scholarly journals Physical methods for investigating structural colours in biological systems

Author(s):  
P Vukusic ◽  
D.G Stavenga

Many biological systems are known to use structural colour effects to generate aspects of their appearance and visibility. The study of these phenomena has informed an eclectic group of fields ranging, for example, from evolutionary processes in behavioural biology to micro-optical devices in technologically engineered systems. However, biological photonic systems are invariably structurally and often compositionally more elaborate than most synthetically fabricated photonic systems. For this reason, an appropriate gamut of physical methods and investigative techniques must be applied correctly so that the systems' photonic behaviour may be appropriately understood. Here, we survey a broad range of the most commonly implemented, successfully used and recently innovated physical methods. We discuss the costs and benefits of various spectrometric methods and instruments, namely scatterometers, microspectrophotometers, fibre-optic-connected photodiode array spectrometers and integrating spheres. We then discuss the role of the materials' refractive index and several of the more commonly used theoretical approaches. Finally, we describe the recent developments in the research field of photonic crystals and the implications for the further study of structural coloration in animals.

2019 ◽  
Vol 41 (3) ◽  
pp. 204-215
Author(s):  
Halina Grzymała-Moszczyńska ◽  
Maria Kanal

The goal of our article is to present the subject of forced migration as a very interesting and socially relevant research field that could contribute to further development of the psychology of religion. We focus on further development of the toolbox of the psychology of religion, seeking further application of Sunden’s role theory and introducing new approaches originating from indigenous and environmental psychology. After a short review of existing research, new theoretical approaches, and methodologies are presented, along with suggestions for improving the validity of qualitative research pertaining to the role of religion at all stages of the migration process.


2021 ◽  
Author(s):  
Kai Uwe Totsche ◽  
Ingrid Kögel-Knabner ◽  

<p>Microaggregate development and turnover and its linkage to the function of soils is a major research field in soil science. Microaggregates are deemed the most stable and persistent compound structures in soils and are conceptually considered as the fundamental structural building units of a – frequently even hierarchically structured – soil (Totsche et al. 2018). Most of the research on microaggregates has been motivated by the search for a better understanding of the storage and dynamics of soil organic matter. Fueled by the advent of instrumental analytical tools that allow to study soil structural and chemical heterogeneity, biodiversity and biogeography on the submicron scale, and expedited by the advancement of theoretical approaches for joint reconstruction and interpretation in-silico  recent direction changed: New foci are the formation, stability and turnover of microaggregates, their composite building units, the patterns of spatial allocation of the various inorganic, organic and biotic materials involved, and the role microaggregates might have in and for the functioning of soil. This presentation will give a compact overview on the current topics, challenges and concepts in microaggregate research and the role of microaggregates for the architecture, properties and functions of soils.</p>


2021 ◽  
Author(s):  
Devesh Bhasin ◽  
David Staack ◽  
Daniel A. McAdams

Abstract This work analyzes the role of bioinspired product architecture in facilitating the development of robust engineering systems. Existing studies on bioinspired product architecture largely focus on inspiring biology-like function-sharing in engineering design. This work shows that the guidelines for bioinspired product architecture, originally developed for bioinspiration of function-sharing, may induce robustness to random failures in engineered systems. To quantify such an improvement, this study utilizes Functional Modeling to derive modular equivalents of biological systems. The application of the bioinspired product architecture guidelines is then modeled as a transition from the modular product architecture of the modular equivalents to the actual product architecture of the biological systems. The robustness of the systems to random failures is analyzed after the application of each guideline by modeling the systems as directed networks. A singular robustness metric is then introduced to quantify the degradation in the expected functionality of systems upon increasing severity of random disruptions. Our results show that a system with bioinspired product architecture exhibits a gradual degradation in expected functionality upon increasing the number of failed modules as compared to an equivalent system with a one-to-one mapping of functions to modules. The findings are validated by designing and analyzing a COVID-19 breathalyzer as a case study.


