A retarded coupling approach to intermolecular interactions

A wide range of physical phenomena such as optical binding and resonance energy transfer involve electronic coupling between adjacent molecules. A quantum electrodynamical description of these intermolecular interactions reveals the presence of retardation effects. The clarity of the procedure associated with the construction of the quantum amplitudes and the precision of the ensuing results for observable energies and rates are widely acknowledged. However, the length and complexity of the derivations involved in such quantum electrodynamical descriptions increase rapidly with the order of the process under study. Whether through the use of time-ordering approaches, or the more expedient state-sequence method, time-consuming calculations cannot usually be bypassed. A simple and succinct method is now presented, which provides for a direct and still entirely rigorous determination of the quantum electrodynamical amplitudes for processes of arbitrarily high order. Using the approach, new results for optical binding in two- and three-particle systems are secured and discussed

La respuesta de la comunidad epilítica intermareal natural e impactada por las aguas residuales del Atlántico SO a pulsos (antes/después del verano) y descargas crónicas de aguas residuales en el período 1997 - 2014

Until 2014 Mar del Plata city discharged its untreated sewage effluents to the intertidal sector. This city has a marked seasonality in the urban discharge, varying between 2.8 and 3.5 m3.sec.-1 of effluents before/after summer. The effect on the intertidal benthic community was evaluated in both spatially, in sewage-impacted and reference sites, and temporarily in both the short term, before/after summer, and in long term along nine periods between 1997 - 2014. The bivalve Brachidontes rodriguezii, the ecosystem engineer, reach the maximum dominance and frequency in reference areas. Spatially the presence of opportunistic and tolerant species characterized the impacted areas, while in reference sites sensitive species were prevalent. The opportunistic polychaete species Capitella "capitata" sp. and Alitta succinea were dominant near the sewage discharge in firsts periods. In other periods the indicator species were Rhynchospio glutaea or Boccardia spp. From 2008 the invader Boccardia proboscidea characterized the sewage-impacted sites building massive reefs. The crustaceans Jassa falcata and Caprella sp. were very abundant at intermediate distances from the sewage discharge, while Monocorophium insidiosum was very abundant in sewage-impacted areas. The tolerant and opportunistic species are favored after the summer due to the extra organic matter input. All community parameters showed lower values after the summer, and also a trend to diminish along the studied period.Hasta el año 2014 la ciudad de Mar del Plata descargaba sus efluentes cloacales sin tratamiento al sector intermareal. Esta ciudad tiene una marcada estacionalidad en sus descargas, variando el caudal entre 2,8 a 3,5 m3.seg-1 antes/después del verano. El efecto sobre la comunidad bentónica intermareal fue evaluado en la escala espacial, en sitios de referencia y sitios impactados, y también temporalmente en el corto período de tiempo, antes/después del verano, y a lo largo de nueve períodos entre 1997 - 2014. El bivalvo Brachidontes rodriguezii, el ingeniero ecosistémico, alcanza su máxima dominancia y frecuencia en áreas de referencia. Espacialmente la presencia de especies oportunistas y tolerantes caracterizó los sitios impactados, mientras que en sitios de referencia las especies sensibles son prevalentes. En los primeros períodos el poliqueto oportunista Capitella “capitata” sp. fue dominante cerca de la descarga cloacal, y también Alitta succinea. En periodos posteriores las especies indicadoreas fueron Rhynchospio glutaea o Boccardia spp. Desde 2008 el poliqueto invasor Boccardia proboscidea caracterizó los sitios impactados por la descarga por masivos arrecifes. Los crustáceos Jassa falcata y Caprella sp. fueron muy abundantes a distancias intermedias de la descarga, mientras que Monocorophium insidiosum fue muy abundante en el àrea impactada por la descarga cloacal. Las especies tolerantes u oportunistas se vieron favorecidas después del verano debido al aporte extra de materia orgánica. Todos los parámetros comunitarios mostraron valores menores después del verano, y también se observa una tendencia a disminuir a lo largo de los períodos estudiados

EQUILIBRIUM MOISTURE CONTENT OF PARCHMENT ARABICA COFFEE

EQUILIBRIUM MOISTURE CONTENT OF PARCHMENT ARABICA COFFE

Large tectonic earthquakes induce sharp temporary decreases in seismic velocity in Volcán de Colima, Mexico

