The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Michael D Rugg - One of the best experts on this subject based on the ideXlab platform.
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overlap between the neural correlates of cued recall and source memory evidence for a generic recollection network
Journal of Cognitive Neuroscience, 2012Co-Authors: Hiroki R Hayama, Kaia L Vilberg, Michael D RuggAbstract:Recall of a studied Item and retrieval of its encoding context (source memory) both depend on recollection of qualitative information about the Study episode. This Study investigated whether recall and source memory engage overlapping neural regions. Participants (n = 18) studied a series of words, which were presented either to the left or right of fixation. fMRI data were collected during a subsequent test phase in which three-letter word-stems were presented, two thirds of which could be completed by a Study Item. Instructions were to use each stem as a cue to recall a studied word and, when recall was successful, to indicate the word's Study location. When recall failed, the stem was to be completed with the first word to come to mind. Relative to stems for which recall failed, word-stems eliciting successful recall were associated with enhanced activity in a variety of cortical regions, including bilateral parietal, posterior midline, and parahippocampal cortex. Activity in these regions was enhanced when recall was accompanied by successful rather than unsuccessful source retrieval. It is proposed that the regions form part of a "recollection network" in which activity is graded according to the amount of information retrieved about a Study episode.
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effects of divided attention on fmri correlates of memory encoding
Journal of Cognitive Neuroscience, 2005Co-Authors: Melina R Uncaphe, Michael D RuggAbstract:Performing a secondary task concurrently with a Study task has a detrimental effect on later memory for studied Items. To investigate the mechanisms underlying this effect, the processing resources available for an incidental encoding task were varied by manipulating secondary task difficulty. fMRI data were acquired as volunteers (n = 16) made animacy decisions to visually presented Study words while concurrently performing either an easy or a hard auditory monitoring task. "Subsequent memory effects"—greater activity at Study for words later remembered versus words later forgotten—were identified in the left ventral inferior frontal gyrus and the left anterior hippocampus. These effects did not vary according to whether the encoding task was performed concurrently with the easy or the hard secondary task. However, as secondary task difficulty increased, Study-Item activity declined and auditory-Item activity increased in dorsolateral prefrontal and superior parietal regions that have been implicated in the support of executive and control functions. The findings suggest that dividing attention during encoding influences the probability of engaging the encoding operations that support later episodic memory, but does not alter the nature of the operations themselves. The findings further suggest that the probability of engaging these encoding operations depends on the level of general processing resources engaged in service of the Study task.
Mohamed Kamoun - One of the best experts on this subject based on the ideXlab platform.
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preliminary results on 3d channel modeling from theory to standardization
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Abla Kammoun, Hajer Khanfir, Merouane Debbah, Zwi Altman, Mohamed KamounAbstract:Three dimensional (3D) beamforming (also elevation beamforming) is now gaining interest among researchers in wireless communication. The reason can be attributed to its potential for enabling a variety of strategies such as sector or user specific elevation beamforming and cell-splitting. Since these techniques cannot be directly supported by current LTE releases, the 3GPP is now working on defining the required technical specifications. In particular, a large effort is currently being made to get accurate 3D channel models that support the elevation dimension. This step is necessary as it will evaluate the potential of 3D and full dimensional (FD) beamforming techniques to benefit from the richness of real channels. This work aims at presenting the on-going 3GPP Study Item “Study on 3D-channel model for elevation beamforming and FD-MIMO studies for LTE” and positioning it with respect to previous standardization works.
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Preliminary results on 3D channel modeling: From theory to standardization
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Abla Kammoun, Hajer Khanfir, Merouane Debbah, Zwi Altman, Mohamed KamounAbstract:Three dimensional beamforming (3D) (also elevation beamforming) is now gaining a growing interest among researchers in wireless communication. The reason can be attributed to its potential to enable a variety of strategies like sector or user specific elevation beamforming and cell-splitting. Since these techniques cannot be directly supported by current LTE releases, the 3GPP is now working on defining the required technical specifications. In particular, a large effort is currently made to get accurate 3D channel models that support the elevation dimension. This step is necessary as it will evaluate the potential of 3D and FD(Full Dimensional) beamforming techniques to benefit from the richness of real channels. This work aims at presenting the on-going 3GPP Study Item "Study on 3D-channel model for Elevation Beamforming and FD-MIMO studies for LTE", and positioning it with respect to previous standardization works.
Tommaso Foggi - One of the best experts on this subject based on the ideXlab platform.
