The Role of Effective Mass and Hand Speed in the Performance of Kung Fu Athletes Compared with Nonpractitioners

2007 ◽  
Vol 23 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Osmar Pinto Neto ◽  
Marcio Magini ◽  
Marcelo M. F. Saba
Keyword(s):  
Effective Mass ◽  
High Speed ◽  
Control Group ◽  
Impact Measurement ◽  
Ball Speed ◽  
Kung Fu ◽  
High Speed Video ◽  
Post Impact ◽  
Main Factor

The main goal of this article is to quantify the contribution of effective mass (me) and hand-speed (shi) on the palm strike performance of kung fu athletes (kung fu group) compared with nonpractitioners (control group). All subjects were asked to strike a basketball. Hand and ball speed (sbf) were determined by high-speed video analysis. The value for me was determined by an equation that does not depend upon post-impact measurement of the hand speed. The results show that kung fu athletes had greater shi (6.67 [SD 1.42] m/s), p = 0.042), higher me (2.62 [SD 0.33] kg, p = 0.004), and greater sbf (9.00 [SD 1.89] m/s), p = 0.004) than the nonpractitioners (5.04 [SD 0.57] m/s, 1.33 [SD 0.19] kg, and 5.72 [SD 0.44] m/s, respectively). Comparing the average values obtained for me and hand and forearm mass (m), it was found that for the control group me is statistically equal to m (p = 0.917), whereas for the kung fu group me is significant greater than m (p = 0.003). It is suggested that for impacts against heavier objects, the effective mass would be the main factor to distinguish a martial artstrained from an untrained subject.

Mechanics and aerodynamics of perching manoeuvres in a large bird of prey

2010 ◽  
Vol 114 (1161) ◽  
pp. 673-680 ◽  
Author(s):  
A. C. Carruthers ◽  
A. L. R. Thomas ◽  
S. M. Walker ◽  
G. K. Taylor
Keyword(s):  
High Speed ◽  
High Lift ◽  
Still Images ◽  
Video Cameras ◽  
Bird Of Prey ◽  
High Speed Video ◽  
Wing Profile ◽  
Large Bird ◽  
Flight Muscles

Abstract This paper reviews recent results on the mechanics and aerodynamics of perching in a large bird of prey, the Steppe Eagle Aquila nipalensis. Data collected using onboard and high-speed video cameras are used to examine gross morphing of the wing planform by the flight muscles, and smaller-scale morphing of the wing profile by aeroelastic deflection of the feathers, Carruthers et al. High-resolution still images are used to reconstruct the shape of the wing using multi-station photogrammetry, and the performance of the measured wing profile is analysed using a panel code, Carruthers et al. In bringing these lines of research together, we examine the role of aeroelastic feather deflection, and show that the key to perching in birds lies not in high-lift aerodynamics, but in the way in which the wings and tail morph to allow the bird to transition quickly from a steady glide into a deep stall.

scholarly journals Executive Function and Sensory Processing in Dichotic Listening of Young Adults with Listening Difficulties

2021 ◽  
Vol 10 (18) ◽  
pp. 4255
Author(s):  
Aline Tocchini Pascoinelli ◽  
Eliane Schochat ◽  
Cristina Ferraz Borges Murphy
Keyword(s):  
Sensory Processing ◽  
Cognitive Deficits ◽  
Dichotic Listening ◽  
Digit Span ◽  
Control Group ◽  
Cognitive Component ◽  
Right Ear Advantage ◽  
Attention Demands ◽  
Main Factor

Previous studies have suggested that varying attention demands in dichotic listening (DL) tasks might be a clinically feasible method to distinguish ‘bottom-up’ from ‘top-down’ deficits in listening. This study aims to investigate DL processing in adults with listening difficulties (LD). We assessed the performance of a listening difficulties group (LDG) (n = 24, mean age = 24, backward digit span = 4.0) and a control group (CG) (n = 25, mean age = 29.2, backward digit span = 6.4) in DL tests involving non-forced and both right and left-forced attention. The results indicated an overall significantly worse performance of LDG compared to the CG, which was greater for forced-left condition. This same result was observed when controlling for working memory (WM) variance. Both groups presented an overall right ear advantage with no difference in terms of the magnitude of advantage. These results indicate that LD presented by the LDG might be due to a combination of sensory and cognitive deficits, with emphasis on the cognitive component. However, the WM, although impaired in the LDG group, was not the main factor in segregating both groups. The role of the additional cognitive processes such as inhibitory control in LD is discussed.

scholarly journals Разрушение алюминий-магниевого сплава при воздействии импульсного лазерного излучения в условиях ползучести

2018 ◽  
Vol 60 (11) ◽  
pp. 2240
Author(s):  
А.А. Шибков ◽  
А.Е. Золотов ◽  
М.Ф. Гасанов ◽  
М.А. Желтов ◽  
К.А. Проскуряков ◽  
...  
Keyword(s):  
Tensile Testing ◽  
Main Crack ◽  
High Speed ◽  
Video Recording ◽  
Uniaxial Tensile ◽  
High Speed Video ◽  
Deformation Jump ◽  
Uniaxial Tensile Testing ◽  
Aluminum Magnesium Alloy

