Reflection Component Research Articles

Mapping the circumnuclear regions of the Circinus galaxy with the Imaging X-ray Polarimetry Explorer

ABSTRACT We report on the Imaging X-ray Polarimetry Explorer (IXPE) observation of the closest and X-ray brightest Compton-thick active galactic nucleus (AGN), the Circinus galaxy. We find the source to be significantly polarized in the 2–6 keV band. From previous studies, the X-ray spectrum is known to be dominated by reflection components, both neutral (torus) and ionized (ionization cones). Our analysis indicates that the polarization degree is 28 ± 7 per cent (at 68 per cent confidence level) for the neutral reflector, with a polarization angle of 18° ± 5°, roughly perpendicular to the radio jet. The polarization of the ionized reflection is unconstrained. A comparison with Monte Carlo simulations of the polarization expected from the torus shows that the neutral reflector is consistent with being an equatorial torus with a half-opening angle of 45°–55°. This is the first X-ray polarization detection in a Seyfert galaxy, demonstrating the power of X-ray polarimetry in probing the geometry of the circumnuclear regions of AGNs, and confirming the basic predictions of standard Unification Models.

Chiral liquid crystal based holographic reflective lens for spectral detection.

Flat optics based on chiral liquid crystal (CLC) can be achieved using holographic polarization recording with the help of a photoalignment technique to vary the orientation of the optical axis in a thin CLC layer. A variety of reflective diffractive optical components with high efficiency and polarization selectivity can be realized employing this technique. In this work we discuss the use of CLC diffractive lenses in a spectrometer. The functionalities of two mirrors and a linear grating used in a traditional spectrometer are combined into a single holographic CLC component. Circularly polarized light entering through the slit can be reflected and projected onto a linear detector by the CLC component, with over 90% efficiency. This excellent optical functionality can be achieved with a micrometer thin CLC layer, offering the opportunity for device integration.

Broadband X-Ray Spectral Analysis of the Dual AGN System Mrk 739

We present the result of a broadband (0.5–70 keV) X-ray spectral analysis of the late-merger galaxy Mrk 739, which contains a dual active galactic nucleus (AGN), Mrk 739E and Mrk 739W, with a separation of ≈3.4 kpc. The spectra obtained with NuSTAR, Chandra, XMM-Newton, and Swift/BAT are simultaneously analyzed by separating the contributions from the two AGNs and extended emission with the Chandra data. To evaluate the reflection components from the AGN tori, we consider two models, a phenomenological one (pexrav and zgauss) and a more physically motivated one (XCLUMPY). On the basis of the results with XCLUMPY, we find that the AGNs in Mrk 739E and Mrk 739W have intrinsic 2–10 keV luminosities of 1.0 × 1043 and 7.5 × 1041 erg s−1 absorbed by hydrogen column densities of N H < 6.5 × 1019 cm−2 and , respectively. The torus-covering fraction of the material with N H > 1022cm−2 in Mrk 739E, at a 90% confidence limit, is found to be smaller than those found for late-merger ultra/luminous infrared galaxies, (mean and standard deviation). Considering the small star formation rate of Mrk 739E, we suggest that the gas-to-mass ratio of the host galaxy is an important parameter to determine the circumnuclear environment of an AGN in a late merger.

Impact of ionization and electron density gradients in X-ray reflection spectroscopy measurements

ABSTRACT The models currently used for the analysis of the reflection spectra of black holes usually assume a disc with constant ionization and electron density. However, there is some debate on the impact of these assumptions on the estimate of the properties of the sources, in particular when the fits suggest very steep emissivity profiles in the inner part of the accretion disc. In this work, we re-analyse a selected set of high-quality NuSTAR and Suzaku data of Galactic black holes and we fit the reflection component with three different models: relxill_nk, in which the ionization parameter and the electron density are constant, relxillion_nk, where the electron density is still constant but the ionization profile is described by a power law, and relxilldgrad_nk, where the electron density profile is described by a power law and the ionization profile is calculated self-consistently from the electron density and the emissivity. While relxillion_nk can fit the data better, we do not find any substantial difference in the estimate of the properties of the sources among the three models. Our conclusion is that models with constant electron density and ionization parameter are probably sufficient, in most cases, to fit the currently available X-ray data of accreting black holes.

