Seasonal implications for taxonomic sufficiency to simplify M-AMBI methodology in the coastal area adjacent to a eutrophic estuary

Taxonomic sufficiency(TS)refers to identifying taxa to a taxonomic level sufficient to detect community changes in stressed environments and may provide a cost-effective approach in routine monitoring programs.However,there is still limited information regarding the seasonal impact of applying TS and its implications for the ecological quality evaluation in the estuarine ecosystem.This study investigated the relationship between the multivariate-AZTI’s Marine Biotic Index(M-AMBI)and environmental variables in three seasons(i.e.,spring,summer,and autumn)in the Liaohe River Estuary.We tested the reliability of TS for simplifying the M-AMBI methodology.The results showed that family and genus level data could reproduce the spatial-temporal patterns of community structure at the species level.The M-AMBI values showed a consistent spatial distribution pattern in all sampling seasons,with a decreasing trend with the increasing distance from the estuary mouth.Both genus and family level data performed nearly as well as species level in detecting the seasonal variations of pollutants(i.e.,nutrients and total organic content).The family level M-AMBI was feasible to discern stress in the Liaohe River Estuary because of the high aggregation ratios at different taxonomic levels in all sampling seasons.These findings suggest that applying taxonomic sufficiency based on the M-AMBI provides an efficient approach for evaluating ecological quality in the Liaohe River Estuary.

Effects of shellfish culture on the community and mortality of zooplankton in a subtropical Bay

Spatial and temporal distribution of abundance,community structure and succession,and mortality of zooplankton were examined in a subtropical bay—the Qinzhou Bay,Guangxi,South China,to evaluate the impact of oyster culture on zooplankton.Data on zooplankton abundance,phytoplankton biomass,and environmental parameters were collected in 12 routine samplings at four sites in the Qinzhou Bay in 2018.Results show that the hydrological environment in the estuary affected the temporal variation of zooplankton of the Qinzhou Bay.However,the oyster culture affected the spatial distributions of zooplankton.The abundance of zooplankton outside the oyster farm was higher than that inside,whereas the mortality outside the oyster farm,on the contrary,was lower than that inside.Oyster culture in the Qinzhou Bay had built a significant impact on the abundance and community composition of zooplankton,and the food shortage caused by the ingestion of oyster might exacerbate the mortality of zooplankton in the Qinzhou Bay.In addition,the large-scale oyster culture increased the spatial heterogeneity of the community structure of zooplankton inside and outside the oyster farms.Findings of this study provide a reference for future policy-making in aquaculture management.

Research on Network Cognition Model and Mechanism of Intelligent Information Network

Intellectualization has been an inevitable trend in the information network,allowing the network to achieve the capabilities of self-learning,self-optimization,and self-evolution in the dynamic environment.Due to the strong adaptability to the environment,the cognitive theory methods from psychology gradually become an excellent approach to construct the intelligent information network(IIN),making the traditional definition of the intelligent information network no longer appropriate.Moreover,the thinking capability of existing IINs is always limited.This paper redefines the intelligent information network and illustrates the required properties of the architecture,core theory,and critical technologies by analyzing the existing intelligent information network.Besides,we innovatively propose a novel network cognition model with the network knowledge to implement the intelligent information network.The proposed model can perceive the overall environment data of the network and extract the knowledge from the data.As the model’s core,the knowledge guides the model to generate the optimal decisions adapting to the environmental changes.At last,we present the critical technologies needed to accomplish the proposed network cognition model.