2013 ◽  
Vol 24 (1) ◽  
pp. 47-69
Author(s):  
Finn Kenneth Hansen ◽  
M. Azhar Hussain

Hvordan måler man fattigdom forstået, som det ikke at kunne klare sig selv, i det samfund man lever i? Fattigdomsopgørelser er ofte baseret på indkomst, som siger noget om mulighederne, men ikke noget om faktisk levevis. Der er derfor behov for metoder, som mere direkte belyser, hvad det vil sige ikke at kunne klare sig selv. I den sammenhæng har fattigdomsforskere peget på konsekvenser i form af afsavn. Den engelske fattigdomsforsker Peter Townsend var banebrydende inden for området. Artiklen sætter fokus på afsavnsbegrebet, dets oprindelse, anvendelse og udbredelse og peger på metodiske problemer ved afsavnsopgørelser. Det diskuteres, om der findes et indkomstniveau, under hvilket afsavnene er væsentligt mere omfattende end over dette indkomstniveau – altså findes knækket (kink), eller er der snarere tale om et missing link mellem afsavn og økonomisk levestandard? Afsavnstilgangens anvendelighed i Danmark, EU og globalt, samt over tid problematiseres. Den seneste udvikling i teoretiske bidrag til opgørelse af flere samtidige afsavn præsenteres, herunder Foster & Alkires multidimensionale mål for fattigdom og Arndt et al.s first order dominance-kriterie. Endelig illustreres afsavnstilgangen dels ved at se på afsavn blandt modtagere af de laveste sociale ydelser sammenlignet med andre forsørgelsesgrupper og dels ved en præsentation af afsavn i en EU-sammenhæng. ENGELSK ABSTRACT: Finn Kenneth Hansen and M. Azhar Hussain: Deprivation: Calculating the Extent of Poverty Poverty is often based on income, which says something about the possibilities of providing for oneself, but nothing about real living conditions. Therefore we need methods to measure more precisely what it means to not be able to provide for oneself. To do so, poverty researchers have identified the consequences of poverty in terms of deprivation. Peter Townsend has been the leading scholar in this research field. This article focuses on the concept of deprivation, its origin, use and dissemination, and also points out the methodological problems of measuring deprivation. One of the debates is whether there is an income level below which deprivation is almost absolute – or whether there is a missing link between deprivation and income. The article analyses the deprivation approach in Denmark, EU and globally, and over time. Recent developments in theoretical contributions to the compilation of multiple deprivation measures are presented, including Foster & Alkire’s multidimensional poverty measure and Arndt et al.’s first order dominance criterion. Finally, we analyze deprivation among recipients of the lowest benefits in Denmark as compared to other groups in the country employing these theoretical approaches, and then present deprivation in an EU context. Key words: Poverty, deprivation, methodology, multidimensional, EU.


2013 ◽  
Vol 284-287 ◽  
pp. 645-651
Author(s):  
Zhi Jie Li ◽  
Su Jun Dong

This article reviews how the constructal law governs the design and evolution of flow configuration in nature and engineering. The flow systems evolve by acquiring flow configuration in a definite direction in time if it is free to morph: existing configurations are replaced by easier flowing configurations. One example accounts for this evolution given in this article comes from natural inanimate flow systems: tree-shaped flows. The applications of constructal design method in the fields of heat transfer and fluid flow in engineered systems are also reviewed. The application of multiobjective configurations in the venturi cooling device is studied. In sum, this paper presents an overview of recent developments of constructal design of configuration in engineering. Some discussions and future prospects on this novel research field are provided in this paper to show the emerging development of constructal theory in engineering and other branch fields.


