1,230 research outputs found
Hydraulic forces caused by annular pressure seals in centrifugal pumps
The hydraulic forces caused by annular pressure seals were investigated. The measured inlet and exit loss coefficients of the flow through the seals were much smaller than the conventional values. The results indicate that the damping coefficient and the inertia coefficient of the fluid film in the seal are not affected much by the rotational speed or the eccentricity of the rotor, though the stiffness coefficient seemed to be influenced by the eccentricity
RELIABILITY OF INVERSE DYNAMICS OF THE WHOLE BODY IN THE TENNIS FOREHAND
Reliability of joint moment calculation using inverse dynamics is critical for evaluation of joint function and has been investigated for locomotion and lifting tasks, but not for sport movements in which the trunk can not be assumed to be rigid. The tennis forehand was studied in this paper because many biomechanical studies on the movement have been performed (Elliott et al., 1989) and the trunk twists substantially in the forehand. The purpose of this study was to investigate the reliability of the inverse dynamic analysis of the whole body in a tennis forehand using different segment inertial parameter (SIP) sets
INFLUENCES OF THE MASS OF BOXING GLOVES ON THE IMPACT FORCE OF A REAR HAND STRAIGHT PUNCH
The purpose of this paper was to investigate the influences of the mass of boxing gloves on the impact force of a rear hand straight punch thrown into an unfixed target whose mass (4.36kg) was similar to that of the typical human head
Chondroprotective effects of Salubrinal in a mouse model of osteoarthritis
OBJECTIVES:
Salubrinal is a synthetic agent that elevates phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) and alleviates stress to the endoplasmic reticulum. Previously, we reported that in chondrocytes, Salubrinal attenuates expression and activity of matrix metalloproteinase 13 (MMP13) through downregulating nuclear factor kappa B (NFκB) signalling. We herein examine whether Salubrinal prevents the degradation of articular cartilage in a mouse model of osteoarthritis (OA).
METHODS:
OA was surgically induced in the left knee of female mice. Animal groups included age-matched sham control, OA placebo, and OA treated with Salubrinal or Guanabenz. Three weeks after the induction of OA, immunoblotting was performed for NFκB p65 and p-NFκB p65. At three and six weeks, the femora and tibiae were isolated and the sagittal sections were stained with Safranin O.
RESULTS:
Salubrinal suppressed the progression of OA by downregulating p-NFκB p65 and MMP13. Although Guanabenz elevates the phosphorylation level of eIF2α, it did not suppress the progression of OA.
CONCLUSIONS:
Administration of Salubrinal has chondroprotective effects in arthritic joints. Salubrinal can be considered as a potential therapeutic agent for alleviating symptoms of OA. Cite this article: Bone Joint Res 2015;4:84-92
Gauge Theory Description of Spin Ladders
A s=1/2 antiferromagnetic spin chain is equivalent to the two-flavor massless
Schwinger model in an uniform background charge density in the strong coupling.
The gapless mode of the spin chain is represented by a massless boson of the
Schwinger model. In a two-leg spin ladder system the massless boson aquires a
finite mass due to inter-chain interactions. The gap energy is found to be
about .25 k |J'| when the inter-chain Heisenberg coupling J' is small compared
with the intra-chain Heisenberg coupling. k is a constant of O(1). It is also
shown that a cyclically symmetric N-leg ladder system is gapless or gapful for
an odd or even N, respectively.Comment: 8 pages. CORRIGENDUM has been incorporated. (A factor 2 error has
been corrected.
Arginase from kiwifruit: properties and seasonal variation
The in vitro activity of arginase (EC 3.5.3.1) was investigated in youngest-mature leaves and roots (1-3 mm diameter) of kiwifruit vines (Actinidia deliciosa var. deliciosa) during an annual growth cycle, and enzyme from root material partially purified. No seasonal trend in the specific activity of arginase was observed in roots. Measurements in leaves, however, rose gradually during early growth and plateaued c. 17 weeks after budbreak. Changes in arginase activity were not correlated with changes in the concentration of arginine (substrate) or glutamine (likely end-product of arginine catabolism) in either tissue during the growth cycle. Purification was by (NH4)2SO4 precipitation and DEAE-cellulose chromatography. The kinetic properties of the enzyme, purified 60-fold over that in crude extracts, indicated a pH optimum of 8.8, and a Km (L-arginine) of 7.85 mM. Partially-purified enzyme was deactivated by dialysis against EDTA, and reactivated in the presence of Mn²⁺, Co²⁺, and Ni²⁺
Mixed-Spin Ladders and Plaquette Spin Chains
We investigate low-energy properties of a generalized spin ladder model with
both of the spin alternation and the bond alternation, which allows us to
systematically study not only ladder systems but also alternating spin chains.
By exploiting non-linear model techniques we study the model with
particular emphasis on the competition between gapful and gapless states. Our
approach turns out to provide a more consistent semi-classical description of
alternating spin chains than that in the previous work. We also study a closely
related model, i.e., a spin chain with plaquette structure, and show that
frustration causes little effect on its low-energy properties so far as the
strength of frustration is weaker than a certain critical value.Comment: 7 pages, REVTeX, 3 figures, submitted to JPS
The free surface of superfluid 4He at zero temperature
The structure and energetics of the free surface of superfluid He are
studied using the diffusion Monte Carlo method. Extending a previous
calculation by Vall\'es and Schmidt, which used the Green's function Monte
Carlo method, we study the surface of liquid He within a slab geometry
using a larger number of particles in the slab and an updated interatomic
potential. The surface tension is accurately estimated from the energy of slabs
of increasing surface density and its value is close to one of the two existing
experimental values. Results for the density profiles allow for the calculation
of the surface width which shows an overall agreement with recent experimental
data. The dependence on the transverse direction to the surface of other
properties such as the two-body radial distribution function, structure factor,
and one-body density matrix is also studied. The condensate fraction, extracted
from the asymptotic behavior of the one-body density matrix, shows an
unambiguous enhancement when approaching the surface.Comment: RevTex, 11 pages, accepted in Phys. Rev.
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