This article discusses an algorithmic approach and a computer program based on it to solve an elementary combinatorial problem. Its intended audience is high school students (and laypeople) with an aptitude for abstract thinking and an interest in problem-solving. The algorithm presented here is correct but inefficient. However, it sheds light on a well-known problem in theoretical computer science.
G Rajasekaran was active in research for more than six decades. He made significant contributions in a wide range of areas—hypernuclear physics, flavor physics, current algebra, neutral current weak interactions, integer quark model, string theory, new forms of quantum statistics, neutrino physics, dark matter, etc. He published more than 200 research papers. He was always keen to enlarge his sphere of activity and influence over the development of high-energy physics (HEP) in the country. In the following, we try to summarize some highlights of his vast contributions to research, as well as other academic pursuits, chronologically following his spatial trajectory. While some research is explained in detail, others that require technical knowledge are briefly mentioned here for completeness.
Mosquitoes transmit deadly diseases such as malaria, dengue, Chikungunya, and Zika, leading to a significant number of deaths each year. They are often referred to as ‘the most dangerous animal on Earth’. Despite this, the stealthy methods employed by mosquitoes for sucking blood and the sensory mechanisms involved in the process were discovered only in the last decade. This article explores how mosquitoes locate their human hosts and how their mouthparts work together to draw blood in a strategically covert manner. It discusses the organization of their olfactory organs, including the antennae, mouthparts, and proboscis, as well as the olfactory nerve tracts and the smell centers in the mosquito brain. Additionally, the article highlights various innovations and applications inspired by the adaptive features of mosquitoes.
There are two sets of clues – cryptic clues, and quick clues. The answers to both sets of clues are the same. The solutions will be printed in the next issue.
Notwithstanding the well-established status of quantum chromodynamics (QCD) as the theory of strong interactions, the internal composition of hadrons remains an open problem. Prof. G. Rajasekaran’s (respectfully addressed as Rajaji in the Indian scientific community) work [1], one of the earliest attempts to address this, provided a physically transparent criterion for hadron compositeness using the analytic structure of the ‘K-matrix’. He argued that the absence of K-matrix poles is a distinctive signature of dynamically generated states, providing a clean framework to extract hadron compositeness from scattering amplitudes. In this article, we revisit these pioneering ideas by Rajaji [1] and place them in the context of modern developments, including Weinberg’s compositeness relations, CDD ambiguity, effective field theory approaches, and contemporary lattice QCD analyses.
The double pendulum is a classical model of deterministic chaos, showing extreme sensitivity to initial conditions, all the while specified by fully known classical equations. This first part describes a numerical study of the undamped double pendulum—in Lagrangian form—using high-precision numerical integration with small perturbations in initial conditions resulting in rapid divergence in trajectories. The time-series analysis of trajectories and the computation of the maximal Lyapunov exponent via the two-trajectory method quantifies the divergence. Phase-space portraits can illustrate bounded, but aperiodic, motion with the defining characteristics of nonlinear chaotic systems. All simulations are mounted with open-source Python tools (NumPy, SciPy, Matplotlib, and FuncAnimation), allowing for a transparent and pedagogical environment suitable for advanced undergraduates or graduates in the study of classical mechanics and nonlinear dynamics.
This comprehensive three-part review aims to serve as an introductory guide to the fundamental concepts of quantum computing, with a specific emphasis on their practical applications in molecular modeling and quantum chemistry. The first part introduces the theoretical foundations of quantum computing. It includes the basics of quantum bits, quantum gate operations, quantum circuit construction, and measurement. By bridging the gap between quantum computing and molecular modeling, this series endeavors to equip students and researchers with the essential knowledge necessary to navigate and contribute to this rapidly evolving interdisciplinary field.
There are two sets of clues cryptic clues, and quick clues. The answers to both sets of clues are the same. The solutions will be printed in the next issue.
Viscosity appears quite naturally in the Navier–Stokes equation, just as it does in the Langevin equation for Brownian motion. The issue we address here is: Is there a microscopic understanding of the hydrodynamic viscosity from the fluctuating properties of the surrounding bath? An elucidation of this question may lead to a thermodynamic analysis of hydrodynamic micro-engines à la stochastic thermodynamics and possibly also of their quantum counterparts.
