Background::Acute type A aortic dissection(ATAAD)and acute type A intramural hematoma(ATAIMH)are life-threatening diseases with high mortality.To better understand their clinical features in the Chinese population,we ...Background::Acute type A aortic dissection(ATAAD)and acute type A intramural hematoma(ATAIMH)are life-threatening diseases with high mortality.To better understand their clinical features in the Chinese population,we analyzed the data from the first Registry of Aortic Dissection in China(Sino-RAD)to promote the understanding and management of the diseases.Methods::All patients with ATAAD and ATAIMH enrolled in Sino-RAD from January 1,2012 to December 31,2016 were involved.The data of patients’selection,history,symptoms,management,outcomes,and postoperation complications were analyzed in the study.The continuous variables were compared using the Student’s t test for normal distributions and the Mann-Whitney U test for non-normal distributions.Categorical variables were compared using the Chi-square test or Fisher exact test.Results::A total of 1582 patients with ATAAD and 130 patients with ATAIMH were included.The mean age of all patients was 48.4 years.Patients with ATAAD were significantly younger than patients with ATAIMH(48.9 years vs.55.6 years,P<0.001).For the total cohort,males were dominant,but the male ratio of patients with ATAAD was significantly higher compared to those with ATAIMH(P=0.01).The time range from the onset of symptom to hospitalization was 2.0 days.More patients of ATAIMH had hypertension than that of ATAAD(82.3%vs.67.6%,P<0.05).Chest and back pain were the most common clinical symptoms.Computerized tomography(CT)was the most common initial diagnostic imaging modality.84.7%received surgical treatment and in-hospital mortality was 5.3%.Patients with ATAAD mainly received surgical treatment(89.6%),while most patients with ATAIMH received medical treatment(39.2%)or endovascular repair(35.4%).Conclusions::Our study suggests that doctors should comprehensively use clinical examination and genetic background screening for patients with ATAAD and ATAIMH and further shorten the time range from symptoms onset to intervention,achieving early diagnosis and treatment,thereby reducing the mortality展开更多
Background： Safflower extract and aceglutamide （SA） has been used clinically for the treatment of cerebrovascular diseases such as cerebral embolism, hemorrhage, and mental deterioration. This study aimed to invest...Background： Safflower extract and aceglutamide （SA） has been used clinically for the treatment of cerebrovascular diseases such as cerebral embolism, hemorrhage, and mental deterioration. This study aimed to investigate the effect and mechanism of SA injection in the recovery of peripheral innervations of diabetic mice. Methods： The C57BL/6 male mice were divided into four groups： normal control group （n = 44）, diabetic group （n = 44）, diabetic ＋ SA group （diabetic mice treated with SA injection, n = 44）, and diabetic ＋ SA ＋ vascular endothelial growth factor receptor （VEGFR）1-BL group （diabetic mice treated with SA injection and VEGFR 1 blocking antibody n = 24）. The streptozotocin-induced diabetic mice model and injured peripheral nerve mice model were built. The mice with injured peripheral nerves were intraperitonealy administered with SA injection for successive 21 days. The corneal sensitivity, number of corneal nerve fibers, and contents of vascular endothelial growth factor （VEGF）-B and various neurotrophic factors such as nerve growth factor （NGF） and glial cell line-derived neurotrophic factor （GDNF） in corneal tissue of four groups were observed. Results： The diabetic group showed decreased number of corneal nerve fibers, compared with the control group （P = 0.002）. And compared with the diabetic group, the diabetic ＋ SA group showed a significant increase in the number of nerve fibers （P = 0.024） and the contents of VEGF-B,NGF,andGDNFinthecornea（allP〈0.05）.However,whenthediabeticmiceweretreatedwiththeblockingantibodiesspecializedfor VEGF-B receptor, the neutralization ofVEGFR-1 completely abolished the increased expression of NGF and GDNF stimulated by SAinjection. Conclusions： SA injection could reduce the nerve injury caused by diabetic peripheral neuropathy, and its protective effect might be associated with the promotion of the expressions of VEGF-B, NGF, and GDNF.展开更多
The electromagnetic radiation will result in informa- tion leakage being recovered when computers work. This article presents a high-speed real-time data acquisition system based on peripheral component interconnect ...The electromagnetic radiation will result in informa- tion leakage being recovered when computers work. This article presents a high-speed real-time data acquisition system based on peripheral component interconnect （PCI） bus and field programmable gate array （FPGA） for sampling electromagnetic radiation caused by video signal. The hardware design and controlling flow of each module are introduced in detail. The sampling rate can reach 64 Msps and system transfers speed can be up to 128 Mb/s by using time interleaving, which increases the overall sampling speed of a system by operating two data converters in parallel.展开更多
Stem cell therapy is a promising strategy for the treatment of traumatic brain injury(TBI). However, animal experiments are needed to evaluate safety;in particular, to examine the immunogenicity and tumorigenicity of ...Stem cell therapy is a promising strategy for the treatment of traumatic brain injury(TBI). However, animal experiments are needed to evaluate safety;in particular, to examine the immunogenicity and tumorigenicity of human umbilical cord mesenchymal stem cells(hu MSCs) before clinical application. In this study, hu MSCs were harvested from human amniotic membrane and umbilical cord vascular tissue. A rat model of TBI was established using the controlled cortical impact method. Starting from the third day after injury, the rats were injected with 10 μL of 5 × 10^(6)/m L hu MSCs by cerebral stereotaxis or with 500 μL of 1 × 10^(6)/m L hu MSCs via the tail vein for 3 successive days. hu MSC transplantation decreased the serum levels of proinflammatory cytokines in rats with TBI and increased the serum levels of anti-inflammatory cytokines, thereby exhibiting good immunoregulatory function. The transplanted hu MSCs were distributed in the liver, lung and brain injury sites. No abnormal proliferation or tumorigenesis was found in these organs up to 12 months after transplantation. The transplanted hu MSCs negligibly proliferated in vivo, and apoptosis was gradually observed at later stages. These findings suggest that hu MSC transplantation for the treatment of traumatic brain injury displays good safety. In addition, hu MSCs exhibit good immunoregulatory function, which can help prevent and reduce secondary brain injury caused by the rapid release of inflammatory factors after TBI. This study was approved by the Ethics Committee of Wuhan General Hospital of PLA(approval No. 20160054) on November 1, 2016.展开更多
