A Deficiency Problem of the Least Squares Finite Element Method for Solving Radiative Transfer in Strongly Inhomogeneous Media

The accuracy and stability of the least squares finite element method (LSFEM) and the Galerkin finite element method (GFEM) for solving radiative transfer in homogeneous and inhomogeneous media are studied theoretically via a frequency domain technique. The theoretical result confirms the traditional understanding of the superior stability of the LSFEM as compared to the GFEM. However, it is demonstrated numerically and proved theoretically that the LSFEM will suffer a deficiency problem for solving radiative transfer in media with strong inhomogeneity. This deficiency problem of the LSFEM will cause a severe accuracy degradation, which compromises too much of the performance of the LSFEM and makes it not a good choice to solve radiative transfer in strongly inhomogeneous media. It is also theoretically proved that the LSFEM is equivalent to a second order form of radiative transfer equation discretized by the central difference scheme

On the Derivation of Vector Radiative Transfer Equation for Polarized Radiative Transport in Graded Index Media

Light transport in graded index media follows a curved trajectory determined by the Fermat's principle. Besides the effect of variation of the refractive index on the transport of radiative intensity, the curved ray trajectory will induce geometrical effects on the transport of polarization ellipse. This paper presents a complete derivation of vector radiative transfer equation for polarized radiation transport in absorption, emission and scattering graded index media. The derivation is based on the analysis of the conserved quantities for polarized light transport along curved trajectory and a novel approach. The obtained transfer equation can be considered as a generalization of the classic vector radiative transfer equation that is only valid for uniform refractive index media. Several variant forms of the transport equation are also presented, which include the form for Stokes parameters defined with a fixed reference and the Eulerian forms in the ray coordinate and in several common orthogonal coordinate systems.Comment: This paper has been submitted to JQSR

Application of spherical harmonics analysis on LBS particles and LBS fragments

This paper applies surface parameterization and spherical harmonics analysis to the characterization of particle shapes of Leighton Buzzard sand (LBS) particles and LBS fragments obtained from X-ray micro-tomography (μCT). The rotation, transition and scale independent spherical coefficients were obtained. The relationship between spherical coefficients and shape parameters of form, roundness and compactness was investigated. The coefficients of degree one determine the principal dimensions of an ellipsoid, which has a similar aspect ratio with the original surface. The coefficients of higher degree characterise more details by increasing the percentage of higher and lower mean curvature on the reconstructed surface. As the spherical degree increases, the reconstructed surface tend to have lower particle roundness, sphericity and convexity, and higher aspect ratio

Tunnelling through black rings

Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton gravity theory is analyzed by use of the Parikh-Wilczek tunnelling method. To get the correct tunnelling amplitude and emission rate, we adopted and developed the Angheben-Nadalini-Vanzo-Zerbini covariant approach to cover the effects of rotation and electronic discharge all at once, and the effect of back reaction is also taken into account. This constitute a unified approach to the tunnelling problem. Provided the first law of thermodynamics for black rings holds, the emission rate is proportional to the exponential of the change of Bekenstein-Hawking entropy. Explicit calculation for black ring temperatures agree exactly with the results obtained via the classical surface gravity method and the quasilocal formalism.Comment: 10 pages, V2: various modifications throughout the text, plus a lot of newly added reference

Bound state solutions of the Dirac-Rosen-Morse potential with spin and pseudospin symmetry

The energy spectra and the corresponding two- component spinor wavefunctions of the Dirac equation for the Rosen-Morse potential with spin and pseudospin symmetry are obtained. The $s-$wave ($\kappa = 0$ state) solutions for this problem are obtained by using the basic concept of the supersymmetric quantum mechanics approach and function analysis (standard approach) in the calculations. Under the spin symmetry and pseudospin symmetry, the energy equation and the corresponding two-component spinor wavefunctions for this potential and other special types of this potential are obtained. Extension of this result to $\kappa \neq 0$ state is suggested.Comment: 18 page

Metamaterial Polarization Converter Analysis: Limits of Performance

In this paper we analyze the theoretical limits of a metamaterial converter that allows for linear-to- elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50%, while the realistic re ection configuration can give the conversion efficiency up to 90%. We show that a double layer transmission converter and a single layer with a ground plane can have 100% polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design for virtually any frequency range of the electromagnetic waves.Comment: 10 pages, 11 figures, 2 table

