Enrique Canessa

One year of ICTP diploma courses on-line using the automated EyA recording system

The 12-month pre-Ph.D. ICTP Diploma Courses in the fields of Condensed Matter Physics, High Energy Physics, Mathematics, Earth System Physics and Basics Physics have been recorded using the automated, low cost recording system called EyA developed in-house. We discuss the technical details on how these recordings were implemented, together with some web usage statistics and students feedback. As yet, no similar endeavor has been made to put on-line a complete high-level Diploma Programme, due to the high costs involved when using alternative recording solutions. These recordings are freely available on the website www.ictp.tv.

Stock Market and Motion of a Variable Mass Spring

We establish an analogy between the motion of spring whose mass increases linearly with time and volatile stock market dynamics within an economic model based on simple temporal demand and supply functions [E. Canessa, J. Phys. A 33 (2000) 3637]. The total system energy Et is shown to be proportional to a decreasing time dependent spring constant kt. This model allows to derive log-periodicity cos[log(t−tc)] on commodity prices and oscillations (surplus and shortages) in the level of stocks. We also made an attempt to connect these results to the Tsallis statistics parameter q based on a possible force–entropy correlation [E. Canessa, Physica A 341(2004) 165] and find that the Tsallis second entropic term ∑i=1Wpiq/(q−1) relates to the square of the demand (or supply) function.

Theory of analogous force on number sets

A general statistical thermodynamic theory that considers given sequences of x-integers to play the role of particles of known type in an isolated elastic system is proposed. By also considering some explicit discrete probability distributions px for natural numbers, we claim that they lead to a better understanding of probabilistic laws associated with number theory. Sequences of numbers are treated as the size measure of finite sets. By considering px to describe complex phenomena, the theory leads to derive a distinct analogous force fx on number sets proportional to (∂px/∂x)T at an analogous system temperature T. In particular, this leads to an understanding of the uneven distribution of integers of random sets in terms of analogous scale invariance and a screened inverse square force acting on the significant digits. The theory also allows to establish recursion relations to predict sequences of Fibonacci numbers and to give an answer to the interesting theoretical question of the appearance of the Benfords law in Fibonacci numbers. A possible relevance to prime numbers is also analyzed.

Supporting science in developing countries using open technologies

We describe our contributions in using information and communication technologies (ICT) to address the digital and knowledge divides in developing regions. These include the implementation of new prototype systems using state-of-the-art, low-cost technologies based on the scientific audience, the local information technology infrastructure and the level of support available from local technical staff. Efforts are made to provide the necessary capacity and know-how to understand and manage their available information infrastructure with the final goal of supporting their science to allow participation at an international level.

Making ideas at scientific fabrication laboratories

Creativity, together with the making of ideas into fruition, is essential for progress. Today the evolution from an idea to its application can be facilitated by the implementation of Fabrication Laboratories, or FabLabs, having affordable digital tools for prototyping. FabLabs aiming at scientific research and invention are now starting to be established inside Universities, Research Centers and Schools. We review the setting up of the ICTP Scientific FabLab in Trieste, Italy, give concrete examples on the use in physics, and propose to replicate world-wide this class of multi-purpose workplaces within academia as a support for physics and math education and for community development.

Possible connection between probability, spacetime geometry and quantum mechanics

Following our discussion [E. Canessa, Physica A 375 (2007) 123] to associate an analogous probabilistic description with spacetime geometry in the Schwarzschild metric from the macro- to the micro-domain, we argue that there is a possible connection among normalized probabilities P, spacetime geometry (in the form of Schwarzschild radii rs) and quantum mechanics (in the form of complex wave functions ψ), namely Pθ,φ,t(n)≈Rs(n)/rs=|ψn(n)(X(n))|2/|ψn(x)|2. We show how this association along different (n)-nested surfaces—representing curve space due to an inhomogeneous density of matter—preserves the postulates of quantum mechanics at different geometrical scales.

A web community to foster science in developing countries: www.ictp.it

The experiences with the new ICTP website, aiming to satisfy the need for a modern and appealing image, as well as provide tailored online information and services to its scientists (in-house and around the world), are discussed as a case-study of an emerging web-based international community. This approach, which to our knowledge has not been similarly employed by the scientific community in the past, keeps in mind the special audience and the uniqueness of the ICTP scientific structure and organisation. The present approach is a decentralised architecture that offers space and freedom for creativity specific to various scientific programmes, while managing a minimal amount of common structure. The new website was developed using open source technologies and web standards certified by W3C.

Possible force–entropy correlation

A statistical thermodynamic approach of moving particles forming an elastic body is presented which leads to reveal molecular–mechanical properties of classical and nonextensive dynamical systems. We derive the Boltzmann–Gibbs (BG) entropy form and relate it to Newtons law of motion in relation to a distinct tensile force acting on the systems at constant volume and number of particles. Tsallis generalization of the BG entropy is deduced assuming the thermal energy of the particles to be proportional to their energy states by the nonextensivity factor q−1.

FINITE-SIZE SCALING IN TWO-DIMENSIONAL CONTINUUM PERCOLATION MODELS

We test the universal finite-size scaling of the cluster mass order parameter in two-dimensional (2D) isotropic and directed continuum percolation models below the percolation threshold by computer simulations. We found that the simulation data in the 2D continuum models obey the same scaling expression of mass M to sample size L as generally accepted for isotropic lattice problems, but with a positive sign of the slope in the ln–ln plot of M versus L. Another interesting aspect of the finite-size 2D models is also suggested by plotting the normalized mass in 2D continuum and lattice bond percolation models versus an effective percolation parameter, independent of the system structure (i.e., lattice or continuum) and of the possible directions allowed for percolation (i.e., isotropic or directed) in regions close to the percolation thresholds. Our study is the first attempt to map the scaling behavior of the mass for both lattice and continuum model systems into one curve.

Sterically stabilized colloidal dispersions: beyond hard spheres

Sterically stabilized colloidal dispersions, such as PMMA, have long been regarded as archetypal realizations of hard spheres and hard-sphere mixtures. Indeed, this is precisely what is found in studies of these systems as a function of the volume fraction, at constant temperature. However, a much richer behaviour - which goes beyond what is expected from just hard spheres - is found as a function of both volume fraction and temperature T. For instance, sterically stabilized colloids are known to exhibit both upper (high-T) and lower (low-T) two-phase behaviour, such that the former is temperature sensitive but the latter is not. We review model calculations based on a double Yukawa potential that exhibits some of the rich phase behaviour found experimentally, and predicting other behaviour which has not yet been found by experiment. Both the former and latter show a degree of similarity to the phase behaviour of polymer solutions. We also present preliminary results for the phase behaviour of bidisperse model sterically stabilized colloids.