The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient(ADC), cannot reveal microstructural changes in different locati...The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient(ADC), cannot reveal microstructural changes in different locations or the degree of infarction. This prospective observational study was reviewed and approved by the Institutional Review Board of Xiamen Second Hospital, China(approval No. 2014002).Diffusion kurtosis imaging(DKI) was used to detect 199 lesions in 156 patients with acute ischemic stroke(61 males and 95 females), mean age 63.15 ± 12.34 years. A total of 199 lesions were located in the periventricular white matter(n = 52), corpus callosum(n = 14), cerebellum(n = 29), basal ganglia and thalamus(n = 21), brainstem(n = 21) and gray-white matter junctions(n = 62). Percentage changes of apparent diffusion coefficient(ΔADC) and DKI-derived indices(fractional anisotropy [ΔFA], mean diffusivity [ΔMD], axial diffusivity [ΔD_a], radial diffusivity ΔDr, mean kurtosis [ΔMK], axial kurtosis [ΔK_a], and radial kurtosis [ΔK_r]) of each lesion were computed relative to the normal contralateral region. The results showed that(1) there was no significant difference in ΔADC, ΔMD, ΔD_a or ΔD_r among almost all locations.(2) There was significant difference in ΔMK among almost all locations(except basal ganglia and thalamus vs. brain stem; basal ganglia and thalamus vs. gray-white matter junctions; and brainstem vs. gray-white matter junctions.(3) The degree of change in diffusional kurtosis in descending order was as follows: corpus callosum > periventricular white matter > brainstem > gray-white matter junctions > basal ganglia and thalamus > cerebellum. In conclusion, DKI could reveal the differences in microstructure changes among various locations affected by acute ischemic stroke, and performed better than diffusivity among all groups.展开更多
Early detection and diagnosis of breast cancer are essential for successful treatment. Currently mammography and ultrasound are the basic imaging techniques for the detection and localization of breast tumors. The low...Early detection and diagnosis of breast cancer are essential for successful treatment. Currently mammography and ultrasound are the basic imaging techniques for the detection and localization of breast tumors. The low sensitivity and specificity of these imaging tools resulted in a demand for new imaging modalities and breast magnetic resonance imaging(MRI) has become increasingly important in the detection and delineation of breast cancer in daily practice. However, the clinical benefits of the use of pre-operative MRI in women with newly diagnosed breast cancer is still a matter of debate. The main additional diagnostic value of MRI relies on specific situations such as detecting multifocal, multicentric or contralateral disease unrecognized on conventional assessment(particularly in patients diagnosed with invasive lobular carcinoma), assessing the response to neoadjuvant chemotherapy, detection of cancer in dense breast tissue, recognition of an occult primary breast cancer in patients presenting with cancer metastasis in axillary lymph nodes, among others. Nevertheless, the development of new MRI technolo-gies such as diffusion-weighted imaging, proton spectroscopy and higher field strength 7.0 T imaging offer a new perspective in providing additional information in breast abnormalities. We conducted an expert literature review on the value of breast MRI in diagnosing and staging breast cancer, as well as the future potentials of new MRI technologies.展开更多
This work presents a different approach to twin primes, an approach from the perspective of the Tesla numbers and gives a refresh and new observation of twin primes that could lead us to an answer to the Twin Prime Co...This work presents a different approach to twin primes, an approach from the perspective of the Tesla numbers and gives a refresh and new observation of twin primes that could lead us to an answer to the Twin Prime Conjecture problem. We expose a peculiar relation between twin primes and the generation of prime numbers with Tesla numbers. Tesla numbers seem to be present in so many domains like time, vibration and frequency [1], and the space between twin primes is not the exception. Let us say that twin primes are more than just prime numbers plus 2 or minus 2, and Tesla numbers are more involved with twin primes than we think, and hopefully, this approach give us a better understanding of the distribution of the twin pairs.展开更多
This research work relates the surface of a square and the area circumscribed by a circle, resulting in a value called Nikola Tesla constant. This constant starts with the calculation of the areas of the square and th...This research work relates the surface of a square and the area circumscribed by a circle, resulting in a value called Nikola Tesla constant. This constant starts with the calculation of the areas of the square and the inscribed circle, giving a ratio of 9/40 and from which a residual area of the area proportions of the geometric figures described is obtained. Plotting smooth curves, particularly those in round shapes, can be represented efficiently with the use of Nikola Tesla constant, reducing complex mathematical calculus.展开更多
