scholarly journals Viruses and fullerenes – symmetry as a common thread?

2014 ◽  
Vol 70 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Pierre-Philippe Dechant ◽  
Jess Wardman ◽  
Tom Keef ◽  
Reidun Twarock
Keyword(s):  
Mathematical Models ◽  
Virus Structure ◽  
Carbon Chemistry ◽  
Icosahedral Group ◽  
Symmetry Approach ◽  
Common Thread ◽  
Carbon Onions ◽  
Organizational Principle ◽  
Affine Symmetry

The principle of affine symmetry is applied here to the nested fullerene cages (carbon onions) that arise in the context of carbon chemistry. Previous work on affine extensions of the icosahedral group has revealed a new organizational principle in virus structure and assembly. This group-theoretic framework is adapted here to the physical requirements dictated by carbon chemistry, and it is shown that mathematical models for carbon onions can be derived within this affine symmetry approach. This suggests the applicability of affine symmetry in a wider context in nature, as well as offering a novel perspective on the geometric principles underpinning carbon chemistry.

scholarly journals Models of viral capsid symmetry as a driver of discovery in virology and nanotechnology

2021 ◽  
Vol 43 (1) ◽  
pp. 20-24
Author(s):  
Pierre-Philippe Dechant ◽  
Reidun Twarock
Keyword(s):  
Symmetry Breaking ◽  
Mathematical Modelling ◽  
Mathematical Models ◽  
Antiviral Therapy ◽  
Viral Protein ◽  
Viral Capsid ◽  
Virus Structure ◽  
The Way

Viruses are prominent examples of symmetry in biology. A better understanding of symmetry and symmetry breaking in virus structure via mathematical modelling opens up novel perspectives on how viruses form, evolve and infect their hosts. In particular, mathematical models of viral symmetry pave the way to novel forms of antiviral therapy and the exploitation of viral protein containers in bio-nanotechnology.

Introduction to the Forum on Cluttering: Rays of Hope Shine Around the World

2019 ◽  
Vol 4 (6) ◽  
pp. 1566-1567
Author(s):  
Isabella Reichel
Keyword(s):  
Professional Preparation ◽  
Joint Effort ◽  
Feedback Training ◽  
Successful Communication ◽  
Self Help ◽  
The World ◽  
Common Thread ◽  
Evidence Based Treatments ◽  
Attention Performance ◽  
Self Help Groups

Purpose In the 10 years since the International Cluttering Association (ICA) was created, this organization has been growing in the scope of its initiatives, and in the variety of resources it makes available for people with cluttering (PWC). However, the awareness of this disorder and of the methods for its intervention remain limited in countries around the world. A celebration of the multinational and multicultural engagements of the ICA's Committee of the International Representatives is a common thread running through all the articles in this forum. The first article is a joint effort among international representatives from five continents and 15 countries, exploring various themes related to cluttering, such as awareness, research, professional preparation, intervention, and self-help groups. The second article, by Elizabeth Gosselin and David Ward, investigates attention performance in PWC. In the third article, Yvonne van Zaalen and Isabella Reichel explain how audiovisual feedback training can improve the monitoring skills of PWC, with both quantitative and qualitative benefits in cognitive, emotional, and social domains of communication. In the final article, Hilda Sønsterud examines whether the working alliance between the client and clinician may predict a successful cluttering therapy outcome. Conclusions Authors of this forum exchanged their expertise, creativity, and passion with the goal of solving the mystery of the disconcerting cluttering disorder with the hope that all PWC around the globe will have access to the most effective evidence-based treatments leading to blissful and successful communication.

Handbook of Mathematical Models for Languages and Computation

2019 ◽  
Author(s):  
Alexander Meduna ◽  
Petr Horacek ◽  
Martin Tomko
Keyword(s):  
Mathematical Models

Dependence of Current Harmonics of Greenhouse Irradiators on Supply Voltage

2020 ◽  
pp. 85-88 ◽  
Author(s):  
Nadezhda P. Kondratieva
Keyword(s):  
Mathematical Models ◽  
Supply Voltage ◽  
Harmonic Distortion ◽  
Feasibility Studies ◽  
Power Losses ◽  
Voltage Level ◽  
Supply Networks ◽  
Current Harmonics ◽  
Cable Lines ◽  
Harmonic Composition

The article describes the results of the study concerning the effect of the voltage level on current harmonic composition in greenhouses irradiators. It is found that its change affects the level of current harmonics of all types of the studied greenhouse irradiators. With decrease of nominal supply voltage by 10 %, the total harmonic distortion THDi decreases by 9 % for emitters equipped with high pressure sodium lamps (HPSL), by 10 % for emitters with electrode-less lamps and by 3 % for LED based emitters. With increase of nominal supply voltage by 10 %, THDi increases by 23 % for lighting devices equipped with HPSL, by 10 % for irradiators with electrode-less lamps and by 3 % for LED based emitters. Therefore, changes of supply voltage cause the least effect on the level of current harmonics of LED based emitters and then the emitters with electrode-less lamps. Change of the level of supply voltage causes the greatest effect on the level of current harmonics of HPSL based irradiators. Mathematical models of dependence of THDi on the level of supply voltage for greenhouse emitters equipped with LED, electrode-less lamps and HPSL lamps were formulated. These mathematical models may be used for calculations of total current when selecting transformers and supply cable lines for greenhouse lighting devices, for design of new or reconstruction of existing irradiation systems of greenhouse facilities, and for calculation of power losses in power supply networks of greenhouse facilities during feasibility studies for energy saving and energy efficiency increasing projects.

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