Superconducting fluctuations--Large Diamagnetism of Low TcT_c Nanoparticles

It is shown that nanoparticles made of low $T_c$ superconductors have large diamagnetic response at temperatures several orders of magnitude above $T_c$. Most features of the recently observed Giant diamagnetism of Au nanorods are explained in terms of superconducting fluctuations, except for the huge magnitude of the effect.Comment: 4 pages, to appear in Phys Rev

Straightforward quantum-mechanical derivation of the Crooks fluctuation theorem and the Jarzynski equality

We obtain the Crooks and the Jarzynski non-equilibrium fluctuation relations using a direct quantum-mechanical approach for a finite system that is either isolated or coupled not too strongly to a heat bath. These results were hitherto derived mostly in the classical limit. The two main ingredients in the picture are the time-reversal symmetry and the application of the first law to the case where an agent performs work on the system. No further assumptions regarding stochastic or Markovian behavior are necessary, neither a master equation or a classical phase-space picture are required. The simplicity and the generality of these non-equilibrium relations are demonstrated, giving very simple insights into the Physics.Comment: 7 pages, 2 figures, pedagogical, improved versio

Mesoscopic Physics and the Fundamentals of Quantum Mechanics

We start by reviewing some interesting results in mesoscopic physics illustrating nontrivial insights on Quantum Mechanics. We then review the general principles of dephasing (sometimes called "decoherence") of Quantum-Mechanical interference by coupling to the environment degrees of freedom. A particular recent example of dephasing by a current-carrying (nonequilibrium) system is then discussed in some detail. This system is itself a manifestly Quantum Mechanical one and this is another illustration of detection without the need for "classical observers" etc. We conclude by describing briefly a recent problem having to do with the orbital magnetic response of conduction electrons (another manifestly Quantum Mechanical property): The magnetic response of a normal layer (N) coating a superconducting cylinder (S). Some recent very intriguing experimental results on a giant paramagnetic component of this response are explained using special states in the normal layer. It is hoped that these discussions illustrate not only the vitality and interest of mesoscopic physics\cite{book} but also its extreme relevance to fundamental issues in Quantum Mechanics.Comment: 25 pages 3 eps figure

High Temperature Superconductivity: A Simple Model Exploiting Hydrogen Bonds

Lately, there has been much interest in high temperature superconductors, and more recently hydrogen-based superconductors. This work offers a simple model which explains the behavior of the superconducting gap based on BCS theory, and reproduces most effects seen in experiments, including the isotope effect and T_c enhancement as a function of pressure. We show that this is due to a combination of the factors appearing in the gap equation: the matrix element between the proton states, and the level splitting of the proton.Comment: 13 pages, 5 figure

Raising Awareness about Water Issues: The Role of Water Symbolism and Proverbs

Sustainable water management is one of the global grand challenges of our time. Tackling this challenge through corrective actions would require the participation of the general public, a public with sound awareness of the challenge and commitment. One such awareness raising intervention could be through the use of water symbolism and proverbs, targeted to particular society. Water has the different symbolism and levels of importance to people, depending of their personal characteristics and socio-demographic factors (e.g. gender, age, occupation, residence). Similarly, water proverbs can also demonstrate attitudes towards water among communities, ethnic groups and whole nations. Such meanings and symbolism could help determine attitude and be a powerful tool towards education. In this context, we describe and propose a psychological Health Belief Model (HBM) as a way to explain behaviour and stimulate sustainable water management practice

Optimal public investment, growth, and consumption : evidence from African countries.

How much does public capital matter for economic growth? How large should it be? This paper attempts to answer these questions, taking the case of SSA countries. It develops and estimates a model that posits a nonlinear relationship between public investment and growth, to determine the growth-maximizing public investment GDP share. It empirically also accounts for the crowding-in and crowding-out effects between public and private investment, with equations estimated separately and simultaneously, using System GMM. The paper further runs simulation and examines the public investment GDP share that maximizes consumption. This is estimated to be between 8.4 percent and 11.0 percent. The results from estimating the growth model are in the middle of this range, which is larger than the observed value of 7.2 percent at the end of the sample period. These outcomes suggest that, on average, there has been public under-investment in Africa, contrary to previous finding

Traditional and Innovative ways of Teaching Amharic Alphabet

Amharic is one of the few African languages that has its own indigenous script called Fidal. Teaching and learning the Fidal can be as daunting as it can be boring. In this article traditional and innovative ways of teaching the Fidal is considered