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Dosimetric Effects Due to Inter-Observer Variability of Organ Contouring When Utilizing a Knowledge-Based Planning System for Prostate Cancer
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作者 Han Liu Christopher Amaloo +1 位作者 Benjamin Sintay David Wiant 《International Journal of Medical Physics, Clinical Engineering and Radiation Oncology》 2021年第2期47-58,共12页
<strong>Purpose:</strong><span style="font-family:;" "=""><span style="font-family:Verdana;"> Radiotherapy is a widely accepted standard of care for early-sta... <strong>Purpose:</strong><span style="font-family:;" "=""><span style="font-family:Verdana;"> Radiotherapy is a widely accepted standard of care for early-stage prostate cancer, and it is believed that the plan quality and treatment outcome are associated with contour accuracy of both the target and organs-at-risk (OAR). The purposes of this study are to 1) assess geometric and dosimetric uncertainties due to inter-observer contour variabilities and 2) evaluate the effectiveness of geometric indicators to predict target dosimetry in prostate radiotherapy. </span><b><span style="font-family:Verdana;">Methods:</span></b><span style="font-family:Verdana;"> Twenty prostate patients were selected for this retrospective study. Five experienced clinicians created unique structure sets containing prostate, seminal vesicles, bladder, and rectum for each patient. A fully automated script and knowledge-based planning routine were utilized to create standardized and unbiased plans that could be used to evaluate changes in isodose distributions due to inter-observer variability in structure segmentation. Plans were created on a “gold-standard” structure set, as well as on each of the user-defined structure sets. </span><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"> Inter-observer variability of contours during structure segmentation was very low for clearly defined organs such as the bladder but increased for organs without well-defined borders (prostate, seminal vesicles, and rectum). For plans generated with the user-defined structure sets, strong/moderate correlations were observed between the geometric indicators for target structure agreement and target coverage for both low-risk and intermediate-risk patient groups, while OAR indicators showed no correlation to final dosimetry. </span><b><span style="font-family:Verdana;">Conclusions:</span></b><span style="font-family:Verdana;"> Target delineation is crucial in order to maintain adequate dosimetric coverage regardless of the associated inter-observer uncertainties in OAR contours that had a limited impact upon final dosimetry.</span></span> 展开更多
关键词 inter-observer variability of Organ Contouring Knowledge-Based Treat-ment Planning Prostate Radiotherapy
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Inter-Observer Variability in the Interpretation of 68Ga-PSMA PET-CT Scan according to PROMISE Criteria
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作者 Amina Nasir Muhammad Numair Younis +3 位作者 Sadia Adnan Tahira Yasmin Ismat Fatima Abubaker Shahid 《Advances in Molecular Imaging》 2022年第1期1-13,共13页
Aims & Objectives: Aim of the study was to evaluate inter-observer variability in interpretation of Gallium-68 labeled Prostate Specific Membrane Antigen sub-type 11 (68Ga-PSMA-11) Positron Emission Tomography-Com... Aims & Objectives: Aim of the study was to evaluate inter-observer variability in interpretation of Gallium-68 labeled Prostate Specific Membrane Antigen sub-type 11 (68Ga-PSMA-11) Positron Emission Tomography-Computed Tomography PET_CT scan according to Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE) criteria. Method and Materials: Forty-four consecutive patients of prostate cancer were prospectively studied between the duration of January 2021 to June 2021 at Institute of Nuclear Medicine and Oncology (INMOL), Lahore. All PET-CT scans were assessed by a researcher and 3 nuclear physicians and divided into two groups, interpreted in two phases. In the first phase, each group independently evaluated the scans while in the second phase, a consensus meeting was held and all the cases with discordance were discussed. Cohen’s Kappa test was used to measure interobserver variability with the cut-off of K’s alpha Results: The study showed 41 out of 44 scans with positive PSMA findings while 03 scans were negative for any PSMA avid disease. In the first phase of image analysis, the level of agreement was slight in T stage (Kappa = 0.068, p = 0.65), moderate in the miN stage (Kappa = 0.46, p = 0.02) and substantial in miM stage (Kappa = 0.77, p ≤ 0.001) was seen. For PSMA score, overall agreement was substantial agreement (Kappa = 0.64, p Conclusion: Remarkable inter-observer agreement was seen in PROMISE criteria. 展开更多
关键词 68Ga-PSMA PET-CT PROMISE Criteria PSMA Score inter-observer variability
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Inter-Observer Variability in the Detection and Interpretation of Chest X-Ray Anomalies in Adults in an Endemic Tuberculosis Area 被引量:1