In nature, many physical phenomena follow the least-action principle, which is also abided by the course of explosive welding of stainless steel/steel. The optimal welding interface can be obtained with the least expl...In nature, many physical phenomena follow the least-action principle, which is also abided by the course of explosive welding of stainless steel/steel. The optimal welding interface can be obtained with the least explosive charge by theoretical analysis and interface test. The bonding energy can be acknowledged as the ＂action＂ in explosive welding. To minimize the bonding energy, these rules must be followed such as the lower limit of explosive charge, the upper limit of span and the explosive of critical explosion velocity. The principle of least-action is achieved in the course of explosive welding, and the interface will be optimum.展开更多
In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights a...In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights and water depths. Numerical simulations are performed using a high-order finite-difference model solving Navier–Stokes (N–S) equations. The predicted water wave elevation, velocity and pressure show good agreement with experimental data, verifying the accuracy and capacity of the numerical model. Furthermore, parametric studies are conducted by numerical modelling to examine the effects of the geometrical features of submerged dike on hydrodynamic characteristics around the breakwater.展开更多
In recent years, Global Navigation Satellite Systems Reflectometry （GNSS-R） is developed to estimate soil moisture content （SMC） as a new remote sensing tool. Signal error of Global Positioning System （GPS） bist...In recent years, Global Navigation Satellite Systems Reflectometry （GNSS-R） is developed to estimate soil moisture content （SMC） as a new remote sensing tool. Signal error of Global Positioning System （GPS） bistatic radar is an important factor that affects the accuracy of SMC estimation. In this paper, two methods of GPS signal calibration involving both the direct and reflected signals are introduced, and a detailed explanation of the theoretical basis for such methods is given. An improved SMC estimation model utilizing calibrated GPS L-band signals is proposed, and the estimation accuracy is validated using the airborne GPS data from the Soil Moisture Experiment in 2002 （SMEX02）. We choose 21 sites with soybean and corn in the Walnut Creek region of the US for validation. The sites are divided into three categories according to their vegetation cover： bare soil, mid-vegetation cover （Mid-Veg）, and high-vegetation cover （High-Veg）. The accuracy of SMC estimation .is 11.17% for bare soil and 8.12% for Mid-Veg sites, much better than that of the traditional model. For High-Veg sites, the effect of signal attenuation due to vegetation cover is preliminarily taken into consideration and a linear model related to Normalized Difference Vegetation Indices （NDVI） is adopted to obtain a factor for rectifying the ＂over-calibration＂, and the error for High-Veg sites is finally reduced to 3.81%.展开更多
This study uses the WRF-Chem model combined with the empirical kinetic modeling method(EKMA curve)to study the compound pollution event in Beijing that happened in 13−23 May 2017.Sensitivity tests are conducted to ana...This study uses the WRF-Chem model combined with the empirical kinetic modeling method(EKMA curve)to study the compound pollution event in Beijing that happened in 13−23 May 2017.Sensitivity tests are conducted to analyze ozone sensitivity to its precursors,and to develop emission reduction measures.The results suggest that the model can accurately simulate the compound pollution process of photochemistry and haze.When VOCs and NOx were reduced by the same proportion,the effect of O_(3)reduction at peak time was more obvious,and the effect during daytime was more significant than at night.The degree of change in ozone was peak time>daytime average.When reducing or increasing the ratio of precursors by 25%at the same time,the effect of reducing 25%VOCs on the average ozone concentration reduction was most significant.The degree of change in ozone decreased with increasing altitude,the location of the ozone maximum change shifted westward,and its range narrowed.As the altitude increases,the VOCs-limited zone decreases,VOCs sensitivity decreases,NOx sensitivity increases.The controlled area changed from near-surface VOCs-limited to high-altitude NOx-limited.Upon examining the EKMA curve,we have found that suburban and urban are sensitive to VOCs.The sensitivity tests indicate that when VOCs in suburban are reduced about 60%,the O_(3)-1h concentration could reach the standard,and when VOCs of the urban decreased by about 50%,the O_(3)-1h concentration could reach the standard.Thus,these findings could provide references for the control of compound air pollution in Beijing.展开更多
The unsupervised multi-modal image translation is an emerging domain of computer vision whose goal is to transform an image from the source domain into many diverse styles in the target domain.However,the multi-genera...The unsupervised multi-modal image translation is an emerging domain of computer vision whose goal is to transform an image from the source domain into many diverse styles in the target domain.However,the multi-generator mechanism is employed among the advanced approaches available to model different domain mappings,which results in inefficient training of neural networks and pattern collapse,leading to inefficient generation of image diversity.To address this issue,this paper introduces a multi-modal unsupervised image translation framework that uses a generator to perform multi-modal image translation.Specifically,firstly,the domain code is introduced in this paper to explicitly control the different generation tasks.Secondly,this paper brings in the squeeze-and-excitation(SE)mechanism and feature attention(FA)module.Finally,the model integrates multiple optimization objectives to ensure efficient multi-modal translation.This paper performs qualitative and quantitative experiments on multiple non-paired benchmark image translation datasets while demonstrating the benefits of the proposed method over existing technologies.Overall,experimental results have shown that the proposed method is versatile and scalable.展开更多
The increasingly severe electromagnetic microwave pollution raises higher requirements for the development of efficient microwave absorption(MA)materials.Metal sulfides are regarded as potential robust MA materials be...The increasingly severe electromagnetic microwave pollution raises higher requirements for the development of efficient microwave absorption(MA)materials.Metal sulfides are regarded as potential robust MA materials because of their unique optical,thermal,electrical,and magnetic properties,as well as the controllable microstructures.However,due to the limited MA performances of unary metal sulfides,morphology regulations and foreign materials hybridizations are adopted as effective strategies to improve their MA performances.Recent years witnessed the fast research progresses on the metal sulfides based MA materials and thus,a systematic literature survey on the materials design,fabrication,characterizations,MA behaviors,and the mechanisms behind is,highly desirable to summarize the rapid progress of this hot research area so as to provide guidance for the future development trend.This review firstly reviewed the research background,research progress,and basic principles of MA materials.Subsequently,the present synthetic methods and performance improvement strategies of metal sulfides based MA materials are systematically introduced.Then,by comparing the MA properties of one-dimensional,two-dimensional,and three-dimensional metal sulfides based composites,the influence of dimensionality and morphology on the MA properties are analyzed.By summarizing the research process of metal sulfides/dielectrics composites,metal sulfides/magnets composites,and metal sulfides/dielectrics/magnets composites MA materials,the influence of foreign materials hybridizations on the loss mechanisms and impedance matching conditions of metal sulfides based composites are revealed.Finally,the challenges and development prospects of metal sulfides based MA materials are presented.This review would provide a comprehensive understanding and insightful guidance for the exploration and development of efficient MA materials with thin thickness,light weight,wide absorption bandwidth,and strong absorption intensity.展开更多
Tribological characteristics and self-repairing effect of hydroxy-magnesium silicate (HMS) dispersed in lubricant oil on steel-to-steel friction pairs with various surface roughness were analyzed.The friction-reductio...Tribological characteristics and self-repairing effect of hydroxy-magnesium silicate (HMS) dispersed in lubricant oil on steel-to-steel friction pairs with various surface roughness were analyzed.The friction-reduction,anti-wear and self-repairing performance of various surface roughness friction pairs were examined by friction testing machine.An operation comparison was made between SJ10W-40 lubricant with and without HMS.The surface morphology and elementary composition of the grinding cracks were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The results show that the lubrication state changes from boundary lubrication into mixed lubrication after operation in lubricant with HMS.The friction-reduction,anti-wear and self-repairing performance of the friction pairs with various surface roughness are distinctly different.There is a repairing film whose material is different from substrate material on the grinding cracks.In addition,Si,Mg,O,Al and other elements are deposited on the repairing film which contains nanocrystals of these elements.And HMS self-repairing material possesses superior performance of friction-reduction,anti-wear and self-repairing effects.展开更多
The joint optimization of detection threshold and waveform parameters for target tracking which comes from the idea of cognitive radar is investigated for the modified probabilistic data association(MPDA)filter.The tr...The joint optimization of detection threshold and waveform parameters for target tracking which comes from the idea of cognitive radar is investigated for the modified probabilistic data association(MPDA)filter.The transmitted waveforms and detection threshold are adaptively selected to enhance the tracking performance.The modified Riccati equation is adopted to predict the error covariance which is used as the criterion function,while the optimization problem is solved through the genetic algorithm(GA).The detection probability,false alarm probability and measurement noise covariance are all considered together,which significantly improves the tracking performance of the joint detection and tracking system.Simulation results show that the proposed adaptive waveform-detection threshold joint optimization method outperforms the adaptive threshold method and the fixed parameters method,which will reduce the tracking error.The average reduction of range error between the adaptive joint method and the fixed parameters method is about 0.6 m,while that between the adaptive joint method and the adaptive threshold only method is about 0.3 m.Similar error reduction occurs for the velocity error and acceleration error.展开更多
In this paper,based on a bidirectional parallel multi-branch feature pyramid network(BPMFPN),a novel one-stage object detector called BPMFPN Det is proposed for real-time detection of ground multi-scale targets by swa...In this paper,based on a bidirectional parallel multi-branch feature pyramid network(BPMFPN),a novel one-stage object detector called BPMFPN Det is proposed for real-time detection of ground multi-scale targets by swarm unmanned aerial vehicles(UAVs).First,the bidirectional parallel multi-branch convolution modules are used to construct the feature pyramid to enhance the feature expression abilities of different scale feature layers.Next,the feature pyramid is integrated into the single-stage object detection framework to ensure real-time performance.In order to validate the effectiveness of the proposed algorithm,experiments are conducted on four datasets.For the PASCAL VOC dataset,the proposed algorithm achieves the mean average precision(mAP)of 85.4 on the VOC 2007 test set.With regard to the detection in optical remote sensing(DIOR)dataset,the proposed algorithm achieves 73.9 mAP.For vehicle detection in aerial imagery(VEDAI)dataset,the detection accuracy of small land vehicle(slv)targets reaches 97.4 mAP.For unmanned aerial vehicle detection and tracking(UAVDT)dataset,the proposed BPMFPN Det achieves the mAP of 48.75.Compared with the previous state-of-the-art methods,the results obtained by the proposed algorithm are more competitive.The experimental results demonstrate that the proposed algorithm can effectively solve the problem of real-time detection of ground multi-scale targets in aerial images of swarm UAVs.展开更多
The characteristic changes of South Pacific sea surface temperature anomalies （SSTAs） for the period January 1979 to December 2011, during which the 1990s Pacific pan-decadal variability （PDV） interdecadal regime ...The characteristic changes of South Pacific sea surface temperature anomalies （SSTAs） for the period January 1979 to December 2011, during which the 1990s Pacific pan-decadal variability （PDV） interdecadal regime shifts occurred, were examined. Empirical Orthogonal Function （EOF） analysis was applied to the monthly mean SSTA for two sub-periods： January 1979 to December 1994 （P 1） and January 1996 to December 2011 （P2）. Both the spatial and temporal features of the leading EOF mode for P1 and P2 showed a remarkable difference. The spatial structure of the leading EOF changed from a tripolar pattern for P 1 （EOF-P 1） to a dipole-like pattern for P2 （EOF-P2）. Besides, EOF-P 1 （EOF-P2） had significant spectral peaks at 4.6 yr （2.7 yr）. EOF-P2 not only had a closer association with E1 Nifio-Southern Oscillation （ENSO）, but also showed a faster response to ENSO than EOF-P1 based on their lead-lag relationships with ENSO. During the development of ENSO, the South Pacific SSTA associated with ENSO for both PI and P2 showed a significant eastward propagation. However, after the peak of ENSO, EOF-P1 showed a stronger persistence than EOF-P2, which still showed eastward propagation. The variability of the SSTA associated with the whole process of ENSO evolution during P1 and the SSTA associated with the development of ENSO during P2 support the existence of ocean-to-atmosphere forcing, but the SSTA associated with the decay of ENSO shows the phenomenon of atmosphere-to-ocean forcing.展开更多
