广义Gamma分布弱湍流环境含指向误差串行中继水下无线光通信系统误码性能分析

鉴于目前普遍选用的水下弱湍流模型无法准确拟合实测数据的缺陷,选取经实验测试验证的广义Gamma分布来表征海洋弱湍流,以期合理评估受湍流等因素影响的水下无线光通信系统的误码性能。提出一种包含广义Gamma分布弱湍流、零/非零视轴指向误差以及无衰落信道冲激响应隐路径损耗和多径效应的混合衰落信道模型,据此推导混合衰落串行中继无线光通信系统平均误码率的数学闭型表达;通过数值仿真验证所推导的误码率理论表达式的准确性,并考察不同系统核心参数对误码率的影响。研究结果表明:串行中继节点的引入可有效提高系统的误码性能,以零视轴指向误差、最终传输距离达45 m、误码率需求10-3为例,引入1至3个串行中继节点后,系统从一开始的无法工作,变为所需的发射功率分别降低至24 dBm、12 dBm和6 dBm;而光源初始发散角增大导致的无衰落信道冲激响应时延扩展,即符号间干扰,则会严重降低此性能改善。

一类折叠Gamma分布的尖峰厚尾性质及应用

组合分布思想的出现及扩展为研究现实数据分布提供了优良方案。鉴于许多数据的尖峰后尾特征,文章从Gamma分布出发,构造了具有尖峰厚尾性质的折叠Gamma分布,进而讨论了折叠Gamma分布的性质,并在Newton-Raphson算法下给出了分布参数的矩估计和极大似然估计,同时以数值模拟证明了估计的可行性,最后以实际数据对比研究折叠Gamma分布和正态分布的拟合效果。结果表明:折叠Gamma分布能更好地拟合尖峰厚尾数据,且其拟合效果随着数据样本量的增大而变好。

基于GAMMA软件二次开发的地表形变监测系统

InSAR技术具有大范围、高精度、全天时、全天候的优点,已被广泛地应用于地表形变监测与高程获取。GAMMA软件具有支持数据源丰富、处理功能全面、结果精度可靠和效率高等优势,是当前国际上常用的InSAR数据处理软件。但该软件采用命令行交互,操作命令繁杂、对专业要求程度高,不易于非专业用户使用。针对以上问题,本文利用界面友好、开源的QGIS对GAMMA进行二次开发。结合GAMMA提供的py_gamma库和QGIS提供的py_QGIS API接口,采用模块化设计、算法并行优化等技术,开发了一套界面化InSAR形变监测系统,并以西藏沃达地区106景哨兵1号数据进行处理试验,从软件性能和处理结果方面证明了基于QGIS和GAMMA二次开发的可行性和可靠性。相关内容可为命令行用户界面软件转图形化用户界面提供参考。

基于最大图像熵Gamma校正估计的图像特征点检测和匹配方法

提出一种基于最大图像熵Gamma校正估计的图像特征点检测和匹配方法。通过预处理算法来增强图像的对比度,将其应用于图像特征点的检测和匹配。在预处理阶段,首先采用对数函数对图像进行归一化,根据设定的阈值将图像分为明亮和黑暗分量;然后分别对两个分量自适应地选择不同的参数进行Gamma校正,并且确定使其熵最大化的校正参数为每个分量的最佳参数;最后将上述参数应用于Gamma校正生成对应原始图像明亮和黑暗区域的矫正图,并进行融合生成增强的图像。对预处理完的图像进行特征点检测和匹配实验。研究结果表明:所提出的算法相较于未处理算法、HE和自适应Gamma算法,特征点检测后的匹配数量在欠曝光图像上分别提升85.7%、26.4%和15.2%,在过曝光图像上分别提升59.4%、12.2%和103.8%。匹配效果也有较明显提升。

基于Gamma混合模型的出租车落客行为

为了更好地理解枢纽送站坪出租车落客行为,提高落客区域通行效率,提出基于Gamma混合模型的出租车落客决策模型.应用精确的出租车轨迹数据,将出租车停车时间分解为主动停车时间、被迫停车时间和落客时间,基于被迫停车时间分析构建等待耐性混合分布模型,模型验证结果与真实数据相吻合.在此基础上,以潜在乘客耐心分布、停车位置、期望停车位和行程时间为落客决策模型的核心指标,提取相关因子为解释变量,以是否落客为被解释变量,构建二元面板Logit模型,并对模型进行检验.结果表明,乘客耐心对车辆落客起着决定性的作用,落客决策模型预测准确率超过81%,表明该模型能够较好地预测出租车落客行为,为研究缓堵策略提供基础.

