52 research outputs found
Nickell Bias in Panel Local Projection: Financial Crises Are Worse Than You Think
Local Projection is widely used for impulse response estimation, with the
Fixed Effect (FE) estimator being the default for panel data. This paper
highlights the presence of Nickell bias for all regressors in the FE estimator,
even if lagged dependent variables are absent in the regression. This bias is
the consequence of the inherent panel predictive specification. We recommend
using the split-panel jackknife estimator to eliminate the asymptotic bias and
restore the standard statistical inference. Revisiting three macro-finance
studies on the linkage between financial crises and economic contraction, we
find that the FE estimator substantially underestimates the post-crisis
economic losses
The boosted HP filter is more general than you might think
The global financial crisis and Covid recession have renewed discussion
concerning trend-cycle discovery in macroeconomic data, and boosting has
recently upgraded the popular HP filter to a modern machine learning device
suited to data-rich and rapid computational environments. This paper sheds
light on its versatility in trend-cycle determination, explaining in a simple
manner both HP filter smoothing and the consistency delivered by boosting for
general trend detection. Applied to a universe of time series in FRED
databases, boosting outperforms other methods in timely capturing downturns at
crises and recoveries that follow. With its wide applicability the boosted HP
filter is a useful automated machine learning addition to the macroeconometric
toolkit
SHERF: Generalizable Human NeRF from a Single Image
Existing Human NeRF methods for reconstructing 3D humans typically rely on
multiple 2D images from multi-view cameras or monocular videos captured from
fixed camera views. However, in real-world scenarios, human images are often
captured from random camera angles, presenting challenges for high-quality 3D
human reconstruction. In this paper, we propose SHERF, the first generalizable
Human NeRF model for recovering animatable 3D humans from a single input image.
SHERF extracts and encodes 3D human representations in canonical space,
enabling rendering and animation from free views and poses. To achieve
high-fidelity novel view and pose synthesis, the encoded 3D human
representations should capture both global appearance and local fine-grained
textures. To this end, we propose a bank of 3D-aware hierarchical features,
including global, point-level, and pixel-aligned features, to facilitate
informative encoding. Global features enhance the information extracted from
the single input image and complement the information missing from the partial
2D observation. Point-level features provide strong clues of 3D human
structure, while pixel-aligned features preserve more fine-grained details. To
effectively integrate the 3D-aware hierarchical feature bank, we design a
feature fusion transformer. Extensive experiments on THuman, RenderPeople,
ZJU_MoCap, and HuMMan datasets demonstrate that SHERF achieves state-of-the-art
performance, with better generalizability for novel view and pose synthesis.Comment: Accepted by ICCV2023. Project webpage:
https://skhu101.github.io/SHERF
PrimDiffusion: Volumetric Primitives Diffusion for 3D Human Generation
We present PrimDiffusion, the first diffusion-based framework for 3D human
generation. Devising diffusion models for 3D human generation is difficult due
to the intensive computational cost of 3D representations and the articulated
topology of 3D humans. To tackle these challenges, our key insight is operating
the denoising diffusion process directly on a set of volumetric primitives,
which models the human body as a number of small volumes with radiance and
kinematic information. This volumetric primitives representation marries the
capacity of volumetric representations with the efficiency of primitive-based
rendering. Our PrimDiffusion framework has three appealing properties: 1)
compact and expressive parameter space for the diffusion model, 2) flexible 3D
representation that incorporates human prior, and 3) decoder-free rendering for
efficient novel-view and novel-pose synthesis. Extensive experiments validate
that PrimDiffusion outperforms state-of-the-art methods in 3D human generation.
