5,861 research outputs found

    The role of bacteria in pine wilt disease: insights from microbiome analysis.

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    Pine Wilt Disease (PWD) has a significant impact on Eurasia pine forests. The microbiome of the nematode (the primary cause of the disease), its insect vector, and the host tree may be relevant for the disease mechanism. The aim of this study was to characterize these microbiomes, from three PWD-affected areas in Portugal, using Denaturing Gradient Gel Electrophoresis, 16S rRNA gene pyrosequencing, and a functional inference-based approach (PICRUSt). The bacterial community structure of the nematode was significantly different from the infected trees but closely related to the insect vector, supporting the hypothesis that the nematode microbiome might be in part inherited from the insect. Sampling location influenced mostly the tree microbiome (P < 0.05). Genes related both with plant growth promotion and phytopathogenicity were predicted for the tree microbiome. Xenobiotic degradation functions were predicted in the nematode and insect microbiomes. Phytotoxin biosynthesis was also predicted for the nematode microbiome, supporting the theory of a direct contribution of the microbiome to tree-wilting. This is the first study that simultaneously characterized the nematode, tree and insect-vector microbiomes from the same affected areas, and overall the results support the hypothesis that the PWD microbiome plays an important role in the disease's development

    Apologues and fables as educational resources on earth sciences

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    Comunicação apresentada ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)O presente trabalho visa dar a conhecer a literatura infantil editada no âmbito do Programa de Divulgação no triénio dedicado ao Ano Internacional do Planeta Terra (AIPT), em Portugal (2007-2009), a que o Comité Português para o AIPT deu o seu apoio institucional – representada por apólogos e fábulas inovadores, cujos protagonistas e/ou enredos remetem para o conhecimento no âmbito de várias disciplinas das Ciências da Terra, entre outras –, bem como destacar o papel que tais narrativas podem desempenhar como recursos educativos pertinentes para a promoção de um desenvolvimento sustentável.This paper aims to promote children’s literature published in the framework of the Outreach Programme during the three years dedicated to the International Year of Planet Earth (IYPE), in Portugal (2007-2009), which the Portuguese Committee for IYPE gave its institutional support – represented by innovative apologues and fables, whose protagonists and/or plots refer to the knowledge of several disciplines within the Earth Sciences, among others - as well as highlighting the role that such narratives can play as educational resources relevant to the promotion of sustainable development

    Measurement of miniband parameters of a doped superlattice by photoluminescence in high magnetic fields

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    We have studied a 50/50\AA superlattice of GaAs/Al0.21_{0.21}Ga0.79_{0.79}As composition, modulation-doped with Si, to produce n=1.4×1012n=1.4\times 10^{12} cm2^{-2} electrons per superlattice period. The modulation-doping was tailored to avoid the formation of Tamm states, and photoluminescence due to interband transitions from extended superlattice states was detected. By studying the effects of a quantizing magnetic field on the superlattice photoluminescence, the miniband energy width, the reduced effective mass of the electron-hole pair, and the band gap renormalization could be deduced.Comment: minor typing errors (minus sign in eq. (5)

    Superlattice Magnetophonon Resonances in Strongly Coupled InAs/GaSb Superlattices

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    We report an experimental study of miniband magnetoconduction in semiconducting InAs/GaSb superlattices. For samples with miniband widths below the longitudinal optical phonon energy we identify a new superlattice magnetophonon resonance (SLMPR) caused by resonant scattering of electrons across the mini-Brillouin zone. This new resonant feature arises directly from the drift velocity characteristics of the superlattice dispersion and total magnetic quantisation of the superlattice Landau level minibands.Comment: 9 pages, 8 figures, submitted to Phys. Rev.

    Long-Term Visual Object Tracking Benchmark

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    We propose a new long video dataset (called Track Long and Prosper - TLP) and benchmark for single object tracking. The dataset consists of 50 HD videos from real world scenarios, encompassing a duration of over 400 minutes (676K frames), making it more than 20 folds larger in average duration per sequence and more than 8 folds larger in terms of total covered duration, as compared to existing generic datasets for visual tracking. The proposed dataset paves a way to suitably assess long term tracking performance and train better deep learning architectures (avoiding/reducing augmentation, which may not reflect real world behaviour). We benchmark the dataset on 17 state of the art trackers and rank them according to tracking accuracy and run time speeds. We further present thorough qualitative and quantitative evaluation highlighting the importance of long term aspect of tracking. Our most interesting observations are (a) existing short sequence benchmarks fail to bring out the inherent differences in tracking algorithms which widen up while tracking on long sequences and (b) the accuracy of trackers abruptly drops on challenging long sequences, suggesting the potential need of research efforts in the direction of long-term tracking.Comment: ACCV 2018 (Oral

