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Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2384
Author(s):  
Riccardo Sturani

While being as old as general relativity itself, the gravitational two-body problem has never been under so intense investigation as it is today, spurred by both phenomenological and theoretical motivations. The observations of gravitational waves emitted by compact binary coalescences bear the imprint of the source dynamics, and as the sensitivity of detectors improve over years, more accurate modeling is being required. The analytic modeling of classical gravitational dynamics has been enriched in this century by powerful methods borrowed from field theory. Despite being originally developed in the context of fundamental particle quantum scatterings, their applications to classical, bound system problems have shown that many features usually associated with quantum field theory, such as, e.g., divergences and counterterms, renormalization group, loop expansion, and Feynman diagrams, have only to do with field theory, be it quantum or classical. The aim of this work is to present an overview of this approach, which models massive astrophysical objects as nonrelativistic particles and their gravitational interactions via classical field theory, being well aware that while the introductory material in the present article is meant to represent a solid background for newcomers in the field, the results reviewed here will soon become obsolete, as this field is undergoing rapid development.


Stats ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 578-594
Author(s):  
Frank Benford

A random variable X that is base b Benford will not in general be base c Benford when c≠b. This paper builds on two of my earlier papers and is an attempt to cast some light on the issue of base dependence. Following some introductory material, the “Benford spectrum” of a positive random variable is introduced and known analytic results about Benford spectra are summarized. Some standard machinery for a “Benford analysis” is introduced and combined with my method of “seed functions” to yield tools to analyze the base c Benford properties of a base b Benford random variable. Examples are generated by applying these general methods to several families of Benford random variables. Berger and Hill’s concept of “base-invariant significant digits” is discussed. Some potential extensions are sketched.


Author(s):  
Frank Benford

A random variable X that is base b Benford will not in general be base c Benford when c is not equal to b. This paper builds on two of my earlier papers and is an attempt to cast some light on the issue of base dependence. Following some introductory material, the “Benford spectrum” of a positive random variable is introduced and known analytic results about Benford spectra are summarized. Some standard machinery for a “Benford analysis” is introduced and combined with my method of “seed functions” to yield tools to analyze the base c Benford properties of a base b Benford random variable. Examples are generated by applying these general methods to several families of Benford random variables. Berger and Hill's concept of “base-invariant significant digits” is discussed. Some potential extensions are sketched.


2021 ◽  
Vol 6 (1) ◽  
pp. 39-45
Author(s):  
Volodymyr Pavlenko ◽  
◽  
Oksana Lashko

This paper considers the problem of developing specialized software designed to support small businesses. It substantiates the relevance of creating such systems; architecture has been offered; and the results of development have been given. For practical use, a specific subject area has been considered, which allows to clearly understand the purpose and outcome of the work. These materials can be used to obtain ready-made solutions during the development of a software package on this topic. This document can be considered as an introductory material for the various stages of the project to develop a system of effective support of small business.


Polymers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 155
Author(s):  
Ali Aldalbahi ◽  
Mehrez E. El-Naggar ◽  
Mohamed H. El-Newehy ◽  
Mostafizur Rahaman ◽  
Mohammad Rafe Hatshan ◽  
...  

Textile manufacturing has been one of the highest polluting industrial sectors. It represents about one-fifth of worldwide industrial water pollution. It uses a huge number of chemicals, numerous of which are carcinogenic. The textile industry releases many harmful chemicals, such as heavy metals and formaldehyde, into water streams and soil, as well as toxic gases such as suspended particulate matter and sulphur dioxide to air. These hazardous wastes, may cause diseases and severe problems to human health such as respiratory and heart diseases. Pollution caused by the worldwide textile manufacturing units results in unimaginable harm, such as textile polymers, auxiliaries and dyes, to the environment. This review presents a systematic and comprehensive survey of all recently produced high-performance textiles; and will therefore assist a deeper understanding of technical textiles providing a bridge between manufacturer and end-user. Moreover, the achievements in advanced applications of textile material will be extensively studied. Many classes of technical textiles were proved in a variety of applications of different fields. The introductory material- and process-correlated identifications regarding raw materials and their transformation into yarns, fibers and fabrics followed by dyeing, printing, finishing of technical textiles and their further processing will be explored. Thus, the environmental impacts of technical textiles on soil, air and water are discussed.


2021 ◽  
Author(s):  
Steven Stephenson

Neither plants, nor animals, nor fungi, the myxomycetes are a surprisingly diverse and fascinating group of organisms. They spend the majority of their life out of sight as single-celled amoeboid individuals in leaf litter, soil or decaying wood, foraging for bacteria and other simple life forms. However, when conditions are right, two individual cells come together to give rise to a much larger, creeping structure called a plasmodium, which produces the even more complex and often beautiful fruiting bodies. Indeed, the fruiting bodies of myxomycetes are often miniature works of art! Their small size (usually only a few millimetres tall) and fleeting fruiting phase mean that these organisms, although ubiquitous and sometimes abundant, are overlooked by most people. However, recent research by a few dedicated individuals has shown that Australia has a very diverse myxomycete biota with more than 330 species, the largest number known for any region of the Southern Hemisphere. This comprehensive monograph provides keys, descriptions and information on the known distribution for all of these species in addition to containing introductory material relating to their biology and ecology. Many species are illustrated, showing the diversity of their fruiting bodies, and greatly facilitating their identification. This book will give naturalists a new insight into an often overlooked group of organisms in addition to providing an incentive to search for the many species which have undoubtedly thus far escaped notice.


2020 ◽  
Vol 11 (3) ◽  
pp. 307-324
Author(s):  
Maggie Grant ◽  
Karen Lury

This article explores the use of digital images as part of the adoption process. Based on a series of semi-structured interviews with adoptive parents, social workers and foster carers, it explores the responses of these stakeholders and reflects on the value and effect of digital images as they are employed when a child is placed for adoption. The research reveals how the kinds of information ‘moving images’ can offer become significant, not just as introductory material for potential adoptive parents – operating within the in-between space for the parent waiting to adopt and the child waiting to be placed – but as facilitating a virtual, present-tense dialogue (in-between adopters, foster carers and the child) once a placement has been agreed. Another unanticipated revelation was the extent to which clips were valued beyond their instrumental use in these in-between spaces and resonated within the future life narrative of the adopted child.


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