The integration of 7 Tesla magnetic resonance imaging(7 T MRI)in adult patients has marked a revolutionary stride in radiology.In this article we explore the feasibility of 7 T MRI in paediatric practice,emphasizing i...The integration of 7 Tesla magnetic resonance imaging(7 T MRI)in adult patients has marked a revolutionary stride in radiology.In this article we explore the feasibility of 7 T MRI in paediatric practice,emphasizing its feasibility,applications,challenges,and safety considerations.The heightened resolution and tissue contrast of 7 T MRI offer unprecedented diagnostic accuracy,particularly in neuroimaging.Applications range from neuro-oncology to neonatal brain imaging,showcasing its efficacy in detecting subtle structural abnormalities and providing enhanced insights into neurological conditions.Despite the promise,challenges such as high cost,discomfort,and safety concerns necessitate careful consideration.Research suggests that,with precautions,7 T MRI is feasible in paediatrics,yet ongoing studies and safety assessments are imperative.展开更多
Background: Non-uniformity in signal intensity occurs commonly in magnetic resonance (MR) imaging, which may pose substantial problems when using a 3T scanner. Therefore, image non-uniformity correction is usually app...Background: Non-uniformity in signal intensity occurs commonly in magnetic resonance (MR) imaging, which may pose substantial problems when using a 3T scanner. Therefore, image non-uniformity correction is usually applied. Purpose: To compare the correction effects of the phased-array uniformity enhancement (PURE), a calibration-based image non-uniformity correction method, among three different software versions in 3T Gd-EOB-DTPA-enhanced MR imaging. Material and Methods: Hepatobiliary-phase images of a total of 120 patients who underwent Gd-EOB-DTPA-enhanced MR imaging on the same 3T scanner were analyzed retrospectively. Forty patients each were examined using three software versions (DV25, DV25.1, and DV26). The effects of PURE were compared by visual assessment, histogram analysis of liver signal intensity, evaluation of the spatial distribution of correction effects, and evaluation of quantitative indices of liver parenchymal enhancement. Results: The visual assessment indicated the highest uniformity of PURE-corrected images for DV26, followed by DV25 and DV25.1. Histogram analysis of corrected images demonstrated significantly larger variations in liver signal for DV25.1 than for the other two versions. Although PURE caused a relative increase in pixel values for central and lateral regions, such effects were weaker for DV25.1 than for the other two versions. In the evaluation of quantitative indices of liver parenchymal enhancement, the liver-to-muscle ratio (LMR) was significantly higher for the corrected images than for the uncorrected images, but the liver-to-spleen ratio (LSR) showed no significant differences. For corrected images, the LMR was significantly higher for DV25 and DV26 than for DV25.1, but the LSR showed no significant differences among the three versions. Conclusion: There were differences in the effects of PURE among the three software versions in 3T Gd-EOB-DTPA-enhanced MR imaging. Even if the non-uniformity correction method has the same brand name, correction effects may differ dep展开更多
The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporat...The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.展开更多
The so-called ORC(Organic Rankine Cycle)heat recovery technology has attracted much attention with regard to medium and low temperature waste heat recovery.In the present study,it is applied to a Tesla turbine.At the ...The so-called ORC(Organic Rankine Cycle)heat recovery technology has attracted much attention with regard to medium and low temperature waste heat recovery.In the present study,it is applied to a Tesla turbine.At the same time,the effects of the disc speed,diameter and inter-disc gap on the internal flow field and output power of the turbine are also investigated by means of CFD(Computational Fluid Dynamics)numerical simulation,by which the pressure,velocity,and output efficiency of the internal flow field are obtained under different internal and external conditions.The highest efficiency(66.4%)is obtained for a number of nozzles equal to 4,a disk thickness of 1 mm,and a gap of 1 mm between the disks.The results of the study serve as a theoretical basis for the structural design and optimization of Tesla turbines.展开更多
基金supported by the Science and Technology Planned Project from Xiamen Science and Technology Bureau,China,No.3502Z20154065(to LHZ)the Joint Project for Xiamen Key Diseases from Xiamen Science and Technology Bureau,China,No.3502Z20149032(to GG)
