Muscular and non-muscular contributions to maximum power cycling in children and adults: implications for developmental motor control

This article is available open access through the publisher’s website at the link below.During submaximal cycling, children demonstrate a different distribution between muscular and non-muscular (gravitational and motion-dependent) forces when compared with adults. This is partly due to anthropometric differences. In this study, we tested the hypothesis that during maximum power cycling, children would construct the task (in terms of the distribution between muscular and non-muscular pedal power) similarly to adults. Eleven children (aged 8–9 years) and 13 adults (aged 20–40 years) performed a maximal isokinetic cycling task over 3 s at 115 r.p.m. Multivariate analyses of variance revealed no significant differences in normalized maximum, minimum and average positive non-muscular pedal power between children and adults (Wilks' λ=0.755, F3,20=2.17, P=0.124). Thus, maximum cycling is a developmental `self-scaling' task and age-related differences in muscular power production are not confounded by differences in anthropometry. This information is useful to researchers who wish to differentiate between muscular and non-muscular power when studying developmental motor control. In addition to the similarities in the distribution between muscular and non-muscular pedal power, we found age-related differences in the relative joint power contributions to total pedal power. In children, a significantly smaller proportion of total pedal power was generated at the ankle joint (6.1±5.4% for children and 12.6±3.2% for adults), whilst relatively more power was generated at the knee and hip joints. These results suggest that intermuscular coordination may be contributing to children's limits in maximum power production during multi-joint tasks

Learning How to Count: A High Multiplicity Search for the LHC

We introduce a search technique that is sensitive to a broad class of signals with large final state multiplicities. Events are clustered into large radius jets and jet substructure techniques are used to count the number of subjets within each jet. The search consists of a cut on the total number of subjets in the event as well as the summed jet mass and missing energy. Two different techniques for counting subjets are described and expected sensitivities are presented for eight benchmark signals. These signals exhibit diverse phenomenology, including 2-step cascade decays, direct three body decays, and multi-top final states. We find improved sensitivity to these signals as compared to previous high multiplicity searches as well as a reduced reliance on missing energy requirements. One benefit of this approach is that it allows for natural data driven estimates of the QCD background.Comment: 36 pages, 12 Figures, 5 Tables; journal versio

Cinétique de racémisation dans les protéines d’ossements pléistocènes du Sud de la France

