1,201 research outputs found
An update on the physiology of two- and three-toed sloths
Physiological and pharmacological research undertaken on sloths during the past 30 years is comprehensively reviewed. This includes the numerous studies carried out upon the respiratory and cardiovascular systems, anesthesia, blood chemistry, neuromuscular responses, the brain and spinal cord, vision, sleeping and waking, water balance and kidney function and reproduction. Similarities and differences between the physiology of sloths and that of other mammals are discussed in detail
Some anisotropic universes in the presence of imperfect fluid coupling with spatial curvature
We consider Bianchi VI spacetime, which also can be reduced to Bianchi types
VI0-V-III-I. We initially consider the most general form of the energy-momentum
tensor which yields anisotropic stress and heat flow. We then derive an
energy-momentum tensor that couples with the spatial curvature in a way so as
to cancel out the terms that arise due to the spatial curvature in the
evolution equations of the Einstein field equations. We obtain exact solutions
for the universes indefinetly expanding with constant mean deceleration
parameter. The solutions are beriefly discussed for each Bianchi type. The
dynamics of the models and fluid are examined briefly, and the models that can
approach to isotropy are determined. We conclude that even if the observed
universe is almost isotropic, this does not necessarily imply the isotropy of
the fluid (e.g., dark energy) affecting the evolution of the universe within
the context of general relativity.Comment: 17 pages, no figures; to appear in International Journal of
Theoretical Physics; in this version (which is more concise) an equation
added, some references updated and adde
PU tensile tests: conventional and digital image correlation analysis
Polyurethane (PU) is a polymer, used as coating, paint, foam, adhesive, and even in biomedical devices. To furthermore expand its applications, it can be combined with additives such as Calcium Carbonate (CaCO3), an inexpensive material, widely available in nature, or with fibers, such as glass fibers explored in several sectors, likewise the aerospace and automobile industries. To determine the mechanical properties of these materials, the tensile test is the most used due to its great ease of application and flexibility. However, conventional processes, such as the use of strain gauges or crosshead displacement data, may not provide detailed information about the strain field, or cannot be able to evaluate the Poisson's ratio and the true stresses for the entire stressstrain curve. Thus, digital image correlation (DIC) methods are a promising alternative, consisting of strain field measurement without contact with the surface of the structure. In this context, this study carried out the tensile characterization of two main polyurethane samples: one petrochemical, distributed by Sika (R), reinforced with type E glass fiber: and the other, natural, manufactured by Kehl (R) from castor oils, and combined with CaCO3 particles. During the tests, DIC was applied to evaluate the Poisson's ratio and, subsequently, Scanning Electron Microscopy (SEM) analyses were performed, revealing a higher number of bubbles on Sika's polymer, which contributes to the reduction of the maximum supported stresses, since these pores, with dimensions of up to 25 hm, were regions where the cracks started and headed the breakage. Poisson's ratios were all around 0.4 and the highest tensile strength values were obtained from E-glass reinforced samples (TS015), around 117.24 +/- 13.20MPa. CaCO3 particles also acted as reinforced, increasing maximum stress reached from 20MPa to values between 29 and 37MPa.This research was partially funded through the base funding from the following research units: UIDB/00690/2020 (CIMO).info:eu-repo/semantics/publishedVersio
A legal framework for an elderly healthcare platform: A privacy and data protection overview
[EN] Cognitive problems are increasingly affecting the population, with the elderly being the ones most affected. This problem requires a new approach in terms of medical and social actions, personalisation, and services. The Ambient Assisted Living area provides solutions to allow elderly people to stay in their homes safely and with the appropriate care. The number of Ambient Assisted Living projects is increasing rapidly, leading to large commercial deployment, and most of these projects disregard the privacy and data protection of the users and the information that they process and save. The iGenda project is a Cognitive Assistant inserted in the Ambient Assisted Living area that provides help to users in their daily lives. However, since it requires the transfer of a large amount of private and personal data between the modules of the platform, fundamental rights may be at stake. This paper presents the iGenda platform, the principle rights of data protection and transmission, legal guarantees and latent ethical concerns. Furthermore, the dichotomy between current developments and legal and ethical aspects are explained. To overcome this problem, legal considerations and ethical considerations are presented, embracing appropriate solutions to features that present any threat. (C) 2017 Angelo Costa, Aliaksandra Yelshyna, Teresa C. Moreira, Francisco C.P. Andrade, Vicente Julian, Paulo Novais. Published by Elsevier Ltd. All rights reserved.This work has been supported by FCT - Fundacao para a Ciencia e Tecnologia within the Project Scope UID/CEC/00319/2013. A. Costa thanks the Fundacao para a Ciencia e a Tecnologia (FCT) Post-Doc scholarship with the Ref. SFRH/BPD/102696/2014. This work is also partially supported by the MINECO/FEDER TIN2012-36586-C03-01.Costa, A.; Yelshyna, A.; Moreira, TC.; Andrade, FC.; Julian Inglada, VJ.; Novais, P. (2017). A legal framework for an elderly healthcare platform: A privacy and data protection overview. Computer Law & Security Review. 33(5):647-658. https://doi.org/10.1016/j.clsr.2017.03.02164765833
Thermal conditions affecting heat transfer in FDM/FFE: a contribution towards the numerical modelling of the process
