The measurement of low-level radioactivity using high-purity germanium(HPGe)detectors is important in applications such as environmental background radiation,material screening,and rare decays.The dead layers,dead zon...The measurement of low-level radioactivity using high-purity germanium(HPGe)detectors is important in applications such as environmental background radiation,material screening,and rare decays.The dead layers,dead zones,aluminum shell thickness,and diameter of Ge crystals are the most influential factors affecting the performance of HPGe detectors;hence,precise modeling of the physical conditions of the detectors is highly desirable.In this study,the GEANT4 simulation framework with an optimized detector geometry adequately replicated the experimentally recorded spectrum.These detector simulations explored the idea of realizing a dead zone(an inactive volume)at the backend of an n-type coaxial Gecrystal.Using multigamma sources,the effect of true coincidence summing(TCS)on the full energy peak(FEP)efficiency calibration of an HPGe detector was investigated as a function of sample-to-detector distance.Good agreements between the simulated and experimental efficiencies as well as the simulated and analytically calculated summing coincidence correction coefficients were achieved.At a short distance between the source and detector,calculating the correction factors for a strong source posed challenges owing to significant deadtime and pile-up effects of the detection system.The described methodology can efficiently determine summing peak probabilities at short sample-to-detector distances.展开更多
BACKGROUND The prevalence of addiction makes it a significant public health issue.Recently,transcranial magnetic stimulation(TMS)has garnered significant attention as a promising treatment for addiction.AIM To analyze...BACKGROUND The prevalence of addiction makes it a significant public health issue.Recently,transcranial magnetic stimulation(TMS)has garnered significant attention as a promising treatment for addiction.AIM To analyze development trends and research hotspots in TMS-based addiction treatment using a bibliometric approach.METHODS Articles on TMS-based addiction treatment from 2001 to 2023 were sourced from the Science Citation Index Expanded in the Web of Science Core Collection.CiteSpace software,VOSviewer,the"bibliometrix"R software package,and the bibliometric online analysis platform were used to analyze the current publication trends and hotspots.RESULTS Total 190 articles on TMS-based addiction treatment were identified,with clinical studies being the most prevalent.The United States led in both publication volume and international collaborations.Medical University of South Carolina and Zangen A were the most productive institution and author,respectively.Neurobiology,alcohol use disorder,and repetitive TMS were the most recent research hotspots.CONCLUSION Future research should focus on the neurobiological mechanisms underlying TMS-based addiction treatment.This study offers comprehensive insights and recommendations for advancing research on TMS-based addiction treatment.展开更多
BACKGROUND Depression has become a global public health problem.In recent years,transcranial magnetic stimulation(TMS)has gained considerable attention as a noninvasive treatment for depression.AIM To investigate the ...BACKGROUND Depression has become a global public health problem.In recent years,transcranial magnetic stimulation(TMS)has gained considerable attention as a noninvasive treatment for depression.AIM To investigate the research hotspots and trends in the field of TMS-based depression treatment from a bibliometric perspective.METHODS Using the Web of Science Core Collection,articles published between 2003 and 2022 on TMS-based depression treatment were retrieved from the science citation index expanded.The publication trends and research hotspots were analyzed using VOSviewer,CiteSpace,and the bibliometric online analysis platform.Regression analysis was performed using Microsoft Excel 2021 to predict publication growth trends.RESULTS We identified a total of 702 articles on TMS-based depression treatment with a predominance of clinical studies.Analysis of collaborative networks showed that the United States,the University of Toronto,and Daskalakis ZJ were identified as the most impactful country,institution,and researcher,respectively.In keyword burst analysis,it was found that theta burst stimulation(TBS),functional connectivity,and frequency were the most recent research hotspots.CONCLUSION TMS provides a novel therapeutic option for patients with treatment-resistant depression.Neuroimaging technology enables more precise TMS treatment,while the novel TMS modality,TBS,enhances both therapeutic efficacy and patient experience in TMS-based depression treatment.The integration of neuroimaging techniques with TBS represents a promising research direction for advancing TMS-based depression treatment.This study presents systematic information and recommendations to guide future research on TMS-based depression treatment.展开更多