Nous avons suivi l'évolution des taux de racémisation de l'acide aspartique et de l'acide glutamique des protéines d'ossements fossiles. Ces ossements proviennent de huit sites préhistoriques du Sud de la France dont nous avons sélectionné douze niveaux stratigraphiques d'âges compris entre 20 000 ans et 1 million d'années. Dans un premier temps, nous avons mesuré les taux de racémisation sur l'ensemble des acides aminés contenus dans les ossements, sans sélection préalable. Les résultats obtenus par cette approche sont dispersés et inutilisables en géochronologie. Dans un second temps, nous avons réalisé une sélection des protéines fossiles basée sur leur taille (extraction par l'EDTA suivie d'une dialyse) ou sur leur solubilité (matériel insoluble dans un faible volume de HCI 1M). Les matériels protéiques issus de ces sélections présentent des taux de racémisation dont les évolutions se font en deux parties. Les taux de racémisation croissent rapidement dans un premier intervalle qui s'étend jusqu'à environ 50 000 ans. Dans une seconde phase, la racémisation progresse beaucoup plus lentement. Ce comportement cinétique s'apparente à celui observé à de nombreuses reprises dans des séries de fossiles carbonates. Nous avons testé l'ajustement d'une fonction bi-exponentielle à chacune des quatre séries de valeurs (Asp et Glu, extraits EDTA et HCI). Les ajustements sont satisfaisants pour l'acide aspartique, tandis que les valeurs de l'acide glutamique sont plus dispersées. Ce type de cinétique pourrait être provoqué par les contraintes stériques et électrostatiques subies par les acides aminés dans les protéines. Des courbes de même nature ont été décrites par plusieurs auteurs à partir de coquilles et de coraux. La confirmation de ces résultats sur un plus grand nombre de sites ouvrirait la voie à la datation absolue des ossements fossiles dans un très large intervalle de temps.The racemization ratios of aspartic and glutamic acids in fossil bone proteins were studied. The bones originated from eight prehistoric sites of southern France from which twelve stratigraphie levels were selected. Their ages are included between 20,000 to 1,000,000 years. Firstly, the racemization ratios were determined in total extract (whole of amino acids present in bone obtained by 6 M HCI hydrolysis of the bone powder). The results of such an approach are scattered and they are of no use to geochronology. Next, fossil proteins were selected according to their molecular weights by extraction with 0.5 M EDTA and 10,000 Dalton dialysis or according to their solubilities by dissolution in 1 M HCI, 8 ml.g-1 and centrifugation. The racemization ratios determined on both dialysed extract and HCI insoluble part exhibit evolutions in two parts. Each of the two parts corresponds to a "pseudo first-order" kinetics, but in the first period (until ca. 50,000 years) racemization ratios increase rapidly, while in the second one (ca. 100,000 -1 My) the apparent rate constants are lower. Such a behaviour was previously described in various series of carbonated fossils (shells, corals…). We tested the fit of a sum of two exponential functions to the four series of values (Asp and GIu, EDTA + dialysis or HCI insoluble). The fits are good for aspartic acid, while the results for glutamic acid are more scattered. The bi-exponential kinetics could be caused by steric and electrostatic interactions between amino acids inside proteins. The corroboration of this result on a large number of sites should allow the absolute dating of fossil bones within a wide time interval.Wir haben die Entwicklung der Razemisierungsrate von Asparaginsâure und Glutaminsàure der Protéine fossiler Gebeine untersucht. Diese Gebeine stammen von acht pràhistorischen Fundstellen, von denen wir zwôlf stratigraphische Niveaus von einem Alter zwischen 20 000 Jahren und einer Million Jahren ausgewâhlt haben. Zuerst haben wir die Razemisierungsrate aller in den Gebeinen enthaltenen Aminosâuren gemessen, ohne vorherige Auswahl. Die auf diese Weise erhaltenen Ergebnisse sind zerstreut und in der Geochronologie nicht verwendbar. In einem zweiten Schritt haben wir eine Auswahl der fossilen Gebeine getroffen, indem wir uns auf ihre Grosse oder ihre Lôslichkeit stùtzten. Das Proteinmaterial, das wir bei dieser Auswahl gewannen, zeigt eine Razemisierungsrate, deren Entwicklung sich in zwei Teilen vollzieht. Die Razemisierungsraten nehmen in einem ersten Intervall, das sich bis etwa 50 000 Jahre erstreckt, rasch zu. In einer zweiten Phase geht die Razemisierung sehr viel langsamer voran. Dieses kinetische Verhalten âhnelt dem, das man immer wieder in Serien karbonisierter Fossile beobachtet. Wir haben die Anpas-sung einer Bi-Exponential-Funktion an jede der vier Serien von Werten getestet. Die Anpassungen sind, was die Asparaginsâure betrifft, zufriedenstellend, wohingegen die Werte der Glutaminsàure mehr zerstreut sind. Im Zuge einer uberlegung zu den durch die Razemisierung der Aminosâuren in den Proteinen erlittenen Belastungen hatte man die Existenz einer Bi-Exponential-Kinetik vorgeschlagen. Es scheint, dass die Aminosâuren der Knochen-Proteine sich nach demselben Kinetik-Typus richten. Sollte sich dieses Ergebnis an einer grôsseren Zahl von Fundstellen bestàtigen so ware der Weg zu einer absoluten Datierung der fossilen Gebeine fur einen sehr grossen Zeitraum geôffnet

A perfusion culture system for assessing bone marrow stromal cell differentiation on PLGA scaffolds for bone repair

