153 research outputs found
Genuine full characterization of partially coherence beam
For partially coherent light fields with random fluctuations, the intensity
distributions and statistics have been proven to be more propagation robust
compared with coherent light. However, its full potential in practical
applications has not been realized due to the lack of four-dimensional optical
field measurement. Here, a general modal decomposition method of partially
coherent light field is proposed and demonstrated. The decomposed random modes
can be used to, but not limited to, reconstruct average intensity, cross
spectral density and orthogonal decomposition properties of the partially
coherent light fields. Due to its versatility and flexibility, this method
provides a powerful tool to further reveal light field invariant or retrieve
embedded information after propagation through complex media. The
Gaussian-shell-model beam and partially coherent Gaussian array are used as
examples to demonstrate the reconstruction and even prediction of second-order
statistical characteristics. This method is expected to pave the way for
applications of partially coherent light in optical imaging, optical encryption
and anti-turblence optical communication
Plasma transferred arc surface alloying of Cr-Ni-Mo powders on compacted graphite iron
A Cr-Ni-Mo overlayer was deposited on the surface of compacted graphite iron (CGI) by the plasma transferred arc (PTA) alloying technique. The microstructure of Cr-Ni-Mo overlayer was characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and X-ray diffractometer (XRD). Results show that the cross-section consists of four regions: alloying zone (AZ), molten zone (MZ), heat affected zone (HAZ), and the substrate (SUB). The microstructure of AZ mainly consists of cellular γ-(Fe, Ni) solid solution, residual austenite and a network of eutectic Cr7C3 carbide while the MZ area has a typical feature of white cast iron (M3C-type cementite). The martensite/ledeburite double shells are observed in the HAZ. With decreasing the concentration of Cr-Ni-Mo alloys, the fracture mode changes from ductile in the AZ to brittle in the MZ. The maximum hardness of the AZ (450 HV0.2) is lower than that of the MZ (800 HV0.2). The eutectic M3C and M7C3 carbides increase the microhardness, while the austenite decreases that of the AZ
The fast light of CsI(Na) crystals
The responds of different common alkali halide crystals to alpha-rays and
gamma-rays are tested in our research. It is found that only CsI(Na) crystals
have significantly different waveforms between alpha and gamma scintillations,
while others have not this phenomena. It is suggested that the fast light of
CsI(Na) crystals arises from the recombination of free electrons with
self-trapped holes of the host crystal CsI. Self-absorption limits the emission
of fast light of CsI(Tl) and NaI(Tl) crystals.Comment: 5 pages, 11 figures Submit to Chinese Physics
Bulk-Switching Memristor-based Compute-In-Memory Module for Deep Neural Network Training
The need for deep neural network (DNN) models with higher performance and
better functionality leads to the proliferation of very large models. Model
training, however, requires intensive computation time and energy.
Memristor-based compute-in-memory (CIM) modules can perform vector-matrix
multiplication (VMM) in situ and in parallel, and have shown great promises in
DNN inference applications. However, CIM-based model training faces challenges
due to non-linear weight updates, device variations, and low-precision in
analog computing circuits. In this work, we experimentally implement a
mixed-precision training scheme to mitigate these effects using a
bulk-switching memristor CIM module. Lowprecision CIM modules are used to
accelerate the expensive VMM operations, with high precision weight updates
accumulated in digital units. Memristor devices are only changed when the
accumulated weight update value exceeds a pre-defined threshold. The proposed
scheme is implemented with a system-on-chip (SoC) of fully integrated analog
CIM modules and digital sub-systems, showing fast convergence of LeNet training
to 97.73%. The efficacy of training larger models is evaluated using realistic
hardware parameters and shows that that analog CIM modules can enable efficient
mix-precision DNN training with accuracy comparable to full-precision software
trained models. Additionally, models trained on chip are inherently robust to
hardware variations, allowing direct mapping to CIM inference chips without
additional re-training
Ethyl 5-[6-(furan-2-yl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazol-3-yl]-2,6-dimethylnicotinate
In the title compound, C17H15N5O3S, the plane of the triazolo–thiadiazole system forms dihedral angles of 15.68 and 4.46° with the planes of the pyridine and furan rings, respectively. In the molecule, there is an intramolecular C—H⋯N interaction. The crystal structure also contains other intermolecular interactions, such as C—H⋯O hydrogen bonds, π–π stacking (centroid–centroid distances = 3.746 and 3.444 Å), non-bonded S⋯N [3.026 (2) Å] and C—H⋯π interactions
Heavy Metals Pollution and Pb Isotopic Signatures in Surface Sediments Collected from Bohai Bay, North China
To investigate the characteristics and potential sources of heavy metals pollution, surface sediments collected from Bohai Bay, North China, were analyzed for the selected metals (Cd, Cr, Cu, Ni, Pb, and Zn). The Geoaccumulation Index was used to assess the level of heavy metal pollution. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were 0.15, 79.73, 28.70, 36.56, 25.63, and 72.83 mg/kg, respectively. The mean concentrations of the studied metals were slightly higher than the background values. However, the heavy metals concentrations in surface sediments in Bohai Bay were below the other important bays or estuaries in China. The assessment by Geoaccumulation Index indicated that Cr, Zn, and Cd were classified as “the unpolluted” level, while Ni, Cu, and Pb were ranked as “unpolluted to moderately polluted” level. The order of pollution level of heavy metals was: Pb>Ni>Cu>Cr>Zn>Cd. The Pb isotopic ratios in surface sediments varied from 1.159 to 1.185 for 206Pb/207Pb and from 2.456 to 2.482 for 208Pb/207Pb. Compared with Pb isotopic radios in other sources, Pb contaminations in the surface sediments of Bohai Bay may be controlled by the mix process of coal combustion, aerosol particles deposition, and natural sources