International audienceWe used the ambient noise cross-correlation and stretching methods to calculate variations in seismic velocities in the region of Volcán de Colima, Mexico. More than 15 years of continuous records were processed, producing long time series of velocity variations related to volcanic activity, meteorological effects, and earthquakes. Velocity variations associated with eruptive activity are tenuous, which probably reflects the open state of the volcano during the study period. Fifteen events among 26 regional tectonic earthquakes produced sharp, temporary decreases in seismic velocities, which then recovered progressively following a linear trend as a function of the logarithm of time. For the 15 events, the amplitude of the perturbation increased almost linearly with the logarithm of the amplitude of the seismic waves that shook the edifice. The most dramatic apparent velocity variation was a drop of up to 2.6% during the nearby M7.4 Tecomán earthquake in 2003. In order to locate the perturbation in the horizontal plane we applied an inverse method based on the radiative transfer approximation. We also used an original approach based on the frequency dependence of velocity variations to estimate the depth of the perturbation. Our results show that the velocity variation was well localized in the shallow layers (< 800 m) of the volcano, with almost no variations occurring outside the edifice. We discuss several possible interpretations and conclude that the most plausible explanation for the velocity decreases is the nonlinear elastic behavior of the granular volcanic material and its mechanical softening induced by transient strains

Metodologia do teste de imunofluorescência indireta para o diagnóstico da tripanosomose eqüina.

A tripanosomose causada pelo Trypanosoma evansi tem uma distribuição geográfica extremamente ampla. Ela ocorre no norte da África, Índia, Malásia, Indonésia, China, Rússia, Filipinas, América Central e América do Sul. O T. evansi causa a tripanosomose equina também conhecida no nordeste da Argentina e Pantanal como "mal de cadeiras". O T. evansi infecta uma ampla variedade de mamíferos e no Pantanal ele tem sido encontrado em cavalos, quoatis (Nasua nasua), cães, capivaras (Hydrochaeris hydrochaeris) e pequenos roedores (Oryzomys sp.). No Pantanal tripanosomose eqüina causa centenas de mortes todo ano. Esta publicação tem como objetivo descrever a metodologia do TIFI utilizada no Laboratório de Sanidade Animal da Embrapa Pantanal.bitstream/item/37539/1/CT39.pd

Métodos de diagnósticos parasitológicos das tripanosomoses bovinas e eqüinas.

As hemoparasitoses constituem enfermidades amplamente distribuídas em toda a América Latina e Caribe causando efeitos negativos na saúde dos rebanhos animais e principalmente sobre a produção e rentabilidade dos sistemas de produção animal estabelecidos nas diferentes regiões do continente (Tamasaukas, 2000). Dentre os hemopar·sitos que causam importantes enfermidades nos animais domésticos e silvestres na América do Sul, destacam-se os Trypanosoma evansi e T. vivax. No Pantanal o T. evansi causa tripanosomose eqüina também conhecida como "mal de cadeira". É uma das doenças causadas por protozoários mais importantes do Pantanal. O objetivo deste trabalho foi descrever os métodos parasitológicos utilizados no Laboratório de Sanidade Animal da Embrapa Pantanal.bitstream/item/37534/1/CT41.pd

Metodologia da criopreservação dos Trypanosomas evansi e Trypanosoma vivax.

Várias espécies do gênero Trypanosoma causam doenças parasitárias de considerável importância médica e veterinária em todas as partes da África, Ásia e as Américas. Estes parasitas exibem considerável diversidade genética intraespecífica, variação que tem complicado sua classificação taxonômica. Esta diversidade e variação podem ser definidas em ambos níveis: do genoma e genes individuais. Em razão desta diversidade genética tem se discutido muito sobre a representatividade das cepas mantidas em laboratório quando comparadas com os isolados de campo (Deane et al., 1984). Aparentemente existe uma adaptação do parasita na troca de hospedeiro. Sabe-se que um isolado de campo pode estar constituído por uma população heterogênea de tripanosomas. Nos estudos realizados pelo Laboratório de Sanidade Animal da Embrapa Pantanal foram encontradas variações na infectividade das cepas de T. evansi. Estas foram pouco infectivas em animais de laboratório quando recém isoladas do hospedeiro natural, apresentando um período prepatente de 12 a 43 dias e baixa parasitemia. Após algumas passagens, elas se mostraram mais infectivas com um período prepatente de 2 a 4 dias e uma parasitemia mais alta. Também foram observadas variações biométricas deste parasita nas passagens. Verificou-se que este parasita sofreu alterações morfométricas durante as passagens como provável conseqüência da adaptação ao novo hospedeiro ou seleção de algumas subpopulações. As características biométricas das passagens foram sempre maiores que as do isolado primário (Dávila et al., 1998). As amostras de campo diferiram significativamente dos isolados após várias passagens em animais de laboratório, sendo que quanto maior o número de passagens mais acentuação das diferenças morfológicas. A criopreservação pode contribuir para que sejam mantidas amostras com variabilidade genética original da cepa. Esse trabalho tem por objetivo descrever o método de criopreservação utilizado no Laboratório de Sanidade Animal da Embrapa Pantanal.bitstream/item/37530/1/CT40.pd