The performance of parts produced by Free Form Extrusion (FFE), an increasingly popular additive manufacturing technique, depends mainly on their dimensional accuracy, surface quality and mechanical performance. These attributes are strongly influenced by the evolution of the filament temperature and deformation during deposition and solidification. Consequently, the availability of adequate process modelling software would offer a powerful tool to support efficient process set-up and optimisation. This work examines the contribution to the overall heat transfer of various thermal phenomena developing during the manufacturing sequence, including convection and radiation with the environment, conduction with support and between adjacent filaments, radiation between adjacent filaments and convection with entrapped air. The magnitude of the mechanical deformation is also studied. Once this exercise is completed, it is possible to select the material properties, process variables and thermal phenomena that should be taken in for effective numerical modelling of FFE.This work was supported by Strategic Project - LA 25 - 2013–2014 [PEst-C/CTM/LA0025/2013]
A Step Forward in Breast Cancer Research: Gold Nanoparticles as Photothermal Therapy Enhancers
Gold nanoparticles (AuNPs) have been widely used and characterized for multiple biomedical applications, including the enhancement of photothermal therapy (PTT). AuNPs present a particular plasmon resonance band and are able to convert the absorbed optical radiation into heat, which validates their use in PTT. Several production methods have already been proposed for the synthesis of AuNPs, allowing to optimize the particles' morphology, size and optical properties. However, the production methods commonly used are frequently associated with the use of toxic reagents such as Cetyltrimethylammonium bromide, which presents some concerns for clinical applications. Herein, it is proposed a novel AuNPs' core synthesis method using tetrachloroauric acid and a mixture of reducing agents, later on coated with a combination of hyaluronic and oleic acids. The coating here represents a potential improvement of AuNPs biocompatibility, biodegradability and lifetime, while simultaneously potentiating the attachment towards specific ligands, such as the CD44 receptor, to develop more localized and highly selective tools. The produced functionalized nanoparticles were characterized by Dynamic Light Scattering, Microscopy Techniques and Spectroscopy, showing diameter sizes under 350 nm, polydispersity index smaller than 0.4 and enhanced absorbance in the Near Infrared (NIR, 650 to 900 nm) range. Moreover, the AuNPs safety and efficacy were preliminarily assessed in vitro using breast cancer cell lines. No toxicity was observed by MTT assay, both in breast cancer cell lines, and red blood cells. The irradiation process was proved to be safe; however, when combined with the AuNPs administration, it resulted in a significant reduction of cell viability for some of the breast cell lines tested. Thus, the results highlight the potential of the proposed system for some type of tumors, even though further tests are required to better understand the mechanisms behind the obtained results
A new heparan sulfate from the mollusk nodipecten nodosus inhibits merozoite invasion and disrupts rosetting and cytoadherence of plasmodium falciparum
Despite treatment with effective antimalarial drugs, the mortality rate is still high in severe cases of the disease, highlighting the need to find adjunct therapies that can inhibit the adhesion of Pf-iEs. In this context, we evaluated a new heparan sulfate (HS) from Nodipecten nodosus for antimalarial activity and inhibition of P. falciparum cytoadhesion and rosetting. Parasite inhibition was measured by SYBR green using a cytometer. HS was assessed in rosetting and cytoadhesion assays under static and flow conditions using CHO and HLEC cells expressing ICAM1 and CSA, respectively. This HS inhibited merozoite invasion similar to heparin. Moreover, mollusk HS decreased cytoadherence of P. falciparum to CSA (chondroitin sulfate A) and ICAM-1 (intercellular adhesion molecule-1) on the surface of endothelial cells under static and flow conditions. In addition, this glycan efficiently disrupted rosettes. These findings support a potential use for mollusk HS as adjunct therapy for severe malaria114CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPnão temnão tem2012/16525-2; 2017/18611-7; 2010/18571-6; 2015/20774-
Aplicação de Multiclassificadores Heterogêneos no Reconhecimento de Classes Estruturais de Proteínas
O reconhecimento de dobras de proteína é um dos principais problemas em aberto da biologia molecular e uma importante abordagem para a descoberta de estruturas de proteínas desconsiderando a similaridade de suas seqüências. Neste contexto, as ferramentas computacionais, principalmente as técnicas da Aprendizagem de Máquina (AM), tornaram-se alternativas essenciais para tratar esse problema, considerando o grande volume de dados empregado. Este trabalho apresenta os resultados obtidos com a aplicação de diferentes sistemas multiclassificadores heterogêneos (Stacking, StackingC e Vote), empregando tipos distintos de classificadores base (Árvores de Decisão, K-Vizinhos Mais próximos, Naive Bayes, Máquinas de Vetores Suporte e Redes Neurais), à tarefa de predição de classes estruturais de proteína
Transport Properties of Random Walks on Scale-Free/Regular-Lattice Hybrid Networks
We study numerically the mean access times for random walks on hybrid
disordered structures formed by embedding scale-free networks into regular
lattices, considering different transition rates for steps across lattice bonds
() and across network shortcuts (). For fast shortcuts () and
low shortcut densities, traversal time data collapse onto an universal curve,
while a crossover behavior that can be related to the percolation threshold of
the scale-free network component is identified at higher shortcut densities, in
analogy to similar observations reported recently in Newman-Watts small-world
networks. Furthermore, we observe that random walk traversal times are larger
for networks with a higher degree of inhomogeneity in their shortcut
distribution, and we discuss access time distributions as functions of the
initial and final node degrees. These findings are relevant, in particular,
when considering the optimization of existing information networks by the
addition of a small number of fast shortcut connections.Comment: 8 pages, 6 figures; expanded discussions, added figures and
references. To appear in J Stat Phy
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