With the increasing accuracy requirements of satellite magnetic detection missions,reducing low-frequency noise has become a key focus of satellite magnetic cleanliness technology.Traditional satellite magnetic simula...With the increasing accuracy requirements of satellite magnetic detection missions,reducing low-frequency noise has become a key focus of satellite magnetic cleanliness technology.Traditional satellite magnetic simulation methods have matured in static magnetic dipole simulations,but there is still significant room for optimization in the simulation and computation of low-frequency magnetic dipole models.This study employs the Gauss-Newton method and Fourier transform techniques for modeling and simulating low-frequency magnetic dipoles.Compared to the traditional particle swarm optimization(PSO)algorithm,this method achieves significant improvements,with errors reaching the order of10^(-13)%under noise-free conditions and maintaining an error level of less than 0.5%under 10%noise.Additionally,the use of Fourier transform and the Gauss-Newton method enables high-precision magnetic field frequency identification and rapid computation of the dipole position and magnetic moment,greatly enhancing the computational efficiency and accuracy of the model.展开更多
Interfacial crystallization of polyoxymethylene/poly(butylene succinate)blends induced by the polyamide 6(PA6)fiber was investigated.Due to strong heterogeneous nucleating ability,dense nuclei were generated on the su...Interfacial crystallization of polyoxymethylene/poly(butylene succinate)blends induced by the polyamide 6(PA6)fiber was investigated.Due to strong heterogeneous nucleating ability,dense nuclei were generated on the surface of the PA6 fiber,which compelled the growth of twisted lamellae perpendicular to the PA6 fiber.As a result,unique interfacial banded transcrystallization was formed,which is rarely found before.Crystallization temperature was dominant in determining the nucleation activity of the PA6 fiber,further affecting the architecture of banded transcrystallization.With the increase of crystallization temperature,the nucleation density decreased to give more growth space for the twisted lamellae around the fiber.The wave-like banded stripes were transformed into fan-like stripes.Accordingly,band spacing and eccentricity respectively showed positive and negative correlation with crystallization temperature.These meaningful results shed light on regulating the architecture of banded crystals in polymer composites.展开更多
With the rapid increase in chip integration and power density,there is a growing need to develop advanced thermal interface materials for effective thermal management.Liquid metals with high thermal conductivity,excel...With the rapid increase in chip integration and power density,there is a growing need to develop advanced thermal interface materials for effective thermal management.Liquid metals with high thermal conductivity,excellent gap-filling capability and non-toxicity have received much attention.However,low-melting-point metals,such as galinstan and indium-bismuth-tin(EInBiSn) eutectic alloys,are prone to leaking,which limits their applications.In this study,In-Ga alloy composite thermal pads with a sandwich structure and a graphite film as an intermediate layer were prepared.The In-Ga alloy composition was adjusted so that these pads underwent partial phase change in the operating temperature range of the laptop CPU(50-100℃).This results in low thermal resistance and leakage prevention.The thermal resistance of the InGa5,InGa15 and InGa25 alloy thermal pads decreases to 7.3,4.1 and 2.66 K·mm^(2)·W^(-1),respectively,at a temperature and pressure of 100℃ and 50 psi.In a test measuring the actual cooling effect of the fabricated material on a CPU,the InGa 15 alloy thermal pad maintained the average CPU temperature at 90.1 ℃,significantly better than the EInBiSn thermal pad with an average CPU temperature of 94.1℃,and comparable to Galinstan,which had an average CPU temperature of 89.3℃.Due to their good heat dissipation and leak-proof properties,InGa alloy composite thermal pads are expected to become a new generation of thermal interface materials.展开更多
Background Epicardial adipose tissue(EAT)radiomics derived from cardiac computed tomography(CT)images may pr-ovide insights into EAT characteristics,which can further predict regression of left ventricular mass index(...Background Epicardial adipose tissue(EAT)radiomics derived from cardiac computed tomography(CT)images may pr-ovide insights into EAT characteristics,which can further predict regression of left ventricular mass index(LVMI)after transcath-eter aortic valve replacement(TAVR).This study aimed to develop and validate a radiomics nomogram based on pre-procedural EAT CT to predict inadequate LVMI regression following TAVR.Methods Inadequate LVMI regression was defined asΔLVMI%<15%at one-year post TAVR.Radiomics features from pre-procedural CT images were selected mainly by least absolute shrinkage and selection operator algorithm.The patients were ran-domly divided into the training and validation cohorts to establish and