733 research outputs found
Geometric representation of interval exchange maps over algebraic number fields
We consider the restriction of interval exchange transformations to algebraic
number fields, which leads to maps on lattices. We characterize
renormalizability arithmetically, and study its relationships with a
geometrical quantity that we call the drift vector. We exhibit some examples of
renormalizable interval exchange maps with zero and non-zero drift vector, and
carry out some investigations of their properties. In particular, we look for
evidence of the finite decomposition property: each lattice is the union of
finitely many orbits.Comment: 34 pages, 8 postscript figure
Cross sections for geodesic flows and \alpha-continued fractions
We adjust Arnoux's coding, in terms of regular continued fractions, of the
geodesic flow on the modular surface to give a cross section on which the
return map is a double cover of the natural extension for the \alpha-continued
fractions, for each in (0,1]. The argument is sufficiently robust to
apply to the Rosen continued fractions and their recently introduced
\alpha-variants.Comment: 20 pages, 2 figure
Triangulations and Severi varieties
We consider the problem of constructing triangulations of projective planes
over Hurwitz algebras with minimal numbers of vertices. We observe that the
numbers of faces of each dimension must be equal to the dimensions of certain
representations of the automorphism groups of the corresponding Severi
varieties. We construct a complex involving these representations, which should
be considered as a geometric version of the (putative) triangulations
Observation of confined current ribbon in JET plasmas
we report the identification of a localised current structure inside the JET
plasma. It is a field aligned closed helical ribbon, carrying current in the
same direction as the background current profile (co-current), rotating
toroidally with the ion velocity (co-rotating). It appears to be located at a
flat spot in the plasma pressure profile, at the top of the pedestal. The
structure appears spontaneously in low density, high rotation plasmas, and can
last up to 1.4 s, a time comparable to a local resistive time. It considerably
delays the appearance of the first ELM.Comment: 10 pages, 6 figure
Theory-based scaling of the SOL width in circular limited tokamak plasmas
A theory-based scaling for the characteristic length of a circular, limited tokamak scrape-off layer (SOL) is obtained by considering the balance between parallel losses and non-linearly saturated resistive ballooning mode turbulence driving anomalous perpendicular transport. The SOL size increases with plasma size, resistivity, and safety factor q. The scaling is verified against flux-driven non-linear turbulence simulations, which reveal good agreement within a wide range of dimensionless parameters, including parameters closely matching the TCV tokamak. An initial comparison of the theory against experimental data from several tokamaks also yields good agreement
Update of variants identified in the pancreatic β-cell K ATP channel genes KCNJ11 and ABCC8 in individuals with congenital hyperinsulinism and diabetes
The most common genetic cause of neonatal diabetes and hyperinsulinism is pathogenic variants in ABCC8 and KCNJ11. These genes encode the subunits of the β-cell ATP-sensitive potassium channel, a key component of the glucose-stimulated insulin secretion pathway. Mutations in the two genes cause dysregulated insulin secretion; inactivating mutations cause an oversecretion of insulin, leading to congenital hyperinsulinism, whereas activating mutations cause the opposing phenotype, diabetes. This review focuses on variants identified in ABCC8 and KCNJ11, the phenotypic spectrum and the treatment implications for individuals with pathogenic variants.This article is freely available via Open Access. Click on the publisher URL to access it via the publisher's site.P30 DK020595/NH/NIH HHS/United States
K23 DK094866/NH/NIH HHS/United States
R03 DK103096/NH/NIH HHS/United States
1-11-CT-41/American Diabetes Association/International
R01 DK104942/DK/NIDDK NIH HHS/United States
WT_/Wellcome Trust/United Kingdom
WT098395/Z/12/Z/WT_/Wellcome Trust/United Kingdom
UL1 TR000430/NH/NIH HHS/United States
P30 DK020595/DK/NIDDK NIH HHS/United States
UL1 TR000430/TR/NCATS NIH HHS/United States
1-17-JDF-008/American Diabetes Association/International
105636/Z/14/Z/WT_/Wellcome Trust/United Kingdom
110675/European Association for the Study of Diabetes-Novo Nordisk/International
16/0005407/DUK_/Diabetes UK/United Kingdom
R01 DK104942/NH/NIH HHS/United States
R03 DK103096/DK/NIDDK NIH HHS/United States
K23 DK094866/DK/NIDDK NIH HHS/United Statespublished version, accepted version (12 month embargo), submitted versio
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