2,436 research outputs found
Adaptability Checking in Multi-Level Complex Systems
A hierarchical model for multi-level adaptive systems is built on two basic
levels: a lower behavioural level B accounting for the actual behaviour of the
system and an upper structural level S describing the adaptation dynamics of
the system. The behavioural level is modelled as a state machine and the
structural level as a higher-order system whose states have associated logical
formulas (constraints) over observables of the behavioural level. S is used to
capture the global and stable features of B, by a defining set of allowed
behaviours. The adaptation semantics is such that the upper S level imposes
constraints on the lower B level, which has to adapt whenever it no longer can
satisfy them. In this context, we introduce weak and strong adaptabil- ity,
i.e. the ability of a system to adapt for some evolution paths or for all
possible evolutions, respectively. We provide a relational characterisation for
these two notions and we show that adaptability checking, i.e. deciding if a
system is weak or strong adaptable, can be reduced to a CTL model checking
problem. We apply the model and the theoretical results to the case study of
motion control of autonomous transport vehicles.Comment: 57 page, 10 figures, research papaer, submitte
On the ISW-cluster cross-correlation in future surveys
We investigate the cosmological information contained in the
cross-correlation between the Integrated Sachs-Wolfe (ISW) of the Cosmic
Microwave Background (CMB) anisotropy pattern and galaxy clusters from future
wide surveys. Future surveys will provide cluster catalogues with a number of
objects comparable with galaxy catalogues currently used for the detection of
the ISW signal by cross-correlation with the CMB anisotropy pattern. By
computing the angular power spectra of clusters and the corresponding
cross-correlation with CMB, we perform a signal-to-noise ratio (SNR) analysis
for the ISW detection as expected from the eROSITA and the Euclid space
missions. We discuss the dependence of the SNR of the ISW-cluster
cross-correlation on the specifications of the catalogues and on the reference
cosmology. We forecast that the SNRs for ISW-cluster cross-correlation are
alightly smaller compared to those which can be obtained from future galaxy
surveys but the signal is expected to be detected at high significance, i.e.
more than . We also forecast the joint constraints on parameters
of model extensions of the concordance CDM cosmology by combining CMB
and the ISW-cluster cross-correlation.Comment: 12 pages, 10 figures. Matches version accepted in MNRA
Conformal Quantitative Predictive Monitoring of STL Requirements for Stochastic Processes
We consider the problem of predictive monitoring (PM), i.e., predicting at
runtime the satisfaction of a desired property from the current system's state.
Due to its relevance for runtime safety assurance and online control, PM
methods need to be efficient to enable timely interventions against predicted
violations, while providing correctness guarantees. We introduce
\textit{quantitative predictive monitoring (QPM)}, the first PM method to
support stochastic processes and rich specifications given in Signal Temporal
Logic (STL). Unlike most of the existing PM techniques that predict whether or
not some property is satisfied, QPM provides a quantitative measure of
satisfaction by predicting the quantitative (aka robust) STL semantics of
. QPM derives prediction intervals that are highly efficient to compute
and with probabilistic guarantees, in that the intervals cover with arbitrary
probability the STL robustness values relative to the stochastic evolution of
the system. To do so, we take a machine-learning approach and leverage recent
advances in conformal inference for quantile regression, thereby avoiding
expensive Monte-Carlo simulations at runtime to estimate the intervals. We also
show how our monitors can be combined in a compositional manner to handle
composite formulas, without retraining the predictors nor sacrificing the
guarantees. We demonstrate the effectiveness and scalability of QPM over a
benchmark of four discrete-time stochastic processes with varying degrees of
complexity
Benchmarking Evolutionary Community Detection Algorithms in Dynamic Networks
In dynamic complex networks, entities interact and form network communities
that evolve over time. Among the many static Community Detection (CD)
solutions, the modularity-based Louvain, or Greedy Modularity Algorithm (GMA),
is widely employed in real-world applications due to its intuitiveness and
scalability. Nevertheless, addressing CD in dynamic graphs remains an open
problem, since the evolution of the network connections may poison the
identification of communities, which may be evolving at a slower pace. Hence,
naively applying GMA to successive network snapshots may lead to temporal
inconsistencies in the communities. Two evolutionary adaptations of GMA, sGMA
and GMA, have been proposed to tackle this problem. Yet, evaluating the
performance of these methods and understanding to which scenarios each one is
better suited is challenging because of the lack of a comprehensive set of
metrics and a consistent ground truth. To address these challenges, we propose
(i) a benchmarking framework for evolutionary CD algorithms in dynamic networks
and (ii) a generalised modularity-based approach (NeGMA). Our framework allows
us to generate synthetic community-structured graphs and design evolving
scenarios with nine basic graph transformations occurring at different rates.
