378 research outputs found

    Non glassy ground-state in a long-range antiferromagnetic frustrated model in the hypercubic cell

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    We analize the statistical mechanics of a long-range antiferromagnetic model defined on a D-dimensional hypercube, both at zero and finite temperatures. The associated Hamiltonian is derived from a recently proposed complexity measure of Boolean functions, in the context of neural networks learning processes. We show that, depending of the value of D, the system either presents a low temperature antiferromagnetic stable phase or the global antiferromagnetic order disappears at any temperature. In the last case the ground state is an infinitely degenerated non-glassy one, composed by two equal size anti-aligned antiferromagnetic domains. We also present some results for the ferromagnetic version of the model.Comment: 8 pages, 5 figure

    Los ADRS Chilenos y sus Implicancias en Precio y Varianza en sus Activos Subyacentes

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    The present paper analyzes the impact of Chilean ADR issues o­n the price and variance of their underlying securities. The results indicate that the impact of the international issue o­n the dual listed securities is similar to that suggested in the finan

    Tasas de Interés Nominal de Corto Plazo en Chile: Una Comparación Empírica de sus Modelos

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    This article examines different one-factor models of the short-term nominal interest rate in Chile, concluding that the models best describing this behavior are those that allow the rate volatility not to be constant, a conclusion similarly reached by CKLChan, karolyi, longstaff y sanders, método generalizado de momentos, reversión a la media

    Medición y Test del Impacto de Innovaciones en la Volatilidad de Índices Accionarios

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    This paper examines the most frequently used models of conditional variance in the estimation of stock returns and portfolios. The models are analyzed by various tests in order to measure their capabilities to explain variance. At the same time, the tests

    On Thermalization in Classical Scalar Field Theory

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    Thermalization of classical fields is investigated in a \phi^4 scalar field theory in 1+1 dimensions, discretized on a lattice. We numerically integrate the classical equations of motion using initial conditions sampled from various nonequilibrium probability distributions. Time-dependent expectation values of observables constructed from the canonical momentum are compared with thermal ones. It is found that a closed system, evolving from one initial condition, thermalizes to high precision in the thermodynamic limit, in a time-averaged sense. For ensembles consisting of many members with the same energy, we find that expectation values become stationary - and equal to the thermal values - in the limit of infinitely many members. Initial ensembles with a nonzero (noncanonical) spread in the energy density or other conserved quantities evolve to noncanonical stationary ensembles. In the case of a narrow spread, asymptotic values of primary observables are only mildly affected. In contrast, fluctuations and connected correlation functions will differ substantially from the canonical values. This raises doubts on the use of a straightforward expansion in terms of 1PI-vertex functions to study thermalization.Comment: 17 pages with 6 eps figure

    Mitigation of Automotive Control Modules Hardware Replacement-based Attacks Through Hardware Signature

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    Authentication of hardware modules connected through Controller Area Networks (CAN) in modern vehicles is becoming an increasing security issue. Untrusted modules introduced on the market may alter the secure boot infrastructure of a complex vehicle, thus completely compromising its security. This paper introduces the problem and highlights a preliminary idea for reaching better protection and preventing or limiting this category of attacks

    PSP Framework: A novel risk assessment method in compliance with ISO/SAE-21434

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    As more cars connect to the internet and other devices, the automotive market has become a lucrative target for cyberattacks. This has made the industry more vulnerable to security threats. As a result, car manufacturers and governments are working together to reduce risks and prevent cyberattacks in the automotive sector. However, existing attack feasibility models derived from the information technology field may not always provide accurate assessments of the potential risks faced by Vehicle Electronic Control Units in different operating conditions and domains. This paper introduces the PUNCH Softronix and Politecnico di Torino (PSP) framework to address this issue. This framework is designed to provide accurate assessments compatible with the attack feasibility models defined by the automotive product security standards. The PSP framework utilizes social sentiment analysis to evaluate the real threat risk levels

    LIN-MM: Multiplexed Message Authentication Code for Local Interconnect Network message authentication in road vehicles

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    The automotive market is profitable for cyberattacks with the constant shift toward interconnected vehicles. Electronic Control Units (ECUs) installed on cars often operate in a critical and hostile environment. Hence, both carmakers and governments have supported initiatives to mitigate risks and threats belonging to the automotive domain. The Local Interconnect Network (LIN) is one of the most used communication protocols in the automotive field. Today’s LIN buses have just a few light security mechanisms to assure integrity through Message Authentication Codes (MAC). However, several limitations with strong constraints make applying those techniques to LIN networks challenging, leaving several vehicles still unprotected. This paper presents LIN Multiplexed MAC (LIN-MM), a new approach for exploiting signal modulation to multiplex MAC data with standard LIN communication. LIN-MM allows for transmitting MAC payloads, maintaining full-back compatibility with all versions of the standard LIN protocol

    On a singular Fredholm-type integral equation arising in N=2 super Yang-Mills theories

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    In this work we study the Nekrasov-Shatashvili limit of the Nekrasov instanton partition function of Yang-Mills field theories with N=2 supersymmetry and gauge group SU(n). The theories are coupled with fundamental matter. The equation that determines the density of eigenvalues at the leading order in the saddle-point approximation is exactly solved. The dominating contribution to the instanton free energy is computed. The requirement that this energy is finite imposes quantization conditions on the parameters of the theory that are in agreement with analogous conditions that have been derived in previous works. Using methods borrowed from the theory of matrix models, a field theoretical expression of the full instanton partition function is derived. It is checked that in the Nekrasov-Shatashvili (thermodynamic) limit the action of the field theory obtained in this way reproduces exactly the equation of motion used in the saddle-point calculations.Comment: 16 pages, LaTeX + RevTex 4, no figures, final version accepted by Phys. Lett.

    Cold-active molecules for a sustainable preservation and restoration of historic-artistic manufacts

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    In the last decades biotechnology research provides sustainable alternatives to traditional procedures for preventive preservation of cultural assets. Recently, bioactive molecules (BMs) isolated from marine invertebrate organisms have been isolated and tested for bioremoval of protein layers (BMP) or to controlling microbial colonization (BMA), acting at temperature lower than 30°C. The Protease or Antimicrobial activity was tested on ad hoc assembled specimens and on different historic-artistic manufacts. In bio-removing protocol BMP molecules were applied as gelled solutions, in order to guarantees a selective action, respectful of constitutive materials and manufact integrity. Peculiarity of Protease bioactive molecules is the temperature of action, lower than 30°C. Instead, BMAs molecules have been tested to control bacteria and fungi colonization in laboratory specimens. In our hypothesis these novel molecules provide an important contribution to the development of innovative protocols safe both for the environment and conservator health, representing a valid alternative to traditional methods according to the preventive conservation and "Minimal Intervention" concept in restoration procedures
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