Quantization Of Spin Direction For Solitary Waves In A Uniform Magnetic Field

It is known that there are nonlinear wave equations with localized solitary wave solutions. Some of these solitary waves are stable (with respect to a small perturbation of initial data) and have nonzero spin (nonzero intrinsic angular momentum in the center of momentum frame). In this paper we consider vector-valued solitary wave solutions to a nonlinear Klein-Gordon equation and investigate the behavior of these spinning solitary waves under the influence of an externally imposed uniform magnetic field. We find that the only stationary spinning solitary wave solutions have spin parallel or anti-parallel to the magnetic field direction.Comment: 4 page

Risk assessment illuminotecnico in ambiente ospedaliero: il caso di studio dell'Ospedale "Felice Lotti" di Pontedera

Nella presente Tesi è stato esaminato il risk assessment illuminotecnico nel caso di studio dell’Ospedale “Felice Lotti” di Pontedera dove sono state effettuate valutazioni del rischio in 9 ambienti opportunamente selezionati. Le misurazioni effettuate con luxmetro e luminanzometro sono state elaborate secondo il metodo di valutazione del rischio, messo a punto nel corso del Piano Mirato Triennale per l’Area Tematica 3, che prevede l’utilizzo di fattori di rischio con l’attribuzione di un coefficiente di scostamento e di un coefficiente di pertinenza, dal cui prodotto si ottiene un indice di rilevanza. Nei locali considerati sono stati individuati i fattori di rischio che presentavano i valori più elevati dell’indice di rilevanza e sono state elaborate delle simulazioni di progetto illuminotecnico con l’ausilio del software Dialux 4.11 per risolvere queste criticità

Protein Arginine Deiminases: a novel mechanism of leukocyte trafficking under physiological and pathological conditions

Protein arginine deiminases (PADs) are a class of Ca2+ dependent cysteine hydrolases that catalyze a protein post-translational modification known as citrullination, where a positive protein-bound arginine residue is converted into a neutral unconventional citrulline residue. The reaction results in a shift of protein charge from positive to neutral, which dramatically impacts the structure, conformation, and function of proteins as well as intra/intermolecular interactions. Citrullination represents an important regulatory mechanism affecting several physiological cellular processes, such as gene expression, cell differentiation, apoptosis, and inflammatory immune responses. Among the PAD family members, PAD2 and PAD4, which are the only isoforms expressed by immune cells, have attracted considerable interest due to their role in producing neutrophil extracellular traps (NETs) and playing a detrimental role in a wide range of diseases such as Rheumatoid Arthritis, Ulcerative Colitis, Systemic Lupus Erythematosus, Multiple Sclerosis, and Alzheimer's Disease. Pharmacological PAD inhibition has brought beneficial therapeutic results in animal models of these pathologies since it leads to an amelioration of the disease-dependent inflammation and reduces immune cell accumulation and tissue damage. However, how PAD2 and PAD4 isoforms directly affect immune cell trafficking in the context of inflammation has not yet been studied. Hence, this project investigated the role of PAD-dependent citrullination in leukocyte adhesive activity under physiological and pathological conditions. We first treated neutrophils and lymphocytes with different concentrations of BB-Cl-amidine, a pan PAD inhibitor, and GSK199, which induces PAD4 specific blockade, and we studied the effect of cell treatment on \uf0622- integrin-dependent adhesion. Our data showed that PAD inhibitors reduce integrin activation and binding to endothelial ligands upon stimulation in vitro with chemokines, suggesting a role for PADs in rapid leukocyte adhesion mediated by \uf0622 integrins. In addition,, we demonstrated that BB-Cl-amidine also blocked lymphocyte \uf0621-integrin-dependent adhesion on VCAM-1 counterligand, suggesting that PADs are involved in controlling signaling pathways common to both \uf0622 and \uf0621 integrin activation. To exclude potential unspecific effects exerted by PAD inhibitors, we confirmed the data obtained with the pharmacological approach and showed that mRNA silencing of PADs blocks integrin-dependent adhesion in vitro, further confirming the involvement of PADs in leukocyte adhesion. To characterize more in detail the role of PADs in adhesion induction, we studied LFA-1 conformational changes triggered by chemoattractants and found that treatment with BB-Cl-amidine and GSK-199 completely prevented integrin transition to more extended conformations, suggesting a role for PADs in integrin affinity increase leading to leukocyte adhesion. Considering the function of PAD2 and PAD4 in NET release and our previous data demonstrating a role for neutrophils in animal models of Alzheimer's disease, we next investigated the effect of PAD blockade in 3xTg-AD mice, which develop both amyloid and tau pathologies. We treated the 3xTg-AD mice with BB-Cl-amidine, and the results from behavioural tests showed that PAD inhibition significantly rescues spatial working memory and associative learning compared to untreated control mice. Histopathological analysis confirmed the beneficial effects of PAD inhibitors since microglial activation, amyloid accumulation, and tau phosphorylation were strongly reduced after PAD blockade. Finally, we quantified brain-infiltrating leukocytes in BB-Cl-amidine treated mice, reporting that treated animals show reduced accumulation of neutrophils, CD4+ cells, and B lymphocytes compared to untreated mice, suggesting a role for PADs in leukocyte trafficking into the brain in AD mice. In conclusion, this PhD project demonstrated that PAD2 and PAD4 are key elements controlling leukocyte adhesion and that PAD-dependent citrullination is required for integrin-mediated adhesion under physiological and pathological conditions. Moreover, we reported that PADs are involved in disease pathogenesis in 3xTg-AD mice and that therapeutic blockade of PADs ameliorates cognition and reduces neuropathology, suggesting that PAD inhibitors may offer a novel therapeutic strategy for AD

