2,246 research outputs found
Individual performances relative to season bests in major track running championship races are distance-, position- and sex-dependent
Objectives. To compare season’s best times preceding major championships (SBprior) and times achieved in major championship flat track races. Material and methods. 2320 men’s and 2312 women’s finishing times over 100 m, 400 m, 800 m, 1500 m and 5000 m at the International Association of Athletics Federations (IAAF) World Championships and Olympic Games from 1999 to 2019, and their SBprior, were obtained via IAAF open-access website. Paired t-tests were used to compare major championship times and SBprior for groups across sex in each event. Repeated measures ANOVA was used to examine differences in the percentage of SBprior achieved in the major championship races (%SBprior) between groups and sexes. Results. Finishing time performances were generally slower than SBprior. The difference between SBprior and championship performances increased with distance run and across preliminary rounds and finals. Differences in %SBprior between sexes were found in non-medal finalists in the 800 m and 5000 m (p < 0.001, ES ≥ 0.72). Conclusions. 1500 m and 5000 m athletes competing at major championships should train and be physiologically prepared to sustain non-even paces and produce a fast endspurt to achieve an optimal performance
Network coevolution drives segregation and enhances Pareto optimal equilibrium selection in coordination games
In this work we assess the role played by the dynamical adaptation of the
interactions network, among agents playing Coordination Games, in reaching
global coordination and in the equilibrium selection. Specifically, we analyze
a coevolution model that couples the changes in agents' actions with the
network dynamics, so that while agents play the game, they are able to sever
some of their current connections and connect with others. We focus on two
update rules: Replicator Dynamics (RD) and Unconditional Imitation (UI). We
investigate a Pure Coordination Game (PCG), in which choices are equivalent,
and on a General Coordination Game (GCG), for which there is a risk-dominant
action and a payoff-dominant one. The network plasticity is measured by the
probability to rewire links. Changing this plasticity parameter, there is a
transition from a regime in which the system fully coordinates in a single
connected component to a regime in which the system fragments in two connected
components, each one coordinated on a different action (either if both actions
are equivalent or not). The nature of this fragmentation transition is
different for different update rules. Second, we find that both for RD and UI
in a GCG, there is a regime of intermediate values of plasticity, before the
fragmentation transition, for which the system is able to fully coordinate in a
single component network on the payoff-dominant action, i. e., coevolution
enhances payoff-dominant equilibrium selection for both update rules.Comment: 13 pages, 8 figures, submitted to Scientific Report
Network coevolution drives segregation and enhances Pareto optimal equilibrium selection in coordination games
In this work we assess the role played by the dynamical adaptation of the interactions network, among agents playing Coordination Games, in reaching global coordination and in the equilibrium selection. Specifically, we analyze a coevolution model that couples the changes in agents’ actions with the network dynamics, so that while agents play the game, they are able to sever some of their current connections and connect with others. We focus on two action update rules: Replicator Dynamics (RD) and Unconditional Imitation (UI), and we define a coevolution rule in which, apart from action updates, with a certain rewiring probability p, agents unsatisfied with their current connections are able to eliminate a link and connect with a randomly chosen neighbor. We call this probability to rewire links the ‘network plasticity’. We investigate a Pure Coordination Game (PCG), in which choices are equivalent, and on a General Coordination Game (GCG), for which there is a risk-dominant action and a payoff-dominant one. Changing the plasticity parameter, there is a transition from a regime in which the system fully coordinates on a single connected component to a regime in which the system fragments in two connected components, each one coordinated on a different action (either if both actions are equivalent or not). The nature of this fragmentation transition is different for different update rules. Second, we find that both for RD and UI in a GCG, there is a regime of intermediate values of plasticity, before the fragmentation transition, for which the system is able to fully coordinate on a single component network on the payoff-dominant action, i.e., coevolution enhances payoff-dominant equilibrium selection for both update rules
Activity Patterns of Stenocercus iridescens in an Ecuadorian Coastal Agroecosystem: Is Temperature Important?
