Snapshot Mueller matrix spectropolarimeter

We present a new snapshot technique for performing spectrally resolved Mueller matrix polarimetry. The basic approach is an extension of the channeled spectropolarimetry technique, employing frequency-domain interferometry to encode polarization information into modulation of the spectrum.     

Spectroscopic and theoretical studies of optically active porphyrin dimers: a system uninterpretable by exciton coupling theory.

The electronic excited states of a meso-meso beta-beta doubly linked bis-porphyrin are comprehensively investigated by measuring its circular dichroism (CD) and magnetic circular dichroism (MCD) spectra. The observed spectroscopic properties are rationalized by DFT calculations. The frontier molecular orbitals (MOs) are constructed by the linear combinations of the constituent monomers' four MOs. Comparison of a theoretical CD spectrum based on time-dependent DFT (TDDFT) with the experimental spectra resulted in the assignment of the helical conformation of the dimer. This assignment is contrary to the previous assignment based on the point-dipole approximation (exciton coupling theory).     

Three dimensional gain analysis of free electron laser with focusing permanent magnet wiggler

A three dimensional simulation software system developed to estimate a free electron laser (FEL) gain has been applied to FEL using a standard plane polarized wiggler and an alternately shifted magnet wiggler. It is seen for the latter wiggler that a large filling factor could be selected and each maximum gain corresponding to each orbit of electron beam concentrates at a certain frequency region of FEL radiation. It is, therefore, implied that a proper shift between the adjacent magnets in the wiggler produces the improvement of the FEL gain.     

Dynamic photoelastic analysis by optical heterodyne polarimetry

This paper describes the mapping of the spatiotemporal principal stress distribution evolved with time in an epoxy photoelastic sample. In the optical heterodyne polarimeter exploited, the signal beam of light transmitted by the sample under continuously loaded condition is photomixed with the local oscillator beam of light made up of orthogonal linearly polarized two-frequency components. Every pixel of a MOS video camera used generates a beat photocurrent that possesses the two orthogonal field components of the elliptically polarized signal beam. The spatiotemporal principal stress distributions can be uniquely determined simultaneously and independently from these two orthogonal field components, and are successfully mapped in a time-sequential form. The spatial and temporal resolutions in the maps are 0.18 mm and 2.9 ms, respectively.     

On global stability of an HIV pathogenesis model with cure rate

In this paper, applying both Lyapunov function techniques and monotone iterative techniques, we establish new sufficient conditions under which the infected equilibrium of an HIV pathogenesis model with cure rate is globally asymptotically stable. By giving an explicit expression for eventual lower bound of the concentration of susceptible CD4⁺ T cells, we establish an affirmative partial answer to the numerical simulations investigated in the recent paper [Liu, Wang, Hu and Ma, Global stability of an HIV pathogenesis model with cure rate, Nonlinear Analysis RWA (2011) 12 : 2947–2961]. Our monotone iterative techniques are applicable for the small and large growth rate in logistic functions for the proliferation rate of healthy and infected CD4⁺ T cells. Copyright © 2014 John Wiley & Sons, Ltd.     

Fundamental groups of the complements of certain plane non-tame torus sextics

The moduli space of torus sextics with the configuration of singularities {A₂+A₅+2E₆} has two connected components. We compute the fundamental groups π₁(CP²−C) for sextics C in both components and study their differences.     

Unipotent Algebraic Affine Supergroups and Nilpotent Lie Superalgebras

We characterize hereditary (as coalgebras) Hopf algebras by the property of ‘equivariant smoothness’, and apply the result to generalize to the super-context, the category equivalence, due to Hochschild, between the unipotent algebraic affine groups and the finite-dimensional nilpotent Lie algebras, in characteristic zero. The global dimension of commutative Hopf algebras, regarded as coalgebras, is also discussed. Presented by S. Montgomery Mathematics Subject Classification (2000) 16W30.     

Visualization of space charge field effect on excitons in a GaAs quantum dot by near-field optical wavefunction mapping

Near-field photoluminescence (PL) imaging spectroscopy was used to investigate multi-exciton and charged-exciton states confined in a single GaAs interface fluctuation quantum dot. We determined the origin of peaks in the PL spectra by employing a wavefunction mapping technique. We observed distortion of the exciton wavefunction due to the electric field produced by an excess electron at a nearby confined state. Near-field wavefunction mapping was demonstrated to be a powerful tool for visualizing the local environment, which affects the emission properties of quantum dots.