Chiral 3π\pi-exchange NN-potentials: Results for dominant next-to-leading order contributions

We calculate in (two-loop) chiral perturbation theory the local NN-potentials generated by the three-pion exchange diagrams with one insertion from the second order chiral effective pion-nucleon Lagrangian proportional to the low-energy constants $c_{1,2,3,4}$. The resulting isoscalar central potential vanishes identically. In most cases these $3\pi$-exchange potentials are larger than the ones generated by the diagrams involving only leading order vertices due to the large values of $c_{3,4}$ (which mainly represent virtual $\Delta$-excitation). A similar feature has been observed for the chiral $2\pi$-exchange. We also give suitable (double-integral) representations for the spin-spin and tensor potentials generated by the leading-order diagrams proportional to $g_A^6$ involving four nucleon propagators. In these cases the Cutkosky rule cannot be used to calculate the spectral-functions in the infinite nucleon mass limit since the corresponding mass-spectra start with a non-vanishing value at the $3\pi$-threshold. Altogether, one finds that chiral $3\pi$-exchange leads to small corrections in the region $r\geq 1.4$ fm where $1\pi$- and chiral $2\pi$-exchange alone provide a very good strong NN-force as shown in a recent analysis of the low-energy pp-scattering data-base.Comment: 11 pages, 7 figures, to be published in The Physical Review

Teor de nitrogênio em sementes de Araucaria angustifolia.

Edição dos resumos do 18º Congresso Brasileiro de Sementes, 2013, Florianópolis

Microbial populations and activities of mangrove, restinga and Atlantic forest soils from Cardoso Island, Brazil

AimMangroves provide a distinctive ecological environment that differentiates them from other ecosystems. This study deal to evaluate the frequency of microbial groups and the metabolic activities of bacteria and fungi isolated from mangrove, restinga and Atlantic forest soils.Methods and ResultsSoil samples were collected during the summer and winter at depths of 0-2, 2-5 and 5-10cm. Except for fungi, the counts of the total, sporulating, Gram-negative, actinomycetes, nitrifying and denitrifying bacteria decreased significantly in the following order: Atlantic forest>mangrove>restinga. The counts of micro-organisms decreased by 11 and 21% from the surface to the 2-5 and 5-10cm layers, but denitrifying bacteria increased by 44 and 166%, respectively. A larger growth of micro-organisms was verified in the summer compared with the winter, except for actinomycetes and fungi. The average frequency of bacteria isolated from mangrove, restinga and Atlantic forest soils was 95, 77 and 78%, and 93, 90 and 95% for fungi, respectively. Bacteria were amylolytic (33%), producers of acid phosphatase (79%) and solubilizers (18%) of inorganic phosphate. The proportions of fungi were 19, 90 and 27%.ConclusionThe mangrove soil studied had higher chemical characteristics than the Atlantic forest, but the high salinity may have restricted the growth of microbial populations.Significance and Impact of the StudyEstimates of the microbial counts and activities were important to elucidate the differences of mangrove ecosystem from restinga and Atlantic forest.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

The alien synanthropic Salticidae in Brazil (Araneae)

ABSTRACT Salticidae is the most diverse family of Araneae and in Brazil, there are 667 species. Among these species, five are synanthropic exotics: Plexippus paykulli (Audouin, 1826), Hasarius adansoni (Audouin, 1826), Menemerus bivittatus (Dufour, 1831), M. nigli Wesołowska & Freudenschuss, 2012 and Thyene coccineovittata (Simon, 1886). To understand the current distribution of these species in Brazil, seven collections of 643 lots were examined from seven Brazilian zoological collections. The synanthropic exotic species with the highest records were Plexippus paykulli, Menemerus bivittatus, and Hasarius adansoni, generally collected and associated with human dwellings and buildings. They are present in all regions (North, Northeast, Midwest, and South macro-regions), with the largest region, in all regions of the country in 22 states and 98 municipalities, followed by Hasarius adansoni in 17 states and 88 municipalities, Menemerus bivittatus in 19 states and 68 municipalities. Menemerus nigli and Thyene coccineovittata are from recent introductions that occurred in the city of Rio de Janeiro, Rio de Janeiro, Brazil

Data from: Long-term endemism of two highly divergent lineages of the amphibian-killing fungus in the Atlantic Forest of Brazil

The recent global spread of the amphibian-killing fungus [Batrachochytrium dendrobatidis (Bd)] has been closely tied to anthropogenic activities; however, regional patterns of spread are not completely understood. Using historical samples, we can test whether Bd was a spreading or endemic pathogen in a region within a particular time frame, because those two disease states provide different predictions for the regional demographic dynamics and population genetics of Bd. Testing historical patterns of pathogen prevalence and population genetics under these predictions is key to understanding the evolution and origin of Bd. Focusing on the Atlantic Forest (AF) of Brazil, we used qPCR assays to determine the presence or absence of Bd on 2799 preserved postmetamorphic anurans collected between 1894 and 2010 and used semi-nested PCRs to determine the frequency of rRNA ITS1 haplotypes from 52 samples. Our earliest date of detection was 1894. A mean prevalence of 23.9% over time and spatiotemporal patterns of Bd clusters indicate that Bd has been enzootic in the Brazilian AF with no evidence of regional spread within the last 116 years. ITS1 haplotypes confirm the long-term presence of two divergent strains of Bd (BdGPL and Bd-Brazil) and three spatiotemporally broad genetic demes within BdGPL, indicating that Bd was not introduced into southeast Brazil by the bullfrog trade. Our data show that the evolutionary history and pathogen dynamics of Bd in Brazil is better explained by the endemic pathogen hypothesis

Long-term endemism of two highly divergent lineages of the amphibian-killing fungus in the Atlantic Forest of Brazil

The recent global spread of the amphibian-killing fungus [Batrachochytrium dendrobatidis (Bd)] has been closely tied to anthropogenic activities; however, regional patterns of spread are not completely understood. Using historical samples, we can test whether Bd was a spreading or endemic pathogen in a region within a particular time frame, because those two disease states provide different predictions for the regional demographic dynamics and population genetics of Bd. Testing historical patterns of pathogen prevalence and population genetics under these predictions is key to understanding the evolution and origin of Bd. Focusing on the Atlantic Forest (AF) of Brazil, we used qPCR assays to determine the presence or absence of Bd on 2799 preserved postmetamorphic anurans collected between 1894 and 2010 and used semi-nested PCRs to determine the frequency of rRNA ITS1 haplotypes from 52 samples. Our earliest date of detection was 1894. A mean prevalence of 23.9% over time and spatiotemporal patterns of Bd clusters indicate that Bd has been enzootic in the Brazilian AF with no evidence of regional spread within the last 116years. ITS1 haplotypes confirm the long-term presence of two divergent strains of Bd (BdGPL and Bd-Brazil) and three spatiotemporally broad genetic demes within BdGPL, indicating that Bd was not introduced into southeast Brazil by the bullfrog trade. Our data show that the evolutionary history and pathogen dynamics of Bd in Brazil is better explained by the endemic pathogen hypothesis.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq