120 research outputs found
Inference on gravitational waves from coalescences of stellar-mass compact objects and intermediate-mass black holes
Gravitational waves from coalescences of neutron stars or stellar-mass black
holes into intermediate-mass black holes (IMBHs) of solar masses
represent one of the exciting possible sources for advanced gravitational-wave
detectors. These sources can provide definitive evidence for the existence of
IMBHs, probe globular-cluster dynamics, and potentially serve as tests of
general relativity. We analyse the accuracy with which we can measure the
masses and spins of the IMBH and its companion in intermediate-mass ratio
coalescences. We find that we can identify an IMBH with a mass above with confidence provided the massive body exceeds . For source masses above , the best measured
parameter is the frequency of the quasi-normal ringdown. Consequently, the
total mass is measured better than the chirp mass for massive binaries, but the
total mass is still partly degenerate with spin, which cannot be accurately
measured. Low-frequency detector sensitivity is particularly important for
massive sources, since sensitivity to the inspiral phase is critical for
measuring the mass of the stellar-mass companion. We show that we can
accurately infer source parameters for cosmologically redshifted signals by
applying appropriate corrections. We investigate the impact of uncertainty in
the model gravitational waveforms and conclude that our main results are likely
robust to systematics.Comment: 9 pages, 11 figure
Gender Differences in Clinical Outcomes of Patients with Coronary Artery Disease after Percutaneous Coronary Intervention
With the increasing incidence of coronary artery disease, the percutaneous coronary intervention (PCI) has become one of the most effective treatments for coronary artery disease. After more than 40 years of clinical application, development and research, and continuous improvement, it has been widely used around the world. In recent years, due to the continuous innovation of drug-eluting stents, equipment, drugs, and interventional technology, the indications for treatment have been continuously broadened, many heart centers can deal with complete revascularization for high-risk indicated patient session, and the efficacy has been further improved. However, studies have shown that there are gender differences in the clinical prognosis of patients with coronary artery disease after percutaneous coronary intervention, which are affected by many related risk factors of gender differences, but there is lack of systematic and comprehensive review of relevant factors. The purpose of this review is to evaluate the possible causes of gender differences in the clinical outcomes of patients after percutaneous coronary intervention and to put forward recommendations for primary prevention and secondary prevention
Retrieving Precipitable Water Vapor From Shipborne Multi‐GNSS Observations
©2019. American Geophysical UnionPrecipitable water vapor (PWV) is an important parameter for climate research and a crucial factor to achieve high accuracy in satellite geodesy and satellite altimetry. Currently Global Navigation Satellite System (GNSS) PWV retrieval using static Precise Point Positioning is limited to ground stations. We demonstrated the PWV retrieval using kinematic Precise Point Positioning method with shipborne GNSS observations during a 20‐day experiment in 2016 in Fram Strait, the region of the Arctic Ocean between Greenland and Svalbard. The shipborne GNSS PWV shows an agreement of ~1.1 mm with numerical weather model data and radiosonde observations, and a root‐mean‐square of ~1.7 mm compared to Satellite with ARgos and ALtiKa PWV. An improvement of 10% is demonstrated with the multi‐GNSS compared to the Global Positioning System solution. The PWV retrieval was conducted under different sea state from calm water up to gale. Such shipborne GNSS PWV has the promising potential to improve numerical weather forecasts and satellite altimetry
Self-Supervised High Dynamic Range Imaging with Multi-Exposure Images in Dynamic Scenes
Merging multi-exposure images is a common approach for obtaining high dynamic
range (HDR) images, with the primary challenge being the avoidance of ghosting
artifacts in dynamic scenes. Recent methods have proposed using deep neural
networks for deghosting. However, the methods typically rely on sufficient data
with HDR ground-truths, which are difficult and costly to collect. In this
work, to eliminate the need for labeled data, we propose SelfHDR, a
self-supervised HDR reconstruction method that only requires dynamic
multi-exposure images during training. Specifically, SelfHDR learns a
reconstruction network under the supervision of two complementary components,
which can be constructed from multi-exposure images and focus on HDR color as
well as structure, respectively. The color component is estimated from aligned
multi-exposure images, while the structure one is generated through a
structure-focused network that is supervised by the color component and an
input reference (\eg, medium-exposure) image. During testing, the learned
reconstruction network is directly deployed to predict an HDR image.