Circadian rhythms of Neotropical lizards have been poorly studied, which represents a problem when designing ecological studies or monitoring such species based on direct observations. In this work, 1000 m-long transects were established in an agroecosystem area of the Ecuadorian coast region to study the activity patterns of Stenocercus iridescens. The number of individuals (as a response variable) was correlated with local weather conditions: temperature, precipitation, and heliophany (duration of the solar brightness). We carried out the study in both dry and rainy seasons, and during different time ranges. The time range in which the transects were performed was the most important predictor, and the activity peak was established between 16:00 h and 18:00 h. Heliophany negatively affected lizard activity, but only on the days with higher heliophany during the dry season, whereas temperature was not a significant predictor. Our results suggest that in an area where temperature is relatively constant and the solar radiation is high, particularly during the dry season, the heliophany (an indirect measure of solar radiation) can affect ectotherm activity patterns more than temperature, particularly in open habitats such as agroecosystems
Pt(II) coordination complexes as visible light photocatalysts for the oxidation of sulfides using batch and flow processes
A new catalytic system for the photooxidation of sulfides based on Pt(ii) complexes is presented. The catalyst is capable of oxidizing a large number of sulfides containing aryl, alkyl, allyl, benzyl, as well as more complex structures such as heterocycles and methionine amino acid, with complete chemoselectivity. In addition, the first sulfur oxidation in a continuous flow process has been developedJ. A. would also like to thank the MICINN for their ‘Ramón y Cajal’ contract and the European Research Council (ERC-CG, contract number 647550
Supramolecular Networks Obtained by Block Copolymer Self-Assembly in a Polymer Matrix: Crystallization Behavior and Its Effect on the Mechanical Response
In recent years, there has been growing interest in the study of supramolecular networks obtained by self-assembly of amphiphilic molecules due to their responsive behavior to different external stimuli. The possibility of embedding supramolecular networks into polymer matrices opens access to a new generation of functional polymers with great potential for various applications. However, very little is known about how the dynamics of the supramolecular network is affected by diffusional and topological limitations imposed by the polymer matrix. In this work, we investigate the behavior of supramolecular networks embedded into a rubbery polymer. Crystallization-driven self-assembly of a poly(ethylene-block-ethylene oxide) (PE-b-PEO) diblock copolymer was used to generate supramolecular networks in dimethacrylate monomers, which were then photopolymerized at room temperature. PE-b-PEO self-assembles into nanoribbons with a semicrystalline PE core bordered by coronal chains of PEO, and the nanoribbons, in turn, bundle into lamellar aggregates with an average stacking period of around 45 nm. The nanoribbons are interconnected through crystalline nodes in a 3D network structure. Small-angle X-ray scattering experiments show that the polymer matrix preserves the structure of the supramolecular network and avoids its disintegration when the material is heated above the melting temperature of PE cores. Successive self-nucleation and annealing studies reveal that the polymer matrix does not influence the crystallization–melting processes of PE, which take place through the interconnected cores of the supramolecular network. In contrast, the matrix imposes strong effects of topological confinement on the crystallization of PEO, limiting the dimensions of the crystalline lamellae that can be formed. Mechanical tests show that the deformation capacity of these materials can be precisely tuned by programming the temperature within the melting range of the supramolecular network. This behavior was also characterized by shape memory cyclic tests.The financial support of the following institutions is gratefully acknowledged: National Research Council (CONICET, Argentina), National Agency for the Promotion of Research, Technological Development and Innovation (AgenciaI + D + i, Argentina), and University of Mar del Plata. This work has received funding from the Basque Government through grant IT1503-22. R.N.S. thanks Iberoamerican Association of Postgraduate Universities (AUIP) for a mobility fellowship
Las divergencias socioeconómicas territoriales como alternativa metodológica del ordenamiento territorial en México