evaluate three feature classifier models based on the selec-ted features,using which the Radiomics scores(Radscores)were then calculated.A radiomics nomogram was constructed using independent risk factors and further assessed using area under the curve,calibration curve,and decision curve analysis.Results A total of 144 consecutive TAVR patients(42 patients with inadequate and 102 patients with adequate LVMI regres-sion)were randomly assigned to the training and validation cohorts(116 patients and 28 patients,respectively).A total of 1130 radiomics features from each patient yielded 6 features for the Radscore construction after selection,with logistic regression and support vector machine models favored.Subsequently,a nomogram based solely on the Radscore was constructed,with an area under the curve of 0.743 in the validation cohort,along with favorable decision curve analysis and calibration curves.Conclusions The developed radiomics nomogram,serving as a non-invasive tool,achieved satisfactory preoperative predic-tion of inadequate LVMI regression in TAVR patients,thereby facilitating clinical management.展开更多
This paper proposes second-order distributed algorithms over multi-agent networks to solve the convex optimization problem by utilizing the gradient tracking strategy, with convergence acceleration being achieved. Bot...This paper proposes second-order distributed algorithms over multi-agent networks to solve the convex optimization problem by utilizing the gradient tracking strategy, with convergence acceleration being achieved. Both the undirected and unbalanced directed graphs are considered, extending existing algorithms that primarily focus on undirected or balanced directed graphs. Our algorithms also have the advantage of abandoning the diminishing step-size strategy so that slow convergence can be avoided. Furthermore, the exact convergence to the optimal solution can be realized even under the constant step size adopted in this paper. Finally, two numerical examples are presented to show the convergence performance of our algorithms.展开更多
基金supported by the Natural Science Foundation of Gansu Province(No.22JR5RA118)the National Natural Science Foundation of China(Nos.12121005 and U1932138)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34010000)。
文摘The measurement of low-level radioactivity using high-purity germanium(HPGe)detectors is important in applications such as environmental background radiation,material screening,and rare decays.The dead layers,dead zones,aluminum shell thickness,and diameter of Ge crystals are the most influential factors affecting the performance of HPGe detectors;hence,precise modeling of the physical conditions of the detectors is highly desirable.In this study,the GEANT4 simulation framework with an optimized detector geometry adequately replicated the experimentally recorded spectrum.These detector simulations explored the idea of realizing a dead zone(an inactive volume)at the backend of an n-type coaxial Gecrystal.Using multigamma sources,the effect of true coincidence summing(TCS)on the full energy peak(FEP)efficiency calibration of an HPGe detector was investigated as a function of sample-to-detector distance.Good agreements between the simulated and experimental efficiencies as well as the simulated and analytically calculated summing coincidence correction coefficients were achieved.At a short distance between the source and detector,calculating the correction factors for a strong source posed challenges owing to significant deadtime and pile-up effects of the detection system.The described methodology can efficiently determine summing peak probabilities at short sample-to-detector distances.
基金Supported by National Natural Science Foundation of China,No.81973620Wenzhou Municipal Science and Technology Bureau,No.Y20220091.
文摘BACKGROUND The prevalence of addiction makes it a significant public health issue.Recently,transcranial magnetic stimulation(TMS)has garnered significant attention as a promising treatment for addiction.AIM To analyze development trends and research hotspots in TMS-based addiction treatment using a bibliometric approach.METHODS Articles on TMS-based addiction treatment from 2001 to 2023 were sourced from the Science Citation Index Expanded in the Web of Science Core Collection.CiteSpace software,VOSviewer,the"bibliometrix"R software package,and the bibliometric online analysis platform were used to analyze the current publication trends and hotspots.RESULTS Total 190 articles on TMS-based addiction treatment were identified,with clinical studies being the most prevalent.The United States led in both publication volume and international collaborations.Medical University of South Carolina and Zangen A were the most productive institution and author,respectively.Neurobiology,alcohol use disorder,and repetitive TMS were the most recent research hotspots.CONCLUSION Future research should focus on the neurobiological mechanisms underlying TMS-based addiction treatment.This study offers comprehensive insights and recommendations for advancing research on TMS-based addiction treatment.
