Blocker tag attack is one of the denial-of-service(DoS)attacks that threatens the privacy and security of RFID systems.The attacker interferes with the blocked tag by simulating a fake tag with the same ID,thus causin...Blocker tag attack is one of the denial-of-service(DoS)attacks that threatens the privacy and security of RFID systems.The attacker interferes with the blocked tag by simulating a fake tag with the same ID,thus causing a collision of message replies.In many practical scenarios,the number of blocked tags may vary,or even be small.For example,the attacker may only block the important customers or high-value items.To avoid the disclosure of privacy and economic losses,it is of great importance to fast pinpoint these blocked ones.However,existing works do not take into account the impact of the number of blocked tags on the execution time and suffer from incomplete identification of blocked tags,long identification time or privacy leakage.To overcome these limits,we propose a cross layer blocked tag identification protocol(CLBI).CLBI consists of multiple rounds,in which it enables multiple unblocked tags to select one time slot and concurrently verify them by using tag estimation in physical layer.Benefiting from the utilization of most collision slots,the execution time can be greatly reduced.Furthermore,for efficient identification of blocked tags under different proportions,we propose a hybrid protocol named adaptive cross layer blocked tag identification protocol(A-CLBI),which estimates the remaining blocked tag in each round and adjusts the identification strategy accordingly.Extensive simulations show that our protocol outperforms state-of-the-art blocked tags identification protocol.展开更多
Controlled release of TDI and hence the cure characteristics of several blocked TDI with HTPB are reported. The reactions were followed through viscosity measurements as a function of time and temperature under the ca...Controlled release of TDI and hence the cure characteristics of several blocked TDI with HTPB are reported. The reactions were followed through viscosity measurements as a function of time and temperature under the catalytic influence of triethylamine. The effect of nature of substituents present on the end capping substrate, temperature, solvent, basicity of catalyst and kinetics thereon have been studied.展开更多
Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol...Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol, thiophenol, p-chloropheno1, p-nitrophenol,p-cresol, resorcinol, naphthols, caprolactam and butylated-hydroxytoluene were used as blockingagents. Viscosity measurements have been carried out using a mixture of HTPB and blocked TDIin cyclohexanone in the presence of the catalysts at 50℃ and 60℃ using Haake rotational vis-cometer. Viscosity measurements have also been carried out with 50% solids such as ammonium sulphate along with HTPB and TDI adduct.展开更多
The dose-effect relationship of the fre-quencies of micronuclei was studied in cy-tokinesis-blocked human lymphocytes afterin vitro irradiation of 180 kVp X-rays.Thebest fit in the dose range of 1-5 Gy waslinear-quadr...The dose-effect relationship of the fre-quencies of micronuclei was studied in cy-tokinesis-blocked human lymphocytes afterin vitro irradiation of 180 kVp X-rays.Thebest fit in the dose range of 1-5 Gy waslinear-quadratic.The micronuclei rate ofthe present results was compared with展开更多
One-cell mouse embryos from KM strain and B6C3F1 strain were cultured in M16 medium, in which 2-cell block generally occurs. Embryos of KM strain exhibited 2-cell block, whereas B6C3F1 embryos, which are regarded as a...One-cell mouse embryos from KM strain and B6C3F1 strain were cultured in M16 medium, in which 2-cell block generally occurs. Embryos of KM strain exhibited 2-cell block, whereas B6C3F1 embryos, which are regarded as a nonblocking strain, proceeded to the 4-cell stage in our culture condition. It is often assumed that the block of early development is due to the failure of/ygotic gene activation (ZGA) in cultured embryos. In this study we examined protein synthesis patterns by two-dimensional gel eleetrophoresis of [35 S] methionine radiolabeled 2-cell embryos. Embryos from the blocking strain and the nonblocking strain were compared in their development both in vitro and in vivo. The detection of TRC expression, a marker of ZGA. at 42 h post hCG in KM embryos developed in vitro suggested that ZGA was also initiated even in the 2-cell arrested embryos. Nevertheless, a significant delay of ZGA was observed in KM strain as compared with normally developed B6C3F1 embryos. At the very beginning of major ZGA as early as 36 h post hCG, TRC has already been expressed in B6C3F1 embryos developed in vitro and KM embryos developed in vivo. But for 2-cell blocked KM embryos, TRC was still not detectable even at 38 h post hCG. These evidences suggest that 2-cell-blocked embryos do initiate ZGA, and that 2-cell block phenomenon is due not to the disability in initiating ZGA. but to a delay of ZGA.展开更多