Cochlear implant imaging in the mouse and guinea pig using light-sheet microscopy

Postmortem examination of the cochlea with a cochlear implant in the scala tympani presents several challenges. It is technologically difficult to section a cochlea with an implant due to the presence of its wires and metal components that are adjacent to the membranous and bony tissues of the cochlea. These metal components damage traditional steel blades of a microtome in celloidin, paraffin or frozen embedded tissues. However, plastic embedded implanted cochleas have been successfully sectioned using specialized methods (Irving et al., 2013). An alternative non-destructive method is to optically section a chemically cleared cochlea using light-sheet microscopy, which we will describe in this publication. However, since this method uses a light-sheet to section the cochlea the opaque and reflective metal components of the implant results in some artifacts in the 2D optical sections. The best image quality using light-sheet fluorescent microscopy is when the implant is removed prior to imaging.

ЕКСТЕРНАЛІЇ УПРАВЛІННЯ РЕФЛЕКСІЄЮ ФІНАНСОВОЇ ТА СОЦІАЛЬНО-ЕКОНОМІЧНОЇ СИСТЕМ

In connection with the growth of innovation management positions, the need to master reflexive methods of introducing innovations into financial and complex socio-economic systems acquires a characteristic role, especially in strategic periods. It was established that in today's turbulent economic conditions, the development of externalities of their management is a prerequisite for the effective functioning of financial and socio-economic systems. The purpose of the article is to identify visible and invisible principles of externality of reflection management of financial and socio-economic systems and to determine the level of readiness of elements of financial and socio-economic systems for the process of innovation. The subject of the study is modern trends in the spread of financial tension, changes in the financial-economic and socio-economic systems, new threats to the spread of externalities of reflection management. The hypothesis of the research is the influence of the consequences of financial and economic deformations on the trends of modifications of the externalities of reflection management at different levels. Methods used in the research: comparison, comparison, systematic and analytical approaches, generalization and classification, dialectical and formal logic. Presenting main material. It was determined that the resource component of innovative reflection is the basis for determining the degree of readiness of the financial and socio-economic systems for the implementation of innovativeness and the formation of strategic management decisions. Approbation and verification of the obtained theoretical conclusions was carried out by conducting a survey of a certain circle of respondents from among the expert environment and the environment of practicing specialists. The main characteristics of the management of innovative reflection of socio-economic systems are revealed: the effectiveness of methods of innovative reflection, the degree of importance of types and forms of reflection for innovative activity, the influence of barriers on the implementation of innovative reflection, the influence of factors on the effectiveness of management of innovative reflection, the influence of the ability to reflect on the success of innovative activity The originality and practical significance of the obtained results lies in the possibility of applying the provided recommendations to improve management and financial control procedures, improve the efficiency of business processes of economic entities in modern conditions. Conclusions. The management of the reflection of financial and socio-economic systems is a multi-level complex of successive management decisions regarding the transformation of management externalities, the formation of an analytical basis for evaluating the reflection of financial and socio-economic systems in order to implement the parameterization of self-development mechanisms of socio-economic systems.

Polarized reflection removal with difference feature attention guidance.

Reflection removal is of great significance for high-level computer vision tasks. Most existing methods separate reflections relying heavily on the quality of intermediate prediction or under certain special constraints. However, these methods ignore the inherent correlation between the background and reflection, which may lead to unsatisfactory results with undesired artifacts. Polarized images contain unique optical characteristics that can facilitate reflection removal. In this paper, we present, to the best of our knowledge, a novel two-stage polarized image reflection removal network with difference feature attention guidance. Specifically, our model takes multi-channel polarized images and Stokes parameters as input and utilizes the optical characteristics of reflected and transmitted light to alleviate the ill-posed nature. It adopts a simple yet effective two-stage structure that first predicts the reflection layer and then refines the transmission layer capitalizing on the special relationship between reflection and transmission light. The difference feature attention guidance module (DFAG) is elaborated to diminish the dependence on intermediate consequences and better suppress reflection. It mitigates the reflection components from the observation and generates the supplement and enhancement to the transmission features. Extensive experiments on the real-world polarized dataset demonstrate the superiority of our method in comparison to the state-of-the-art methods.

