1,823 research outputs found
Towards Coherent Neutrino Detection Using Low-Background Micropattern Gas Detectors
The detection of low energy neutrinos ( few tens of MeV) via coherent
nuclear scattering remains a holy grail of sorts in neutrino physics. This
uncontroversial mode of interaction is expected to profit from a sizeable
increase in cross section proportional to neutron number squared in the target
nucleus, an advantageous feature in view of the small probability of
interaction via all other channels in this energy region. A coherent neutrino
detector would open the door to many new applications, ranging from the study
of fundamental neutrino properties to true "neutrino technology".
Unfortunately, present-day radiation detectors of sufficiently large mass (
1 kg) are not sensitive to sub-keV nuclear recoils like those expected from
this channel. The advent of Micropattern Gas Detectors (MPGDs), new
technologies originally intended for use in High Energy Physics, may soon put
an end to this impasse. We present first tests of MPGDs fabricated with
radioclean materials and discuss the approach to assessing their sensitivity to
these faint signals. Applications are reviewed, in particular their use as a
safeguard against illegitimate operation of nuclear reactors. A first
industrial mass production of Gas Electron Multipliers (GEMs) is succinctly
described.Comment: Presented at the 2002 IEEE Nuclear Science Symposium and Medical
Imaging Conference, Norfolk VA, November 10-16. Submitted to IEEE Tran. Nucl.
Sci. Five pages, eight figure
Gifted Students and Advanced Mathematics
The extension to a wide population of secondary education in many countries seems to have led to a weakening of the mathematics curriculum. In response, many students have been classified as “gifted” so that they can access a stronger program. Apart from the difficulties that might arise in actually determining which students are gifted (is it always clear what the term means?), there are dangers inherent in programs that might be devised even for those that are truly talented.
Sometimes students are moved ahead to more advanced mathematics. Elementary students might be taught algebra or even subjects like trigonometry and vectors and secondary students taught calculus, differential equations and linear algebra.
It is my experience over thirty-five years of contact with bright students that acceleration to higher level mathematics is often not a good idea. In this paper, I will articulate some of the factors that have led me to this opinion and suggest alternatives. At the same time, one needs to deal with truly exceptional students in an appropriate way
Overcoming Barriers for the Wide-scale Adoption of Standardized Real-time Transit Information
In the last few years, a real-time counterpart to GTFS, GTFS-realtime [10], has begun to emerge, with agencies sharing their real-time data in this format. Previously, real-time transit information had only been shared in proprietary formats specific to each vendor or agency. GTFS-realtime offers the opportunity for application developers to create a mobile app that can function across a large number of cities and agencies, and for practitioners and researchers to be able to easily study and compare actual system performance across different transit systems using the same tools, without the overhead of manually transforming data into a consistent format. Having real-time transit data available in a common format is a key pillar for real-time multimodal information systems
Optical control of competing exchange interactions and coherent spin-charge coupling in two-orbital Mott insulators
In order to have a better understanding of ultrafast electrical control of
exchange interactions in multi-orbital systems, we study a two-orbital Hubbard
model at half filling under the action of a time-periodic electric field. Using
suitable projection operators and a generalized time-dependent canonical
transformation, we derive an effective Hamiltonian which describes two
different regimes. First, for a wide range of non-resonant frequencies, we find
a change of the bilinear Heisenberg exchange that is
analogous to the single-orbital case. Moreover we demonstrate that also the
additional biquadratic exchange interaction can be enhanced,
reduced and even change sign depending on the electric field. Second, for
special driving frequencies, we demonstrate a novel spin-charge coupling
phenomenon enabling coherent transfer between spin and charge degrees of
freedom of doubly ionized states. These results are confirmed by an exact
time-evolution of the full two-orbital Mott-Hubbard Hamiltonian.Comment: 3 pages, 6 figure
Webinar: Meeting & Exceeding Mobility User Expectations with Real-Time Transit Information
Every day transit riders ask the same question: when’s the next one coming? To answer this question, transit agencies are transitioning to providing real-time transit information through smartphones or displayed at transit stops.