基于间断性Gamma校正的粘连蚕茧分割方法研究

目前,蚕茧分割计数研究主要针对大小几乎完全相同的蚕茧,难以应对大小差异较大的情况。针对上述问题,采用图像增强的方法提取蚕茧表面并进行蚕茧的粘连分割。首先,将原图直接转化为灰度图像进行腐蚀处理,通过Gamma校正使得图像灰度值收缩;其次,通过限制对比度自适应直方图均衡化(CLAHE)方法提高蚕茧图像与其背景区域的灰度差,使其进一步分离;再利用高斯滤波和腐蚀方法平滑并收缩蚕茧图像,根据亮度数据进行第二次Gamma校正以调整对比度;最后,通过二值化处理统计连通域个数得出蚕茧数量。实验结果表明,所提方法针对大小蚕茧分割适应力较强,平均准确率高达99%。

Gamma-Gamma信道下基于并行交织极化码的误码性能研究

为了降低大气湍流引起的衰落影响,同时减少长片误码干扰,提出一种基于并行交织极化码(polar code)的编码方法。通过蒙特卡洛模拟Gamma-Gamma分布的随机数构建大气湍流信道,以成对差错概率(pairwise error probability, PEP)和极化谱确定极化信道的误差概率上限,采用乘积距离准则最小化差错概率,建立了并行交织的设计准则。对极化码在湍流信道中的误码率(bit error rate, BER)性能进行了评估,仿真结果表明,基于极化码的并行交织方法获得了一个量级的误码性能提升,在信噪比为5 dB时,误码率从5.11×10-6降低为2.13×10-7,有效缓解了湍流引起的长片误码问题。实验验证了所提准则的可靠性和适用性。

Gamma3髓内钉在股骨粗隆间骨折手术治疗中的应用效果评价

目的探讨Gamma3髓内钉应用于股骨粗隆间骨折手术治疗中的效果。方法选择2020年1月—2022年12月丹阳市中医院收治的82例股骨粗隆间骨折患者为研究对象,以随机数表法分为对照组(n=41,给予抗旋型股骨近端髓内钉手术治疗)与观察组(n=41,给予Gamma3髓内钉手术治疗),比较两组患者的手术治疗相关指标、髋关节功能与并发症。结果两组患者的手术用时、手术总失血量对比,差异无统计学意义(P均>0.05)。观察组患者的住院时间(12.14±1.16)d、术后负重时间(5.63±1.07)周、骨折愈合时间(7.32±1.18)周均短于对照组,差异有统计学意义(t=12.535、9.884、6.992,P均<0.05)。与术前比较,两组患者术后1、3、6个月时的Harris评分均升高,差异有统计学意义(P均<0.05);但各时间段组间比较,差异无统计学意义(P均>0.05)。两组髋关节功能优良率、并发症发生率对比,差异无统计学意义(P均>0.05)。结论Gamma3髓内钉与抗旋型股骨近端髓内钉治疗股骨粗隆间骨折的效果、安全性均相当,但Gamma3髓内钉能加快患者术后功能恢复。

Genetic Enhancement of Indigenous Cowpea with Gamma-Ray Induced Trait Variation

Production of cowpea (Vigna unguiculata (L.) Walp.), a staple legume crop in Sub-Saharan Africa, faces challenges due to biotic and abiotic constraints. Induced mutagenesis was deployed to create genetic variation in two cowpea varieties (KVX396-4-5-2D and Moussa local). The radio-sensitivity tests led to determe the lethal dose 50 (LD50) corresponding to 230 Gy and 220 Gy for KVX396-4-5-2D and Moussa local varieties, respectively. Dried seeds (M0) of each variety were gamma-ray irradiated with LD50 − 50, LD50 and LD50 + 50. M1 seeds were advanced to generate M2, M3 and M4 mutants using the single-seed-descent method. M4 mutant lines were evaluated in rain-fed conditions using a randomized complete block design to assess phenotypic differences. Data on seven qualitative and eleven quantitative traits were collected. The results indicated that the mutation induced variability in three qualitative traits: in KVX 396-4-5-2D mutant lines, with flower and seed color frequencies at 2.61% and 0.56% respectively, and pod dehiscence at a frequency of 0.24%. While in Moussa local mutants, a pod color changed at a frequency of 17%. ANOVA results revealed significant differences between mutants of both varieties for all quantitative traits, including photosynthetic parameters. Positive correlations were observed between leaf diameter and 100-seed weight, and between branch number and 100-seed weight. Hierarchical clustering revealed three clusters among KVX 396-4-5-2D mutants and six clusters among Moussa local mutants. Early maturity and high foliage were induced traits in Cluster 3 of KVX 396-4-5-2D mutants while high hundred-seed weight was induced in Cluster 6 of Moussa local mutants.

