Analysis Of Spatial Structure Research Articles

A Group-Theoretic Approach to the Bifurcation Analysis of Spatial Cosserat-Rod Frameworks with Symmetry

We present a general approach to the bifurcation analysis of spatial framework structures with symmetry. While group-theoretic methods for bifurcation problems with symmetry are well known, their actual implementation in the context of geometrically exact frameworks is not straightforward. We consider spatial structures comprising assemblages of Cosserat rods; the main difficulty arises from the nonlinear configuration space, due to the presence of (cross-sectional) rotation fields. We avoid this via a single-rod formulation, developed earlier by one of the authors, whereby the governing equations are embedded in a slightly enlarged linear space. The field equations for a framework then comprise the assembly of all such rod equations, supplemented by compatibility and equilibrium conditions at the joints. We demonstrate their equivariance under the natural symmetry group action, and the implementation of group-theoretic methods is now clear within the enlarged linear space. All potential generic, symmetry-breaking bifurcations are predicted a-priori. We then employ an open-source path-following code, which can detect and compute simple, one-dimensional bifurcations; multiple bifurcation points are beyond its capabilities. For the latter, we construct symmetry-reduced problems implemented by appropriate substructures. Multiple bifurcations are rendered simple, and the path-following code is again applicable. We first analyze a simple tripod framework, providing all details of our methodology. We then treat a more complex hexagonal space frame via the same approach. Both structures exhibit simple and double bifurcation points.

Exploration of the regional correlation and network structure characteristics of land prices: A case study of Hebei, China

It is important to explore the correlation characteristics of land markets among cities in order to promote coordinated developments. Based on the residential land prices in 168 counties in Hebei Province, this study used spatial econometric models and social network analysis to analyze the regional correlation effect and network structure evolution characteristics of residential land prices. The results indicated that: 1) the regional residential land price level has significant global spatial autocorrelation and local autocorrelation. High-High clusters were concentrated in cities around Beijing and Tianjin and provincial capitals, while Low-Low clusters were mostly distributed in central and southern Hebei. 2) The direct effect and spillover effect of influencing factors of residential land price were significantly different. The residents’ purchasing power, the socioeconomic level, and the land resources had significant impacts on the residential land price of the county itself, while the level of infrastructure and the policy environment had significant impacts on the residential land price of neighboring counties. 3) The degree centrality and betweenness centrality of residential land price in central counties of Hebei Province was generally high, showing a trend of agglomeration. However, the peripheral cities of Hebei Province lacked important central nodes in the network structure. From 2013 to 2020, increasing numbers of counties had shown the transmission function of “bridge,” and the balance of land price in the whole region had been constantly improved. The study found that the regional residential land price itself had spatial autocorrelation, and the spillover effect of its related factors was also the driving force that affects the transmission and diffusion of land price between counties. The change in the spatial network of county residential land price was primarily manifested in the transmission process starting from the central cities. The tightness of the spatial network was related to the number and distribution of central nodes. Hebei Province should focus on cultivating urban central nodes with development potential in marginal areas, create more land market growth poles according to local conditions, and accelerate the integration of land factor markets in Beijing, Tianjin, and Hebei to achieve healthy and balanced development of residential land prices. This study made up for the shortcomings of previous studies on land price correlations. The combination of correlation feature analysis and spatial network structure analysis was more helpful to reveal the characteristics of regional land price development, and the results could provide a reference for the formulation of urban land market regulation policies.

Analisis Struktur Ruang dan Perkembangan Kota di Kecamatan Wonosari Kabupaten Gunung Kidul

The development of the city is related to how the spatial structure of the city is formed, every city development becomes forming in a space in representing the use of space.. The purpose of this study was to obtain the results of spatial structure analysis and urban development in Wonosari District, Gunung Kidul Regency. This research focuses on the aspect of Wonosari District which is based on the spatial structure. The results of this study are that the physical conditions of the environment and public facilities are interrelated in the formation of the spatial structure, wherein 14 villages there is the highest number of public facilities of 28 and the lowest of 5 facilities, with a range of 5.75 so that it gets 4 classifications of the Wonosari District spatial hierarchy. A total of 2 villages become the city service center, 1 village is the city service center, 2 villages are supporting the city service center and 9 other villages are supporting the city service center. Supporting public facilities are also influenced by the physical condition of the area such as flat slopes, groundwater hydrology, and community land use.