Relationship between thermal anomalies in Tibetan Plateau and summer dust storm frequency over Tarim Basin,China

The dust storm is the most important and frequent meteorological disaster over Tarim Basin, which causes huge damages on local social economics. How to predict the springtime and summertime dust storm oc- currence has become a hot issue for meteorologists. This paper employed the data of dust storm frequency and 10-m wind velocity at 35 stations over Tarim Basin and the reanalysis data from the National Center for Environ- mental Prediction and the National Center for Atmospheric Research （NCEP/NCAR） during 1961-2007 to study the relationship between dust storm frequency （DSF） in summer over Tarim Basin and the thermal anomalies in Tibetan Plateau in May by using the statistical methods, such as Empirical Orthogonal Function （EOF）, correlation and binomial moving average. The results show when negative anomalies in Tibetan Plateau and positive anomalies in its southern region are present along 30~N （the second mode of surface temperature anomalies by EOF decomposition） in May, the time coefficient （PC2） plays an important role in summer DSF variation and has a close relation with the summer DSF at both inter-annual and decadal time scales. When negative anomalies in Tibetan Plateau and positive anomalies are present in its southern region （PC2 in positive phase）, there is an anomalous anticyclone in North China, which weakens the northwest wind and is not beneficial for cold air moving from high latitude to the Tarim Basin, and the circulation pattern is hard to result in dust storm weather. Furthermore, the sea level pressure （SLP） increased over Tarim Basin and the direction of SLP gradient reversed, which resulted in the 10-m wind velocity slowing down, so the DSF decreased. From above all, it can be conclude that the thermal anomalies in Tibetan Plateau in May has important effects on the summertime dust storm frequency over Tarim Basin and the PC2 can be used as a prediction factor for the summertime dust storm occurrence.

A Survey on Heliumspeech Communications in Saturation Diving

With the development of society and the progress of technology,more and more ocean activities are carried out.It results in booming of deep-sea diving.The use of helium-oxygen mixture(as a kind of breathing gas)solves the physiological problems of divers in saturated diving,but it brings about the Heliumspeech voice communication problem,the drop of speech intelligibility.There is no doubt that the effective speech communication must be provided for supporting the life and work of divers in deep-sea.This paper describes the mechanism of forming heliumspeech,discusses the effects of pressure and helium environment on the speech spectrum,compares the pros and cons of the time-domain and frequency-domain unscrambling techniques,shows the challenges in heliumspeech communications.Finally,it briefly introduces the deep learning,and points out that deep learning/machine learning may be a perfectly unscrambling technique.

Development of a CLDN18.2-targeting immuno-PET probe for non-invasive imaging in gastrointestinal tumors

Claudin18.2(CLDN18.2)is a tight junction protein that is overexpressed in a variety of solid tumors such as gastrointestinal cancer and oesophageal cancer.It has been identified as a promising target and a potential biomarker to diagnose tumor,evaluate efficacy,and determine patient prognosis.TST001 is a recombinant humanized CLDN18.2 antibody that selectively binds to the extracellular loop of human Claudin18.2.In this study,we constructed a solid target radionuclide zirconium-^(89)(^(89)Zr)labled-TST001 to detect the expression of in the human stomach cancer BGC823CLDN18.2 cell lines.The[^(89)Zr]Zr-desferrioxamine(DFO)-TST001 showed high radiochemical purity(RCP,>99%)and specific activity(24.15±1.34 GBq/mmol),and was stable in 5%human serum albumin,and phosphate buffer saline(>85%RCP at 96 h).The EC_(50) values of TST001 and DFO-TST001 were as high as 0.413±0.055 and 0.361±0.058 nM(P>0.05),respectively.The radiotracer had a significantly higher average standard uptake values in CLDN18.2-positive tumors than in CLDN18.2-negative tumors(1.11±0.02 vs.0.49±0.03,P=0.0016)2 days post injection(p.i.).BGC823CLDN18.2 mice models showed high tumor/muscle ratios 96 h p.i.with[^(89)Zr]Zr-DFO-TST001 was much higher than those of the other imaging groups.Immunohistochemistry results showed that BGC823CLDN18.2 tumors were highly positive(+++)for CLDN18.2,while those in the BGC823 group did not express CLDN18.2().The results of ex vivo biodistribution studies showed that there was a higher distribution in the BGC823CLDN18.2 tumor bearing mice(2.05±0.16%ID/g)than BGC823 mice(0.69±0.02%ID/g)and blocking group(0.72±0.02%ID/g).A dosimetry estimation study showed that the effective dose of[^(89)Zr]Zr-DFO-TST001 was 0.0705 mSv/MBq,which is within the range of acceptable doses for nuclear medicine research.Taken together,these results suggest that Good Manufacturing Practices produced by this immuno-positron emission tomography probe can detect CLDN18.2-overexpressing tumors.

