844 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
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
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
Qualidade pós-colheita de frutos de mangueira ("Mangifera indica" L.) var. 'Tommy Atkins' sob sistema orgânico no submédio São Francisco (Brasil)
O objetivo do trabalho foi avaliar a qualidade pós -
colheita de frutos de mangueira Tommy Atkins, cultivada sob
sistema orgânico. Os frutos foram avaliados logo ao
chegarem ao laboratório (0) e após armazenamento em
câmara fria a 10,5º ± 1 ºC e 85,5º ± 5 % de UR, durante, 14,
28 e 42 dias após a colheita (DAC), sendo que após cada
período, foram retirados da câmara fria e mantidos durante
quatro dias a 21 ± 1º C e 55-65 % de UR, após o que foram
caracterizados física, biológica e químicamente. O
delineamento experimental foi em blocos inteiramente ao
acaso. As médias foram comparadas pelo teste de Tukey.
Os frutos foram avaliados quanto a: perda de água e a
aparência, danos mecânicos, coloração da casca, firmeza
da polpa, ocorrência de colapso interno, escurecimento de
lenticelas, danos por lesões devido ao ataque de
Lasiodiplodia, Colletotrichum ou por Alternaria ou por tripes;
SST, ATT e o pH da polpa. As mangas estavam aptas para
o consumo por volta dos 18 DAC, tempo, mais do que
suficiente para se proceder ao transporte do produto até
mercados distantes, como o americano e o europeu
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
Cardiovascular abnormalities in patients with oral cleft: a clinical-electrocardiographic-echocardiographic study
OBJECTIVES: The present study aims to describe the clinical, electrocardiographic, and echocardiographic cardiological findings in a group of patients with oral clefts. METHODS: This is a prospective cross-sectional study on 70 children (age range from 13 days to 19 years) with oral clefts who attended the multidisciplinary program of a university hospital from March 2013 to September 2014. The patients were evaluated by a pediatric cardiologist and underwent detailed anamnesis, physical examination, electrocardiogram, and echocardiogram. RESULTS: Sixty percent of the patients were male; 55.7% presented with cleft lip and palate, and 40.0% presented with health complaints. Comorbidities were found in 44.3%. Relevant pregnancy, neonatal, family and personal antecedents were present in 55.7%, 27.1%, 67.2%, and 24.3% of the patients, respectively. Regarding the antecedents, 15.2% of the patients presented with a cardiac murmur, 49.0% with a familial risk of developing plurimetabolic syndrome, and 6% with family antecedents of rheumatic fever. Electrocardiographic evaluation showed one case of atrioventricular block. Echocardiograms were abnormal in 35.7% of the exams, including 5 cases of mitral valve prolapse — one of which was diagnosed with rheumatic heart disease. CONCLUSION: The finding of a family risk of developing plurimetabolic syndrome and a diagnosis of rheumatic heart disease indicates that patients with oral clefts may be more prone to developing acquired heart disease. Thus, our findings highlight the importance of anamnesis and methodological triangulation (clinical-electrocardiographic-echocardiographic) in the investigation of patients with oral clefts and emphasize that cardiological follow-up to evaluate acquired and/or rhythm heart diseases is necessary. This strategy permits comorbidity prevention and individualized planned treatment
Cosmic Microwave Background Anisotropies from Scaling Seeds: Global Defect Models
We investigate the global texture model of structure formation in cosmogonies
with non-zero cosmological constant for different values of the Hubble
parameter. We find that the absence of significant acoustic peaks and little
power on large scales are robust predictions of these models. However, from a
careful comparison with data we conclude that at present we cannot safely
reject the model on the grounds of present CMB data. Exclusion by means of
galaxy correlation data requires assumptions on biasing and statistics. New,
very stringent constraints come from peculiar velocities.
Investigating the large-N limit, we argue that our main conclusions apply to
all global O(N) models of structure formation.Comment: LaTeX file with RevTex, 27 pages, 23 eps figs., submitted to Phys.
Rev. D. A version with higher quality images can be found at
http://mykonos.unige.ch/~kunz/download/lam.tar.gz for the LaTeX archive and
at http://mykonos.unige.ch/~kunz/download/lam.ps.gz for the compiled
PostScript fil
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