Evaluation of the reporting quality of clinical practice guidelines on gliomas using the RIGHT checklist
Background: The reporting quality of clinical practice guidelines (CPGs) for gliomas has not yet been thoroughly assessed. The International Reporting Items for Practice Guidelines in Healthcare (RIGHT) statement developed in 2016 provides a reporting framework to improve the quality of CPGs. We aimed to estimate the reporting quality of glioma guidelines using the RIGHT checklist and investigate how the reporting quality differs by selected characteristics. Methods: We systematically searched electronic databases, guideline databases, and medical society websites to retrieve CPGs on glioma published between 2018 and 2020. We calculated the compliance of the CPGs to individual items, domains and the RIGHT checklist overall. We performed stratified analyses by publication year, country of development, reporting of funding, and impact factor (IF) of the journal. Results: Our search revealed 20 eligible guidelines. Mean overall adherence to the RIGHT statement was 54.6%. Eight CPGs reported more than 60% of the items, and five reported less than 50%. All guidelines adhered to the items 1a, 3, 7a, 13a, while no guidelines reported the items 17 or 18b (see http://www.rightstatement.org/right-statement/checklist for a description of the items). Two of the seven domains, "Basic information" and "Background", had mean reporting rates above 60%. The "Review and quality assurance" domain had the lowest mean reporting rate, 12.5%. The reporting quality of guidelines published in 2020, guidelines developed in the United States, and guidelines that reported funding tended to be above average. Conclusions: The reporting quality of CPGs on gliomas is low and needs improvement. Particular attention should be paid on reporting the external review and quality assurance process. The use of the RIGHT criteria should be encouraged to guide the development, reporting and evaluation of CPGs
Study and Simulation of Deformation Mechanics Modeling of Flexible Workpiece Processing by Rayleigh-Ritz Method
This paper discusses the calculation problems of bending deformation of FWP processing. Take three axis CNC machining as an example, to establish mechanics model of flexible workpiece processing process. The flexible workpiece balance equation is a two-dimensional partial differential equation, to solve the problem of flexible workpiece bending deformation using Rayleigh-Ritz method and designing the test function of bending deformation of flexible workpiece. By satisfying the minimum potential energy condition of FWP processing to work out the approximate solution of bending deformation of flexible workpiece, find out the relationship between material properties of flexible piece, acting force Fz, and deformation value. Finally, the rectangle flexible workpiece which is made up of polyurethane sponge is selected as an experiment subject. The results show that the average relative deviation between theoretical value and observed value is only 5.51%. It is proved that the bending deformation test function satisfies the actual deformation calculation requirements
ZHENG-Omics Application in ZHENG Classification and Treatment: Chinese Personalized Medicine
With the hope to provide an effective approach for personalized diagnosis and treatment clinically, traditional chinese medicine (TCM) is being paid increasing attention as a complementary and alternative medicine. It performs treatment based on ZHENG (TCM syndrome) classification, which could be identified clinical special phenotypes by symptoms and signs of patients even if they have a different disease. However, it caused controversy because ZHENG classification only depends on observation, knowledge, and clinical experience of TCM practitioners, which lacks objectivity and repeatability. Although researchers and scientists of TCM have done some work with a lot of beneficial methods, the results could not reach satisfactory with the shortcomings of generalizing the entire state of the body or ignoring the patients' feelings. By total summary, mining, and integration of existing researches, the present paper attempts to introduce a novel macro-microconcept of ZHENG-omics, with the prospect of bright future in providing an objective and repeatable approach for Chinese personalized medicine in an effective way. In this paper, we give the brief introduction and preliminary validation, and discuss strategies and system-oriented technologies for achieving this goal
In vitro expression and analysis of the 826 human G protein-coupled receptors
ABSTRACT G protein-coupled receptors (GPCRs) are involved in all human physiological systems where they are responsible for transducing extracellular signals into cells. GPCRs signal in response to a diverse array of stimuli including light, hormones, and lipids, where these signals affect downstream cascades to impact both health and disease states. Yet, despite their importance as therapeutic targets, detailed molecular structures of only 30 GPCRs have been determined to date. A key challenge to their structure determination is adequate protein expression. Here we report the quantification of protein expression in an insect cell expression system for all 826 human GPCRs using two different fusion constructs. Expression characteristics are analyzed in aggregate and among each of the five distinct subfamilies. These data can be used to identify trends related to GPCR expression between different fusion constructs and between different GPCR families, and to prioritize lead candidates for future structure determination feasibility
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