Abstract —Using high-speed video recording, the stages of predestruction and development of a main crack initiated by pulsed infrared laser radiation on the surface of the AlMg6 aluminum–magnesium alloy deformed by the uniaxial tensile testing under creep conditions are studied. The role of macroscopic bands of plastic strain in the development of the last deformation jump with an amplitude of about 10%, and the generation and propagation of the main crack is revealed. A possible mechanism of fracture is discussed.

scholarly journals Flagellar kinematics reveals the role of environment in shaping sperm motility

2020 ◽  
Vol 17 (170) ◽  
pp. 20200525
Author(s):  
Jeffrey S. Guasto ◽  
Jonathan B. Estrada ◽  
Filippo Menolascina ◽  
Lisa J. Burton ◽  
Mohak Patel ◽  
...  
Keyword(s):  
Sperm Motility ◽  
High Speed ◽  
Genetic Relatedness ◽  
Marine Invertebrates ◽  
Selective Pressure ◽  
Genetic Studies ◽  
New Approach ◽  
High Speed Video ◽  
Fluid Environment

Swimming spermatozoa from diverse organisms often have very similar morphologies, yet different motilities as a result of differences in the flagellar waveforms used for propulsion. The origin of these differences has remained largely unknown. Using high-speed video microscopy and mathematical analysis of flagellar shape dynamics, we quantitatively compare sperm flagellar waveforms from marine invertebrates to humans by means of a novel phylokinematic tree. This new approach revealed that genetically dissimilar sperm can exhibit strikingly similar flagellar waveforms and identifies two dominant flagellar waveforms among the deuterostomes studied here, corresponding to internal and external fertilizers. The phylokinematic tree shows marked discordance from the phylogenetic tree, indicating that physical properties of the fluid environment, more than genetic relatedness, act as an important selective pressure in shaping the evolution of sperm motility. More broadly, this work provides a physical axis to complement morphological and genetic studies to understand evolutionary relationships.

scholarly journals Spotted lanternfly nymphs use multiple righting behaviors during landing

2021 ◽  
Author(s):  
Suzanne Amador Kane ◽  
Theodore Bien ◽  
Luis Contreras-Orendain ◽  
Michael F. Ochs ◽  
S. Tonia Hsieh
Keyword(s):  
High Speed ◽  
Host Plants ◽  
Insect Pests ◽  
Abiotic Factors ◽  
High Speed Video ◽  
Lycorma Delicatula ◽  
Post Impact ◽  
Starvation And Desiccation ◽  
Summary Statement ◽  
And Control

AbstractMany small animals use aerial righting to mitigate the risks associated with falling, such as predation, starvation, and desiccation. Spotted lanternflies (Lycorma delicatula) (SLFs) are invasive insect pests that often fall from host plants in response to predators or abiotic factors (e.g., wind). We used high-speed video to study whether immature SLFs (nymphs) impact surfaces, and subsequently land upright, more often than expected by chance, and, if so, whether they do so via active or passive mechanisms. SLF nymphs were found to adopt a stereotypical falling posture proposed to promote passive righting, and similar to those assumed by falling insects, spiders, geckos, frogs and skydivers. Live SLF nymphs landed upright in more trials when releasing voluntarily (100%) or when dropped from tweezers (56%) than did dead specimens (33-35%), with differences being highly statistically significant, even when the dead specimens were posed in the falling posture. These results support a role for active aerial righting. The fraction landing upright also did not depend significantly either on orientation during release or at first impact. We found that significantly more live SLFs reoriented to upright after impacting in a non-upright orientation via bouncing in combination with adhering to the substrate with one or more feet. Videos of nymphs landing on leaves confirmed that these insects can use similar tactics to land upright on host plants. These findings indicate the important role post-impact righting plays in determining final orientation, and highlight the importance of studies that include ecologically-relevant substrates and naturalistic conditions.Summary statementHigh-speed video revealed the unexpected complexity of landing behaviors used by highly-invasive spotted lanternfly nymphs, providing new insights into a key step in understanding their dispersal and control.

Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

2006 ◽  
Vol 76 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Yukari Egashira ◽  
Shin Nagaki ◽  
Hiroo Sanada
Keyword(s):  
Body Weight ◽  
Urinary Excretion ◽  
Enzyme Activities ◽  
Treated Group ◽  
Control Group ◽  
Puromycin Aminonucleoside ◽  
Low Level ◽  
Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster

Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin
Keyword(s):  
Dna Sequences ◽  
Cell Types ◽  
Transcription Terminator ◽  
Response Elements ◽  
Polycomb Response Elements ◽  
The Individual ◽  
Multicellular Organisms ◽  
Different Cell Types ◽  
Main Factor

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

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