3,065 research outputs found
Moment-Fourier approach to ion parallel fluid closures and transport for a toroidally confined plasma
A general method of solving the drift kinetic equation is developed for an
axisymmetric magnetic field. Expanding a distribution function in general
moments a set of ordinary differential equations are obtained. Successively
expanding the moments and magnetic-field involved quantities in Fourier series,
a set of linear algebraic equations is obtained. The set of full (Maxwellian
and non-Maxwellian) moment equations is solved to express the density,
temperature, and flow velocity perturbations in terms of radial gradients of
equilibrium pressure and temperature. Closure relations that connect parallel
heat flux density and viscosity to the radial gradients and parallel gradients
of temperature and flow velocity, are also obtained by solving the
non-Maxwellian moment equations. The closure relations combined with the
linearized fluid equations reproduce the same solution obtained directly from
the full moment equations. The method can be generalized to derive closures and
transport for an electron-ion plasma and a multi-ion plasma in a general
magnetic field.Comment: 25 pages, 9 figure
Electron Parallel Transport for Arbitrary Collisionality
Integral (nonlocal) closures [J.-Y. Ji and E. D. Held, Phys. Plasmas 21, 122116 (2014)] are combined with the momentum balance equation to derive electron parallel transport relations. For a single harmonic fluctuation, the relations take the same form as the classical Spitzer theory (with possible additional terms): the electric current and heat flux densities are connected to the modified electric field and temperature gradient by transport coefficients. In contrast to the classical theory, the dimensionless coefficients depend on the collisionality quantified by a Knudsen number, the ratio of the collision length to the angular wavelength. The key difference comes from the proper treatment of the viscosity and friction terms in the momentum balance equation, accurately reflecting the free streaming and collision terms in the kinetic equation. For an arbitrary fluctuation, the transport relations may be expressed by a Fourier series or transform. For low collisionality, the electric resistivity can be significantly larger than that of classical theory and may predict the correct timescale for fast magnetic reconnection
Electron Parallel Closures for Various Ion Charge Numbers
Electron parallel closures for the ion charge number Z = 1 [J.-Y. Ji and E. D. Held, Phys. Plasmas 21, 122116 (2014)] are extended for 1 ≤ Z ≤ 10. Parameters are computed for various Z with the same form of the Z = 1 kernels adopted. The parameters are smoothly varying in Z and hence can be used to interpolate parameters and closures for noninteger, effective ion charge numbers
Activation of spleen tyrosine kinase is required for TNF-α-induced endothelin-1 upregulation in human aortic endothelial cells
AbstractEndothelin-1 (ET-1) promotes atherosclerosis. We tested whether spleen tyrosine kinase (Syk) mediates tumor necrosis factor-α (TNF-α)-induced ET-1 upregulation in human aortic endothelial cells (HAECs) and sought to identify the signal pathways involved. TNF-α-induced reactive oxygen species (ROS) activated Syk and phosphatidylinositol 3-kinase (PI3K), which was required for the activation of AP-1 and subsequent ET-1 gene transcription. ROS mediated c-Jun NH2-terminal kinase (JNK) is also required for AP-1 activation, but Syk and PI3K regulated AP-1 activation independently of JNK. Through regulation of ET-1 production, Syk could be implicated in atherosclerosis
Molecular environment and thermal X-ray spectroscopy of the semicircular young composite supernova remnant 3C 396
We have investigated the molecular environment of the semicircular composite
supernova remnant (SNR) 3C396 and performed a Chandra spatially resolved
thermal X-ray spectroscopic study of this young SNR. With our CO millimeter
