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Article ; Online: Improved statistical models for the relationship between riparian vegetation and river flow in arid environments: Implications for flow management.

Zhang, Yichi

2023 Volume 874, Page(s) 162487

Abstract: Riparian vegetation (RV) provides critical ecosystem services but has been degraded worldwide due to river flow change. Quantitative relationships between RV and river flow are essential for understanding RV developments and managing flow to conserve RV. ...

Abstract	Riparian vegetation (RV) provides critical ecosystem services but has been degraded worldwide due to river flow change. Quantitative relationships between RV and river flow are essential for understanding RV developments and managing flow to conserve RV. Based on the improved statistical model framework that incorporates previous RV conditions into explanatory variables to estimate later RV conditions, this study quantified the RV-flow relationships on the annual scale in the arid Ejina Delta through regression analysis coupled with the normalized difference vegetation index (NDVI) and hydrological data during 2002-2020. The median of NDVIs over the April-October growing season (SMN) was used to indicate annual vegetation conditions, and annual RV cover was derived using a dynamic SMN threshold (0.077-0.084) based on its better vegetation conditions than surrounding deserts. The water year was determined as September-August based on the defoliation time and lag time of the groundwater response to river flow. The results showed that (1) the RV cover approximately expanded from 1619 to 2914 km
Language	English
Publishing date	2023-02-27
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	121506-1
ISSN	1879-1026 ; 0048-9697
ISSN (online)	1879-1026
ISSN	0048-9697
DOI	10.1016/j.scitotenv.2023.162487
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Article ; Online: Effect of river channel planar complexity on riparian vegetation-river flow relationships in arid environments.

Zhang, Yichi

The Science of the total environment

2023 Volume 912, Page(s) 168988

Abstract: Understanding how changes in channel form affect the relationships between riparian vegetation and river flow is critical to scientific river regulation in arid environments, but relevant quantitative research is lacking. Aiming to quantify the effect of ...

Abstract	Understanding how changes in channel form affect the relationships between riparian vegetation and river flow is critical to scientific river regulation in arid environments, but relevant quantitative research is lacking. Aiming to quantify the effect of channel planar complexity, one of the most dynamic aspects of channel form, on riparian vegetation-flow relationships at annual and basin scales, a comparative study was conducted on two rivers in the lower Heihe River, China. Information on riparian vegetation and channel form was derived from multi-source remote sensing imagery and the Copernicus digital elevation model, and river flow and groundwater table data were obtained from field observations. Channel planar complexity was calculated as the ratio of the total length of all channels of a river to the straight-line distance between the two ends of the river, and the riparian vegetation-flow relationship was quantified by a multiple linear model that couples riparian vegetation degradation under zero-flow condition and riparian vegetation improvement by river flow. During 2002-2020, (1) one river was 1.5 and 1.04 times the other in terms of planar complexity and profile slope, respectively; (2) the water-year runoff of one river was 3.2 × 10
Language	English
Publishing date	2023-11-30
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	121506-1
ISSN	1879-1026 ; 0048-9697
ISSN (online)	1879-1026
ISSN	0048-9697
DOI	10.1016/j.scitotenv.2023.168988
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Article ; Online: Several potentiality enhancement techniques of water flooding reservoir in placanticline

Zhang Yichi

E3S Web of Conferences, Vol 352, p

2022 Volume 01058

Abstract: The three types of oil reservoirs in water drive have entered the later stage of ultra-high water cut development [1] after three times of well pattern infilling adjustment and years of oil stabilization and water control. With the gradual transfer of ... ...

Abstract	The three types of oil reservoirs in water drive have entered the later stage of ultra-high water cut development [1] after three times of well pattern infilling adjustment and years of oil stabilization and water control. With the gradual transfer of high quality reserves to chemical flooding, the development objects of water flooding are mainly three types of oil reservoirs, and the exploitation objects are getting worse and worse, and the difficulty of controlling decline, exploiting potential and benefit development is increasing year by year. To this end, the blocks that have been tested for water control and efficiency improvement are selected to conduct precise potential-tapping tests, to carry out technological breakthroughs of “water control and efficiency improvement”, to explore and form a series of high-efficiency development technologies of water flooding, and to guide the deep potential-tapping in the ultra-high water-cut stage of water flooding [2]. This paper mainly focuses on the comprehensive utilization of injection and production well pattern, as well as the principle and effect of injection well comprehensive adjustment program and tracking adjustment program.
Keywords	water control and efficiency improvement ; precise tapping potential ; comprehensive utilization of well pattern ; adjustment plan ; Environmental sciences ; GE1-350
Language	English
Publishing date	2022-01-01T00:00:00Z
Publisher	EDP Sciences
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Evaluating two small-sample corrections for fixed-effects standard errors and inferences in multilevel models with heteroscedastic, unbalanced, clustered data.

