2,364 research outputs found
A tomographic approach to non-Markovian master equations
We propose a procedure based on symplectic tomography for reconstructing the
unknown parameters of a convolutionless non-Markovian Gaussian noisy evolution.
Whenever the time-dependent master equation coefficients are given as a
function of some unknown time-independent parameters, we show that these
parameters can be reconstructed by means of a finite number of tomograms. Two
different approaches towards reconstruction, integral and differential, are
presented and applied to a benchmark model made of a harmonic oscillator
coupled to a bosonic bath. For this model the number of tomograms needed to
retrieve the unknown parameters is explicitly computed.Comment: 15 pages, 2 figure
Reconstruction of Markovian Master Equation parameters through symplectic tomography
In open quantum systems, phenomenological master equations with unknown
parameters are often introduced. Here we propose a time-independent procedure
based on quantum tomography to reconstruct the potentially unknown parameters
of a wide class of Markovian master equations. According to our scheme, the
system under investigation is initially prepared in a Gaussian state. At an
arbitrary time t, in order to retrieve the unknown coefficients one needs to
measure only a finite number (ten at maximum) of points along three
time-independent tomograms. Due to the limited amount of measurements required,
we expect our proposal to be especially suitable for experimental
implementations.Comment: 7 pages, 3 figure
On the Herdability of Linear Time-Invariant Systems with Special Topological Structures
In this paper, we investigate the herdability property, namely the capability
of a system to be driven towards the (interior of the) positive orthant, for
linear time-invariant state-space models. Herdability of certain matrix pairs
(A,B), where A is the adjacency matrix of a multi-agent network, and B is a
selection matrix that singles out a subset of the agents (the "network
leaders"), is explored. The cases when the graph associated with A, G(A), is
directed and clustering balanced (in particular, structurally balanced), or it
has a tree topology and there is a single leader, are investigated.Comment: Provisionally accepted in Automatica, currently under review. arXiv
admin note: substantial text overlap with arXiv:2108.0157
Modeling the Cooperative Process of Learning a Task
In this paper, we propose a mathematical model for a Transactive Memory
System (TMS) involved in the cooperative process of learning a task. The model
is based on an intertwined dynamics involving both the individuals level of
expertise and the interaction network among the cooperators. The model shows
that if all the agents are non-stubborn, then all of them are able to acquire
the competence of the most expert members of the group, asymptotically reaching
their level of proficiency. Conversely, when dealing with all stubborn agents,
the capability to pass on the task depends on the connectedness properties of
the interaction graph.Comment: Accepted for presentation at the European Control Conference (ECC
2022
Multi-dimensional extensions of the Hegselmann-Krause model
In this paper, we consider two multi-dimensional Hagselmann-Krause (HK)
models for opinion dynamics. The two models describe how individuals adjust
their opinions on multiple topics, based on the influence of their peers. The
models differ in the criterion according to which individuals decide whom they
want to be influenced from. In the average-based model, individuals compare
their average opinions on the various topics with those of the other
individuals and interact only with those individuals whose average opinions lie
within a confidence interval. For this model, we provide an alternative proof
for the contractivity of the range of opinions and show that the agents'
opinions reach consensus/clustering if and only if their average opinions do
so. In the uniform affinity model agents compare their opinions on every single
topic and influence each other only if, topic-wise, such opinions do not differ
more than a given tolerance. We identify conditions under which the uniform
affinity model enjoys the order-preservation property topic-wise and we prove
that the global range of opinions (and hence the range of opinions on every
single topic) are nonincreasing.Comment: Submitted to the 61st Conference on Decision and Control (CDC 2022),
Cancun, Mexic
Reconstruction of time-dependent coefficients: a check of approximation schemes for non-Markovian convolutionless dissipative generators
We propose a procedure to fully reconstruct the time-dependent coefficients
of convolutionless non-Markovian dissipative generators via a finite number of
experimental measurements. By combining a tomography based approach with a
proper data sampling, our proposal allows to relate the time-dependent
coefficients governing the dissipative evolution of a quantum system to
experimentally accessible quantities. The proposed scheme not only provides a
way to retrieve full information about potentially unknown dissipative
coefficients but also, most valuably, can be employed as a reliable consistency
test for the approximations involved in the theoretical derivation of a given
non-Markovian convolutionless master equation.Comment: 11 pages, 4 figures, revised version published on PR
Upper Limb Structural Anatomic Mechanisms of Protection (SAMPs)
Introduction Nature has provided living bodies with extraordinarily effective reparative mechanisms. Furthermore, the biological
processes involved in anatomical structures are built-up to protect life against external injuries. A series of these protective systems
in the upper limb are herein described. Material and Methods From 2009 to 2017, 864 fresh frozen cadaveric upper limbs were
dissected from the axilla to the fingers during the Italian Hand Society surgical anatomy dissection course. Results Arrangement
of anatomical structures in the upper limb is able to protect major life supporting organs. Conclusions External injuries affecting
the upper limb may cause damage to many important structures resulting in severe functional impairments. The layout of the
structures and the relationship between them are organized to preserve arteries integrity first, more than muscles and nerves. This
means, in our opinion, that these structures are organized to preserve life even if this has functional cost
Efficiency of biochar for reducing mobility of inorganic contaminants
Anthropogenic activities have produced numerous sites with extensive contamination close to residential areas.
Several physicochemical and biological remediation methods exist for remediation of metal contaminated soils
and lands, such as soil washing, soil flushing, phytoremediation, and electrokinetics.
Biochar (biologically derived charcoal) is produced by pyrolysis of biomasses under low oxygen conditions, and
it can be applied for recycling organic waste in soils.
The main objectives of the present study were to determine the possible use of biochar from forest ersidues (Populus nigra) in order to achieve a stabilization of inorganic contaminants by adsorption processes. Adsorption of
copper by biochar from dilute solutions showed a closer agreement with the Langmuir isotherm in a concentration
range 25-500 mM. The decontamination by biochar is very suitable because the treatment is passive and does not
require specialized equipment or extensive labor as compared to other remediation methods. Moreover, biochar
is also a possible carbon sink due to its long term storage in environment, thereby favouring mitigation of the
anthropic impact on environment
Childhood vaccinations: A pilot study on knowledge, attitudes and vaccine hesitancy in pregnant women
Background. The objective of this pilot study was to test a questionnaire aimed at assessing knowledge of and attitudes towards vaccination, as well as intention to vaccinate, among pregnant women.
Methods. The questionnaire was self-administered by 49 pregnant women attending antenatal classes at three Family Centers in Rome.
Results. Poor knowledge of vaccinations, inadequate attention from healthcare professionals, recurrent consultation of unreliable sources of information, and misconceptions about the side effects of vaccines, all contribute to vaccine hesitancy. Where appropriate, questionnaire sections were shown to be internally consistent.
Conclusion. The questionnaire proved reliable and is suitable for further studies
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