3,433 research outputs found
The legacy of the OPERA experiment on neutrino oscillations
The OPERA experiment has conclusively observed the appearance of tau neutrinos in the muon neutrino CNGS beam. High purity samples of νe, νµ and ντ charged current neutrino interactions, as well as neutral current interactions were isolated. Recent results obtained using the full dataset to test the three-flavor neutrino oscillation model are discussed. Constraints on the existence of a light sterile neutrino, derived using for the first time tau and electron neutrino appearance channels, are also presented. A significant fraction of the sterile neutrino parameter space allowed by LSND and MiniBooNE experiments is excluded at 90% C.L. In particular, the best-fit oscillation parameter values obtained by MiniBooNE are excluded at 3.3σ significance
Final results of the OPERA experiment on ντ appearance and the OPERA legacy
OPERA (Oscillation Project with Emulsion tRacking Apparatus) was a long-baseline experiment at the INFN Gran Sasso laboratory (LNGS) designed to search for νμ → ντ oscillations in appearance mode. It took data from 2008 to 2012 with the CNGS neutrino beam from CERN. In 2015, after the detection of five ντ candidates with a signal-to-background ratio of ∼ 10, the discovery of ντ appearance in the CNGS beam was announced with 5.1σ significance. After having reached the experiment main goal, the selection of ντ candidates has been extended by loosening the selection criteria and applying a multivariate approach for events identification, in order to improve the statistical uncertainty in the measurement of the oscillation parameters and of ντ properties. Future experiments that will take advantage of the improvements done by OPERA in the use of nuclear emulsions will also be described
Age-related effects on spatial memory across viewpoint changes relative to different reference frames
Remembering object positions across different views is a fundamental competence for acting and moving appropriately in a large-scale space. Behavioural and neurological changes in elderly subjects suggest that the spatial representations of the environment might decline compared to young participants. However, no data are available on the use of different reference frames within topographical space in aging. Here we investigated the use of allocentric and egocentric frames in aging, by asking young and older participants to encode the location of a target in a virtual room relative either to stable features of the room (allocentric environment-based frame), or to an unstable objects set (allocentric objects-based frame), or to the viewer's viewpoint (egocentric frame). After a viewpoint change of 0 (absent), 45 (small) or 135 (large), participants judged whether the target was in the same spatial position as before relative to one of the three frames. Results revealed a different susceptibility to viewpoint changes in older than young participants. Importantly, we detected a worst performance, in terms of reaction times, for older than young participants in the allocentric frames. The deficit was more marked for the environment-based frame, for which a lower sensitivity was revealed as well as a worst performance even when no viewpoint change occurred. Our data provide new evidence of a greater vulnerability of the allocentric, in particular environment-based, spatial coding with aging, in line with the retrogenesis theory according to which cognitive changes in aging reverse the sequence of acquisition in mental development
Directional dark matter search with nuclear emulsion
The NEWSdm experiment, based on nuclear emulsions, is proposed to measure the direction of WIMP-induced nuclear recoils. We discuss the potentiality, both in terms of exclusion limits and potential discovery, of a directional experiment based on the use of a solid target made by newly developed nuclear emulsions and read-out systems reaching sub-micrometric resolution
Noise radar technology as an interference prevention method
In some applications, such as automotive and marine/navigation, hundreds of radars may operate in a small environment (e.g., a road complex or a strait) and in an allocated frequency band with limited width. Therefore, a compatibility problem between different radars arises that is not easily solved by time, frequency, space, or polarization diversity. The advent of fast digital signal processing and signal generation techniques makes it possible to use waveform diversity to solve this problem that will be exacerbated in the next future. Ideal waveforms for the diversity are supplied by Noise Radar Technology (NRT), whose application is promising in some military applications as well as in the civilian applications considered in this paper. In addition to being orthogonal as much as possible, the random signals to be transmitted have to satisfy requirements concerning side lobe level and crest factor, calling for novel, original design and generation processes
Game Theoretic Target Assignment Strategies in Competitive Multi-Team Systems
The task of optimally assigning military ordinance to enemy targets, often termed the Weapon Target Assignment (WTA) problem, has become a major focus of modern military thought. Current formulations of this problem consider the enemy targets as either passive or entirely defensive. As a result, the assignment problem is solved purely as a one sided team optimization problem. In practice, however, especially in environments characterized by the presence of an intelligent adversary, this one sided optimization approach has very limited use. The presence of an adversary often necessitates incorporating its intended actions in the process of solving the weapons assignment problem. In this dissertation, we formulate the weapon target assignment problem in the presence of an intelligent adversary within the framework of game theory. We consider two teams of opposing units simultaneously targeting each other and examine several possible game theoretic solutions of this problem. An issue that arises when searching for any solution is the dimensionality of the search space which quickly becomes overwhelming even for simple problems with a small number of units on each side. To solve this scalability issue, we present a novel algorithm called Unit Level Team Resource Allocation (ULTRA), which is capable of generating approximate solutions by searching within appropriate subspaces of the search space. We evaluate the performance of this algorithm on several realistic simulation scenarios. We also show that this algorithm can be effectively implemented in real-time as an automatic target assigning controller in a dynamic multi-stage problem involving two teams with large number of units in conflict
Resting-state connectivity and functional specialization in human medial parieto-occipital cortex
According to recent models of visuo-spatial processing, the medial parieto-occipital cortex is a crucial node of the dorsal visual stream. Evidence from neurophysiological studies in monkeys has indicated that the parieto-occipital sulcus (POS) contains three functionally and cytoarchitectonically distinct areas: the visual area V6 in the fundus of the POS, and the visuo-motor areas V6Av and V6Ad in a progressively dorsal and anterior location with respect to V6. Besides different topographical organization, cytoarchitectonics, and functional properties, these three monkey areas can also be distinguished based on their patterns of cortico-cortical connections. Thanks to wide-field retinotopic mapping, areas V6 and V6Av have been also mapped in the human brain. Here, using a combined approach of resting-state functional connectivity and task-evoked activity by fMRI, we identified a new region in the anterior POS showing a pattern of functional properties and cortical connections that suggests a homology with the monkey area V6Ad. In addition, we observed distinct patterns of cortical connections associated with the human V6 and V6Av which are remarkably consistent with those showed by the anatomical tracing studies in the corresponding monkey areas. Consistent with recent models on visuo-spatial processing, our findings demonstrate a gradient of functional specialization and cortical connections within the human POS, with more posterior regions primarily dedicated to the analysis of visual attributes useful for spatial navigation and more anterior regions primarily dedicated to analyses of spatial information relevant for goal-directed action
Stochastic simulation techniques as related to innovation in communications-navigation-surveillance and air traffic management (CNS/ATM)
The design and operational tuning of the instruments and procedures employed in communications-navigation-surveillance (CNS) and air traffic management (ATM) often relies on stochastic simulation techniques. In this paper the application areas of simulation in the CNS/ATM context are reviewed together with the simulation methods that can help solve the main problems encountered, i.e. quick simulation techniques for the simulation of rare events, and the bootstrap technique for the evaluation of the accuracy of the results
W-band noise radar in short range applications
Noise Radar Technology (NRT) uses noise waveforms (continuous or pulsed) as a radar signal and correlation processing of the returns for their optimal reception. This paper is devoted to some possible applications of NRT in civil field, in particular to millimetre-wave radars, with comparison of the use of Noise W-band radar versus the more classical FM-CW or pulse compression solutions
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