61 research outputs found
Representing Volumetric Videos as Dynamic MLP Maps
This paper introduces a novel representation of volumetric videos for
real-time view synthesis of dynamic scenes. Recent advances in neural scene
representations demonstrate their remarkable capability to model and render
complex static scenes, but extending them to represent dynamic scenes is not
straightforward due to their slow rendering speed or high storage cost. To
solve this problem, our key idea is to represent the radiance field of each
frame as a set of shallow MLP networks whose parameters are stored in 2D grids,
called MLP maps, and dynamically predicted by a 2D CNN decoder shared by all
frames. Representing 3D scenes with shallow MLPs significantly improves the
rendering speed, while dynamically predicting MLP parameters with a shared 2D
CNN instead of explicitly storing them leads to low storage cost. Experiments
show that the proposed approach achieves state-of-the-art rendering quality on
the NHR and ZJU-MoCap datasets, while being efficient for real-time rendering
with a speed of 41.7 fps for images on an RTX 3090 GPU. The
code is available at https://zju3dv.github.io/mlp_maps/.Comment: Accepted to CVPR 2023. The first two authors contributed equally to
this paper. Project page: https://zju3dv.github.io/mlp_maps
Umbilical artery Doppler indices in small for gestational age fetuses: Correlation with adverse outcomes and placental abnormalities
Efficient Neural Radiance Fields for Interactive Free-viewpoint Video
This paper aims to tackle the challenge of efficiently producing interactive
free-viewpoint videos. Some recent works equip neural radiance fields with
image encoders, enabling them to generalize across scenes. When processing
dynamic scenes, they can simply treat each video frame as an individual scene
and perform novel view synthesis to generate free-viewpoint videos. However,
their rendering process is slow and cannot support interactive applications. A
major factor is that they sample lots of points in empty space when inferring
radiance fields. We propose a novel scene representation, called ENeRF, for the
fast creation of interactive free-viewpoint videos. Specifically, given
multi-view images at one frame, we first build the cascade cost volume to
predict the coarse geometry of the scene. The coarse geometry allows us to
sample few points near the scene surface, thereby significantly improving the
rendering speed. This process is fully differentiable, enabling us to jointly
learn the depth prediction and radiance field networks from RGB images.
Experiments on multiple benchmarks show that our approach exhibits competitive
performance while being at least 60 times faster than previous generalizable
radiance field methods.Comment: SIGGRAPH Asia 2022; Project page: https://zju3dv.github.io/enerf
Relightable and Animatable Neural Avatar from Sparse-View Video
This paper tackles the challenge of creating relightable and animatable
neural avatars from sparse-view (or even monocular) videos of dynamic humans
under unknown illumination. Compared to studio environments, this setting is
more practical and accessible but poses an extremely challenging ill-posed
problem. Previous neural human reconstruction methods are able to reconstruct
animatable avatars from sparse views using deformed Signed Distance Fields
(SDF) but cannot recover material parameters for relighting. While
differentiable inverse rendering-based methods have succeeded in material
recovery of static objects, it is not straightforward to extend them to dynamic
humans as it is computationally intensive to compute pixel-surface intersection
and light visibility on deformed SDFs for inverse rendering. To solve this
challenge, we propose a Hierarchical Distance Query (HDQ) algorithm to
approximate the world space distances under arbitrary human poses.
Specifically, we estimate coarse distances based on a parametric human model
and compute fine distances by exploiting the local deformation invariance of
SDF. Based on the HDQ algorithm, we leverage sphere tracing to efficiently
estimate the surface intersection and light visibility. This allows us to
develop the first system to recover animatable and relightable neural avatars
from sparse view (or monocular) inputs. Experiments demonstrate that our
approach is able to produce superior results compared to state-of-the-art
methods. Our code will be released for reproducibility.Comment: Project page: https://zju3dv.github.io/relightable_avata
Topological Magnetoresistance of Magnetic Skyrmionic Bubbles
Magnetic skyrmions offer promising prospects for constructing future
energy-efficient and high-density information technology, leading to extensive
explorations of new skyrmionic materials recently. The topological Hall effect
has been widely adopted as a distinctive marker of skyrmion emergence.
Alternately, here we propose a novel signature of skyrmion state by
quantitatively investigating the magnetoresistance (MR) induced by skyrmionic
bubbles in CeMn2Ge2. An intriguing finding was revealed: the anomalous MR
measured at different temperatures can be normalized into a single curve,
regardless of sample thickness. This behavior can be accurately reproduced by
the recent chiral spin textures MR model. Further analysis of the MR anomaly
allowed us to quantitatively examine the effective magnetic fields of various
scattering channels. Remarkably, the analyses, combined with the Lorentz
transmission electronic microscopy results, indicate that the in-plane
scattering channel with triplet exchange interactions predominantly governs the
magnetotransport in the Bloch-type skyrmionic bubble state. Our results not
only provide insights into the quantum correction on MR induced by skyrmionic
bubble phase, but also present an electrical probing method for studying chiral
spin texture formation, evolution and their topological properties, which opens
up exciting possibilities for identifying new skyrmionic materials and
advancing the methodology for studying chiral spin textures.Comment: 17 pages,5 figures,submitte
Development of Resistance to EGFR-Targeted Therapy in Malignant Glioma Can Occur through EGFR-Dependent and -Independent Mechanisms
Exclusive Breastfeeding Practices in Relation to Social and Health Determinants: a Comparison of the 2006 and 2011 Nepal Demographic and Health Surveys
Background: Exclusive breastfeeding (EBF) for the first six months can have a significant impact on reducing child morbidity and mortality rates. The objective of this study was to compare the determinants of and trends in EBF in infants =5 months from the 2006 and 2011 Nepal Demographic and Health Surveys. Methods: Data on mother/infant pairs having infants of =5 months from 2006 (n = 482) and 2011 (n = 227) were analysed. The EBF rate, determinants of EBF, and changes in EBF rates between the 2006 and 2011 surveys were examined using Chi-square test and multiple logistic regression. Results: The EBF rate for =5 months in 2006 was 53.2% (95% CI, 47.1%-59.3%) and 66.3% (95% CI, 56.6%-74.8%) in 2011. In 2006, infants =4 months were more likely to be EBF [(aOR) 3.086, 95% CI (1.825-5.206)] after controlling for other factors. A geographic effect was also found in this study, with the odds of EBF higher for infants from the Hills [aOR 3.426, 95% CI (1.568-7.474)] compared to those form the mountains. The odds of EBF were also higher for higher order infants [aOR 1.968, 95% CI (1.020-3.799)]. Infants whose fathers belonged to non-agricultural occupation were less likely to be provided with EBF. Infants who were delivered in the home were more likely to experience EBF [aOR 1.886; 95% CI (1.044-3.407)]. In 2011, infants of age =4 months were more likely [aOR 4.963, 95% CI (2.317-10.629)] to have been breastfed exclusively. While there was an increase in the EBF rate between 2006 and 2011 surveys, the significant increase was noticed only among the infants of four months [32.0%; 95% CI (19.9%-47.0%)] in 2006 to [65.5%; 95% CI (48.1-79.6)] in 2011.Conclusions: The proportion of infants who were EBF was higher in Nepal in 2011survey compared to 2006 survey; however, this is still below the recommended WHO target of 90%. Infantâs age, ecological region, parity and fatherâs occupation were associated with EBF. Further interventions such as peer counselling, antenatal counselling and involving fathers in the community to promote EBF in Nepal are recommended
Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).
Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and â„1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (nâ=â5069) or prospectively (nâ=â5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (â€6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; pâ=â0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)
Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.
BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362
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