Experiments on real-world images demonstrate our SelfHDR achieves superior
results against the state-of-the-art self-supervised methods, and comparable
performance to supervised ones. Codes are available at
https://github.com/cszhilu1998/SelfHDRComment: ICLR 202
Validation of 7 Years in-Flight HY-2A Calibration Microwave Radiometer Products Using Numerical Weather Model and Radiosondes
Haiyang-2A (HY-2A) has been working in-flight for over seven years, and the accuracy of HY-2A calibration microwave radiometer (CMR) data is extremely important for the wet troposphere delay correction (WTC) in sea surface height (SSH) determination. We present a comprehensive evaluation of the HY-2A CMR observation using the numerical weather model (NWM) for all the data available period from October 2011 to February 2018, including the WTC and the precipitable water vapor (PWV). The ERA(ECMWF Re-Analysis)-Interim products from European Centre for Medium-Range Weather Forecasts (ECMWF) are used for the validation of HY-2A WTC and PWV products. In general, a global agreement of root-mean-square (RMS) of 2.3 cm in WTC and 3.6 mm in PWV are demonstrated between HY-2A observation and ERA-Interim products. Systematic biases are revealed where before 2014 there was a positive WTC/PWV bias and after that, a negative one. Spatially, HY-2A CMR products show a larger bias in polar regions compared with mid-latitude regions and tropical regions and agree better in the Antarctic than in the Arctic with NWM. Moreover, HY-2A CMR products have larger biases in the coastal area, which are all caused by the brightness temperature (TB) contamination from land or sea ice. Temporally, the WTC/PWV biases increase from October 2011 to March 2014 with a systematic bias over 1 cm in WTC and 2 mm in PWV, and the maximum RMS values of 4.62 cm in WTC and 7.61 mm in PWV occur in August 2013, which is because of the unsuitable retrieval coefficients and systematic TB measurements biases from 37 GHz band. After April 2014, the TB bias is corrected, HY-2A CMR products agree very well with NWM from April 2014 to May 2017 with the average RMS of 1.68 cm in WTC and 2.65 mm in PWV. However, since June 2017, TB measurements from the 18.7 GHz band become unstable, which led to the huge differences between HY-2A CMR products and the NWM with an average RMS of 2.62 cm in WTC and 4.33 mm in PWV. HY-2A CMR shows high accuracy when three bands work normally and further calibration for HY-2A CMR is in urgent need. Furtherly, 137 global coastal radiosonde stations were used to validate HY-2A CMR. The validation based on radiosonde data shows the same variation trend in time of HY-2A CMR compared to the results from ECMWF, which verifies the results from ECMWF
Efficient Global Robustness Certification of Neural Networks via Interleaving Twin-Network Encoding
The robustness of deep neural networks has received significant interest recently, especially when being deployed in safety-critical systems, as it is important to analyze how sensitive the model output is under input perturbations. While most previous works focused on the local robustness property around an input sample, the studies of the global robustness property, which bounds the maximum output change under perturbations over the entire input space, are still lacking. In this work, we formulate the global robustness certification for neural networks with ReLU activation functions as a mixed-integer linear programming (MILP) problem, and present an efficient approach to address it. Our approach includes a novel interleaving twin-network encoding scheme, where two copies of the neural network are encoded side-by-side with extra interleaving dependencies added between them, and an over-approximation algorithm leveraging relaxation and refinement techniques to reduce complexity. Experiments demonstrate the timing efficiency of our work when compared with previous global robustness certification methods and the tightness of our over-approximation. A case study of closed-loop control safety verification is conducted, and demonstrates the importance and practicality of our approach for certifying the global robustness of neural networks in safety-critical systems
Collaborative Multi-Agent Video Fast-Forwarding
Multi-agent applications have recently gained significant popularity. In many
computer vision tasks, a network of agents, such as a team of robots with
cameras, could work collaboratively to perceive the environment for efficient
and accurate situation awareness. However, these agents often have limited
computation, communication, and storage resources. Thus, reducing resource
consumption while still providing an accurate perception of the environment
becomes an important goal when deploying multi-agent systems. To achieve this
goal, we identify and leverage the overlap among different camera views in
multi-agent systems for reducing the processing, transmission and storage of
redundant/unimportant video frames. Specifically, we have developed two
