1,720,975 research outputs found
High-resolution optical spectroscopy of europium nitrate hexahydrate crystals
Get PDFWe report the optical study of europium nitrate hexahydrate crystals Eu(NO3)⋅3 6H2O and their deuterated version Eu(NO3)⋅3 6D2O conducted at 50 mK. The crystals show sub-GHz inhomogeneous linewidths for the F07↔5D0 transition and optical coherence times up to 136 μs for the non-deuterated crystal and 750 μs for the deuterated one. In addition, using the spectral hole burning technique, the hyperfine splittings in the absence of an external field have been estimated for the ground and optical levels. These results suggest that rare-earth nitrate crystals could represent a promising class of materials for quantum information applications as well as for fundamental physics experiments requiring narrow optical transitions and good coherence properties
SensCon: Embedding Physiological Sensing into Virtual Reality Controllers
No full textVirtual reality experiences increasingly use physiological data for virtual environment adaptations to evaluate user experience and immersion. Previous research required complex medical-grade equipment to collect physiological data, limiting real-world applicability. To overcome this, we present SensCon for skin conductance and heart rate data acquisition. To identify the optimal sensor location in the controller, we conducted a first study investigating users' controller grasp behavior. In a second study, we evaluated the performance of SensCon against medical-grade devices in six scenarios regarding user experience and signal quality. Users subjectively preferred SensCon in terms of usability and user experience. Moreover, the signal quality evaluation showed satisfactory accuracy across static, dynamic, and cognitive scenarios. Therefore, SensCon reduces the complexity of capturing and adapting the environment via real-time physiological data. By open-sourcing SensCon, we enable researchers and practitioners to adapt their virtual reality environment effortlessly. Finally, we discuss possible use cases for virtual reality-embedded physiological sensing
Infrared and visible scintillation of Ho3+-doped YAG and YLF crystals
Get PDFIn our effort to develop a new kind of detector for low-energy, low-rate energy deposition events we have investigated the cathodo- and radioluminescence of Ho:YAG and Ho:YLF single crystals in an extended wavelength range from 200 nm to 2200 nm. The emission spectra of both crystals show a much more intense emission in the infrared range than in the visible one. We estimate an infrared light yield of several tens of photons/keV when exciting the crystals with X-rays of energy ≈ 30 keV. The main reason of this high value is due to the Ho3+ ions energy levels scheme that allows efficient cross relaxation processes to occur even at low dopant concentration
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Theta and alpha oscillations as signatures of internal and external attention to delayed intentions: A magnetoencephalography (MEG) study
Get PDFBackground: Remembering to execute delayed intentions (i.e., prospective memory, PM) entails the allocation of internal and external attention. These processes are crucial for rehearsing PM intentions in memory and for monitoring the presence of the PM cue in the environment, respectively. Aim: The study took advantage of the excellent spatial and temporal resolution of magnetoencephalography (MEG) to delineate the neural mechanisms of the memory and monitoring processes underlying PM. Method: The spatio-temporal dynamic of theta and alpha oscillations were explored in 21 participants in two PM tasks compared to a baseline condition (i.e., a lexical decision task with no PM instruction). The PM tasks varied for the load of internally-directed attention (Retrospective-load task) vs externally-directed attention (Monitoring-load task). Results: Increase in theta activity was observed in the Retrospective-load task, and was particularly expressed in the regions of the Default Mode Network, such as in medial temporal regions, precuneus, posterior cingulate cortex and medial prefrontal cortex. Alpha decrease was the most relevant feature of the Monitoring-load task, and it was expressed over bilateral occipital, occipito-parietal and fronto-temporal regions, as well as over left dorsal fronto-parietal regions. Conclusions: Theta and alpha oscillations are strictly associated with the direction of attention during the PM tasks. In particular, theta increase is linked to internal attention necessary for maintaining the intention active in working memory, whereas alpha decrease supports the external attention for detecting the PM cue in the environment
X-ray detection by direct modulation of losses in a laser cavity
Get PDFIn this work, we experimentally explore the possibility to realize a sensor whose basic building block is a laser cavity that hosts a target crystal for the incident ionizing radiation. Two possible detection mechanisms are considered: a process of coherent scintillation related to the rapid decay via stimulated emission of the excited atomic or molecular levels of the target material and the activation of states that absorb intracavity photons. We use a solid-state laser to study the dynamic response of our prototype sensor and the related intrinsic limitations and demonstrate capability to detect x-ray energy down to 10 GeV
GaAs as a Bright Cryogenic Scintillator for the Detection of Low-Energy Electron Recoils from MeV/c2 Dark Matter
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