Benthic bacterial communities indicate anthropogenic activity footprints in coastal area under long-term marine spatial planning practice

Marine spatial planning(MSP)is designed to divide the sea area into different types of functional zones,to implement corresponding development activities.However,the long-term impacts of anthropogenic activities associated with MSP practice on the marine microbial biosphere are still unclear.Yalu River Estuary,a coastal region in northeast of China,has been divided into fishery&agricultural(F&A)zone,shipping&port(S&P)zone and marine protected area(MPA)zone by a local MSP guideline that has been run for decades.To examine the effects of long-term executed MSP,benthic bacterial communities from different MSP zones were obtained and compared in this study.The results revealed significant differences in the bacterial community structure and predict functions among different zones.Bacterial genera enriched in different zones were identified,including SBR1031 in MPA,Woeseia and Sva0996 in S&P,and Halioglobus in F&A.In addition,correlations between some bacterial genera and sediment pollutants were uncovered.Furthermore,bacteria related to sulphide production were more abundant in the F&A zone,which was according to the accumulation of sulphides in this area.Moreover,bacteria associated with chemoheterotrophy and fermentation were more predominant in the S&P zone,consistent with high levels of organic matter and petroleum caused by shipping.Our findings indicated benthic bacterial communities could bring to light the anthropogenic activity footprints by different activities induced by long-term MSP practice.

Customer Churn Prediction Framework of Inclusive Finance Based on Blockchain Smart Contract

In view of the fact that the prediction effect of influential financial customer churn in the Internet of Things environment is difficult to achieve the expectation,at the smart contract level of the blockchain,a customer churn prediction framework based on situational awareness and integrating customer attributes,the impact of project hotspots on customer interests,and customer satisfaction with the project has been built.This framework introduces the background factors in the financial customer environment,and further discusses the relationship between customers,the background of customers and the characteristics of pre-lost customers.The improved Singular Value Decomposition(SVD)algorithm and the time decay function are used to optimize the search and analysis of the characteristics of pre-lost customers,and the key index combination is screened to obtain the data of potential lost customers.The framework will change with time according to the customer’s interest,adding the time factor to the customer churn prediction,and improving the dimensionality reduction and prediction generalization ability in feature selection.Logistic regression,naive Bayes and decision tree are used to establish a prediction model in the experiment,and it is compared with the financial customer churn prediction framework under situational awareness.The prediction results of the framework are evaluated from four aspects:accuracy,accuracy,recall rate and F-measure.The experimental results show that the context-aware customer churn prediction framework can be effectively applied to predict customer churn trends,so as to obtain potential customer data with high churn probability,and then these data can be transmitted to the company’s customer service department in time,so as to improve customer churn rate and customer loyalty through accurate service.

A more consistent intraluminal rhesus monkey model of ischemic stroke

Endovascular surgery is advantageous in experimentally induced ischemic stroke because it causes fewer cranial traumatic lesions than invasive surgery and can closely mimic the pathophysiology in stroke patients. However, the outcomes are highly variable, which limits the accuracy of evaluations of ischemic stroke studies. In this study, eight healthy adult rhesus monkeys were randomized into two groups with four monkeys in each group： middle cerebral artery occlusion at origin segment （M1） and middle cerebral artery occlusion at M2 segment. The blood flow in the middle cerebral artery was blocked completely for 2 hours using the endovascular microcoil placement technique （1 mm × 10 cm） （undetachable）, to establish a model of cerebral ischemia. The microcoil was withdrawn and the middle cerebral artery blood flow was restored. A reversible middle cerebral artery occlusion model was identified by hematoxylin-eosin staining, digital subtraction angiography, magnetic resonance angiography, magnetic resonance imaging, and neurological evaluation. The results showed that the middle cerebral artery occlusion model was successfully established in eight adult healthy rhesus monkeys, and ischemic lesions were apparent in the brain tissue of rhesus monkeys at 24 hours after occlusion. The rhesus monkeys had symptoms of neurological deficits. Compared with the M1 occlusion group, the M2 occlusion group had lower infarction volume and higher neurological scores. These experimental findings indicate that reversible middle cerebral artery occlusion can be produced with the endovascular microcoil technique in rhesus monkeys. The M2 occluded model had less infarction and less neurological impairment, which offers the potential for application in the field of brain injury research.