Downconversion of Phonons to Suppress Correlated Errors in Superconducting Qubit Arrays

Quantum computers have the potential to solve critical problems that are intractable on conventional processors, with applications in a wide range of areas. The operation of a fault-tolerant quantum processor requires the use of quantum error correction, which involves encoding logical qubits across a large array of physical qubits. One promising system for implementing physical qubits is based on superconducting circuits, such as the transmon. For superconducting qubits, recent research have demonstrated that one source of decoherence comes from high-energy particles, such as gamma rays from background radioactivity and cosmic ray muons. When these particles hit the device substrate, they produce a burst of energetic phonons that travel throughout the chip. Upon hitting the device layer, these phonons generate dissipative excitations, which are quasiparticles, in the superconducting films that make up the qubit, thus causing an error in the qubit. Because the phonons from a single particle impact spread throughout the chip, a single impact event can cause correlated errors across the qubit array, which cannot be mitigated by conventional quantum error correction. In this thesis, we demonstrate a scheme to downconvert pair-breaking phonon energy by fabricating normal metal reservoirs on the back side of our qubit chip. We utilize voltage-biased Josephson junctions around the perimeter of our qubit chip to inject pair-breaking phonons into the substrate, allowing us to quantify our phonon downconversion efficiency. We investigate two devices, one with and one without normal metal reservoirs, that are measured in the same low-temperature environment. For the device with back-side metallization, we observe a reduction in the flux of injected pair-breaking phonons reaching the qubit by more than an order of magnitude. We also measured the quasiparticle charge parity switching rate on multiple qubits in the array, and observed a reduction in the two-fold and three-fold correlated switching rates by two orders of magnitude for the device with the normal metal reservoirs. This work thus provides a practical phonon downconversion technique that suppresses two-fold correlated errors in qubit arrays below the threshold required for running quantum error correction in the presence of background radioactivity

Towards a 'COOPING' Model for the Investigation of Gamers' Online Conversations in English

This paper proposes a cognitive-functional investigation of gamers’ uses of English in online communication, in order to enquire into the possibility of introducing a model that could be called COOPING (‘COOperation Principles between INternet Gamers’). COOPING was devised at the University of Salento, and it was conceived as a further development of both Grice’s maxims and Guido’s principles describing English lingua-franca uses in intercultural exchanges. The main research hypothesis is that the interactants’ awareness of the need to cooperate to reach shared targets prompts them to select a common linguistic means, which is usually a variation of English, when different linguacultural backgrounds come into contact. This paper will detail the four phases of COOPING—Evaluation, Acknowledgment, Negotiation, and Manner—which are expected to reflect the steps that players follow when they intend to cooperate in these virtual communities. Through an analysis of the selected corpus of conversations, this study will illustrate that gamers: (phases 1 and 2 of the Model) examine and evaluate the interlocutors’ behavior in order to assess their cooperative attitude; (phase 3) decide to select English when community members come from different linguistic and cultural backgrounds; and (phase 4) generate conversation turns that are characterized by specific features, from authentication, to meaning negotiation, to creative and critical modifications to the standard norms, trying to pursue reciprocal understanding and communication

Exact multiplicity of positive solutions in semipositone problems with concave-convex type nonlinearities

We study the existence, multiplicity, and stability of positive solutions to: \eqalign{- u''(x) &= \lambda f(u(x)) \ \text{for} \ x \in (-1, 1), \lambda > 0, \cr u(-1)&= 0\ = u(1) ,} where $f : [0, \infty) \to \Bbb R$ is semipositone ($f(0) 0$, we obtain the exact number of positive solutions as a function of $f(t)/t$ and establish how the positive solution curves to the above problem change. Also, we give examples where our results apply. This work extends the work in [1] by giving a complete classification of positive solutions for concave-convex type nonlinearities