改进Gamma变换的遥感影像阴影补偿方法

影像阴影是遥感影像应用与解译的重要干扰项,为了提高阴影补偿精度,更真实地还原遥感影像上地物特征信息,提出一种基于提取同质区域的改进Gamma变换的阴影补偿方法.选取了两张具有不同地物特征的遥感影像作为实验区,首先对实验区影像进行蓝光抑制;其次,通过膨胀运算和腐蚀运算求取阴影区域与非阴影同质区域,构造实验区所需要的结构元素;最后,针对同质区域通过Gamma变换对遥感影像进行阴影补偿,与Retinex算法和局部补偿算法进行精度比较.实验结果表明,该方法在每个颜色通道的平均梯度都要优于另外两种算法,从而验证了该文方法对提升遥感影像阴影补偿精度的有效性,为提高遥感影像阴影补偿精度提供了一种新思路.

Meta-analysis of the clinical efficacy of the Gamma3 nail vs Gamma3U-blade system in the treatment of intertrochanteric fractures

BACKGROUND The traditional Gamma3 nail is a mainstream treatment for femoral intertrochanteric fractures.Literature reports that the Gamma3U-blade system can increase the stability of the Gamma3 nail and reduce complication incidence.However,comparative studies between the Gamma3U-blade and Gamma3 systems are limited;hence,this meta-analysis was performed to explore the clinical efficacy of these two surgical methods.AIM To investigate the clinical efficacy of Gamma3 and Gamma3 U-blade for intertrochanteric fractures.METHODS A computerized search for Chinese and English literature published from 2010 to 2022 was conducted in PubMed,Cochrane,CNKI,Wanfang,and VIP databases.The search keywords were gamma 3,gamma 3 U blade,and intertrochanteric fracture.Additionally,literature tracking was performed on the references of published literature.The data were analyzed using Revman 5.3 software.Two individuals checked the inputs for accuracy.Continuous variables were described using mean difference and standard deviation,and outcome effect sizes were expressed using ratio OR and 95%confidence interval(CI).High heterogeneity was considered at(P<0.05,I2>50%),moderate heterogeneity at I2 from 25%to 50%,and low heterogeneity at(P≥0.05,I2<50%).RESULTS Following a comprehensive literature search,review,and analysis,six articles were selected for inclusion in this study.This selection comprised five articles in English and one in Chinese,with publication years spanning from 2016 to 2022.The study with the largest sample size,conducted by Seungbae in 2021,included a total of 304 cases.Statistical analysis:A total of 1063 patients were included in this meta-analysis.The main outcome indicators were:Surgical time:The Gamma3U blade system had a longer surgical time compared to Gamma3 nails(P=0.006,I2=76%).Tip-apex distance:No statistical significance or heterogeneity was observed(P=0.65,I2=0%).Harris Hip score:No statistical significance was found,and low heterogeneity was detected(P=0.26,I2=22%).Union time:No statistical significance was found,and high heterogeneity was detected(P=0.05,I2=75%).CONCLUSION Our study indicated that the Gamma3 system reduces operative time compared to the Gamma3 U-blade system in treating intertrochanteric fractures.Both surgical methods proved to be safe and effective for this patient group.These findings may offer valuable insights and guidance for future surgical protocols in hip fracture patients.

Probability Laws Derived from the Gamma Function

Several densities or probability laws of continuous random variables derive from the Euler Gamma function. These laws form the basis of sampling theory, namely hypothesis testing and estimation. Namely the gamma, beta, and Student law, through the chi-square law and the normal law are all distributions resulting from applications of Euleur functions.