Immunodiagnostic efficacy of detection of Schistosoma japonicum human infections in China:a meta analysis

Objective:To assess the diagnostic efficacy of the currently most widely used indirect hemagglutination assay(IHA) and enzyme-linked immunosorbent assay(ELISA) for detection of Schistosoma japonicum human infections.Methods:A comprehensive search was undertaken from China National Knowledge Infrastructure,Wanfang Database.VIP Database,PubMed. Cochrane Library,Science Citation Index Expanded.Proquest,and the inclusion and exclusion criteria were strictly settled.The funnel plot was used to assess the publication bias.Cochran’s Q test was employed to measure the homogeneity between studies,a summary receiver operating characteristic(SROC) curve was used to compare the diagnostic accuracy between the IHA and ELISA qualitatively by means of the Weighted Least Square method,the Ordinary Least Square method and the Robust regression method,and the diagnostic odds ratio(DOR) was drawn to compare the accuracy quantitatively.Results:Out of 785 publications,19 papers were eventually selected for analysis.Literature finality assessment indicated that minor publication bias existed in studies pertaining IHA test,but no bias was found in literatures regarding ELISA test.The heterogeneity test showed a heterogeneity between studies was present(χ~2 =466.07 and 34.67. both P values【0.0001).The areas under the SROC curves of IHA were all higher than that of ELISA test using the three methods(Weighted Least Square method:0.766 vs.0.695.Ordinary Least Square method:0.826 vs.0.741.Robust regression:0.815 vs.0.715).The TPR* values for IHA and EUSA were 0.710.0.759.0.749.and 0.650.0.686 and 0.666.respectively,and OR values were 5.997.9.937.8.893.and 3.432.4.784 and 3.959.respectively.The DOR of IHA was 9.41(95% CI:4.88-18.18).and 4.78(95%CI:3.21-7.13) for ELISA.Conclusions:All above results revealed that the diagnostic performance of IHA is better than that of ELISA.However,taking into account their unsatisfactory diagnostic value in areas with low infection intensity,a search for a better diagnostic test that can be applied in field situations in China should be given high priority.

Differentiation of rhesus adipose stem cells into dopaminergic neurons

LIM homeobox transcription factor la （Lmxla） has the capacity to initiate the development program of neuronal cells and promote the differentiation of embryonic stem cells into dopaminergic neurons. In this study, rhesus adipose stem cells were infected with recombinant adenovirus carrying the Lmxla gene and co-cultured with embryonic rat neural stem cells. Cell differentiation was induced using sonic hedgehog and fibroblast growth factor-8. Immunofluorescence staining showed that cells were positive for neuron-specific enolase and ^-tubulin II1. Reverse transcription-PCR results demonstrated that rhesus adipose stem cells were not only positive for neuron-specific enolase and I^-tubulin III, but also positive for the dopaminergic neuron marker, tyrosine hydroxylase, neurofilament, glial cell line-derived neurotrophic factor family receptor a2 and nuclear receptor related factor 1. The number of Lmxla gene-infected cells expressing the dopaminergic neuron marker was substantially greater than the number of cells not infected with Lmxla gene. These results suggest that Lmxla-mediated regulation combined with the strategy of co-culture with neural stem cells can robustly promote the differentiation of rhesus adipose stem cells into dopaminergic neurons.

