Mechanisms of Self-Organization and Finite Size Effects in a Minimal Agent Based Model

We present a detailed analysis of the self-organization phenomenon in which the stylized facts originate from finite size effects with respect to the number of agents considered and disappear in the limit of an infinite population. By introducing the possibility that agents can enter or leave the market depending on the behavior of the price, it is possible to show that the system self-organizes in a regime with a finite number of agents which corresponds to the stylized facts. The mechanism to enter or leave the market is based on the idea that a too stable market is unappealing for traders while the presence of price movements attracts agents to enter and speculate on the market. We show that this mechanism is also compatible with the idea that agents are scared by a noisy and risky market at shorter time scales. We also show that the mechanism for self-organization is robust with respect to variations of the exit/entry rules and that the attempt to trigger the system to self-organize in a region without stylized facts leads to an unrealistic dynamics. We study the self-organization in a specific agent based model but we believe that the basic ideas should be of general validity.Comment: 14 pages, 7 figure

Nonclassical Light in Interferometric Measurements

It is shown that the even and odd coherent light and other nonclassical states of light like superposition of coherent states with different phases may replace the squeezed light in interferometric gravitational wave detector to increase its sensitivity. (Contribution to the Second Workshop on Harmonic Oscillator, Cocoyoc, Mexico, March 1994)Comment: 8 pages,LATEX,preprint of Naples University, INFN-NA-IV-94/30,DSF-T-94/3

Stacked optical antennas for plasmon propagation in a 5 nm-confined cavity

The sub-wavelength concentration and propagation of electromagnetic energy are two complementary aspects of plasmonics that are not necessarily co-present in a single nanosystem. Here we exploit the strong nanofocusing properties of stacked optical antennas in order to highly concentrate the electromagnetic energy into a 5 nm metal-insulator-metal (MIM) cavity and convert free radiation into guided modes. The proposed nano-architecture combines the concentration properties of optical nanoantennas with the propagation capability of MIM systems, paving the way to highly miniaturized on-chip plasmonic waveguiding

Knowledge representation for culturally competent personal robots: requirements, design principles, implementation, and assessment

Culture, intended as the set of beliefs, values, ideas, language, norms and customs which compose a person’s life, is an essential element to know by any robot for personal assistance. Culture, intended as that person’s background, can be an invaluable source of information to drive and speed up the process of discovering and adapting to the person’s habits, preferences and needs. This article discusses the requirements posed by cultural competence on the knowledge management system of a robot. We propose a framework for cultural knowledge representation that relies on (i) a three layer ontology for storing concepts of relevance, culture specific information and statistics, person-specific information and preferences; (ii) an algorithm for the acquisition of person-specific knowledge, which uses culture specific knowledge to drive the search; (iii) a Bayesian Network for speeding up the adaptation to the person by propagating the effects of acquiring one specific information onto interconnected concepts. We have conducted a preliminary evaluation of the framework involving 159 Italian and German volunteers and considering 122 among habits, attitudes and social norms

Using microbiological sampling to evaluate the efficacy of nasofibroscope disinfection: The tristel trio wipes system in ear–nose–throat (ENT) endoscopy

Disinfection and sterilization are needed for guaranteeing that medical and surgical instruments do not spread contagious microorganisms to patients. The aim of this study was to evaluate the efficacy of a simple manual technique of high-level disinfection (HLD) of flexible fiberoptic nasofibroscopes (FFNs) with wipes impregnated with a chlorine dioxide solution (Tristel Trio Wipes System—TTW) against a conventional automated washer machine (Soluscope ENT, Cimrex 12—AW). FFNs used in 62 patients undergoing endoscopy at an ENT clinic were sampled according to an aseptic procedure. For each nasoendoscopy, microbiological samples were taken at two times: (1) after a patient’s nasoendoscopy and (2) immediately after high-level disinfection. Ten microliters of each prepared sample were inoculated onto specific culture media for the detection of nasopharyngeal flora microorganisms. The microbiological results obtained from 62 post-disinfection samples revealed bacterial growth on two FFNs disinfected with AW, and five FFNs disinfected with TTW, but this difference is not statistically significant. None of the isolates were pathogenic bacteria. Our results are different than the results obtained by two previously published studies on the TTW system. In both studies, sampling was carried out by swabbing the tip and the handle surface of FFNs. This sampling method was the least effective method means of detecting bacteria on a surface. It can be concluded that the two disinfection systems allow providers to obtain a reduction of the saprophytic and pathogenic microbial load

Multi-scheme approach for efficient surface plasmon polariton generation in metallic conical tips on AFM-based cantilevers

We report on the possibility of realizing adiabatic surface plasmon polaritons compression on metallic conical tips built-in on AFM cantilevers by means of different approaches. The problem is faced considering the role of the source, when linear and radial polarizations are assumed, associated to different fabrication schemes. Nano-patterned devices properly combined with metallic conical tips can affect the adiabatic characteristic of the surface electric field. The results are analyzed in terms of tradeoff between fabrication difficulties and device performances. Suggestions on the best possible scheme are provided