Estimate Forest Aboveground Biomass of Mountain by ICESat-2/ATLAS Data Interacting Cokriging

Compared with the previous full-waveform data, the new generation of ICESat-2/ATLAS (Advanced Terrain Laser Altimeter System) has a larger footprint overlap density and a smaller footprint area. This study used ATLAS data to estimate forest aboveground biomass (AGB) in a high-altitude, ecologically fragile area. The paper used ATLAS data as the main information source and a typical mountainous area in Shangri-La, northwestern Yunnan Province, China, as the study area. Then, we combined biomass data from 54 ground samples to obtain the estimated AGB of 74,873 footprints using a hyperparametric optimized random forest (RF) model. The total AGB was estimated by combining the best variance function model in geostatistics with the slope that is the covariates. The results showed that among the 50 index parameters and three topographic variables extracted based on ATLAS, six variables showed a significant correlation with AGB. They were, in order, number of canopy photons, Landsat percentage canopy, canopy photon rate, slope, number of photons, and apparent surface reflectance. The optimized random forest model was used to estimate the AGB within the footprints. The model accuracy was the coefficient of determination (R2) = 0.93, the root mean square error (RMSE) = 10.13 t/hm2, and the population estimation accuracy was 83.3%. The optimized model has a good estimation effect and can be used for footprint AGB estimation. The spatial structure analysis of the variance function of footprint AGB showed that the spherical model had the largest fitting accuracy (R2 = 0.65, the residual sum of squares (RSS) = 2.65 × 10−4), the nugget (C0) was 0.21, and the spatial structure ratio was 94.0%. It showed that the AGB of footprints had strong spatial correlation and could be interpolated by kriging. Finally, the slope in the topographic variables was selected as the co-interpolation variable, and cokriging spatial interpolation was performed. Furthermore, a continuous map of AGB spatial distribution was obtained, and the total AGB was 6.07 × 107 t. The spatial distribution of AGB showed the same trend as the distribution of forest stock. The absolute accuracy of the estimation was 82.6%, using the statistical value of the forest resource planning and design survey as a reference. The ATLAS data can improve the accuracy of AGB estimation in mountain forests.

Covariables of Soil-Forming Factors and Their Influence on pH Distribution and Spatial Variability

The objectives of this study were to identify and rank the covariables of soil-forming factors that affect the distribution and spatial variability of pH in an agricultural area and to obtain a predictive map of soil pH. Samples of topsoil were obtained from different sites and taken to the laboratory, where they were prepared to determine the pH, organic matter, and percentages of particle size. In addition, the values of environmental covariables that affect pH were obtained. A database of the coordinates, laboratory results, and values of the covariables was constructed. Principal component analysis of the covariables was performed, and an analysis of the pH spatial structure was conducted and interpolated to obtain a predictive map of pH. Of the soil physical characteristics, the covariables clay and sand had a greater influence on the spatial behavior of pH with respect to the rest of the covariables of soil-forming factors, while human activity acted as a catalyst of the acidification process. Soil pH exhibited autocorrelation and moderate spatial dependence (66.7%) and was thus spatially predictable. The pH prediction map was accurate (RMSE = 0.158 and MEB = 0.020).

Strong species structure but weak geographical structure in demersal Lake Victoria cichlids.

Studying phenotypic and genetic differentiation between very young species can be very informative with regard to learning about processes of speciation. Identifying and characterizing genetic species structure and distinguishing it from spatial genetic structure within a species is a prerequisite for this and is often not given sufficient attention. Young radiations of cichlid fish are classical speciation study systems. However, it is only during the past decade that population genomics based on next-generation sequencing has begun to provide the power to resolve species and distinguish speciation from spatial population structure for the youngest of these radiations. The Lake Victoria haplochromine cichlids constitute the youngest large cichlid fish radiation, probably <20,000 years old. Earlier work showed that communities of rocky reef cichlids are composed of many reciprocally monophyletic species despite their very recent origins. Here, we build on this work by studying assemblages of offshore demersal cichlids, adding analyses of within-species spatial structure to the sympatric species structure. We sampled seven multispecies communities along a 6-km-long transect from one side of the Mwanza Gulf to the other side. We investigated whether phenotypically diagnosed putative species are reciprocally monophyletic and whether such monophyly is stable across species geographic ranges. We show that all species are genetically strongly differentiated in sympatry, that they are reciprocally monophyletic, and that monophyly is stable across distribution ranges. We found significant differentiation between geographically distinct populations in two species, but no or weak isolation by distance. We further found subtle but significant morphological differences between all species and a linear relationship between genomic and morphological distance which suggests that differences in morphology begin to accumulate after speciation has already affected genome-wide restrictions of gene flow.

Understanding the spectrum during the tearing mode locking by rotating RMP in J-TEXT

The rotating resonant magnetic perturbation (RMP) could lock the tearing mode (TM) and prevent disruption. It is found that the TM instantaneous frequency oscillates during TM locking on the RMP. In this work, the TM frequency oscillation was derived analytically based on the toroidal torque balance, which was verified experimentally. It is found that two peaks with higher frequency (2fTM0-fRMP) and lower frequency (fRMP) occurred in the spectrum when the window width of FFT was shorter than the TM frequency oscillating period. Those two peaks were explained analytically based on the description of TM instantaneous frequency. The independence of the temporal information and the spatial information of the TM was explained analytically and verified by the spatial structure analysis of each peaks. This work is important for mode structure identification and provides a scheme for mode coupling control.

