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Microscopic Fourier transform infrared spectroscopy (FTIR) which is based on the characteristic molecular vibrational spectra of cells was previously applied for the identification of various biological samples. In the present study, FTIR spectroscopy was used for the characterization of different stages during the development of herpes viruses infection. Vero cells in culture were infected with high and low doses of different herpes viruses [herpes simplex virus types 1 and 2 (HSV-1, -2) or varicella-zoster virus (VZV)], and cellular changes were observed by optical and electron microscopy and analyzed by FTIR microscopy at different periods of time post-infection. Specific different spectral changes were observed at various stages of the viral infection development. The spectral intensity in the 1220–1260 cm−1region (mainly attributed to phosphate levels) was considerably increased in all infected cells compared to normal uninfected cells during the early stages of the viral infection development. However, at the late stages of the viral infection development (when all the cells in the infected culture lost their spindle shape and became circular) the spectral intensities in this region significantly decreased in the infected compared to the control cells. In addition, the peak at 1023 cm−1, attributed to carbohydrates, almost fully disappeared at early stages of the viral infection development, whereas at late stages of the infection it raised to an equivalent or higher level than that of the uninfected control cells. These results support the potential of developing FTIR microspectroscopy as a simple, reagent free method for the early detection and accurate differentiation of different stages during the development of herpes virus infection. [ABSTRACT FROM AUTHOR]

In last decades infrared spectroscopy has demonstrated potential as a novel technology for early cancer diagnosis. Among the various IR spectroscopic techniques special interest has arisen from methods based on evanescent wave absorbance due to the possibility for in situand in vivoimplementation. The goal of the present study is to examine the potential of Attenuated Total Reflectance (ATR) spectroscopy for early detection of premalignant changes. As a model we used both cell lines and primary cells, which were transformed to be malignant by a retrovirus. Spectral measurements were performed at various post infection stages in parallel with morphological observations. Our results showed gradual and consistent spectral alterations in both cell cultures due to carcinogenesis, which were outlined using Principal Component Analysis (PCA). The main spectral differences appeared in three spectral ranges: at 3000–2800 cm−1(attributed to stretching vibrational modes of lipids and proteins), at 1470–1300 cm−1(attributed to bending overlapping modes of lipids and proteins) and also at the highly overlapping spectral range at 1000–1200 cm−1(attributed to bending and starching vibrational modes corresponding to all types of biological macromolecules). In order to obtain robust unsupervised classifications of the malignant progression we applied approaches of Linear Discriminant Analysis (LDA). The classifications based on Mahalanobis distances allowed us to discern that the accuracy of successful identification of premalignant stages varied between 86.5–97.2%. Our results show that ATR spectroscopy in tandem with proper statistical tools may provide a promising technique for early detectable signals of malignant progression. [ABSTRACT FROM AUTHOR]

It is well established numerically that spectral statistics of pseudo-integrable models differs considerably from the reference statistics of integrable and chaotic systems. In Bogomolny and Schmit (2004 Phys. Rev. Lett. 93 254102) statistical properties of a certain quantized pseudo-integrable map had been calculated analytically but only for a special sequence of matrix dimensions. The purpose of this paper is to obtain the spectral statistics of the same quantum map for all matrix dimensions. [ABSTRACT FROM AUTHOR]

Recently it was conjectured that nodal domains of random wavefunctions are adequately described by critical percolation theory. In this paper we strengthen this conjecture in two respects. First, we show that, though wavefunction correlations decay slowly, a careful use of Harris' criterion confirms that these correlations are unessential and nodal domains of random wavefunctions belong to the same universality class as non-correlated critical percolation. Second, we argue that level domains of random wavefunctions are described by the non-critical percolation model. [ABSTRACT FROM AUTHOR]

The nodal lines of random wavefunctions are investigated. We demonstrate numerically that they are well approximated by the so-called SLE6curves which describe the continuum limit of the percolation cluster boundaries. This result gives additional support to the recent conjecture that the nodal domains of random (and chaotic) wavefunctions in the semi-classical limit are adequately described by the critical percolation theory. It is also shown that using the dipolar variant of SLE reduces significantly finite size effects. [ABSTRACT FROM AUTHOR]

The problem of two Aharonov–Bohm (AB) vortices for the Helmholtz equation is examined in detail. It is demonstrated that the method proposed by Myers (1963 J. Math. Phys.6 1839) for slit diffraction can be generalised to obtain an explicit solution for AB vortices. Due to the singular nature of AB interaction the Green function and scattering amplitude for two AB vortices obey a series of partial differential equations. Coefficients entering these equations, fulfil ordinary non-linear differential equations whose solutions can be obtained by solving the Painlevé III equation. The asymptotics of necessary functions for very large and very small vortex separations are calculated explicitly. Taken together, this means that the problem of two AB vortices is exactly solvable. [ABSTRACT FROM AUTHOR]

The emission from open cavities with non-integrable features remains a challenging problem of practical as well as fundamental relevance. Square-shaped dielectric microcavities provide a favorable case study with generic implications for other polygonal resonators. We report on a joint experimental and theoretical study of square-shaped organic microlasers exhibiting a far-field emission that is strongly concentrated in the directions parallel to the side walls of the cavity. A semiclassical model for the far-field distributions is developed that is in agreement with even fine features of the experimental findings. Comparison of the model calculations with the experimental data allows the precise identification of the lasing modes and their emission mechanisms, providing strong support for a physically intuitive ray-dynamical interpretation. Special attention is paid to the role of diffraction and the finite side length. [ABSTRACT FROM AUTHOR]