880 research outputs found
On Data Dissemination for Large-Scale Complex Critical Infrastructures
Middleware plays a key role for the achievement of the mission of future largescalecomplexcriticalinfrastructures, envisioned as federations of several heterogeneous systems over Internet. However, available approaches for datadissemination result still inadequate, since they are unable to scale and to jointly assure given QoS properties. In addition, the best-effort delivery strategy of Internet and the occurrence of node failures further exacerbate the correct and timely delivery of data, if the middleware is not equipped with means for tolerating such failures.
This paper presents a peer-to-peer approach for resilient and scalable datadissemination over large-scalecomplexcriticalinfrastructures. The approach is based on the adoption of epidemic dissemination algorithms between peer groups, combined with the semi-active replication of group leaders to tolerate failures and assure the resilient delivery of data, despite the increasing scale and heterogeneity of the federated system. The effectiveness of the approach is shown by means of extensive simulation experiments, based on Stochastic Activity Networks
Using a Remotely Piloted Aircraft System (RPAS) to analyze the stability of a natural rock slope
This paper describes the application of a rotary wing RPAS for monitoring the stability of a natural rock slope in the municipality of Vecchiano (Pisa, Italy). The slope under investigation is approximately oriented NNW-SSE and has a length of about 320 m; elevation ranges from about 7 to 80 m a.s.l.. The hill consists of stratified limestone, somewhere densely fractured, with dip direction predominantly oriented in a normal way respect to the slope. Fracture traces are present in variable lengths, from decimetre to metre, and penetrate inward the rock versant with thickness difficult to estimate, often exceeding one meter in depth. The intersection between different fracture systems and the slope surface generates rocky blocks and wedges of variable size that may be subject to phenomena of gravitational instability (with reference to the variation of hydraulic and dynamic conditions). Geometrical and structural info about the rock mass, necessary to perform the analysis of the slope stability, were obtained in this work from geo-referenced 3D point clouds acquired using photogrammetric and laser scanning techniques. In particular, a terrestrial laser scanning was carried out from two different point of view using a Leica Scanstation2. The laser survey created many shadows in the data due to the presence of vegetation in the lower parts of the slope and limiting the feasibility of geo-structural survey. To overcome such a limitation, we utilized a rotary wing Aibotix Aibot X6 RPAS geared with a Nikon D3200 camera. The drone flights were executed in manual modality and the images were acquired, according to the characteristics of the outcrops, under different acquisition angles. Furthermore, photos were captured very close to the versant (a few meters), allowing to produce a dense 3D point cloud (about 80 Ma points) by the image processing. A topographic survey was carried out in order to guarantee the necessary spatial accuracy to the process of images exterior orientation. The coordinates of GCPs were calculated through the post-processing of data collected by using two GPS receivers, operating in static modality, and a Total Station. The photogrammetric processing of image blocks allowed us to create the 3D point cloud, DTM, orthophoto, and 3D textured model with high level of cartographic detail. Discontinuities were deterministically characterized in terms of attitude, persistence, and spacing. Moreover, the main discontinuity sets were identified through a density analysis of attitudes in stereographic projection. In addition, the size and shape of potentially unstable blocks identified along the rock slope were measured. Finally, using additional data from traditional engineering-geological surveys executed in accessible outcrops, the kinematic and dynamic stability analysis of the rocky slope was performed. Results from this step have indicated the deterministic safety factors of rock blocks and wedges, and will be used by local Authorities to plan the protection works for safety guarantee. Results from this application show the great advantage of modern RPAS that can be successfully applied for the analysis of sub-vertical rocky slopes, especially in areas either difficult to access with traditional techniques or masked by the presence of vegetation
Bank-based or Market-based financial sources: which is better for the EU?
