982 research outputs found

    Mammals in Portugal: A data set of terrestrial, volant, and marine mammal occurrences in Portugal

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    Open Research: The complete data set is available as Supporting Information and are also available in Figshare at https://doi.org/10.6084/m9.figshare.14938437Mammals are threatened worldwide, with ca. 26% of all species being included in the IUCN threatened categories. This overall pattern is primarily associated to habitat loss or degradation, and human persecution for terrestrial mammals, and pollution, open net fishing, climate change and prey depletion for marine mammals. Mammals play a key role in maintaining ecosystems functionality and resilience, and therefore information on their distribution is crucial to delineate and support conservation actions. MAMMALS IN PORTUGAL is a publicly available data set compiling unpublished georeferenced occurrence records of 92 terrestrial, volant, and marine mammals in mainland Portugal and archipelagos of Azores and Madeira that includes 107,852 data entries between 1873 and 2021 (72% of the data occurring in 2000 and 2021). The methods used to collect the data were: live observations/captures (42%), sign surveys (38%), camera trapping (16%), bioacoustics surveys (4%) and radio-tracking and inquiries that represent less than 1% of the records. The data set includes 13 types of records: 1) burrows | soil mounds | tunnel, 2) capture, 3) colony, 4) dead animal | hair | skulls | jaws, 5) genetic confirmation, 6) inquiries, 7) observation of live animal, 8), observation in shelters, 9) photo trapping | video, 10), predators diet | pellets | pine cones/nuts, 11) scat | track | ditch, 12) telemetry and 13) vocalization | echolocation. The spatial uncertainty of most records ranges between 0 and 100 m (76%). Rodentia (n = 34,754) has the highest number of records followed by Chiroptera (n = 18,858), Carnivora (n = 18,594), Lagomorpha (n = 17,679), Cetartiodactyla (n = 11,568) and Eulipotyphla (n = 6,400). The data set includes records of species classified by the IUCN as threatened (e.g., Oryctolagus cuniculus (n = 12,407), Monachus monachus (n = 1512), and Lynx pardinus (n = 197)]. We believe that this data set may stimulate the publication of other European countries data sets which would certainly contribute to ecology and conservation-related research, and therefore assisting on the development of more accurate and tailored conservation management strategies for each species. There are no copyright restrictions; please cite this data paper when the data are used in publicationsinfo:eu-repo/semantics/acceptedVersio

    Uniform flow of viscoelastic fluids past a confined falling cylinder

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    Uniform steady flow of viscoelastic fluids past a cylinder placed between two moving parallel plates is investigated numerically with a finite-volume method. This configuration is equivalent to the steady settling of a cylinder in a viscoelastic fluid, and here, a 50% blockage ratio is considered. Five constitutive models are employed (UCM, Oldroyd-B, FENE-CR, PTT and Giesekus) to assess the effect of rheological properties on the flow kinematics and wake patterns. Simulations were carried out under creeping flow conditions, using very fine meshes, especially in the wake of the cylinder where large normal stresses are observed at high Deborah numbers. Some of the results are compared with numerical data from the literature, mainly in terms of a drag coefficient, and significant discrepancies are found, especially for the constant-viscosity constitutive models. Accurate solutions could be obtained up to maximum Deborah numbers clearly in excess of those reported in the literature, especially with the PTT and FENECR models. The existence or not of a negative wake is identified for each set of model parameters

    An improved k-ε turbulence model for FENE-P fluids capable to reach high drag reduction regime

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    An improved k-ε turbulence model for viscoelastic fluids is developed to predict turbulent flows in complex geometries, with polymeric solutions described by the finitely extensible nonlinear elastic-Peterlin constitutive model. The k-ε model is tested against a wide range of direct numerical simulation data, with different rheological parameters combinations, and is capable to capture the drag reduction for all regimes of low, intermediate and high, with good performance. Two main contributions are proposed, one through the viscoelastic closures present in the turbulent kinetic energy and dissipation equations, and the other, by modifying eddy viscosity model damping function to incorporate the viscoelastic effect close to the wall, especially at the buffer layer. In addition, improvements have been made to the cross-correlations between the fluctuating components of the polymer conformation and rate of strain tensors present in the Reynolds-averaged transport equation for the conformation tensor. The main advantage is the capacity to predict all components of the tensor with good performance.indisponível

    MAMMALS IN PORTUGAL: A data set of terrestrial, volant, and marine mammal occurrences in Portugal

