scholarly journals Deep Bayesian local crystallography

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Sergei V. Kalinin ◽  
Mark P. Oxley ◽  
Mani Valleti ◽  
Junjie Zhang ◽  
Raphael P. Hermann ◽  
...  

AbstractThe advent of high-resolution electron and scanning probe microscopy imaging has opened the floodgates for acquiring atomically resolved images of bulk materials, 2D materials, and surfaces. This plethora of data contains an immense volume of information on materials structures, structural distortions, and physical functionalities. Harnessing this knowledge regarding local physical phenomena necessitates the development of the mathematical frameworks for extraction of relevant information. However, the analysis of atomically resolved images is often based on the adaptation of concepts from macroscopic physics, notably translational and point group symmetries and symmetry lowering phenomena. Here, we explore the bottom-up definition of structural units and symmetry in atomically resolved data using a Bayesian framework. We demonstrate the need for a Bayesian definition of symmetry using a simple toy model and demonstrate how this definition can be extended to the experimental data using deep learning networks in a Bayesian setting, namely rotationally invariant variational autoencoders.

Author(s):  
Rob. W. Glaisher ◽  
A.E.C. Spargo

Images of <11> oriented crystals with diamond structure (i.e. C,Si,Ge) are dominated by white spot contrast which, depending on thickness and defocus, can correspond to either atom-pair columns or tunnel sites. Olsen and Spence have demonstrated a method for identifying the correspondence which involves the assumed structure of a stacking fault and the preservation of point-group symmetries by correctly aligned and stigmated images. For an intrinsic stacking fault, a two-fold axis lies on a row of atoms (not tunnels) and the contrast (black/white) of the atoms is that of the {111} fringe containing the two-fold axis. The breakdown of Friedel's law renders this technique unsuitable for the related, but non-centrosymmetric binary compound sphalerite materials (e.g. GaAs, InP, CdTe). Under dynamical scattering conditions, Bijvoet related reflections (e.g. (111)/(111)) rapidly acquire relative phase differences deviating markedly from thin-crystal (kinematic) values, which alter the apparent location of the symmetry elements needed to identify the defect.


2021 ◽  
Vol 13 (8) ◽  
pp. 4186
Author(s):  
Abdulhakeem Raji ◽  
Abeer Hassan

This paper adopted a case study approach to investigate the sustainability practices of a Scottish university in order to understand if sustainability forms part of its central policy agenda. As such, the paper focuses on the levels of awareness and disclosure of their sustainable practices, measuring the impacts and effectiveness of those initiatives. This paper introduces signaling theory to explore the idea that appropriate communication via integrated thinking can close the gap between the organization and its stakeholders. We believe that the provision of this relevant information will lead to better communication between the organization and its stakeholders, supporting a signaling theory interpretation. Therefore, we are suggesting that integrated thinking is an internal process that organizations can follow to increase the level of disclosure as a communication tool with stakeholders. From the literature reviewed, four themes were identified (definition of university sustainability, sustainability awareness, disclosure framework within universities, and level of accountability). The research adopted a pragmatic view and conducted individual interviews with participants belonging to three stakeholder groups (members of the university’s senior management, the governing council, and the student union executive). Although this study focused on just one Scottish university, it should still provide some insight for the better understanding of the underpinning issues surrounding the sustainability accountability practices of Scottish universities in general. The research findings indicated that the university prioritized only two sustainability dimensions—economic and environmental—and that the university still perceived sustainability as a voluntary exercise. Additionally, it is evident that the university had no framework in place for measuring its sustainability delivery—and therefore had no established medium of communicating these activities to its stakeholders. Moreover, research findings showed that the social and educational context of sustainability was lacking at the university. The university has done little or nothing to educate its stakeholders on sustainability.


2021 ◽  
Vol 11 (2) ◽  
pp. 790
Author(s):  
Pablo Venegas ◽  
Rubén Usamentiaga ◽  
Juan Perán ◽  
Idurre Sáez de Ocáriz

Infrared thermography is a widely used technology that has been successfully applied to many and varied applications. These applications include the use as a non-destructive testing tool to assess the integrity state of materials. The current level of development of this application is high and its effectiveness is widely verified. There are application protocols and methodologies that have demonstrated a high capacity to extract relevant information from the captured thermal signals and guarantee the detection of anomalies in the inspected materials. However, there is still room for improvement in certain aspects, such as the increase of the detection capacity and the definition of a detailed characterization procedure of indications, that must be investigated further to reduce uncertainties and optimize this technology. In this work, an innovative thermographic data analysis methodology is proposed that extracts a greater amount of information from the recorded sequences by applying advanced processing techniques to the results. The extracted information is synthesized into three channels that may be represented through real color images and processed by quaternion algebra techniques to improve the detection level and facilitate the classification of defects. To validate the proposed methodology, synthetic data and actual experimental sequences have been analyzed. Seven different definitions of signal-to-noise ratio (SNR) have been used to assess the increment in the detection capacity, and a generalized application procedure has been proposed to extend their use to color images. The results verify the capacity of this methodology, showing significant increments in the SNR compared to conventional processing techniques in thermographic NDT.