This paper examines the territorial socio-economic differences arising from the inconsistency between development level and socio-economic potential in each of the Mexican states. To begin with we present the theoretical positions which explain the contribution of Geography with regard to spatial management studies. Then we proceed to look at the basic features of development levels and socio-economic potential of the Mexican states; this is followed by the analysis of their territorial differences. We hope our research findings can contribute to setting up national criteria necessary to support spatial management studies in Mexico.El presente trabajo tiene como objetivo revelar las divergencias socioeconómicas de las entidades federativas de México. En una primera parte, se abordan, en forma breve, posiciones teóricas adoptadas en los trabajos de ordenamiento territorial en México. A continuación, se describen las características de los indicadores seleccionados que configuran los niveles de desarrollo y potencial socioeconómicos de las entidades federativas. Se concluye con la descripción de las divergencias territoriales, como noción cognoscitiva que posibilitó proponer criterios generales para orientar el ordenamiento territorial del paí
Isolation and transfection of strawverry protoplasts for gene editing
Strawberry is the most economically important soft fruit. The improvement of the organoleptic qualities of ripe fruit and the postharvest shelf life are main objectives of strawberry breeding programs. Fruit softening is mainly due to the disassembly of cell walls and the dissolution of middle lamella. In strawberry, functional analyses of genes encoding polygalacturonases (PGs) indicate that these enzymes play a key role in fruit softening, i.e. the antisense downregulation of PG genes FaPG1 or FaPG2 increased fruit firmness and postharvest shelf life (Paniagua et al., 2020). These results suggest that PG encoding genes are excellent targets for gene editing to improve strawberry fruit quality. Transfection of protoplasts with CRISPR/Cas9 ribonucleoprotein complexes is currently being explored in many species to produce DNA-free edited plants. In this research, a protocol for strawberry protoplasts transfection has been optimized with the final goal of producing non-transgenic strawberry plants with the FaPG1 gene edited. Protoplasts were isolated from 9 weeks old in vitro grown plants of Fragaria x ananassa, cv. ‘Chandler’, micropropagated in Murashige and Skoog (MS) medium supplemented with 2 mg/L of BA. Protoplast extraction and purification was performed as described by Barceló et al. (2019). Using this protocol, a yield of 1 x 105 protoplast/g fresh tissue was obtained and nearly 50-70% of them were viable. Protoplasts were transfected with the plasmid pHBT-sGFP(S65T)-NOS using a PEG-mediated transformation system, as reported by Yoo et al. (2007). To improve the efficiency of protoplast transfection, different variables were evaluated: PEG concentration, time of incubation on PEG and DNA concentration. At 48 h after transfection, the highest percentage of protoplasts showing GFP expression, 18%, was obtained with 15 minutes incubation in 20% of PEG and 5 µg of DNA
Sensitisation to Act 2d in patientsallergic to Alternaria alternanta: an epiphenomenom without clinical significance?
In the last few years, the introduction of microarrays in the diagnosis of type I allergy is allowing the clinicians to have a much more accurate picture of their allergenic profile. However, the simultaneous measurement of specific
IgE to multiple molecules can show unexpected sensitisations, without knowing their clinical relevance. For instance, we have been observing a high prevalence
(74%) of sensitisation to Act d 2 (the thaumatin of kiwifruit) in patients sensitised to Alt a 1 (major allergen of Alternaria alternata) with a confirmed allergy to this mould. The aim of the present study was to clarify if there was any clinical relevance in this finding
A bifunctional photoaminocatalyst for the alkylation of aldehydes: Design, analysis, and mechanistic studies
This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright ©2018 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/abs/10.1021/acscatal.8b01331A bifunctional photoaminocatalyst based on imidazolidinone and thioxanthone is presented. The preparation of these catalysts proceeds in a two-step synthesis that allows an easy tuning of the steric properties. The photophysical and electrochemical data of the imidazolidinone photocatalysts have been determined, indicating that the catalysts can work under visible light conditions. To corroborate the experimental observations, ground state geometry optimization and energy transition studies of thioxanthone and bifunctional catalyst 4c were optimized by time-dependent density functional theory (TD DFT) calculations. The alkylation of aldehydes with this photoaminocatalyst works with high enantioselectivities and yields due to the stereoelectronic properties of the catalyst. A rational mechanistic cycle based on different mechanistic experiments, TD DFT calculations, and laser flash photolysis is presentedThe Spanish Government (CTQ2015-64561-R) and the European Research Council (ERC-CG, Contract 647550) are acknowledge
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