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    Mammals are threatened worldwide, with ca. 26% of all species being included in the IUCN threatened categories. This overall pattern is primarily associated to habitat loss or degradation, and human persecution for terrestrial mammals, and pollution, open net fishing, climate change and prey depletion for marine mammals. Mammals play a key role in maintaining ecosystems functionality and resilience, and therefore information on their distribution is crucial to delineate and support conservation actions. MAMMALS IN PORTUGAL is a publicly available data set compiling unpublished geo-referenced occurrence records of 92 terrestrial, volant, and marine mammals in mainland Portugal and archipelagos of Azores and Madeira that includes 107,852 data entries between 1873 and 2021 (72% of the data occurring in 2000 and 2021). The methods used to collect the data were: live observations/captures (42%), sign surveys (38%), camera trapping (16%), bioacoustics surveys (4%) and radio-tracking and inquiries that represent less than 1% of the records. The data set includes 13 types of records: 1) burrows | soil mounds | tunnel, 2) capture, 3) colony, 4) dead animal | hair | skulls | jaws, 5) genetic confirmation, 6) inquiries, 7) observation of live animal, 8), observation in shelters, 9) photo trapping | video, 10), predators diet | pellets | pine cones/nuts, 11) scat | track | ditch, 12) telemetry and 13) vocalization | echolocation. The spatial uncertainty of most records ranges between 0 and 100 m (76%). Rodentia (n = 34,754) has the highest number of records followed by Chiroptera (n = 18,858), Carnivora (n = 18,594), Lagomorpha (n = 17,679), Cetartiodactyla (n = 11,568) and Eulipotyphla (n = 6400). The data set includes records of species classified by the IUCN as threatened (e.g., Oryctolagus cuniculus (n = 12,407), Monachus monachus (n = 1512), and Lynx pardinus (n = 197)]. We believe that this data set may stimulate the publication of other European countries data sets which would certainly contribute to ecology and conservation-related research, and therefore assisting on the development of more accurate and tailored conservation management strategies for each species. There are no copyright restrictions; please cite this data paper when the data are used in publications

    Semi-analytical solutions for the poiseuille-couette flow of a generalised Phan-Thien-Tanner fluid

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    This work presents new analytical and semi-analytical solutions for the pure Couette and Poiseuille-Couette flows, described by the recently proposed (Ferras et al., A Generalised Phan-Thien-Tanner Model, JNNFM 2019) viscoelastic model, known as the generalised Phan-Thien-Tanner constitutive equation. This generalised version considers the Mittag-Leffler function instead of the classical linear or exponential functions of the trace of the stress tensor, and provides one or two new fitting constants in order to achieve additional fitting flexibility. The analytical solutions derived in this work allow a better understanding of the model, and therefore contribute to improve the modelling of complex materials, and will provide an interesting challenge to computational rheologists, to benchmarking and to code verification.This research was funded by FEDER through COMPETE2020-Programa Operacional Competitividade e Internacionalizacao (POCI) and by national funds through FCT-Fundacao para a Ciencia e a Tecnologia, I. P. through Projects PTDC/EMS-ENE/3362/2014, POCI-01-0145-FEDER-016665, UID-MAT-00013/2013, and UID/MAT/00297/2013 as well as grant number SFRH/BPD/100353/2014. This work was partially supported by the Fundacao para a Ciencia e a Tecnologia (Portuguese Foundation for Science and Technology) through the project UID/MAT/00297/2019 (Centro de Matematica e Aplicacoes)

    Hydrodynamic entrance length for laminar flow in microchannels with rectangular cross section

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    This work presents a detailed numerical investigation on the required development length (L=L/B) in laminar Newtonian fluid flow in microchannels with rectangular cross section and different aspect ratios (AR). The advent of new microfluidic technologies shifted the practical Reynolds numbers (Re) to the range of unitary (and even lower) orders of magnitude, i.e., creeping flow conditions. Therefore, accurate estimations of L at Re≤O(1) are important for microsystem design. At such low Reynolds numbers, in which inertial forces are less dominant than viscous forces, flow characteristics become necessarily different from those at the macroscale where Re is typically much larger. A judicious choice of mesh refinement and adequate numerical methods allowed obtaining accurate results and a general correlation for estimating L, valid in the ranges 0≤Re≤2000 and 0.1≤AR≤1, thus covering applications in both macro and microfluidics.The authors acknowledge the support by CEFT (Centro de Estudos de Fenómenos de Transporte) and Project PTDC/EMS-ENE/3362/2014—POCI-01-0145-FEDER-016665, funded by FEDER funds through COMPETE2020 “Programa Operacional Competitividade e Internacionaliza” (POCI) and by national funds through FCT “Fundac ao para a Ciência e a Tecnologia”, I.P. L.L. Ferrás would also like to thank FCT for financial support through scholarship SFRH/BPD/100353/2014 and projects UIDB/00013/2020 and UIDP/00013/2020. A. Sucena, A. M. Afonso, M. M. Alves and F. T. Pinho are also grateful to FCT for funding through projects UIDB/00532/2020 and UIDP/00532/2020. A. Sucena thanks FCT for the Ph.D. Grant SFRH/BD/115547/201

