pp 513-513 Editorial
pp 516-516 Science Smiles
pp 517-524 Article-in-a-Box
pp 525-548 General Article
W F R Weldon first clearly formulated the principles of naturalselection in terms of what would have to be observed innatural populations in order to conclude that natural selectionwas, indeed, acting in the manner proposed by Darwin.The approach he took was the statistical method developedby Galton, although he was closer to Darwin’s conception ofselection acting on small individual variations than Galtonwas. Weldon, together with Karl Pearson, who supplied thestatistical innovations needed to infer the action of selectionfrom populational data on trait distributions, laid the foundationsof biometry and provided the first clear evidence of bothstabilizing and directional selection in natural populations.
pp 549-575 General Article
Radio Frequency Identification (RFID) has been around sinceearly 2000. Its use has currently become commonplace as thecost of RFID tags has rapidly decreased. RFID tags have alsobecome more ‘intelligent’ with the incorporation of processorsand sensors in them. They are widely used now in manyinnovative ways. RFIDs are an integral part of Internet ofThings (IOT) and IT systems of smart cities. In this article,we introduce the technology used by RFID systems, illustratetheir use in several applications, and discuss problems of privacyand security when they are used.
pp 577-596 General Article
Even as the theory of relativity is more than a hundred yearsold, it is not within easy reach of undergraduate students.These students have an insatiable urge to learn more aboutit even if the full machinery of the tools required to studythe same is not within their comfortable reach. The recentdetection of gravitational waves has only augmented their enthusiasmabout the General Theory of Relativity (GTR), developedjust over a hundred years now, encapsulated in Einstein’sField Equations. The GTR provided a consistent formulationof the theory of gravity, removed the anomalies inthe Newtonian model, and predicted spectacular natural phenomenawhich eventual experiments have testified to. Thispedagogical article retraces some of the major milestones thatled to the GTR and presents a simple numerical simulation ofthe GTR advance of the perihelion of planetary motion aboutthe sun.
pp 597-610 General Article
A star burns its nuclear fuel and balances gravitation by thepressure of the heated gas, during its active lifetime. Afterthe exhaustion of the nuclear fuel, a low mass star findspeace as a ‘white dwarf’, where the pressure support againstgravitation is provided by Fermi-degenerate electrons. However,for massive stars, the gravitational squeeze becomes sosevere that in the final phase of evolution, the average densityapproximately equals the nuclear density. At such densities,most of the protons combine with electrons to convertthemselves into neutrons. A `neutron star', composed of suchneutron-rich material, is host to some fascinating physics arisingout of its amazingly compact state of matter (where a solarmass is packed inside a sphere of radius ∼ 10Km).
pp 611-618 Classroom
In this series of articles, the authors discuss various phenomenain fluid dynamics, which may be investigated via tabletopexperiments using low-cost or home-made instruments. Thefourth article in this series is about soap films and some interestingexperiments based on them.
pp 619-619 Information and Announcements
pp 620-620 Information and Announcements
pp 621-621 Information and Announcements
pp 623-623 Flowering Trees