226 research outputs found
Can a City Be Relocated? Exploring the Metaphysics of Context- Dependency
This paper explores the Persistence Question about cities, that is, what is necessary and sufficient for two cities existing at different times to be numerically identical. We first show that we can possibly put an end to the existence of a city in a number of ways other than by physically destroying it, which reveals the metaphysics of cities to be partly different from that of ordinary objects. Then we focus in particular on the commonly perceived vulnerability of cities to imaginary relocation; and we make the hypothesis that cities do have among their essential properties that of being surrounded by a specific geographical context. Finally we investigate the pos- sibility that a city can survive relocation in virtue of the capacity of its geographical context to survive it in the first place. We suggest that city contexts may not be essentially context-dependent in turn, and outline a possible description of the cri- teria for their persistence over time
A low cost mobile mapping system (LCMMS) for field data acquisition: a potential use to validate aerial/satellite building damage assessment
Among the major natural disasters that occurred in 2010, the Haiti earthquake was a real turning point concerning the availability, dissemination and licensing of a huge quantity of geospatial data. In a few days several map products based on the analysis of remotely sensed data-sets were delivered to users. This demonstrated the need for reliable methods to validate the increasing variety of open source data and remote sensing-derived products for crisis management, with the aim to correctly spatially reference and interconnect these data with other global digital archives. As far as building damage assessment is concerned, the need for accurate field data to overcome the limitations of both vertical and oblique view satellite and aerial images was evident. To cope with the aforementioned need, a newly developed Low-Cost Mobile Mapping System (LCMMS) was deployed in Port-au-Prince (Haiti) and tested during a five-day survey in FebruaryMarch 2010. The system allows for acquisition of movies and single georeferenced frames by means of a transportable device easily installable (or adaptable) to every type of vehicle. It is composed of four webcams with a total field of view of about 180 degrees and one Global Positioning System (GPS) receiver, with the main aim to rapidly cover large areas for effective usage in emergency situations. The main technical features of the LCMMS, the operational use in the field (and related issues) and a potential approach to be adopted for the validation of satellite/aerial building damage assessments are thoroughly described in the articl
Exergoeconomic and Environmental Evaluation of a Ground Source Heat Pump System for Reducing the Fossil Fuel Dependence: A Case Study in Rome
By 2050, the European Commission aims to achieve a 90% reduction in greenhouse gas emissions within the construction sector due to new targets set for greenhouse gases by the Commission. One of the most effective solutions for mitigating the environmental impact of buildings is to integrate renewable-energy systems such as air-to-water heat pumps or geothermal heat pumps. Several works in the literature investigated the advantages of heat pumps, particularly ground source heat pumps, for specific contexts. Furthermore, the evaluation can encompass not only energy considerations but also exergetic aspects, and this paper makes a significant contribution to the latter. The study presented here applies exergy analysis to a geothermal heat pump system that is interconnected with photo-voltaic and solar collector systems in a building located in Rome. Feasibility and environmental assessments were also conducted. It is evident that the exergy efficiency obtained is much lower than the energy efficiency. The heat pump demonstrates higher exergy efficiency by producing high-temperature thermal power compared to a constant dead state at relatively low temperatures. Following the heat pump, the adiabatic mixer exhibits the second highest exergy efficiency, trailed by two heat exchangers. Compared to a conventional plant case, the money saved is EUR 16,772 per year, translating to a Payback Period of 23 years. Furthermore, the average annual reduction in fossil fuel emissions is estimated at 26.2 metric tons of CO2
Adversarial Attacks Against Uncertainty Quantification
Machine-learning models can be fooled by adversarial examples, i.e.,
carefully-crafted input perturbations that force models to output wrong
predictions. While uncertainty quantification has been recently proposed to
detect adversarial inputs, under the assumption that such attacks exhibit a
higher prediction uncertainty than pristine data, it has been shown that
adaptive attacks specifically aimed at reducing also the uncertainty estimate
can easily bypass this defense mechanism. In this work, we focus on a different
adversarial scenario in which the attacker is still interested in manipulating
the uncertainty estimate, but regardless of the correctness of the prediction;
in particular, the goal is to undermine the use of machine-learning models when
their outputs are consumed by a downstream module or by a human operator.
Following such direction, we: \textit{(i)} design a threat model for attacks
targeting uncertainty quantification; \textit{(ii)} devise different attack
strategies on conceptually different UQ techniques spanning for both
classification and semantic segmentation problems; \textit{(iii)} conduct a
first complete and extensive analysis to compare the differences between some
of the most employed UQ approaches under attack. Our extensive experimental
analysis shows that our attacks are more effective in manipulating uncertainty
quantification measures than attacks aimed to also induce misclassifications
LIBS analysis to define the alteration processes on the surface of ancient stones: the case study of Romanesque medieval monuments (Italy)
Weathering and bio-deterioration processes frequently affect the chromatic aspect of the stones used in the monuments. The surface alteration involves both physical modifications (e.g., increase of porosity) and chemical-mineralogical transformations of the rock, with formation of new secondary phases and deposition of the organic substances and inorganic solid phases (amorphous or crystalline particles).
This research aims to study the surface films of stones (i.e., basalts, pyroclastic rocks, limestone, marbles) used in some historical-cultural relevant Sardinian Romanesque churches (XI-XIV sec.) using LIBS and XRD analysis. These latter, together with petrographic analysis by polarized light microscopy in thin section, are useful to reconstruct the micro-stratigraphic aspects of different film levels.