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Architectures and Key Technical Challenges for 5G Systems Incorporating Satellites
IEEE Transactions on Vehicular Technology, 2019Co-Authors: Alessandro Guidotti, Alessandro Vanelli-coralli, Matteo Conti, Stefano Andrenacci, Symeon Chatzinotas, Nicola Maturo, Barry Evans, Adegbenga Awoseyila, Alessandro Ugolini, Tommaso FoggiAbstract:Satellite communication systems are a promising solution to extend and complement terrestrial networks in unserved or under-served areas, as reflected by recent commercial and standardization endeavors. In particular, 3GPP recently initiated a Study Item for new radio, i.e., 5G, non-terrestrial networks aimed at deploying satellite systems either as a stand-alone solution or as an integration to terrestrial networks in mobile broadband and machine-type communication scenarios. However, typical satellite channel impairments, as large path losses, delays, and Doppler shifts, pose severe challenges to the realization of a satellite-based NR network. In this paper, based on the architecture options currently being discussed in the standardization fora, we discuss and assess the impact of the satellite channel characteristics on the physical and medium access control layers, both in terms of transmitted waveforms and procedures for enhanced mobile broadband and narrowband-Internet of Things applications. The proposed analysis shows that the main technical challenges are related to the PHY/MAC procedures, in particular random access, timing advance, and hybrid automatic repeat request and depending on the considered service and architecture, different solutions are proposed.
Abla Kammoun - One of the best experts on this subject based on the ideXlab platform.
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preliminary results on 3d channel modeling from theory to standardization
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Abla Kammoun, Hajer Khanfir, Merouane Debbah, Zwi Altman, Mohamed KamounAbstract:Three dimensional (3D) beamforming (also elevation beamforming) is now gaining interest among researchers in wireless communication. The reason can be attributed to its potential for enabling a variety of strategies such as sector or user specific elevation beamforming and cell-splitting. Since these techniques cannot be directly supported by current LTE releases, the 3GPP is now working on defining the required technical specifications. In particular, a large effort is currently being made to get accurate 3D channel models that support the elevation dimension. This step is necessary as it will evaluate the potential of 3D and full dimensional (FD) beamforming techniques to benefit from the richness of real channels. This work aims at presenting the on-going 3GPP Study Item “Study on 3D-channel model for elevation beamforming and FD-MIMO studies for LTE” and positioning it with respect to previous standardization works.
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Preliminary results on 3D channel modeling: From theory to standardization
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Abla Kammoun, Hajer Khanfir, Merouane Debbah, Zwi Altman, Mohamed KamounAbstract:Three dimensional beamforming (3D) (also elevation beamforming) is now gaining a growing interest among researchers in wireless communication. The reason can be attributed to its potential to enable a variety of strategies like sector or user specific elevation beamforming and cell-splitting. Since these techniques cannot be directly supported by current LTE releases, the 3GPP is now working on defining the required technical specifications. In particular, a large effort is currently made to get accurate 3D channel models that support the elevation dimension. This step is necessary as it will evaluate the potential of 3D and FD(Full Dimensional) beamforming techniques to benefit from the richness of real channels. This work aims at presenting the on-going 3GPP Study Item "Study on 3D-channel model for Elevation Beamforming and FD-MIMO studies for LTE", and positioning it with respect to previous standardization works.
Brian Mustanski - One of the best experts on this subject based on the ideXlab platform.
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evaluating hiv knowledge questionnaires among men who have sex with men a multi Study Item response theory analysis
Archives of Sexual Behavior, 2018Co-Authors: Patrick Janulis, Michael E Newcomb, Patrick S Sullivan, Brian MustanskiAbstract:Knowledge about the transmission, prevention, and treatment of HIV remains a critical element in psychosocial models of HIV risk behavior and is commonly used as an outcome in HIV prevention interventions. However, most HIV knowledge questions have not undergone rigorous psychometric testing such as using Item response theory. The current Study used data from six studies of men who have sex with men (MSM; n = 3565) to (1) examine the Item properties of HIV knowledge questions, (2) test for differential Item functioning on commonly studied characteristics (i.e., age, race/ethnicity, and HIV risk behavior), (3) select Items with the optimal Item characteristics, and (4) leverage this combined dataset to examine the potential moderating effect of age on the relationship between condomless anal sex (CAS) and HIV knowledge. Findings indicated that existing questions tend to poorly differentiate those with higher levels of HIV knowledge, but Items were relatively robust across diverse individuals. Furthermore, age moderated the relationship between CAS and HIV knowledge with older MSM having the strongest association. These findings suggest that additional Items are required in order to capture a more nuanced understanding of HIV knowledge and that the association between CAS and HIV knowledge may vary by age.
