426 research outputs found
Validity of spin wave theory for the quantum Heisenberg model
Spin wave theory is a key ingredient in our comprehension of quantum spin
systems, and is used successfully for understanding a wide range of magnetic
phenomena, including magnon condensation and stability of patterns in dipolar
systems. Nevertheless, several decades of research failed to establish the
validity of spin wave theory rigorously, even for the simplest models of
quantum spins. A rigorous justification of the method for the three-dimensional
quantum Heisenberg ferromagnet at low temperatures is presented here. We derive
sharp bounds on its free energy by combining a bosonic formulation of the model
introduced by Holstein and Primakoff with probabilistic estimates and operator
inequalities.Comment: 4 page
Generalized Disparate Impact for Configurable Fairness Solutions in ML
We make two contributions in the field of AI fairness over continuous
protected attributes. First, we show that the Hirschfeld-Gebelein-Renyi (HGR)
indicator (the only one currently available for such a case) is valuable but
subject to a few crucial limitations regarding semantics, interpretability, and
robustness. Second, we introduce a family of indicators that are: 1)
complementary to HGR in terms of semantics; 2) fully interpretable and
transparent; 3) robust over finite samples; 4) configurable to suit specific
applications. Our approach also allows us to define fine-grained constraints to
permit certain types of dependence and forbid others selectively. By expanding
the available options for continuous protected attributes, our approach
represents a significant contribution to the area of fair artificial
intelligence.Comment: to be published in ICML2
Unveiling the Soil beyond Definitions: A Holistic Framework for Sub-Regional Soil Quality Assessment and Spatial Planning
The issue of land/soil consumption and degradation has been extensively explored in international literature, yet a universally accepted definition of soil quality remains elusive. Over the decades, the scientific community has witnessed the evolution of the concept of land/soil quality, with varying nuances across different disciplines. The absence of a shared definition poses challenges in addressing local concerns and preserving the distinctiveness and well-being of the soil. The present paper seeks to fill this gap from the spatial planning perspective by proposing a soil quality detection framework tailored for the sub-regional spatial context, offering support in particular for local planning decisions. The concept of soil quality is approached comprehensively, and the indicators put forth are selected based on specific soil functions, services, or threats. To support this all-encompassing approach through a case study in the Italian context, this paper suggests integrating 11 datasets and 55 indicators. This extensive dataset aims to quantify and generate meaningful cartographic representations, offering a multifaceted and detailed understanding of soil quality within the sub-regional context. The goal is to establish a framework that facilitates a more holistic understanding of soil quality, aiding in effective spatial planning and policy-making processes
Micro-computed tomography for assessing the internal and external voids of bulk-fill composite restorations: A technical report
none6noopenTosco, Vincenzo; Monterubbianesi, Riccardo; Furlani, Michele; Giuliani, Alessandra; Putignano, Angelo; Orsini, GiovannaTosco, Vincenzo; Monterubbianesi, Riccardo; Furlani, Michele; Giuliani, Alessandra; Putignano, Angelo; Orsini, Giovann
Passive Automatic Identification System for Maritime Surveillance
This work describes the main achievements in the Passive AIS (P-AIS) project stage. The extensive literature research in the second chapter concludes performing additional in-situ experiments to estimate reliable target RCS and clutter reflectivity values at the AIS frequency range. The typical effective RCS distribution for ferry, yacht and small wooden boat is experimentally drawn; it reaches up to 26dBsm for the ferry. A clutter model is created, taking into account the literature and the experimental study. The AIS signal waveform is analyzed and the potential range and Doppler resolution is defined. More specifically, the signal ambiguity function gives approximately 20km of range resolution and 40Hz Doppler resolution. A coverage prediction tool, based on the bistatic radar equation, including the aforementioned clutter model; bistatic geometry theory; the effective target RCS; the antenna pattern; the AIS air interface parameters is made. The tool estimates the possible P-AIS coverage area. The work concludes that: even in case of high sea state, the sea is considered as a smooth surface reflection for low grazing angle of observation in the VHF range; the equidistant SNR areas change from Cassini shape to single oval receiver centered; the AIS energy provides excellent target “visibility” if the clutter is not considered. Discussions for further clutter reduction and system sophistication are arisen.JRC.G.4-Maritime affair
