12,760 research outputs found

    Time and Geometric Quantization

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    In this paper we briefly review the functional version of the Koopman-von Neumann operatorial approach to classical mechanics. We then show that its quantization can be achieved by freezing to zero two Grassmannian partners of time. This method of quantization presents many similarities with the one known as Geometric Quantization.Comment: Talk given by EG at "Spacetime and Fundamental Interactions: Quantum Aspects. A conference to honour A.P.Balachandran's 65th birthday

    On Koopman-von Neumann Waves II

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    In this paper we continue the study, started in [1], of the operatorial formulation of classical mechanics given by Koopman and von Neumann (KvN) in the Thirties. In particular we show that the introduction of the KvN Hilbert space of complex and square integrable "wave functions" requires an enlargement of the set of the observables of ordinary classical mechanics. The possible role and the meaning of these extra observables is briefly indicated in this work. We also analyze the similarities and differences between non selective measurements and two-slit experiments in classical and quantum mechanics.Comment: 18+1 pages, 1 figure, misprints fixe

    Endothelial Dysfunction in Systemic Lupus Erythematosus: Pathogenesis, Assessment and Therapeutic Opportunities.

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    BACKGROUND: Systemic Lupus Erythematosus (SLE) is characterised by increased mortality secondary to Cardiovascular Diseases (CVD). Despite being common in SLE, traditional cardiovascular risk factors cannot entirely justify such increase in CVD-associated mortality. The endothelium is a key regulator of the vascular homeostasis; lupus-associated persistent systemic inflammation may impair endothelium functionality, thus initiating a cascade of events that, in concert with traditional CVD-risk factors, leads to atherosclerosis development and progression. Numerous methods have been used for the in vivo assessment of the endothelial function; among all, Flow- Mediated Dilatation (FMD) has been widely validated in clinical trials. Quantification of the endothelial dysfunction by FMD has been confirmed to be an early predictor of CVD in multiple studies involving both non-CVD and CVD-population and it may therefore represent a likewise efficient biomarker of CVD in SLE. METHODS: Research and online content related to endothelial function in SLE is reviewed in this article with special attention to the pathophysiology and therapeutic opportunities. RESULTS: To date, the vast majority of the available data, albeit not all, shows that endotheliumdependent FMD values are lower in SLE patients compared to healthy subjects; further studies, however, will be required in order to confirm the usefulness of the endothelial dysfunction quantification as CVD-predictor in the specific clinical setting of lupus. Notably, FMD variations can also be a sensitive marker for assessing specific therapeutic strategies ability of improving endothelial function in SLE patients. CONCLUSION: Endothelial function appears to be affected by SLE potentially contributing to the increased cardiovascular risk observed in SLE patients

    Chiral Anomalies via Classical and Quantum Functional Methods

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    In the quantum path integral formulation of a field theory model an anomaly arises when the functional measure is not invariant under a symmetry transformation of the Lagrangian. In this paper, generalizing previous work done on the point particle, we show that even at the classical level we can give a path integral formulation for any field theory model. Since classical mechanics cannot be affected by anomalies, the measure of the classical path integral of a field theory must be invariant under the symmetry. The classical path integral measure contains the fields of the quantum one plus some extra auxiliary ones. So, at the classical level, there must be a sort of "cancellation" of the quantum anomaly between the original fields and the auxiliary ones. In this paper we prove in detail how this occurs for the chiral anomaly.Comment: 26 pages, Latex, misprint fixed, a dedication include

    Quantitative Analysis by 3D Graphics of Thoraco-Abdominal Surface Shape and Breathing Motion

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    Chest wall motion can provide information on respiratory muscles' action and on critical vital signs, like respiration and cardiac activity. The chest wall is a structure with three compartments that are independent to each other and can move paradoxically according to the pathophysiology of the disease. Opto-electronic plethysmography (OEP) allows for non-invasively 3D tracking of body movements. We aimed to extend the characteristics of OEP analysis to local analyses of thoraco-abdominal surface geometry and kinematics during respiration. Starting from the OEP output file, the 3D markers’ coordinates were combined with a triangulation matrix. A smoothing procedure (an automatic and iterative interpolation process to increase the number of vertices from 93 to 548) was applied to allow for precise local analysis of the thoraco-abdominal surface. A series of measurements can be performed to characterize the geometry of the trunk and its three compartments, in terms of volumes, height, diameters, perimeters, and area. Some shape factors, such as surface-to-volume ratio or height-to-perimeter ratio, can be also computed. It was also possible to build the vector field associated with the breathing motion of all the vertices, in terms of magnitude and motion direction. The vector field data were analyzed and displayed through two graphic tools: a 3D heatmap, in which the magnitude of motion was associated to different colors, and a 3D arrow plot, that allowed us to visualize both the magnitude and the direction of motion with color-coded arrows. The methods were applied to 10 healthy subjects (5 females) and also applied to two cases: a pregnant woman at each trimester of gestation and a patient before and after a demolition thoracic surgery. The results proved to be coherent with the physiology of healthy subjects and the physiopathology of the cases. We developed a new non-invasive method for respiratory analysis that allowed for the creation of realistic 3D models of the local and global trunk surface during respiration. The proposed representation constituted a very intuitive method to visualize and compare thoraco-abdominal surface movements within and between subjects, therefore enforcing the potential clinical translational value of the method