Zhang, Yichi / Lai, Mark H C

Behavior research methods

2024

Abstract: Multilevel modeling (MLM) is commonly used in psychological research to model clustered data. However, data in applied research usually violate one of the essential assumptions of MLM-homogeneity of variance. While the fixed-effect estimates produced by ... ...

Abstract	Multilevel modeling (MLM) is commonly used in psychological research to model clustered data. However, data in applied research usually violate one of the essential assumptions of MLM-homogeneity of variance. While the fixed-effect estimates produced by the maximum likelihood method remain unbiased, the standard errors for the fixed effects are misestimated, resulting in inaccurate inferences and inflated or deflated type I error rates. To correct the bias in fixed effects standard errors and provide valid inferences, small-sample corrections such as the Kenward-Roger (KR) adjustment and the adjusted cluster-robust standard errors (CR-SEs) with the Satterthwaite approximation for t tests have been used. The current study compares KR with random slope (RS) models and the adjusted CR-SEs with ordinary least squares (OLS), random intercept (RI) and RS models to analyze small, heteroscedastic, clustered data using a Monte Carlo simulation. Results show the KR procedure with RS models has large biases and inflated type I error rates for between-cluster effects in the presence of level 2 heteroscedasticity. In contrast, the adjusted CR-SEs generally yield results with acceptable biases and maintain type I error rates close to the nominal level for all examined models. Thus, when the interest is only in within-cluster effect, any model with the adjusted CR-SEs could be used. However, when the interest is to make accurate inferences of the between-cluster effect, researchers should use the adjusted CR-SEs with RS to have higher power and guard against unmodeled heterogeneity. We reanalyzed an example in Snijders & Bosker (2012) to demonstrate the use of the adjusted CR-SEs with different models.
Language	English
Publishing date	2024-02-06
Publishing country	United States
Document type	Journal Article
ZDB-ID	231560-9
ISSN	1554-3528 ; 0743-3808 ; 1554-351X
ISSN (online)	1554-3528
ISSN	0743-3808 ; 1554-351X
DOI	10.3758/s13428-023-02325-9
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Article ; Online: A Theoretical Analysis of DeepWalk and Node2vec for Exact Recovery of Community Structures in Stochastic Blockmodels.

Zhang, Yichi / Tang, Minh

IEEE transactions on pattern analysis and machine intelligence

2024 Volume 46, Issue 2, Page(s) 1065–1078

Abstract: Random-walk-based network embedding algorithms like DeepWalk and node2vec are widely used to obtain euclidean representation of the nodes in a network prior to performing downstream inference tasks. However, despite their impressive empirical performance, ...

Abstract	Random-walk-based network embedding algorithms like DeepWalk and node2vec are widely used to obtain euclidean representation of the nodes in a network prior to performing downstream inference tasks. However, despite their impressive empirical performance, there is a lack of theoretical results explaining their large-sample behavior. In this paper, we study node2vec and DeepWalk through the perspective of matrix factorization. In particular, we analyze these algorithms in the setting of community detection for stochastic blockmodel graphs (and their degree-corrected variants). By exploiting the row-wise uniform perturbation bound for leading singular vectors, we derive high-probability error bounds between the matrix factorization-based node2vec/DeepWalk embeddings and their true counterparts, uniformly over all node embeddings. Based on strong concentration results, we further show the perfect membership recovery by node2vec/DeepWalk, followed by K-means/medians algorithms. Specifically, as the network becomes sparser, our results guarantee that with large enough window size and vertex number, applying K-means/medians on the matrix factorization-based node2vec embeddings can, with high probability, correctly recover the memberships of all vertices in a network generated from the stochastic blockmodel (or its degree-corrected variants). The theoretical justifications are mirrored in the numerical experiments and real data applications, for both the original node2vec and its matrix factorization variant.
Language	English
Publishing date	2024-01-10
Publishing country	United States
Document type	Journal Article
ISSN	1939-3539
ISSN (online)	1939-3539
DOI	10.1109/TPAMI.2023.3327631
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Article ; Online: A systematic review and meta-analysis of minimally invasive versus conventional open proctectomy for locally advanced colon cancer.