Analysis of gluten proteins composition during grain filling in two durum wheat cultivars submitted to two water regimes
Durum wheat ( Triticum turgidum L. subsp . durum) is one of the major crops in the Mediterranean basin, where water stress often occurs during grain filling which represents a critical stage for the synthesis and accumulation of storage proteins (gliadins and glutenins). The aim of the study is to evaluate, by two-dimensional gel electrophoresis (2DE SDS-PAGE), the storage proteins composition of two durum wheat cultivars (Ciccio and Svevo) cultivated in a growth chamber under two different water regimes (control and water deficit). At milk stage and physiological maturity, gluten proteins have been extracted and separated by 2DE SDS-PAGE. The analysis of the gels was performed by the software ImageMaster 2D Platinum (Amersham). The results showed differences in protein expression within the different gel regions between water regimes and cultivars; under water deficit the rate of protein accumulation was faster for all the protein regions, either at milk and physiological stage. Protein accumulation within high molecular weight (H) region resulted faster in Ciccio than in Svevo mainly in the control treatment. In the low molecular weight region between 48 and 35 kDa (L 48-35), the cultivar Ciccio showed a higher protein expression than Svevo. Furthermore under water deficit a marked increase in H region volume and a decrease in the L 48-35 region was observed only for Svevo; instead in Ciccio no change was observed showing this cultivar a greater stability on changing water regime. Further studies by the use of mass spectrometry are necessary to identify specific peptides relative to drought stress during grain filling as well as to investigate the relationships with technological quality
Effect of Arbuscular Mycorrhizal Fungal Seed Coating on Grain Protein and Mineral Composition of Old and Modern Bread Wheat Genotypes
The effect of arbuscular mycorrhizal fungi (AMF) on yield and quality was investigated on a set of seven bread wheat genotypes with varying years of release, including five old genotypes and two modern varieties. A two-year field trial was conducted in central Italy under rainfed con- ditions. The effect of AM fungal seed coating was proved by assessing the AM fungal root colonization and studied on agronomic and quality traits, and in particular on gluten-forming proteins and grain mineral composition. AMF seed coating led to a general yield improvement in old geno- types (+24%). Concerning the effects on grain quality, while modern genotypes showed an increase in protein content (+16%), in the old ones an improvement of gluten quality was observed, with an increased proportion of HMW-GS from +17% to +92%. The gluten index results were mostly influenced by HMW-GS allelic configuration and amount, showing a significant correlation with gliadin- to-glutenin ratio and HMW-GS to LMW-GS. Concerning mineral uptake, AM fungal treatment de- termined a general increase in P content, which was more marked in the modern group (+44%). Furthermore, AMF significantly increased mean Fe concentration in Verna (+53%) and Bologna (+45%). Finally, phytate content did not increase with AMF, without affecting mineral bioavailability
The symmetric 3D organization of connective tissue around implant abutment: a key-issue to prevent bone resorption
Symmetric and well-organized connective tissues around the longitudinal implant axis were hypothesized to decrease early bone resorption by reducing inflammatory cell infiltration. Previous studies that referred to the connective tissue around implant and abutments were based
on two-dimensional investigations; however, only advanced three-dimensional characterizations could evidence the organization of connective tissue microarchitecture in the attempt of finding new strategies to reduce inflammatory cell infiltration. We retrieved three implants with a cone morse implant–abutment connection from patients; they were investigated by high-resolution X-ray phase-contrast microtomography, cross-linking the obtained information with histologic results. We observed transverse and longitudinal orientated collagen bundles intertwining with each other. In the longitudinal planes, it was observed that the closer the fiber bundles were to the implant, the more symmetric and regular their course was. The transverse bundles of collagen fibers were observed as semicircular, intersecting in the lamina propria of the mucosa and ending in the oral epithelium. No collagen fibers were found radial to the implant surface. This intertwining three-dimensional pattern seems to favor the stabilization of the soft tissues around the implants, preventing inflammatory cell apical migration and, consequently, preventing bone resorption and implant failure. This fact, according to the authors’ best knowledge, has never been reported in the literature and might be due to the physical forces acting on fibroblasts and on the collagen produced by the fibroblasts themselves, in areas close to the implant and to the symmetric geometry of the implant itself
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