because it uses vampirism as a tool for strong social criticism. This article describes how the slavery system is depicted in Fevre Dream in association with memories of slavery and vampirism, and it is structured in four sections: slavery memories produced in the United States after the 19th century; Abner Marsh, the protagonist; the dichotomy between the opposite vampiric forces repsented by Joshua York and Damon Julian; and the status of the black characters in the novel

Spectroscopic Studies and Characterization of a Novel Electron-Transfer Chain

A novel two-component enzyme system from Escherichia coli involving a flavorubredoxin (FlRd) and its reductase was studied in terms of spectroscopic, redox, and biochemical properties of its constituents. FlRd contains one FMN and one rubredoxin (Rd) center per monomer. To assess the role of the Rd domain, FlRd and a truncated form lacking the Rd domain (FlRd¢Rd), were characterized. FlRd contains 2.9 ( 0.5 iron atoms/subunit, whereas FlRd¢Rd contains 2.1 ( 0.6 iron atoms/subunit. While for FlRd one iron atom corresponds to the Rd center, the other two irons, also present in FlRd¢Rd, are most probably due to a di-iron site. Redox titrations of FlRd using EPR and visible spectroscopies allowed us to determine that the Rd site has a reduction potential of -140 ( 15 mV, whereas the FMN undergoes reduction via a red-semiquinone, at -140 ( 15 mV (Flox/Flsq) and -180 ( 15 mV (Flsq/Flred), at pH 7.6. The Rd site has the lowest potential ever reported for a Rd center, which may be correlated with specific amino acid substitutions close to both cysteine clusters. The gene adjacent to that encoding FlRd was found to code for an FAD-containing protein, (flavo)rubredoxin reductase (FlRd-reductase), which is capable of mediating electron transfer from NADH to DesulfoVibrio gigas Rd as well as to E. coli FlRd. Furthermore, electron donation was found to proceed through the Rd domain of FlRd as the Rd-truncated protein does not react with FlRd-reductase. In vitro, this pathway links NADH oxidation with dioxygen reduction. The possible function of this chain is discussed considering the presence of FlRd homologues in all known genomes of anaerobes and facultative aerobes

PRODUÇÃO DE CASTANHA-DO-BRASIL CERTIFICADA NA RESEX CHICO MENDES: IMPACTOS E AVALIAÇÕES

O processo de ocupação econômica da Amazônia tem produzido sérios problemas sociais, econômicos e ambientais. As comunidades florestais estão cada vez mais marginalizadas, mesmo aquelas que moram em áreas de conservação, notadamente nas Reservas Extrativistas (RESEX). O ponto nevrálgico para o desenvolvimento sustentável está no nível de desempenho econômico da produção de origem florestal sustentável, face aos sistemas convencionais de exploração, visto que os atributos intangíveis das explorações sustentáveis, tais como a manutenção do equilíbrio ecológico, não são capturados pelo mercado. A certificação ambiental florestal surge como um mecanismo que pode capturar, em termos monetários, os fluxos econômicos das funções ambientais da floresta, auxiliando no sustento das famílias e da conservação do meio ambiente florestal. Busca-se, no presente trabalho, avaliar os impactos da certificação ambiental da castanha-do-Brasil, produzida na RESEX Chico Mendes. De acordo com os resultados encontrados, por intermédio da utilização de medidas de resultado econômico e de eficiência econômica, constata-se que a certificação ambiental em comunidades florestais gera preços justos apropriados pelos produtores florestais, auxiliando na manutenção das famílias no interior da floresta.----------------------------------------------The process of economic occupation of the Amazon has produced serious social problems, economic and environmental. The forest communities are increasingly marginalized, even those who live in areas of conservation, especially in the Extractive Reserves (RESEX). The core point for sustainable development is at the level of economic performance of the production of sustainable forest origin, compared with the conventional systems of exploitation, since the intangible attributes of sustainable exploration, such as the maintenance of ecological balance, are not captured by the market. The environmental certification forest emerges as a mechanism that can capture, in monetary terms, the flow of economic environmental functions of forests, helping in the sustenance of families and the conservation of the environment forest. Search is, in this work, assess the impacts of environmental certification of Brazil-Nut, produced in RESEX Chico Mendes. According to the results found, through the use of economic measures to result in economic efficiency, it is clear that the environmental certification on forest communities generates fair prices for producers appropriate forest, assisting in the maintenance of families inside the forest.Certificação Ambiental, Reserva Extrativista, Amazônia, Avaliação Econômica, Environmental Certification, Extractive Reserve (RESEX), Amazon region, Economic Assessment, Resource /Energy Economics and Policy,