4,161 research outputs found
Optimal Curvature Decays on Asymptotically Locally Euclidean Manifolds
We present a method in nonlinear elliptic systems to study curvature decays
on asymptotically locally Euclidean (ALE) manifolds. In particular, we show
that scalar flat Kahler and harmonic ALE metrics of real dimension n are of
order n-2.Comment: 28 page
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Comparative Study of Xenobiotic-Free Media for the Cultivation of Human Limbal Epithelial Stem/Progenitor Cells.
The culture of human limbal epithelial stem/progenitor cells (LSCs) in the presence of animal components poses the risk of cross-species contamination in clinical applications. We quantitatively compared different xenobiotic-free culture media for the cultivation of human LSCs. LSCs were cultured from 2 × 2 mm limbal tissue explants on denuded human amniotic membrane with different xenobiotic-free culture media: CnT-Prime (CnT-PR) supplemented with 0%, 1%, 5%, and 10% human serum (HS), embryonic stem cell medium (ESCM) alone or in combination with the standard supplemented hormonal epithelium medium (SHEM, control) at a 1:1 dilution ratio, and modified SHEM (mSHEM), in which cholera toxin and dimethyl sulfoxide (DMSO) were removed, isoproterenol was added, and the epidermal growth factor concentration was reduced. Several parameters were quantified to assess the LSC phenotype: cell morphology, cell growth, cell size, outgrowth size, and expression of the undifferentiated LSC markers cytokeratin (K) 14, and p63α high-expressing (p63αbright) cells, a mature keratinocyte marker K12, epithelial marker pancytokeratin (PanK), and stromal cell marker vimentin (Vim). Compared with the standard SHEM control, CnT-PR base medium was associated with a lower cell growth and reduction in the proportion of stem cells generated regardless of the amount of HS supplemented (p < 0.05); ESCM resulted in an increased proportion of PanK-/Vim+ stromal cells (p < 0.05) and a decreased proportion of p63αbright cells (p < 0.05); mSHEM supported a similar cell growth (p > 0.05), increased the number of small cells (diameter ≤12 μm; p < 0.05), and provided a similar proportion of p63αbright cells (p > 0.05). Among all the conditions tested, mSHEM was the most efficient and consistent in supporting the LSC phenotype and growth
Endothelium in the pharyngeal arches 3, 4 and 6 is derived from the second heart field.
Oxygenated blood from the heart is directed into the systemic circulation through the aortic arch arteries (AAAs). The AAAs arise by remodeling of three symmetrical pairs of pharyngeal arch arteries (PAAs), which connect the heart with the paired dorsal aortae at mid-gestation. Aberrant PAA formation results in defects frequently observed in patients with lethal congenital heart disease. How the PAAs form in mammals is not understood. The work presented in this manuscript shows that the second heart field (SHF) is the major source of progenitors giving rise to the endothelium of the pharyngeal arches 3 - 6, while the endothelium in the pharyngeal arches 1 and 2 is derived from a different source. During the formation of the PAAs 3 - 6, endothelial progenitors in the SHF extend cellular processes toward the pharyngeal endoderm, migrate from the SHF and assemble into a uniform vascular plexus. This plexus then undergoes remodeling, whereby plexus endothelial cells coalesce into a large PAA in each pharyngeal arch. Taken together, our studies establish a platform for investigating cellular and molecular mechanisms regulating PAA formation and alterations that lead to disease
Low cost strategies to build dynamic capabilities: The creative approach of a French public transport operator
International audienceDynamic capabilities have been discussed as a way to achieve competitive advantage. However, research on the building of dynamic capabilities is still scarce. This article tackles the issue of potential federative guidance to manage this building and illustrates it through the low cost approach adopted by a public transport operator. Resulting of an oriented creativity method combined with the use of two divergent strategies of low cost product development, the company was able to make several improvements that contributed to build dynamic capabilities at both firm and industrial ecosystem levels: (1) reviewed its managerial system, making transversal projects that were previously hard to be launched; (2) increased its absorptive capability and quality of interaction with ecosystem's stakeholders, better targeting and acquiring external knowledge through collaborative explorations; and (3) dealt with the external barriers and core-rigidities at both firm and industrial ecosystem levels through two different and complementary ways of developing low-cost offer for public transport. Thus, low cost approach appears as an eligible federative guidance to build dynamic capability, similar investigation could benefit to other firms
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