Analysis of Progressively Type-Ⅱ Inverted Generalized Gamma Censored Data and Its Engineering Application

A novel inverted generalized gamma(IGG)distribution,proposed for data modelling with an upside-down bathtub hazard rate,is considered.In many real-world practical situations,when a researcher wants to conduct a comparative study of the life testing of items based on cost and duration of testing,censoring strategies are frequently used.From this point of view,in the presence of censored data compiled from the most well-known progressively Type-Ⅱ censoring technique,this study examines different parameters of the IGG distribution.From a classical point of view,the likelihood and product of spacing estimation methods are considered.Observed Fisher information and the deltamethod are used to obtain the approximate confidence intervals for any unknown parametric function of the suggestedmodel.In the Bayesian paradigm,the same traditional inferential approaches are used to estimate all unknown subjects.Markov-Chain with Monte-Carlo steps are considered to approximate all Bayes’findings.Extensive numerical comparisons are presented to examine the performance of the proposed methodologies using various criteria of accuracy.Further,using several optimality criteria,the optimumprogressive censoring design is suggested.To highlight how the proposed estimators can be used in practice and to verify the flexibility of the proposed model,we analyze the failure times of twenty mechanical components of a diesel engine.

Gamma Approximation Based Multi-Antenna Covert Communication Detection

Covert communication technology makes wireless communication more secure,but it also provides more opportunities for illegal users to transmit harmful information.In order to detect the illegal covert communication of the lawbreakers in real time for subsequent processing,this paper proposes a Gamma approximation-based detection method for multi-antenna covert communication systems.Specifically,the Gamma approximation property is used to calculate the miss detection rate and false alarm rate of the monitor firstly.Then the optimization problem to minimize the sum of the missed detection rate and the false alarm rate is proposed.The optimal detection threshold and the minimum error detection probability are solved according to the properties of the Lambert W function.Finally,simulation results are given to demonstrate the effectiveness of the proposed method.

Evaluation of Interferon-Gamma Release Assay Testing and Tuberculin Skin Test for Early Diagnosis of Tuberculosis in Children and Adolescents

Background: This study aimed to evaluate the diagnostic value of interferon-γ release assay (IGRA), a sensitive microbiological diagnostic method, in children and adolescents with suspected tuberculosis in a country with a high burden of tuberculosis. Method: This study included 581 children and adolescents aged 4 - 19 years who were suspected of having tuberculosis, were latently infected with Mycobacterium tuberculosis, and had received at least one dose of BCG vaccine between April 17, 2019, and February 24, 2021. The study evaluated the TST results of 106 patients who had a positive Quantiferon test and were suspected of having tuberculosis. Results: The study included 581 patients aged between 4 and 19 years. Of these, 106 patients tested positive for the Quantiferon test, while 19 were indeterminate and 456 were negative. The Quantiferon test positivity rate was 18.24%. Among the 106 QFT-Plus-positive cases, 23 patients also tested positive for TST. The difference in distribution was found to be statistically significant. Conclusion: The QFT-Plus test is considered an alternative to TST and other microbiological diagnostic methods for early tuberculosis diagnosis, particularly in children and adolescents.

Clinical efficacy of Gamma Knife® combined with transarterial chemoembolization and immunotherapy in the treatment of primary liver cancer

BACKGROUND This study was designed to investigate the clinical efficacy and safety of Gamma Knife®combined with transarterial chemoembolization(TACE)and immunotherapy in the treatment of primary liver cancer.AIM To investigate the clinical efficacy and safety of Gamma Knife®combined with TACE and immune-targeted therapy in the treatment of primary liver cancer.METHODS Clinical data from 51 patients with primary liver cancer admitted to our hospital between May 2018 and October 2022 were retrospectively collected.All patients underwent Gamma Knife®treatment combined with TACE and immunotherapy.The clinical efficacy,changes in liver function,overall survival(OS),and progression-free survival(PFS)of patients with different treatment responses were evaluated,and adverse reactions were recorded.RESULTS The last follow-up for this study was conducted on October 31,2023.Clinical evaluation of the 51 patients with primary liver cancer revealed a partial response(PR)in 27 patients,accounting for 52.94%(27/51);stable disease(SD)in 16 patients,accounting for 31.37%(16/51);and progressive disease(PD)in 8 patients,accounting for 15.69%(8/51).The objective response rate was 52.94%,and the disease control rate was 84.31%.Alanine aminotransferase,aspartate aminotransferase,lactate dehydrogenase,and alpha-fetoprotein isoform levels decreased after treatment compared with pretreatment(all P=0.000).The median OS was 26 months[95%confidence interval(95%CI):19.946-32.054]in the PR group and 19 months(95%CI:14.156-23.125)in the SD+PD group,with a statistically significant difference(P=0.015).The median PFS was 20 months(95%CI:18.441-34.559)in the PR group and 12 months(95%CI:8.745-13.425)in the SD+PD group,with a statistically significant difference(P=0.002).Common adverse reactions during treatment included nausea and vomiting(39.22%),thrombocytopenia(27.45%),and leukopenia(25.49%),with no treatment-related deaths reported.CONCLUSION Gamma Knife®combined with TACE and immune-targeted therapy is safe and effective in the treatment of primary liver cancer and has a good effect on improving the clinical benefit rate and liver function of patients.