    Interrelations between “Tales by Mrs. Earth” and the International Year of Planet Earth

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    Comunicação apresentada ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)No presente trabalho apresentam-se os “Contos da Dona Terra”, uma colectânea de dez narrativas destinadas ao público infantil, que incluem apólogos e fábulas, com conteúdos interrelacionáveis com as dez temáticas do Ano Internacional do Planeta Terra. Esta obra, editada também em Braille e Mirandês, visa ajudar a compreender a dinâmica da Terra, e apela à necessidade de respeitar o planeta e os seus recursos, como forma de alcançar um futuro mais sustentável.This work presents the "Tales by Mrs. Earth" a collection of ten stories aimed at children, including apologues and fables, with contents which may be related to the ten themes of the International Year of Planet Earth. Edited also in Braille and Mirandês, the book aims to help understand the dynamics of the Earth, and call for the need to respect the planet and its resources as a means of achieving a more sustainable future

    Meson-like Baryons and the Spin-Orbit Puzzle

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    I describe a special class of meson-like \Lambda_Q excited states and present evidence supporting the similarity of their spin-independent spectra to those of mesons. I then examine spin-dependent forces in these baryons, showing that predicted effects of spin-orbit forces are small for them for the same reason they are small for the analogous mesons: a fortuitous cancellation between large spin-orbit forces due to one-gluon-exchange and equally large inverted spin-orbit forces due to Thomas precession in the confining potential. In addition to eliminating the baryon spin-orbit puzzle in these states, this solution provides a new perspective on spin-orbit forces in all baryons.Comment: 24 pages, 4 figure

    Physicochemical characterization of biomaterials commonly used in dentistry as bone substitutes--comparison with human bone

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    The present work focuses on the physicochemical characterization of selected mineral-based biomaterials that are frequently used in dental applications. The selected materials are commercially available as granules from different biological origins: bovine, porcine, and coralline. Natural and calcined human bone were used for comparison purposes. Besides a classical rationalization of chemical composition and crystallinity, a major emphasis was placed on the measurement of various morphostructural properties such as particle size, porosity, density, and specific surface area. Such properties are crucial to acquiring a full interpretation of the in vivo performance. The studied samples exhibited distinct particle sizes (between 200 and 1000 microm) and shapes. Mercury intrusion revealed not only that the total sample porosity varied considerably (33% for OsteoBiol, 50% for PepGen P-15, and 60% for BioOss) but also that a significant percentage of that porosity corresponded to submicron pores. Biocoral was not analyzed by this technique as it possesses larger pores than those of the porosimeter upper limit. The density values determined for the calcined samples were close to the theoretical values of hydroxyapatite. However, the values for the collagenated samples were lower, in accordance with their lower mineral content. The specific surface areas ranged from less than 1 m(2)/g (Biocoral) up to 60 m(2)/g (BioOss). The chemical and phase composition of most of the samples, the exception being Biocoral (aragonite), were hydroxyapatite based. Nonetheless, the samples exhibited different organic material content as a consequence of the distinct heat treatments that each had received

    Octreotide for conservative management of postoperative chylothorax in the neonate

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    Chylothorax is a possible complication after thoracotomy. Treatment is initially conservative and includes drainage and correction of nutritional losses. Surgical treatment is reserved for cases not responsive to medical measures. The authors report on the clinical case of a premature neonate with a traumatic chylothorax secondary to esophageal atresia surgical correction. The use of octreotide allowed the resolution of the effusion without adverse effects and avoided the surgical treatment

    Cosmic microwave background and parametric resonance in reheating

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    The variation of the perturbative 3-curvature parameter, \zeta, is investigated in the period of reheating after inflation. The two-field model used has the inflaton, with an extra scalar field coupled to it, and non-linear effects of both fields are included as well as a slow decay mechanism into the hydrodynamic fluid of the radiation era. Changes in \zeta occur and persist into the succeeding cosmic eras to influence the generation of the cosmic microwave background fluctuations.Comment: 21 pages, 6 figures.Corrects misprinted formula and 2 number
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