Trends and abrupt changes in surface vapor content over Tarim Basin during the last 50 years

The surface vapor content has a close correlation with the generation of precipitation. Based on the atmospheric circulation data and surface vapor content data from 37 weather stations across the Tarim Basin dur- ing 1961-2010, the paper analyzed the vapor variation trend, period, abrupt changes and their causes. The results show that the increase trend of surface vapor content over the Tarim Basin mostly conforms with the average trend coefficient of 0.48. There were 3 centers displaying a trend of high vapor increase and 3 centers displaying a low vapor increase. These centers were distributed in strips and blocks across the basin from northeast to southwest. Notable inter-decadal variations in annual and seasonal vapor contents occurred in the Tarim Basin during the 50 years of the study period, with more vapor after the mid-1980s and less vapor in the 1960s and the 1970s. The significant increase in vapor content in the 50 year period occurred mostly in the 1980s and the 1990s. The in- creasing trend across the four seasons was strongest in summer, reaching 0.43, and weakest in spring. Great variations existed between the spring trend and the annual, summer, autumn and winter trends. During the 50-year study period, there are distinguishable periods of 4-6 years and 8-10 years in which the annual and seasonal vapor contents varied alternately between low and high concentrations. The annual vapor content and that of the four individual seasons all changed abruptly in about the mid-1980s （a〈0.05）. The west wind circulation, Tibetan Plateau circulation and the annual mean temperatures of the Tarim Basin are the main factors that influenced the surface vapor content over the study area, of which the Tibetan Plateau circulation may be the most important one.

The atmospheric circulation patterns influencing the frequency of spring sand-dust storms in the Tarim Basin

Using NCEP/NCAR reanalysis data and the sand-storm frequency data fi＇om 37 weather stations in the Tarim Basin for the period 1961-2009, the relationship between the frequency of spring sandstorms in the Tafim Basin and the associated atmospheric circu- lation pattems is analyzed in this study. We found significantly negative correlations between sandstorm frequency and the 500-hPa geopotential height over the Paris Basin and midwestem Mongolia, while there were positive correlations over the Ural River region. The rising of the 500-hPa geopotential height in midwestem Mongolia and its falling over the Ural region corre- spond to a weakening of the large-scale wave patterns in the Eurasian region, which directly causes the frequency of the sand-dust storms in the Tarim Basin to decline. Also, the abrupt decline in the spring sandstorm frequency in the Tarim Basin observed in the last half-century is associated with profound changes in the atmospheric circulation in these key regions. At the interannual scale, the strengthened cyclonic atmospheric circulation patterns in the western part of Mongolia and the anticyclonic patterns over the East European plains at 500-hPa geopotential height, are responsible for frequent sandstorm occurrences in the Tarim Basin.

Neurturin gene cloning and expression in Vero cells

BACKGROUND： Transplantation of cell lines expressing neurturin （NTN） has been used to treat animal models of Parkinson＇s disease. However, gone homology between humans and rats varies greatly, so experimental results are not entirely suitable for understanding cellular transplantation in humans. OBJECTIVE： To explore expression of NTN in African green monkey kidney cells （Vero cells）; to obtain a stably NTN expressing cell line. DESIGN, TIME AND SETTING： An observation study of gone engineering and cellular biology was performed at the Institute of Medical Biology, Chinese Academy of Medical Science and Peking Union Medical College between 2005 and 2008. MATERIALS： Human embryonic hepatic tissues, expression vector pcDNA3, and Vero cells were prepared in this laboratory. Primers were synthesized by TaKaRa Biotechnology, Dalian, China; RNA extraction kit and plasmid extraction kit were purchased from Shanghai Watson Bioengineering, China; G418 and MTT were purchased through Sigma, USA; Lipofectamine2000 was a product of Invitrogen, USA; mice anti-human NTN antibody and fluorescent labeling goat anti-mouse IgG antibody were provided by Jingmei Biotech, China. METHODS： Total RNA was harvested from human embryonic hepatic tissues, and NTN cDNA was cloned by RT-PCR method, followed by subcloning into the pcDNA3 eukaryotic expression vector. The obtained pcDNA3/hNTN was stably transfected into Vero cells using Lipofectamine 2000, and stably expressing clones were selected using G418. MAIN OUTCOME MEASURES： NTN mRNA and protein expressions were respectively identified by RT-PCR and immunofluorescence. The morphology of transfected cells was observed under inverted microscopy, and the growth characteristics of those cells were determined using MTT method. RESULTS： A clonal cell line, stably expressing human NTN mRNA and protein, was obtained through stable transfection of pcDNA3/hNTN into Vero cells. The transfected Veto cells exhibited irregular morphology, rather than a spindle shape. The growth retardation phase was prolonged, but the number of cells was identical to non-transfected cells. CONCLUSION： Vero cell lines, which stably expressed human NTN protein, were obtained, and expression patterns of these cell lines were acceptable.

