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https://www.readbyqxmd.com/read/28878562/flexural-edge-waves-generated-by-steady-state-propagation-of-a-loaded-rectilinear-crack-in-an-elastically-supported-thin-plate
#1
Andrea Nobili, Enrico Radi, Luca Lanzoni
The problem of a rectilinear crack propagating at constant speed in an elastically supported thin plate and acted upon by an equally moving load is considered. The full-field solution is obtained and the spotlight is set on flexural edge wave generation. Below the critical speed for the appearance of travelling waves, a threshold speed is met which marks the transformation of decaying edge waves into edge waves propagating along the crack and dying away from it. Yet, besides these, and for any propagation speed, a pair of localized edge waves, which rapidly decay behind the crack tip, is also shown to exist...
August 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28773243/impact-load-behavior-between-different-charge-and-lifter-in-a-laboratory-scale-mill
#2
Zixin Yin, Yuxing Peng, Zhencai Zhu, Zhangfa Yu, Tongqing Li
The impact behavior between the charge and lifter has significant effect to address the mill processing, and is affected by various factors including mill speed, mill filling, lifter height and media shape. To investigate the multi-body impact load behavior, a series of experiments and Discrete Element Method (DEM) simulations were performed on a laboratory-scale mill, in order to improve the grinding efficiency and prolong the life of the lifter. DEM simulation hitherto has been extensively applied as a leading tool to describe diverse issues in granular processes...
July 31, 2017: Materials
https://www.readbyqxmd.com/read/28723814/validation-of-the-3-min-all-out-exercise-test-for-shuttle-running-prescription
#3
Anssi Saari, Nathan D Dicks, Mark E Hartman, Robert W Pettitt
A 3-min all-out exercise test (3MT) for running has been developed to determine critical speed (CS) and finite capacity for running speeds >CS (D') which allow for the prediction of time limits (TLIMs) associated with running different distances. Most team sports require shuttle running; however, the 3MT was validated for uninterrupted, track running and not shuttle running. The purpose of this study was to examine the efficacy of shuttle running 3MT to determine critical speed (CS) and D'. A total of 12 subjects were tested using a baseline 3MT along with three separate distance time-trials of all-out shuttle running to determine true CS and D'...
July 17, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28542091/normative-data-for-critical-speed-and-d-for-high-level-male-rugby-players
#4
Mark Kramer, Ida E Clark, Nick Jamnick, Cody Strom, Robert W Pettitt
The critical speed (CS) concept helps characterize the aerobic and anaerobic fitness of an athlete. Rugby players should hypothetically have modest CS values but extremely high curvature constant (D') values, yet, normative data are currently unavailable. To develop normative data of CS and D' for high-level male rugby players, a total of 30 male rugby players, were recruited from the Eastern Cape of South Africa. All subjects performed the running 3-min all-out exercise test (3 MT) using global positioning system (GPS) technology to determine CS and D'...
March 8, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28514809/iso-duration-determination-of-d%C3%A2-and-cs-under-laboratory-and-field-conditions
#5
Christoph Triska, Bettina Karsten, Alfred Nimmerichter, Harald Tschan
Whilst Critical Speed (CS) has been successfully translated from the laboratory into the field, this translation is still outstanding for the related maximum running distance (D'). Using iso-duration exhaustive laboratory and field runs, this study investigated the potential interchangeable use of both parameters, D' and CS. After an incremental exercise test, 10 male participants (age: 24.9±2.1 yrs; height: 180.8±5.8 cm; body mass: 75.3±8.6 kg; V̇ ˙VO2peak 52.9±3.1 mL∙min(-1)∙kg(-1)) performed 3 time-to-exhaustion runs on a treadmill followed by 3 exhaustive time-trial runs on a-400 m athletics outdoor track...
