Perceval: A Software Platform for Discrete Variable Photonic Quantum Computing

We introduce Perceval, an evolutive open-source software platform for simulating and interfacing with discrete variable photonic quantum computers, and describe its main features and components. Its Python front-end allows photonic circuits to be composed from basic photonic building blocks like photon sources, beam splitters, phase shifters and detectors. A variety of computational back-ends are available and optimised for different use-cases. These use state-of-the-art simulation techniques covering both weak simulation, or sampling, and strong simulation. We give examples of Perceval in action by reproducing a variety of photonic experiments and simulating photonic implementations of a range of quantum algorithms, from Grover's and Shor's to examples of quantum machine learning. Perceval is intended to be a useful toolkit both for experimentalists wishing to easily model, design, simulate, or optimise a discrete variable photonic experiment, and for theoreticians wishing to design algorithms and applications for discrete-variable photonic quantum computing platforms

The rapid spread of SARS-COV-2 Omicron variant in Italy reflected early through wastewater surveillance

The SARS-CoV-2 Omicron variant emerged in South Africa in November 2021, and has later been identified worldwide, raising serious concerns. A real-time RT-PCR assay was designed for the rapid screening of the Omicron variant, targeting characteristic mutations of the spike gene. The assay was used to test 737 sewage samples collected throughout Italy (19/21 Regions) between 11 November and 25 December 2021, with the aim of assessing the spread of the Omicron variant in the country. Positive samples were also tested with a real-time RT-PCR developed by the European Commission, Joint Research Centre (JRC), and through nested RT-PCR followed by Sanger sequencing. Overall, 115 samples tested positive for Omicron SARS-CoV-2 variant. The first occurrence was detected on 7 December, in Veneto, North Italy. Later on, the variant spread extremely fast in three weeks, with prevalence of positive wastewater samples rising from 1.0% (1/104 samples) in the week 5-11 December, to 17.5% (25/143 samples) in the week 12-18, to 65.9% (89/135 samples) in the week 19-25, in line with the increase in cases of infection with the Omicron variant observed during December in Italy. Similarly, the number of Regions/Autonomous Provinces in which the variant was detected increased from one in the first week, to 11 in the second, and to 17 in the last one. The presence of the Omicron variant was confirmed by the JRC real-time RT-PCR in 79.1% (91/115) of the positive samples, and by Sanger sequencing in 66% (64/97) of PCR amplicons. In conclusion, we designed an RT-qPCR assay capable to detect the Omicron variant, which can be successfully used for the purpose of wastewater-based epidemiology. We also described the history of the introduction and diffusion of the Omicron variant in the Italian population and territory, confirming the effectiveness of sewage monitoring as a powerful surveillance tool

The brain's dorsal route for speech represents word meaning: evidence from gesture.

The dual-route model of speech processing includes a dorsal stream that maps auditory to motor features at the sublexical level rather than at the lexico-semantic level. However, the literature on gesture is an invitation to revise this model because it suggests that the premotor cortex of the dorsal route is a major site of lexico-semantic interaction. Here we investigated lexico-semantic mapping using word-gesture pairs that were either congruent or incongruent. Using fMRI-adaptation in 28 subjects, we found that temporo-parietal and premotor activity during auditory processing of single action words was modulated by the prior audiovisual context in which the words had been repeated. The BOLD signal was suppressed following repetition of the auditory word alone, and further suppressed following repetition of the word accompanied by a congruent gesture (e.g. ["grasp" + grasping gesture]). Conversely, repetition suppression was not observed when the same action word was accompanied by an incongruent gesture (e.g. ["grasp" + sprinkle]). We propose a simple model to explain these results: auditory and visual information converge onto premotor cortex where it is represented in a comparable format to determine (in)congruence between speech and gesture. This ability of the dorsal route to detect audiovisual semantic (in)congruence suggests that its function is not restricted to the sublexical level

Functional parcellation of the lateral mesencephalus.