Notably, compared to GAN-based methods, our PrimDiffusion supports real-time
rendering of high-quality 3D humans at a resolution of once the
denoising process is done. We also demonstrate the flexibility of our framework
on training-free conditional generation such as texture transfer and 3D
inpainting.Comment: NeurIPS 2023; Project page
https://frozenburning.github.io/projects/primdiffusion/ Code available at
https://github.com/FrozenBurning/PrimDiffusio
Performance of a new Candida anti-mannan IgM and IgG assays in the diagnosis of candidemia
Candida is one of the most frequent pathogens of bloodstream infections, which is associated with high morbidity and mortality rates. Rapid immunological detection methods are essential in the early diagnosis of candidemia. Anti-mannan is one of host-derived biomarkers against cell wall components of Candida. We conducted this study to evaluate the diagnostic performance of two anti-mannan assays (IgM, IgG) for candidemia through the analysis of 40 candidemia patients, 48 participants with Candida colonization and 213 participants with neither Candida colonization nor Candida infections (13 patients with other bloodstream infections, 145 hospitalized patients and 55 healthy controls). The performance of the two assays were evaluated by calculating their sensitivity and specificity. The sensitivity ranged from 0.78 to 0.80 for the IgM assay and 0.68 to 0.75 for the IgG assay. The specificity ranged from 0.97 to 0.98 for the IgM assay and 0.91 to 0.94 for the IgG assay. The diagnostic performance of the anti-mannan IgM assay was better than that of IgG, with higher sensitivity and specificity. Combining the two assays (positive results of single or both assays are both considered as positive) could improve the sensitivity up to 0.93 (0.79-0.98) and only slightly reduce the specificity (0.93(0.89-0.95)). The anti-mannan IgM, IgG assays are rapid and cost-effective assays that may be probably useful in the diagnosis of candidemia
Machine learning-based evaluation of application value of pulse wave parameter model in the diagnosis of hypertensive disorder in pregnancy
Hypertensive disorder in pregnancy (HDP) remains a major health burden, and it is associated with systemic cardiovascular adaptation. The pulse wave is an important basis for evaluating the status of the human cardiovascular system. This research aims to evaluate the application value of pulse waves in the diagnosis of hypertensive disorder in pregnancy.This research a retrospective study of pregnant women who attended prenatal care and labored at Beijing Haidian District Maternal and Child Health Hospital. We extracted maternal hemodynamic factors and measured the pulse wave of the pregnant women. We developed an HDP predictive model by using support vector machine algorithms at five-gestational-week stages.At five-gestational-week stages, the area under the receiver operating characteristic curve (AUC) of the predictive model with pulse wave parameters was higher than that of the predictive model with hemodynamic factors. The AUC values of the predictive model with pulse wave parameters were 0.77 (95% CI 0.64 to 0.9), 0.83 (95% CI 0.77 to 0.9), 0.85 (95% CI 0.81 to 0.9), 0.93 (95% CI 0.9 to 0.96) and 0.88 (95% CI 0.8 to 0.95) at five-gestational-week stages, respectively. Compared to the predictive models with hemodynamic factors, the predictive model with pulse wave parameters had better prediction effects on HDP.Pulse waves had good predictive effects for HDP and provided appropriate guidance and a basis for non-invasive detection of HDP
SMPLer-X: Scaling Up Expressive Human Pose and Shape Estimation
Expressive human pose and shape estimation (EHPS) unifies body, hands, and
face motion capture with numerous applications. Despite encouraging progress,
current state-of-the-art methods still depend largely on a confined set of
training datasets. In this work, we investigate scaling up EHPS towards the
first generalist foundation model (dubbed SMPLer-X), with up to ViT-Huge as the
backbone and training with up to 4.5M instances from diverse data sources. With
big data and the large model, SMPLer-X exhibits strong performance across
diverse test benchmarks and excellent transferability to even unseen
environments. 1) For the data scaling, we perform a systematic investigation on
32 EHPS datasets, including a wide range of scenarios that a model trained on
any single dataset cannot handle. More importantly, capitalizing on insights
obtained from the extensive benchmarking process, we optimize our training
