Particle acceleration and radiation friction effects in the filamentation instability of pair plasmas

The evolution of the filamentation instability produced by two counter-streaming pair plasmas is studied with particle-in-cell (PIC) simulations in both one (1D) and two (2D) spatial dimensions. Radiation friction effects on particles are taken into account. After an exponential growth of both the magnetic field and the current density, a nonlinear quasi-stationary phase sets up characterized by filaments of opposite currents. During the nonlinear stage, a strong broadening of the particle energy spectrum occurs accompanied by the formation of a peak at twice their initial energy. A simple theory of the peak formation is presented. The presence of radiative losses does not change the dynamics of the instability but affects the structure of the particle spectra.Comment: 8 pages, 8 figures, submitted to MNRA

Artificial Neural Networks in archaeology

Artificial neural networks are adaptive models that can be used for classification and pattern recognition purposes. ANNs do not differ from standard statistical models. The main difference between ANNs and traditional statistical models is their construction and definition process. In fact ANNs are adaptive in the sense that they can learn. Landscape Archaeology is a research area where the application of ANNs can be very useful. ANNs can be used for Landscape pattern recognition and Settlement systems modeling. This paper illustrate some aspects of the development of new tools and the application of ANNs in a raster GIS environment for archaeological predictive modeling purposes

A framework for fault detection and diagnostics of articulated collaborative robots based on hybrid series modelling of Artificial Intelligence algorithms

Smart factories build on cyber-physical systems as one of the most promising technological concepts. Within smart factories, condition-based and predictive maintenance are key solutions to improve competitiveness by reducing downtimes and increasing the overall equipment effectiveness. Besides, the growing interest towards operation flexibility has pushed companies to introduce novel solutions on the shop floor, leading to install cobots for advanced human-machine collaboration. Despite their reliability, also cobots are subjected to degradation and functional failures may influence their operation, leading to anomalous trajectories. In this context, the literature shows gaps in what concerns a systematic adoption of condition-based and predictive maintenance to monitor and predict the health state of cobots to finally assure their expected performance. This work proposes an approach that leverages on a framework for fault detection and diagnostics of cobots inspired by the Prognostics and Health Management process as a guideline. The goal is to habilitate first-level maintenance, which aims at informing the operator about anomalous trajectories. The framework is enabled by a modular structure consisting of hybrid series modelling of unsupervised Artificial Intelligence algorithms, and it is assessed by inducing three functional failures in a 7-axis collaborative robot used for pick and place operations. The framework demonstrates the capability to accommodate and handle different trajectories while notifying the unhealthy state of cobots. Thanks to its structure, the framework is open to testing and comparing more algorithms in future research to identify the best-in-class in each of the proposed steps given the operational context on the shop floor

The Importance of Nutrition in Hypertension

Arterial hypertension (AH) is considered to be one of the most relevant cardiovascular risk factors, and its wide prevalence in all age ranges makes it necessary to analyse all the possible causes and treatments. In this special issue, nutritional interventions are examined either as causes or as treatments of AH. [...]

Health, fitness, and life satisfaction in retired teachers

The purpose of this study was to describe the health, fitness, and life satisfaction of retired teachers in Thunder Bay. Forty retired teachers (24 women, 16 men) aged 55 to 70 years participated in the study. Fitness level, physical activity participation, and lifestyle habits were measured according to the protocol of The Canadian Physical Activity, Fitness, and Lifestyle Appraisal (CPAFLA), and compared to Estimated Health Benefit Zones. Fitness level was also compared to norms from the 1981 Canada Fitness Survey (CFS). Over 50% of the sample scored Good or higher on all fitness measures, and on measures of physical activity participation and lifestyle habits, over 90% scored in this range. Comparisons to the CFS revealed average fitness levels, not markedly different from the general Canadian population. Levels of high density lipoproteins (HDL), low density lipoproteins (LDL), and triglycerides, as well as the ratio of total cholesterol to HDL were in a range designated as healthy or desirable for at least 50% of the sample. Self-report measures indicated a high level of satisfaction with retirement life, and extremely healthy lifestyle behaviours. Both perceived health and life satisfaction were significantly correlated with aerobic fitness, indicating possible benefits of maintaining a physically active lifestyle during retirement. Retired teachers were found to be in good physical health, possess exceptionally healthy behaviours with respect to lifestyle and physical activity participation, and be extremely satisfied with retirement life

