Snippets of physics

How does one study quantum mechanics in an accelerated frame? The answer to this question leads to some surprising insights into the solutions of the Schräodinger equation for harmonic oscillator!     

Snippets of physics

The statistical mechanics of a system of particles interacting through gravity leads to several counter-intuitive features. We explore one of them, called Antonov instability, in this installment.     

Reagent integration and controlled release for multiplexed nucleic acid testing in disposable thermoplastic 2D microwell arrays

The seamless integration of reagents into microfluidic devices can serve to significantly reduce assay complexity and cost for disposable diagnostics. In this work, the integration of multiplexed reagents into thermoplastic 2D microwell arrays is demonstrated using a scalable pin spotting technique. Using a simple and low-cost narrow-bore capillary spotting pin, high resolution deposition of concentrated reagents within the arrays of enclosed nanoliter-scale wells is achieved. The pin spotting method is further employed to encapsulate the deposited reagents with a chemically modified wax layer that serves to prevent disruption of the dried assay components during sample introduction through a shared microchannel, while also enabling temperature-controlled release after sample filling is complete. This approach supports the arbitrary patterning and release of different reagents within individual wells without crosstalk for multiplexed analyses. The performance of the in-well spotting technique is characterized using on-chip rolling circle amplification to evaluate its potential for nucleic acid-based diagnostics.     

Snippets of physics

The major contribution of Kepler was in discovering his laws of planetary motion, one of which states that planets move in elliptical orbits around the Sun which is located at one of the foci of the ellipse. The motion of a test particle in an inverse square force law is usually called the Kepler problem. We will examine several aspects of this motion in this last installment of Snippets in Physics.     

Snippets of physics

The probability amplitude for a particle to propagate from event to event in spacetime shows some nice similarities with the corresponding propagator for the electromagnetic wave amplitude discussed in the last installment. In fact, this analogy provides an interesting insight into the transition from quantum field theory to quantum mechanics! T Padmanabhan works at IUCAA, Pune and is interested in all areas of theoretical physics, especially those which have something to do with gravity.     

Prevalence of insulin resistance in first degree relatives of type-2 diabetes mellitus patients: A prospective study in north Indian population

A total of 172 first degree relatives (FDRs) and 178 controls were included in this study. All the cases and controls were subjected to various anthropometric measurements, fasting and postprandial glucose estimation, fasting insulin measurement and fasting lipid profile. Results revealed the prevalence of Impaired Fasting Glucose (IFG) (cases 37% Vs controls 11.6%), Impaired Glucose Tolerance (IGT) (cases 34.3% Vs controls 11.2%) and diabetes (cases 11.05% controls 3.37%) was significantly higher in first degree relatives. Insulin resistance was measured using various methods, which included fasting plasma insulin (FPI), Homeostasis Model Assessment for Insulin Resistance (HOMA_IR), insulin sensitivity index (ISI) (Mffm/l). Prevalence of insulin resistance (Insulin Resistance) as observed comparing FPI and HOMA_IR in cases and controls was 43.6% and 11.24% (P=0.005) and 37.8% and 12.47% (P=0.000) respectively. Prevalence of IR (Insulin Resistance) observed in cases having Normal Glucose Tolerance (NGT), Impaired Fasting Glucose (IFG), Impaired Glucose Tolerance (IGT) and diabetes mellitus measuring FPI Vs HOMA_IR was 37.5% vs 30.2%, 45% vs 40%, 38.98% vs 37.28% and 36.84% vs 31.57% as accordingly. However, ISI (Mffm/l) was not found to be a promising index for IR due to its poor specificity. Though HOMA is taken as gold standard for measurement of IR globally, our study observed fasting plasma insulin representing high sensitivity (89.7%) and specificity (93.3%) as compared to HOMA. Thus FPI had emerged in this work as a simple and reliable test for diagnosing insulin resistance across the population susceptible to develop diabetes including FDRs.     

Snippets of physics

The Coulomb problem, which corresponds to motion in a potential that varies as r ⁻¹, has a peculiar symmetry which leads to a phenomenon known as ‘accidental’ degeneracy. This curious feature exists both in the classical and quantum domain and is best understood by studying a more general potential and obtaining the Coulomb problem as a limiting case.     

Snippets of physics

Few processes in nature are as ubiquitous as the random walk which combines extraordinary simplicity of concept with considerable complexity in the final output. In this and the next installment, we shall examine several features of this remarkable phenomenon.