In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc...In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc networks is proposed.In this scheme, a sender can simultaneously signcrypt n messeges for n receivers, and a receiver can unsigncrypt the ciphertext to get his message with his own private key.An analysis of this scheme indicates that it achieves authenticity and confidentiality in the random oracle model while being of lower computation and communication overhead.Finally, for the application of our scheme in ad hoc, a threshold key updating protocol for ad hoc networks is given.展开更多
One-dimensional detonation model and two-dimensional P-M （Prandtl-Meyer） expanding model of double vertical explosive welding were established. A one-dimensional formula of flyer plate velocity was obtained and the ...One-dimensional detonation model and two-dimensional P-M （Prandtl-Meyer） expanding model of double vertical explosive welding were established. A one-dimensional formula of flyer plate velocity was obtained and the bending angle curve representing flying attitude of flyer plate in double vertical was deduced as well. Compared with single parallel explosive welding, the double vertical explosive welding combines two cladding plates in one explosion. Due to closed charging structure, the influence of rarefaction wave on the plate＇s surface in double vertical explosive welding is eliminated and explosion loading time and displacement are increased, resulting in the increase of flyer velocity and energy utilization rate by 1.3 times to 1.6 times in different mass ratios. The analysis of microstructure in bonding zone of double vertical cladding plate under traditional charging shows that there is a clear over-melting near the interface, which is in line with the conclusion of detonation mechanism.展开更多
The rip currents induced by waves off arc-shaped coastlines are seriously harmful to humans, but understanding of their characteristics is lacking. In this study, the FUNWAVE model was used to calculate the wave-induc...The rip currents induced by waves off arc-shaped coastlines are seriously harmful to humans, but understanding of their characteristics is lacking. In this study, the FUNWAVE model was used to calculate the wave-induced currents in the Haller experiment and the ideal arc-shaped coast similar to Sanya Dadonghai, Hainan Province,China. The results showed that the FUNWAVE model has considerable ability to simulate the rip currents, and it was used to further simulate rip currents off arc-shaped coastlines to investigate their characteristics. The rip currents were found to be stronger as the curvature of arc-shaped coastline increased. Coastal beach slope exerts a significant influence on rip currents; in particular, an overly steep or overly mild slope is not conducive to creating rip currents. Furthermore, the rip currents were found to become weaker as the size of arc-shaped coast decreased. When the height and period of waves increase, the strength of rip currents also increases, and, in some cases, wave heights of 0.4 m may produce dangerous rip currents.展开更多
In nonlinear error growth dynamics,the initial error cannot be accurately determined,and the forecast error,which is also uncertain,can be considered to be a random variable.Entropy in information theory is a natural ...In nonlinear error growth dynamics,the initial error cannot be accurately determined,and the forecast error,which is also uncertain,can be considered to be a random variable.Entropy in information theory is a natural measure of the uncertainty of a random variable associated with a probability distribution.This paper effectively combines statistical information theory and nonlinear error growth dynamics,and introduces some fundamental concepts of entropy in information theory for nonlinear error growth dynamics.Entropy based on nonlinear error can be divided into time entropy and space entropy,which are used to estimate the predictabilities of the whole dynamical system and each of its variables.This is not only applicable for investigating the dependence between any two variables of a multivariable system,but also for measuring the influence of each variable on the predictability of the whole system.Taking the Lorenz system as an example,the entropy of nonlinear error is applied to estimate predictability.The time and space entropies are used to investigate the spatial distribution of predictability of the whole Lorenz system.The results show that when moving around two chaotic attractors or near the edge of system space,a Lorenz system with lower sensitivity to the initial field behaves with higher predictability and a longer predictability limit.The example analysis of predictability of the Lorenz system demonstrates that the predictability estimated by the entropy of nonlinear error is feasible and effective,especially for estimation of predictability of the whole system.This provides a theoretical foundation for further work in estimating real atmospheric multivariable joint predictability.展开更多
Formamidinium lead halide(α-FAPbI3)with a broad light absorption spectrum,has recently received considerable attention in optoelectronic applications.However,the FAI-PbI2-DMSO(DMSO:dimethyl sulfoxide)intermediate ani...Formamidinium lead halide(α-FAPbI3)with a broad light absorption spectrum,has recently received considerable attention in optoelectronic applications.However,the FAI-PbI2-DMSO(DMSO:dimethyl sulfoxide)intermediate anisotropic fibers readily form a non-perovskite phase(δ-FAPbI3)and uncontrolled excess PbI2,which hinders the further increase in the efficiencies of solar cells.Caculations indicate that iodine defects in polycrystalline films would enlarge the perovskite tolerance factor and result in the formation of iodide Frenkel defects.Herein,we introduce a post-treatment technique to heal the as-prepared FAPbI3 thin layer and restrain the notoriousδ-FAPbI3 through vacancy filling.Furthermore,a new intermediate phase of FAI-PbI2-DMSO-FACl led to a high-quality perovskite layer with an enlarged average grain size that exceeded 2μm.Consequently,the power conversion efficiencies of FAPbI3 solar cells were significantly enhanced due to the high crystallity of the pureα-phase perovskite.Therefore,this method can be used to obtain high pure-black perovskite films and efficient solar cells.展开更多
基金the National Key Research and Development Program of China(2016YFC1301900)the National Natural Science Foundation of China(81970213,81870218,and 81770373)the Subject Booster Program from Xijing Hospital,the Fourth Military Medical University(XJZT18M L13).
