378 research outputs found
Non glassy ground-state in a long-range antiferromagnetic frustrated model in the hypercubic cell
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
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
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
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
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
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
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
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
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
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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