86,762 research outputs found
The dual role of nod-like receptors in mucosal innate immunity and chronic intestinal inflammation
No full textNucleotide-binding and oligomerization domain NOD-like receptors (NLRs) are highly conserved cytosolic pattern recognition receptors that play, in combination with toll-like receptors, a critical role in innate immunity and inflammation. These proteins are characterized by a central oligomerization domain termed nucleotide-binding domain, and a protein interaction domain containing leucine-rich repeats. Some NLRs, including NOD1 and NOD2, sense the cytosolic presence of conserved bacterial molecular signatures and drive the activation of mitogen-activated protein kinase and the transcription factor NF-κB. A different set of NLRs induces caspase-1 activation through the assembly of large protein complexes known as inflammasomes. Activation of NLR proteins results in secretion of pro-inflammatory cytokines and subsequent inflammatory responses. The critical role of NLRs in innate immunity is underscored by the fact that polymorphisms within their genes are implicated in the development of several immune-mediated diseases, including inflammatory bowel disease. Over the past few years, the role of NLRs in intestinal homeostasis has been highlighted, however the mechanism by which dysfunction in these proteins leads to aberrant inflammation is still the focus of much investigation. The purpose of this review is to systematically evaluate the function of NLRs in mucosal innate immunity and understand how genetic or functional alterations in these components can lead to the disruption of intestinal homeostasis, and the subsequent development of chronic inflammation. © 2014 Corridoni, Arseneau, Cifone and Cominelli
Optimal design of broadband, low-directivity graded index acoustic lenses for underwater communication
No full textManipulating underwater pressure waves is crucial for marine exploration, as electromagnetic signals are strongly absorbed in water. However, the multi-path phenomenon complicates the accurate capture of acoustic waves by receivers. Although graded index lenses, based on metamaterials with smoothly varying properties, successfully focus pressure waves, they tend to have high directivity, which hinders practical application. This work introduces three 2D acoustic lenses made from a metamaterial composed of solid inclusions in water. We propose an optimization scheme where the pressure dynamics is governed by Helmholtz's equation, with control parameters affecting each lens cell's density and bulk modulus. Through an appropriate cost function, the optimization encourages a broadband, low-directivity lens. The large-scale optimization is solved using the Lagrangian approach, which provides an analytical expression for the cost gradient. This scheme avoids the need for a separate discretization step, allowing the design to transition directly from the desired smooth refractive index to a practical lattice structure. As a result, the optimized lens closely aligns with real-world behavior. The homogenized numerical model is validated against finite elements, which considers acoustic-elastic coupling at the microstructure level. When homogenization holds, this approach proves to be an effective design tool for achieving broadband, low-directivity acoustic lenses
Exposing the CSI: A Systematic Investigation of CSI-based Wi-Fi Sensing Capabilities and Limitations
No full textThanks to the ubiquitous deployment of Wi-Fi hotspots, channel state information (CSI)-based Wi-Fi sensing can unleash game-changing applications in many fields, such as healthcare, security, and entertainment. However, despite one decade of active research on Wi-Fi sensing, most existing work only considers legacy IEEE 802.11n devices, often in particular and strictly-controlled environments. Worse yet, there is a fundamental lack of understanding of the impact on CSI-based sensing of modern Wi-Fi features, such as 160-MHz bandwidth, multiple-input multiple-output (MIMO) transmissions, and increased spectral resolution in IEEE 802.11ax (Wi-Fi 6). This work aims to shed light on the impact of Wi-Fi 6 features on the sensing performance and to create a benchmark for future research on Wi-Fi sensing. To this end, we perform an extensive CSI data collection campaign involving 3 individuals, 3 environments, and 12 activities, using Wi-Fi 6 signals. An anonymized ground truth obtained through video recording accompanies our 80-GB dataset, which contains almost two hours of CSI data from three collectors. We leverage our dataset to dissect the performance of a state-of-The-Art sensing framework across different environments and individuals. Our key findings suggest that (i) MIMO transmissions and higher spectral resolution might be more beneficial than larger bandwidth for sensing applications; (ii) there is a pressing need to standardize research on Wi-Fi sensing because the path towards a truly environment-independent framework is still uncertain. To ease the experiments' replicability and address the current lack of Wi-Fi 6 CSI datasets, we release our 80-GB dataset to the community
Socialità, alienazione e abitudini: ipotesi sociologiche sulla pandemia da Covid-19
