10,330 research outputs found

    Different evolutionary pathways underlie the morphology of wrist bones in hominoids

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    BACKGROUND The hominoid wrist has been a focus of numerous morphological analyses that aim to better understand long-standing questions about the evolution of human and hominoid hand use. However, these same analyses also suggest various scenarios of complex and mosaic patterns of morphological evolution within the wrist and potentially multiple instances of homoplasy that would benefit from require formal analysis within a phylogenetic context.We identify morphological features that principally characterize primate - and, in particular, hominoid (apes, including humans) - wrist evolution and reveal the rate, process and evolutionary timing of patterns of morphological change on individual branches of the primate tree of life. Linear morphological variables of five wrist bones - the scaphoid, lunate, triquetrum, capitate and hamate - are analyzed in a diverse sample of extant hominoids (12 species, 332 specimens), Old World (8 species, 43 specimens) and New World (4 species, 26 specimens) monkeys, fossil Miocene apes (8 species, 20 specimens) and Plio-Pleistocene hominins (8 species, 18 specimens). RESULT Results reveal a combination of parallel and synapomorphic morphology within haplorrhines, and especially within hominoids, across individual wrist bones. Similar morphology of some wrist bones reflects locomotor behaviour shared between clades (scaphoid, triquetrum and capitate) while others (lunate and hamate) indicate clade-specific synapomorphic morphology. Overall, hominoids show increased variation in wrist bone morphology compared with other primate clades, supporting previous analyses, and demonstrate several occurrences of parallel evolution, particularly between orangutans and hylobatids, and among hominines (extant African apes, humans and fossil hominins). CONCLUSIONS Our analyses indicate that different evolutionary processes can underlie the evolution of a single anatomical unit (the wrist) to produce diversity in functional and morphological adaptations across individual wrist bones. These results exemplify a degree of evolutionary and functional independence across different wrist bones, the potential evolvability of skeletal morphology, and help to contextualize the postcranial mosaicism observed in the hominin fossil record

    Uso da ressonância magnética nuclear de baixo campo na determinação rápida do teor de umidade em madeiras.

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    Neste trabalho é apresentada uma recomendação da utilização da técnica de ressonância magnética nuclear (RMN) de baixo campo como método alternativo na determinação rápida da umidade em madeiras. Este método utiliza o espectrômetro de RMN desenvolvido pela Embrapa Instrumentação Agropecuária e transferido para a Empresa GIL Equipamentos Especiais.bitstream/CNPDIA/9437/1/RT12_99.pd

    Global aspects of gravitomagnetism

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    We consider global properties of gravitomagnetism by investigating the gravitomagnetic field of a rotating cosmic string. We show that although the gravitomagnetic field produced by such a configuration of matter vanishes locally, it can be detected globally. In this context we discuss the gravitational analogue of the Aharonov-Bohm effect.Comment: 10 pages - Typeset using REVTE

    Light clusters and the pasta phase

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    The effects of including light clusters in nuclear matter at low densities are investigated within four different parametrizations of relativistic models at finite temperature. Both homogeneous and inhomogeneous matter (pasta phase) are described for neutral nuclear matter with fixed proton fractions. We discuss the effect of the density dependence of the symmetry energy, the temperature and the proton fraction on the non-homogeneous matter forming the inner crust of proto-neutron stars. It is shown that the number of nucleons in the clusters, the cluster proton fraction and the sizes of the Wigner Seitz cell and of the cluster are very sensitive to the density dependence of the symmetry energy.Comment: 14 pages, 14 figures; Accepted for publication in Phys. Rev.

    Group Theory analysis of phonons in two-dimensional Transition Metal Dichalcogenides

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    Transition metal dichalcogenides (TMDCs) have emerged as a new two dimensional materials field since the monolayer and few-layer limits show different properties when compared to each other and to their respective bulk materials. For example, in some cases when the bulk material is exfoliated down to a monolayer, an indirect-to-direct band gap in the visible range is observed. The number of layers NN (NN even or odd) drives changes in space group symmetry that are reflected in the optical properties. The understanding of the space group symmetry as a function of the number of layers is therefore important for the correct interpretation of the experimental data. Here we present a thorough group theory study of the symmetry aspects relevant to optical and spectroscopic analysis, for the most common polytypes of TMDCs, i.e. 2Ha2Ha, 2Hc2Hc and 1T1T, as a function of the number of layers. Real space symmetries, the group of the wave vectors, the relevance of inversion symmetry, irreducible representations of the vibrational modes, optical selection rules and Raman tensors are discussed.Comment: 32 pages, 4 figure

    Development of a laboratorial robotized filament winding equipment

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    Filament winding is the mostly suitable technology to produce at large volume scale structural composite parts presenting revolution form, such as pressure and non-pressure vessels, tanks and pipes, aircraft fuselage, helicopter blades, etc. [1, 2]. Such process allows optimising the deposition and orientation of continuous reinforced fibres in order to manufacture the best performance and customised composite part for each specific application. Another advantage of this technological processing method is the possibility it gives of using almost all continuous reinforcing fibres (carbon, glass, aramid) and plastic matrices (both thermosetting and/or thermoplastic). As the investment for acquiring a filament winding equipment was too much high, the Pole for Innovation in Polymer Engineering (PIEP) decided to use its proper know-how to self-develop an own robotised filament winding equipment for laboratorial use. The aim of such equipment is to support R&D projects with industrial companies concerning the production of filament wound scaled prototype parts for testing, optimising and improving fibre deposition trajectories, study the complex shape manufacturing, testing the application of new fibres and matrices, etc. This paper will present the developed and built robotised filament winding equipment and will discuss its major possibilities, trajectories and software data acquisition capabilities and the results obtained on composite parts manufactured by it.FCT projeto SFRH/BD/60852/200

    Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation

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    We aim to investigate the effect of the escaping ionizing radiation on the color selection of high redshift galaxies and identify candidate Lyman continuum (LyC) emitters. The intergalactic medium prescription of Inoue et al.(2014) and galaxy synthesis models of Bruzual&Charlot (2003) have been used to properly treat the ultraviolet stellar emission, the stochasticity of the intergalactic transmission and mean free path in the ionizing regime. Color tracks are computed by turning on/off the escape fraction of ionizing radiation. At variance with recent studies, a careful treatment of IGM transmission leads to no significant effects on the high-redshift broad-band color selection. The decreasing mean free path of ionizing photons with increasing redshift further diminishes the contribution of the LyC to broad-band colors. We also demonstrate that prominent LyC sources can be selected under suitable conditions by calculating the probability of a null escaping ionizing radiation. The method is applied to a sample of galaxies extracted from the GOODS-S field. A known LyC source at z=3.795 is successfully recovered as a LyC emitter candidate and another convincing candidate at z=3.212 is reported. A detailed analysis of the two sources (including their variability and morphology) suggests a possible mixture of stellar and non-stellar (AGN) contribution in the ultraviolet. Conclusions: Classical broad-band color selection of 2.5<z<4.5 galaxies does not prevent the inclusion of LyC emitters in the selected samples. Large fesc in relatively bright galaxies (L>0.1L*) could be favored by the presence of a faint AGN not easily detected at any wavelength. A hybrid stellar and non-stellar (AGN) ionizing emission could coexist in these systems and explain the tensions found among the UV excess and the stellar population synthesis models reported in literature.Comment: Accepted for publication in Astronomy & Astrophysics. 13 pages, 7 figure
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