scheme and select datasets that lead to a significant leap in EHPS
capabilities. 2) For the model scaling, we take advantage of vision
transformers to study the scaling law of model sizes in EHPS. Moreover, our
finetuning strategy turn SMPLer-X into specialist models, allowing them to
achieve further performance boosts. Notably, our foundation model SMPLer-X
consistently delivers state-of-the-art results on seven benchmarks such as
AGORA (107.2 mm NMVE), UBody (57.4 mm PVE), EgoBody (63.6 mm PVE), and EHF
(62.3 mm PVE without finetuning). Homepage:
https://caizhongang.github.io/projects/SMPLer-X/Comment: Homepage: https://caizhongang.github.io/projects/SMPLer-X
SynBody: Synthetic Dataset with Layered Human Models for 3D Human Perception and Modeling
Synthetic data has emerged as a promising source for 3D human research as it
offers low-cost access to large-scale human datasets. To advance the diversity
and annotation quality of human models, we introduce a new synthetic dataset,
SynBody, with three appealing features: 1) a clothed parametric human model
that can generate a diverse range of subjects; 2) the layered human
representation that naturally offers high-quality 3D annotations to support
multiple tasks; 3) a scalable system for producing realistic data to facilitate
real-world tasks. The dataset comprises 1.2M images with corresponding accurate
3D annotations, covering 10,000 human body models, 1,187 actions, and various
viewpoints. The dataset includes two subsets for human pose and shape
estimation as well as human neural rendering. Extensive experiments on SynBody
indicate that it substantially enhances both SMPL and SMPL-X estimation.
Furthermore, the incorporation of layered annotations offers a valuable
training resource for investigating the Human Neural Radiance Fields (NeRF).Comment: Accepted by ICCV 2023. Project webpage: https://synbody.github.io
Digital Life Project: Autonomous 3D Characters with Social Intelligence
In this work, we present Digital Life Project, a framework utilizing language
as the universal medium to build autonomous 3D characters, who are capable of
engaging in social interactions and expressing with articulated body motions,
thereby simulating life in a digital environment. Our framework comprises two
primary components: 1) SocioMind: a meticulously crafted digital brain that
models personalities with systematic few-shot exemplars, incorporates a
reflection process based on psychology principles, and emulates autonomy by
initiating dialogue topics; 2) MoMat-MoGen: a text-driven motion synthesis
paradigm for controlling the character's digital body. It integrates motion
matching, a proven industry technique to ensure motion quality, with
cutting-edge advancements in motion generation for diversity. Extensive
experiments demonstrate that each module achieves state-of-the-art performance
in its respective domain. Collectively, they enable virtual characters to
initiate and sustain dialogues autonomously, while evolving their
socio-psychological states. Concurrently, these characters can perform
contextually relevant bodily movements. Additionally, a motion captioning
module further allows the virtual character to recognize and appropriately
respond to human players' actions. Homepage: https://digital-life-project.com/Comment: Homepage: https://digital-life-project.com
Ultrathin Si/CNTs Paper-Like Composite for Flexible Li-Ion Battery Anode With High Volumetric Capacity
Thin and lightweight flexible lithium-ion batteries (LIBs) with high volumetric capacities are crucial for the development of flexible electronic devices. In the present work, we reported a paper-like ultrathin and flexible Si/carbon nanotube (CNT) composite anode for LIBs, which was realized by conformal electrodeposition of a thin layer of silicon on CNTs at ambient temperature. This method was quite simple and easy to scale up with low cost as compared to other deposition techniques, such as sputtering or CVD. The flexible Si/CNT composite exhibited high volumetric capacities in terms of the total volume of active material and current collector, surpassing the most previously reported Si-based flexible electrodes at various rates. In addition, the poor initial coulombic efficiency of the Si/CNT composites can be effectively improved by prelithiation treatment and a commercial red LED can be easily lighted by a full pouch cell using a Si/CNT composite as a flexible anode under flat or bent states. Therefore, the ultrathin and flexible Si/CNT composite is highly attractive as an anode material for flexible LIBs
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