Peng, Zhang / Ya, Lu / Yichi, Zhang / Dong, Lin / Dechun, Zhang

Medicine

2024 Volume 103, Issue 11, Page(s) e37474

Abstract: Background: Locally advanced colon cancer is considered a relative contraindication for minimally invasive proctectomy (MIP), and minimally invasive versus conventional open proctectomy (COP) for locally advanced colon cancer has not been studied.: ... ...

Abstract	Background: Locally advanced colon cancer is considered a relative contraindication for minimally invasive proctectomy (MIP), and minimally invasive versus conventional open proctectomy (COP) for locally advanced colon cancer has not been studied. Methods: We have searched the Embase, Cochrane Library, PubMed, Medline, and Web of Science for articles on minimally invasive (robotic and laparoscopic) and COP. We calculated pooled standard mean difference (SMD), relative risk (RR), and 95% confidence intervals (CIs). The protocol for this review has been registered on PROSPERO (CRD42023407029). Results: There are 10132 participants including 21 articles. Compared with COP, patients who underwent MIP had less operation time (SMD 0.48; CI 0.32 to 0.65; I2 = 0%, P = .000), estimated blood loss (MD -1.23; CI -1.90 to -0.56; I2 = 95%, P < .0001), the median time to semi-liquid diet (SMD -0.43; CI -0.70 to -0.15; I2 = 0%, P = .002), time to the first flatus (SMD -0.97; CI -1.30 to -0.63; I2 = 7%, P < .0001), intraoperative blood transfusion (RR 0.33; CI 0.24 to 0.46; I2 = 0%, P < .0001) in perioperative outcomes. Compared with COP, patients who underwent MIP had fewer overall complications (RR 0.85; CI 0.73 to 0.98; I2 = 22.4%, P = .023), postoperative complications (RR 0.79; CI 0.69 to 0.90; I2 = 0%, P = .001), and urinary retention (RR 0.63; CI 0.44 to 0.90; I2 = 0%, P = .011) in perioperative outcomes. Conclusion: This study comprehensively and systematically evaluated the difference between the safety and effectiveness of minimally invasive and open treatment of locally advanced colon cancer through meta-analysis. Minimally invasive proctectomy is better than COP in postoperative and perioperative outcomes. However, there is no difference in oncological outcomes. This also provides an evidence-based reference for clinical practice. Of course, multi-center RCT research is also needed to draw more scientific and rigorous conclusions in the future.
MeSH term(s)	Humans ; Colonic Neoplasms/complications ; Postoperative Complications/epidemiology ; Postoperative Complications/etiology ; Robotics ; Proctectomy/methods ; Laparoscopy/adverse effects ; Laparoscopy/methods
Language	English
Publishing date	2024-03-15
Publishing country	United States
Document type	Meta-Analysis ; Systematic Review ; Journal Article
ZDB-ID	80184-7
ISSN	1536-5964 ; 0025-7974
ISSN (online)	1536-5964
ISSN	0025-7974
DOI	10.1097/MD.0000000000037474
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Article ; Online: Synthesis of Pyrimido[1,2-

Li, Lesong / Shi, Zhenyu / Li, Congyang / Zhang, Xiaoli / Zhang, Yichi / Ren, Weiwu

The Journal of organic chemistry

2024

Abstract: NHC-catalyzed [4+2] annulation of ... ...

Abstract	NHC-catalyzed [4+2] annulation of 2
Language	English
Publishing date	2024-04-25
Publishing country	United States
Document type	Journal Article
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/acs.joc.4c00654
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Article ; Online: Global Overview and Insights on Infodemiology and Infodemic Management.

