4 research outputs found

    Measurement of the inclusive isolated-photon cross section in pp collisions at √s = 13 TeV using 36 fb−1 of ATLAS data

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    The differential cross section for isolated-photon production in pp collisions is measured at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 36.1 fb. The differential cross section is presented as a function of the photon transverse energy in different regions of photon pseudorapidity. The differential cross section as a function of the absolute value of the photon pseudorapidity is also presented in different regions of photon transverse energy. Next-to-leading-order QCD calculations from Jetphox and Sherpa as well as next-to-next-to-leading-order QCD calculations from Nnlojet are compared with the measurement, using several parameterisations of the proton parton distribution functions. The predictions provide a good description of the data within the experimental and theoretical uncertainties. [Figure not available: see fulltext.

    Measurement of jet fragmentation in Pb+Pb and pppp collisions at sNN=2.76\sqrt{{s_\mathrm{NN}}} = 2.76 TeV with the ATLAS detector at the LHC

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    Spectral Specificity of the Neural Dynamics Serving Attentional Orienting

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    Orienting attention toward task-relevant stimuli with spatial and temporal cues is common in experimental settings to investigate the neural dynamics serving attentional orienting. Spatial cues indicate the location in space a stimulus will appear, while temporal cues are predictive of the timing of stimulus onset. Previous functional neuroimaging studies have examined the divergence of neural networks involved in discrepant attentional orienting methods (i.e., spatial versus temporal). However, the rhythmic neural activity underlying temporal and spatial orienting is largely unstudied. The study described herein utilized magnetoencephalography (MEG) and an adapted Posner cueing task to evaluate the oscillatory dynamics serving spatial and temporal orienting. We found spectral dissociation where alpha (10-16 Hz) activity was critical for spatial orienting and theta (3-6 Hz) oscillations were pertinent to temporal orienting. Specifically, we observed decreases in alpha activity during spatial orienting in key attention areas and increases in theta power in primary visual areas. These findings suggest the rhythmic neural activity supporting attentional orienting are spectrally specific such that spatial orienting is served by alpha oscillatory dynamics and theta activity is necessitated for temporal orienting and provide further insight into the neural dynamics underlying attention

    Movement-related beta and gamma oscillations indicate parallels and disparities between Alzheimer's disease and HIV-associated neurocognitive disorder

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    People with HIV (PWH) often develop HIV-related neurological impairments known as HIV-associated neurocognitive disorder (HAND), but cognitive dysfunction in older PWH may also be due to age-related disorders such as Alzheimer's disease (AD). Discerning these two conditions is challenging since the specific neural characteristics are not well understood and limited studies have probed HAND and AD spectrum (ADS) directly. We examined the neural dynamics underlying motor processing during cognitive interference using magnetoencephalography (MEG) in 22 biomarker-confirmed patients on the ADS, 22 older participants diagnosed with HAND, and 30 healthy aging controls. MEG data were transformed into the time-frequency domain to examine movement-related oscillatory activity and the impact of cognitive interference on distinct stages of motor programming. Both cognitively impaired groups (ADS/HAND) performed significantly worse on the task (e.g., less accurate and slower reaction time) and exhibited reductions in frontal and cerebellar beta and parietal gamma activity relative to controls. Disease-specific aberrations were also detected such that those with HAND exhibited weaker gamma interference effects than those on the ADS in frontoparietal and motor areas. Additionally, temporally distinct beta interference effects were identified, with ADS participants exhibiting stronger beta interference activity in the temporal cortex during motor planning, along with weaker beta interference oscillations dispersed across frontoparietal and cerebellar cortices during movement execution relative to those with HAND. These results indicate both overlapping and distinct neurophysiological aberrations in those with ADS disorders or HAND in key motor and top-down cognitive processing regions during cognitive interference and provide new evidence for distinct neuropathology
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