66 research outputs found
The Application of Continuous Wavelet Transform Based Foreground Subtraction Method in 21 cm Sky Surveys
We propose a continuous wavelet transform based non-parametric foreground
subtraction method for the detection of redshifted 21 cm signal from the epoch
of reionization. This method works based on the assumption that the foreground
spectra are smooth in frequency domain, while the 21 cm signal spectrum is full
of saw-tooth-like structures, thus their characteristic scales are
significantly different. We can distinguish them in the wavelet coefficient
space easily and perform the foreground subtraction. Compared with the
traditional spectral fitting based method, our method is more tolerant to
complex foregrounds. Furthermore, we also find that when the instrument has
uncorrected response error, our method can also work significantly better than
the spectral fitting based method. Our method can obtain similar results with
the Wp smoothing method, which is also a non-parametric method, but our method
consumes much less computing time.Comment: Accepted by Ap
The Elderly Fall Detection Algorithm Based on Human Joint Extraction and Object Detection
Nowadays, the care of the elderly has become a social concern. The fall of the elderly has become one of the main factors threatening the health of the elderly. In this paper, we designed a fall detection algorithm based on human joint extraction and object detection.First,yolov4 was used to identify and detect the elderly. Then openpose was used to detect the human joint. Based on the human joint, this paper using Random Forest to classify the status of the elderly, there are three states of the elderly: falling down, lying down and other states. In the detection of a single old man, the accuracy of the model reached 99.3%, the sensitivity and specificity of the model reached 79.3% and 72.1%
Three-Layered Atmospheric Structure in Accretion Disks Around Stellar-Mass Black Holes
Modeling of the x-ray spectra of the Galactic superluminal jet sources GRS
1915+105 and GRO J1655-40 reveal a three-layered atmospheric structure in the
inner region of their accretion disks. Above the cold and optically thick disk
of a temperature 0.2-0.5 keV, there is a warm layer with a temperature of
1.0-1.5 keV and an optical depth around 10. Sometimes there is also a much
hotter, optically thin corona above the warm layer, with a temperature of 100
keV or higher and an optical depth around unity. The structural similarity
between the accretion disks and the solar atmosphere suggest that similar
physical processes may be operating in these different systems.Comment: 5 fives, 2 figures, 1 table. The online version of the paper in
Science may be accessed through http://jet.uah.edu/~zhangsn/papers.htm
Design of 60GHz Planar Array Antennas Using PCB-based Microstrip-Ridge Gap Waveguide and SIW
A wideband 2×2-slot element for a 60 GHz antenna array is designed by making use of two double-sided printed circuit boards (PCBs). The upper PCB contains the four radiating cavity-backed slots backed by a substrate-integrated waveguide (SIW) cavity. The SIW cavity is excited by a coupling slot fed by a microstrip-ridge gap waveguide formed in the air gap between the upper and lower PCBs. The designed 2×2-slot element is considered in an infinite array environment. A sample 32×32 slot array aperture is simulated using infinite array approach and the relative bandwidth of 16% over 57-66GHz frequency range with the directivity of more than 38 dBi over the operating bandwidth is obtained. The simulations are verified by measurements on a smaller 4×4 slot array surrounded by dummy elements
Circular RNA expression profiles in the porcine liver of two distinct phenotype pig breeds
Objective An experiment was conducted to identify and characterize the circular RNA expression and metabolic characteristics in the liver of Jinhua pigs and Landrace pigs. Methods Three Jinhua pigs and three Landrace pigs respectively at 70-day were slaughtered to collect the liver tissue samples. Immediately after slaughter, blood samples were taken to detect serum biochemical indicators. Total RNA extracted from liver tissue samples were used to prepare the library and then sequence on HiSeq 2500. Bioinformatic methods were employed to analyze sequence data to identify the circRNAs and predict the potential roles of differentially expressed circRNAs between the two breeds. Results Significant differences in physiological and biochemical traits were observed between growing Jinhua and Landrace pigs. We identified 84,864 circRNA candidates in two breeds and 366 circRNAs were detected as significantly differentially expressed. Their host genes are involved in lipid biosynthetic and metabolic processes according to the gene ontology analysis and associated with metabolic pathways. Conclusion Our research represents the first description of circRNA profiles in the porcine liver from two divergent phenotype pigs. The predicted miRNA-circRNA interaction provides important basis for miRNA-circRNA relationships in the porcine liver. These data expand the repertories of porcine circRNA and are conducive to understanding the possible molecular mechanisms involved in miRNA and circRNA. Our study provides basic data for further research of the biological functions of circRNAs in the porcine liver