Pang, Mingfan / Zhang, Yichi / Guo, Siyue / Yang, Xinping / Qi, Xiaopeng

China CDC weekly

2023 Volume 5, Issue 26, Page(s) 579–583

Language	English
Publishing date	2023-06-29
Publishing country	China
Document type	Journal Article
ISSN	2096-7071
ISSN (online)	2096-7071
DOI	10.46234/ccdcw2023.112
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Correcting for Sampling Error in between-Cluster Effects: An Empirical Bayes Cluster-Mean Approach with Finite Population Corrections.

Lai, Mark H C / Zhang, Yichi / Ji, Feng

Multivariate behavioral research

2024 , Page(s) 1–15

Abstract: With clustered data, such as where students are nested within schools or employees are nested within organizations, it is often of interest to estimate and compare associations among variables separately for each level. While researchers routinely ... ...

Abstract	With clustered data, such as where students are nested within schools or employees are nested within organizations, it is often of interest to estimate and compare associations among variables separately for each level. While researchers routinely estimate between-cluster effects using the sample cluster means of a predictor, previous research has shown that such practice leads to biased estimates of coefficients at the between level, and recent research has recommended the use of latent cluster means with the multilevel structural equation modeling framework. However, the latent cluster mean approach may not always be the best choice as it (a) relies on the assumption that the population cluster sizes are close to infinite, (b) requires a relatively large number of clusters, and (c) is currently only implemented in specialized software such as Mplus. In this paper, we show how using empirical Bayes estimates of the cluster means can also lead to consistent estimates of between-level coefficients, and illustrate how the empirical Bayes estimate can incorporate finite population corrections when information on population cluster sizes is available. Through a series of Monte Carlo simulation studies, we show that the empirical Bayes cluster-mean approach performs similarly to the latent cluster mean approach for estimating the between-cluster coefficients in most conditions when the infinite-population assumption holds, and applying the finite population correction provides reasonable point and interval estimates when the population is finite. The performance of EBM can be further improved with restricted maximum likelihood estimation and likelihood-based confidence intervals. We also provide an R function that implements the empirical Bayes cluster-mean approach, and illustrate it using data from the classic High School and Beyond Study.
Language	English
Publishing date	2024-02-13
Publishing country	United States
Document type	Journal Article
ISSN	1532-7906
ISSN (online)	1532-7906
DOI	10.1080/00273171.2024.2307034
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Article ; Online: Segment anything model for medical image segmentation: Current applications and future directions.

Zhang, Yichi / Shen, Zhenrong / Jiao, Rushi

Computers in biology and medicine

2024 Volume 171, Page(s) 108238

Abstract: Due to the inherent flexibility of prompting, foundation models have emerged as the predominant force in the fields of natural language processing and computer vision. The recent introduction of the Segment Anything Model (SAM) signifies a noteworthy ... ...

Abstract	Due to the inherent flexibility of prompting, foundation models have emerged as the predominant force in the fields of natural language processing and computer vision. The recent introduction of the Segment Anything Model (SAM) signifies a noteworthy expansion of the prompt-driven paradigm into the domain of image segmentation, thereby introducing a plethora of previously unexplored capabilities. However, the viability of its application to medical image segmentation remains uncertain, given the substantial distinctions between natural and medical images. In this work, we provide a comprehensive overview of recent endeavors aimed at extending the efficacy of SAM to medical image segmentation tasks, encompassing both empirical benchmarking and methodological adaptations. Additionally, we explore potential avenues for future research directions in SAM's role within medical image segmentation. While direct application of SAM to medical image segmentation does not yield satisfactory performance on multi-modal and multi-target medical datasets so far, numerous insights gleaned from these efforts serve as valuable guidance for shaping the trajectory of foundational models in the realm of medical image analysis. To support ongoing research endeavors, we maintain an active repository that contains an up-to-date paper list and a succinct summary of open-source projects at https://github.com/YichiZhang98/SAM4MIS.
MeSH term(s)	Benchmarking ; Natural Language Processing ; S-Adenosylmethionine ; Uncertainty ; Image Processing, Computer-Assisted
Chemical Substances	S-Adenosylmethionine (7LP2MPO46S)
Language	English
Publishing date	2024-02-27
Publishing country	United States
Document type	Journal Article ; Review
ZDB-ID	127557-4
ISSN	1879-0534 ; 0010-4825
ISSN (online)	1879-0534
ISSN	0010-4825
DOI	10.1016/j.compbiomed.2024.108238
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