The results highlight three different cases: i) chromatic alteration of the stone surface, ii) chemical-mineralogical alteration of stone with formation of coatings similar to the stone substrate, iii) chemical-mineralogical processes with the formation on the surface of secondary phases not related to the substrate, with the presence of Ca-oxalate (i.e. weddelite, whevellite). The presence of the Ca-oxalates, as noted in literature, is a testimony of application of organic substances on the surfaces themselves, with aesthetic purposes, to standardize or improve the color of the stone, or conservative, to limit the negative effects of weathering
Current Options for Visualization of Local Deformation in Modern Shape Analysis Applied to Paleobiological Case Studies
In modern shape analysis, deformation is quantified in different ways depending on the algorithms used and on the scale at which it is evaluated. While global affine and non-affine deformation components can be decoupled and computed using a variety of methods, the very local deformation can be considered, infinitesimally, as an affine deformation. The deformation gradient tensor F can be computed locally using a direct calculation by exploiting triangulation or tetrahedralization structures or by locally evaluating the first derivative of an appropriate interpolation function mapping the global deformation from the undeformed to the deformed state. A suitable function is represented by the thin plate spline (TPS) that separates affine from non-affine deformation components. F, also known as Jacobian matrix, encodes both the locally affine deformation and local rotation. This implies that it should be used for visualizing primary strain directions (PSDs) and deformation ellipses and ellipsoids on the target configuration. Using C = FTF allows, instead, one to compute PSD and to visualize them on the source configuration. Moreover, C allows the computation of the strain energy that can be evaluated and mapped locally at any point of a body using an interpolation function. In addition, it is possible, by exploiting the second-order Jacobian, to calculate the amount of the non-affine deformation in the neighborhood of the evaluation point by computing the body bending energy density encoded in the deformation. In this contribution, we present (i) the main computational methods for evaluating local deformation metrics, (ii) a number of different strategies to visualize them on both undeformed and deformed configurations, and (iii) the potential pitfalls in ignoring the actual three-dimensional nature of F when it is evaluated along a surface identified by a triangulation in three dimensions
AI Security and Safety: The PRALab Research Experience
We present here the main research topics and activities on security, safety, and robustness of machine learning models developed at the Pattern Recognition and Applications (PRA) Laboratory of the University of Cagliari. We have provided
pioneering contributions to this research area, being the first to demonstrate gradient-based attacks to craft adversarial examples and training data poisoning attacks. The findings of our research have significantly contributed not only to
identifying and characterizing vulnerabilities of such models in the context of real-world applications but also to the development of more trustworthy artificial intelligence and machine learning models. We are part of the ELSA network of
excellence for the development of safe and secure AI-based technologies, funded by the European Union
Impairment of acquisition of intravenous cocaine self-administration by RNA-interference of dopamine D1-receptors in the nucleus accumbens shell
Microdialysis during i.v. drug self-administration (SA) have implicated nucleus accumbens (NAc) shell DA in cocaine and heroin reinforcement. However, this correlative evidence has not been yet substantiated by experimental evidence obtained by studying the effect of selective manipulation of NAc shell DA transmission on cocaine and heroin SA. In order to investigate this issue, DA D1a receptor (D1aR) expression was impaired in the NAc shell and core by locally infusing lentiviral vectors (LV) expressing specific D1aR-siRNAs (LV-siRNAs). Control rats were infused in the same areas with LV expressing GFP. Fifteen days later, rats were trained to acquire i.v. cocaine or heroin self-administration (SA). At the end of behavioral experiments, in order to evaluate the effect of LV-siRNA on D1aR expression, rats were challenged with amphetamine and the brains were processed for immunohistochemical detection of c-Fos and D1aR. Control rats acquired i.v. cocaine and heroin SA. Infusion of LV-siRNAs in the medial NAc shell reduced D1aR density and the number of c-Fos positive nuclei in the NAc shell, while sparing the core, and prevented the acquisition of cocaine, but not heroin SA. In turn, LV-siRNAs infusion in the core reduced D1aR density and the number of c-Fos positive nuclei in the same area, while sparing the shell, and failed to affect acquisition of cocaine. The differential effect of LV impairment of NAc shell D1aR on cocaine and heroin SA indicates that NAc shell DA acting on D1aR specifically mediates cocaine reinforcement
Prospective Assessment of Health-Related Quality of Life in Pediatric Patients with Beta-Thalassemia following Hematopoietic Stem Cell Transplantation
Although hematopoietic stem cell transplantation (HSCT) has been widely used to treat pediatric patients with beta-thalassemia major, evidence showing whether this treatment improves health-related quality of life (HRQoL) is lacking. We used child-self and parent-proxy reports to prospectively evaluate HRQoL in 28 children with beta-thalassemia from Middle Eastern countries who underwent allogeneic HSCT in Italy. The PedsQL 4.0 Generic Core Scales were administered to patients and their parents 1 month before and 3, 6, and 18 months after transplantation. Two-year overall survival, thalassemia-free survival, mortality, and rejection were 89.3%, 78.6%, 10.9% and 14.3%, respectively. The cumulative incidence of acute and chronic graft-versus-host disease (GVHD) was 36% and 18%, respectively. Physical functioning declined significantly from baseline to 3 months after HSCT (median PedsQL score, 81.3 vs 62.5; P = .02), but then increased significantly up to 18 months after HSCT (median score, 93.7; P = .04). Agreement between child-self and parent-proxy ratings was high. Chronic GVHD was the most significant factor associated with lower HRQoL scores over time ( P = .02). The child-self and parent-proxy reports showed improved HRQoL in the children with beta-thalassemia after HSCT. Overall, our study provides preliminary evidence-based data to further support clinical decision making in this area
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