A Comparison between TGT and Cz Grown Nd:YAG

Large sized neodymium-doped Y3Al5O12 （Nd：YAG） laser crystals have been grown by temperature gradient technique （TGT） method and compared with Czochralski （Cz） method. The comparison of these two crystal growth methods has been listed. The results showed that the TGT method has many advantages over the Cz method. The concentration distribution of Nd ions in the crystals was determined and the absorption spectra of these crystals have been investigated and compared. The TGT grown highly doped Nd：YAG crystal has a larger absorption FWHM than that of Cz grown Nd：YAG crysral. Highly doped Nd：YAG （～2.8 at. pct） crystals could be obtained by TGT.

大理州健康人群乙型肝炎表面抗体水平分析

目的了解2016~2018年大理州人群乙型肝炎(乙肝)表面抗体水平(HBsAb),为乙肝防控提供科学依据。方法采集11454份居民血清样本(12个行政区),通过酶联免疫吸附试验(ELISA)法分析HBsA水平情况。结果(1)6231份血清样本检验为阳性(男性2767人,女性3464人),阳性率为31.31%~92.50%,其中:城市达到54.07%,农村达到54.41%(2)HBsAb水平在8至17月齡人群中最高(92.50%),在25至34周岁人群中最低(31.31%)。(3)HBsAb水平与年龄呈负相关(rs=-0.397,P<0.001),与免疫史呈正相关,差异均有统计学意义(P<0.001)。结论本地区居民HBsAb水平较低,应积极推广成人乙肝疫苗接种,以防控乙型肝炎病毒的传播。

Development of TD-BEM Formulation for Dynamic Analysis for Twin-Parallel Circular Tunnels in an Elastic Semi-Innite Medium

In order to simulate the propagation process of subway vibration of parallel tunnels in semi-infinite rocks or soils,time domain boundary element method(TD-BEM)formulation for analyzing the dynamic response of twin-parallel circular tunnels in an elastic semi-infinite medium is developed in this paper.The time domain boundary integral equations of displacement and stress for the elastodynamic problem are presented based on Betti’s reciprocal work theorem,ignoring contributions from initial conditions and body forces.In the process of establishing time domain boundary integral equations,some virtual boundaries are constructed between finite boundaries and the free boundary to form a boundary to refer to the time domain boundary integral equations for a single circular tunnel under dynamic loads.The numerical treatment and solving process of time domain boundary integral equations are given in detail,including temporal discretization,spatial discretization and the assembly of the influencing coefficients.In the process of the numerical implementation,infinite boundary elements are incorporated in time domain boundary element method formulation to satisfy stress free conditions on the ground surface,in addition,to reduce the discretization of the boundary of the ground surface.The applicability and efficiency of the presented time domain boundary element formulation are verified by a deliberately designed example.

