The International Financial Crisis: an Expert Survey

The advent of the international financial crisis, and of its effects on the economy, all the world now face the question how to manage the crisis and what measures to implement to restore a normal condition. In this paper we present and discuss the results and implications of an international expert survey. Our target is to understand the perception with regards to several aspects of the international financial crisis and some possible future implications for policy makers’ authorities.international financial crisis; subprime; expert survey

Is Decoupling in action?

Emerging market economies (also known as emerging economies, EEs) have become important on the world economic stage, where they now play a vital role in international trade and financial flows and account for a conspicuous fraction of the global economic dynamic. Despite the relatively tepid economic growth of advanced economies (AEs) from 2004 to 2007, the growth of EEs continued to be strong during that same period. This behaviour provided some evidence for the so-called ?decoupling hypothesis? that EEs have, over time, become less dependent on AEs. With the recent global financial crisis, the direction of the debate on the ?decoupling? has been partially changed; thus, the discussion remains unresolved. The decoupling hypothesis implies two main consequences. First, the comovement of economic cycles between AEs and EEs should decrease over time. Second, the resilience of the EEs to adverse scenarios in AEs should increase through time. This work sought to identify empirical evidences of the two consequences of decoupling. Two approaches were employed: 1) the Euclidean distance was used to evaluate the correlation of the international economic cycles, and 2) a time-varying Panel VAR model was used to decompose fluctuations in GDP into global, regional, group and country specific components and quantify the time path of the resilience of EEs. Although the Euclidean distance does not provide a clear indication in favour of decoupling, if we consider a sufficiently lengthy time period what does emerge, albeit subject to certain geographical differences, is that the connection between EEs and EAs has changed in that EEs are more resilient to the adverse scenarios that may arise in AEs. This result lends support to the decoupling hypothesis, although it is also clear that the process of strengthening of the EEs, that is, the decoupling process, has not emerged in a gradual, progressive manner, but has, on the contrary, followed a more complex dynamic characterised by ?alternate phases?. This discontinuity over time, together with the geographical peculiarities of the phenomenon, is still to be fully understood

Longterm Influence of Inertia on the Diffusion of a Brownian Particle

We demonstrate experimentally that a Brownian particle is subject to inertial effects at long time scales. By using a blinking optical tweezers, we extend the range of previous experiments by several orders of magnitude up to a few seconds. The measured mean square displacement of a freely diffusing Brownian particle in a liquid shows a deviation from the Einstein-Smoluchowsky theory that diverges with time. These results are consistent with a generalized theory that takes into account not only the particle inertia but also the inertia of the fluid surrounding the particle. This can lead to a bias in the estimation of the diffusion coefficient from finite-time measurements. We show that the decay of the relative error is polynomial and not exponential and, therefore, can have significant effects at time scales relevant for experiments.Comment: 5 pages, 4 figure

Simultaneous measurements of electrophoretic and dielectrophoretic forces using optical tweezers

Herein, charged microbeads handled with optical tweezers are used as a sensitive probe for simultaneous measurements of electrophoretic and dielectrophoretic forces. We first determine the electric charge carried by a single bead by keeping it in a predictable uniform electric field produced by two parallel planar electrodes, then, we examine same bead's response in proximity to a tip electrode. In this case, besides electric forces, the bead simultaneously experiences non-negligible dielectrophoretic forces produced by the strong electric field gradient. The stochastic and deterministic motions of the trapped bead are theoretically and experimentally analysed in terms of the autocorrelation function. By fitting the experimental data, we are able to extract simultaneously the spatial distribution of electrophoretic and dielectrophoretic forces around the tip. Our approach can be used for determining actual, total force components in the presence of high-curvature electrodes or metal scanning probe tips.Comment: 9 pages, 3 figure

Cage Size and Jump Precursors in Glass-Forming Liquids: Experiment and Simulations

Glassy dynamics is intermittent, as particles suddenly jump out of the cage formed by their neighbours, and heterogeneous, as these jumps are not uniformly distributed across the system. Relating these features of the dynamics to the diverse local environments explored by the particles is essential to rationalize the relaxation process. Here we investigate this issue characterizing the local environment of a particle with the amplitude of its short time vibrational motion, as determined by segmenting in cages and jumps the particle trajectories. Both simulations of supercooled liquids and experiments on colloidal suspensions show that particles in large cages are likely to jump after a small time-lag, and that, on average, the cage enlarges shortly before the particle jumps. At large time-lags, the cage has essentially a constant value, which is smaller for longer-lasting cages. Finally, we clarify how this coupling between cage size and duration controls the average behaviour and opens the way to a better understanding of the relaxation process in glass--forming liquids.Comment: Letter, 4 figure

Surface charge and hydrodynamic coefficient measurements of {\it Bacillus subtilis} spore by Optical Tweezers