文摘Background::Acute type A aortic dissection(ATAAD)and acute type A intramural hematoma(ATAIMH)are life-threatening diseases with high mortality.To better understand their clinical features in the Chinese population,we analyzed the data from the first Registry of Aortic Dissection in China(Sino-RAD)to promote the understanding and management of the diseases.Methods::All patients with ATAAD and ATAIMH enrolled in Sino-RAD from January 1,2012 to December 31,2016 were involved.The data of patients’selection,history,symptoms,management,outcomes,and postoperation complications were analyzed in the study.The continuous variables were compared using the Student’s t test for normal distributions and the Mann-Whitney U test for non-normal distributions.Categorical variables were compared using the Chi-square test or Fisher exact test.Results::A total of 1582 patients with ATAAD and 130 patients with ATAIMH were included.The mean age of all patients was 48.4 years.Patients with ATAAD were significantly younger than patients with ATAIMH(48.9 years vs.55.6 years,P<0.001).For the total cohort,males were dominant,but the male ratio of patients with ATAAD was significantly higher compared to those with ATAIMH(P=0.01).The time range from the onset of symptom to hospitalization was 2.0 days.More patients of ATAIMH had hypertension than that of ATAAD(82.3%vs.67.6%,P<0.05).Chest and back pain were the most common clinical symptoms.Computerized tomography(CT)was the most common initial diagnostic imaging modality.84.7%received surgical treatment and in-hospital mortality was 5.3%.Patients with ATAAD mainly received surgical treatment(89.6%),while most patients with ATAIMH received medical treatment(39.2%)or endovascular repair(35.4%).Conclusions::Our study suggests that doctors should comprehensively use clinical examination and genetic background screening for patients with ATAAD and ATAIMH and further shorten the time range from symptoms onset to intervention,achieving early diagnosis and treatment,thereby reducing the mortality
基金This study was supported by grants from Shandong Provincial Natural Science Foundation, China （No. ZR2016HPI 7）, the Project of Medical and Health Technology Development Program in Shandong Province （No. 2016WS0282）, and Qingdao Postdoctoral Application Research Funded Project （No. 2016063）.
文摘Background： Safflower extract and aceglutamide （SA） has been used clinically for the treatment of cerebrovascular diseases such as cerebral embolism, hemorrhage, and mental deterioration. This study aimed to investigate the effect and mechanism of SA injection in the recovery of peripheral innervations of diabetic mice. Methods： The C57BL/6 male mice were divided into four groups： normal control group （n = 44）, diabetic group （n = 44）, diabetic ＋ SA group （diabetic mice treated with SA injection, n = 44）, and diabetic ＋ SA ＋ vascular endothelial growth factor receptor （VEGFR）1-BL group （diabetic mice treated with SA injection and VEGFR 1 blocking antibody n = 24）. The streptozotocin-induced diabetic mice model and injured peripheral nerve mice model were built. The mice with injured peripheral nerves were intraperitonealy administered with SA injection for successive 21 days. The corneal sensitivity, number of corneal nerve fibers, and contents of vascular endothelial growth factor （VEGF）-B and various neurotrophic factors such as nerve growth factor （NGF） and glial cell line-derived neurotrophic factor （GDNF） in corneal tissue of four groups were observed. Results： The diabetic group showed decreased number of corneal nerve fibers, compared with the control group （P = 0.002）. And compared with the diabetic group, the diabetic ＋ SA group showed a significant increase in the number of nerve fibers （P = 0.024） and the contents of VEGF-B,NGF,andGDNFinthecornea（allP〈0.05）.However,whenthediabeticmiceweretreatedwiththeblockingantibodiesspecializedfor VEGF-B receptor, the neutralization ofVEGFR-1 completely abolished the increased expression of NGF and GDNF stimulated by SAinjection. Conclusions： SA injection could reduce the nerve injury caused by diabetic peripheral neuropathy, and its protective effect might be associated with the promotion of the expressions of VEGF-B, NGF, and GDNF.
基金the National Natural Science Foundation of China （60331010, 60271018）.
文摘The electromagnetic radiation will result in informa- tion leakage being recovered when computers work. This article presents a high-speed real-time data acquisition system based on peripheral component interconnect （PCI） bus and field programmable gate array （FPGA） for sampling electromagnetic radiation caused by video signal. The hardware design and controlling flow of each module are introduced in detail. The sampling rate can reach 64 Msps and system transfers speed can be up to 128 Mb/s by using time interleaving, which increases the overall sampling speed of a system by operating two data converters in parallel.
基金supported by the General Project of Hubei Health Committee of China,No.WJ2019M263(to GW)。
文摘Stem cell therapy is a promising strategy for the treatment of traumatic brain injury(TBI). However, animal experiments are needed to evaluate safety;in particular, to examine the immunogenicity and tumorigenicity of human umbilical cord mesenchymal stem cells(hu MSCs) before clinical application. In this study, hu MSCs were harvested from human amniotic membrane and umbilical cord vascular tissue. A rat model of TBI was established using the controlled cortical impact method. Starting from the third day after injury, the rats were injected with 10 μL of 5 × 10^(6)/m L hu MSCs by cerebral stereotaxis or with 500 μL of 1 × 10^(6)/m L hu MSCs via the tail vein for 3 successive days. hu MSC transplantation decreased the serum levels of proinflammatory cytokines in rats with TBI and increased the serum levels of anti-inflammatory cytokines, thereby exhibiting good immunoregulatory function. The transplanted hu MSCs were distributed in the liver, lung and brain injury sites. No abnormal proliferation or tumorigenesis was found in these organs up to 12 months after transplantation. The transplanted hu MSCs negligibly proliferated in vivo, and apoptosis was gradually observed at later stages. These findings suggest that hu MSC transplantation for the treatment of traumatic brain injury displays good safety. In addition, hu MSCs exhibit good immunoregulatory function, which can help prevent and reduce secondary brain injury caused by the rapid release of inflammatory factors after TBI. This study was approved by the Ethics Committee of Wuhan General Hospital of PLA(approval No. 20160054) on November 1, 2016.
