234 research outputs found

    OccWorld: Learning a 3D Occupancy World Model for Autonomous Driving

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    Understanding how the 3D scene evolves is vital for making decisions in autonomous driving. Most existing methods achieve this by predicting the movements of object boxes, which cannot capture more fine-grained scene information. In this paper, we explore a new framework of learning a world model, OccWorld, in the 3D Occupancy space to simultaneously predict the movement of the ego car and the evolution of the surrounding scenes. We propose to learn a world model based on 3D occupancy rather than 3D bounding boxes and segmentation maps for three reasons: 1) expressiveness. 3D occupancy can describe the more fine-grained 3D structure of the scene; 2) efficiency. 3D occupancy is more economical to obtain (e.g., from sparse LiDAR points). 3) versatility. 3D occupancy can adapt to both vision and LiDAR. To facilitate the modeling of the world evolution, we learn a reconstruction-based scene tokenizer on the 3D occupancy to obtain discrete scene tokens to describe the surrounding scenes. We then adopt a GPT-like spatial-temporal generative transformer to generate subsequent scene and ego tokens to decode the future occupancy and ego trajectory. Extensive experiments on the widely used nuScenes benchmark demonstrate the ability of OccWorld to effectively model the evolution of the driving scenes. OccWorld also produces competitive planning results without using instance and map supervision. Code: https://github.com/wzzheng/OccWorld.Comment: Code is available at: https://github.com/wzzheng/OccWorl

    Geochemistry and geochronology of dolerite dykes from the Daba and Dongbo peridotite massifs, SW Tibet: Insights into the style of mantle melting at the onset of Neo-Tethyan subduction

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    This study reports compositional and whole-rock Sr-Nd isotope data as well as zircon U-Pb geochronological data on dolerite dikes from the Daba and Dongbo ultramafic massifs, southwest Yarlung-Zangbo Suture Zone (YZSZ), Tibet. The 120.6 \ub1 1.6 Ma dolerite dikes from the Daba peridotite exhibit normal mid-ocean ridge basalt (N-MORB)-type normalized mutli-element patterns [(La/Yb)N = 0.43-0.72] with noticeable negative Nb and Th anomalies. They have high initial 87Sr/8624 Sr ratios (87Sr/8625 Sr(i) = 0.70720-0.70788) and high \u3b5Nd(t) values (+7.4 to +7.9). The 125.4 \ub1 1.8 Ma dolerite intrusions within the Dongbo peridotite show N-MORB\u2012type trace element profiles [(La/Yb)N = 0.65-0.84] characterized by apparent negative anomalies in Nb and Th, and mild negative anomalies in Ti (\ub1 Y). They also have high 87Sr/8629 Sr(i) ratios (0.70611-0.70679) and elevated \u3b5Nd(t) values (+7.8 to +8.2). Semi-quantitative La/Yb vs. Dy/Yb modeling demonstrates that the parental magmas of the investigated dolerite dikes derived from more than 20% (cumulative) melting of a (broad) mantle source region that had a spinel-bearing N-MORB\u2013like lherzolitic composition. Our geochemical and isotopic data indicate that the composition of the inferred mantle source was influenced by minor input of subducted crustal material. The petrogenesis of the Daba and Dongbo massifs could be linked to upwelling of an asthenospheric source that caused continental rift and subsequent seafloor spreading, followed by subduction initiation adjacent to a passive margin during the early Cretaceous (~130-120 Ma). Our study provides a more detailed, and perhaps more elegant, hypothesis for the tectono-magmatic evolution of the southwestern YZSZ "ophiolitic" peridotites after their accretion beneath a Neo-Tethyan marginal basin

    Alterations in cytoskeletal and Ca2+ cycling regulators in atria lacking the obscurin Ig58/59 module

