Deep networks have recently enjoyed enormous success when applied to recognition and classification problems in computer vision 22, 33, but their use in graphics problems has been limited (23, 7 are ...notable recent exceptions). In this work, we present a novel deep architecture that performs new view synthesis directly from pixels, trained from a large number of posed image sets. In contrast to traditional approaches, which consist of multiple complex stages of processing, each of which requires careful tuning and can fail in unexpected ways, our system is trained end-to-end. The pixels from neighboring views of a scene are presented to the network, which then directly produces the pixels of the unseen view. The benefits of our approach include generality (we only require posed image sets and can easily apply our method to different domains), and high quality results on traditionally difficult scenes. We believe this is due to the end-to-end nature of our system, which is able to plausibly generate pixels according to color, depth, and texture priors learnt automatically from the training data. We show view interpolation results on imagery from the KITTI dataset 12, from data from 1 as well as on Google Street View images. To our knowledge, our work is the first to apply deep learning to the problem of new view synthesis from sets of real-world, natural imagery.
Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, ...the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences.
Gavialoid crocodylians are the archetypal longirostrine archosaurs and, as such, understanding their patterns of evolution is fundamental to recognizing cranial rearrangements and reconstructing ...adaptive pathways associated with elongation of the rostrum (longirostry). The living Indian gharial Gavialis gangeticus is the sole survivor of the group, thus providing unique evidence on the distinctive biology of its fossil kin. Yet phylogenetic relationships and evolutionary ecology spanning ~70 million-years of longirostrine crocodylian diversification remain unclear. Analysis of cranial anatomy of a new proto-Amazonian gavialoid, Gryposuchus pachakamue sp. nov., from the Miocene lakes and swamps of the Pebas Mega-Wetland System reveals that acquisition of both widely separated and protruding eyes (telescoped orbits) and riverine ecology within South American and Indian gavialoids is the result of parallel evolution. Phylogenetic and morphometric analyses show that, in association with longirostry, circumorbital bone configuration can evolve rapidly for coping with trends in environmental conditions and may reflect shifts in feeding strategy. Our results support a long-term radiation of the South American forms, with taxa occupying either extreme of the gavialoid morphospace showing preferences for coastal marine versus fluvial environments. The early biogeographic history of South American gavialoids was strongly linked to the northward drainage system connecting proto-Amazonian wetlands to the Caribbean region.
Form‐function relationships in mammalian feeding systems are active topics of research in evolutionary biology. This is due principally to their fundamental importance for understanding dietary ...adaptations in extinct taxa and macro‐evolutionary patterns of morphological transformations through changing environments. We hypothesize that three‐dimensional dental topographic metrics represent stronger predictors for dietary and other ecological variables than do linear measurements. To test this hypothesis, we measured three dental topographic metrics: Relief Index (RFI), Dirichlet Normal Energy (DNE), and Orientation Patch Count Rotated (OPCR) in 57 extant carnivoran species. Premolar and molar dental topographic indices were regressed against activity, diet breadth, habitat breadth, terrestriality, and trophic level variables within a phylogenetic framework. The results of this study showed significant correlations between RFI and the ecological variables diet breadth and trophic level. Weaker correlations are documented between OPCR and activity and between DNE and trophic level. Our results suggest that cusp height is strongly reflective of dietary ecology in carnivorans as a whole, and represents a proxy mainly for different degrees of hypercarnivory observed within this group of predatory mammals.
Dental topographic metrics represent stronger predictors for dietary and other ecological variables than do linear measurements. We measured three dental topographic metrics: Relief Index (RFI), Dirichlet Normal Energy (DNE), and Orientation Patch Count Rotated (OPCR) in 57 extant carnivoran species. Our results suggest that cusp height is strongly reflective of dietary ecology in carnivorans as a whole, and represents a proxy mainly for different degrees of hypercarnivory observed within this group of predatory mammals.
Carbon isotopic signatures recorded in vertebrate tissues derive from ingested food and thus reflect ecologies and ecosystems. For almost two decades, most carbon isotope-based ecological ...interpretations of extant and extinct herbivorous mammals have used a single diet-bioapatite enrichment value (14‰). Assuming this single value applies to all herbivorous mammals, from tiny monkeys to giant elephants, it overlooks potential effects of distinct physiological and metabolic processes on carbon fractionation. By analysing a never before assessed herbivorous group spanning a broad range of body masses-sloths-we discovered considerable variation in diet-bioapatite δ
C enrichment among mammals. Statistical tests (ordinary least squares, quantile, robust regressions, Akaike information criterion model tests) document independence from phylogeny, and a previously unrecognized strong and significant correlation of δ
C enrichment with body mass for all mammalian herbivores. A single-factor body mass model outperforms all other single-factor or more complex combinatorial models evaluated, including for physiological variables (metabolic rate and body temperature proxies), and indicates that body mass alone predicts δ
C enrichment. These analyses, spanning more than 5 orders of magnitude of body sizes, yield a size-dependent prediction of isotopic enrichment across Mammalia and for distinct digestive physiologies, permitting reconstruction of foregut versus hindgut fermentation for fossils and refined mean annual palaeoprecipitation estimates based on δ
C of mammalian bioapatite.