In finite element analysis(FEA),optimizing the storage requirements of the global stiffness matrix and enhancing the computational efficiency of solving finite element equations are pivotal objectives.To address these...In finite element analysis(FEA),optimizing the storage requirements of the global stiffness matrix and enhancing the computational efficiency of solving finite element equations are pivotal objectives.To address these goals,we present a novel method for compressing the storage of the global stiffness matrix,aimed at minimizing memory consumption and enhancing FEA efficiency.This method leverages the block symmetry of the global stiffness matrix,hence named the blocked symmetric compressed sparse column(BSCSC)method.We also detail the implementation scheme of the BSCSC method and the corresponding finite element equation solution method.This approach optimizes only the global stiffness matrix index,thereby reducing memory requirements without compromising FEA computational accuracy.We then demonstrate the efficiency and memory savings of the BSCSC method in FEA using 2D and 3D cantilever beams as examples.In addition,we employ the BSCSC method to an engine connecting rod model to showcase its superiority in solving complex engineering models.Furthermore,we extend the BSCSC method to isogeometric analysis and validate its scalability through two examples,achieving up to 66.13%memory reduction and up to 72.06%decrease in total computation time compared to the traditional compressed sparse column method.展开更多
Astronomical detection at infrared wavelengths is crucial in astrophysics due to the critical information in this wavelength range.Blocked impurity band(BIB) infrared detectors are desirable for space-based astronomic...Astronomical detection at infrared wavelengths is crucial in astrophysics due to the critical information in this wavelength range.Blocked impurity band(BIB) infrared detectors are desirable for space-based astronomical observation due to their broad response range, low dark currents, high quantum efficiencies, and excellent radiation resistance. In this review, typical BIB device structures and device physics development are first introduced. Subsequently, we discuss progress in Si-based BIB detectors with different doping types and emphasize their applications in space-based infrared detection. Additionally, we discuss recent efforts on pixel performance optimization, response extension, and higher operating temperature devices. Finally,we conclude by proposing the challenges and perspectives of BIB detectors with improved detection performances.展开更多
Objective To investigate the effect of histamine type Ⅱ (H 2) receptors of the CD + 8 cells from aplastic anemia (AA) patients on the inhibition of hematopoiesis. Methods Employing the modification of the panni...Objective To investigate the effect of histamine type Ⅱ (H 2) receptors of the CD + 8 cells from aplastic anemia (AA) patients on the inhibition of hematopoiesis. Methods Employing the modification of the panning method with monoclonal antibody the CD + 8 cells from peri pheral blood mononulcear cells of 17 aplastic anemia patients were obtained. The ribs moved during thoracic operations from 17 patients with non hematologic diseases were as normal bone marrow resource. According to different group 2×10 4/ml CD + 8 cells from AA patients and/or 1.0×10 5 mol/L or 0.5×10 5 mol/L cimetidine alone or in combination were added in the normal CFU GM cultures. Reusults The normal CFU GM from the rib bone marrows was 147.69±24.75/10 5 cells (±s), if 2×10 4/ml CD + 8 cells from AA patients were added in the cultures, the CFU GM formation significantly decreased (89.49±20.49/10 5 cells, P<0.01). If CD + 8 cells from AA patients and 1.0×10 5 mol/L or 0.5×10 5 mol/L cimetidine were in combination added in the cultures, the CFU GM were 144.96±25.34/10 5 cells or 156.28± 32.81/10 5 cells respectively, compared with normal group P>0.05. If 1.0×10 5 mol/L or 0.5×10 5 mol/L cimetidine was added alone in the cultures, the CFU GM number were 110.47±27.46/10 5 cells (compared with control P<0.01) or 160.06±32.22/10 5 cells (compared with control P>0.05) respectively. Conclusion 1.0×10 5 mol/L and 0.5×10 5 mol/L H 2 receptor antagonist cimetidine completely abolished the suppressive effect of CD + 8 cells from AA patients on the growth of normal CFU GM and lower concentration cimetidine (0.5×10 5 mol/L) didn't suppress the growth of normal CFU GM.展开更多