Spectral characteristics of the black hole binary 4U 1957+115: a multi mission perspective

ABSTRACT We report spectral analysis of the persistent black hole X-ray binary, 4U 1957+115, using AstroSat, Swift, and NuSTAR observations carried out between 2016 and 2019. Modelling with a disc emission, thermal Comptonization, and blurred reflection components revealed that the source was in the high-soft state with the disc flux ∼87 per cent of the total and high-energy photon index ∼2.6. There is an evidence that either the inner disc radius varied by ∼25 per cent or the colour hardening factor changed by ∼12 per cent. The values of the inner disc radius imply that for a non-spinning black hole, the black hole mass is &amp;lt; 7 M ⊙ and the source is located &amp;gt; 30 kpc away. On the other hand, a rapidly spinning black hole would be consistent with the more plausible black hole mass of &amp;lt; 10 M ⊙ and a source distance of ∼10 kpc. Fixing the distance to 10 kpc and using a relativistic accretion disc model, constrained the black hole mass to 6 M⊙ and inclination angle to 72°. A positive correlation is detected between the accretion rate and inner radii or equivalently between the accretion rate and colour factor.

An analysis of educational innovation culture by a Delphi expert panel

This paper aims to reflect on educational innovation from the point of view of its representation as an indispensable element within the pedagogical culture of educational centers. We present the current elements that constitute the definition of educational innovation, its dimensions, obstacles, and determining factors that will delimit the institutionalization of the innovation process in education. To achieve this aim, we applied the Delphi technique and formulated questions whose answers were agreed upon in several iterations by 20 experts. The results have been organized into four categories that provide the backbone features of the visions, paradigms, opinions, and relevant pedagogical reflections on the concept of innovation, on the organization and participants in the process of innovation, on the pressures and resistance encountered during the process, and on the promotion and trends of educational innovation. We conclude that the definition of educational innovation requires a reflective yet critical and transformative component and that there is a close relationship between innovation and leadership in educational centers. We highlight the lack of time and weak training as the main factors limiting the implementation of reflective and transformative educational innovation processes. Finally, we highlight that promoting an educational innovation culture should be based on flexible research and evaluation processes that enable decision-making and favor pedagogical beliefs for change, together with continuous collaborative support.

Psychological Conditions for the Effectiveness of Distance Education

The article deals with psychological conditions impacting distance education in high school. Information on the specifics of the use of distance educational technologies is analysed. Special attention was paid to motivation and reflection. Following methods were used: psychological and formative pedagogical experiment, testing, observation, analysis of percentage trends, Student’s t-test. The independent variable of the experiment is motivational exercises and reflective reports of distance courses, and the dependent variable is professional competence of the research participants. The domination of the medium indicators of motivational, cognitive, operational-activity, reflective components of professional competence of students was revealed. The students’ ability to carry out self-analysis is the least developed. A formative experiment conducted in the control group revealed a shift in cognitive and operational-activity components. Positive dynamics was found for all studied parameters in the experimental group, which used motivational exercises and reflective reports. The calculation of Student’s t-test confirmed significance of all detected transformations. The study proves the importance of creating psychological conditions to improve the effectiveness of distance education. We see the possibility of improving the developed methodology in the individualization of psychological assignments. The results of the study can be used as a basis for specialized psychological training programmes for the teachers who deliver distance learning courses. Further prospects for the research on the problem are studying the impact of the psychological state of teachers on the effectiveness of distance education, as well as comparing the results of the introduction of certain psychological conditions in traditional and distance learning.

The spectral-timing analysis of Cygnus X-1 with Insight-HXMT

Cygnus X-1, as the first discovered black hole binary, is a key source for understanding the mechanisms of state transitions and the scenarios of accretion in extreme gravity fields. We present a spectral-timing analysis of observations taken with the Insight–Hard X-ray Modulation Telescope (HXMT) mission, focusing on the spectral-state-dependent timing properties in the broad energy range of 1−150 keV, thus extending previous studies based on Rossi X-ray Timing Explorer (RXTE) to both lower and higher energies. Our main results are the following: (a) We successfully use a simple empirical model to fit all spectra, confirming that the reflection component is stronger in the soft state than in the hard state. (b) The evolution of the total fractional root mean square (rms) depends on the selected energy band and the spectral shape, which is a direct result of the evolution of the power spectral densities (PSDs). (c) In the hard/intermediate state, we see clear short-term variability features and a positive correlation between the central frequencies of the variability components and the soft photon index Γ1, which we also see at energies above 15 keV. In the soft state, the power spectrum is instead dominated by red noise. These behaviors can be traced to at least 90 keV. (d) Finally, the coherence and the phase-lag spectra show different behaviors, depending on the different spectral shapes.

