1,548 research outputs found

    Some sharp Hardy inequalities on spherically symmetric domains

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    We prove some sharp Hardy inequalities for domains with a spherical symmetry. In particular, we prove an inequality for domains of the unit nn-dimensional sphere with a point singularity, and an inequality for functions defined on the half-space R+n+1\R_+^{n+1}} vanishing on the hyperplane {xn+1=0}\{x_{n+1}=0\}, with singularity along the xn+1x_{n+1}-axis. The proofs rely on a one-dimensional Hardy inequality involving a weight function related to the volume element on the sphere, as well as on symmetrization arguments. The one-dimensional inequality is derived in a general form.Comment: 15 page

    Automatic search of missing people in avalanches

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    One of the main source of danger for people practising activities in mountain environments is avalanches. In the early 70s has been commercialized the first model of avalanche beacon transceiver: a device, composed by a transmitter and a receiver, specialized to the purpose of finding people buried under the snow. Since 2013, project SHERPA is working to develop ground and aerial robots to support human in the search of missing people in avalanches. The aim of this dissertation is to provide a way to interface an avalanche beacon receiver (ARTVA) with the autopilot module mounted on a quad-copter drone, and to study and realize a software implementation of two automatic search algorithms, with the intention of speeding up search operations with drones. First we will focus on interfacing the ARTVA system with a quad-copter autopilot module, named Pixhawk. This module embed a software, named PX4, which runs on a real-time operating system (RTOS), and have several connection ports, among which there is the serial one that we will use for our purpose. Then we will analyse how to use the data coming from the ARTVA receiver to construct and implement the two search algorithms. The idea is to generate set-points, based on the information coming from the avalanche beacon receiver, and use them to feed the position controller which is implemented in the PX4 firmware. Finally, we will execute simulations, provide results, and investigate if a practical implementation is possible and what are the relative issues

    Rapid Serial Visual Presentation. Degradation of inferential reading comprehension as a function of speed

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    There is increasing interest in the readability of text presented on small digital screens. Designers have come up with novel text presentation methods, such as moving text from right to left, line-stepping, or showing successive text segments such as phrases or single words in a RSVP format. Comparative studies have indicated that RSVP is perhaps the best method of presenting text in a limited space. We tested the method using 209 participants divided into six groups. The groups included traditional reading, and RSVP reading at rates of 250, 300, 350, 400, and 450 wpm. No significant differences were found in comprehension for normal reading and RSVP reading at rates of 250, 300 and 350 wpm. However, higher rates produced significantly lower comprehension scores. It remains to be determined if, with additional practice and improved methods, good levels of reading comprehension at high rates can be achieved with RSV

    Novel technologies: study for application to fresh dairy sector

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    Ricotta is a potential growth medium for a wide range of microorganisms and it is an easily perishable food, characterized by a short shelf life (2-3 days), even under refrigerated conditions. Heat-based treatments can provoke microbial reduction, but alteration of the chemical and sensory profile can also occur. Therefore, in this Ph-D research alternative non-thermal technologies were tested on artisanal and industrial ricotta cheese to optimize parameters that promote quality preservation. The technologies tested were summarized in the figure 1 reported below (X-rays, Ultraviolet (UV-C) and Near Ultraviolet visible light (NUVL), Pulsed Light (PL) and Cold plasma). Specifically, artisanal and/or industrial ricotta were adopted for testing the effects of the above-mentioned techniques. In the first test artisanal and industrial ricotta samples were irradiated at 0.5, 2.0 and 3.0 kGy. At the two highest intensities (2.0 and 3.0 kGy), the artisanal product remained acceptable for more than 20 days, while the untreated samples became unacceptable after only 3 days of storage. The shelf life of the product irradiated at 0.5 kGy was limited to 14 days, due to the appearance of sensory defects. The industrial product irradiated at all X-rays intensities recorded a significant extension of the shelf life up to 84 days compared to the control which was discarded after 40 days due to sensory defects. As regard PL treatments at increasing fluence (1.3, 3.1, 7.5, 15.0 J/cm2) it was observed that PL at 1.3 and 3.1 J/cm2 allowed to delay microbial spoilage during storage, but higher fluences favored microbial growth and odor formation, possibly due to the surface nature of the PL technology. The analyses carried out on the product demonstrated that PL induced the formation of small protein particles, capable of interacting with lipids and carbohydrates and reorganizing into larger aggregates. Aggregation reduced protein solubility and occurred after exposure to hydrophobic protein groups. The photoreaction of proteins was confirmed by the formation of melanoidins and 8 carbonyls. Ricotta cheese artificially inoculated with Pseudomonas fluorescens was also tested by UV-C and NUVL. Results highlighted that the control samples became unacceptable after less than 5 days, while treated samples remained acceptable for more than 6 days. Finally, two different plasma-assisted approaches were assessed to extend the shelf life of artisanal ricotta cheese. In one test the plasma is applied indirectly, with plasma ignited in a controlled atmosphere (91% of N2 plus 9% of O2 supply gas) and the gaseous effluents (no plasma) directed to flow through small sterile tubes containing the cheese. In the other test product was directly exposed to the effects of the plasma. Treated and untreated samples were stored at 4 °C for a period of 8 days, during which microbiological, sensory and pH measurements were carried out. The results of the two approaches were similar: the concentrations of viable cells in the treated samples remained lower than those recorded in the control cheese, thus making the product more stable. From a sensorial point of view, the properties of ricotta in treated cheeses have been better preserved. Therefore, also cold plasma was effective in prolonging ricotta cheese shelf life

    Does the catechol-O-methyltransferase (COMT) Val158Met human polymorphism in influence procrastination?

