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      Volume 25, Issue 4

      April 2020,   pages  453-609

    • Editorial

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    • Science Smiles

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    • George Robert Price (16 October 1922–5 January 1975)

      Amitabh Joshi

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    • A New Bug on the Block

      Shahid Jameel

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      In December 2019, clusters of pneumonia cases started show-ing up in the Hubei region of China, especially in its largestcity Wuhan. As these piled up, researchers at the ChineseAcademy of Sciences’ laboratories and the Chinese Centrefor Disease Control started looking for the cause. This turnedout to be a new virus, whose genetic sequence matched veryclosely with two coronaviruses isolated from bats in China in2018.

    • Lockdown Maths Part 1: Why We Must Comply

      Partha P Majumder

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      The following article is reproduced with permission fromThe Telegraph,Kolkata (Guest Column, Published on 25March2020).

    • Lockdown Maths Part 2 Relaxation of Lockdown—Perilous

      Partha P Majumder

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      The following article is reproduced with permission fromThe Telegraph, Kolkata (Guest Column, Published 30 March2020).

    • The Price Equation and the Mathematics of Selection

      Amitabh Joshi

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      Fifty years ago, a small one and a half page paper withouta single reference was published in the leading journal Na-ture. The paper laid out the most general mathematical for-mulation of natural selection that would work for all kindsof selection processes and under any form of inheritance (notjust biological evolution and Mendelian genes), although thepaper discussed the issue in a genetical framework. Writ-ten by a maverick American expatriate in England, with noprior background of studying evolution or genetics, the paperhad initially been turned down by the editor of Nature as toodifficult to understand. Largely ignored by the evolutionarybiology community till the 1990s, the Price Equation is nowwidely recognized as an extremely useful conceptualization,permitting the incorporation of non-genetic inheritance intoevolutionary models, serving to clarify the relationship be-tween kin-selection and group-selection, unifying varied ap-proaches used in the past to model evolutionary change, andforming the foundation of multi-level selection theory.

    • The Central Force Problem in n Dimensions

      V Balakrishnan Suresh Govindarajan S Lakshmibala

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      The motion of a particle moving under the influence of acentral force is a fundamental paradigm in dynamics. Theproblem of planetary motion, specifically the derivation ofKepler’s laws motivated Newton’s monumental work, PrincipiaMathematica, effectively signalling the start of modernphysics. Today, the central force problem stands as a basiclesson in dynamics. In this article, we discuss the classicalcentral force problem in a general number of spatialdimensions n, as an instructive illustration of important aspectssuch as integrability, super-integrability and dynamicalsymmetry. The investigation is also in line with the realisationthat it is useful to treat the number of dimensions as avariable parameter in physical problems. The dependenceof various quantities on the spatial dimensionality leads to aproper perspective of the problems concerned. We consider,first, the orbital angular momentum (AM) in n dimensions,and discuss in some detail the role it plays in the integrabilityof the central force problem. We then consider an importantsuper-integrable case, the Kepler problem, in n dimensions.The existence of an additional vector constant of the motion(COM) over and above the AM makes this problem maximallysuper-integrable. We discuss the significance of theseCOMs as generators of the dynamical symmetry group of theHamiltonian. This group, the rotation group in n + 1 dimensions,is larger than the kinematical symmetry group for ageneral central force, namely, the rotation group in n dimensions.

    • Fundamental Concepts of Synchronization: An Introduction: From Classical to Modern

      Nitu Kumari Shubhangi Dwivedi

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      Objects with rhythms naturally synchronize. Synchronizationis the coordination of events in order to run the systemuniformly. Yet the phenomenon went entirely undocumenteduntil 1665. Since the pioneering description of synchronizationby Huygens, the phenomenon has been studied by variousresearchers in an interdisciplinary manner. Many researchershave contributed to the development of synchronizationtheory proving that synchronization occurs in couplednon-linear dissipative oscillators. Such oscillators rangefrom mechanical clocks and population dynamics to humanheart and neural networks. This article aims to explain thebasic principles of synchronization theory. The history andapplications of synchronization are discussed in real-worldscenarios. We address different types of synchronization witha detailed discussion on the simplest type of synchronization.The phenomenon of synchronization applies to oscillations ofdifferent forms—periodic, noisy, and chaotic in nature. Here,we specifically discuss the oscillators which can hold synchronization.In particular, we provide an overview of self-sustainedperiodic and chaotic oscillators with a detailed description ofdifferent forms of these oscillators in phase space. Further, asummary of further research challenges has also been givenfor the future development of advanced applications based onnatural synchronization phenomenon.

