8,184 research outputs found
Vacuum-stripped silicone binder for thermal-control paint
Silicone elastomer is placed in evacuating system, heated to 160 C and held at this temperature for 24 hours. Elastomer is then cooled to room temperature in vacuum, producing upgraded, low outgassing polymer of increased molecular weight
The behavior of several white pigments as determined by in situ reflectance measurements of irradiated specimens
Reflectance measurements of irradiated specimens of zinc oxide and zinc orthotitanate white pigment material
Development of space stable thermal control coatings Triannual report, Mar. 1 - Jul. 31, 1967
Ultraviolet irradiation effects on space stable thermal control zinc coating
Global turbulence simulations of the tokamak edge region with GRILLIX
Turbulent dynamics in the scrape-off layer (SOL) of magnetic fusion devices
is intermittent with large fluctuations in density and pressure. Therefore, a
model is required that allows perturbations of similar or even larger magnitude
to the time-averaged background value. The fluid-turbulence code GRILLIX is
extended to such a global model, which consistently accounts for large
variation in plasma parameters. Derived from the drift reduced Braginskii
equations, the new GRILLIX model includes electromagnetic and electron-thermal
dynamics, retains global parametric dependencies and the Boussinesq
approximation is not applied. The penalisation technique is combined with the
flux-coordinate independent (FCI) approach [F. Hariri and M. Ottaviani,
Comput.Phys.Commun. 184:2419, (2013); A. Stegmeir et al., Comput.Phys.Commun.
198:139, (2016)], which allows to study realistic diverted geometries with
X-point(s) and general boundary contours. We characterise results from
turbulence simulations and investigate the effect of geometry by comparing
simulations in circular geometry with toroidal limiter against realistic
diverted geometry at otherwise comparable parameters. Turbulence is found to be
intermittent with relative fluctuation levels of up to 40% showing that a
global description is indeed important. At the same time via direct comparison,
we find that the Boussinesq approximation has only a small quantitative impact
in a turbulent environment. In comparison to circular geometry the fluctuations
are reduced in diverted geometry, which is related to a different zonal flow
structure. Moreover, the fluctuation level has a more complex spatial
distribution in diverted geometry. Due to local magnetic shear, which differs
fundamentally in circular and diverted geometry, turbulent structures become
strongly distorted in the perpendicular direction and are eventually damped
away towards the X-point
The Polyakov action on the supertorus
A consistent method for obtaining a well-defined Polyakov action on the
supertorus is presented. This method uses the covariantization of derivative
operators and enables us to construct a Polyakov action which is globally
defined.Comment: 15 pages LaTe
Basics of factorization in a scalar Yukawa field theory
The factorization theorems of quantum chromodynamics (QCD) apply equally well
to most simple quantum field theories that require renormalization but where
direct calculations are much more straightforward. Working with these simpler
theories is convenient for stress-testing the limits of the factorization
program and for examining general properties of the parton density functions
(pdfs) or other correlation functions that might be necessary for a factorized
description of a process. With this view in mind, we review the steps of
factorization in a real scalar Yukawa field theory for both deep inelastic
scattering (DIS) and semi-inclusive deep inelastic scattering (SIDIS) cross
sections. In the case of SIDIS, we illustrate how to separate the small
transverse momentum region, where transverse momentum dependent (TMD) pdfs are
needed, from a purely collinear large transverse momentum region, and we
examine the influence of subleading power corrections. We also review the steps
for formulating TMD factorization in transverse coordinate space, and we study
the effect of transforming to the well-known -scheme. Within the Yukawa
theory, we investigate the consequences of switching to a generalized parton
model (GPM) approach, and compare with a fully factorized approach. Our results
highlight the need to address similar or analogous issues in QCD.Comment: 39 pages, 46 figure
Thermo-statistical description of gas mixtures from space partitions
The new mathematical framework based on the free energy of pure classical
fluids presented in [R. D. Rohrmann, Physica A 347, 221 (2005)] is extended to
multi-component systems to determine thermodynamic and structural properties of
chemically complex fluids. Presently, the theory focuses on -dimensional
mixtures in the low-density limit (packing factor ). The formalism
combines the free-energy minimization technique with space partitions that
assign an available volume to each particle. is related to the
closeness of the nearest neighbor and provides an useful tool to evaluate the
perturbations experimented by particles in a fluid. The theory shows a close
relationship between statistical geometry and statistical mechanics. New,
unconventional thermodynamic variables and mathematical identities are derived
as a result of the space division. Thermodynamic potentials ,
conjugate variable of the populations of particles class with the
nearest neighbors of class are defined and their relationships with the
usual chemical potentials are established. Systems of hard spheres are
treated as illustrative examples and their thermodynamics functions are derived
analytically. The low-density expressions obtained agree nicely with those of
scaled-particle theory and Percus-Yevick approximation. Several pair
distribution functions are introduced and evaluated. Analytical expressions are
also presented for hard spheres with attractive forces due to K\^ac-tails and
square-well potentials. Finally, we derive general chemical equilibrium
conditions.Comment: 14 pages, 8 figures. Accepted for publication in Physical Review
Adopters of new farm ideas : characteristics and communications behavior (1961)
"IP-15M-10:61-SQ.""Agricultural Extension Services of Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin.""North central regional extension publication number 13.""Farm Foundation and Federal Extension Service Cooperating.""Subcommittee for the study of diffusion of farm practices.
Plasmodium falciparum ligand binding to erythrocytes induce alterations in deformability essential for invasion
The most lethal form of malaria in humans is caused by Plasmodium falciparum. These parasites invade erythrocytes, a complex process involving multiple ligand-receptor interactions. The parasite makes initial contact with the erythrocyte followed by dramatic deformations linked to the function of the Erythrocyte binding antigen family and P. falciparum reticulocyte binding-like families. We show EBA-175 mediates substantial changes in the deformability of erythrocytes by binding to glycophorin A and activating a phosphorylation cascade that includes erythrocyte cytoskeletal proteins resulting in changes in the viscoelastic properties of the host cell. TRPM7 kinase inhibitors FTY720 and waixenicin A block the changes in the deformability of erythrocytes and inhibit merozoite invasion by directly inhibiting the phosphorylation cascade. Therefore, binding of P. falciparum parasites to the erythrocyte directly activate a signaling pathway through a phosphorylation cascade and this alters the viscoelastic properties of the host membrane conditioning it for successful invasion
Multi loop soliton solutions and their interactions in the Degasperis-Procesi equation
In this article, we construct loop soliton solutions and mixed soliton - loop
soliton solution for the Degasperis-Procesi equation. To explore these
solutions we adopt the procedure given by Matsuno. By appropriately modifying
the -function given in the above paper we derive these solutions. We
present the explicit form of one and two loop soliton solutions and mixed
soliton - loop soliton solutions and investigate the interaction between (i)
two loop soliton solutions in different parametric regimes and (ii) a loop
soliton with a conventional soliton in detail.Comment: Published in Physica Scripta (2012
- …