One type of covariance structure is known as blocked compound symmetry.Recently,Roy et al.(J Multivar Anal 144:81–90,2016)showed that,assuming this covariance structure,unbiased estimators are optimal under normality...One type of covariance structure is known as blocked compound symmetry.Recently,Roy et al.(J Multivar Anal 144:81–90,2016)showed that,assuming this covariance structure,unbiased estimators are optimal under normality and described hypothesis testing for independence as an open problem.In this paper,we derive the distributions of unbiased estimators and consider hypothesis testing for independence.Representative test statistics such as the likelihood ratio criterion,Waldstatistic,Rao’s score statistic,and gradient statistic are derived,and we evaluate the accuracy of the test using these statistics through numerical simulations.The power of the Wald test is the largest when the dimension is high,and the power of the likelihood ratio test is the largest when the dimension is low.展开更多
The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-m...The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-middle Miocene deformed rocks of the inter-Andean valley between the Western and Central Cordilleras of Colombia.However,uncertainty remains about the age of the latest accretionary phases of the Panama-ChocóBlock.Poorly studied late Miocene volcanic rocks within the northern inter-Andean valley may provide key information to constrain the temporality of that final collision.Here,we study the deformational features of the~12-6 Ma extrusive rocks of the Combia Volcanic Province located in the northwestern Andes(Colombia).We present anisotropy of magnetic susceptibility(AMS)data for pyroclastic and volcanic rocks within the AmagáBasin,an inter-Andean depression with Oligocene-middle Miocene sedimentary rocks that recorded NW-SE compression and NE-SW simple shear caused by the Panama-ChocóBlock collision.We identified that the magnetic fabrics of the extrusive rocks of the Combia Volcanic Province reveal flow directions that indicate the occurrence of ancient volcanoes in the central axis of the AmagáBasin.Some of these fabrics do not contain any deformational features,whereas others record the same structural regime as the Oligocene-middle Miocene sedimentary rocks.We infer that variations in the intensity of the deformation promoted late Miocene local fault reactivations that,in contrast to the Oligocene-middle Miocene deformational events,did not affect the entire AmagáBasin.Age differences among the studied sections can also explain the different deformational patterns identified in the basin.Both interpretations suggest that the most significant collisional events of the Panama-ChocóBlock occurred in the Oligocene-middle Miocene,whereas the formation of the Combia Volcanic Province may have either followed or coincided with the latest stages of the accretion.展开更多
目的针对复杂的内河河道环境,漂浮垃圾中小目标物体占大多数且易受来自水面和岸边环境反光等因素影响,造成目标外形模糊,易被遮挡,给目标检测带来困难;提出了一种基于改进YOLOv7的河道漂浮垃圾检测算法。方法首先,针对河道漂浮垃圾的受...目的针对复杂的内河河道环境,漂浮垃圾中小目标物体占大多数且易受来自水面和岸边环境反光等因素影响,造成目标外形模糊,易被遮挡,给目标检测带来困难;提出了一种基于改进YOLOv7的河道漂浮垃圾检测算法。方法首先,针对河道漂浮垃圾的受环境影响外形发生变化,通过改进SPPCSPC模块,增强对小目标物体的特征提取能力;其次,加入中心化特征金字塔,通过ROI(region of interest)与特征金字塔进行加权融合,方便对于不同尺度目标的检测。最后,由于针对传统IoU(intersection over union)对于小目标物体位置偏差非常敏感,降低了检测性能。采用了Wasserstein Distance来替代IoU作为检测衡量指标,通过引入基于NWD(Normalized Wasserstein Distance)的损失函数,从而提高检测精度。结果实验结果表明:改进YOLOv7算法模型准确率增加3.1%达到89.7%,并在IoU为0.5以及IoU在0.5~0.95情况下,平均均值精度分别增加了6%、4.6%,分别达到87.8%、43.4%,检测结果优于其他经典检测模型。结论通过实验结果可以看出,改进后模型在检测精度上有显著提升,对于实际应用具有一定的参考价值。展开更多