Simulation-supported framework for job shop scheduling with genetic algorithm

The Job Shop Scheduling Problem (JSSP) is recognized to be one of the most difficult scheduling problems, being NP-complete. During years, many different solving techniques were developed: some techniques are focused on the development of optimization algorithms, whilst others are based on simulation models. Since the 80s, it was recognized that a combination of the two could be of big advantage, matching advantages from both sides. However, this research stream has not been followed to a great extent. The goal of this study is to propose a novel scheduling tool able to match these two really different techniques in one common framework in order to fill this gap in literature. The base of the framework is composed by a genetic algorithm (GA) and a simulation model is introduced into the evaluation of the fitness function, due to the inability of GAs in taking into account the real performances of a production system. An additional purpose of this research is to improve the collaboration between academic and industrial worlds on the topic, through an application of the novel scheduling framework to an industrial case. The implementation to the industrial case also suggested an improvement of the tool: The introduction of the stochasticity into the proposed scheduling framework in order to consider the variable nature of the production systems

Surface Oscillations in Overdense Plasmas Irradiated by Ultrashort Laser Pulses

The generation of electron surface oscillations in overdense plasmas irradiated at normal incidence by an intense laser pulse is investigated. Two-dimensional (2D) particle-in-cell simulations show a transition from a planar, electrostatic oscillation at $2\omega$, with $\omega$ the laser frequency, to a 2D electromagnetic oscillation at frequency $\omega$ and wavevector $k>\omega/c$. A new electron parametric instability, involving the decay of a 1D electrostatic oscillation into two surface waves, is introduced to explain the basic features of the 2D oscillations. This effect leads to the rippling of the plasma surface within a few laser cycles, and is likely to have a strong impact on laser interaction with solid targets.Comment: 9 pages (LaTeX, Revtex4), 4 GIF color figures, accepted for publication in Phys. Rev. Let

Pancreatic solid pseudopapillary neoplasm in male patients: systematic review with three new cases

Pancreatic solid pseudopapillary neoplasm (pSPN) is a rare exocrine neoplasm, which generally occurs in young women. This study analyses the clinical characteristics of pSPN in male patients through a systematic review of the literature, adding three new cases from our institution. We reviewed our experience in Pspns, and we performed a systematic review of pSPN of all articles published in English in PubMed and SCOPUS from 1980. Using the final included articles, we evaluated clinic-pathological features, surgical treatment and prognosis of male patients affected by pSPN. From the literature review and our cases, we collected 246 male patients with a proven pSPN. Mean age was 34.3 (range 4\u201378) years, with 26.2% patients younger than 18\ua0years. Patients were asymptomatic in 35.9% of cases, despite a mean tumour size of 6.3\ua0cm. In 63.7% of cases, the pSPN was located in the body\u2013tail region. Distant metastases were reported at diagnosis in only 10 (4.1%) patients. A correct pre-operative diagnosis (including cytopathology) was provided in 53.6% of patients, with only 40 fine-needle aspiration/biopsy performed. Standard pancreatic resections represented 90.4% of surgical procedures. Beta-catenin and progesterone receptors were positive at immunostaining in 100% and 77.8% of cases, respectively. Fourteen (7.2%) patients relapsed after a mean disease-free survival of 43.1\ua0months. After a mean follow-up of 47 (range 4\u2013180) months, 89.5% of patients were alive and disease-free. Although rare, when dealing with a solid-cystic pancreatic mass, even in asymptomatic male patients, a pSPN should be considered as a possible diagnosis

Dynamics of charge-displacement channeling in intense laser-plasma interactions

The dynamics of transient electric fields generated by the interaction of high intensity laser pulses with underdense plasmas has been studied experimentally with the proton projection imaging technique. The formation of a charged channel, the propagation of its front edge and the late electric field evolution have been characterised with high temporal and spatial resolution. Particle-in-cell simulations and an electrostatic, ponderomotive model reproduce the experimental features and trace them back to the ponderomotive expulsion of electrons and the subsequent ion acceleration.Comment: 5 figures, accepted for publication in New Journal of Physic