    • Permissible Synthetic Food Dyes in India

      Jyoti Mittal

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      Since prehistoric times, people have been fascinated with colors.From cave paintings to the latest gadgets, color has beena constant companion of humans. Coloring materials aka

      ‘dyes’ aren’t just for fabrics but have been added to varioustypes of food to enhance their appeal. Evidently, this coloringchemicals have their origin in natural products, which laterexpanded to the huge market of artificial food dyes. Artificialfood colorings have been in the controversy for many yearsand scrutinized for being possibly linked to cancer, allergiesand hyperactivity. Globally, natural as well as artificial dyesare being cautiously researched and regulated by the foodsafety authorities. In India, the Prevention of Food AdulterationAct, 1954 (now called the Food Safety and StandardsAct, 2006), has been implemented for the quality assurance ofvarious types of foods and food products, and only eight dyeshave been suggested edible, but within prescribed limits. Thepresent article explores the history and journey of these captivatingmaterials which have been brightening our world formore than 3500 years, along with a detailed overview of theirphysical and chemical properties, and the usage and toxicityof the eight permissible food dyes in India.

    • A Single Measurement Method to Find Refractive Index

      Amal Nathan Joseph

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      The article discusses a simplemethod to find the angle ofminimumdeviation of a general prism, not necessarily equilateralor isosceles. The method uses a single measurement andrequires a compass, ruler, some pins, and no additional material.It is precise and accurate. We present the method firstand then the justification.

    • The Marvel and the Mystery of Quantum Mechanics – Some Reflections

      N Mukunda

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      The creation of quantum mechanics is one of the most dramatic developments in thephysics of the 20th century. After the period 1900–1924, during which the Law of BlackBody Radiation, wave particle duality for light and formatter, the general quantisation ofenergy and stability of matter and the laws of spectroscopy had begun to be understood,the mathematical structure of quantum mechanics was discovered amazingly rapidly injust under two years, 1925–1927. On the other hand, the physical interpretation andmeaning of this structure required an enormous effort, in which the uncertainty and complementarityprinciples, the Born probability interpretation and rule and the wave functioncollapse idea, all played important roles. While quantum mechanics has all alongbeen amazingly successful in numerous applications, many puzzling questions about interpretationremain and continue to be pursued till today, though the focus has shiftedfrom wave particle duality to entanglement and its signatures and consequences. This article gives an impressionistic account of these developments, accompanied by comments on the origins of human intuition and the meaning of human understanding of nature

      [1].

    • Deciphering the Gene Machine Face-to-Face With Professor Venki Ramakrishnan

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      The creation of quantum mechanics is one of the most dramatic developments in thephysics of the 20th century. After the period 1900–1924, during which the Law of BlackBody Radiation, wave particle duality for light and formatter, the general quantisation ofenergy and stability of matter and the laws of spectroscopy had begun to be understood,the mathematical structure of quantum mechanics was discovered amazingly rapidly injust under two years, 1925–1927. On the other hand, the physical interpretation andmeaning of this structure required an enormous effort, in which the uncertainty and complementarityprinciples, the Born probability interpretation and rule and the wave functioncollapse idea, all played important roles. While quantum mechanics has all alongbeen amazingly successful in numerous applications, many puzzling questions about interpretationremain and continue to be pursued till today, though the focus has shiftedfrom wave particle duality to entanglement and its signatures and consequences. This article gives an impressionistic account of these developments, accompanied by comments on the origins of human intuition and the meaning of human understanding of nature

      [1].

    • Pied Kingfisher (Ceryle rudis)

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