4,983 research outputs found
Dupin hypersurfaces in Lie sphere geometry
The method of moving frames in Lie sphere geometry has produced significant
results in the classification of Dupin hypersurfaces in spheres. What is the
secret of its effectiveness? The answer emerges in the classification of
nonumbilic isoparametric surfaces in the space form geometries. Using the
method of moving frames, the proof of this classification is an elementary
exercise. The same proof classifies the cyclides of Dupin in M\"obius geometry
and finally in Lie sphere geometry, where all nonumbilic Dupin immersions are
Lie sphere congruent to each other.Comment: To appear in the Shoshichi Kobayashi Memorial Volume of Progress in
Mathematics, Birkhause
Compact surfaces with no Bonnet mate
This note gives sufficient conditions (isothermic or totally nonisothermic)
for an immersion of a compact surface to have no Bonnet mate.Comment: 7 pages, LaTeX2
Outstanding Educational Performance Awards: Highlighting Top Achieving Arkansas Schools, 2009
Since our founding in 2003, the mission of the Office for Education Policy has been to look at pressing issues through the lens of academic research and disseminate our findings to educators, policymakers, and other stakeholders around Arkansas. Every once in a while, however, we think it is okay to stray from issue analysis and simply share some good news! So, in this Arkansas Education Report (AER) we merely aim to highlight excellent performance and give our congratulations. To that end, we are happy to highlight the top performing schools around the state in an annual AER entitled the Outstanding Educational Performance Awards
Outstanding Educational Performance Awards: Highlighting High Achieving Arkansas Schools, 2010
So, in this Arkansas Education Report (AER) we aim to highlight excellent performance and give our congratulations. To that end, we are happy to highlight many high performing schools around the state in our now-annual AER entitled the Outstanding Educational Performance Awards
Origin of last-glacial loess in the western Yukon-Tanana Upland, central Alaska, USA
Loess is widespread over Alaska, and its accumulation has traditionally been associated with glacial periods. Surprisingly, loess deposits securely dated to the last glacial period are rare in Alaska, and paleowind reconstructions for this time period are limited to inferences from dune orientations. We report a rare occurrence of loess deposits dating to the last glacial period, ~19 ka to ~12 ka, in the Yukon-Tanana Upland. Loess in this area is very coarse grained (abundant coarse silt), with decreases in particle size moving south of the Yukon River, implying that the drainage basin of this river was the main source. Geochemical data show, however, that the Tanana River valley to the south is also a likely distal source. The occurrence of last-glacial loess with sources to both the south and north is explained by both regional, synoptic-scale winds from the northeast and opposing katabatic winds that could have developed from expanded glaciers in both the Brooks Range to the north and the Alaska Range to the south. Based on a comparison with recent climate modeling for the last glacial period, seasonality of dust transport may also have played a role in bringing about contributions from both northern and southern sources
Enhanced tyrosine hydroxylase activity induces oxidative stress, causes accumulation of autotoxic catecholamine metabolites, and augments amphetamine effects in vivo.
In Parkinson\u27s disease, dopamine-containing nigrostriatal neurons undergo profound degeneration. Tyrosine hydroxylase (TH) is the rate-limiting enzyme in dopamine biosynthesis. TH increases in vitro formation of reactive oxygen species, and previous animal studies have reported links between cytosolic dopamine build-up and oxidative stress. To examine effects of increased TH activity in catecholaminergic neurons in vivo, we generated TH-over-expressing mice (TH-HI) using a BAC-transgenic approach that results in over-expression of TH with endogenous patterns of expression. The transgenic mice were characterized by western blot, qPCR, and immunohistochemistry. Tissue contents of dopamine, its metabolites, and markers of oxidative stress were evaluated. TH-HI mice had a 3-fold increase in total and phosphorylated TH levels and an increased rate of dopamine synthesis. Coincident with elevated dopamine turnover, TH-HI mice showed increased striatal production of
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