Author(s):  
Nkonko M. Kamwangamalu

This chapter examines the relationship between African languages and the economy by addressing vernacularization against the language ideologies from the perspective of theoretical approaches to the spread of English on the one hand, and recent developments in the economics of language on the other. First, it summarizes postcolonial language-in-education policies in Africa, and the role of English and other former colonial languages in those policies. Next, the chapter discusses theoretical approaches to the spread of English in Africa to provide the background against which the ideologies that inform the spread of English can be understood better. It argues that, for vernacularization to succeed in Africa, especially in the era of globalization, African languages must be assigned an economic value at least in the local linguistic market place.


2021 ◽  
Vol 13 ◽  
Author(s):  
Dunja Petrovic ◽  
Emilia Kouroussis ◽  
Thibaut Vignane ◽  
Milos R. Filipovic

Hydrogen sulfide (H2S), originally considered a toxic gas, is now a recognized gasotransmitter. Numerous studies have revealed the role of H2S as a redox signaling molecule that controls important physiological/pathophysiological functions. The underlying mechanism postulated to serve as an explanation of these effects is protein persulfidation (P-SSH, also known as S-sulfhydration), an oxidative posttranslational modification of cysteine thiols. Protein persulfidation has remained understudied due to its instability and chemical reactivity similar to other cysteine modifications, making it very difficult to selectively label. Recent developments of persulfide labeling techniques have started unraveling the role of this modification in (patho)physiology. PSSH levels are important for the cellular defense against oxidative injury, albeit they decrease with aging, leaving proteins vulnerable to oxidative damage. Aging is one of the main risk factors for many neurodegenerative diseases. Persulfidation has been shown to be dysregulated in Parkinson's, Alzheimer's, Huntington's disease, and Spinocerebellar ataxia 3. This article reviews the latest discoveries that link protein persulfidation, aging and neurodegeneration, and provides future directions for this research field that could result in development of targeted drug design.


2020 ◽  
Vol 48 (3) ◽  
pp. 1019-1034 ◽  
Author(s):  
Rachel M. Woodhouse ◽  
Alyson Ashe

Gene regulatory information can be inherited between generations in a phenomenon termed transgenerational epigenetic inheritance (TEI). While examples of TEI in many animals accumulate, the nematode Caenorhabditis elegans has proven particularly useful in investigating the underlying molecular mechanisms of this phenomenon. In C. elegans and other animals, the modification of histone proteins has emerged as a potential carrier and effector of transgenerational epigenetic information. In this review, we explore the contribution of histone modifications to TEI in C. elegans. We describe the role of repressive histone marks, histone methyltransferases, and associated chromatin factors in heritable gene silencing, and discuss recent developments and unanswered questions in how these factors integrate with other known TEI mechanisms. We also review the transgenerational effects of the manipulation of histone modifications on germline health and longevity.


1988 ◽  
Vol 27 (1) ◽  
pp. 81-83
Author(s):  
Nadeem A. Burney

Its been long recognized that various economies of the world are interlinked through international trade. The experience of the past several years, however, has demonstrated that this economic interdependence is far greater than was previously realized. In this context, the importance of international economic theory as an area distinct from general economics hardly needs any mentioning. What gives international economic theory this distinction is international markets for some goods and effects of national sovereignty on the character of economic activity. Wilfred Ethier's book, which incorporates recent developments in the field, is an excellent addition to textbooks on international economics for one- or twosemester undergraduate courses. The book mostly covers standard topics. A distinguishing feature of this book is its detailed analysis of the flexible exchange rates and a discussion of the various approaches used for their determination. Within each chapter, the author has extensively used facts, figures and major events to clarify the concepts in the light of the theoretical framework. The book also discusses, in a fair amount of detail, the existing international monetary system and the role of various international organizations.


Globus ◽  
2020 ◽  
Author(s):  
Marina Sharifovna Kiyan ◽  
Viktoriya Valerevna Klimentenko

This article discusses a comprehensive theoretical and legal study of the place of case law in the system of sources of law of the Russian Federation. The major focus is devoted to the analysis of various theoretical approaches and court acts that allow to determine the role of case law in the Russian legal system. The conclusion is made that it is necessary to define legally the role of case law and determine its place in the Russian legal system


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