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Equivariant semidefinite lifts of regular polygons
(Institute for Operations Research and the Management SciencesMathematics of Operations Research, 2017-05-01)
Given a polytope P in $\mathbb{R}^n$, we say that P has a positive
semidefinite lift (psd lift) of size d if one can express P as the linear
projection of an affine slice of the positive semidefinite cone
$\mathbf{S}^d_+$. ...
Lieb's concavity theorem, matrix geometric means, and semidefinite optimization
(Linear Algebra and Its Applications, 2017-01-15)
A famous result of Lieb establishes that the map (A,B)↦tr[K^* A^{1−t}KB^{t}] is jointly concave in the pair (A,B) of positive definite matrices, where K is a fixed matrix and t∈[0,1]. In this paper we show that Lieb's ...
Five vortex equations
(IOP PublishingJournal of Physics A: Mathematical and Theoretical, 2017-02-24)
The Taubes equation for Abelian Higgs vortices is generalised to five distinct U(1) vortex equations. These include the Popov and Jackiw–Pi vortex equations, and two further equations. The Baptista metric, a conformal ...
An experimental study of the spread of buoyant water into a rotating environment
(University of CambridgeDepartment of Applied Maths and Theoretical PhysicsQueens', 2017-05-01)
This thesis examines previously unresolved issues regarding the fluid dynamics of the spread of buoyant water into a rotating environment. We focus in particular on the role that finite potential vorticity and background ...
Probing the Gravitational Dependence of the Fine-Structure Constant from Observations of White Dwarf Stars
(Multidisciplinary Digital Publishing InstituteUniverse, 2017-06-01)
Hot white dwarf stars are the ideal probe for a relationship between the fine-structure constant and strong gravitational fields, providing us with an opportunity for a direct observational test. We study a sample of hot ...
Contractile and chiral activities codetermine the helicity of swimming droplet trajectories
(National Academy of SciencesProceedings of the National Academy of Sciences of the United States of America, 2017-05-02)
Active fluids are a class of nonequilibrium systems where energy is injected into the system continuously by the constituent particles themselves. Many examples, such as bacterial suspensions and actomyosin networks, are ...
Function of bacteriophage G7C esterase tailspike in host cell adsorption.
(Molecular microbiology, 2017-08)
Swimming with a cage: low-Reynolds-number locomotion inside a droplet
(Royal Society of ChemistrySoft Matter, 2017-05-07)
Inspired by recent experiments using synthetic microswimmers to manipulate droplets, we investigate the low-Reynolds-number locomotion of a model swimmer (a spherical squirmer) encapsulated inside a droplet of a comparable ...
Hadroquarkonium from lattice QCD
(American Physical SocietyPhyscial Review D, 2017-04-03)
he hadroquarkonium picture [S. Dubynskiy and M. B. Voloshin, Phys. Lett. B 666, 344 (2008)] provides one possible interpretation for the pentaquark candidates with hidden charm, recently reported by the LHCb Collaboration, ...
Meson Spectroscopy from Lattice QCD
(SpringerFew-Body Systems, 2017-05-01)
Some recent progress in using lattice QCD to perform first-principles calculations of the spectra of mesons is discussed. In particular, I highlight some new results on resonances, near-threshold states and related scattering ...