Caffeine Suppresses GABA Receptor-Mediated Current in Rat Primary Sensory Neurons Via Inhibition of Intracellular Phosphodiesterase

In acutely isolated rat primary sensory neurons, the effects of caffeine on GABA receptormediated current (IGABA) were investigated using a whole-cell patch clamp technique. We found that applications of GABA (10-1000 µM) induced inward currents in a concentration-dependent manner; the currents manifested obvious desensitization. Pretreatment with caffeine (0.01- 100 µM) suppressed IGABA in a noncompetitive manner; caffeine shifted the concentration – response curve for GABA downwards compared to the control. Theophylline showed a similar and stronger inhibitory effect on IGABA. Isolated application of 1 µM diazepam enhanced IGABA, while pretreatment with 10 µM caffeine and 1 µM diazepam suppressed this current. Intracellular application of the protein kinase A inhibitor H-8 dramatically weakened the inhibitory effect of caffeine on IGABA. Because primary afferent depolarization is related to GABAA receptors, our results suggest that caffeine might antagonize presynaptic inhibitory effects of primary afferents, probably via inhibition of intracellular phosphodiesterase.Досліджували впливи кофеїну на струми, опосередковані рецепторами ГАМК (IGABA), в гостроізольованих первинних нейронах щура; використовували методику петчклемп у конфігурації «ціла клітина». Аплікації ГАМК (10–1000 мкМ) викликали струми вхідного напрямку, амплітуда котрих була залежною від концентрації; струми демонстрували яскраво виражену десенситизацію. Попередня обробка кофеїном (0.01–100 мкМ) призводила до неконкурентного пригнічення IGABA. Вплив кофеїну зміщував вниз криву концентрація–відповідь для ГАМК порівняно з контролем. Теофілін демонстрував подібні й навіть сильніші гальмівні впливи на IGABA. Ізольована аплікація 1 мкМ діазепаму посилювала IGABA, тоді як попередня обробка 10 мкМ кофеїну перед дією 1 мкМ діазепаму пригнічувала цей струм. Внутрішньоклітинна аплікація H-8 (інгібітору протеїнкінази А) дуже значно послаблювала гальмівний вплив кофеїну на IGABA. Оскільки деполяризація терміналий первинних аферентів опосередковується рецепторами ГАМК, наші результати вказують на те, що кофеїн може протистояти пресинаптичному гальмуванню первинних аферентів. Ефекти кофеїну опосередковуються гальмуванням внутрішньоклітинної фосфодіестерази

Generic Rotation in a Collective SD Nucleon-Pair Subspace

Low-lying collective states involving many nucleons interacting by a random ensemble of two-body interactions (TBRE) are investigated in a collective SD-pair subspace, with the collective pairs defined dynamically from the two-nucleon system. It is found that in this truncated pair subspace collective vibrations arise naturally for a general TBRE hamiltonian whereas collective rotations do not. A hamiltonian restricted to include only a few randomly generated separable terms is able to produce collective rotational behavior, as long as it includes a reasonably strong quadrupole-quadrupole component. Similar results arise in the full shell model space. These results suggest that the structure of the hamiltonian is key to producing generic collective rotation.Comment: 11 pages, 5 figure

A study of the glazing techniques and provenances of Tang sancai glazes using elemental and lead isotope analyses

This study discusses the elemental compositions and lead isotope ratios of Tang sancai glazes unearthed from the Huangpu kiln, Huangye kiln and two Tang sancai tomb sites. The various glazes feature distinct lead isotope ratios and trace element characteristics, which can be interpreted as evidence for the use of different lead ore deposits and siliceous raw materials in the glazes. This is a strong indication that lead isotopes combined with trace element analysis could be used as a viable approach for identifying the provenance of Tang sancai of unknown origin by linking them to kiln sites, This provenance technique could be significant in the interpretation of ancient ceramic trade and communication patterns. In this study, the provenance of several Tang sancai glazes of uncertain origin were determined using this method: some Tang sancai wares unearthed in Xi'an City were produced in the kiln near Luoyang City and then traded to Xi'an City, providing an idea of ancient Tang sancai ceramic trade route