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On the Morgan-Shalen compactification of the SL(2,C) character varieties of surface groups
(1998)
A gauge theoretic description of the Morgan-Shalen compactification of the SL(2, C)
character variety of the fundamental group of a hyperbolic surface is given in terms of a natural compactification of the moduli space ...
Ubiquity of simplices in subsets of vector spaces over finite fields
(2007)
We prove that a sufficiently large subset of the $d$-dimensional vector space over a finite field with $q$ elements, $ {\Bbb F}_q^d$, contains a copy of every $k$-simplex. Fourier analytic methods, Kloosterman sums, and ...
Sums and products in finite fields: an integral geometric viewpoint
(2007)
We prove that if $A \subset {\Bbb F}_q$ is such that $$|A|>q^{{1/2}+\frac{1}{2d}},$$ then $${\Bbb F}_q^{*} \subset dA^2=A^2+...+A^2 d \text{times},$$ where $$A^2=\{a \cdot a': a,a' \in A\},$$ and where ${\Bbb F}_q^{*}$ ...
How often is a permutation an n'th power?
(1997)
We give a short argument that for any fixed n, the probability that a permutation on m letters is an n'th power is asymptotically C m^{phi(n)/n - 1}.
Time-dependent density-functional theory beyond the adiabatic approximation: Insights from a two-electron model system
(American Institute of Physics, 2006)
Most applications of time-dependent density-functional theory (TDDFT) use the adiabatic local-density approximation (ALDA) for the dynamical exchange-correlation potential Vxc(r,t). An exact (i.e., nonadiabatic) extension ...
Temperature and orientation dependence of kinetic roughening during homoepitaxy: A quantitative x-ray-scattering study of Ag
(American Physical Society, 1996)
Kinetic roughening during homoepitaxial growth was studied for Ag(111) and Ag(001). For Ag(111), from 150 to 500 K, the rms roughness exhibits a power law, σ∝tβ over nearly three decades in thickness. β≈1/2 at low temperatures, ...
Green building
(Rhetoric and Composition Program, University of Missouri--Columbia, 2010)
"Thinking Green" is the new buzzword of the twenty-first century. There are the green IBM commercials that demonstrate a substantial amount of money saved if a business, "goes green" the Mac commercial with the new energy ...
Complex pore spaces create record-breaking methane storage system for natural-gas vehicles
(American Institute of Physics, 2007)
It has been proposed that nearly space-filling networks of nanopores in biocarbon may provide a “sponge” for lowpressure,
high-capacity storage of methane CH4 for advanced transportation.1 Such pores, a few molecular ...
Transport and optical conductivity in dilute magnetic semiconductors
(Institute of Physics, 2009)
A theory of transport in spin and charge disordered media is developed, with a particular emphasis on dilute magnetic semiconductors. The approach is based on the equation of motion for the current-current response function ...
Enhanced hydrogen adsorption in boron substituted carbon nanospaces
(American Institute of Physics, 2009)
Activated carbons are one of promising groups of materials for reversible storage of hydrogen by physisorption. However, the heat of hydrogen adsorption in such materials is relatively low, in the range of about 4-8 kJ/mol, ...
Nonuniqueness in spin-density-functional theory on lattices
(American Physical Society, 2005)
In electronic many-particle systems, the mapping between densities and spin magnetizations, {n(r),m(r)}, and potentials and magnetic fields, {v(r),B(r)}, is known to be nonunique, which has fundamental and practical ...
Real-Time Electron Dynamics with Exact-Exchange Time-Dependent Density-Functional Theory
(American Physical Society, 2008)
The exact exchange potential in time- dependent density-functional theory is defined as an orbital functional through the time-dependent optimized effective potential (TDOEP) method. We numerically solve the TDOEP integral ...
Intersubband spin-orbit coupling and spin splitting in symmetric quantum wells
(arXiv, 2007)
In semiconductors with inversion asymmetry, spin-orbit coupling gives rise to the well-known Dresselhaus and Rashba effects. If one considers quantum wells with two or more conduction subbands, an additional, intersubband-induced ...
Was the need to produce pesticides higher than need to protect civilians?
(Rhetoric and Composition Program, University of Missouri--Columbia, 2010)
Your blood turns cold. Your eyes become blind. Panic hits and all of a sudden air won't enter your lungs quite as easily. In the dead of the night of December 3rd, a noise resembling the pain of thousands of people was ...
Spin-Hall effect and spin-Coulomb drag in doped semiconductors
(American Institute of Physics, 2009)
In this review, we describe in detail two important spin-transport phenomena: the extrinsic spin-Hall effect (coming from spin-orbit interactions between electrons and impurities) and the spin-Coulomb drag. The interplay ...
Linear response of doped graphene sheets to vector potentials
(American Physical Society, 2009)
A two-dimensional gas of massless Dirac fermions (MDFs) is a very useful model to describe low-energy electrons in monolayer graphene. Because the MDF current operator is directly proportional to the (sublattice) pseudospin ...
Liquid crystalline states for two-dimensional electrons in strong magnetic fields
(American Physical Society, 2004)
Based on the Kosterlitz-Thouless-Halperin-Nelson-Young theory of two-dimensional melting and the analogy between Laughlin states and the two-dimensional one-component plasma, we investigate the possibility of liquid ...
Magnetic and Orbital Order in LaMnO3 under Uniaxial Strain: A Model Study
(arXiv, 2009)
The effect of uniaxial strain on electronic structure and magnetism in LaMnO3 is studied from a
model Hamiltonian that illustrates the competition between the Jahn-Teller, super exchange, and
double exchange interactions. ...
Polar catastrophe, electron leakage, and magnetic ordering at the LaMnO3/SrMnO3 interface
(arXiv, 2009)
Electronic reconstruction at the polar interface LaMnO3/SrMnO3 (LMO/SMO) (100) resulting
from the polar catastrophe is studied from a model Hamiltonian that includes the double and super exchange interactions, the Madelung ...
Collective excitations in quantum Hall liquid crystals: Single-mode approximation calculations
(American Physical Society, 2006)
A variety of recent experiments probing the low-temperature transport properties of quantum Hall systems have suggested an interpretation in terms of liquid crystalline mesophases dubbed quantum Hall liquid crystals. The ...