Diagnosis of primary clear cell carcinoma of the liver based on Faster region-based convolutional neural network

Background:Distinguishing between primary clear cell carcinoma of the liver(PCCCL)and common hepatocellular carcinoma(CHCC)through traditional inspection methods before the operation is difficult.This study aimed to establish a Faster region-based convolutional neural network(RCNN)model for the accurate differential diagnosis of PCCCL and CHCC.Methods:In this study,we collected the data of 62 patients with PCCCL and 1079 patients with CHCC in Beijing YouAn Hospital from June 2012 to May 2020.A total of 109 patients with CHCC and 42 patients with PCCCL were randomly divided into the training validation set and the test set in a ratio of 4:1.The Faster RCNN was used for deep learning of patients’data in the training validation set,and established a convolutional neural network model to distinguish PCCCL and CHCC.The accuracy,average precision,and the recall of the model for diagnosing PCCCL and CHCC were used to evaluate the detection performance of the Faster RCNN algorithm.Results:A total of 4392 images of 121 patients(1032 images of 33 patients with PCCCL and 3360 images of 88 patients with CHCC)were uesd in test set for deep learning and establishing the model,and 1072 images of 30 patients(320 images of nine patients with PCCCL and 752 images of 21 patients with CHCC)were used to test the model.The accuracy of the model for accurately diagnosing PCCCL and CHCC was 0.962(95%confidence interval[CI]:0.931-0.992).The average precision of the model for diagnosing PCCCL was 0.908(95%CI:0.823-0.993)and that for diagnosing CHCC was 0.907(95%CI:0.823-0.993).The recall of the model for diagnosing PCCCL was 0.951(95%CI:0.916-0.985)and that for diagnosing CHCC was 0.960(95%CI:0.854-0.962).The time to make a diagnosis using the model took an average of 4 s for each patient.Conclusion:The Faster RCNN model can accurately distinguish PCCCL and CHCC.This model could be important for clinicians to make appropriate treatment plans for patients with PCCCL or CHCC.

Probing bundle-wise abnormalities in patients infected with human immunodeficiency virus using fixel-based analysis:new insights into neurocognitive impairments

Background:Changes in white matter(WM)underlie the neurocognitive damages induced by a human immunodeficiency virus(HIV)infection.This study aimed to examine using a bundle-associated fixel-based analysis(FBA)pipeline for investigating the microstructural and macrostructural alterations in the WM of the brain of HIV patients.Methods:This study collected 93 HIV infected patients and 45 age/education/handedness matched healthy controls(HCs)at the Beijing Youan Hospital between January 1,2016 and December 30,2016.All HIV patients underwent neurocognitive evaluation and laboratory testing followed by magnetic resonance imaging(MRI)scanning.In order to detect the bundle-wise WM abnormalities accurately,a specific WM bundle template with 56 tracts of interest was firstly generated by an automated fiber clustering method using a subset of subjects.Fixel-based analysis was used to investigate bundle-wise differences between HIV patients and HCs in three perspectives:fiber density(FD),fiber cross-section(FC),and fiber density and cross-section(FDC).The between-group differences were detected by a two-sample t-test with the false discovery rate(FDR)correction(P<0.05).Furthermore,the covarying relationship in FD,FC and FDC between any pair of bundles was also accessed by the constructed covariance networks,which was subsequently compared between HIV and HCs via permutation t-tests.The correlations between abnormal WM metrics and the cognitive functions of HIV patients were explored via partial correlation analysis after controlling age and gender.Results:Among FD,FC and FDC,FD was the only metric that showed significant bundle-wise alterations in HIV patients compared to HCs.Increased FD values were observed in the bilateral fronto pontine tract,corona radiata frontal,left arcuate fasciculus,left corona radiata parietal,left superior longitudinal fasciculus III,and right superficial frontal parietal(SFP)(all FDR P<0.05).In bundle-wise covariance network,HIV patients displayed decreased FD and increased FC covarying patterns in comparison to HC(P<0.05),especially between associated pathways.Finally,the FCs of several tracts exhibited a significant correlation with language and attention-related functions.Conclusions:Our study demonstrated the utility of FBA on detecting the WM alterations related to HIV infection.The bundle-wise FBA method provides a new perspective for investigating HIV-induced microstructural and macrostructural WM-related changes,which may help to understand cognitive dysfunction in HIV patients thoroughly.