文摘The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient(ADC), cannot reveal microstructural changes in different locations or the degree of infarction. This prospective observational study was reviewed and approved by the Institutional Review Board of Xiamen Second Hospital, China(approval No. 2014002).Diffusion kurtosis imaging(DKI) was used to detect 199 lesions in 156 patients with acute ischemic stroke(61 males and 95 females), mean age 63.15 ± 12.34 years. A total of 199 lesions were located in the periventricular white matter(n = 52), corpus callosum(n = 14), cerebellum(n = 29), basal ganglia and thalamus(n = 21), brainstem(n = 21) and gray-white matter junctions(n = 62). Percentage changes of apparent diffusion coefficient(ΔADC) and DKI-derived indices(fractional anisotropy [ΔFA], mean diffusivity [ΔMD], axial diffusivity [ΔD_a], radial diffusivity ΔDr, mean kurtosis [ΔMK], axial kurtosis [ΔK_a], and radial kurtosis [ΔK_r]) of each lesion were computed relative to the normal contralateral region. The results showed that(1) there was no significant difference in ΔADC, ΔMD, ΔD_a or ΔD_r among almost all locations.(2) There was significant difference in ΔMK among almost all locations(except basal ganglia and thalamus vs. brain stem; basal ganglia and thalamus vs. gray-white matter junctions; and brainstem vs. gray-white matter junctions.(3) The degree of change in diffusional kurtosis in descending order was as follows: corpus callosum > periventricular white matter > brainstem > gray-white matter junctions > basal ganglia and thalamus > cerebellum. In conclusion, DKI could reveal the differences in microstructure changes among various locations affected by acute ischemic stroke, and performed better than diffusivity among all groups.
文摘Early detection and diagnosis of breast cancer are essential for successful treatment. Currently mammography and ultrasound are the basic imaging techniques for the detection and localization of breast tumors. The low sensitivity and specificity of these imaging tools resulted in a demand for new imaging modalities and breast magnetic resonance imaging(MRI) has become increasingly important in the detection and delineation of breast cancer in daily practice. However, the clinical benefits of the use of pre-operative MRI in women with newly diagnosed breast cancer is still a matter of debate. The main additional diagnostic value of MRI relies on specific situations such as detecting multifocal, multicentric or contralateral disease unrecognized on conventional assessment(particularly in patients diagnosed with invasive lobular carcinoma), assessing the response to neoadjuvant chemotherapy, detection of cancer in dense breast tissue, recognition of an occult primary breast cancer in patients presenting with cancer metastasis in axillary lymph nodes, among others. Nevertheless, the development of new MRI technolo-gies such as diffusion-weighted imaging, proton spectroscopy and higher field strength 7.0 T imaging offer a new perspective in providing additional information in breast abnormalities. We conducted an expert literature review on the value of breast MRI in diagnosing and staging breast cancer, as well as the future potentials of new MRI technologies.
文摘This work presents a different approach to twin primes, an approach from the perspective of the Tesla numbers and gives a refresh and new observation of twin primes that could lead us to an answer to the Twin Prime Conjecture problem. We expose a peculiar relation between twin primes and the generation of prime numbers with Tesla numbers. Tesla numbers seem to be present in so many domains like time, vibration and frequency [1], and the space between twin primes is not the exception. Let us say that twin primes are more than just prime numbers plus 2 or minus 2, and Tesla numbers are more involved with twin primes than we think, and hopefully, this approach give us a better understanding of the distribution of the twin pairs.
文摘This research work relates the surface of a square and the area circumscribed by a circle, resulting in a value called Nikola Tesla constant. This constant starts with the calculation of the areas of the square and the inscribed circle, giving a ratio of 9/40 and from which a residual area of the area proportions of the geometric figures described is obtained. Plotting smooth curves, particularly those in round shapes, can be represented efficiently with the use of Nikola Tesla constant, reducing complex mathematical calculus.
文摘The integration of 7 Tesla magnetic resonance imaging(7 T MRI)in adult patients has marked a revolutionary stride in radiology.In this article we explore the feasibility of 7 T MRI in paediatric practice,emphasizing its feasibility,applications,challenges,and safety considerations.The heightened resolution and tissue contrast of 7 T MRI offer unprecedented diagnostic accuracy,particularly in neuroimaging.Applications range from neuro-oncology to neonatal brain imaging,showcasing its efficacy in detecting subtle structural abnormalities and providing enhanced insights into neurological conditions.Despite the promise,challenges such as high cost,discomfort,and safety concerns necessitate careful consideration.Research suggests that,with precautions,7 T MRI is feasible in paediatrics,yet ongoing studies and safety assessments are imperative.