Although pediatric spinal deformity correction using pedicle screws has a very low rate of complications, the long-term consequences of screw malposition is unknown. CT navigation has been proposed ...to improve screw accuracy. The aim of this study was to determine whether intraoperative navigation during pedicle screw placement in pediatric scoliosis makes screw placement more accurate. We also examined radiation exposure, operative time blood loss and complications with and without the use of CT navigation in pediatric spinal deformity surgery.
A systematic review of the literature was conducted. After screening, 13 articles were qualitatively and quantitatively analyzed to be used for the review. A random effects meta-analysis using REML methodology was employed to compare outcomes of screw accuracy, estimated blood loss, radiation exposure, and surgical duration.
Screws placed with CT navigation surgery were three times as likely to be deemed "acceptable" compared with screws placed with freehand and 2D fluoroscopy assistance, twice as likely to be "perfect", and only 1/3 as likely to be potentially unsafe (all p value < 0.01). EBL was not significantly different between groups; however, operative time was roughly thirty minutes longer on average. Random effects analysis showed no significant difference in effective dose radiation while using CT navigation (p = 0.06).
This systematic review of the literature demonstrates that intraoperative navigation results in more accurate pedicle screw placement compared to non-navigated techniques. We found that blood loss was similar in navigated and non-navigated surgery. Operative time was found to be approximately a half hour longer on average in navigated compared to non-navigated surgery. Effective radiation dose trended higher in navigated cases compared to non-navigated cases but did not reach statistical significance.
Closed-canopy rainforests are important for climate (influencing atmospheric circulation, albedo, carbon storage, etc.) and ecology (harboring the highest biodiversity of continental regions). Of all ...rainforests, Amazonia is the world’s most diverse, including the highest mammalian species richness. However, little is known about niche structure, ecological roles, and food resource partitioning of Amazonian mammalian communities over time. Through analyses of δ13Cbioapatite, δ13Chair, and δ15Nhair, we isotopically characterized aspects of feeding ecology in a modern western Amazonian mammalian community in Peru, serving as a baseline for understanding the evolution of Neotropical rainforest ecosystems. By comparing these results with data from equatorial Africa, we evaluated the potential influences of distinct phylogenetic and biogeographic histories on the isotopic niches occupied by mammals in analogous tropical ecosystems. Our results indicate that, despite their geographical and taxonomic differences, median δ13Cdiet values from closed-canopy rainforests in Amazonia (−27.4‰) and equatorial Africa (−26.9‰) are not significantly different, and that the median δ13Cdiet expected for mammalian herbivores in any closed-canopy rainforest is −27.2‰. Amazonian mammals seem to exploit a narrower spectrum of dietary resources than equatorial African mammals, however, as depicted by the absence of highly negative δ¹3Cdiet values previously proposed as indicative of rainforests (<−31‰). Finally, results of keratin and bioapatite δ13C indicate that the predictive power of trophic relationships, and traditional dietary ecological classifications in bioapatite-protein isotopic offset expectations, must be reconsidered.
Amazonia contains one of the world's richest biotas, but origins of this diversity remain obscure. Onset of the Amazon River drainage at approximately 10.5 Ma represented a major shift in Neotropical ...ecosystems, and proto-Amazonian biotas just prior to this pivotal episode are integral to understanding origins of Amazonian biodiversity, yet vertebrate fossil evidence is extraordinarily rare. Two new species-rich bonebeds from late Middle Miocene proto-Amazonian deposits of northeastern Peru document the same hyperdiverse assemblage of seven co-occurring crocodylian species. Besides the large-bodied Purussaurus and Mourasuchus, all other crocodylians are new taxa, including a stem caiman—Gnatusuchus pebasensis—bearing a massive shovel-shaped mandible, procumbent anterior and globular posterior teeth, and a mammal-like diastema. This unusual species is an extreme exemplar of a radiation of small caimans with crushing dentitions recording peculiar feeding strategies correlated with a peak in proto-Amazonian molluscan diversity and abundance. These faunas evolved within dysoxic marshes and swamps of the long-lived Pebas Mega-Wetland System and declined with inception of the transcontinental Amazon drainage, favouring diversification of longirostrine crocodylians and more modern generalist-feeding caimans. The rise and demise of distinctive, highly productive aquatic ecosystems substantially influenced evolution of Amazonian biodiversity hotspots of crocodylians and other organisms throughout the Neogene.
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