July 2017: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/28034367/dendritic-trafficking-faces-physiologically-critical-speed-precision-tradeoffs
#6
Alex H Williams, Cian O'Donnell, Terrence J Sejnowski, Timothy O'Leary
Nervous system function requires intracellular transport of channels, receptors, mRNAs, and other cargo throughout complex neuronal morphologies. Local signals such as synaptic input can regulate cargo trafficking, motivating the leading conceptual model of neuron-wide transport, sometimes called the 'sushi-belt model' (Doyle and Kiebler, 2011). Current theories and experiments are based on this model, yet its predictions are not rigorously understood. We formalized the sushi belt model mathematically, and show that it can achieve arbitrarily complex spatial distributions of cargo in reconstructed morphologies...
December 30, 2016: ELife
https://www.readbyqxmd.com/read/28007073/closing-in-on-the-pumpkin-trial-of-the-jarvik-2015-ventricular-assist-device
#7
REVIEW
J Timothy Baldwin, Iki Adachi, John Teal, Christopher A Almond, Robert D Jaquiss, M Patricia Massicotte, Kurt Dasse, Flora S Siami, Victor Zak, Jonathan R Kaltman, William T Mahle, Robert Jarvik
The Infant Jarvik ventricular assist device (VAD; Jarvik Heart, Inc., New York, NY) has been developed to support the circulation of infants and children with advanced heart failure. The first version of the device was determined to have elevated hemolysis under certain conditions. The objective of this work was to determine appropriate modifications to the Infant Jarvik VAD that would result in acceptably low hemolysis levels. In vitro hemolysis testing revealed that hemolysis was related to the shape of the pump blade tips and a critical speed over which hemolysis would occur...
January 2017: Seminars in Thoracic and Cardiovascular Surgery. Pediatric Cardiac Surgery Annual
https://www.readbyqxmd.com/read/27925233/quantification-and-analysis-of-leaflet-flutter-on-biological-prosthetic-cardiac-valves
#8
Artur H de F Avelar, Jean A Canestri, Camila Bim, Maíra G M Silva, Rudolf Huebner, Marcos Pinotti
The use of porcine or bovine pericardium biological cardiac valves has as its main disadvantage a relatively short lifespan, with failures due to calcification and fatigue. Increasing these valves' durability constitutes a great challenge. An understudied phenomenon is the effect of flutter, an oscillation of the leaflets that can cause regurgitation and accelerate calcification and fatigue. As a starting point to study how to reduce or prevent these oscillations, a method was developed to quantify the flutter frequencies occurring at the point of the valve's full opening...
December 7, 2016: Artificial Organs
https://www.readbyqxmd.com/read/27463968/instantaneous-flow-structures-and-opportunities-for-larval-settlement-barnacle-larvae-swim-to-settle
#9
Ann I Larsson, Lena M Granhag, Per R Jonsson
Water flow affects settlement of marine larvae on several scales. At the smallest scale local flow regime may control the probability of adhesion to the substrate. Our aim was to mechanistically understand the transition from suspended to attached larvae in turbulent flow. Recently it was proposed that opportunities for larval settlement in turbulent boundary layers depend on time windows with suitable instantaneous flow properties. In flume flow we characterized the proportion of suitable time windows in a series of flow velocities with focus on the near-bed flow...
2016: PloS One
https://www.readbyqxmd.com/read/27442329/modeling-of-running-performances-in-humans-comparison-of-power-laws-and-critical-speed
#10
Badrane Zinoubi, Henry Vandewalle, Tarak Driss
Zinoubi, B, Vandewalle, H, and Driss, T. Modeling of running performances in humans: comparison of power laws and critical speed. J Strength Cond Res 31(7): 1859-1867, 2017-The concepts of power law and critical speed (SCrit) have been applied to the analysis of individual running performances. We have analyzed the results of 2 exceptional runners (Nurmi and Gebrselassie) and 11 physical education students (PESs) who performed 3 exhausting running exercises. Power laws can accurately describe the relationships between exhaustion time (tlim) and distance (Dlim) or speed (S) (Equation is included in full-text article...