Biomaterials development for bone repair is currently hindered by the lack of physiologically relevant in vitro testing systems. Here we describe the novel use of a bi-directional perfusion bioreactor to support the long term culture of human bone marrow stromal cells (BMSCs) differentiated on polylactic co-glycolic acid (PLGA). Primary human BMSCs were seeded onto porous PLGA scaffolds and cultured in static vs. perfusion culture conditions for 21 days in osteogenic vs. control media. PLGA scaffolds were osteoconductive, supporting a mature osteogenic phenotype as shown by the upregulation of Runx2 and the early osteocyte marker E11. Perfusion culture enhanced the expression of osteogenic genes Osteocalcin and Osteopontin. Extracellular matrix deposition and mineralisation were spatially regulated within PLGA scaffolds in a donor dependant manner. This, together with the observed upregulation of Collagen type X suggested an environment permissive for the study of differentiation pathways associated with both intramembranous and endochondral ossification routes of bone healing. This culture system offers a platform to assess BMSC behavior on candidate biomaterials under physiologically relevant conditions. Use of this system may improve our understanding of the environmental cues orchestrating BMSC differentiation and enable fine tuning of biomaterial design as we develop tissue-engineered strategies for bone regeneration

Simulating the Hydrodynamics of Self-Propelled Colloidal Clusters using Stokesian Dynamics

Self-propelled clusters are involved in many technological applications such as in material science and biotechnology, and understanding their interaction with the fluid that surrounds them is of a great importance. We present results of swimming velocity and energy dissipation obtained through Stokesian dynamics simulations of self-propelled clusters. The clusters are of diffusion limited aggregates (DLA), consisting of force- and torque-free spherical particles. The number of particles per cluster ranges from 100 to 400, and with two fractal dimensions of 2.1 and 2.4. The clusters are self-propelled by imposing an explicit gait velocity applied in the x, y and z directions. It is found that the swimming velocity of the cluster and the energy dissipation are strongly dependent on the number of particles in the cluster and its fractal dimension, and on the orientation of the imposed explicit gait velocity. It was found that the rotational velocity of the self-propelled clusters decreases as the number of particles within the cluster is increased, n line with experimental observations reported recently in the literature

Self – Propelled Nanofluids a Path to a highly Effective Coolant

We propose a new self-propelled nanofluid having advantageous thermal and rheological properties at the same time. The nanofluid consists of a low volume fraction of self-propelled particles known as Artificial Bacterial Flagella (ABF), which will swim as pushers in a manner similar to the swimming of E-coil microorganisms with flagella. A theoretical model is introduced, describing the mechanisms responsible for the reduction of viscosity. The model shows that the swimming velocity of the particle and its geometry play an essential role in the reduction of the suspension viscosity. The results obtained from the theoretical model compare qualitatively with experiments in the literature. The model shows a significant decrease in viscosity at very low volume fractions, and that the viscosity of the suspension is reduced as the volume fraction of the particles increases. Using an in-house finite volume code, we numerically simulate natural convection effects in our ABF self-propelled nanofuid inside a square cavity heated from its vertical sides. Simulations are conducted at volume fractions of 0.7%, 0.8% and 0.83%, comparing the performance of a self-propelled nanofluid with conventional non-active nanofluids (i.e. carbon nanotubes in water). The results show that the heat transfer rate measured by the Nusselt number is three times higher than for the case of classical nanofluids and pure water at the same operating conditions and 0.83% volume fraction of particles. Also, due to the very dilute volume fractions of particles in the proposed nanofluid, their stability can endure for long operating times. There is also a significant decrease in the viscosity (around 25 times lower than water) which will result in a significant reduction in the pumping power