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    Genetic studies are enlightening how the expression of several genes influences neuronal activity and all facets of human normal and abnormal behaviour. Among these, a growing body of information shows that a few key genes regulating activity of central neurotransmitters have specific roles in cognitive and/or emotional processes, as ‘procrastination’. We investigated the association of the 5-HTTLPR and COMT Val158Met polymorphisms with students’ procrastination in an academic writing task. Results: showed no relationship between procrastination and the 5-HTT polymorphism but they revealed an association with the COMT Val158Met one. Particularly, the presence of the Met158 allele was found to be significantly associated with the tendency to initiate and complete the assigned task. We hypothesize that the role of central monoamines and of dopamine already identified in impulsive behaviour, extends to procrastination. Since the 158Met allele provides neurons with significantly higher basal dopamine levels when compared to the 158Val allele, our observation suggests that under normal conditions the 158Met allele provides carriers with increased inhibitory control, resulting in an increased tendency to adhere to a planned schedule and therefore reducing procrastination. On the other hand, the Val158 allele may result more effective in increasing carriers’ performances under stress conditions, namely when the schedule deadline is approaching, and dopamine release is increased. This would result in a higher tendency to procrastinate. This hypothesis can readily be tested by applying the experimental approach here employed to various samples of subjects belonging to different categories and extending the analysis to other putative neuron-expressed gene

    Ocular-based automatic summarization of documents: is re-reading informative about the importance of a sentence?

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    Automatic document summarization (ADS) has been introduced as a viable solution for reducing the time and the effort needed to read the ever-increasing textual content that is disseminated. However, a successful universal ADS algorithm has not yet been developed. Also, despite progress in the field, many ADS techniques do not take into account the needs of different readers, providing a summary without internal consistency and the consequent need to re-read the original document. The present study was aimed at investigating the usefulness of using eye tracking for increasing the quality of ADS. The general idea was of that of finding ocular behavioural indicators that could be easily implemented in ADS algorithms. For instance, the time spent in re-reading a sentence might reflect the relative importance of that sentence, thus providing a hint for the selection of text contributing to the summary. We have tested this hypothesis by comparing metrics based on the analysis of eye movements of 30 readers with the highlights they made afterward. Results showed that the time spent reading a sentence was not significantly related to its subjective value, thus frustrating our attempt. Results also showed that the length of a sentence is an unavoidable confounding because longer sentences have both the highest probability of containing units of text judged as important, and receive more fixations and re-fixations

    A Comprehensive Review of Serious Games in Health Professions

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    Education of healthcare professionals is of primary importance for patient safety. In some health related professions, education and training have to be practiced during the entire working period and not only limited to school years. The use of new technology such as virtual reality and e-learning brings new possibilities with significant improvement in learning outcomes. Serious gaming describes a technology that can educate and train while entertaining users. This type of training can be very useful for health professions because it improves learning outcomes creating a learner oriented approach and providing a stealth mode of teaching. In some fields it represents an ideal instrument for continuous health professions education also in terms of costs because it is cheaper than traditional training methods that use cadavers or mannequins. In this paper we make a scoping review of serious games developed for health professions and health related fields in order to understand if they are useful tools for health related fields training. Many papers confirmed that serious gaming is a useful technology that improves learning and skills development for health professionals

    Non-Pharmacological Approaches in the Treatment of Dementia

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    Currently, a pharmacological disease-modifying treatment for dementia is not available, but different non-pharmacological approaches appear to be useful. In this chapter, we describe traditional treatments such as cognitive and emotion-oriented interventions, sensory and multi-sensory stimulation interventions and also potentially alternative interesting options such as behavioural therapy, animal-assisted therapy, home-adaptation therapy and assistive technologies to support patient with dementia. Many non-pharmacological treatments have reported benefits in multiple research studies, but there is a need for further Randomized controlled trials (RCTs) with an adequate sample size to improve the strength of evidence in order to apply these approaches

    Multi-agent quality of experience control

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    In the framework of the Future Internet, the aim of the Quality of Experience (QoE) Control functionalities is to track the personalized desired QoE level of the applications. The paper proposes to perform such a task by dynamically selecting the most appropriate Classes of Service (among the ones supported by the network), this selection being driven by a novel heuristic Multi-Agent Reinforcement Learning (MARL) algorithm. The paper shows that such an approach offers the opportunity to cope with some practical implementation problems: in particular, it allows to face the so-called “curse of dimensionality” of MARL algorithms, thus achieving satisfactory performance results even in the presence of several hundreds of Agents
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