1,415 research outputs found
Analysis of a dry friction problem under small displacements: application to a bolted joint
This study presents an analysis of the problem of macroscopic contact of steel upon steel with dry friction, in the specific case of a bolted joint. The configurations of these types of joints result in very small displacements and interface sliding velocities. To understand how the system formed by the two surfaces in contact works, an experiment was carried out. The analysis of the results obtained made it possible to define the behavior of the system and to model the variations of the main parameters by original and continuous laws. These laws accurately correlate to all the results of the tests effectuated
Anurans Of A Remnant Forest In Urussanga, Santa Catarina, Southern Of Brazil
We provide a list of amphibians from a Submontane Forest remnant in Urussanga municipality, Santa Catarina, southern of Brazil. We sampling through visual and acoustic surveys in four distinct sites. Twenty-six species of anurans belonging to nine families were recorded, where nine species were rare, nine abundant, and eight common. Eleven reproductive modes were observed, with exotrophic tadpoles in still water (mode 1) being most frequent mode (38%). The period of highest vocalization activity occurred between October and January. Temperature, rainfall and air humidity were not correlated with the richness and abundance of calling males. Only photoperiod was positively correlated with the abundance of calling males and species richness. © 2016 Check List and Authors.12
SAPP: functional genome annotation and analysis through a semantic framework using FAIR principles
There are currently more than 150.000 sequenced genomes available from which considerable amounts of information can be extracted. However, annotation information is often not interoperable, static, lacks provenance and is quickly outdated. Keeping these datasets up-to-date, and interoperable is a challenging ..
Resistance training enhances delayed memory in healthy middle-aged and older adults: A randomised controlled trial
Objectives
High-intensity exercise is a potential therapeutic tool to postpone or prevent the onset of cognitive decline. However, there is a lack of sufficient evidence regarding the longitudinal effects of structured resistance training on cognitive function in healthy adults. The purpose of this study was to investigate the effect of two ecologically valid, intense 12-week resistance training programs on cognitive function in late middle-aged adults.
Design
Single-site parallel randomised controlled trial at the Department of Exercise Science strength and conditioning laboratory. Groups allocated by minimisation randomisation.
Methods
Forty-five healthy adults (age rangeâ=â41-69 years) were enrolled and randomised into A.) high-load, long rest resistance training (nâ=â14), or B.) moderate-load, short rest resistance training (nâ=â15) twice per week for 12 weeks, or a non-exercising control (nâ=â16). Follow-up within 7 days. Data were collected September 2016-December 2017. Cognitive function assessed using the CogState computerised battery. Assessors were blinded to participant group allocation. Secondary outcomes were maximal muscle strength and body composition.
Results
Forty-four participants were analysed in 2018. Delayed verbal memory performance was improved (pâ=â0.02) in resistance training groups (gâ=â0.67-0.79) when compared to the control group, with no differences between training groups. Likewise, increases in maximal muscle strength were observed (pâ<â0.01) in resistance training groups when compared to the control group, with no differences between training groups. No differences in body composition were observed. There were no adverse events or side-effects of the intervention.
Conclusions
12 weeks of intense resistance training improves delayed verbal memory irrespective of training design (i.e., high-load vs. moderate-load)
A randomized controlled trial of high-intensity exercise and executive functioning in cognitively normal older adults
Background
There is a paucity of interventional research that systematically assesses the role of exercise intensity and cardiorespiratory fitness, and their relationship with executive function in older adults. To address this limitation, we have examined the effect of a systematically manipulated exercise intervention on executive function.
Methods
Ninety-nine cognitively normal participants (ageâŻ=âŻ69.10 ± 5.2 years; nâŻ=âŻ54 female) were randomized into either a high-intensity cycle-based exercise, moderate-intensity cycle-based exercise, or no-intervention control group. All participants underwent neuropsychological testing and fitness assessment at baseline (preintervention), 6-month follow-up (postintervention), and 12-month postintervention. Executive function was measured comprehensively, including measures of each subdomain: Shifting, Updating/ Working Memory, Inhibition, Verbal Generativity, and Nonverbal Reasoning. Cardiorespiratory fitness was measured by analysis of peak aerobic capacity; VO2peak.
Results
First, the exercise intervention was found to increase cardiorespiratory fitness (VO2peak) in the intervention groups, in comparison to the control group (F =10.40, pâ€0.01). However, the authors failed to find mean differences in executive function scores between the high-intensity, moderate intensity, or inactive control group. On the basis of change scores, cardiorespiratory fitness was found to associate positively with the executive function (EF) subdomains of Updating/Working Memory (ÎČâŻ=âŻ0.37, pâŻ=âŻ0.01, râŻ=âŻ0.34) and Verbal Generativity (ÎČâŻ=âŻ0.30, pâŻ=âŻ0.03, râŻ=âŻ0.28) for intervention, but not control participants.
Conclusion
At the aggregate level, the authors failed to find evidence that 6-months of high-intensity aerobic exercise improves EF in older adults. However, it remains possible that individual differences in experimentally induced changes in cardiorespiratory fitness may be associated with changes in Updating/ Working Memory and Verbal Generativity
Electromagnetic radiation from superconducting string cusps
Cusps in superconducting cosmic strings produce strongly beamed
electromagnetic radiation. To calculate the energy emitted requires taking into
account the effect of the charge carriers on the string motion, which has
previously been done only heuristically. Here, we use the known exact solution
to the equations of motion for the case where the current is chiral to update
previous calculations for the total energy, spectrum and angular distribution
in that case. We analyze the dependence of the radiated energy on the cusp
parameters, and discuss which types of cusp dominate the total radiation
emitted from an ensemble.Comment: 12 pages, LaTex, 2 figure
Drum vortons in high density QCD
Recently it was shown that high density QCD supports of number of topological
defects. In particular, there are U(1)_Y strings that arise due to K^0
condensation that occurs when the strange quark mass is relatively large. The
unique feature of these strings is that they possess a nonzero K^+ condensate
that is trapped on the core. In the following we will show that these strings
(with nontrivial core structure) can form closed loops with conserved charge
and currents trapped on the string worldsheet. The presence of conserved
charges allows these topological defects, called vortons, to carry angular
momentum, which makes them classically stable objects. We also give arguments
demonstrating that vortons carry angular momentum very efficiently (in terms of
energy per unit angular momentum) such that they might be the important degrees
of freedom in the cores of neutron stars.Comment: 11 pages, accepted for publication in Physical Review
Particle Acceleration in Pulsar Wind Nebulae: PIC modelling
We discuss the role of particle-in-cell (PIC) simulations in unveiling the
origin of the emitting particles in PWNe. After describing the basics of the
PIC technique, we summarize its implications for the quiescent and the flaring
emission of the Crab Nebula, as a prototype of PWNe. A consensus seems to be
emerging that, in addition to the standard scenario of particle acceleration
via the Fermi process at the termination shock of the pulsar wind, magnetic
reconnection in the wind, at the termination shock and in the Nebula plays a
major role in powering the multi-wavelength signatures of PWNe.Comment: 32 pages, 16 figures, to appear in the book "Modelling Nebulae"
edited by D. Torres for Springer, based on the invited contributions to the
workshop held in Sant Cugat (Barcelona), June 14-17, 201
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