Lymphatic-venous anastomosis(LVA)surgery has recently emerged as a potential treatment for Alzheimer’s disease(AD)in China.This minimally invasive microsurgical procedure has been used for decades to treat lymphoedem...Lymphatic-venous anastomosis(LVA)surgery has recently emerged as a potential treatment for Alzheimer’s disease(AD)in China.This minimally invasive microsurgical procedure has been used for decades to treat lymphoedema,typically in the limbs,to decompress blocked lymphatic drainage pathways.展开更多
Multiple instances of the Late Cretaceous granodiorites within the Anglonggangri region of the northwestern Lhasa Block were identified,their petrogenesis were explored and mineralization potential were assessed.The z...Multiple instances of the Late Cretaceous granodiorites within the Anglonggangri region of the northwestern Lhasa Block were identified,their petrogenesis were explored and mineralization potential were assessed.The zircon U-Pb dating of the Anglonggangri granodiorites revealed ages of 82.8 and 80.8 Ma.Granodiorite samples have SiO2 contents of 64.36-68.33 wt%,with high Sr/Y(55-95)and A/CNK ratios(0.99-1.06).Zirconε_(Hf)(t)values range from−0.3 to+16.2.Two granodiorite samples have(^(87)Sr/^(86)Sr)i values of 0.7034 and 0.7043 and positiveɛNd(t)values of 3.51 and 3.83.These geochemical properties indicate that they are adakitic rocks formed by partial melting of the juvenile thickened lower crust,slightly contaminated with material from the mantle due to the small-scale delamination of the lower crust.The zircons in the granodiorites have moderate Ce/Nd(2.5-43),logfO2(−20.0 to−9.6),andΔFMQ(−1.28 to+4.00)values;low(Ce/Nd)/Y(0.001-0.049)ratios;and high Dy/Yb(0.17-1.16)ratios,which indicate that these granodiorites exhibit moderate oxygen fugacity and lower magma water content than the Miocene Gangdese porphyry copper deposits associated with high-Sr/Y granites.Their ability to create porphyry-type copper deposits could have been hampered by their low magma water content and moderate oxygen fugacity.展开更多
基金This work was supported in part by the National Natural Science Foundation of China under project contracts Nos.61701082,61701116,61601093,61971113 and 61901095in part by National Key R&D Program under project Nos.2018YFB1802102 and 2018AAA0103203+3 种基金in part by Guangdong Provincial Research and Development Plan in Key Areas under project contract Nos.2019B010141001 and 2019B010142001in part by Sichuan Provincial Science and Technology Planning Program under project contracts Nos.2018HH0034,2019YFG0418,2019YFG0120 and 2018JY0246in part by the fundamental research funds for the Central Universities under project contract No.ZYGX2016J004in part by Science and Technology on Electronic Information Control Laboratory.
文摘Blocker tag attack is one of the denial-of-service(DoS)attacks that threatens the privacy and security of RFID systems.The attacker interferes with the blocked tag by simulating a fake tag with the same ID,thus causing a collision of message replies.In many practical scenarios,the number of blocked tags may vary,or even be small.For example,the attacker may only block the important customers or high-value items.To avoid the disclosure of privacy and economic losses,it is of great importance to fast pinpoint these blocked ones.However,existing works do not take into account the impact of the number of blocked tags on the execution time and suffer from incomplete identification of blocked tags,long identification time or privacy leakage.To overcome these limits,we propose a cross layer blocked tag identification protocol(CLBI).CLBI consists of multiple rounds,in which it enables multiple unblocked tags to select one time slot and concurrently verify them by using tag estimation in physical layer.Benefiting from the utilization of most collision slots,the execution time can be greatly reduced.Furthermore,for efficient identification of blocked tags under different proportions,we propose a hybrid protocol named adaptive cross layer blocked tag identification protocol(A-CLBI),which estimates the remaining blocked tag in each round and adjusts the identification strategy accordingly.Extensive simulations show that our protocol outperforms state-of-the-art blocked tags identification protocol.
文摘Controlled release of TDI and hence the cure characteristics of several blocked TDI with HTPB are reported. The reactions were followed through viscosity measurements as a function of time and temperature under the catalytic influence of triethylamine. The effect of nature of substituents present on the end capping substrate, temperature, solvent, basicity of catalyst and kinetics thereon have been studied.
