Playable Environments: {V}ideo Manipulation in Space and Time

We present Playable Environments-a new representation for interactive video generation and manipulation in space and time. With a single image at inference time, our novel framework allows the user to move objects in 3D while generating a video by providing a sequence of desired actions. The actions are learnt in an unsupervised manner. The camera can be controlled to get the desired viewpoint. Our method builds an environment state for each frame, which can be manipulated by our proposed action mod-ule and decoded back to the image space with volumetric rendering. To support diverse appearances of objects, we extend neural radiance fields with style-based modulation. Our method trains on a collection of various monocular videos requiring only the estimated camera parameters and 2D object locations. To set a challenging benchmark, we in-troduce two large scale video datasets with significant cam-era movements. As evidenced by our experiments, playable environments enable several creative applications not at-tainable by prior video synthesis works, including playable 3D video generation, stylization and manipulation 1 1 willi-menapace.github.io/playable-environments-website

Metabolic network alterations as a supportive biomarker in dementia with Lewy bodies with preserved dopamine transmission

Purpose Metabolic network analysis of FDG-PET utilizes an index of inter-regional correlation of resting state glucose metabolism and has been proven to provide complementary information regarding the disease process in parkinsonian syndromes. The goals of this study were (i) to evaluate pattern similarities of glucose metabolism and network connectivity in dementia with Lewy bodies (DLB) subjects with subthreshold dopaminergic loss compared to advanced disease stages and to (ii) investigate metabolic network alterations of FDG-PET for discrimination of patients with early DLB from other neurodegenerative disorders (Alzheimer’s disease, Parkinson’s disease, multiple system atrophy) at individual patient level via principal component analysis (PCA). Methods FDG-PETs of subjects with probable or possible DLB (n = 22) without significant dopamine deficiency (z-score < 2 in putamen binding loss on DaT-SPECT compared to healthy controls (HC)) were scaled by global-mean, prior to volume-of-interest-based analyses of relative glucose metabolism. Single region metabolic changes and network connectivity changes were compared against HC (n = 23) and against DLB subjects with significant dopamine deficiency (n = 86). PCA was applied to test discrimination of patients with DLB from disease controls (n = 101) at individual patient level. Results Similar patterns of hypo- (parietal- and occipital cortex) and hypermetabolism (basal ganglia, limbic system, motor cortices) were observed in DLB patients with and without significant dopamine deficiency when compared to HC. Metabolic connectivity alterations correlated between DLB patients with and without significant dopamine deficiency (R2 = 0.597, p < 0.01). A PCA trained by DLB patients with dopamine deficiency and HC discriminated DLB patients without significant dopaminergic loss from other neurodegenerative parkinsonian disorders at individual patient level (area-under-the-curve (AUC): 0.912). Conclusion Disease-specific patterns of altered glucose metabolism and altered metabolic networks are present in DLB subjects without significant dopaminergic loss. Metabolic network alterations in FDG-PET can act as a supporting biomarker in the subgroup of DLB patients without significant dopaminergic loss at symptoms onset

On the role of the mesoscale circulation on an idealized coastal upwelling ecosystem

International audienceAn idealized circulation model of coastal upwelling coupled to an ecosystem model has been built to address the impact of features such as eddies and filaments emerging from mesoscale dynamics on a marine ecosystem. The model mimics coastal upwelling along an infinite straight coast with north-south cyclic boundary conditions. Thanks to the parametrization of the geostrophic onshore flow in the thermocline, the circulation captures the typical characteristics of a coastal upwelling region: an equatorward coastal jet, a poleward undercurrent along the continental slope and mesoscale eddies and filaments. This eddying three-dimensional simulation is compared to a two-dimensional simulation using the averaged velocity field of the first simulation as velocity field. This approach allows us to compare simulations having similar upwelling and nutrient input but differing in the nature of the flow. An offshore spreading of the phytoplankton bloom is found in the eddying simulation. The width of the productive coastal band is increased from 80 km to 200 km by the mesoscale activity. A biogeochemical budget carried out in a 300 km-wide coastal band provides evidence that mesoscale activity decreases the total phytoplankton content mainly by exporting a significant part of the surface phytoplankton below the euphotic layer. In presence of mesoscale activity, the downward and offshore export of phytoplankton, zooplankton and detritus significantly contributes to total export of organic matter out of the surface coastal ocean, whereas their contribution to export is weak in the two-dimensional case