The proliferation of transit planning and real time arrival tools that have hit the market over the past decade is staggering. Yet with transit ridership on the decline, agencies can’t afford to ignore the importance of providing accurate, real time information to their customers. Real-time transit information improves the reliability and efficiency of passenger travel, but barriers have prevented some transit agencies from adopting the GTFSrealtime v1.0 technology. A new NITC-funded study in May led by Sean Barbeau of the University of South Florida seeks to remove some of these barriers to make real-time transit info a universal amenity. As a public agency partner, moovel focuses on delivering simple, frictionless and accurate information through mobile applications. From mobile ticketing to multi/intermodal trip planning, booking and payment, moovel’s mobile apps take a customer-first approach to enhance the customer experience through an intuitive mobile solution.
This webinar will discuss the lessons learned from using GTFS and GTFS-realtime data in real-world applications and how these experiences lead to the development of the GTFS Best Practices (http://gtfs.org/best-practices/), GTFS-realtime v2.0 (https://developers.google.com/transit/gtfs-realtime/), and the open-source GTFS-realtime Validator tool (https://github.com/CUTR-at-USF/gtfs-realtime-validator). These new tools and standards will help reduce the time needed to develop, test, deploy, and maintain GTFS and GTFS-realtime feeds, which will in turn lead to better quality real-time information for transit riders and better operational and analytics information for transit agencies going forward. The presentation will also discuss the challenges and experiences faced by moovel as a vendor in working with agency data to meet modern, customer expectations in delivering accurate, real-time transportation data. KEY LEARNING OUTCOMES Understanding of how customer expectations shape the delivery of information/data Understanding of how transit agencies and their vendors can follow GTFS Best Practices and use the new GTFS-realtime v2.0 specification when implementing and maintaining data feeds, including putting in RFP requirements Challenges of working with multiple transportation providers to provide accurate real-time information Lessons learned from numerous focus groups and feedback studies Learn how to run the GTFS-realtime Validator tool on data regularly to maintain high-quality feeds Where the future of smart apps will take us and how we need to prepare for ithttps://pdxscholar.library.pdx.edu/trec_webinar/1032/thumbnail.jp
G-Sense: a scalable architecture for global sensing and monitoring
The pervasiveness of cellular phones combined with Internet connectivity, GPS embedded chips, location information, and integrated sensors provide an excellent platform to collect data about the individual and its surrounding environment. As a result, new applications have recently appeared to address large-scale societal problems as well as improve the quality of life of the individual. However, these new applications, recently called location-based services, participatory sensing, and human-centric sensing, bring many new challenges, one of them being the management of the huge amount of traffic (data) they generate. This article presents G-Sense, for Global-Sense, an architecture that integrates mobile and static wireless sensor networks in support of location-based services, participatory sensing, and human-centric sensing applications. G-Sense includes specific mechanisms to control the amount of data generated by these applications while meeting the application requirements. Furthermore, it creates a network of servers organized in a peer-to-peer architecture to address scalability and reliability issues. An example prototype application is presented along with some basic results and open research issues
Visual analytics for the interpretation of fluency tests during Alzheimer evaluation
International audienceA possible way to evaluate the progress of Alzheimer disease is to conduct the Isaac set test [13, 14]. In this activity, patients are asked to cite the largest possible number of city names within a minute. Since the city names are handwritten very quickly by a medical practitioner some cities are abbreviated or poorly written. In order to analyze such data, medical practitioners need to digitize the notes first and clean the dataset. Because these tasks are intricate and error prone we propose a novel set of tools, involving interactive visualization techniques, to help medical practitioners in the digitization and data-cleaning process. This system will be tested as part of an ongoing longitudinal study involving 9500 patients
Large-Mass Ultra-Low Noise Germanium Detectors: Performance and Applications in Neutrino and Astroparticle Physics
A new type of radiation detector, a p-type modified electrode germanium
diode, is presented. The prototype displays, for the first time, a combination
of features (mass, energy threshold and background expectation) required for a
measurement of coherent neutrino-nucleus scattering in a nuclear reactor
experiment. The device hybridizes the mass and energy resolution of a
conventional HPGe coaxial gamma spectrometer with the low electronic noise and
threshold of a small x-ray semiconductor detector, also displaying an intrinsic
ability to distinguish multiple from single-site particle interactions. The
present performance of the prototype and possible further improvements are
discussed, as well as other applications for this new type of device in
neutrino and astroparticle physics (double-beta decay, neutrino magnetic moment
and WIMP searches).Comment: submitted to Phys. Rev.
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