9,959 research outputs found
Adaptations in cardiac structure and function following high intensity interval training in a physically inactive population
Purpose:
Physical inactivity is associated with increased risk of cardiovascular disease and myocardial dysfunction. High intensity interval training (HIIT) has been shown to improve cardiovascular health; however, adaptations of cardiac structure and function are uncertain. Therefore, the aim of the present study was to analyse cardiac structural and functional adaptations to a HIIT protocol.
Methods:
Forty-one physically inactive individuals (males n=20 and females n=21) were randomised into either a 4-week HIIT intervention or control group. The HIIT consisted of 3 x 30-second maximal cycle ergometer sprints against a resistance of 7.5% body weight, separated by 2-minute active recovery periods. In total, 12-sessions were performed. All cardiac structural and functional parameters were measured by quantitative 2D transthoracic echocardiography, performed using a commercially available, portable ultrasound system (Vividâq, GE Healthcare, Milwaukee, Wisconsin) with a 1.5â3.6 MHz phased array transducer (M4SâRS Matrix cardiac ultrasound probe).
Results:
The HIIT intervention produced significant improvements in resting heart rate (65.59 ± 10.15 to 63.05 ± 13.42 b·min-1, P=0.013), stroke volume (55.48 ± 16.27 to 64.24 ± 20.62ml, P=0.015), left ventricular end diastolic volume (115.59 ± 28.34 to 131.94 ± 33.40ml, P=0.025), E/a ratio (1.98 ± 0.48 to 1.95 ± 0.55; P=0.027), average E/eâ ratio (5.41 ± 1.17 to 5.22 ± 0.89; P=0.002) and isovolumetric relaxation time (81.23 ± 12.85 to 77.83 ± 9.81 m·s-1; P=0.022) compared to the control group.
Conclusion:
HIIT produced significant improvements in resting haemodynamics and diastolic function. This time efficient exercise intervention produces important improvements in myocardial function in a physically inactive population, which may be of clinical importance in higher risk populations
Crustal fault reactivation facilitating lithospheric folding/buckling in the central Indian Ocean
High-quality, normal-incidence seismic reflection data confirm that tectonic deformation in the central Indian Ocean occurs at two spatial scales: whole lithosphere folding with wavelengths varying between 100 and 300 km, and compressional reactivation of crustal faults with a characteristic spacing of c. 5 km. Faults penetrate through the crust and probably into the upper mantle. Both types of deformation are driven by regional large intraplate stresses originating from the Indo-Eurasian collision. Numerical modelling of the spatial and temporal relationships between these two modes of deformations shows that, in agreement with geophysical observations, crustal faults are reactivated first with stick-slip behaviour. Subsequent lithospheric folding does not start until horizontal loading has significantly reduced the mechanical strength of the lithosphere, as predicted by elasto-plastic buckling theory. Modelling suggests that lithospheric folding does not develop in the absence of fault reactivation. Crustal fault reactivation, therefore, appears to be a key facilitating mechanism for oceanic lithospheric buckling in the central Indian Ocean
The preservation of quartz grain surface textures following vehicle fire and their use in forensic enquiry
During a terrorist trial, dispute arose as to whether the temperature produced in a car fire was sufficient to destroy quartz grain surface textures. A series of seven sequential experiments showed that the temperature for quartz surface texture modification/destruction and the production of vugs, vesicles and glassy precipitation ('snowdrifting') occurred at 1200 degrees C under normal atmospheric conditions. By adding a number of man-made and natural substances, it was found that only the presence of salts depressed this modification temperature (to 900 degrees C). Experiments to determine the temperature of fire in a car indicated that the maximum temperature produced under natural conditions (810 degrees C) was insufficient to affect the quartz grain Surface textures. These results confirm the use of surface texture analysis of quartz grains recovered from the remains of cars Subjected to fire and their use as a forensic indicator. (C) 2008 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved
Current status of MCNP6 as a simulation tool useful for space and accelerator applications
For the past several years, a major effort has been undertaken at Los Alamos
National Laboratory (LANL) to develop the transport code MCNP6, the latest LANL
Monte-Carlo transport code representing a merger and improvement of MCNP5 and
MCNPX. We emphasize a description of the latest developments of MCNP6 at higher
energies to improve its reliability in calculating rare-isotope production,
high-energy cumulative particle production, and a gamut of reactions important
for space-radiation shielding, cosmic-ray propagation, and accelerator
applications. We present several examples of validation and verification of
MCNP6 compared to a wide variety of intermediate- and high-energy experimental
data on reactions induced by photons, mesons, nucleons, and nuclei at energies
from tens of MeV to about 1 TeV/nucleon, and compare to results from other
modern simulation tools.Comment: 4 pages, 3 figures, Proc. 11th Conference on the Intersections of
Particle and Nuclear Physics (CIPANP 2012), St. Petersburg, FL, May 28 - June
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The range of axial rotation of the glenohumeral joint.
Accepted versio
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