This article serves as an expository and introductory work, exploring generalized Fibonacci numbers through the lens of integer compositions and graph theory. It is particularly suited for students interested in discrete mathematics, providing a combination of combinatorial arguments, bijective proofs, and connections to various discrete structures. Key topics include the relationship between Fibonacci numbers and compositions, graphical representations such as bargraphs and Young diagrams, and extensions to tribonacci and tetranacci sequences. Additionally, the article introduces colored compositions and towers of compositions. To engage readers further, a set of problems is included, designed to be approachable for students and to serve as an entry point for those intrigued by the topics discussed. These problems aim to foster a deeper understanding and appreciation of the rich interplay between Fibonacci sequences and combinatorics.
We relate a well-known identity from order statistics to a curious way of bounding the prime-counting function from below, due to Nair.
Viruses are non-cellular entities universally found in all forms of life, from bacteria to humans. Their profound influence has been highlighted by numerous pandemics throughout history, with the COVID-19 pandemic underscoring their significant impact on our lives, health systems, and economies. Beyond causing disease, viral genes are prevalent in our genomes, raising questions about their evolutionary role. A significant portion of the human genome consists of viral DNA, remnants of ancient infections that have become part of our genetic makeup. This incorporation has profoundly impacted our development and biology. Describing viruses as ‘kingmakers in evolution’ underscores their deep influence on evolutionary processes. Throughout Earth’s history, viruses have shaped genetic diversity, adaptation, and the survival of organisms by driving genetic innovation. They facilitate horizontal gene transfer, introducing new genetic material and enabling the emergence of novel traits and adaptations. Viruses have also contributed to key biological developments, such as the mammalian placenta, likely influenced by endogenous retroviruses. Additionally, the evolutionary arms race between viruses and hosts has spurred the development of sophisticated immune systems. This review explores the multifaceted role of viruses in origin and evolution, beyond their role as pathogens. By examining their impact on genetic diversity, adaptation, and the emergence of new traits, we can better understand how viruses have shaped life on Earth and continue to influence our biological destiny.
Maxwell’s electrodynamics is a rich source of physical and mathematical ideas. Here, we show how the displacement current introduced by Maxwell is related to the mathematical discipline of topology.
India, like much of the world, faces increasing threats to its rich plant biodiversity. In this context, herbaria serve as invaluable repositories of plant diversity, preserving specimens that document past and present floristic patterns. Traditionally, herbaria have been fundamental to plant taxonomy, ecological studies, and conservation research. However, advancements in molecular techniques and computational tools have expanded their utility beyond conventional applications. The digitisation of herbarium collections has further revolutionised botanical research, enabling global accessibility, large-scale meta-analyses, and interdisciplinary studies. The rise of artificial intelligence (AI), deep learning (DL), and machine learning (ML) has enhanced species identification, improved taxonomic classification, and reduced human bias. While digital herbaria offer numerous advantages, including enhanced preservation and remote accessibility, they cannot replace physical collections entirely. A hybrid approach integrating traditional specimen-based research with digital advancements is crucial for ensuring the long-term sustainability of herbaria. By embracing AI, remote sensing, and open-access databases, herbaria will remain indispensable tools for biodiversity conservation and botanical discovery amid environmental change.
The Moon, our nearest celestial neighbor, serves as an invaluable archive of the early Solar System—a pristine record book whose pages remain largely unaltered by the geological processes that have erased Earth’s earliest history. It is also the place where the expansion of the human realm of activities can be envisioned in the near future. How do planetary scientists use the Moon to answer fundamental questions about our cosmic origins: How did the Solar System form and evolve? What does the future hold for the expansion of humanity into space? We examine the scientific methods that allow us to read these ancient records, highlight India’s growing contributions to lunar science through the Chandrayaan missions, and look ahead to the Lunar South Pole as the next great frontier in space exploration. Understanding these ancient worlds is not merely an academic exercise, it provides essential context for our place in the cosmos and charts the path for humanity’s future beyond Earth.
Jane Goodall’s name is synonymous with chimpanzee behaviour and conservation, but what is less well known is that she was a self-taught ethologist and conservationist who entered the field guided only by her love for animals. Her scientific achievements and conservation legacy serve to remind us that science flourishes in the presence of love and compassion, not its absence.
