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

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

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

Feynman problem in the noncommutative case

In the context of the Feynman's derivation of electrodynamics, we show that noncommutativity allows other particle dynamics than the standard formalism of electrodynamics.Comment: latex, 7 pages, no figure

A Multi Agent Model for the Limit Order Book Dynamics

In the present work we introduce a novel multi-agent model with the aim to reproduce the dynamics of a double auction market at microscopic time scale through a faithful simulation of the matching mechanics in the limit order book. The agents follow a noise decision making process where their actions are related to a stochastic variable, "the market sentiment", which we define as a mixture of public and private information. The model, despite making just few basic assumptions over the trading strategies of the agents, is able to reproduce several empirical features of the high-frequency dynamics of the market microstructure not only related to the price movements but also to the deposition of the orders in the book.Comment: 20 pages, 11 figures, in press European Physical Journal B (EPJB

Lithium-Metal Free Sulfur Battery Based on Waste Biomass Anode and Nano-Sized Li2S Cathode

The realization of a stable lithium-metal free (LiMF) sulfur battery based on amorphous carbon anode and lithium sulfide (Li2S) cathode is here reported. In particular, a biomass waste originating full-cell combining a carbonized brewer's spent grain (CBSG) biochar anode with a Li2S-graphene composite cathode (Li2S70Gr30) is proposed. This design is particularly attractive for applying a cost-effective, high performance, environment friendly, and safe anode material, as an alternative to standard graphite and metallic lithium in emerging battery technologies. The anodic and cathodic materials are characterized in terms of structure, morphology and composition through X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron and Raman spectroscopies. Furthermore, an electrochemical characterization comprising galvanostatic cycling, rate capability and cyclic voltammetry tests were carried out both in half-cell and full-cell configurations. The systematic investigation reveals that unlike graphite, the biochar electrode displays good compatibility with the electrolyte typically employed in sulfur batteries. The CBSG/Li2S70Gr30 full-cell demonstrates an initial charge and discharge capacities of 726 and 537 mAh g−1, respectively, at 0.05C with a coulombic efficiency of 74%. Moreover, it discloses a reversible capacity of 330 mAh g−1 (0.1C) after over 300 cycles. Based on these achievements, the CBSG/Li2S70Gr30 battery system can be considered as a promising energy storage solution for electric vehicles (EVs), especially when taking into account its easy scalability to an industrial level. © 2022 The Authors. Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University

Quantum Limits in Interferometric GW Antennas

We discuss a model for interferometric GW antennas illuminated by a laser beam and a vacuum squeezed field. The sensitivity of the antenna will depend on the properties of the radiation entering the two ports and on the optical characteristics of the interferometer components, e.g. mirrors, beam-splitter, lenses