文摘Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol, thiophenol, p-chloropheno1, p-nitrophenol,p-cresol, resorcinol, naphthols, caprolactam and butylated-hydroxytoluene were used as blockingagents. Viscosity measurements have been carried out using a mixture of HTPB and blocked TDIin cyclohexanone in the presence of the catalysts at 50℃ and 60℃ using Haake rotational vis-cometer. Viscosity measurements have also been carried out with 50% solids such as ammonium sulphate along with HTPB and TDI adduct.
文摘The dose-effect relationship of the fre-quencies of micronuclei was studied in cy-tokinesis-blocked human lymphocytes afterin vitro irradiation of 180 kVp X-rays.Thebest fit in the dose range of 1-5 Gy waslinear-quadratic.The micronuclei rate ofthe present results was compared with
基金supported by grants from Shanghai Scientific Development Foundation(No.01JC14047)National Key Basic Research Project“973”(No.G199905592).
文摘One-cell mouse embryos from KM strain and B6C3F1 strain were cultured in M16 medium, in which 2-cell block generally occurs. Embryos of KM strain exhibited 2-cell block, whereas B6C3F1 embryos, which are regarded as a nonblocking strain, proceeded to the 4-cell stage in our culture condition. It is often assumed that the block of early development is due to the failure of/ygotic gene activation (ZGA) in cultured embryos. In this study we examined protein synthesis patterns by two-dimensional gel eleetrophoresis of [35 S] methionine radiolabeled 2-cell embryos. Embryos from the blocking strain and the nonblocking strain were compared in their development both in vitro and in vivo. The detection of TRC expression, a marker of ZGA. at 42 h post hCG in KM embryos developed in vitro suggested that ZGA was also initiated even in the 2-cell arrested embryos. Nevertheless, a significant delay of ZGA was observed in KM strain as compared with normally developed B6C3F1 embryos. At the very beginning of major ZGA as early as 36 h post hCG, TRC has already been expressed in B6C3F1 embryos developed in vitro and KM embryos developed in vivo. But for 2-cell blocked KM embryos, TRC was still not detectable even at 38 h post hCG. These evidences suggest that 2-cell-blocked embryos do initiate ZGA, and that 2-cell block phenomenon is due not to the disability in initiating ZGA. but to a delay of ZGA.
基金supported by the National Natural Science Foundation of China(Grant No.52075184)Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2024A1515011786).
文摘In finite element analysis(FEA),optimizing the storage requirements of the global stiffness matrix and enhancing the computational efficiency of solving finite element equations are pivotal objectives.To address these goals,we present a novel method for compressing the storage of the global stiffness matrix,aimed at minimizing memory consumption and enhancing FEA efficiency.This method leverages the block symmetry of the global stiffness matrix,hence named the blocked symmetric compressed sparse column(BSCSC)method.We also detail the implementation scheme of the BSCSC method and the corresponding finite element equation solution method.This approach optimizes only the global stiffness matrix index,thereby reducing memory requirements without compromising FEA computational accuracy.We then demonstrate the efficiency and memory savings of the BSCSC method in FEA using 2D and 3D cantilever beams as examples.In addition,we employ the BSCSC method to an engine connecting rod model to showcase its superiority in solving complex engineering models.Furthermore,we extend the BSCSC method to isogeometric analysis and validate its scalability through two examples,achieving up to 66.13%memory reduction and up to 72.06%decrease in total computation time compared to the traditional compressed sparse column method.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFB2009301)the National Natural Science Foundation of China(Grant Nos.11933006,61805060,62175045,62104053,62174063,and U2141240)+2 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LGF21F050001)Hangzhou Key Research and Development Program(Grant No.20212013B01)Hangzhou Science and Technology Bureau(Grant No.TD2020002)。
文摘Astronomical detection at infrared wavelengths is crucial in astrophysics due to the critical information in this wavelength range.Blocked impurity band(BIB) infrared detectors are desirable for space-based astronomical observation due to their broad response range, low dark currents, high quantum efficiencies, and excellent radiation resistance. In this review, typical BIB device structures and device physics development are first introduced. Subsequently, we discuss progress in Si-based BIB detectors with different doping types and emphasize their applications in space-based infrared detection. Additionally, we discuss recent efforts on pixel performance optimization, response extension, and higher operating temperature devices. Finally,we conclude by proposing the challenges and perspectives of BIB detectors with improved detection performances.