A Search for X-Ray Reionization Signatures from Cross-Correlation of Wmap and ROSAT Rass Data
We present an observational search for the possible correlation between
cosmic microwave background (CMB) polarization map and soft X-ray background
(SXRB) based on the ROSAT All-sky Survey (RASS) archive and WMAP five-year
observations. This is motivated by the fact that some of the CMB polarization
may arise from the scattering of CMB photons due to the free electrons
generated by X-ray heating sources in the epoch of reionization. Detection of
such a correlation allows one to study the role of X-ray heating in the process
of reionization. However, the cross angular power spectrum of the CMB
polarization and SXRB maps constructed from ROSAT RASS and WMAP five-year maps
is consistent with no correlation. We attribute this negative detection to both
the extremely weak signals and large instrumental noises. While a future search
is needed with high sensitivity instruments for both CMB polarization and soft
X-ray photons, our current results can still be used as a useful constraint on
the effect of X-ray heating in the epoch of reionization.Comment: 17 Pages, 6 figure
A Joint Chandra and XMM-Newton View of Abell 3158: Massive Off-Centre Cool Gas Clump As A Robust Diagnostic of Merger Stage
By analysing the Chandra and XMM-Newton archived data of the nearby galaxy
cluster Abell 3158, which was reported to possess a relatively regular, relaxed
morphology in the X-ray band in previous works, we identify a bow edge-shaped
discontinuity in the X-ray surface brightness distribution at about
kpc west of the X-ray peak. This feature is found to be
associated with a massive, off-centre cool gas clump, and actually forms the
west boundary of the cool clump. We find that the cool gas clump is moving at a
subsonic velocity of ~700 km/s toward west on the sky plane. We exclude the
possibility that this cool clump was formed by local inhomogeneous radiative
cooling in the intra-cluster medium, due to the effectiveness of the thermal
conduction on the time-scale of Gyr. Since no evidence for central
AGN activity has been found in Abell 3158, and this cool clump bears many
similarities to the off-centre cool gas clumps detected in other merging
clusters in terms of their mass, size, location, and thermal properties (e.g.
lower temperature and higher abundance as compared with the environment), we
speculate that the cool clump in Abell 3158 was caused by a merger event, and
is the remnant of the original central cool-core of the main cluster or the
infalling sub-cluster. This idea is supported not only by the study of
line-of-sight velocity distribution of the cluster member galaxies, but also by
the study of gas entropy-temperature correlation. This example shows that the
appearance of such massive, off-centre cool gas clumps can be used to diagnose
the dynamical state of a cluster, especially when prominent shocks and cold
fronts are absent.Comment: Accepted by MNRAS; 12 pages, 6 figure
Towards Predicting Equilibrium Distributions for Molecular Systems with Deep Learning
Advances in deep learning have greatly improved structure prediction of
molecules. However, many macroscopic observations that are important for
real-world applications are not functions of a single molecular structure, but
rather determined from the equilibrium distribution of structures. Traditional
methods for obtaining these distributions, such as molecular dynamics
simulation, are computationally expensive and often intractable. In this paper,
we introduce a novel deep learning framework, called Distributional Graphormer
(DiG), in an attempt to predict the equilibrium distribution of molecular
systems. Inspired by the annealing process in thermodynamics, DiG employs deep
neural networks to transform a simple distribution towards the equilibrium
distribution, conditioned on a descriptor of a molecular system, such as a
chemical graph or a protein sequence. This framework enables efficient
generation of diverse conformations and provides estimations of state
densities. We demonstrate the performance of DiG on several molecular tasks,
including protein conformation sampling, ligand structure sampling,
catalyst-adsorbate sampling, and property-guided structure generation. DiG
presents a significant advancement in methodology for statistically
understanding molecular systems, opening up new research opportunities in
molecular science.Comment: 80 pages, 11 figure
Reconsidering the Barefoot Doctor Programme
This paper examines the widely acclaimed Barefoot Doctor campaign in China. The Barefoot Doctor Campaign has come to symbolize the success of Chinese health care to the extent that it has become a model for WHO public health strategy. Yet little has been done to understand how or whether it worked on the ground and what difficulties and contradictions emerged in its implementation. Using previously unexplored party archives as well as newly collected oral interviews, this paper moves away from a narrow focus on party politics and policy formulation by examining the reality of health care at the local level and the challenges faced by local authorities and individuals as the campaigns evolved
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