基金Sponsored by Jiangsu Provincial Foundation of Technology Achievement Transform of China(BA2012030)
文摘In nature, many physical phenomena follow the least-action principle, which is also abided by the course of explosive welding of stainless steel/steel. The optimal welding interface can be obtained with the least explosive charge by theoretical analysis and interface test. The bonding energy can be acknowledged as the ＂action＂ in explosive welding. To minimize the bonding energy, these rules must be followed such as the lower limit of explosive charge, the upper limit of span and the explosive of critical explosion velocity. The principle of least-action is achieved in the course of explosive welding, and the interface will be optimum.
基金financially supported by the National Natural Science Foundation of China(Grant No.51679212)Zhejiang Provincial Natural Science Foundation of China(Grant No.LR16E090002)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2018QNA4041)the Tang Scholar
文摘In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights and water depths. Numerical simulations are performed using a high-order finite-difference model solving Navier–Stokes (N–S) equations. The predicted water wave elevation, velocity and pressure show good agreement with experimental data, verifying the accuracy and capacity of the numerical model. Furthermore, parametric studies are conducted by numerical modelling to examine the effects of the geometrical features of submerged dike on hydrodynamic characteristics around the breakwater.
基金Supported by the National "12th Five-Year Plan" Pre-Research Program on Civil Space
文摘In recent years, Global Navigation Satellite Systems Reflectometry （GNSS-R） is developed to estimate soil moisture content （SMC） as a new remote sensing tool. Signal error of Global Positioning System （GPS） bistatic radar is an important factor that affects the accuracy of SMC estimation. In this paper, two methods of GPS signal calibration involving both the direct and reflected signals are introduced, and a detailed explanation of the theoretical basis for such methods is given. An improved SMC estimation model utilizing calibrated GPS L-band signals is proposed, and the estimation accuracy is validated using the airborne GPS data from the Soil Moisture Experiment in 2002 （SMEX02）. We choose 21 sites with soybean and corn in the Walnut Creek region of the US for validation. The sites are divided into three categories according to their vegetation cover： bare soil, mid-vegetation cover （Mid-Veg）, and high-vegetation cover （High-Veg）. The accuracy of SMC estimation .is 11.17% for bare soil and 8.12% for Mid-Veg sites, much better than that of the traditional model. For High-Veg sites, the effect of signal attenuation due to vegetation cover is preliminarily taken into consideration and a linear model related to Normalized Difference Vegetation Indices （NDVI） is adopted to obtain a factor for rectifying the ＂over-calibration＂, and the error for High-Veg sites is finally reduced to 3.81%.
基金This study is funded by Air Pollution Special Project of the Ministry of Science and Technology(Grant No.2017YFCOZ10006)the National Natural Science Foundation of China(Grant No.41975173)。
文摘This study uses the WRF-Chem model combined with the empirical kinetic modeling method(EKMA curve)to study the compound pollution event in Beijing that happened in 13−23 May 2017.Sensitivity tests are conducted to analyze ozone sensitivity to its precursors,and to develop emission reduction measures.The results suggest that the model can accurately simulate the compound pollution process of photochemistry and haze.When VOCs and NOx were reduced by the same proportion,the effect of O_(3)reduction at peak time was more obvious,and the effect during daytime was more significant than at night.The degree of change in ozone was peak time>daytime average.When reducing or increasing the ratio of precursors by 25%at the same time,the effect of reducing 25%VOCs on the average ozone concentration reduction was most significant.The degree of change in ozone decreased with increasing altitude,the location of the ozone maximum change shifted westward,and its range narrowed.As the altitude increases,the VOCs-limited zone decreases,VOCs sensitivity decreases,NOx sensitivity increases.The controlled area changed from near-surface VOCs-limited to high-altitude NOx-limited.Upon examining the EKMA curve,we have found that suburban and urban are sensitive to VOCs.The sensitivity tests indicate that when VOCs in suburban are reduced about 60%,the O_(3)-1h concentration could reach the standard,and when VOCs of the urban decreased by about 50%,the O_(3)-1h concentration could reach the standard.Thus,these findings could provide references for the control of compound air pollution in Beijing.
基金the National Natural Science Foundation of China(No.61976080)the Academic Degrees&Graduate Education Reform Project of Henan Province(No.2021SJGLX195Y)+1 种基金the Teaching Reform Research and Practice Project of Henan Undergraduate Universities(No.2022SYJXLX008)the Key Project on Research and Practice of Henan University Graduate Education and Teaching Reform(No.YJSJG2023XJ006)。
文摘The unsupervised multi-modal image translation is an emerging domain of computer vision whose goal is to transform an image from the source domain into many diverse styles in the target domain.However,the multi-generator mechanism is employed among the advanced approaches available to model different domain mappings,which results in inefficient training of neural networks and pattern collapse,leading to inefficient generation of image diversity.To address this issue,this paper introduces a multi-modal unsupervised image translation framework that uses a generator to perform multi-modal image translation.Specifically,firstly,the domain code is introduced in this paper to explicitly control the different generation tasks.Secondly,this paper brings in the squeeze-and-excitation(SE)mechanism and feature attention(FA)module.Finally,the model integrates multiple optimization objectives to ensure efficient multi-modal translation.This paper performs qualitative and quantitative experiments on multiple non-paired benchmark image translation datasets while demonstrating the benefits of the proposed method over existing technologies.Overall,experimental results have shown that the proposed method is versatile and scalable.