Unsupervised Decomposition and Correction Network for Low-Light Image Enhancement

Vision-based intelligent driving assistance systems and transportation systems can be improved by enhancing the visibility of the scenes captured in extremely challenging conditions. In particular, many low-image image enhancement (LIE) algorithms have been proposed to facilitate such applications in low-light conditions. While deep learning-based methods have achieved substantial success in this field, most of them require paired training data, which is difficult to be collected. This paper advocates a novel Unsupervised Decomposition and Correction Network (UDCN) for LIE without depending on paired data for training. Inspired by the Retinex model, our method first decomposes images into illumination and reflectance components with an image decomposition network (IDN). Then, the decomposed illumination is processed by an illumination correction network (ICN) and fused with the reflectance to generate a primary enhanced result. In contrast with fully supervised learning approaches, UDCN is an unsupervised one which is trained only with low-light images and corresponding histogram equalized (HE) counterparts (can be derived from the low-light image itself) as input. Both the decomposition and correction networks are optimized under the guidance of hybrid no-reference quality-aware losses and inter-consistency constraints between the low-light image and its HE counterpart. In addition, we also utilize an unsupervised noise removal network (NRN) to remove the noise previously hidden in the darkness for further improving the primary result. Qualitative and quantitative comparison results are reported to demonstrate the efficacy of UDCN and its superiority over several representative alternatives in the literature. The results and code will be made public available at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://github.com/myd945/UDCN</uri> .

Black hole mass estimation using X-ray variability measurements in Seyfert galaxies

Aims. Our objective is to critically assess the X-ray flux variability as a tool for measuring the black hole (BH) mass in active galactic nuclei (AGN). We aim to establish a prescription for estimating BH masses based on measurements of the normalised excess variance from X-ray data. We discuss the minimum requirements in terms of the light-curve duration and X-ray signal-to-noise ratio (S/N) to enable a reliable determination that is comparable to what can be derived from the continuum and emission line reverberation studies. Methods. We used the light curves of local Seyfert from the Nuclear Spectroscopic Telescope Array hard X-ray mission (NuSTAR), to compute the normalised excess variance (σNXV2) in the 3–10 and 10–20 keV bands, thus extending the analysis to an energy band higher than 10 keV. The excess variance measurements were then combined with independent BH mass estimates from the literature to establish the MBH vs. σNXV2 relation for different samples and weigh its accuracy in terms of the light-curve duration and X-ray S/N. Results. We find that it is possible to accurately measure the BH mass in AGN using excess variance measurements in the 3–10 and the 10–20 keV bands, however, strong quality requirements should be applied. The minimum necessary S/N and duration of the light curves used to compute the excess variance ought to be ∼3 and ∼80 − 100 ks, respectively. We provide a linear relationship between the normalised excess variance and the black hole mass that can be used to estimate the latter, with an average uncertainty of the order of 0.4 − 0.25 dex (depending on the adopted light-curve segment duration). In general, BH mass estimates from 3–10 keV and 10–20 keV band light curves are expected to be similar. The 10–20 keV band is preferred for sources that are heavily absorbed and the 3–10 keV band is preferred for sources that may be dominated by the X-ray reflection component at energies above 10 keV.

Polarization Analysis of Trihedral Corner Reflector With High-Frequency Approximation

Due to that the polarization scattering matrices (PSM) of single reflection (SR), double reflection (DR), and single diffraction (SD) at different angles are ignored, the PSM of trihedral corner reflector (TCR) is usually assumed to be [1 0; 0 1], which results in inaccuracy by utilizing its polarization to antijamming. Therefore, this article comprehensively analyzes the PSM of TCR based on high-frequency approximation. First, we separately analyze various reflection components based on the physical optics (PO)-shooting bouncing ray (SBR) model, so as to cure the deficiency that the classification discussion methods are susceptible to changes in target size and shape. Then, the PSMs of SR, DR, triple reflection, and SD are rigorously deduced and demonstrated by combining amplitude/phase information. In this process, we successfully integrate the six kinds of DR by the transforming of polarization base. Subsequently, the PSMs in the 2-D space are extended into the 3-D space, which are more suitable for the polarization characteristics of TCR. Finally, we compare the model in this article with the method of moment (MoM) of Feko software and obviously accelerate the model in this article through compute unified device architecture (CUDA). The conclusion of this article is significant for the polarization analysis of TCR to antijamming.