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作者 Boniface Moifo Eric Walter Pefura-Yone +4 位作者 Georges Nguefack-Tsague Marie Laure Gharingam Jean Roger Moulion Tapouh André-Pascal Kengne Samuel Nko’o Amvene 《Open Journal of Medical Imaging》 2015年第3期143-149,共7页
Purpose: To assess the inter-observer agreement in reading adults chest radiographs (CXR) and determine the effectiveness of observers in radiographic diagnosis of pulmonary tuberculosis (PTB) in a tuberculosis endemi... Purpose: To assess the inter-observer agreement in reading adults chest radiographs (CXR) and determine the effectiveness of observers in radiographic diagnosis of pulmonary tuberculosis (PTB) in a tuberculosis endemic area. Methods: A quasi-observational study was conducted in the Pneumology Department of Yaounde Jamot Hospital (Cameroon) from January to March 2014. This included six observers (two chest physicians, two radiologists, two end-training residents in medical imaging) and 47 frontal CXRs (4 of diffuse interstitial lung disease, 6 normal, 7 of lung cancers, 7 of bacterial pneumonia, 23 of PTB). The sample size was calculated on the basis of an expected 0.47 Kappa with a spread of 0.13 (α = 5%, CI = 95%) for six observers and five diagnostic items. The analysis of concordance was focused on the detection of nodules, cavitary lesions, pleural effusion, adenomegaly and diagnosis of PTB and lung cancer. These intervals of kappa coefficient were considered: discordance (0.81). Results: The average score for the detection of caverns was the highest (58.3%) followed by that of the correct diagnosis of tuberculosis (49.3%). Pneumologists had the highest proportions of correct diagnosis of tuberculosis (69.6% and 73.9%) and better inter-observer agreement (k = 0.71) for PTB diagnosis. Observers were more in agreement for the detection of nodules (0.32 - 0.74), adenomegalies (0.43 - 0.69), and for the diagnosis of cancer (0.22 - 1) than for the diagnosis of tuberculosis (0.19 - 0.71). Disagreements were more frequent for the detection of pleural effusions (-0.08 - 0.73). Conclusion: The inter-observer agreement varies with the type of lesions and diagnosis. Pneumologists were most effective for the diagnosis of pulmonary tuberculosis. Observers were more in agreement for the detection of nodules and the diagnosis of cancer than for the diagnosis of pulmonary tuberculosis. 展开更多
关键词 inter-observer variability CONCORDANCE Pulmonary TUBERCULOSIS NODULES Caverns Lung Cancer CHEST Radiography KAPPA
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Responses of Annual Variability of Vegetation NPP to Climate Variables Using Satellite Techniques in Gadarif State, Sudan
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作者 Anwar Mohamedelhassan Bo Zhang +1 位作者 Abdelrahim E. Jahelnabi Eman M. Elhassan 《Journal of Geographic Information System》 2024年第2期136-147,共12页
Plants play an essential role in matter and energy transformations and are key messengers in the carbon and energy cycle. Net primary productivity (NPP) reflects the capability of plants to transform solar energy into... Plants play an essential role in matter and energy transformations and are key messengers in the carbon and energy cycle. Net primary productivity (NPP) reflects the capability of plants to transform solar energy into photosynthesis. It is very sensible for factors affecting on vegetation variability such as climate, soils, plant characteristics and human activities. So, it can be used as an indicator of actual and potential trend of vegetation. In this study we used the actual NPP which was derived from MODIS to assess the response of NPP to climate variables in Gadarif State, from 2000 to 2010. The correlations between NPP and climate variables (temperature and precipitation) are calculated using Pearson’s Correlation Coefficient and ordinary least squares regression. The main results show the following 1) the correlation Coefficient between NPP and mean annual temperature is Somewhat negative for Feshaga, Rahd, Gadarif and Galabat areas and weakly negative in Faw area;2) the correlation Coefficient between NPP and annual total precipitation is weakly negative in Faw, Rahd and Galabat areas and somewhat negative in Galabat and Rahd areas. This study demonstrated that the correlation analysis between NPP and climate variables (precipitation and temperature) gives reliably result of NPP responses to climate variables that is clearly in a very large scale of study area. 展开更多
关键词 Climate Variables MODIS NPP Climate Change Correlation Coefficient Gadarif State Remote Sensing GIS Applications
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A Technical Note: Inter-Observer and Inter-Modality Variability of Cone-Beam Computed Tomography (CBCT) and Ultrasound (US) in Stereotactic Body Radiotherapy for Kidney Cancer