基金Supported by the National Natural Science Foundation of China,No.82270916,No.81800748 and No.82371478the Third Affiliated Hospital of Anhui Medical University Basic and Clinical Collaborative Research Enhancement Program Cultivation Special Funding Project,No.2022sfy009.
文摘BACKGROUND Depression has become a global public health problem.In recent years,transcranial magnetic stimulation(TMS)has gained considerable attention as a noninvasive treatment for depression.AIM To investigate the research hotspots and trends in the field of TMS-based depression treatment from a bibliometric perspective.METHODS Using the Web of Science Core Collection,articles published between 2003 and 2022 on TMS-based depression treatment were retrieved from the science citation index expanded.The publication trends and research hotspots were analyzed using VOSviewer,CiteSpace,and the bibliometric online analysis platform.Regression analysis was performed using Microsoft Excel 2021 to predict publication growth trends.RESULTS We identified a total of 702 articles on TMS-based depression treatment with a predominance of clinical studies.Analysis of collaborative networks showed that the United States,the University of Toronto,and Daskalakis ZJ were identified as the most impactful country,institution,and researcher,respectively.In keyword burst analysis,it was found that theta burst stimulation(TBS),functional connectivity,and frequency were the most recent research hotspots.CONCLUSION TMS provides a novel therapeutic option for patients with treatment-resistant depression.Neuroimaging technology enables more precise TMS treatment,while the novel TMS modality,TBS,enhances both therapeutic efficacy and patient experience in TMS-based depression treatment.The integration of neuroimaging techniques with TBS represents a promising research direction for advancing TMS-based depression treatment.This study presents systematic information and recommendations to guide future research on TMS-based depression treatment.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFC2206003)。
文摘With the increasing accuracy requirements of satellite magnetic detection missions,reducing low-frequency noise has become a key focus of satellite magnetic cleanliness technology.Traditional satellite magnetic simulation methods have matured in static magnetic dipole simulations,but there is still significant room for optimization in the simulation and computation of low-frequency magnetic dipole models.This study employs the Gauss-Newton method and Fourier transform techniques for modeling and simulating low-frequency magnetic dipoles.Compared to the traditional particle swarm optimization(PSO)algorithm,this method achieves significant improvements,with errors reaching the order of10^(-13)%under noise-free conditions and maintaining an error level of less than 0.5%under 10%noise.Additionally,the use of Fourier transform and the Gauss-Newton method enables high-precision magnetic field frequency identification and rapid computation of the dipole position and magnetic moment,greatly enhancing the computational efficiency and accuracy of the model.
基金the National Key R&D Program of China(No.2018YFB0704200)the National Natural Science Foundation of China(Nos.52022061,51803192,52033005 and 51803139).
文摘Interfacial crystallization of polyoxymethylene/poly(butylene succinate)blends induced by the polyamide 6(PA6)fiber was investigated.Due to strong heterogeneous nucleating ability,dense nuclei were generated on the surface of the PA6 fiber,which compelled the growth of twisted lamellae perpendicular to the PA6 fiber.As a result,unique interfacial banded transcrystallization was formed,which is rarely found before.Crystallization temperature was dominant in determining the nucleation activity of the PA6 fiber,further affecting the architecture of banded transcrystallization.With the increase of crystallization temperature,the nucleation density decreased to give more growth space for the twisted lamellae around the fiber.The wave-like banded stripes were transformed into fan-like stripes.Accordingly,band spacing and eccentricity respectively showed positive and negative correlation with crystallization temperature.These meaningful results shed light on regulating the architecture of banded crystals in polymer composites.