This paper examines the relationships between the financial structure and the economic performance of non-financial corporations in the European Union (EU). The analysis covers the 1999-2018 period, thus allowing us to consider both the different cyclical phases and the process of enlargement of the EU and the Euro Area (EA). We investigate how the relative weight of market-based and bank-based finance affects the real performances of non-financial corporations across countries. Our results indicate that market-based finance is more effective than bank-based finance in supporting the growth of gross value added and investments of these corporations. Our findings hold when considering a break for the financial crisis (2008-2009), and are confirmed via a panel VAR specification. They may suggest a need to pursue a new balance between markets and intermediaries in the EU and EA by strengthening the role of the non-banking segments of financial markets
Bridging business model and inter-organizational coordination mechanisms in the Italian wine industry
Purpose – The aim of this paper is to interpret the concept of a business model from the pattern of coordination mechanisms used by an Italian wine cooperative to manage its inter-organizational relationships.
Design/methodology/approach – The business model is taken as the structure and governance of the relationships between the focal firm and its exchange partners. The empirical analysis is based on a qualitative investigation, analyzing material collected at the Farming Cooperative Gran Cru.
Findings – Several different coordination mechanisms were used to rethink the firm customer value proposition, showing a very complex and dynamic inter-organizational system: process control mechanisms, knowledge suppliers and clan control mechanisms. The combination of mechanisms enables the firm to govern the extreme complexity of external complementarities and interdependence among activities and resources.
Practical implications – The study is particularly helpful to managers because wine entrepreneurs and managers can influence their networks’ features and strategies, as well as the mechanisms for governance of the relationships and extracting customer value.
Originality/value – The study seeks to enrich the debate on the strategy/structure fit by shifting the focus from the organizational to inter-organizational level of analysis. The analysis centers on boundary-spanning relationships between one wine firm and its partners and knowledge suppliers. This perspective brings business model analysis and inter-organizational design closer because variables of the business model – such as customer value – can be seen as combinations of inter-organizational coordination mechanisms
Teaching Theoretical Physics: the cases of Enrico Fermi and Ettore Majorana
We report on theoretical courses by Fermi and Majorana, giving evidence of
the first appearance and further development of Quantum Mechanics teaching in
Italy. On the basis of original documents, we make a comparison between Fermi's
and Majorana's approaches. A detailed analysis is carried out of Fermi's course
on Theoretical Physics attended by Majorana in 1927-28. Three (previously
unknown) programs on advanced Physics courses submitted by Majorana to the
University of Rome between 1933 and 1936 and the course he held in Naples in
1938 complete our analysis: Fermi's phenomenological approach resounded in
Majorana, who however combined it with a deeper theoretical approach, closer to
the modern way of presenting Quantum Mechanics.Comment: latex, 21 pages; a contribution in the centenary of the birth of
Ettore Majoran
A combustion-driven facility for hypersonic sustained flight simulation
This study reports on the development of a new Blowdown-Induction Facility driven by two different Oxygen-Fueled Guns. The facility has been conceived and realized to simulate different flow conditions in the context of hypersonic sustained flight. Here the underlying principles are illustrated critically, along with a focused description of the various facility subsystems, their interconnections and the procedures specifically conceived to overcome some of the technical complexities on which this facility relies. The facility performances are finally presented in relation to some prototype applications, together with an indication of the related limits, advantages and possible directions for future improvements
A new facility for hypersonic flow simulation driven by a high velocity oxygen fuel gun
The paper reports on the development of a new Vacuum High Velocity Oxy Fueled Facility (V-HVOF) for Aerothermodynamic and Propulsion applications. The related setup comprises unique equipment designed to test candidate materials for thermal protection systems and mimic experimentally conditions corresponding to hypersonic sustained flow. We illustrate critically the underlying principles, along with a focused description of the various facility subsystems, their interconnections and the specific procedures to be used to overcome some of the inherent complexities embedded in the overall theoretical and technical architecture on which the facility relies. Its performances are finally presented in relation to some prototype applications, together with the indication of the related limits, advantages and possible directions for future improvements
Microplastics, a Global Issue: Human Exposure through Environmental and Dietary Sources
: Plastic production has grown dramatically over the years. Microplastics (MPs) are formed
from the fragmentation of larger plastic debris by combining chemical, physical, and biological
processes and can degrade further to form nanoplastics (NPs). Because of their size, MPs and NPs are
bioavailable to many organisms and can reach humans through transport along the food chain. In
addition to the risk from ingesting MPs themselves, there are risks associated with the substances they
carry, such as pesticides, pathogenic microorganisms, and heavy metals, and with the additives added
to plastics to improve their characteristics. In addition, bioaccumulation and biomagnification can
cause a cumulative exposure effect for organisms at the top of the food chain and humans. Despite the
growing scientific interest in this emerging contaminant, the potential adverse effects remain unclear.