collaborative multi-agent video fast-forwarding frameworks in distributed and
centralized settings, respectively. In these frameworks, each individual agent
can selectively process or skip video frames at adjustable paces based on
multiple strategies via reinforcement learning. Multiple agents then
collaboratively sense the environment via either 1) a consensus-based
distributed framework called DMVF that periodically updates the fast-forwarding
strategies of agents by establishing communication and consensus among
connected neighbors, or 2) a centralized framework called MFFNet that utilizes
a central controller to decide the fast-forwarding strategies for agents based
on collected data. We demonstrate the efficacy and efficiency of our proposed
frameworks on a real-world surveillance video dataset VideoWeb and a new
simulated driving dataset CarlaSim, through extensive simulations and
deployment on an embedded platform with TCP communication. We show that
compared with other approaches in the literature, our frameworks achieve better
coverage of important frames, while significantly reducing the number of frames
processed at each agent.Comment: IEEE Transactions on Multimedia, 2023. arXiv admin note: text overlap
with arXiv:2008.0443
Research Progress of Vitamin D and Autoimmune Diseases
As a fat-soluble vitamin, Vitamin D is a necessary hormone to maintain normal physiological activities of the body. In recent years, vitamin D has been considered as a new neuroendocrine-immunomodulatory hormone, and researchers have paid more attention to the study of immune regulatory mechanism. It is not only related to calcium and phosphorus metabolism, bone metabolism and other important metabolic mechanisms of the body, but also closely related to the immune regulation mechanism of the body. Vitamin D deficiency caused by many factors can play a certain role in the development of autoimmune diseases. In this paper, the related mechanisms of vitamin D affecting autoimmune diseases were reviewed, with a view to expound the close correlation between vitamin D and autoimmune diseases, so as to find new diagnosis and treatment approaches for clinical autoimmune diseases and improve the quality of life of patients with autoimmune diseases
Design-while-verify
In the current control design of safety-critical cyber-physical systems, formal verification techniques are typically applied after the controller is designed to evaluate whether the required properties (e.g., safety) are satisfied. However, due to the increasing system complexity and the fundamental hardness of designing a controller with formal guarantees, such an open-loop process of design-then-verify often results in many iterations and fails to provide the necessary guarantees. In this paper, we propose a correct-by-construction control learning framework that integrates the verification into the control design process in a closed-loop manner, i.e., design-while-verify. Specifically, we leverage the verification results (computed reachable set of the system state) to construct feedback metrics for control learning, which measure how likely the current design of control parameters can meet the required reach-avoid property for safety and goal-reaching. We formulate an optimization problem based on such metrics for tuning the controller parameters, and develop an approximated gradient descent algorithm with a difference method to solve the optimization problem and learn the controller. The learned controller is formally guaranteed to meet the required reach-avoid property. By treating verifiability as a first-class objective and effectively leveraging the verification results during the control learning process, our approach can significantly improve the chance of finding a control design with formal property guarantees, demonstrated in a set of experiments that use model-based or neural network based controllers
Advances in Single Nucleotide Polymorphisms of Vitamin D Metabolic Pathway Genes and Respiratory Diseases
Vitamin D is a fat-soluble vitamin. It is an essential vitamin for human body. It has a classical effect on regulating calcium and phosphorus metabolism. Participate in cellular and humoral immune processes by regulating the growth, differentiation and metabolism of immune cells. A large number of studies in recent years have shown that vitamin D deficiency increases the incidence of respiratory diseases. Respiratory diseases mainly include bronchial asthma, chronic obstructive pulmonary disease, tuberculosis, acute upper respiratory tract infection and pneumonia. Vitamin D metabolic pathway genes play a very important regulatory role in the transformation of vitamin D into active vitamin D, including CYP2R1,,CYP27B1, CYP24A1, VDBP, VDR five genes. Genetic polymorphism of genes is the molecular basis of individual differences and disease development. Therefore, this paper summarizes the research on single nucleotide polymorphism of vitamin D metabolic pathway gene and respiratory diseases. In order to provide a new idea for future treatment
- …