基金financially supported by the National Natural Science Foundation of China (Nos.11204097 and U1530120)。
文摘With the rapid increase in chip integration and power density,there is a growing need to develop advanced thermal interface materials for effective thermal management.Liquid metals with high thermal conductivity,excellent gap-filling capability and non-toxicity have received much attention.However,low-melting-point metals,such as galinstan and indium-bismuth-tin(EInBiSn) eutectic alloys,are prone to leaking,which limits their applications.In this study,In-Ga alloy composite thermal pads with a sandwich structure and a graphite film as an intermediate layer were prepared.The In-Ga alloy composition was adjusted so that these pads underwent partial phase change in the operating temperature range of the laptop CPU(50-100℃).This results in low thermal resistance and leakage prevention.The thermal resistance of the InGa5,InGa15 and InGa25 alloy thermal pads decreases to 7.3,4.1 and 2.66 K·mm^(2)·W^(-1),respectively,at a temperature and pressure of 100℃ and 50 psi.In a test measuring the actual cooling effect of the fabricated material on a CPU,the InGa 15 alloy thermal pad maintained the average CPU temperature at 90.1 ℃,significantly better than the EInBiSn thermal pad with an average CPU temperature of 94.1℃,and comparable to Galinstan,which had an average CPU temperature of 89.3℃.Due to their good heat dissipation and leak-proof properties,InGa alloy composite thermal pads are expected to become a new generation of thermal interface materials.
基金supported by the National Natural Science Foundation of China (No.82170375 & No.8210 2129 & U23A20395)the 1·3·5 Project for Disciplines of Excellence from West China Hospital of Sichuan University (ZYGD23021)the Sichuan Science and Technology Program (No.2024NSFSC1714 & No.2024 NSFSC1716).
文摘Background Epicardial adipose tissue(EAT)radiomics derived from cardiac computed tomography(CT)images may pr-ovide insights into EAT characteristics,which can further predict regression of left ventricular mass index(LVMI)after transcath-eter aortic valve replacement(TAVR).This study aimed to develop and validate a radiomics nomogram based on pre-procedural EAT CT to predict inadequate LVMI regression following TAVR.Methods Inadequate LVMI regression was defined asΔLVMI%<15%at one-year post TAVR.Radiomics features from pre-procedural CT images were selected mainly by least absolute shrinkage and selection operator algorithm.The patients were ran-domly divided into the training and validation cohorts to establish and evaluate three feature classifier models based on the selec-ted features,using which the Radiomics scores(Radscores)were then calculated.A radiomics nomogram was constructed using independent risk factors and further assessed using area under the curve,calibration curve,and decision curve analysis.Results A total of 144 consecutive TAVR patients(42 patients with inadequate and 102 patients with adequate LVMI regres-sion)were randomly assigned to the training and validation cohorts(116 patients and 28 patients,respectively).A total of 1130 radiomics features from each patient yielded 6 features for the Radscore construction after selection,with logistic regression and support vector machine models favored.Subsequently,a nomogram based solely on the Radscore was constructed,with an area under the curve of 0.743 in the validation cohort,along with favorable decision curve analysis and calibration curves.Conclusions The developed radiomics nomogram,serving as a non-invasive tool,achieved satisfactory preoperative predic-tion of inadequate LVMI regression in TAVR patients,thereby facilitating clinical management.
基金supported by National Nature Science Foundation of China (Nos. 61663026, 62066026, 61963028 and 61866023)Jiangxi NSF (No. 20192BAB 207025)。
文摘This paper proposes second-order distributed algorithms over multi-agent networks to solve the convex optimization problem by utilizing the gradient tracking strategy, with convergence acceleration being achieved. Both the undirected and unbalanced directed graphs are considered, extending existing algorithms that primarily focus on undirected or balanced directed graphs. Our algorithms also have the advantage of abandoning the diminishing step-size strategy so that slow convergence can be avoided. Furthermore, the exact convergence to the optimal solution can be realized even under the constant step size adopted in this paper. Finally, two numerical examples are presented to show the convergence performance of our algorithms.