The aim of this review is to summarize the characteristics (size, shape, color, and properties) of
MPs in the environment, the primary sources, and the transport pathways in various environmental
compartments, and to shed more light on the ecological impact of MPs and the potential health effects
on organisms and humans by identifying human exposure pathways
Abnormal sensorimotor cortex and thalamo-cortical networks in familial adult myoclonic epilepsy type 2: pathophysiology and diagnostic implications
: Familial adult myoclonic epilepsy type 2 is a hereditary condition characterized by cortical tremor, myoclonus and epilepsy. It belongs to the spectrum of cortical myoclonus and the sensorimotor cortex hyperexcitability represents an important pathogenic mechanism underlying this condition. Besides pericentral cortical structures, the impairment of subcortical networks seems also to play a pathogenetic role, mainly via the thalamo-cortical pathway. However, the mechanisms underlying cortical-subcortical circuits dysfunction, as well as their impact on clinical manifestations, are still unknown. Therefore, the main aims of our study were to systematically study with an extensive electrophysiological battery, the cortical sensorimotor, as well as thalamo-cortical networks in genetically confirmed familial adult myoclonic epilepsy patients and to establish reliable neurophysiological biomarkers for the diagnosis. In 26 familial myoclonic epilepsy subjects, harbouring the intronic ATTTC repeat expansion in the StAR-related lipid transfer domain-containing 7 gene, 17 juvenile myoclonic epilepsy patients and 22 healthy controls, we evaluated the facilitatory and inhibitory circuits within the primary motor cortex using single and paired-pulse transcranial magnetic stimulation paradigms. We also probed the excitability of the somatosensory, as well as the thalamo-somatosensory cortex connection by using ad hoc somatosensory evoked potential protocols. The sensitivity and specificity of transcranial magnetic stimulation and somatosensory evoked potential metrics were derived from receiver operating curve analysis. Familial adult myoclonic epilepsy patients displayed increased facilitation and decreased inhibition within the sensorimotor cortex compared with juvenile myoclonic epilepsy patients (all P  0.05). Patients with a longer disease duration had more severe myoclonus (r = 0.467, P = 0.02) associated with a lower frequency (r = -0.607, P = 0.001) and higher power of tremor (r = 0.479, P = 0.02). Finally, familial adult myoclonic epilepsy was reliably diagnosed using transcranial magnetic stimulation, demonstrating its superiority as a diagnostic factor compared to somatosensory evoked potential measures. In conclusion, deficits of sensorimotor cortical and thalamo-cortical circuits are involved in the pathophysiology of familial adult myoclonic epilepsy even if these alterations are not associated with clinical severity. Transcranial magnetic stimulation-based measurements display an overall higher accuracy than somatosensory evoked potential parameters to reliably distinguish familial adult myoclonic epilepsy from juvenile myoclonic epilepsy and healthy controls
Do BRAF inhibitors select for populations with different disease progression kinetics?
Ipilimumab, an anti-CTLA-4 monoclonal antibody, has been shown to improve overall survival in patients with metastatic melanoma. Preliminary data suggest that patients who fail BRAF inhibitor treatment experience a very rapid progression of disease. Such selectivity for more rapid disease progression may mean these patients do not receive the same benefit from subsequent treatment with ipilimumab as patients without prior BRAF inhibitor treatment. The current challenge is focused on how to identify and approach the two populations of fast and slow progressors and recent hypothesis suggest that treatment choice could be guided by baseline risk factors. However, no data have yet defined which the best sequence is and more research is needed to identify predictors of response in patients with metastatic melanoma to help guide whether a BRAF inhibitor or ipilimumab should be used first in sequential therapy
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