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作者 Ronnie W. K. Leung Matthew Y. P. Wong +8 位作者 Venus W. Y. Lee Steven K. T. Cheung Aray K. L. Wong Hollis S. L. Luk Francesca K. L. Ng Gilbert M. L. Law Frankle K. H. Lee W. H. Mui Dennis Y. K. Ngar 《International Journal of Medical Physics, Clinical Engineering and Radiation Oncology》 2017年第4期392-400,共9页
Introduction: To investigate the inter-observer and inter-modality variabilities of two imaging guided equipments—cone-beam computed tomography (CBCT) and ultrasound (US) in kidney stereotactic body radiotherapy. Met... Introduction: To investigate the inter-observer and inter-modality variabilities of two imaging guided equipments—cone-beam computed tomography (CBCT) and ultrasound (US) in kidney stereotactic body radiotherapy. Methods: A renal metastasis case implanted with three gold anchor fiducial markers was firstly scanned by US to acquire a 3-dimension US image and followed by 4-dimension CBCT in every fraction. Seven observers retrospectively registered the pre-treatment images with the corresponding reference images based on the gold markers. Registration uncertainty of the observers between two imaging modalities was evaluated. Results: The uncertainties over whole treatment course in CBCT were 0.88 mm, 1.94 mm and 0.86 mm in lateral, longitudinal and vertical directions respectively;while 0.8 mm, 0.97 mm and 1.36 mm were found in US. Conclusion: The greatest uncertainty was found in longitudinal direction in CBCT due to the fact that the respiration motion is the most rigorous in cranial-caudal direction. In US, since the probe was hold almost in upright position, the strong echo in vertical direction was attributed to the greatest uncertainty for such direction. 展开更多
关键词 inter-observer Inter-Modality variability CBCT US Kidney SBRT
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Prediction of microstructure evolution of ZK61 alloy during hot spinning by internal state variable model 被引量:2
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作者 Jin-qi PAN Wen-cong ZHANG +3 位作者 Jian-lei YANG Song-hui WANG Yong WU Huan LI 《Transactions of Nonferrous Metals Society of China》 2025年第1期126-142,共17页
An internal state variable(ISV)model was established according to the experimental results of hot plane strain compression(PSC)to predict the microstructure evolution during hot spinning of ZK61 alloy.The effects of t... An internal state variable(ISV)model was established according to the experimental results of hot plane strain compression(PSC)to predict the microstructure evolution during hot spinning of ZK61 alloy.The effects of the internal variables were considered in this ISV model,and the parameters were optimized by genetic algorithm.After validation,the ISV model was used to simulate the evolution of grain size(GS)and dynamic recrystallization(DRX)fraction during hot spinning via Abaqus and its subroutine Vumat.By comparing the simulated results with the experimental results,the application of the ISV model was proven to be reliable.Meanwhile,the strength of the thin-walled spun ZK61 tube increased from 303 to 334 MPa due to grain refinement by DRX and texture strengthening.Besides,some ultrafine grains(0.5μm)that played an important role in mechanical properties were formed due to the proliferation,movement,and entanglement of dislocations during the spinning process. 展开更多
关键词 internal state variable model hot spinning ZK61 alloy finite element simulation texture evolution
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A Significant Transition of Antarctic Sea Ice Variability in Response to the Shoaling of the Circumpolar Deep Water 被引量:1
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作者 Ruonan CHEN Xiao-Yi YANG Dongxiao WANG 《Advances in Atmospheric Sciences》 2025年第12期2499-2517,共19页
As a crucial component of the Earth’s climate system,Antarctic sea ice has demonstrated significant variability over the satellite era.Here,we identify a remarkable decadal transition in the total Antarctic Sea Ice E... As a crucial component of the Earth’s climate system,Antarctic sea ice has demonstrated significant variability over the satellite era.Here,we identify a remarkable decadal transition in the total Antarctic Sea Ice Extent(SIE).The stage from 1979 to 2006 is characterized by high-frequency(i.e.,seasonal to interannual)temporal variability in SIE and zonal asymmetry in Sea Ice Concentration(SIC),which is primarily under the control of the Amundsen Sea Low(ASL).After 2007,however,sea ice changes exhibit a more spatially homogeneous pattern in SIC and a more temporally long-lasting mode in SIE.Further analysis reveals that sea ice-ocean interaction plays a major role in the low-frequency(i.e.,multiannual)variability of Antarctic sea ice from 2007−22.The related physical process is inferred to manifest as a strong coupling between the surface and the subsurface ocean layers,involving enhanced vertical convection and the downward delivery of the surface anomalies related to ice melting and freezing processes,thus maintaining the SIE anomalies for a longer time.Furthermore,this process mainly occurs in the Amundsen-Bellingshausen Sea(ABS)sector,and the weakened subsurface ocean stratification is the key factor triggering the coupling process in this region.We find that the Circumpolar Deep Water(CDW)over the ABS sector continued to shoal before 2007 and remained stable thereafter.It is speculated that the shoaling of the CDW may be a possible driver leading to the weakening of the subsurface stratification. 展开更多