July 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27431779/severe-hypoxemia-induced-by-prolonged-expiration-and-reduced-frequency-breathing-during-submaximal-swimming
#11
Argyris G Toubekis, Nikolaos Beidaris, Petros G Botonis, Maria Koskolou
The purpose of this study was to examine the metabolic responses during submaximal swimming with self-selected normal breathing (N) and prolonged expiration along with reduced frequency breathing (RB). Ten male swimmers (age: 23.1 ± 2.2 years; VO2max: 47.3 ± 7.2 ml · kg(-1) · min(-1)) performed 75-, 100-, 175-, 200-, 275-, 300-, 375- and 400-m trials with N and RB at intensity corresponding to 90% of the critical speed. In RB condition, all trials longer than 75 m were interspersed with 25 m of self-selected N in regular intervals...
June 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/27379951/validity-of-treadmill-derived-critical-speed-on-predicting-5000-meter-track-running-performance
#12
RANDOMIZED CONTROLLED TRIAL
Alfred Nimmerichter, Nina Novak, Christoph Triska, Bernhard Prinz, Brynmor C Breese
Nimmerichter, A, Novak, N, Triska, C, Prinz, B, and Breese, BC. Validity of treadmill-derived critical speed on predicting 5,000-meter track-running performance. J Strength Cond Res 31(3): 706-714, 2017-To evaluate 3 models of critical speed (CS) for the prediction of 5,000-m running performance, 16 trained athletes completed an incremental test on a treadmill to determine maximal aerobic speed (MAS) and 3 randomly ordered runs to exhaustion at the [INCREMENT]70% intensity, at 110% and 98% of MAS. Critical speed and the distance covered above CS (D') were calculated using the hyperbolic speed-time (HYP), the linear distance-time (LIN), and the linear speed inverse-time model (INV)...
March 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27321993/physical-characterization-of-unfilled-and-nanofilled-dental-resins-static-versus-dynamic-mechanical-properties
#13
Parisa Saen, Mohammad Atai, Azizollah Nodehi, Laleh Solhi
OBJECTIVE: The aim of this study was to evaluate the mechanical properties of dental resins and dental nanocomposites by means of 3-point bending, 4-point bending and piston-on-three ball biaxial static tests and also to investigate their dynamic mechanical properties. The obtained results from the static 3-point bending test also were compared with the corresponding mode in DMTA. METHODS: The hydrophilic surface of the inorganic OX-50 particles was treated with γ-MPS and the resulting silanized OX-50 was characterized using FTIR and TGA...
August 2016: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/27197057/applying-the-critical-speed-concept-to-racing-strategy-and-interval-training-prescription
#14
REVIEW
Robert W Pettitt
The use of personal records (PRs) for running different distances may be used to derive critical speed (CS) and the finite capacity for running speeds exceeding CS (D'). Using CS and D', individualized speed-time and distance-time relationships can be modeled (ie, time limits associated with running at a given speed or a given distance can be derived via linear regression with a high degree of accuracy). The running 3-min all-out exercise test (3 MT) has emerged as a method for estimating CS and D' on a large group of athletes in a single visit...
October 2016: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/27044992/the-pulsatility-volume-index-an-indicator-of-cerebrovascular-compliance-based-on-fast-magnetic-resonance-imaging-of-cardiac-and-respiratory-pulsatility
#15
Marta Bianciardi, Nicola Toschi, Jonathan R Polimeni, Karleyton C Evans, Himanshu Bhat, Boris Keil, Bruce R Rosen, David A Boas, Lawrence L Wald
The influence of cardiac activity on the viscoelastic properties of intracranial tissue is one of the mechanisms through which brain-heart interactions take place, and is implicated in cerebrovascular disease. Cerebrovascular disease risk is not fully explained by current risk factors, including arterial compliance. Cerebrovascular compliance is currently estimated indirectly through Doppler sonography and magnetic resonance imaging (MRI) measures of blood velocity changes. In order to meet the need for novel cerebrovascular disease risk factors, we aimed to design and validate an MRI indicator of cerebrovascular compliance based on direct endogenous measures of blood volume changes...