Emergent Chiral Symmetry: Parity and Time Reversal Doubles

There are numerous examples of approximately degenerate states of opposite parity in molecular physics. Theory indicates that these doubles can occur in molecules that are reflection-asymmetric. Such parity doubles occur in nuclear physics as well, among nuclei with odd A $\sim$ 219-229. We have also suggested elsewhere that such doubles occur in particle physics for baryons made up of `cbu' and `cbd' quarks. In this article, we discuss the theoretical foundations of these doubles in detail, demonstrating their emergence as a surprisingly subtle consequence of the Born-Oppenheimer approximation, and emphasizing their bundle-theoretic and topological underpinnings. Starting with certain ``low energy'' effective theories in which classical symmetries like parity and time reversal are anomalously broken on quantization, we show how these symmetries can be restored by judicious inclusion of ``high-energy'' degrees of freedom. This mechanism of restoring the symmetry naturally leads to the aforementioned doublet structure. A novel by-product of this mechanism is the emergence of an approximate symmetry (corresponding to the approximate degeneracy of the doubles) at low energies which is not evident in the full Hamiltonian. We also discuss the implications of this mechanism for Skyrmion physics, monopoles, anomalies and quantum gravity.Comment: 32 pages, latex. minor changes in presentation and reference

Non-invasive tool to assess heart rhythm in Zebrafish embryos

In the last years the zebrafish (Danio rerio) has emerged as model organism for cardiac research, in spite of the morphological differences with the human heart. In consequence of the similarity to humans in the early function, the zebrafish embryo has been suggested as an ideal model i) to study the molecular mechanism of cardiac development, and ii) to identify genes related to congenital cardiac defects in human [1]. The overall similarity of zebrafish embryos and human, in responses to human cardiotoxic drugs, was demonstrated, for example, in drug-induced cardiac arrhythmia [2]. For this reason, several methods have been developed to assess cardiac functions in zebrafish embryos [3,4]. Unfortunately, all these techniques suffer from drawbacks (time consuming, skillful operator are ended to perform the experiments) which limit their applications for large scale studies. The development in digital imaging has recently made analysis of cardiac functions in genetically modified transparent zebrafish embryos easier. This allowed to assess non-invasively heart rate variability in zebrafish embryos from videos of beating heart, but without measuring heartbeat rhythm, an important indicator of the cardiac function (heartbeat regularity is associated with cardiotoxicity in humans [1]), from power spectrum of heart signal. In the present study, we present a simple, non-invasive method that, by video-recording embryo images using confocal microscopy, and integrating image processing and power spectral analysis, allows to measure the heartbeat rhythm in zebrafish embryos heart chambers (atrium, ventricle, bulb) (Figure 1). The reliability of the herein proposed method was verified. Some embryos undergone treatment by tricaine, a cardiac anaesthetizing drug, in consequence of which a decrease of the heart rate is expected: the heartbeat regularity in tricaine- treated embryos determined from power spectral analysis decreased as compared to no-treated embryos. The results demonstrated that our method is able to assess the cardiac physiology, in term of heart rhythm, in zebrafish embryos

Overview of the design of the ITER heating neutral beam injectors

The heating neutral beam injectors (HNBs) of ITER are designed to deliver 16.7MWof 1 MeVD0 or 0.87 MeVH0 to the ITER plasma for up to 3600 s. They will be the most powerful neutral beam\uf0a0(NB) injectors ever, delivering higher energy NBs to the plasma in a tokamak for longer than any previous systems have done. The design of the HNBs is based on the acceleration and neutralisation of negative ions as the efficiency of conversion of accelerated positive ions is so low at the required energy that a realistic design is not possible, whereas the neutralisation ofH 12 andD 12 remains acceptable ( 4856%). The design of a long pulse negative ion based injector is inherently more complicated than that of short pulse positive ion based injectors because: \u2022 negative ions are harder to create so that they can be extracted and accelerated from the ion source; \u2022 electrons can be co-extracted from the ion source along with the negative ions, and their acceleration must be minimised to maintain an acceptable overall accelerator efficiency; \u2022 negative ions are easily lost by collisions with the background gas in the accelerator; \u2022 electrons created in the extractor and accelerator can impinge on the extraction and acceleration grids, leading to high power loads on the grids; \u2022 positive ions are created in the accelerator by ionisation of the background gas by the accelerated negative ions and the positive ions are back-accelerated into the ion source creating a massive power load to the ion source; \u2022 electrons that are co-accelerated with the negative ions can exit the accelerator and deposit power on various downstream beamline components. The design of the ITER HNBs is further complicated because ITER is a nuclear installation which will generate very large fluxes of neutrons and gamma rays. Consequently all the injector components have to survive in that harsh environment. Additionally the beamline components and theNBcell, where the beams are housed, will be activated and all maintenance will have to be performed remotely. This paper describes the design of theHNBinjectors, but not the associated power supplies, cooling system, cryogenic system etc, or the high voltage bushingwhich separates the vacuum of the beamline fromthehighpressureSF6 of the high voltage (1MV) transmission line, through which the power, gas and coolingwater are supplied to the beam source. Also themagnetic field reduction system is not described