A Pacific Ocean general circulation model for satellite data assimilation

A tropical Pacific Ocean General Circulation Model (OGCM) to be used in satellite data assimilation studies is described. The transfer of the OGCM from a CYBER-205 at NOAA's Geophysical Fluid Dynamics Laboratory to a CRAY-2 at NASA's Ames Research Center is documented. Two 3-year model integrations from identical initial conditions but performed on those two computers are compared. The model simulations are very similar to each other, as expected, but the simulations performed with the higher-precision CRAY-2 is smoother than that with the lower-precision CYBER-205. The CYBER-205 and CRAY-2 use 32 and 64-bit mantissa arithmetic, respectively. The major features of the oceanic circulation in the tropical Pacific, namely the North Equatorial Current, the North Equatorial Countercurrent, the South Equatorial Current, and the Equatorial Undercurrent, are realistically produced and their seasonal cycles are described. The OGCM provides a powerful tool for study of tropical oceans and for the assimilation of satellite altimetry data

Cs adsorption on Si(001) surface: ab initio study

First-principles calculations using density functional theory based on norm-conserving pseudopotentials have been performed to investigate the Cs adsorption on the Si(001) surface for 0.5 and 1 ML coverages. We found that the saturation coverage corresponds to 1 ML adsorption with two Cs atoms occupying the double layer model sites. While the 0.5 ML covered surface is of metallic nature, we found that 1 ML of Cs adsorption corresponds to saturation coverage and leads to a semiconducting surface. The results for the electronic behavior and surface work function suggest that adsorption of Cs takes place via polarized covalent bonding.Comment: 8 pages, 7 figure

Stem-Cell Properties of Human Corneal Keratocytes

Purpose: To determine the stem cell properties of human corneal stromal keratocytes when challenged in the chick embryonic environment. Methods: Stromal keratocytes isolated from human corneas were injected along cranial neural crest migratory pathways and in the periocular mesenchyme in chick embryos. Localization Migration of the injected cells stromal keratocytes was determined at various stages of development by immunohistochemistry using human cell-specific markers. Differentiation of the human keratocytes into other neural crest-derived tissues was determined by immunohistochemistry with tissue cell-specific markers. Results: Human keratocytes injected along cranial neural crest pathways proliferated and migrated ventrally adjacent to host neural crest cells. They contributed to numerous neural crest-derived tissues including cranial blood vessels, ocular tissues, and cardiac cushion tissue mesenchyme. Keratocytes injected into the periocular mesenchyme region contributed to the corneal stroma and endothelial layers. Conclusions: Adult human corneal stromal keratocytes exhibit stem cell characteristics. They can be induced to form cranial neural crest derivatives, including other anterior ocular structures, when grafted into an embryonic environment

Corneal Plasticity: Characterization of the Multipotentiality of Human Keratocytes

Purpose: To determine the cell properties of adult human corneal keratocytes when challenged in the chick embryonic environment. Methods: Cultured human keratocytes were injected along cranial neural crest migratory pathways in chick embryos. Human keratocytes were also cultured under various conditions and differentiated into either fibroblasts or myofibroblasts, then transplanted into the chick embryo. Migration of the injected cells was determined by immunohistochemistry using human cell-specific markers and markers of crest derivatives. Results: Injected human keratocytes proliferated and migrated ventrally adjacent to host neural crest cells. They contributed to numerous neural crest-derived tissues including cranial blood vessels, ocular tissues, musculature of the mandibular process, and cardiac cushion tissue. Conclusions: Adult human corneal keratocytes that have undergone terminal differentiation can be induced to form cranial neural crest derivatives when grafted into an embryonic environment

Regularizing effect and local existence for non-cutoff Boltzmann equation

The Boltzmann equation without Grad's angular cutoff assumption is believed to have regularizing effect on the solution because of the non-integrable angular singularity of the cross-section. However, even though so far this has been justified satisfactorily for the spatially homogeneous Boltzmann equation, it is still basically unsolved for the spatially inhomogeneous Boltzmann equation. In this paper, by sharpening the coercivity and upper bound estimates for the collision operator, establishing the hypo-ellipticity of the Boltzmann operator based on a generalized version of the uncertainty principle, and analyzing the commutators between the collision operator and some weighted pseudo differential operators, we prove the regularizing effect in all (time, space and velocity) variables on solutions when some mild regularity is imposed on these solutions. For completeness, we also show that when the initial data has this mild regularity and Maxwellian type decay in velocity variable, there exists a unique local solution with the same regularity, so that this solution enjoys the $C^\infty$ regularity for positive time

Well-posedness of the Viscous Boussinesq System in Besov Spaces of Negative Order Near Index s=−1s=-1

This paper is concerned with well-posedness of the Boussinesq system. We prove that the $n$ ($n\ge2$) dimensional Boussinesq system is well-psoed for small initial data $(\vec{u}_0,\theta_0)$ ($\nabla\cdot\vec{u}_0=0$) either in $({B}^{-1}_{\infty,1}\cap{B^{-1,1}_{\infty,\infty}})\times{B}^{-1}_{p,r}$ or in ${B^{-1,1}_{\infty,\infty}}\times{B}^{-1,\epsilon}_{p,\infty}$ if $r\in[1,\infty]$, $\epsilon>0$ and $p\in(\frac{n}{2},\infty)$, where $B^{s,\epsilon}_{p,q}$ ($s\in\mathbb{R}$, $1\leq p,q\leq\infty$, $\epsilon>0$) is the logarithmically modified Besov space to the standard Besov space $B^{s}_{p,q}$. We also prove that this system is well-posed for small initial data in $({B}^{-1}_{\infty,1}\cap{B^{-1,1}_{\infty,\infty}})\times({B}^{-1}_{\frac{n}{2},1}\cap{B^{-1,1}_{\frac{n}{2},\infty}})$.Comment: 18 page