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    IntroductionObscurin (720–870 kDa) is a giant cytoskeletal and signaling protein that possesses both structural and regulatory functions in striated muscles. Immunoglobulin domains 58/59 (Ig58/59) of obscurin bind to a diverse set of proteins that are essential for the proper structure and function of the heart, including giant titin, novex-3, and phospholamban (PLN). Importantly, the pathophysiological significance of the Ig58/59 module has been further underscored by the discovery of several mutations within Ig58/59 that are linked to various forms of myopathy in humans. We previously generated a constitutive deletion mouse model, Obscn-ΔIg58/59, that expresses obscurin lacking Ig58/59, and characterized the effects of this deletion on cardiac morphology and function through aging. Our findings demonstrated that Obscn-ΔIg58/59 male animals develop severe arrhythmia, primarily manifesting as episodes of junctional escape and spontaneous loss of regular p-waves, reminiscent of human atrial fibrillation, accompanied by significant atrial enlargement that progresses in severity with aging.Methods and ResultsTo comprehensively characterize the molecular alterations responsible for these pathologies, we performed proteomic and phospho-proteomic analyses in aging Obscn-ΔIg58/59 atria. Our studies revealed extensive and novel alterations in the expression and phosphorylation profile of major cytoskeletal proteins, Ca2+ regulators, and Z-disk associated protein complexes in the Obscn-ΔIg58/59 atria through aging.DiscussionThese studies implicate obscurin, particularly the Ig58/59 module, as an essential regulator of the Z-disk associated cytoskeleton and Ca2+ cycling in the atria and provide new molecular insights into the development of atrial fibrillation and remodeling

    Coexistence of MORB- and OIB-like dolerite intrusions in the Purang ultramafic massif, SW Tibet: a paradigm of plume-influenced MOR-type magmatism prior to subduction initiation in the Neo-Tethyan lithospheric mantle

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    The Yarlung Zangbo Suture Zone (YZSZ) of South Tibet is divided by the Zhongba-Zhada terrane into two subparallel ophiolitic belts in its western end. The peridotite massifs of the southern belt tectonically overlie the Tethyan Himalaya sequence. The Purang peridotite body in this belt is intruded by two groups of dolerite dikes, providing significant compositional, geochronological, and isotopic information about the melting history of the Neo-Tethyan mantle. U-Pb ages of zircons separated from dolerites show that peridotites of West Purang were intruded by an early generation of dikes at 138.5 \ub1 2.0 Ma (Valanginian). These dolerites show ocean island basalt (OIB)-type normalized multi-elemental profiles and Sr-Nd isotopic signatures [(La/Yb)N = 13\u201316], high initial 87Sr/86Sr ratios (0.70598\u20130.70765), and low \u3b5Nd(t) values (\u20132.6 to \u20132.3). Zircons separated from this group of dolerites have slightly radiogenic \u3b5Hf(t) values (+2.6 to +4.6). The next generation of dolerite dikes intruded the East Purang peridotites between 124.5 \ub1 2.5 Ma and 124.4 \ub1 3.2 Ma (Aptian). These East Purang dolerites show normal mid-ocean ridge basalt (N-MORB)-type normalized multi-element patterns [(La/Yb)N = 0.6\u20130.9] with noticeable negative Nb and Th (\ub1Ti) anomalies, and have high 87Sr/86Sr(i) (0.70295\u20130.70618) and high \u3b5Nd(t) values (+7.7 to +9.2). Zircons separated from the East Purang dolerites show strongly radiogenic \u3b5Hf(t) values (+3.5 to +17.0). Semiquantitative geochemical modeling demonstrates that the parental magmas of West Purang dolerites were generated from 5%\u201310% polybaric partial melting of a deep-seated juvenile asthenospheric source enriched by plume-type components. In contrast, the parental melts of East Purang dolerites were derived from more than 20% melting of a juvenile spinel-bearing MORBtype mantle source that was modified by subduction-related melts/fluids to a minor extent. A possible tectono-magmatic model for the petrogenesis of the Purang ophiolitic massif could be linked to incipient continental rifting and subsequent oceanic seafloor spreading associated with decompression upwelling of an asthenospheric source contaminated by plume-type components. This plume-proximal seafloor spreading-system was succeeded by the initiation of Neo-Tethyan intra-oceanic subduction close to the active continental margin of Eurasia during the Early Cretaceous
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