Entropy ◽  
2018 ◽  
Vol 20 (7) ◽  
pp. 541 ◽  
Author(s):  
Venkata Kota ◽  
Narendra Chavda

Embedded ensembles or random matrix ensembles generated by k-body interactions acting in many-particle spaces are now well established to be paradigmatic models for many-body chaos and thermalization in isolated finite quantum (fermion or boson) systems. In this article, briefly discussed are (i) various embedded ensembles with Lie algebraic symmetries for fermion and boson systems and their extensions (for Majorana fermions, with point group symmetries etc.); (ii) results generated by these ensembles for various aspects of chaos, thermalization and statistical relaxation, including the role of q-hermite polynomials in k-body ensembles; and (iii) analyses of numerical and experimental data for level fluctuations for trapped boson systems and results for statistical relaxation and decoherence in these systems with close relations to results from embedded ensembles.


2014 ◽  
Vol 9 ◽  
Author(s):  
Roberto Tramarin ◽  
Mario Polverino ◽  
Maurizio Volterrani ◽  
Bruna Girardi ◽  
Claudio Chimini ◽  
...  

Background: Cardiovascular and respiratory diseases are leading causes of morbidity and their co-occurrence has important implications in mortality and other outcomes. Even the most recent guidelines do not reliably address clinical, prognostic, and therapeutic concerns due to the overlap of respiratory and cardiac diseases. Study objectives and design: In order to evaluate in the reality of clinical practice the epidemiology and the reciprocal impact of cardio-pulmonary comorbidity on the clinical management, diagnostic workup and treatment, 1,500 cardiac and 1,500 respiratory inpatients, admitted in acute and rehabilitation units, will be enrolled in a multicenter, nationwide, prospective observational study. For this purpose, each center will enroll at least 50 consecutive patients. At discharge, data analysis will be aimed at the definition of cardiac and pulmonary inpatient comorbidity prevalence, demographic characteristics, length of hospital stay, and risk factors, taking into account also procedures, pharmacological and non-pharmacological treatment, and follow up in patients with cardio-respiratory comorbidity. Conclusions: The purely observational design of the study aims to give new relevant information on the assessment and management of overlapping patients in real life clinical practice, and new insight for improvement and implementation of current guidelines on the management of individual diseases.


2017 ◽  
Author(s):  
Chad Nilep

This paper reviews a brief portion of the literature on code switching in sociology, linguistic anthropology, and sociolinguistics, and suggests a definition of the term for sociocultural analysis. Code switching is defined as the practice of selecting or altering linguistic elements so as to contextualize talk in interaction. This contextualization may relate to local discourse practices, such as turn selection or various forms of bracketing, or it may make relevant information beyond the current exchange, including knowledge of society and diverse identities.


Author(s):  
Diêgo Andrade de Oliveira ◽  
Rosângela Souza Lessa ◽  
Suzana Cristina Silva Ribeiro ◽  
Pedro Fonseca de Vasconcelos

Abstract: Introduction: In the context of medical school, the development of methodologies that stimulate the students’ search for learning, autonomy and creativity are essential for medical education in Brazil. The study aims to describe the construction of infographics as a pedagogical proposal for the learning of organic human aging processes by medical students. Method: Medical students attending the 4th period at a Higher Education Institution built infographics, as a requirement for the practical content of the Aging Process module. The static-type infographic was adopted, following criteria such as the definition of the target audience; definition of the objective; choice of topic; selection of the most relevant information (focus); direct and accessible language; organized information; choices of color palettes and style and; infographic sketch. The entire creation process was supervised by the teacher in charge of the project, and evaluation criteria were previously established. Results: The class was divided into seven groups, resulting in the production of an infographic with a specific topic per group. The human aging topics were: Degenerative Joint Diseases, Bone Weakness, Pneumonia in the Elderly, Acute Myocardial Infarction, Vascular Dementia, Atherosclerosis and Herpes Zoster. It is worth noting that in addition to the creation, each group presented the final product to the other colleagues, explaining each item included in the static infographic. Conclusions: We observed that the students satisfactorily met the proposed evaluation requirements, demonstrating their involvement in the construction of infographics and, above all, in simple, creative and objective learning, using a powerful visual tool. We also add that the printed material will be used as aid in the histology laboratory and in extramural activities.


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