基金financially supported by the National Natural Science Foundation of China(Nos.51572157,21902085 and 51702188)Natural Science Foundation of Shandong Province(No.ZR2019QF012)+1 种基金Fundamental Research Funds for the Central Universities(Nos.2018JC036 and 2018JC046)Shandong Key Research and Development Program(No.2019JZZY010312)。
文摘The increasingly severe electromagnetic microwave pollution raises higher requirements for the development of efficient microwave absorption(MA)materials.Metal sulfides are regarded as potential robust MA materials because of their unique optical,thermal,electrical,and magnetic properties,as well as the controllable microstructures.However,due to the limited MA performances of unary metal sulfides,morphology regulations and foreign materials hybridizations are adopted as effective strategies to improve their MA performances.Recent years witnessed the fast research progresses on the metal sulfides based MA materials and thus,a systematic literature survey on the materials design,fabrication,characterizations,MA behaviors,and the mechanisms behind is,highly desirable to summarize the rapid progress of this hot research area so as to provide guidance for the future development trend.This review firstly reviewed the research background,research progress,and basic principles of MA materials.Subsequently,the present synthetic methods and performance improvement strategies of metal sulfides based MA materials are systematically introduced.Then,by comparing the MA properties of one-dimensional,two-dimensional,and three-dimensional metal sulfides based composites,the influence of dimensionality and morphology on the MA properties are analyzed.By summarizing the research process of metal sulfides/dielectrics composites,metal sulfides/magnets composites,and metal sulfides/dielectrics/magnets composites MA materials,the influence of foreign materials hybridizations on the loss mechanisms and impedance matching conditions of metal sulfides based composites are revealed.Finally,the challenges and development prospects of metal sulfides based MA materials are presented.This review would provide a comprehensive understanding and insightful guidance for the exploration and development of efficient MA materials with thin thickness,light weight,wide absorption bandwidth,and strong absorption intensity.
基金Projects(50735006,50904072) supported by the National Natural Science Foundation of ChinaProject(2007CB607601) supported by the National Basic Research Program of China
文摘Tribological characteristics and self-repairing effect of hydroxy-magnesium silicate (HMS) dispersed in lubricant oil on steel-to-steel friction pairs with various surface roughness were analyzed.The friction-reduction,anti-wear and self-repairing performance of various surface roughness friction pairs were examined by friction testing machine.An operation comparison was made between SJ10W-40 lubricant with and without HMS.The surface morphology and elementary composition of the grinding cracks were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The results show that the lubrication state changes from boundary lubrication into mixed lubrication after operation in lubricant with HMS.The friction-reduction,anti-wear and self-repairing performance of the friction pairs with various surface roughness are distinctly different.There is a repairing film whose material is different from substrate material on the grinding cracks.In addition,Si,Mg,O,Al and other elements are deposited on the repairing film which contains nanocrystals of these elements.And HMS self-repairing material possesses superior performance of friction-reduction,anti-wear and self-repairing effects.
基金Project(61171133) supported by the National Natural Science Foundation of ChinaProject(11JJ1010) supported by the Natural Science Fund for Distinguished Young Scholars of Hunan Province,China
文摘The joint optimization of detection threshold and waveform parameters for target tracking which comes from the idea of cognitive radar is investigated for the modified probabilistic data association(MPDA)filter.The transmitted waveforms and detection threshold are adaptively selected to enhance the tracking performance.The modified Riccati equation is adopted to predict the error covariance which is used as the criterion function,while the optimization problem is solved through the genetic algorithm(GA).The detection probability,false alarm probability and measurement noise covariance are all considered together,which significantly improves the tracking performance of the joint detection and tracking system.Simulation results show that the proposed adaptive waveform-detection threshold joint optimization method outperforms the adaptive threshold method and the fixed parameters method,which will reduce the tracking error.The average reduction of range error between the adaptive joint method and the fixed parameters method is about 0.6 m,while that between the adaptive joint method and the adaptive threshold only method is about 0.3 m.Similar error reduction occurs for the velocity error and acceleration error.
文摘In this paper,based on a bidirectional parallel multi-branch feature pyramid network(BPMFPN),a novel one-stage object detector called BPMFPN Det is proposed for real-time detection of ground multi-scale targets by swarm unmanned aerial vehicles(UAVs).First,the bidirectional parallel multi-branch convolution modules are used to construct the feature pyramid to enhance the feature expression abilities of different scale feature layers.Next,the feature pyramid is integrated into the single-stage object detection framework to ensure real-time performance.In order to validate the effectiveness of the proposed algorithm,experiments are conducted on four datasets.For the PASCAL VOC dataset,the proposed algorithm achieves the mean average precision(mAP)of 85.4 on the VOC 2007 test set.With regard to the detection in optical remote sensing(DIOR)dataset,the proposed algorithm achieves 73.9 mAP.For vehicle detection in aerial imagery(VEDAI)dataset,the detection accuracy of small land vehicle(slv)targets reaches 97.4 mAP.For unmanned aerial vehicle detection and tracking(UAVDT)dataset,the proposed BPMFPN Det achieves the mAP of 48.75.Compared with the previous state-of-the-art methods,the results obtained by the proposed algorithm are more competitive.The experimental results demonstrate that the proposed algorithm can effectively solve the problem of real-time detection of ground multi-scale targets in aerial images of swarm UAVs.