Robust contrast enhancement method using a retinex model with adaptive brightness for detection applications.

Low light image enhancement with adaptive brightness, color and contrast preservation in degraded visual conditions (e.g., extreme dark background, lowlight, back-light, mist. etc.) is becoming more challenging for machine cognition applications than anticipated. A realistic image enhancement framework should preserve brightness and contrast in robust scenarios. The extant direct enhancement methods amplify objectionable structure and texture artifacts, whereas network-based enhancement approaches are based on paired or large-scale training datasets, raising fundamental concerns about their real-world applicability. This paper presents a new framework to get deep into darkness in degraded visual conditions following the fundamental of retinex-based image decomposition. We separate the reflection and illumination components to perform independent weighted enhancement operations on each component to preserve the visual details with a balance of brightness and contrast. A comprehensive weighting strategy is proposed to constrain image decomposition while disrupting the irregularities of high frequency reflection and illumination to improve the contrast. At the same time, we propose to guide the illumination component with a high-frequency component for structure and texture preservation in degraded visual conditions. Unlike existing approaches, the proposed method works regardless of the training data type (i.e., low light, normal light, or normal and low light pairs). A deep into darkness network (D2D-Net) is proposed to maintain the visual balance of smoothness without compromising the image quality. We conduct extensive experiments to demonstrate the superiority of the proposed enhancement. We test the performance of our method for object detection tasks in extremely dark scenarios. Experimental results demonstrate that our method maintains the balance of visual smoothness, making it more viable for future interactive visual applications.

INFORMATION TECHNOLOGY COMPETENCE AS A STRUCTURE-FORMING COMPONENT OF THE TRAINING OF FORESTRY SPECIALISTS

The article reveals the essence and component composition of informatics-technological competence as a structural component of the training of forestry specialists. The types of professional activity of forestry specialists are established: production-technological, organizational-management, scientific-research, design-construction. The specifics of the forestry engineer's professional activity are revealed. Based on the analysis of scientific sources, definitions of the concepts: "competence", "professional competence", "types of competence", "information", "technology", "information technology activity of a forestry engineer" "information technology competence of a forestry engineer" are given. Basic competencies are distinguished in the structure of professional competence of a forestry engineer: special, project-research, environmental, organizational-communicative, individual, informatics-technological. The specifics of the conditions for the implementation of production processes in the forestry industry are considered. Approaches to the concept of "informatics and technological competence" are revealed. The first of them characterizes the ability to use software and communication means of information processing (in this case, technology means a set of technical and hardware tools (computer equipment, communication lines, telecommunications devices, etc., which provides this process). The second approach is based on the application means of information and communication technologies in the professional activity of a specialist to solve production tasks (technology means a certain sphere of human activity).&#x0D; In the structure of informatics-technological competence, motivational-value, cognitive, functional-activity and reflexive components are distinguished. The motivational-value component consists of motives and value attitudes, which are characterized by personal interest in working with information sources, determine the need to study computer technologies from the point of view of their application in professional activities, and determine the motivated focus of the specialist on functioning in the conditions of the information environment. The cognitive component includes a set of such theoretical knowledge that reflects the intellectual development of the individual, such as an understanding of the unity and integrity of the scientific picture of the world, the presence of a system of methodological knowledge and categories, the ability to establish intra- and inter-subject connections regarding various scientific concepts and methods, etc. The functional-activity component, being aimed at the practical use of the acquired knowledge, reflects the active, active nature of competence and is a set of knowledge, abilities and skills necessary for independent implementation of information technology activities. The reflective component allows the individual to consider and adequately evaluate the results of the activity, showing the ability to consciously and independently implement and regulate the level of control of one's own development and personal achievements. Coordination of components with professionally important qualities of a specialist was carried out.