文摘Background: Non-uniformity in signal intensity occurs commonly in magnetic resonance (MR) imaging, which may pose substantial problems when using a 3T scanner. Therefore, image non-uniformity correction is usually applied. Purpose: To compare the correction effects of the phased-array uniformity enhancement (PURE), a calibration-based image non-uniformity correction method, among three different software versions in 3T Gd-EOB-DTPA-enhanced MR imaging. Material and Methods: Hepatobiliary-phase images of a total of 120 patients who underwent Gd-EOB-DTPA-enhanced MR imaging on the same 3T scanner were analyzed retrospectively. Forty patients each were examined using three software versions (DV25, DV25.1, and DV26). The effects of PURE were compared by visual assessment, histogram analysis of liver signal intensity, evaluation of the spatial distribution of correction effects, and evaluation of quantitative indices of liver parenchymal enhancement. Results: The visual assessment indicated the highest uniformity of PURE-corrected images for DV26, followed by DV25 and DV25.1. Histogram analysis of corrected images demonstrated significantly larger variations in liver signal for DV25.1 than for the other two versions. Although PURE caused a relative increase in pixel values for central and lateral regions, such effects were weaker for DV25.1 than for the other two versions. In the evaluation of quantitative indices of liver parenchymal enhancement, the liver-to-muscle ratio (LMR) was significantly higher for the corrected images than for the uncorrected images, but the liver-to-spleen ratio (LSR) showed no significant differences. For corrected images, the LMR was significantly higher for DV25 and DV26 than for DV25.1, but the LSR showed no significant differences among the three versions. Conclusion: There were differences in the effects of PURE among the three software versions in 3T Gd-EOB-DTPA-enhanced MR imaging. Even if the non-uniformity correction method has the same brand name, correction effects may differ dep
文摘星基增强系统(Satellite Based Augmentation System,SBAS)的电文格式公开,为防止SBAS服务遭受生成式欺骗攻击,国际民航组织积极推进SBAS认证服务标准的制定.本文面向北斗星基增强系统(BeiDou SatelliteBased Augmentation System,BDSBAS)阐述了基于中国商用密码算法的椭圆曲线数字签名(Elliptic Curve Digital Signature Algorithm,ECDSA)电文认证方案与时间效应流丢失容错(Time Efficient Stream Loss-tolerant Authentication,TESLA)电文认证方案,设计了BDSBAS认证电文,依据空中密钥管理OTAR(Over The Air Rekeying)的策略制定了OTAR电文(OTAR Message Type,OMT)与播发方案.通过蒙特卡洛OTAR仿真器开展仿真,对不同OTAR电文接收时间进行分析,本文设计的方案与国外方案对比结果有明显的提升,有效的减少了接收机完成认证使用SBAS增强服务的时间,对BDSBAS电文认证服务提供一定参考与建议.
基金supported by the National Key R&D Program of China(No.2018YFA0108100)the National Natural Science Foundation of China(No.62104009)Experiments on human sweat were conducted in accordance with the approved protocol from the institutional review board at Peking University Third Hospital,Beijing,China(No.M2021610).
文摘The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.
基金the National Natural Science Foundation of China(No.51876114)Shanghai Engineering Research Center of Marine Renewable Energy(Grant No.19DZ2254800).
文摘The so-called ORC(Organic Rankine Cycle)heat recovery technology has attracted much attention with regard to medium and low temperature waste heat recovery.In the present study,it is applied to a Tesla turbine.At the same time,the effects of the disc speed,diameter and inter-disc gap on the internal flow field and output power of the turbine are also investigated by means of CFD(Computational Fluid Dynamics)numerical simulation,by which the pressure,velocity,and output efficiency of the internal flow field are obtained under different internal and external conditions.The highest efficiency(66.4%)is obtained for a number of nozzles equal to 4,a disk thickness of 1 mm,and a gap of 1 mm between the disks.The results of the study serve as a theoretical basis for the structural design and optimization of Tesla turbines.