In this work we report on the simultaneous measurement of the hydrodynamic coefficient and the electric charge of single {\it Bacillus subtilis} spores. The latter has great importance in protein binding to spores and in the adhesion of spores onto surfaces. The charge and the hydrodynamic coefficient were measured by an accurate procedure based on the analysis of the motion of single spores confined by an optical trap. The technique has been validated using charged spherical polystyrene beads. The excellent agreement of our results with the expected values demonstrates the quality of our procedure. We measured the charge of spores of {\it B. subtilis} purified from a wild type strain and from two isogenic mutants characterized by an altered spore surface. Our technique is able to discriminate the three spore types used, by their charge and by their hydrodynamic coefficient which is related to the hydrophobic properties of the spore surface.Comment: 21 pages 5 figure

ESSAY ON ECONOMIC CYCLES IN EMERGING AND ADVANCED COUNTRIES:SYNCHRONIZATION, INTERNATIONAL SPILLOVERS AND THE DECOUPLING HYPOTHESIS

Questo lavoro contribuisce al dibattito sul “decoupling delle Economie emergenti (EE) rispetto alle Economie Avanzate (EA)” rispondendo principalmente alle seguenti domande: “La vulnerabilità delle EE a schock esterni (siano essi reali o del credito) provenienti dalle EA è cambiata nel tempo? E’ cresciuta o si è ridotta, come implica l’ipotesi del decoupling?” Al fine di misurare l’impatto che un eventuale schock esterno avrebbe esercitato sulle EE in diversi periodi degli ultimi decenni, sono stati eseguiti esperimenti di analisi controfattuale utilizzando un modello econometrico Time Varying Panel VAR con coefficienti fattorizzati. Le analisi mostrano che negli ultimi trenta anni le EE sono diventate meno vulnerabili a shock provenienti dalle EA, siano essi di natura reale o shock del credito. Sebbene questo risultato supporti l’idea del decoupling, è importante notare che la resilienza delle EE a shock esterni è evoluta nel tempo in maniera non progressiva ma piuttosto evidenziando fasi di più forte resilienza seguite da fasi di minore resilienza e vice versa; un “sentiero a onde” non ancora pienamente considerato nella letteratura economica. Le EE sono inoltre risultate più vulnerabili a shock del credito rispetto a shock reali; questa maggiore vulnerabilità relativa ha raggiunto il suo picco negli anni più recenti.This work aims to contribute towards the debate on “decoupling of Emerging Economies (EEs) from the Advanced Economies (AEs)” by addressing the following main questions: “Has the EEs’ vulnerability to external shocks (both real and credit shocks) coming from AEs changed over time? If so, has it grown or decreased, as the decoupling hypothesis claims?” In order to measure the impact that external shocks would have on the EEs’ GDP growth in different periods of last decades, counterfactual experiments were performed using an econometric Time Varying Panel VAR model with factorized coefficients. The analyses show that over the last thirty years EEs have become less vulnerable to shocks spreading from the AEs. Despite this represents evidence in favour of the decoupling hypothesis, it is important to note that EEs’ resilience to external shocks has changed in a non-progressive manner over time, with phases of greater resilience followed by others of lower resilience, and vice versa; this outlines a “wave-like” path whose evidence has yet been fully analyzed in the economic literature. Moreover, the EEs have shown to be more vulnerable to credit shocks than to real ones; this greater relative vulnerability has reached its peak in the most recent years

Vascular injury during laparoscopic cholecystectomy: An often-overlooked complication

: Laparoscopic cholecystectomy is one of the most frequently performed procedures in gastrointestinal surgery worldwide. Bleeding complications due to vascular injuries represent an important cause of morbidity and mortality, especially when facing major bleeding during laparoscopy, where bleeding control can be technically challenging in inexperienced hands. Interestingly, the reported incidence rate of conversion to open surgery due to vascular lesions is approximately 0%-1.9%, with a mortality rate of approximately 0.02%. The primary aim of this article was to perform an up-to-date overview regarding the incidence and surgical management of vascular injuries during laparoscopic cholecystectomy according to the available scientific evidence

A Step-by-step Guide to the Realisation of Advanced Optical Tweezers

Since the pioneering work of Arthur Ashkin, optical tweezers have become an indispensable tool for contactless manipulation of micro- and nanoparticles. Nowadays optical tweezers are employed in a myriad of applications demonstrating the importance of these tools. While the basic principle of optical tweezers is the use of a strongly focused laser beam to trap and manipulate particles, ever more complex experimental set-ups are required in order to perform novel and challenging experiments. With this article, we provide a detailed step- by-step guide for the construction of advanced optical manipulation systems. First, we explain how to build a single-beam optical tweezers on a home-made microscope and how to calibrate it. Improving on this design, we realize a holographic optical tweezers, which can manipulate independently multiple particles and generate more sophisticated wavefronts such as Laguerre-Gaussian beams. Finally, we explain how to implement a speckle optical tweezers, which permit one to employ random speckle light fields for deterministic optical manipulation.Comment: 29 pages, 7 figure