39,848 research outputs found
The classification of 2-compact groups
We prove that any connected 2-compact group is classified by its 2-adic root
datum, and in particular the exotic 2-compact group DI(4), constructed by
Dwyer-Wilkerson, is the only simple 2-compact group not arising as the
2-completion of a compact connected Lie group. Combined with our earlier work
with Moeller and Viruel for p odd, this establishes the full classification of
p-compact groups, stating that, up to isomorphism, there is a one-to-one
correspondence between connected p-compact groups and root data over the p-adic
integers. As a consequence we prove the maximal torus conjecture, giving a
one-to-one correspondence between compact Lie groups and finite loop spaces
admitting a maximal torus. Our proof is a general induction on the dimension of
the group, which works for all primes. It refines the
Andersen-Grodal-Moeller-Viruel methods to incorporate the theory of root data
over the p-adic integers, as developed by Dwyer-Wilkerson and the authors, and
we show that certain occurring obstructions vanish, by relating them to
obstruction groups calculated by Jackowski-McClure-Oliver in the early 1990s.Comment: 47 page
Driving steady-state visual evoked potentials at arbitrary frequencies using temporal interpolation of stimulus presentation
Date of Acceptance: 29/10/2015 We thank Renate Zahn for help with data collection. This work was supported by Deutsche Forschungsgemeinschaft (AN 841/1-1, MU 972/20-1). We would like to thank A. Trujillo-Ortiz, R. Hernandez-Walls, A. Castro-Perez and K. BarbaRojo (Universidad Autonoma de Baja California) for making Matlab code for non-sphericity corrections freely available.Peer reviewedPublisher PD
The C*-algebra of an affine map on the 3-torus
We study the C*-algebra of an affine map on a compact abelian group and give
necessary and sufficient conditions for strong transitivity when the group is a
torus. The structure of the C*-algebra is completely determined for all
strongly transitive affine maps on a torus of dimension one, two or three
Weak and saturable protein-surfactant interactions in the denaturation of apo-α-lactalbumin by acidic and lactonic sophorolipid
Biosurfactants are of growing interest as sustainable alternatives to fossil-fuel-derived chemical surfactants, particularly for the detergent industry. To realize this potential, it is necessary to understand how they affect proteins which they may encounter in their applications. However, knowledge of such interactions is limited. Here, we present a study of the interactions between the model protein apo-alpha-lactalbumin (apo-aLA) and the biosurfactant sophorolipid (SL) produced by the yeast Starmerella bombicola. SL occurs both as an acidic and a lactonic form; the lactonic form (lactSL) is sparingly soluble and has a lower critical micelle concentration (cmc) than the acidic form [non-acetylated acidic sophorolipid (acidSL)]. We show that acidSL affects apo-aLA in a similar way to the related glycolipid biosurfactant rhamnolipid (RL), with the important difference that RL is also active below the cmc in contrast to acidSL. Using isothermal titration calorimetry data, we show that acidSL has weak and saturable interactions with apo-aLA at low concentrations; due to the relatively low cmc of acidSL (which means that the monomer concentration is limited to ca. 0-1 mM SL), it is only possible to observe interactions with monomeric acidSL at high apo-aLA concentrations. However, the denaturation kinetics of apo-aLA in the presence of acidSL are consistent with a collaboration between monomeric and micellar surfactant species, similar to RL and non-ionic or zwitterionic surfactants. Inclusion of diacetylated lactonic sophorolipid (lactSL) as mixed micelles with acidSL lowers the cmc and this effectively reduces the rate of unfolding, emphasizing that SL like other biosurfactants is a gentle anionic surfactant. Our data highlight the potential of these biosurfactants for future use in the detergent and pharmaceutical industry
Band structure and atomic sum rules for x-ray dichroism
Corrections to the atomic orbital sum rule for circular magnetic x-ray
dichroism in solids are derived using orthonormal LMTOs as a single-particle
basis for electron band states.Comment: 7 pages, no figure
Construction of transferable spherically-averaged electron potentials
A new scheme for constructing approximate effective electron potentials
within density-functional theory is proposed. The scheme consists of
calculating the effective potential for a series of reference systems, and then
using these potentials to construct the potential of a general system. To make
contact to the reference system the neutral-sphere radius of each atom is used.
The scheme can simplify calculations with partial wave methods in the
atomic-sphere or muffin-tin approximation, since potential parameters can be
precalculated and then for a general system obtained through simple
interpolation formulas. We have applied the scheme to construct electron
potentials of phonons, surfaces, and different crystal structures of silicon
and aluminum atoms, and found excellent agreement with the self-consistent
effective potential. By using an approximate total electron density obtained
from a superposition of atom-based densities, the energy zero of the
corresponding effective potential can be found and the energy shifts in the
mean potential between inequivalent atoms can therefore be directly estimated.
This approach is shown to work well for surfaces and phonons of silicon.Comment: 8 pages (3 uuencoded Postscript figures appended), LaTeX,
CAMP-090594-
Free vibrations of laminated composite elliptic plates
The free vibrations are studied of laminated anisotropic elliptic plates with clamped edges. The analytical formulation is based on a Mindlin-Reissner type plate theory with the effects of transverse shear deformation, rotary inertia, and bending-extensional coupling included. The frequencies and mode shapes are obtained by using the Rayleigh-Ritz technique in conjunction with Hamilton's principle. A computerized symbolic integration approach is used to develop analytic expressions for the stiffness and mass coefficients and is shown to be particularly useful in evaluating the derivatives of the eigenvalues with respect to certain geometric and material parameters. Numerical results are presented for the case of angle-ply composite plates with skew-symmetric lamination
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