Self-induced liquid crystal q-plate by photoelectric interface activation

International audienceHere, we report on the experimental demonstration that highly efficient self-induced spin-orbit optical vortex generation can be achieved by using standard liquid crystal materials and surface treatment agents. This is done by revisiting the recent attempt by Zolot’ko and coworkers to produce self-induced liquid crystal vortex plates using the dc electric field [I. A. Budagovsky, S. A. Shvetsov, and A. S. Zolot’ko, Mol. Cryst. Liq. Cryst. 637, 47 (2016)] that remains, so far, limited to moderate efficiencies. The phenomenon is the result of the self-back-action of light arising from the spontaneous creation of a liquid crystal topological defect. These results demonstrate photo-electric interface activation as a candidate towards the development of a self-adapted spinorbit photonic toolbox, thus enabling agile management of the orbital angular momentum of light

Large effect of a small bias field in liquid-crystal magnetic transitions

Most liquid crystals show low sensitivity to magnetic field. However, in this paper we show that a small bias magnetic field not only breaks the symmetry of the ground state, but also plays a crucial role in facilitating the reorientation induced by a large test magnetic field. In particular, a small bias field may alter significantly the strength of the test field needed to observe a given reorientation of the liquid crystal. Moreover, the bias field interacts with other symmetry breaking features of the cell, e.g., pretilt, to change also the qualitative features of the equilibrium state

Voltage transfer function as an optical method to characterize electrical properties of liquid crystal devices

The voltage transfer function is a rapid and visually effective method to determine the electrical response of liquid crystal (LC) systems using optical measurements. This method relies on cross-polarized intensity measurements as a function of the frequency and amplitude of the voltage applied to the device. Coupled with a mathematical model of the device it can be used to determine the device time constants and electrical properties. We validate the method using photorefractive LC cells and determine the main time constants and the voltage dropped across the layers using a simple nonlinear filter model

Light-activated modulation and coupling in integrated polymer-liquid crystal systems

We explore the transfer of an incident light pattern onto the liquid crystal (LC) bulk in a photorefractive cell through an integrated photoconducting layer that modulates the electric field applied to the device. The electrical properties and the strength of modulation are investigated as a function of the incident light intensity as well as the frequency and amplitude of the applied voltage, for two LCs with very different electrical conductivity. A simplified electrical model of the cell is proposed, demonstrating that the LC conductivity is a key factor determining the beam-coupling strength

Regulation of Nucleotide Excision Repair by UV-DDB: Prioritization of Damage Recognition to Internucleosomal DNA

This study reveals the molecular mechanism by which the nucleotide excision repair protein DDB2 prioritises excision of UV-induced DNA lesions in the nucleosome landscape

Investment Activity and Technological Opportunities for Human Capital Development. The Case of the “Pszukaj” Application for Ukrainian Refugees in Poland

Theoretical background: Human capital is one of the key factors in the development of entrepreneurship, production and services. The goal of each enterprise is to make a profit, the realization of which requires investment. When developing investment projects, it is crucial to choose the most promising ones, at the same time, it is necessary to take into account the existence of “bottlenecks”, and investment activity should be directed to liquidate them. So, the optimal values of the enterprises’ investments in the situation of sufficient and insufficient levels of human capital are found and the factors influencing them are analyzed. The study of the issue of human capital today cannot bypass the question of refugees. As a result of the war in Ukraine, a large wave of migration processes is taking place in Poland, and, therefore, there is a problem and need for adaptation of people fleeing from the war. The social problem that arose due to the large number of refugees in Poland requires a comprehensive solution that would aim not only to help the refugees, but also the Polish economy. The best possible solution to the problem of refugees, both for themselves and for the host countries, is to involve them in an egalitarian society and equal economic life. The study highlights the possibility of using technical capabilities for the development of human capital on the example of a mobile application “Pszukaj” developed by the authors. Purpose of the article: The aim of this paper is to build and analyze optimization models of investments in the field of production of goods and provision of services and in the development of human capitalin the situation of sufficient and insufficient levels of human capital development. The practical research question of this study is to consider the case of the “Pszukaj” mobile application as a communication tool for refugees wishing to function independently in Polish society. Research methods: The role of human capital in the enterprises’ activities will be evaluated based on constructed investment optimization models. The importance of technological opportunities for human capital development will be evaluated based on the case of the “Pszukaj” mobile application. Main findings: This study contributes to the existing research by offering the analysis of constructed investment optimization models in situation of sufficient and insufficient levels of human capital. The dependence of the optimal values of investments in the development of the sphere of production of goods and provision of services and in human capital on both efficiency indicators of investments in the corresponding directions is shown and analyzed. From the practical perspective, the value of technological opportunities for human capital on the example of "Pszukaj" is shown

Topological learning for the classification of disorder: an application to the design of metasurfaces

Structural disorder can improve the optical properties of metasurfaces, whether it is emerging from some large-scale fabrication methods, or explicitly designed and built lithographically. Correlated disorder, induced by a minimum inter-nanostructure distance or by hyperuniformity properties, is particularly beneficial in some applications such as light extraction. We introduce numerical descriptors inspired from topology to provide quantitative measures of disorder whose universal properties make them suitable for both uncorrelated and correlated disorder, where statistical descriptors are less accurate. We prove theoretically and experimentally the accuracy of these topological descriptors of disorder by using them to design plasmonic metasurfaces of controlled disorder, that we correlate to the strength of their surface lattice resonances. These tools can be used for the fast and accurate design of disordered metasurfaces, or to help tuning large-scale fabrication methods.Comment: 6 figure

Mutational spectrum in a worldwide study of 29,700 families with BRCA1 or BRCA2 mutations.

The prevalence and spectrum of germline mutations in BRCA1 and BRCA2 have been reported in single populations, with the majority of reports focused on White in Europe and North America. The Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) has assembled data on 18,435 families with BRCA1 mutations and 11,351 families with BRCA2 mutations ascertained from 69 centers in 49 countries on six continents. This study comprehensively describes the characteristics of the 1,650 unique BRCA1 and 1,731 unique BRCA2 deleterious (disease-associated) mutations identified in the CIMBA database. We observed substantial variation in mutation type and frequency by geographical region and race/ethnicity. In addition to known founder mutations, mutations of relatively high frequency were identified in specific racial/ethnic or geographic groups that may reflect founder mutations and which could be used in targeted (panel) first pass genotyping for specific populations. Knowledge of the population-specific mutational spectrum in BRCA1 and BRCA2 could inform efficient strategies for genetic testing and may justify a more broad-based oncogenetic testing in some populations