关键词 Antarctic sea ice low-frequency variability coupling process ocean stratification CDW ice-ocean interaction
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Increase in the variability of terrestrial carbon uptake in response to enhanced future ENSO modulation
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作者 Younong Li Li Dan +2 位作者 Jing Peng Qidong Yang Fuqiang Yang 《Atmospheric and Oceanic Science Letters》 2025年第1期32-38,共7页
El Niño-Southern Oscillation(ENSO)is a major driver of climate change in middle and low latitudes and thus strongly influences the terrestrial carbon cycle through land-air interaction.Both the ENSO modulation an... El Niño-Southern Oscillation(ENSO)is a major driver of climate change in middle and low latitudes and thus strongly influences the terrestrial carbon cycle through land-air interaction.Both the ENSO modulation and carbon flux variability are projected to increase in the future,but their connection still needs further investigation.To investigate the impact of future ENSO modulation on carbon flux variability,this study used 10 CMIP6 earth system models to analyze ENSO modulation and carbon flux variability in middle and low latitudes,and their relationship,under different scenarios simulated by CMIP6 models.The results show a high consistency in the simulations,with both ENSO modulation and carbon flux variability showing an increasing trend in the future.The higher the emissions scenario,especially SSP5-8.5 compared to SSP2-4.5,the greater the increase in variability.Carbon flux variability in the middle and low latitudes under SSP2-4.5 increases by 30.9%compared to historical levels during 1951-2000,while under SSP5-8.5 it increases by 58.2%.Further analysis suggests that ENSO influences mid-and low-latitude carbon flux variability primarily through temperature.This occurrence may potentially be attributed to the increased responsiveness of gross primary productivity towards regional temperature fluctuations,combined with the intensified influence of ENSO on land surface temperatures. 展开更多
关键词 Carbon variability ENSO modulation CMIP6 models
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Optimizing Fine-Tuning in Quantized Language Models:An In-Depth Analysis of Key Variables
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作者 Ao Shen Zhiquan Lai +1 位作者 Dongsheng Li Xiaoyu Hu 《Computers, Materials & Continua》 SCIE EI 2025年第1期307-325,共19页
Large-scale Language Models(LLMs)have achieved significant breakthroughs in Natural Language Processing(NLP),driven by the pre-training and fine-tuning paradigm.While this approach allows models to specialize in speci... Large-scale Language Models(LLMs)have achieved significant breakthroughs in Natural Language Processing(NLP),driven by the pre-training and fine-tuning paradigm.While this approach allows models to specialize in specific tasks with reduced training costs,the substantial memory requirements during fine-tuning present a barrier to broader deployment.Parameter-Efficient Fine-Tuning(PEFT)techniques,such as Low-Rank Adaptation(LoRA),and parameter quantization methods have emerged as solutions to address these challenges by optimizing memory usage and computational efficiency.Among these,QLoRA,which combines PEFT and quantization,has demonstrated notable success in reducing memory footprints during fine-tuning,prompting the development of various QLoRA variants.Despite these advancements,the quantitative impact of key variables on the fine-tuning performance of quantized LLMs remains underexplored.This study presents a comprehensive analysis of these key variables,focusing on their influence across different layer types and depths within LLM architectures.Our investigation uncovers several critical findings:(1)Larger layers,such as MLP layers,can maintain performance despite reductions in adapter rank,while smaller layers,like self-attention layers,aremore sensitive to such changes;(2)The effectiveness of balancing factors depends more on specific values rather than layer type or depth;(3)In quantization-aware fine-tuning,larger layers can effectively utilize smaller adapters,whereas smaller layers struggle to do so.These insights suggest that layer type is a more significant determinant of fine-tuning success than layer depth when optimizing quantized LLMs.Moreover,for the same discount of trainable parameters,reducing the trainable parameters in a larger layer is more effective in preserving fine-tuning accuracy than in a smaller one.This study provides valuable guidance for more efficient fine-tuning strategies and opens avenues for further research into optimizing LLM fine-tuning in resource-constrained environments. 展开更多