observations, we find that the molecular clouds (MCs) at V(LSR)~84km/s can
better explain the multiwavelength properties of the remnant than the
V(LSR)=67-72km/s MCs that are suggested by Lee et al. (2009). At around 84km/s,
the western boundary of the SNR is perfectly confined by the western molecular
wall. The CO emission fades out from west to east, indicating that the eastern
region is of low gas density. In particular, an intruding finger/pillar-like
MC, which may be shocked at the tip, can well explain the X-ray and radio
enhancement in the southwest and some infrared filaments there. The SNR-MC
interaction is also favored by the relatively elevated 12CO J=2-1/J=1-0 line
ratios in the southwestern "pillar tip" and the molecular patch on the
northwestern boundary. The redshifted 12CO (J=1-0 and J=2-1) wings (86-90km/s)
of an eastern 81km/s molecular patch may be the kinematic evidence for shock-MC
interaction. We suggest that the 69km/s MCs are in the foreground based on HI
self-absorption while the 84km/s MCs at a distance of 6.2 kpc (the tangent
point) are in physical contact with SNR 3C396. The X-ray spectral analysis
suggests an SNR age of ~3kyr. The metal enrichment of the X-ray emitting gas in
the north and south implies a 13-15Msun B1-B2 progenitor star.Comment: 17 amulateapj pages, including 11 figures and 3 tables. Accepted to
ApJ. Version 2: minor correction
Suitable dietary protein/lipid of hybrid, female red sea bream Pagrus major and Male Black Sea Bream Acanthopagrus schlegeli in Juvenile Stage, as compared with Red Sea Bream
To determine a suitable dietary protein/lipid (CP/CL) ratio in the early juvenile stages of hybrid porgy (F1), female red sea bream (RSB) × male black sea bream, five diets with various CP/CL ratios—60/7, 55/12, 51/17, 46/23, and 41/28—were prepared and provided to juveniles in triplicate. At the smaller juvenile stage, F1, weighing 0.32 g, a significantly higher specific growth rate (SGR) and feed efficiency (FE) were seen with 60/7 and 55/12 diets. However, in RSB weighing 0.26 g, SGR and FE were higher
with the 60/7 diet than the other diets at 21°C. At the larger juvenile stage, F1, weighing 3.7 g, there was no significant difference in SGR or FE among the diets, but RSB weighing 4.0 g fed 60/7, 55/12, and 51/17 diets had higher SGR and FE than 46/23 and 41/28 diets at 24°C. Moreover, survival and apparent nutrient retention of F1 at both stages were significantly higher than those in
RSB. These results indicate that both F1 and RSB weighing ca. 0.3 g require a higher dietary CP/CL than those weighing ca. 4 g. Additionally, F1 in both trials showed the suitability of a lower dietary CP/CL than RSB, indicating that mass production of F1 juveniles will be more economical than RSB
Phosphatidylcholine induces apoptosis of 3T3-L1 adipocytes
<p>Abstract</p> <p>Background</p> <p>Phosphatidylcholine (PPC) formulation is used for lipolytic injection, even though its mechanism of action is not well understood.</p> <p>Methods</p> <p>The viability of 3T3-L1 pre-adipocytes and differentiated 3T3-L1 cells was measured after treatment of PPC alone, its vehicle sodium deoxycholate (SD), and a PPC formulation. Western blot analysis was performed to examine PPC-induced signaling pathways.</p> <p>Results</p> <p>PPC, SD, and PPC formulation significantly decreased 3T3-L1 cell viability in a concentration-dependent manner. PPC alone was not cytotoxic to CCD-25Sk human fibroblasts at concentrations <1 mg/ml, whereas SD and PPC formulation were cytotoxic. Western blot analysis demonstrated that PPC alone led to the phosphorylation of the stress signaling proteins, such as p38 mitogen-activated protein kinase and c-Jun N-terminal kinase, and activated caspase-9, -8, -3 as well as cleavage of poly(ADP-ribose) polymerase. However, SD did not activate the apoptotic pathways. Instead, SD and PPC formulation induced cell membrane lysis, which may lead to necrosis of cells.</p> <p>Conclusions</p> <p>PPC results in apoptosis of 3T3-L1 cells.</p
- …