    Numerical Simulation of the Production of Core-Shell Microparticles

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    Conventional methods that are commonly used for the preparation of microbubble delivery systems include sonication, high-shear emulsification, and membrane emulsification. However, these methods present significant disadvantages, namely, poor control over the particle size and distribution. To date, engineering core-shell microparticles remains a challenging task. Thus, there is a demand for new techniques that can enable control over the size, composition, stability, and uniformity of microparticles. Microfluidic techniques offer great advantages in the fabrication of microparticles over the conventional processes because they require mild and inert processing conditions. In this work, we present a numerical study based on the finite volume method, for the development of capsules by considering the rheological properties of three phases, air, a perfluorohexane (C6 F14) and a polymeric solution constituted of a solution of 0.25% w/v alginate. This methodology allows studying the stability and behavior of microparticles under different processing conditions

    Recent Advances in Complex Fluids Modeling

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    In this chapter, we present a brief description of existing viscoelastic models, starting with the classical differential and integral models, and then focusing our attention on new models that take advantage of the enhanced properties of the Mittag-Leffler function (a generalization of the exponential function). The generalized models considered in this work are the fractional Kaye-Bernstein, Kearsley, Zapas (K-BKZ) integral model and the differential generalized exponential Phan-Thien and Tanner (PTT) model recently proposed by our research group. The integral model makes use of the relaxation function obtained from a step-strain applied to the fractional Maxwell model, and the differential model generalizes the familiar exponential Phan-Thien and Tanner constitutive equation by substituting the exponential function of the trace of the stress tensor by the Mittag-Leffler function. Since the differential model is based on local operators, it reduces the computational time needed to predict the flow behavior, and, it also allows a simpler description of complex fluids. Therefore, we explore the rheometric properties of this model and its ability (or limitations) in describing complex flows

    A viscoelastic two-phase solver using a phase-field approach

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    In this work we discuss the implementation and the performance of an in-house viscoelastic two-phase solver, based on a diffuse interface approach. The Phase-Field method is considered and the Cahn-Hilliard equation is employed for describing the transport of a binary fluid system. The interface between the two fluids utilises a continuum approach, which is responsible for smoothing the inherent discontinuities of sharp interface models, facilitating studies that are related to morphological changes of the interface, such as droplet breakup and coalescence. The two-phase solver manages to predict the expected dynamics for all the cases investigated, and exhibits an overall good performance. The numerical implementation is able to predict the expected physical response of the oscillating drop case, while the performance is also validated by examining the droplet deformation case. The corresponding history of the deformation is predicted for several systems considering Newtonian fluids, viscoelastic fluids and combinations of both. Finally, we demonstrate the ability of the solver to capture the complex interfacial patterns of the Rayleigh-Taylor instability for different Atwood numbers when Newtonian fluids are considered. In the two regimes identified, the system is modified to consider viscoelastic fluids and the influence of elasticity is investigated

    S100B inhibition protects from chronic experimental autoimmune encephalomyelitis

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    © The Author(s) 2022. Published by Oxford University Press on behalf of the Guarantors of Brain. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.Studies have correlated excessive S100B, a small inflammatory molecule, with demyelination and associated inflammatory processes occurring in multiple sclerosis. The relevance of S100B in multiple sclerosis pathology brought an emerging curiosity highlighting its use as a potential therapeutic target to reduce damage during the multiple sclerosis course, namely during inflammatory relapses. We examined the relevance of S100B and further investigated the potential of S100B-neutralizing small-molecule pentamidine in chronic experimental autoimmune encephalomyelitis. S100B depletion had beneficial pathological outcomes and based on promising results of a variety of S100B blockade strategies in an ex vivo demyelinating model, we choose pentamidine to assay its role in the in vivo experimental autoimmune encephalomyelitis. We report that pentamidine prevents more aggressive clinical symptoms and improves recovery of chronic experimental autoimmune encephalomyelitis. Blockade of S100B by pentamidine protects against oligodendrogenesis impairment and neuroinflammation by reducing astrocyte reactivity and microglia pro-inflammatory phenotype. Pentamidine also increased regulatory T cell density in the spinal cord suggesting an additional immunomodulatory action. These results showed the relevance of S100B as a main driver of neuroinflammation in experimental autoimmune encephalomyelitis and identified an uncharacterized mode of action of pentamidine, strengthening the possibility to use this drug as an anti-inflammatory and remyelinating therapy for progressive multiple sclerosis.This work was funded by grants from Ordem dos Farmacêuticos (AF), Merck KGaA (AF) and Fundação de Ciênciase Tecnologia (UIDB/04138/2020; UIDP/04138/2020) (iMed.ULisboa).info:eu-repo/semantics/publishedVersio
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