关键词 Large-scale Language Model Parameter-Efficient Fine-Tuning parameter quantization key variable trainable parameters experimental analysis
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Interannual variability of boreal summer intraseasonal oscillation over the northwestern Pacific influenced by the Pacific Meridional Mode
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作者 Haoyu Zhou Pang-Chi Hsu +1 位作者 Lin Chen Yitian Qian 《Atmospheric and Oceanic Science Letters》 2025年第1期6-11,共6页
During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the s... During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the subtropical Northwestern Pacific(10°-20°N,130°E-175°W).The former is well-documented and considered to be influenced by the ENSO,while the latter has received comparatively less attention and is likely influenced by the Pacific Meridional Mode(PMM),as suggested by partial correlation analysis results.To elucidate the physical processes responsible for the enhanced(weakened)intraseasonal convection over the subtropical northwestern Pacific during warm(cold)PMM years,the authors employed a moisture budget analysis.The findings reveal that during warm PMM years,there is an increase in summer-mean moisture over the subtropical northwestern Pacific.This increase interacts with intensified vertical motion perturbations in the region,leading to greater vertical moisture advection in the lower troposphere and consequently resulting in convective instability.Such a process is pivotal in amplifying intraseasonal convection anomalies.The observational findings were further verified by model experiments forced by PMM-like sea surface temperature patterns. 展开更多
关键词 Boreal summer intraseasonal oscillation Interannual variability Pacific Meridional Mode Moisture budget analysis
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Assessment of Genetic Variability and Inter-Relationship for Yield Attributing Traits in Maize (Zea mays L.) Genotypes in White Nile State, Sudan
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作者 Sara Mohammed Abdalla Khalid Abdalla Osman +1 位作者 Abd Elwahab Abdalla Dafaalla Soheap Abdalrahman Yousif 《Agricultural Sciences》 2025年第2期280-289,共10页
Maize is an important source of calories and protein in human lives in many countries of the world and is the main staple food in Africa, particularly in eastern Africa. In the Sudan, the low yield of maize was mainly... Maize is an important source of calories and protein in human lives in many countries of the world and is the main staple food in Africa, particularly in eastern Africa. In the Sudan, the low yield of maize was mainly due to the use of low yielding landraces. It is necessary to carry out breeding programs that deal with the production of high yielding, adaptable new varieties. Therefore, this study aimed to estimate genetic variability, heritability, genotypic performance and interrelationships among the traits. Ten maize genotypes evaluated at White Nile Research Station Farm, Kosti, of the Agricultural Research Corporation (ARC), Wad Medani Sudan were planted in a randomized complete block design with three replications during the two seasons of 2021 and 2022. Most evaluated genotypes exhibited a wide and significant variation in the 11 measured traits. Genotypic coefficient of variation and genetic advance were recorded for days to 50% tasseling, ear diameter (cm), number of grains per row and grain yield (t/ha) in both seasons. High heritability and genetic advance were recorded for grain yield, ear length, ear height, plant height, number of rows per ear, ear weight, days to 50% tasseling, 100-grain weight and days to 50% silking. Moreover, there was a highly significant and positive correlation of grain yield with number of rows per ear (r = 0.479), ear length (r = 0.381), 100-grain weight (r = 0.344) and days to 50% tasseling (r = 0.214). The highest yielding five genotypes across the seasons were TZCOM1/ZDPSYN (4.2 t/ha), EEPVAH-3 (4.2 t/ha), F2TWLY131228 (4.1 t/ha), PVA SYN6F2 (3.9 t/ha) and EEPVAH-9 (3.8 t/ha) these were needed to check the adaptability, stability and to test major maize growing areas to make sound recommendations for release. 展开更多
关键词 Genetic variability HERITABILITY Correlation MAIZE YIELD
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Equilibrium Strategies in M/M/1 Retrial Queues with Variable Service Rate
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作者 LIU Yuanyuan YAN Zhaozeng YANG Qin 《应用概率统计》 北大核心 2025年第3期448-466,共19页
We consider a single server constant retrial queue,in which a state-dependent service policy is used to control the service rate.Customer arrival follows Poisson process,while service time and retrial time are exponen... We consider a single server constant retrial queue,in which a state-dependent service policy is used to control the service rate.Customer arrival follows Poisson process,while service time and retrial time are exponential distributions.Whenever the server is available,it admits the retrial customers into service based on a first-come first-served rule.The service rate adjusts in real-time based on the retrial queue length.An iterative algorithm is proposed to numerically solve the personal optimal problem in the fully observable scenario.Furthermore,we investigate the impact of parameters on the social optimal threshold.The effectiveness of the results is illustrated by two examples. 展开更多