International audienceThe mesencephalic locomotor region (MLR), which includes the pedunculopontine nucleus (PPN) and the cuneiform nucleus (CN), has been recently identified as a key structure for locomotion and gait control in mammals. However, the function and the precise anatomy of the MLR remain unclear in humans. To study the lateral mesencephalus, we used fMRI in 15 right-handed healthy volunteers performing two tasks: imagine walking in a hallway and imagine an object moving along the same hallway. Both tasks were performed at two different speeds: normal and 30% faster. We identified two distinct networks of cortical activation: one involving motor/premotor cortices and the cerebellum for the walking task and the other involving posterior parietal and dorsolateral prefrontal cortices for the object moving task. In the lateral mesencephalus, we found that two different but anatomically connected parts of the MLR were activated during the fast condition of each task. The CN and the dorsal part of the PPN were activated during the fast imaginary walking task, whereas the ventral part of the PPN and the ventral part of the reticular formation were activated while subjects were imagining the object moving fast. Our data suggest that the lateral mesencephalus participates in different aspects of gait in humans, with the CN and dorsal PPN controlling motor aspects of locomotion and the ventral PPN being involved in integrating sensory information

Repetition× Congruence.

<p>SPM rendering of the contrast NR-R following SGC versus SGI. Areas colored in blue or green are likely to be located in Brodmann’s cytoarchitectonic area 6 or 44 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046108#pone.0046108-Eickhoff1" target="_blank">[37]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046108#pone.0046108-Eickhoff2" target="_blank">[38]</a>. The area colored in blue is most likely area 44, the area in green is most likely area 6. The 2 highest intensity peaks in the cluster were located in area 6 with a 100% probability. SGC: Congruent Speech and Gesture, SGI: Incongruent Speech and Gesture, NR: Non-Repeated, R: Repeated.</p

Neuronal model explaining activations and repetition effects associated with the presentation of an action word, and the modulation of theses effects by the audiovisual context.

<p>NR: Non-Repeated, R: Repeated, S: Speech (average of Si and Sc between which no difference was found), SGC: Congruent Speech and Gesture, SGI: Incongruent Speech and Gesture.</p

Initial phase.

<p>All effects were significant after correcting for multiple comparisons across the whole brain, either in terms of intensity or spatial extent. Coordinates are in the template space of the Montreal Neurological Institute (transformed from the symmetrical template space used for normalization). Sc: Speech  =  audio corresponding to SGC, SGC: Congruent Speech and Gesture, SGI: Incongruent Speech and Gesture.</p

Initial Phase.

<p>SPM renderings with one medial section to show SGI>SGC activation in the supplementary motor area. Maps were thresholded at p<0.05 corrected for multiple comparisons either in terms of height or spatial extent. The right precentral cluster in S>Rest, approaching significance, is also shown. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046108#pone-0046108-t001" target="_blank">Table 1</a> for details. S: Speech (average of Si and Sc between which no difference was found), SGC: Congruent Speech and Gesture, SGI: Incongruent Speech and Gesture.</p

Test phase.

<p>Effects in bold are corrected for multiple comparisons either in terms of intensity of spatial extent. Effects marked by a * were Family-Wise Error corrected for multiple comparisons in terms of intensity inside a mask corresponding to brain regions activated by auditory word processing. Coordinates are in the template space of the Montreal Neurological Institute (transformed from the symmetrical template space used for normalization). SGC: Congruent Speech and Gesture, Sc: audio corresponding to SGC, SGI: Incongruent Speech and Gesture, Si: audio corresponding to SGI, NR: Non-Repeated, R: Repeated.</p

Stimuli.

<p>Stillframes of video stimuli from the two audiovisual conditions where Speech and Gesture were either Congruent (SGC) or Incongruent (SGI). In the two corresponding speech-only conditions (respectively Sc and Si), videos were shown with a black mask macthing the background, so that subjets only perceived the audio from the video files.</p