May 13, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/27003111/three-minute-all-out-test-in-swimming
#16
Ming-Chang Tsai, Scott G Thomas
PURPOSE: To validate the 3-minute all-out exercise test (3MT) protocol against the traditional critical-speed (CS) model (CSM) in front-crawl swimming. METHODS: Ten healthy swimmers or triathletes (mean ± SD age 35.2 ± 10.5 y, height 176.5 ± 5.4 cm, body mass 69.6 ± 8.2 kg) completed 5 tests (3MT, 100m, 200m, 400m, 800m) over 2 wk on separate days. Traditional CS and anaerobic distance capacity (D') were determined for each of the 3 traditional CSMs (linear distance-time, LIN; linear speed/time, INV; nonlinear time-speed, NLIN) from the 4 set-distance time trials...
January 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/26849787/the-v-combining-dot-above-o2-kinetics-of-maximal-and-supramaximal-running-exercises-in-sprinters-and-middle-distance-runners
#17
COMPARATIVE STUDY
Paulo C do Nascimento Salvador, Juliano Dal Pupo, Ricardo D De Lucas, Rafael A de Aguiar, Francimara B Arins, Luiz G A Guglielmo
do Nascimento Salvador, PC, Dal Pupo, J, De Lucas, RD, de Aguiar, RA, Arins, FB, and Guglielmo, LGA. The V[Combining Dot Above]O2 kinetics of maximal and supramaximal running exercises in sprinters and middle-distance runners. J Strength Cond Res 30(10): 2857-2863, 2016-The aim of this study was to compare the V[Combining Dot Above]O2 kinetics parameters during maximal and supramaximal running exercises in sprinters (SPR) and middle-distance runners (MDR). Twelve SPR (age 20.6 ± 3.4 years; and body mass 74...
October 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/26764659/topological-distance-dependent-transition-in-flocks-with-binary-interactions
#18
Biplab Bhattacherjee, Shradha Mishra, S S Manna
We have studied a flocking model with binary interactions (binary flock), where the velocity of an agent depends on the velocity of only another agent and its own velocity, topped by the angular noise. The other agent is selected as the nth topological neighbor; the specific value of n being a fixed parameter of the problem. On the basis of extensive numerical simulation results, we argue that for n = 1, the phase transition from the ordered to the disordered phase of the flock is a special kind of discontinuous transition...
December 2015: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
https://www.readbyqxmd.com/read/26580942/-early-childhood-growth-and-development
#19
Melitón Arce
This article describes and discusses issues related to the process of childhood growth and development, with emphasis on the early years, a period in which this process reaches critical speed on major structures and functions of the human economy. We reaffirm that this can contribute to the social availability of a generation of increasingly better adults, which in turn will be able to contribute to building a better world and within it a society that enjoys greater prosperity. In the first chapter, we discuss the general considerations on the favorable evolution of human society based on quality of future adults, meaning the accomplishments that today’s children will gain...
July 2015: Revista Peruana de Medicina Experimental y Salud Pública
https://www.readbyqxmd.com/read/26565253/squeeze-out-dynamics-of-nanoconfined-water-a-detailed-nanomechanical-study
#20
Shah H Khan, Peter M Hoffmann
In this study, we present a detailed analysis of the squeeze-out dynamics of nanoconfined water confined between two hydrophilic surfaces measured by small-amplitude dynamic atomic force microscopy. Explicitly considering the instantaneous tip-surface separation during squeeze-out, we confirm the existence of an adsorbed molecular water layer on mica and at least two hydration layers. We also confirm the previous observation of a sharp transition in the viscoelastic response of the nanoconfined water as the compression rate is increased beyond a critical value (previously determined to be about 0...
October 2015: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
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