关键词 variable service rate retrial queues real-time adaptability equilibrium strategies ALGORITHM
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Gamma-Ray-Induced Genetic Variability for Yield Traits in M4 Generation in Upland Rice
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作者 Habibata Tinta Valentin Stanislas Edgar Traoré +5 位作者 Minimassom Philippe Nikiéma Arlette Wend-Yida Yasmine Kaboré Siébou Palé Hamidou Traoré Mahamadou Sawadogo Djibril Yonli 《Agricultural Sciences》 2025年第2期240-255,共16页
Varietal deficiencies of upland rice lead to a low paddy grain yield. The aim of this study was to mutagenesis upland rice varieties to improve their agronomic performance. Seeds of varieties FKR45N and FKR47N were th... Varietal deficiencies of upland rice lead to a low paddy grain yield. The aim of this study was to mutagenesis upland rice varieties to improve their agronomic performance. Seeds of varieties FKR45N and FKR47N were therefore irradiated with doses 300, 350 and 400 Gy. The irradiated seeds were sown and the panicles of the M1 plants were individually harvested, and then were advanced to M4 using the “one panicle - one progeny” method. The agronomic performance of M4 lines was compared to that of their parent. The gamma ray mutagenesis has induced significant variability in five yield components, i.e., plant height, main panicle length, total numbers of tillers and productive tillers and paddy grain yield between mutant lines. The highest variabilities were shown for the total number of tillers and the number of productive tillers as well as FKR45N (CV% = 40 % and 36%) and FKR47N (CV% = 31% and 30%) mutant lines. Principal component analysis led to rank the mutant lines from each variety in three clusters. The Pearson correlation showed that the paddy grain yield was significantly and positively correlated with the number of productive tillers (r = 0.61) and plant height (r = 0.66) for FKR47N mutant lines, and these correlation coefficients were r = 0.52 and r = 0.51 for FKR45N mutant lines, respectively. Gamma-ray irradiation also induced an earliness of 50% flowering of 62 days after sowing (DAS) in two FKR45N mutant lines and 67 DAS in one of KR47N mutant lines. The paddy grain yield was improved by 120% and 20% in two FKR45N and FKR47N mutant lines, respectively. A dwarf FKR45N mutant line with an early flowering of 67 DAS and a paddy grain yield (2.34 t ha−1) was generated. These results suggested that any positive increase in the six quantitative traits will increase the paddy grain yield. 展开更多
关键词 Upland Rice MUTAGENESIS Genetic variability Agronomic Performance
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Variable stiffness design optimization of fiber-reinforced composite laminates with regular and irregular holes considering fiber continuity for additive manufacturing 被引量:1
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作者 Yi LIU Zunyi DUAN +6 位作者 Chunping ZHOU Yuan SI Chenxi GUAN Yi XIONG Bin XU Jun YAN Jihong ZHU 《Chinese Journal of Aeronautics》 2025年第3期334-354,共21页
Fiber-reinforced composites are an ideal material for the lightweight design of aerospace structures. Especially in recent years, with the rapid development of composite additive manufacturing technology, the design o... Fiber-reinforced composites are an ideal material for the lightweight design of aerospace structures. Especially in recent years, with the rapid development of composite additive manufacturing technology, the design optimization of variable stiffness of fiber-reinforced composite laminates has attracted widespread attention from scholars and industry. In these aerospace composite structures, numerous cutout panels and shells serve as access points for maintaining electrical, fuel, and hydraulic systems. The traditional fiber-reinforced composite laminate subtractive drilling manufacturing inevitably faces the problems of interlayer delamination, fiber fracture, and burr of the laminate. Continuous fiber additive manufacturing technology offers the potential for integrated design optimization and manufacturing with high structural performance. Considering the integration of design and manufacturability in continuous fiber additive manufacturing, the paper proposes linear and nonlinear filtering strategies based on the Normal Distribution Fiber Optimization (NDFO) material interpolation scheme to overcome the challenge of discrete fiber optimization results, which are difficult to apply directly to continuous fiber additive manufacturing. With minimizing structural compliance as the objective function, the proposed approach provides a strategy to achieve continuity of discrete fiber paths in the