文摘Objective To investigate the effect of histamine type Ⅱ (H 2) receptors of the CD + 8 cells from aplastic anemia (AA) patients on the inhibition of hematopoiesis. Methods Employing the modification of the panning method with monoclonal antibody the CD + 8 cells from peri pheral blood mononulcear cells of 17 aplastic anemia patients were obtained. The ribs moved during thoracic operations from 17 patients with non hematologic diseases were as normal bone marrow resource. According to different group 2×10 4/ml CD + 8 cells from AA patients and/or 1.0×10 5 mol/L or 0.5×10 5 mol/L cimetidine alone or in combination were added in the normal CFU GM cultures. Reusults The normal CFU GM from the rib bone marrows was 147.69±24.75/10 5 cells (±s), if 2×10 4/ml CD + 8 cells from AA patients were added in the cultures, the CFU GM formation significantly decreased (89.49±20.49/10 5 cells, P<0.01). If CD + 8 cells from AA patients and 1.0×10 5 mol/L or 0.5×10 5 mol/L cimetidine were in combination added in the cultures, the CFU GM were 144.96±25.34/10 5 cells or 156.28± 32.81/10 5 cells respectively, compared with normal group P>0.05. If 1.0×10 5 mol/L or 0.5×10 5 mol/L cimetidine was added alone in the cultures, the CFU GM number were 110.47±27.46/10 5 cells (compared with control P<0.01) or 160.06±32.22/10 5 cells (compared with control P>0.05) respectively. Conclusion 1.0×10 5 mol/L and 0.5×10 5 mol/L H 2 receptor antagonist cimetidine completely abolished the suppressive effect of CD + 8 cells from AA patients on the growth of normal CFU GM and lower concentration cimetidine (0.5×10 5 mol/L) didn't suppress the growth of normal CFU GM.
文摘One type of covariance structure is known as blocked compound symmetry.Recently,Roy et al.(J Multivar Anal 144:81–90,2016)showed that,assuming this covariance structure,unbiased estimators are optimal under normality and described hypothesis testing for independence as an open problem.In this paper,we derive the distributions of unbiased estimators and consider hypothesis testing for independence.Representative test statistics such as the likelihood ratio criterion,Waldstatistic,Rao’s score statistic,and gradient statistic are derived,and we evaluate the accuracy of the test using these statistics through numerical simulations.The power of the Wald test is the largest when the dimension is high,and the power of the likelihood ratio test is the largest when the dimension is low.
基金supported financially by the National Natural Science Foundation of China(Grants W2433104 to V.A.P.and 42225402 to J.L.)the China Postdoctoral Science Foundation(Grant 2024M753205 to V.A.P.)+2 种基金the Institute of Geology and Geophysics of the Chinese Academy of Sciences(International Fellowship for Postdoctoral Researchers,Grant 2025PD02 to V.A.P.)an association between ECOS-NORD(France)and Colciencias/Icetex(Colombia)(Grant C12U01 to M.I.M.)Part of this project was developed under a junior fellowship scheme of Colciencias(Colombia)(Grant 706-2015 to V.A.P.),which also supported the undergraduate final project of A.T.
文摘The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-middle Miocene deformed rocks of the inter-Andean valley between the Western and Central Cordilleras of Colombia.However,uncertainty remains about the age of the latest accretionary phases of the Panama-ChocóBlock.Poorly studied late Miocene volcanic rocks within the northern inter-Andean valley may provide key information to constrain the temporality of that final collision.Here,we study the deformational features of the~12-6 Ma extrusive rocks of the Combia Volcanic Province located in the northwestern Andes(Colombia).We present anisotropy of magnetic susceptibility(AMS)data for pyroclastic and volcanic rocks within the AmagáBasin,an inter-Andean depression with Oligocene-middle Miocene sedimentary rocks that recorded NW-SE compression and NE-SW simple shear caused by the Panama-ChocóBlock collision.We identified that the magnetic fabrics of the extrusive rocks of the Combia Volcanic Province reveal flow directions that indicate the occurrence of ancient volcanoes in the central axis of the AmagáBasin.Some of these fabrics do not contain any deformational features,whereas others record the same structural regime as the Oligocene-middle Miocene sedimentary rocks.We infer that variations in the intensity of the deformation promoted late Miocene local fault reactivations that,in contrast to the Oligocene-middle Miocene deformational events,did not affect the entire AmagáBasin.Age differences among the studied sections can also explain the different deformational patterns identified in the basin.Both interpretations suggest that the most significant collisional events of the Panama-ChocóBlock occurred in the Oligocene-middle Miocene,whereas the formation of the Combia Volcanic Province may have either followed or coincided with the latest stages of the accretion.