We evaluate performance through three metrics we define, i.e. Correctness,
Delay, and Stability. Our findings reveal that GMA is well-suited for
detecting intermittent transformations, but struggles with abrupt changes; sGMA
achieves superior stability, but fails to detect emerging communities; and
NeGMA appears a well-balanced solution, excelling in responsiveness and
instantaneous transformations detection.Comment: Accepted at the 4th Workshop on Graphs and more Complex structures
for Learning and Reasoning (GCLR) at AAAI 202
On the Hybridization of Geometric Semantic GP with Gradient-based Optimizers
Pietropolli, G., Manzoni, L., Paoletti, A., & Castelli, M. (2023). On the Hybridization of Geometric Semantic GP with Gradient-based Optimizers. Genetic Programming And Evolvable Machines, 24(2 Special Issue on Highlights of Genetic Programming 2022 Events), 1-20. [16]. https://doi.org/10.21203/rs.3.rs-2229748/v1, https://doi.org/10.1007/s10710-023-09463-1---Open access funding provided by Università degli Studi di Trieste within the CRUI-CARE Agreement. This work was supported by national funds through FCT (Fundação para a Ciência e a Tecnologia), under the Project—UIDB/04152/2020—Centro de Investigação em Gestão de Informação (MagIC)/NOVA IMSGeometric semantic genetic programming (GSGP) is a popular form of GP where the effect of crossover and mutation can be expressed as geometric operations on a semantic space. A recent study showed that GSGP can be hybridized with a standard gradient-based optimized, Adam, commonly used in training artificial neural networks.We expand upon that work by considering more gradient-based optimizers, a deeper investigation of their parameters, how the hybridization is performed, and a more comprehensive set of benchmark problems. With the correct choice of hyperparameters, this hybridization improves the performances of GSGP and allows it to reach the same fitness values with fewer fitness evaluations.publishersversionepub_ahead_of_prin
Statistical Guarantees for the Robustness of Bayesian Neural Networks
We introduce a probabilistic robustness measure for Bayesian Neural Networks
(BNNs), defined as the probability that, given a test point, there exists a
point within a bounded set such that the BNN prediction differs between the
two. Such a measure can be used, for instance, to quantify the probability of
the existence of adversarial examples. Building on statistical verification
techniques for probabilistic models, we develop a framework that allows us to
estimate probabilistic robustness for a BNN with statistical guarantees, i.e.,
with a priori error and confidence bounds. We provide experimental comparison
for several approximate BNN inference techniques on image classification tasks
associated to MNIST and a two-class subset of the GTSRB dataset. Our results
enable quantification of uncertainty of BNN predictions in adversarial
settings.Comment: 9 pages, 6 figure
The Mediterranean European hake, Merluccius merluccius: Detecting drivers influencing the Anisakis spp. larvae distribution
The European hake Merluccius merluccius is one of the most commercially important and widely distributed fish
species, occurring both in European and Mediterranean Sea fisheries. We analyzed the distribution and infection
rates of different species of Anisakis in M. merluccius (N = 1130 hakes), by site of infection in the fish host
(viscera, dorsal and ventral fillets) from 13 different fishing grounds of the Mediterranean Sea (FAO area 37).
The fillets were examined using the UV-Press method. A large number of Anisakis specimens (N = 877) were
identified by diagnostic allozymes, sequence analysis of the partial EF1 α-1 region of nDNA and mtDNA cox2
gene. Among these, 813 larvae corresponded to A. pegreffii, 62 to A. physeteris, 1 to A. simplex (s. s.), whereas one
resulted as a F1 hybrid between A. pegreffii and A. simplex (s. s.). Remarkably high levels of infection with A.
pegreffii were recorded in hakes from the Adriatic/Ionian Sea compared to the fish of similar length obtained
from the western Mediterranean fishing grounds. A positive correlation between fish length and abundance of A.
pegreffii was observed. Concerning the localization of A. pegreffii larvae in the fish, 28.3% were detected in the
liver, 62.9% in the rest of the viscera, 6.6% in the ventral part of the flesh, whereas 2.1% in the dorsal flesh
HDAC-inhibitor (S)-8 disrupts HDAC6-PP1 complex prompting A375 melanoma cell growth arrest and apoptosis.
Histone deacetylase inhibitors (HDACi) are agents capable of inducing growth arrest and apoptosis in different tumour cell types. Previously, we reported a series of novel HDACi obtained by hybridizing SAHA or oxamflatin with 1,4-benzodiazepines. Some of these hybrids proved effective against haematological and solid cancer cells and, above all, compound (S)-8 has emerged for its activities in various biological systems. Here, we describe the effectiveness of (S)-8 against highly metastatic human A375 melanoma cells by using normal PIG1 melanocytes as control. (S)-8 prompted: acetylation of histones H3/H4 and α-tubulin; G(0)/G(1) and G(2)/M cell cycle arrest by rising p21 and hypophos-phorylated RB levels; apoptosis involving the cleavage of PARP and caspase 9, BAD protein augmentation and cytochrome c release; decrease in cell motility, invasiveness and pro-angiogenic potential as shown by results of wound-healing assay, down-regulation of MMP-2 and VEGF-A/VEGF-R2, besides TIMP-1/TIMP-2 up-regulation; and also intracellular accumulation of melanin and neutral lipids. The pan-caspase inhibitor Z-VAD-fmk, but not the antioxidant N-acetyl-cysteine, contrasted these events. Mechanistically, (S)-8 allows the disruption of cytoplasmic HDAC6-protein phosphatase 1 (PP1) complex in A375 cells thus releasing the active PP1 that dephosphorylates AKT and blocks its downstream pro-survival signalling. This view is consistent with results obtained by: inhibiting PP1 with Calyculin A; using PPP1R2-transfected cells with impaired PP1 activity; monitoring drug-induced HDAC6-PP1 complex re-shuffling; and, abrogating HDAC6 expression with specific siRNA. Altogether, (S)-8 proved very effective against melanoma A375 cells, but not normal melanocytes, and safe to normal mice thus offering attractive clinical prospects for treating this aggressive malignancy
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