variable stiffness design optimization of composite laminates with regular and irregular holes. In the variable stiffness design optimization model, the number of candidate fiber laying angles in the NDFO material interpolation scheme is considered as design variable. The sensitivity information of structural compliance with respect to the number of candidate fiber laying angles is obtained using the analytical sensitivity analysis method. Based on the proposed variable stiffness design optimization method for complex perforated composite laminates, the numerical examples consider the variable stiffness design optimization of typical non-perforated and perforated composite laminates with circular, square, and irregular holes, and systematically discuss the number of candidate discrete fiber laying angles, discrete fiber continuous filtering strategies, and filter radius on structural compliance, continuity, and manufacturability. The optimized discrete fiber angles of variable stiffness laminates are converted into continuous fiber laying paths using a streamlined process for continuous fiber additive manufacturing. Meanwhile, the optimized non-perforated and perforated MBB beams after discrete fiber continuous treatment, are manufactured using continuous fiber co-extrusion additive manufacturing technology to verify the effectiveness of the variable stiffness fiber optimization framework proposed in this paper. 展开更多
关键词 Variable stiffness composite laminates Discrete material interpolation scheme Normal distribution fiber optimization Discrete fiber continuous filtering strategy Additive manufacturing of composite laminates
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Equivalent Conditions of Complete Convergence for Weighted Sums of Sequences of i.i.d.Random Variables under Sublinear Expectations
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作者 XU Mingzhou CHENG Kun 《应用概率统计》 北大核心 2025年第3期339-352,共14页
The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the... The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the equivalent conditions of complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space.The results complement the corresponding results in probability space to those for sequences of independent,identically distributed random variables under sublinear expectation space. 展开更多
关键词 complete convergence weighted sums i.i.d.random variables sublinear expectation
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Micro-mechanical damage simulation of 2.5D woven variable thickness composites
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作者 Nan WANG Haitao CUI +3 位作者 Hongjian ZHANG Yaoming FU Gangjin HUANG Shuangqi LYU 《Chinese Journal of Aeronautics》 2025年第7期168-184,共17页
With the application of 2.5D Woven Variable Thickness Composites(2.5DWVTC)in aviation and other fields,the issue of strength failure in this composite type has become a focal point.First,a three-step modeling approach... With the application of 2.5D Woven Variable Thickness Composites(2.5DWVTC)in aviation and other fields,the issue of strength failure in this composite type has become a focal point.First,a three-step modeling approach is proposed to rapidly construct full-scale meso-finite element models for Outer Reduction Yarn Woven Composites(ORYWC)and Inner Reduction Yarn Woven Composites(IRYWC).Then,six independent damage variables are identified:yarn fiber tension/compression,yarn matrix tension/compression,and resin matrix tension/compression.These variables are utilized to establish the constitutive equation of woven composites,considering the coupling effects of microscopic damage.Finally,combined with the Hashin failure criterion and von Mises failure criterion,the strength prediction model is implemented in ANSYS using APDL language to simulate the strength failure process of 2.5DWVTC.The results show that the predicted stiffness and strength values of various parts of ORYWC and IRYWC are in good agreement with the relevant test results. 展开更多
关键词 Constitutive equation 2.5D woven variable thickness composites Damage variables Finite element models Modeling approach Strength prediction model
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Complete f-Moment Convergence for Sung’s Type Weighted Sums of Negatively Superadditive Dependent Random Variables
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作者 HU Xueping WANG Liuliu +1 位作者 HU Ke XU Zhonghao 《应用概率统计》 北大核心 2025年第4期585-601,共17页
In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergen... In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergence of NSD random variables.We establish and improve a general result on the complete f-moment convergence for Sung’s type randomly weighted sums of NSD random variables under some general assumptions.As an application,we show the complete consistency for the randomly weighted estimator in a nonparametric regression model based on NSD errors. 展开更多
关键词 Marcinkiewicz-Zygmund inequality Rosenthal-type inequality Sung’s type randomly weighted sums negatively superadditive dependent random variables complete f-moment convergence