基金supported by the National Basic Research Program of China(Grant Nos.2010CB950400 and 2013CB956203)
文摘The characteristic changes of South Pacific sea surface temperature anomalies （SSTAs） for the period January 1979 to December 2011, during which the 1990s Pacific pan-decadal variability （PDV） interdecadal regime shifts occurred, were examined. Empirical Orthogonal Function （EOF） analysis was applied to the monthly mean SSTA for two sub-periods： January 1979 to December 1994 （P 1） and January 1996 to December 2011 （P2）. Both the spatial and temporal features of the leading EOF mode for P1 and P2 showed a remarkable difference. The spatial structure of the leading EOF changed from a tripolar pattern for P 1 （EOF-P 1） to a dipole-like pattern for P2 （EOF-P2）. Besides, EOF-P 1 （EOF-P2） had significant spectral peaks at 4.6 yr （2.7 yr）. EOF-P2 not only had a closer association with E1 Nifio-Southern Oscillation （ENSO）, but also showed a faster response to ENSO than EOF-P1 based on their lead-lag relationships with ENSO. During the development of ENSO, the South Pacific SSTA associated with ENSO for both PI and P2 showed a significant eastward propagation. However, after the peak of ENSO, EOF-P1 showed a stronger persistence than EOF-P2, which still showed eastward propagation. The variability of the SSTA associated with the whole process of ENSO evolution during P1 and the SSTA associated with the development of ENSO during P2 support the existence of ocean-to-atmosphere forcing, but the SSTA associated with the decay of ENSO shows the phenomenon of atmosphere-to-ocean forcing.
文摘In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc networks is proposed.In this scheme, a sender can simultaneously signcrypt n messeges for n receivers, and a receiver can unsigncrypt the ciphertext to get his message with his own private key.An analysis of this scheme indicates that it achieves authenticity and confidentiality in the random oracle model while being of lower computation and communication overhead.Finally, for the application of our scheme in ad hoc, a threshold key updating protocol for ad hoc networks is given.
基金Item Sponsored by Special Fund Achievements Transformation Projects in Jiangsu of China(BA2012030)
文摘One-dimensional detonation model and two-dimensional P-M （Prandtl-Meyer） expanding model of double vertical explosive welding were established. A one-dimensional formula of flyer plate velocity was obtained and the bending angle curve representing flying attitude of flyer plate in double vertical was deduced as well. Compared with single parallel explosive welding, the double vertical explosive welding combines two cladding plates in one explosion. Due to closed charging structure, the influence of rarefaction wave on the plate＇s surface in double vertical explosive welding is eliminated and explosion loading time and displacement are increased, resulting in the increase of flyer velocity and energy utilization rate by 1.3 times to 1.6 times in different mass ratios. The analysis of microstructure in bonding zone of double vertical cladding plate under traditional charging shows that there is a clear over-melting near the interface, which is in line with the conclusion of detonation mechanism.
基金The National Natural Science Foundation under contract Nos 41206163,41076048 and 41376012the Operation Expenses for Universities'Basic Scientific Research of Central Authorities under contract Nos 2011B05714 and 2014B06514
文摘The rip currents induced by waves off arc-shaped coastlines are seriously harmful to humans, but understanding of their characteristics is lacking. In this study, the FUNWAVE model was used to calculate the wave-induced currents in the Haller experiment and the ideal arc-shaped coast similar to Sanya Dadonghai, Hainan Province,China. The results showed that the FUNWAVE model has considerable ability to simulate the rip currents, and it was used to further simulate rip currents off arc-shaped coastlines to investigate their characteristics. The rip currents were found to be stronger as the curvature of arc-shaped coastline increased. Coastal beach slope exerts a significant influence on rip currents; in particular, an overly steep or overly mild slope is not conducive to creating rip currents. Furthermore, the rip currents were found to become weaker as the size of arc-shaped coast decreased. When the height and period of waves increase, the strength of rip currents also increases, and, in some cases, wave heights of 0.4 m may produce dangerous rip currents.
基金supported by National Natural Science Foundation of China (Grant No. 40975031)
文摘In nonlinear error growth dynamics,the initial error cannot be accurately determined,and the forecast error,which is also uncertain,can be considered to be a random variable.Entropy in information theory is a natural measure of the uncertainty of a random variable associated with a probability distribution.This paper effectively combines statistical information theory and nonlinear error growth dynamics,and introduces some fundamental concepts of entropy in information theory for nonlinear error growth dynamics.Entropy based on nonlinear error can be divided into time entropy and space entropy,which are used to estimate the predictabilities of the whole dynamical system and each of its variables.This is not only applicable for investigating the dependence between any two variables of a multivariable system,but also for measuring the influence of each variable on the predictability of the whole system.Taking the Lorenz system as an example,the entropy of nonlinear error is applied to estimate predictability.The time and space entropies are used to investigate the spatial distribution of predictability of the whole Lorenz system.The results show that when moving around two chaotic attractors or near the edge of system space,a Lorenz system with lower sensitivity to the initial field behaves with higher predictability and a longer predictability limit.The example analysis of predictability of the Lorenz system demonstrates that the predictability estimated by the entropy of nonlinear error is feasible and effective,especially for estimation of predictability of the whole system.This provides a theoretical foundation for further work in estimating real atmospheric multivariable joint predictability.
基金This work was supported by the National Key Research and Development Program of China(2017YFE0133800)the Distinguished Youth Foundation of Anhui Province(1708085J09).
文摘Formamidinium lead halide(α-FAPbI3)with a broad light absorption spectrum,has recently received considerable attention in optoelectronic applications.However,the FAI-PbI2-DMSO(DMSO:dimethyl sulfoxide)intermediate anisotropic fibers readily form a non-perovskite phase(δ-FAPbI3)and uncontrolled excess PbI2,which hinders the further increase in the efficiencies of solar cells.Caculations indicate that iodine defects in polycrystalline films would enlarge the perovskite tolerance factor and result in the formation of iodide Frenkel defects.Herein,we introduce a post-treatment technique to heal the as-prepared FAPbI3 thin layer and restrain the notoriousδ-FAPbI3 through vacancy filling.Furthermore,a new intermediate phase of FAI-PbI2-DMSO-FACl led to a high-quality perovskite layer with an enlarged average grain size that exceeded 2μm.Consequently,the power conversion efficiencies of FAPbI3 solar cells were significantly enhanced due to the high crystallity of the pureα-phase perovskite.Therefore,this method can be used to obtain high pure-black perovskite films and efficient solar cells.