Influence of the state of light on the optically induced interparticle interaction

A general expression for the energy of interparticle interaction induced by an arbitrary mode of light is determined using quantum electrodynamics, and it is shown that the Casimir-Polder potential is included within this quantum result. Equations are also derived for the corresponding coupling induced by multimode number states of light, and the dependence of the pair energy on the Poynting vector and polarization state is determined. Attention is then focused on the interactions between particles trapped in counterpropagating coherent beams, both with and without interference, and it is shown that the results afford insights into the multiparticle structures that can be optically fabricated with counterpropagating input. Brief consideration is also given to the effect of squeezing the optical coherent state. Extending previous studies of optical binding in Laguerre-Gaussian beams, results are given for the case of particles trapped at radially different locations within the beam structure. Finally, consideration is given to interparticle interactions induced by broadband light, and it is shown how the length of optically fabricated particle chains can be controlled by the use of wavelength filters

Cryptic diversity and deep divergence in an upper Amazonian leaflitter frog, Eleutherodactylus ockendeni

Supplementary files available: Additional file 1: Specimen information. Museum catalogue numbers (QCAZ) for E. ockendeni and two outgroup species, GenBank accession numbers for cyt b and/or 16S fragment, and locality of origin for each individual used in the study.- Additional file 2: TN-corrected p-distance among cyt b haplotypes. TN-corrected p-distances among cyt b haplotypes of E. ockendeni, grouped by clade.[Background] The forests of the upper Amazon basin harbour some of the world's highest anuran species richness, but to date we have only the sparsest understanding of the distribution of genetic diversity within and among species in this region. To quantify region-wide genealogical patterns and to test for the presence of deep intraspecific divergences that have been documented in some other neotropical anurans, we developed a molecular phylogeny of the wide-spread terrestrial leaflitter frog Eleutherodactylus ockendeni (Leptodactylidae) from 13 localities throughout its range in Ecuador using data from two mitochondrial genes (16S and cyt b; 1246 base pairs). We examined the relation between divergence of mtDNA and the nuclear genome, as sampled by five speciesspecific microsatellite loci, to evaluate indirectly whether lineages are reproductively isolated where they co-occur. Our extensive phylogeographic survey thus assesses the spatial distribution of E. ockendeni genetic diversity across eastern Ecuador.[Results] We identified three distinct and well-supported clades within the Ecuadorean range of E. ockendeni: an uplands clade spanning north to south, a northeastern and central lowlands clade, and a central and southeastern clade, which is basal. Clades are separated by 12% to 15% net corrected p-distance for cytochrome b, with comparatively low sequence divergence within clades. Clades marginally overlap in some geographic areas (e.g., Napo River basin) but are reproductively isolated, evidenced by diagnostic differences in microsatellite PCR amplification profiles or DNA repeat number and coalescent analyses (in MDIV) best modelled without migration. Using Bayesian (BEAST) and net phylogenetic estimates, the Southeastern Clade diverged from the Upland/ Lowland clades in the mid-Miocene or late Oligocene. Lowland and Upland clades speciated more recently, in the early or late Miocene.[Conclusion] Our findings uncover previously unsuspected cryptic species diversity within the common leaflitter frog E. ockendeni, with at least three different species in Ecuador. While these clades are clearly geographically circumscribed, they do not coincide with any existing landscape barriers. Divergences are ancient, from the Miocene, before the most dramatic mountain building in the Ecuadorean Andes. Therefore, this diversity is not a product of Pleistocene refuges. Our research coupled with other studies suggests that species richness in the upper Amazon is drastically underestimated by current inventories based on morphospecies.Peer reviewe

Las Ericáceas en la Web: "Neotropical blueberries; the Plant Family Ericaceae"

Las plantas de la familia Ericaceae con distribución Neotropical cuentan con un portal de Internet llamado Neotropical Blueberries: The Plant Family Ericaceae (http://www.nybg.org/bsci/res/lut2/). La página Web está bajo el mantenimiento del Dr. James L. Luteyn del Jardín Botánico de Nueva York. La mayor parte de la informacióncontenida en este sitio se tomó de diversas investigaciones (en campo, herbario, biblioteca y laboratorio) realizadas por el Dr. Luteyn desde el año de 1975, como investigador del Jardín Botánico de Nueva York