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Dominant Modes of Spring Drought Variability in Southern China During 1979-2022 and the Associated Drivers
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作者 ZHOU Jia-yu QIU Wen-tian +2 位作者 ZHAO Qing-hong CHEN Xi DENG Kai-qiang 《Journal of Tropical Meteorology》 2025年第4期331-340,共10页
Utilizing the Standardized Precipitation Evapotranspiration Index(SPEI)and ERA5 reanalysis data,this study investigates the variability of spring drought in southern China from 1979 to 2022 and its associated drivers.... Utilizing the Standardized Precipitation Evapotranspiration Index(SPEI)and ERA5 reanalysis data,this study investigates the variability of spring drought in southern China from 1979 to 2022 and its associated drivers.The results indicate that southern China experienced interdecadal changes in SPEI over the past several decades,which can be concluded that drought severity intensified from 1979 to 2010,whereas a transition shift towards increased wetness occurred from 2010 to 2022.The first Empirical Orthogonal Function(EOF1)mode of SPEI variability in southern China accounts for 44.37%of the total variance,reflecting a uniform variation of SPEI across the region.In contrast,the second Empirical Orthogonal Function(EOF2),which explains 24.41%of the total variance,reveals a west-east dipole pattern in SPEI variability.Further analysis indicates that the positive phase of EOF1 is primarily driven by warm sea surface temperature anomalies(SSTAs)in the tropical eastern Pacific.These anomalies induce an anomalous anticyclone over the Philippine Sea,enhancing water vapor transport to southern China during spring.The positive phase of EOF2 is jointly influenced by warm SSTAs in the tropical Indian Ocean and the central Pacific;the latter induces anticyclonic anomalies over the Philippine Sea,which enhance water vapor transport from the western Pacific and increase precipitation in the eastern part of southern China.However,the warm SSTAs in the tropical Indian Ocean trigger an anomalous anticyclone over South Asia,inhibiting water vapor transport from the Bay of Bengal to the western part of southern China and thus reducing precipitation there. 展开更多
关键词 drought variability dominant modes southern China SPRING
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Mood alteration and heart rate variability in patients with cancer on treatment
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作者 Yun-Chen Chang Wei-Nung Liu +1 位作者 Felicia Lin Gen-Min Lin 《World Journal of Cardiology》 2025年第6期1-4,共4页
In this article,Deng and Song showed compelling evidence on the connection between heart rate variability(HRV)alterations and cancer in 127 cancer patients compared with healthy reference individuals,highlighting auto... In this article,Deng and Song showed compelling evidence on the connection between heart rate variability(HRV)alterations and cancer in 127 cancer patients compared with healthy reference individuals,highlighting autonomic nervous system dysfunction as a significant physiological manifestation in cancer patients.We discussed that the reduced HRV may be associated with cancer treatments,e.g.,operation,chemotherapy and pain control and psychological response such as depression and anxiety related to the affected cancer.A management such as medicine to mood disturbances related to cancer has been shown a benefit to improve HRV in cancer patients. 展开更多
关键词 CANCER CHEMOTHERAPY Heart rate variability Mental stress HEART
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Influence of ambient geochemical and microbiological variables on the bacterial diversity in a cold seep ecosystem in North Indian Ocean
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作者 Delcy R.Nazareth Maria Judith Gonsalves Nitisha Sangodkar 《Geoscience Frontiers》 2025年第3期153-163,共11页
Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at... Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at these sites.One such site in the cold seep ecosystem of Krishna-Godavari basin(K-G basin)along the east coast of India,discovered in Feb 2018 at a depth of 1800 m was assessed for its bacterial diversity.The seep bacterial communities were dominated by phylum Proteobacteria(57%),Firmicutes(16%)and unclassified species belonging to the family Helicobacteriaceae.The surface sediments of the seep had maximum OTUs(operational taxonomic units)(2.27×10^(3))with a Shannon alpha diversity index of 8.06.In general,environmental parameters like total organic carbon(p<0.01),sulfate(p<0.001),sulfide(p<0.05)and methane(p<0.01)were responsible for shaping the bacterial community of the cold seep ecosystem in the K-G Basin.Environmental parameters play a significant role in changing the bacterial diversity richness between different cold seep environments in the oceans. 展开更多
关键词 Sediments Environmental variables PROTEOBACTERIA Cold seep ecosystem Organic matter
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