652 research outputs found
How we move is universal: scaling in the average shape of human activity
Human motor activity is constrained by the rhythmicity of the 24 hours
circadian cycle, including the usual 12-15 hours sleep-wake cycle. However,
activity fluctuations also appear over a wide range of temporal scales, from
days to a few seconds, resulting from the concatenation of a myriad of
individual smaller motor events. Furthermore, individuals present different
propensity to wakefulness and thus to motor activity throughout the circadian
cycle. Are activity fluctuations across temporal scales intrinsically
different, or is there a universal description encompassing them? Is this
description also universal across individuals, considering the aforementioned
variability? Here we establish the presence of universality in motor activity
fluctuations based on the empirical study of a month of continuous wristwatch
accelerometer recordings. We study the scaling of average fluctuations across
temporal scales and determine a universal law characterized by critical
exponents , and . Results are highly reminiscent of the
universality described for the average shape of avalanches in systems
exhibiting crackling noise. Beyond its theoretical relevance, the present
results can be important for developing objective markers of healthy as well as
pathological human motor behavior.Comment: Communicated to the Granada Seminar, "Physics Meets the Social
Sciences: Emergent cooperative phenomena, from bacterial to human group
behavior". June 14-19, 2015. La Herradura, Spai
Caracterização e gênese de perfis plínticos desenvolvidos de arenito do Grupo Bauru: II - mineralogia.
Nas paisagens do norte e oeste do estado de São Paulo, plintita e petroplintita constituem feições que se repetem com freqüência sobre os arenitos cretácicos da Formação Adamantina (Grupo Bauru). Com o objetivo de avaliar as características mineralógicas desses materiais e estudar sua gênese, selecionaram-se dois perfis de solos representativos da paisagem local e constituídos por feições plínticas, petroplínticas e mosqueados. O estudo foi realizado na baixa meia encosta de uma vertente situada na Estação Experimental de Agronomia de Pindorama, do Instituto Agronômico (IAC), região norte do estado de São Paulo. Com base nas observações em microscópio de varredura e microanálise pontual realizadas em glébulas selecionadas, bem como nas análises mineralógicas da fração argila desferrificada e dos óxidos de ferro de todos os horizontes dos perfis estudados, constatou-se que caulinita, hematita e goethita são os principais constituintes da fração argila dos nódulos e horizontes estudados. Os minerais mica, gibbsita e anatásio complementam a mineralogia da fração argila das glébulas, assemelhando-se em constituição ao material interglebular e aos demais horizontes dos perfis. Quartzo, feldspatos potássicos, traços de feldspatos sódicos e ilmenita foram identificados como componentes da fração silte e areia dos nódulos. A presença constante de minerais alteráveis nas glébulas petroplínticas é evidência de que a gênese desses materiais está relacionada com a ferruginização do saprolito. Este fato, associado aos baixos teores de Al na estrutura dos óxidos de ferro das glébulas, evidencia sua formação em condições hidromórficas, supostamente relacionadas com a solubilização e mobilização do ferro ferroso, lixiviado da paisagem a montante e reprecipitado na zona de vadosa, onde os maiores potenciais de oxidação favoreceram a segregação e a precipitação do ferro
Recovery and Fatigue Behavior of Forearm Muscles during a Repetitive Power Grip Gesture in Racing Motorcycle Riders
Despite a reduction in the maximal voluntary isometric contraction (MVCisom) observed systematically in intermittent fatigue protocols (IFP), decrements of the median frequency, assessed by surface electromyography (sEMG), has not been consistently verified. This study aimed to determine whether recovery periods of 60 s were too long to induce a reduction in the normalized median frequency (MFEMG) of the flexor digitorum superficialis and carpi radialis muscles. Twenty-one road racing motorcycle riders performed an IFP that simulated the posture and braking gesture on a motorcycle. The MVCisom was reduced by 53% (p < 0.001). A positive and significant relationship (p < 0.005) was found between MFEMG and duration of the fatiguing task when 5 s contractions at 30% MVCisom were interspersed by 5 s recovery in both muscles. In contrast, no relationship was found (p > 0.133) when 10 s contractions at 50% MVC were interspersed by 1 min recovery. Comparative analysis of variance (ANOVA) confirmed a decrement of MFEMG in the IFP at 30% MVCisom including short recovery periods with a duty cycle of 100% (5 s/5 s = 1), whereas no differences were observed in the IFP at 50% MVCisom and longer recovery periods, with a duty cycle of 16%. These findings show that recovery periods during IFP are more relevant than the intensity of MVCisom. Thus, we recommend the use of short recovery periods between 5 and 10 s after submaximal muscle contractions for specific forearm muscle training and testing purposes in motorcycle riders.</jats:p
Radiative corrections to the polarizability tensor of an electrically small anisotropic dielectric particle
Radiative corrections to the polarizability tensor of isotropic particles are fundamental to understand the energy balance between absorption and scattering processes. Equivalent radiative corrections for anisotropic particles are not well known. Assuming that the polarization within the particle is uniform, we derived a closed-form expression for the polarizability tensor which includes radiative corrections. In the absence of absorption, this expression of the polarizability tensor is consistent with the optical theorem. An analogous result for infinitely long cylinders was also derived. Magneto optical Kerr effects in non-absorbing nanoparticles with magneto-optical activity arise as a consequence of radiative corrections to the electrostatic polarizability tensor.This work has been supported by the EU NMP3-SL-2008-214107-Nanomagma, the Spanish MICINN Consolider NanoLight (CSD2007-00046), FIS2006-11170-C02-02 and by the Comunidad
de Madrid Microseres-CM Program. R.G.-M. acknowledges support from the EU COST-MP0803. Work by R.G.-M. and L.S.F.-P. was supported by the MICINN “Juan de la Cierva” Program.Peer reviewe
Bootstrapping Conditional GANs for Video Game Level Generation
Generative Adversarial Networks (GANs) have shown im-pressive results for
image generation. However, GANs facechallenges in generating contents with
certain types of con-straints, such as game levels. Specifically, it is
difficult togenerate levels that have aesthetic appeal and are playable atthe
same time. Additionally, because training data usually islimited, it is
challenging to generate unique levels with cur-rent GANs. In this paper, we
propose a new GAN architec-ture namedConditional Embedding Self-Attention
Genera-tive Adversarial Network(CESAGAN) and a new bootstrap-ping training
procedure. The CESAGAN is a modification ofthe self-attention GAN that
incorporates an embedding fea-ture vector input to condition the training of
the discriminatorand generator. This allows the network to model
non-localdependency between game objects, and to count objects. Ad-ditionally,
to reduce the number of levels necessary to trainthe GAN, we propose a
bootstrapping mechanism in whichplayable generated levels are added to the
training set. Theresults demonstrate that the new approach does not only
gen-erate a larger number of levels that are playable but also gen-erates fewer
duplicate levels compared to a standard GAN
Micromorphological evidences of pedogenetic changes due to anthropic action in Amazonian Dark Earth in the Central Amazon, Brazil.
This study aimed to use micromorphology to assess the formation processes of ADE in the municipality of Iranduba, Brazil
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