文摘目的针对复杂的内河河道环境,漂浮垃圾中小目标物体占大多数且易受来自水面和岸边环境反光等因素影响,造成目标外形模糊,易被遮挡,给目标检测带来困难;提出了一种基于改进YOLOv7的河道漂浮垃圾检测算法。方法首先,针对河道漂浮垃圾的受环境影响外形发生变化,通过改进SPPCSPC模块,增强对小目标物体的特征提取能力;其次,加入中心化特征金字塔,通过ROI(region of interest)与特征金字塔进行加权融合,方便对于不同尺度目标的检测。最后,由于针对传统IoU(intersection over union)对于小目标物体位置偏差非常敏感,降低了检测性能。采用了Wasserstein Distance来替代IoU作为检测衡量指标,通过引入基于NWD(Normalized Wasserstein Distance)的损失函数,从而提高检测精度。结果实验结果表明:改进YOLOv7算法模型准确率增加3.1%达到89.7%,并在IoU为0.5以及IoU在0.5~0.95情况下,平均均值精度分别增加了6%、4.6%,分别达到87.8%、43.4%,检测结果优于其他经典检测模型。结论通过实验结果可以看出,改进后模型在检测精度上有显著提升,对于实际应用具有一定的参考价值。
基金the Ministry of Science and Technology of the People's Republic of China(2021ZD0201804,GW)the National Natural Science Foundation of China(82371416,HW).
文摘Lymphatic-venous anastomosis(LVA)surgery has recently emerged as a potential treatment for Alzheimer’s disease(AD)in China.This minimally invasive microsurgical procedure has been used for decades to treat lymphoedema,typically in the limbs,to decompress blocked lymphatic drainage pathways.
基金jointly supported by the National Key Research&Development Program of China(2021YFC2900100)the Basic Research Fund of the Chinese Academy of Geological Sciences(KK2306)+1 种基金the Geological Survey Project(DD20230360,DD20243483)the Sichuan Provincial Natural Science Foundation(2023NSFSC0798).
文摘Multiple instances of the Late Cretaceous granodiorites within the Anglonggangri region of the northwestern Lhasa Block were identified,their petrogenesis were explored and mineralization potential were assessed.The zircon U-Pb dating of the Anglonggangri granodiorites revealed ages of 82.8 and 80.8 Ma.Granodiorite samples have SiO2 contents of 64.36-68.33 wt%,with high Sr/Y(55-95)and A/CNK ratios(0.99-1.06).Zirconε_(Hf)(t)values range from−0.3 to+16.2.Two granodiorite samples have(^(87)Sr/^(86)Sr)i values of 0.7034 and 0.7043 and positiveɛNd(t)values of 3.51 and 3.83.These geochemical properties indicate that they are adakitic rocks formed by partial melting of the juvenile thickened lower crust,slightly contaminated with material from the mantle due to the small-scale delamination of the lower crust.The zircons in the granodiorites have moderate Ce/Nd(2.5-43),logfO2(−20.0 to−9.6),andΔFMQ(−1.28 to+4.00)values;low(Ce/Nd)/Y(0.001-0.049)ratios;and high Dy/Yb(0.17-1.16)ratios,which indicate that these granodiorites exhibit moderate oxygen fugacity and lower magma water content than the Miocene Gangdese porphyry copper deposits associated with high-Sr/Y granites.Their ability to create porphyry-type copper deposits could have been hampered by their low magma water content and moderate oxygen fugacity.