PENINGKATAN EFEKTIVITAS DAN HASIL BELAJAR PENDIDIKAN JASMANI, OLAHRAGA DAN KESEHATAN MELALUI PENERAPAN APLIKASI GOOGLE CLASSROOM SISWA KELAS VIII-C SMP NEGERI 6 MATARAM TAHUN PELAJARAN 2021/2022

The purpose of this study was to determine: the application of the Google Classroom application in increasing the effectiveness of learning PJOK in class VIII-C students of SMP Negeri 6 Mataram in the 2021/2022 academic year.The study used a classroom action research design that included the components of planning, action, observation and reflection, by taking the subjects of class VIIIC students of SMP Negeri 6 Mataram as many as 35 people consisting of 24 boys and 11 girls. The data were analyzed with Learning Management, learning effectiveness and student learning outcomes.The results show that: the application of the Google Classroom application can increase the effectiveness of learning PJOK in class VIII-C students of SMP Negeri 6 Mataram in the 2021/2022 academic year

Cassini Bistatic Radar Experiments: Preliminary Results on Titan’s Polar Regions

In bistatic radar observations, reflected echoes from the surface of a target planet can be analyzed to infer its surface statistics and near-surface constituents. In this work, a preliminary inspection of two X-band bistatic radar observations gathered by the Cassini spacecraft about Titan’s polar regions is presented. Profiles of relative dielectric constant and root-mean-square (rms) surface slope are provided as outputs of the analysis, discussed, and compared with the present knowledge of Titan geomorphology. For the assessment of the rms slope, proportional to the spectral broadening of reflected echoes, a basic fitting procedure was applied to the received spectra using a Gaussian template, to later evaluate the full-width half-maximum of the fitting curve. The dielectric constant was computed from the power ratio between orthogonally circularly polarized components of signal reflections from Titan. Dielectric constant estimates are, on average, consistent with the expected materials covering the dry surfaces of the planet, while slightly low values were found over the seas. The rms slopes are generally low compared to past bistatic observations of other targets. Titan’s north polar seas are revealed to feature an unprecedented smoothness, with 0.01^circ of slope as an upper bound. Similar values were inferred for isolated spots in the southern pole, hinting at the possible presence of basins filled with liquid hydrocarbons. The main issues with the analysis are emphasized throughout the document, and some ideas for future work are presented in the conclusions.

The Use of Information Technology in the Educational Process during Martial Law

The aim of the article was to evaluate the effectiveness of emotional support in the introduction of information technology in higher educational institutions during martial law. The following methods were used: general theoretical; testing, analysis of products of activity, formative experiment, statistical methods. Motivational, cognitive, activity and reflective components of professional competence were identified in the course of theoretical analysis. The medium indicators of dominance of cognitive, activity and reflective components of professional competence of students during martial law were recorded. The motivational component was the least developed. Experimental impact is effective for the development of motivational and cognitive components, but requires further clarification in the development of activity and reflective components. The significance of the changes is confirmed by statistical verification of the data. Prospects for research on the problem involve expanding the number and duration of research on the use of educational information technology during martial law.

Optical spectra of zigzag graphene nanoribbons: a first-principles study

The electrical and optical properties of zigzag graphene nanoribbons is simulated using Density Functional Theory (DFT). It is found that n-ZGNRs (n = 18, 22, 26, 30) have metallic behavior. The results reveal that when the nanoribbon width increases, the first optical bandgap and optical absorption peaks diminish. Furthermore, at energies greater than around 1.40 eV, n-ZGNRs (n = 18, 22, 26, 30) have a negative refractive index for the z polarization. The maximum optical reflection peaks of n-ZGNRs (n = 18, 22, 26, 30) occur at about 5 eV for y polarization. Furthermore, unlike the y polarization, the z components of optical reflectivity are positioned at lower energies. The results show that the optical extinction of the simulated ZGNRs increases with ribbon width. The main reason is that the larger supercells have a higher mass density. For ∼ 0–4.50 eV, n-ZGNRs (n = 18, 22, 26, 30) support the conditions for the transverse-electric (TE) mode. Additionally, for higher than around 4.50 eV, n-ZGNRs (n = 18, 22, 26, 30) supplies the transverse-magnetic (TM) plasmons.