No full textAll’inizio del 2020, la pandemia da COVID-19 ha squassato in poche settimane quelle che sembravano alcune tendenze inarrestabili nell'esistenza di tutti noi, e che implicavano un’inarrestabile crescita delle occasioni di mobilità e di socializzazione. Il distanziamento sociale prolungato imposto dalle misure sanitarie ha rappresentato un “esperimento naturale” che oggi può essere indagato sotto numerosi punti di vista. In questo articolo vengono analizzate le dinamiche di riduzione della socialità, i fenomeni di alienazione e di anomia, nonché le modifiche temporanee o permanenti che la prima pandemia del mondo globalizzato moderno potrebbe avere indotto nelle nostre pratiche sociali
Design of an Acoustic Luneburg Lens via Topology Optimization of Pentamode Lattice
No full textThis study introduces an automated topology optimization approach for designing a pentamode metamaterial. We validate the method designing a graded index (GRIN) 2D Luneburg lens for underwater acoustics. This approach ensures each cell meets precise refractive index requirements, maintaining constant impedance to prevent internal reflections and minimizing shear modulus for a fluid-like behavior
Non Intrusive Wi-Fi CSI Obfuscation Against Active Localization Attacks
No full textChannel State Information (CSI) based localization with 802.11 has been proven feasible in multiple scenarios and is becoming a serious threat to people privacy in work spaces, at home, and maybe even outdoors, even if outdoors experiments proving the feasibility are still not available. Countering unauthorized localization without hampering communications is a nontrivial task, although some very recent works suggest that it is feasible with marginal modification of the 802.11 transmission chain, but this requires modifying 802.11 devices. Furthermore, if the attacker controls two devices and not only a receiver, transmission side signal manipulation cannot help. This work explores the possibility of countering CSI based localization with an active device that, instead of jamming signals to avoid that a malicious receiver exploits CSI information to locate a person, superimpose on frames a copy of the same frame signal whose goal is not destroying reception as in jamming, but only obfuscate the location relevant information carried by the CSI. A prototype implementation and early results looks promising; they show feasibility of location obfuscation with high efficiency and excellent preservation of communication performance, paving the road for further research and improved users privacy
Phytic acid and transporters : what can we learn from low phytic acid mutants
No full textPhytic acid has two main roles in plant tissues: Storage of phosphorus and regulation of different cellular processes. From a nutritional point of view, it is considered an antinutritional compound because, being a cation chelator, its presence reduces mineral bioavailability from the diet. In recent decades, the development of low phytic acid (lpa) mutants has been an important goal for nutritional seed quality improvement, mainly in cereals and legumes. Different lpa mutations affect phytic acid biosynthetic genes. However, other lpa mutations isolated so far, affect genes coding for three classes of transporters: A specific group of ABCC type vacuolar transporters, putative sulfate transporters, and phosphate transporters. In the present review, we summarize advances in the characterization of these transporters in cereals and legumes. Particularly, we describe genes, proteins, and mutants for these different transporters, and we report data of in silico analysis aimed at identifying the putative orthologs in some other cereal and legume species. Finally, we comment on the advantage of using such types of mutants for crop biofortification and on their possible utility to unravel links between phosphorus and sulfur metabolism (phosphate and sulfate homeostasis crosstalk)
AntiSense: Standard-compliant CSI obfuscation against unauthorized Wi-Fi sensing
No full textChannel State Information (CSI)-based localization with 802.11 has been proven feasible in multiple scenarios and is becoming a serious threat to people's privacy in workplaces, at home, and maybe even outdoors. Countering unauthorized localization without hampering communications is a non-trivial task, although some very recent works suggest that it is feasible with marginal modification of the 802.11 transmission chain, but this requires modifying 802.11 devices. Furthermore, if the attacker controls two devices and not just a receiver, transmission side signal manipulation cannot help. This work explores the possibility of countering CSI based localization with an active device that, instead of jamming signals to avoid that a malicious receiver exploits CSI information to locate a person, superimpose on frames a copy of the same frame signal whose goal is not destroying reception as in jamming, but only obfuscate the location-relevant information carried by the CSI. A prototype implementation and early results look promising; they show the feasibility of location obfuscation with high efficiency and excellent preservation of communication performance, and indicate that the technique works both against passive attacks, where the attacker controls only a receiver, and active ones, where he/she controls both a transmitter and a receiver. These results pave the road for further research on smart spaces that preserve users’ privacy with a technical solution and not only via legal prescriptions
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