    The effectiveness of intra-articular injectionc of Hyalubrix combined with exercise therapy in the tratment of hip osteoarthritis

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    Purpose. Osteoarthritis (OA) is the most common joint disorder in the elderly, causing significant pain which negatively affects mobility and quality ol liie. The aim of the study was to assess the effectiveness of ultrasound \ucdmage-guided intra-articular injections of Hyalubrix@ combined with exercise therapy in the treatment of hip osteoarthritis. Methods. This was a single site, prosp\ue8ctive, open-fabel, Investigator-initiated study. Forty patients rilere enrolled and received three ultrasound image.guided injections of Hyalubrix@, 45 days apart, combined with three sessions a week of phys\uedcal therapy (proprioceptive rehabilitation of the lower limbs; gait training; balance training) up to a total of 30 sessions (10 weeks), starting from one week after the first injection. Results. The primary obiective was to achieve a lasting reduction in OA symptoms related to pain during activity. During the course of the study the pain perceived by the patient during activity dropped from a mean value of 6.94 cm to a mean value of 1.46 cm and showed a statistically significant decrease from visit 1 compared to baseline (p < 0.05) which was confirmed at all the subsequent time points. Significant improvements were also observed in the evaluation of the secondary objectives: hip disability; OA-related pain at rest; daily functioning and NSAIDs intake. Conclusions. Results from this study including 40 patients for a total of 65 treated hips demonstrate a significant improvement in OA-related pain, hip disability, and patient's daily functioning as well as a reduction in NSAIDS intake. Patients suffering from hip OA s\ue8em to benefil from the treatment wiih Hyalubrix@ injections plus exercise therapy

    Eco-friendly gas mixtures for Resistive Plate Chambers based on Tetrafluoropropene and Helium

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    Due to the recent restrictions deriving from the application of the Kyoto protocol, the main components of the gas mixtures presently used in the Resistive Plate Chambers systems of the LHC experiments will be most probably phased out of production in the coming years. Identifying possible replacements with the adequate characteristics requires an intense R&D, which was recently started, also in collaborations across the various experiments. Possible candidates have been proposed and are thoroughly investigated. Some tests on one of the most promising candidate - HFO-1234ze, an allotropic form of tetrafluoropropane- have already been reported. Here an innovative approach, based on the use of Helium, to solve the problems related to the too elevate operating voltage of HFO-1234ze based gas mixtures, is discussed and the relative first results are shown.Comment: 9 pages, 6 figures, 1 tabl

    Hybrid Model For Word Prediction Using Naive Bayes and Latent Information

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    Historically, the Natural Language Processing area has been given too much attention by many researchers. One of the main motivation beyond this interest is related to the word prediction problem, which states that given a set words in a sentence, one can recommend the next word. In literature, this problem is solved by methods based on syntactic or semantic analysis. Solely, each of these analysis cannot achieve practical results for end-user applications. For instance, the Latent Semantic Analysis can handle semantic features of text, but cannot suggest words considering syntactical rules. On the other hand, there are models that treat both methods together and achieve state-of-the-art results, e.g. Deep Learning. These models can demand high computational effort, which can make the model infeasible for certain types of applications. With the advance of the technology and mathematical models, it is possible to develop faster systems with more accuracy. This work proposes a hybrid word suggestion model, based on Naive Bayes and Latent Semantic Analysis, considering neighbouring words around unfilled gaps. Results show that this model could achieve 44.2% of accuracy in the MSR Sentence Completion Challenge

    R&D results on a CsI-TTGEM based photodetector

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    The very high momentum particle identification detector proposed for the ALICE upgrade is a focusing RICH using a C4F10 gaseous radiator. For the detection of Cherenkov photons, one of the options currently under investigation is to use a CsI coated Triple-Thick-GEM (CsI-TTGEM) with metallic or resistive electrodes. We will present results from the laboratory studies as well as preliminary results of beam tests of a RICH detector prototype consisting of a CaF2 radiator coupled to a 10x10 cm2 CsI-TTGEM equipped with a pad readout and GASSIPLEX-based front-end electronics. With such a prototype the detection of Cherenkov photons simultaneously with minimum ionizing particles has been achieved for the first time in a stable operation mode
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