Feasibility study of the photonuclear reaction cross section of medical radioisotopes using a laser Compton scattering gamma source

In recent years,the gap between the supply and demand of medical radioisotopes has increased,necessitating new methods for producing medical radioisotopes.Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes.However,the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes.In this study,the entire process of the generation,decay,and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gamma-ray spectrometer.Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source(SLEGS),the feasibility of this measurement of production cross section for surveyed medi-cal radioisotopes was simulated,and specific solutions for measuring medical radioisotopes with ultra-low production cross sections were provided.The feasibility of this method for high-precision measurements of the reaction cross section of medical radioisotopes was demonstrated.

基于Gamma-Gamma湍流信道下的卷积码性能研究

为了研究不同码型的卷积码在水下湍流信道中的误码率(BER)性能,采用接受-拒绝采样模拟湍流信道乘性干扰,并选择二进制相移键控(BPSK)调制方式,建立Gamma-Gamma湍流信道通信系统仿真模型。仿真结果表明:在不同强度的湍流信道中,采用卷积码编码均能提升系统的BER性能;卷积码的码率越小,系统BER性能提升越显著;随着信噪比(SNR)增大,记忆深度越长,系统BER下降速度越快;采用软译码比采用硬译码时增益至少提升2.82 d B;卷积码的解码不仅受当前信息的影响,还与之前的码元信息有关。

Cortico-striatal gamma oscillations are modulated by dopamine D3 receptors in dyskinetic rats

Long-term levodopa administration can lead to the development of levodopa-induced dyskinesia.Gamma oscillations are a widely recognized hallmark of abnormal neural electrical activity in levodopa-induced dyskinesia.Currently,studies have reported increased oscillation power in cases of levodopa-induced dyskinesia.However,little is known about how the other electrophysiological parameters of gamma oscillations are altered in levodopa-induced dyskinesia.Furthermore,the role of the dopamine D3 receptor,which is implicated in levodopa-induced dyskinesia,in movement disorder-related changes in neural oscillations is unclear.We found that the cortico-striatal functional connectivity of beta oscillations was enhanced in a model of Parkinson’s disease.Furthermore,levodopa application enhanced cortical gamma oscillations in cortico-striatal projections and cortical gamma aperiodic components,as well as bidirectional primary motor cortex(M1)↔dorsolateral striatum gamma flow.Administration of PD128907(a selective dopamine D3 receptor agonist)induced dyskinesia and excessive gamma oscillations with a bidirectional M1↔dorsolateral striatum flow.However,administration of PG01037(a selective dopamine D3 receptor antagonist)attenuated dyskinesia,suppressed gamma oscillations and cortical gamma aperiodic components,and decreased gamma causality in the M1→dorsolateral striatum direction.These findings suggest that the dopamine D3 receptor plays a role in dyskinesia-related oscillatory activity,and that it has potential as a therapeutic target for levodopa-induced dyskinesia.

基于Gamma和时变Markov模型的天然气管道剩余寿命预测

基于Gamma和时变Markov模型,对天然气管道的剩余寿命进行深入研究。采用Gamma随机过程建立管道的退化模型,以腐蚀深度为指标,并应用SY/T6151一2009标准划分了不同腐蚀状态。为更准确地模拟管道退化过程中的实际情况,引入时变转移概率矩阵,考虑随时间变化的状态迁移。以APILX52级别钢制管路为对象,通过监测数据预测剩余寿命,并验证模型的准确性。结果表明,与传统的Markov模型相比,该方法能够更精准地预测管道寿命的减少或延长。