Modeling of space-polarization parameters and heterogeneity effect on the spectral characteristics of wideband filters

На даний час не вирішеною залишається проблема модельного представлення неоднорідностей в частково неоднорідних плівках при неперервній зміні показника заломлення на межах розділу. В роботі наведено узагальнені зміни параметрів спектрів пропускання багатошарових інтерференційних структур (БІС) широкосмугових оптичних фільтрів залежно від поляризації та кута падіння паралельних потоків випромінювання відносно нормалі до їх поверхні. Розроблено модель та досліджено вплив перехідної області з неоднорідним розподілом показника заломлення на спектральні характеристики широкосмугових фільтрів залежно від кута.At present time there are still unsolved the problem of model representation of heterogeneity in slightly inhomogeneous films with continuous change of the refractive index at the interfaces. There are studies in frame of inhomogeneous layered model which does not reflect the angular and polarization dependences of the spectral characteristics of broadband filters. In this work generalized change of parameters of multilayer interference structures were obtained from the analysis of light transmission spectra. The angular and polarization dependences of transmission of multilayer interference structures (broadband interference filters, BIS) with inhomogeneities on interfaces have been investigated. There were shown changes in the parameters of transmission spectra are depending on polarization and angle of incidence parallel beams of radiation relative to the normal to the surface. The effect of the working wavelength change on the spectral characteristics of broadband optical filters was investigated. For calculation available working wavelength at 480, 630, 750, 1000 and 3000 nm are used. In the submitted paper the inhomogeneous model of the refractive index profile was developed, which includes transition region in high refractive index layer on interfaces. The spectral characteristics of broadband filters and its dependence on the incident angle and polarization of light, influence of transition layer on the interfaces between layers have been investigated. The basic parameters which are influenced on changing of transmission spectra of multilayer interference structures were found. The influence of operating wavelength changes on the spectral characteristics of broadband optical filters with the transition regions was investigated. The results are particularly relevant for determining the effectiveness of the use of convergence or divergence of the radiation beams in optical systems with such filters. The features of the spectral characteristics of the slightly inhomogeneous films with different types of refractive index distribution on interfaces and mathematical modeling can broaden the applicability of non-crystalline films during manufacturing of BIS

Raman spectra and electron microscopic investigations of the sections of modified As₂S₃ glasses

Chalcogenide vitreous semiconductors (ChVS) are used as memory elements, elements of fiber, integral and power optics [1–6]. The change of the synthesis conditions results in the change of structure and, as a consequence, physical parameters of ChVS [1]. It means that it is possible to find solution of the fabrication of glasses with high optical strength by using modification of ChVS structure [2]. The objective of the present work is to investigate the influence of the temperature-temporal conditions of the fabrication on the structure of As₂S₃ glasses by the method of the Raman scattering spectroscopy and electron microscopy and also to choose the conditions of fabrication of As₂S₃ glasses with the continuously bonded matrix of the structure suitable for power optics using this basis

Nano-sized phase inclusions in As₂S₃ glass, films and fibers based on this glass

In this report, the comparative analysis using Raman spectroscopy of the short-range order in amorphous As₂S₃ films deposited with different evaporation rates, volume glass and fiber based on this glass is presented. With increasing the film deposition rate, their structure becomes more non-uniform as compared to that of glass. Raman spectra excited by laser radiation with energy bigger than the width of the optical gap indicate photomodification of the structure of As₂S₃ glass and fiber based on it

The Utility of Data Transformation for Alignment, De Novo Assembly and Classification of Short Read Virus Sequences.

Advances in DNA sequencing technology are facilitating genomic analyses of unprecedented scope and scale, widening the gap between our abilities to generate and fully exploit biological sequence data. Comparable analytical challenges are encountered in other data-intensive fields involving sequential data, such as signal processing, in which dimensionality reduction (i.e., compression) methods are routinely used to lessen the computational burden of analyses. In this work, we explored the application of dimensionality reduction methods to numerically represent high-throughput sequence data for three important biological applications of virus sequence data: reference-based mapping, short sequence classification and de novo assembly. Leveraging highly compressed sequence transformations to accelerate sequence comparison, our approach yielded comparable accuracy to existing approaches, further demonstrating its suitability for sequences originating from diverse virus populations. We assessed the application of our methodology using both synthetic and real viral pathogen sequences. Our results show that the use of highly compressed sequence approximations can provide accurate results, with analytical performance retained and even enhanced through appropriate dimensionality reduction of sequence data

The Complete Genome Sequence of ‘Candidatus Liberibacter solanacearum’, the Bacterium Associated with Potato Zebra Chip Disease

Zebra Chip (ZC) is an emerging plant disease that causes aboveground decline of potato shoots and generally results in unusable tubers. This disease has led to multi-million dollar losses for growers in the central and western United States over the past decade and impacts the livelihood of potato farmers in Mexico and New Zealand. ZC is associated with ‘Candidatus Liberibacter solanacearum’, a fastidious alpha-proteobacterium that is transmitted by a phloem-feeding psyllid vector, Bactericera cockerelli Sulc. Research on this disease has been hampered by a lack of robust culture methods and paucity of genome sequence information for ‘Ca. L. solanacearum’. Here we present the sequence of the 1.26 Mbp metagenome of ‘Ca. L. solanacearum’, based on DNA isolated from potato psyllids. The coding inventory of the ‘Ca. L. solanacearum’ genome was analyzed and compared to related Rhizobiaceae to better understand ‘Ca. L. solanacearum’ physiology and identify potential targets to develop improved treatment strategies. This analysis revealed a number of unique transporters and pathways, all potentially contributing to ZC pathogenesis. Some of these factors may have been acquired through horizontal gene transfer. Taxonomically, ‘Ca. L. solanacearum’ is related to ‘Ca. L. asiaticus’, a suspected causative agent of citrus huanglongbing, yet many genome rearrangements and several gene gains/losses are evident when comparing these two Liberibacter. species. Relative to ‘Ca. L. asiaticus’, ‘Ca. L. solanacearum’ probably has reduced capacity for nucleic acid modification, increased amino acid and vitamin biosynthesis functionalities, and gained a high-affinity iron transport system characteristic of several pathogenic microbes

Localized States Model of GeS2 Glasses Based on Electronic States of GenSm Clusters Calculated by Using TD-DFT Method

The first-principles calculation based on time dependent - density functional theory (TDDFT) reveals the origin of the molecular electronic structure and its connection to the localized states of the g-GeS2(T-i). The band gaps computed for GenSm clusters representing the local structures and their correlation to the experimental band gaps of g-GexS100-x together with possible model of band-tail states of g-GeS2 have been discussed. According to the observed results we propose to consider the band-gap states of g-GexS100-x as superposition of electronic states of GenSm clusters. The type and concentration of these clusters are compositionally-dependent and influenced by technological conditions used for glass preparation

Boson peak in low-frequency Raman spectra of AsxS100-x glasses: nanocluster contribution

The origin of the Boson peak was investigated using Raman spectroscopy and ab initio calculations. Low frequency Raman active vibrational modes of different branchy-, ring- and cage-like AsmSn nanoclusters were calculated and compared to experimentally determined Raman spectra of AsxS100-x glasses with different compositon. A good correlation was found between the spectral features and the calculated Raman modes. The possible structural nature of the Boson peak in arsenic chalcogenides is proposed and discussed