A Reinforcement Learning Framework for Spiking Networks with Dynamic Synapses

An integration of both the Hebbian-based and reinforcement learning (RL) rules is presented for dynamic synapses. The proposed framework permits the Hebbian rule to update the hidden synaptic model parameters regulating the synaptic response rather than the synaptic weights. This is performed using both the value and the sign of the temporal difference in the reward signal after each trial. Applying this framework, a spiking network with spike-timing-dependent synapses is tested to learn the exclusive-OR computation on a temporally coded basis. Reward values are calculated with the distance between the output spike train of the network and a reference target one. Results show that the network is able to capture the required dynamics and that the proposed framework can reveal indeed an integrated version of Hebbian and RL. The proposed framework is tractable and less computationally expensive. The framework is applicable to a wide class of synaptic models and is not restricted to the used neural representation. This generality, along with the reported results, supports adopting the introduced approach to benefit from the biologically plausible synaptic models in a wide range of intuitive signal processing

Phosphorylation mechanisms in intensive care medicine

INTRODUCTION: The phosphorylation states of proteins, lipids, carbohydrates, amino acids, and nucleotides control the mechanisms behind nearly all cellular functions. Therefore, not surprisingly, recent findings have shown that alterations in these phosphorylation pathways play a central role in the development and progression of many disease states. This review provides a brief summary of the function and activity of various phosphorylation mechanisms, outlines some of the major phosphorylation signaling cascades, and describes the role of these phosphorylation mechanisms in intensive care medicine. METHODS: This article will comprise a comprehensive review of the literature in the context of intensive care medicine. Specifically, we will discuss the involvement of phosphorylation in the pathogenesis, diagnosis, and treatment of heart failure, myocardial infarction, stroke, respiratory failure, ventilation-induced lung injury, traumatic brain injury, acute organ failure, systemic sepsis, and shock. CONCLUSION: Phosphorylation mechanisms clearly play an important role in many pathologies and treatment strategies of intensive care and therefore further understanding of these mechanisms may lead to the development of novel therapies and improved patient care

Near-infrared photometry of WISE J085510.74-071442.5

Indexación: Web of ScienceAims. We aim at obtaining near-infrared photometry and deriving the mass, age, temperature, and surface gravity of WISE J085510.74 071442.5 (J0855 0714), which is the coolest object beyond the solar system currently known. Methods. We used publicly available data from the archives of the Hubble Space Telescope (HST) and the Very Large Telescope (VLT) to determine the emission of this source at 1.153 mu m (F110W) and 1.575 mu m (CH4-o ff). J0855 0714 was detected at both wavelengths with a signal-to-noise ratio of approximate to 10 (F110W) and approximate to 4 (CH4-off) at the peak of the corresponding point-spread-functions. Results. This is the first detection of J0855 0714 in the H-band wavelengths. We measured 26.31 +/- 0.10 and 23.22 +/- 0.35 mag in F110W and CH4-o ff (Vega system). J0855 0714 remains unresolved in the HST images that have a spatial resolution of 0.22 0 0. Companions at separations of 0.5 AU (similar mass and brightness) and at similar to 1 AU approximate to 1 mag fainter in the F110W filter) are discarded. By combining the new data with published photometry, including non-detections, we build the spectral energy distribution of J0855 0714 from 0.89 through 22.09 mu m, and contrast it against current solar-metallicity models of planetary atmospheres. We determine that the best spectral fit yields a temperature of 225 250 K, a bolometric luminosity of log L/L-circle dot = 8 : 57, and a high surface gravity of log g = 5 : 0 (cm s(2)), which suggests an old age although a gravity this high is not fully compatible with evolutionary models. After comparing our data with the cooling theory for brown dwarfs and planets, we infer a mass in the interval 2 10 MJup for ages of 1 12 Gyr and high atmospheric gravities of log g greater than or similar to 3.5 (cm s(2)). If it had the age of the Sun, J0855 0714 would be a approximate to 5-M-Jup free-floating planetary-mass object. Conclusions. J0855 0714 meets the mass values previously determined for free-floating planetary-mass objects discovered in starforming regions and young stellar clusters. Based on extrapolations of the substellar mass functions of young clusters to the field, as many J0855 0714-like objects as M5-L2 stars may be expected to populate the solar neighborhood.http://www.aanda.org/articles/aa/pdf/2016/08/aa28662-16.pd