충청지역의 농촌협약 특성에 관한 연구 - 농촌 공간구조 분석과 농촌생활권 설정, 농촌다움(시설)자원 활용을 중심으로 -

The purpose of this study is to present the implications of the rural living area setting and rural spatial structure analysis of the rural spatial strategy plan through case analysis. Following the decentralization of autonomy and the promotion of the transfer of state affairs to local areas, some of the general agricultural and fishing village development projects of the Ministry of Agriculture, Food and Rural Affairs were transferred to local areas. In addition, in 2020, the Ministry of Agriculture, Food and Rural Affairs introduced a rural agreement system for 113 cities and counties. However, since the understanding of the field is still low, this study attempted to present implications through a case analysis of the structure of rural space and the establishment of rural living areas in three local governments in Chungcheong. As a result of the study, in the stage of establishing the living zone, it is necessary to comprehensively review the contents reviewed in the analysis of the current status and conditions. However, the two local governments had insufficient interpretation of the axis by function and the establishment of the base area, or were using the upper plan as it was. Second, the source of the data used in the survey on the distribution status of living SOC facilities is unclear. Since the distribution status of living SOC facilities overlaps with accessibility analysis, OD data analysis, and resident survey results and is used as the basis for setting living areas, the data source should be clearly marked, and verification should be possible. Third, amenity (facility) resources were classified and analyzed according to the conditions and characteristics of local governments. The local government that applied the guidelines as they were was A local government, and the remaining local governments conducted surveys and analysis according to the current status. Forth, since the establishment of the rural living area is the minimum unit supported by government policies through future rural agreements, it is necessary to distinguish them based on quantitative standards in the process of establishing them. Only one case area presented clear grounds and standards, and the rest of the case areas presented standards but are based on non-quantitative standards. In order for rural agreements to be sustainable in the future and benefit local residents, it is necessary to use or establish a government-level institution that can collect and produce objective data. In addition, it is necessary to find ways to specify and standardize the standards for setting the living area and specify them in the guidelines.

Quantitative analysis and spatial distribution of landform spatial structure on Loess Plateau

The Loess Plateau is the largest gully geomorphic region in the world, characterized by the most intense soil erosion in a typical loess-covered area. Previous studies have focused on the terrain and texture of this region; however, there have been no systematic studies on the gully spatial structure of the Loess Plateau. Therefore, the present study investigated the characteristics and spatial distribution of landform spatial structure over the Loess Plateau. Specifically, gully weighted complex networks (GWCNs) were applied to simulate the gully spatial structure of loess landforms, and a series of quantitative indices were introduced to delineate these. Using 57 geomorphological units uniformly distributed across the Loess Plateau as test areas and six typical loess landforms as sample areas, GWCNs were constructed, and using these GWCNs, the spatial structure and internal mechanisms of typical loess landforms were explored. From a series of fresh insights, such as the regional scale-free distribution, homologous structure, tightness, community effect, connectivity, stability, and complexity, regular variations in quantitative indices delineate the spatial distribution of the characteristics of landform spatial structure over the plateau. Moreover, the spatial distribution of complex network indices exhibited strong spatial coupling with loess landforms. Overall, GWCNs could be effectively used for landform recognition and performed well. In conclusion, these experimental results suggest that introducing complex networks into landform studies can offer novel insights into landform quantitative analyses. The present work is of great significance, as it proposes a new methodology for describing the spatial structure and terrain features of landforms in quantitative analyses and furthers our understanding of landform genesis.

Metropolitan spatial structure analysis based on the identification of commuting zones with Nanjing City as an example

Commuting zone research is critical to the understanding of the operational rules of the metropolitan spatial structure and improving spatial performance. This study aims to identify the main commuting centers and zones by using cellular data with Nanjing City as the example. This study analyzes the operational features of the internal spatial structures of the city from two dimensions by merging multi-source data, namely, commuting centers and zones, thus achieving an understanding of the existing problems with the urban spatial structures and their internal causes. Results showed that the commuting zones of Nanjing are distributed in a pattern of “multiple commuting centers”, with Xinjiekou–Hunan Road and Hongwu Road–Chaotiangong–Shuangtang as the core, Mochou Lake as the main commuting area, and Dongshan and Jiangpu as the secondary commuting zones. Significant differences and similarities are discovered in our comparisons along the two dimensions of commuting zones and centers in terms of spatial structural factors, such as land use, transportation, and commuting in the city. The similarity is shown as a common declining trend in the values of all our indicators with the increase in the distance of commuting zones from the city center. However, the differences are significant in terms of the clustering features of the various parameters concerning commuting centers and zones. Specifically, four clustering patterns are discovered, namely, “monocentric clustering”, “circular monocentric clustering”, “polycentric clustering”, and “sparsely dotted distribution”. This study sheds light on the existing problems with the city's spatial structure and proposes some overall suggestions toward urban spatial structure improvement on the basis of these findings.

How is modern bedside teaching structured? A video analysis of learning content, social and spatial structures

BackgroundBedside teaching (BST) is an essential and traditional clinical teaching format. It has been subject to various impediments and has transformed over time. Besides a decrease in bedside time, there has also been a didactic diversification. In order to use time at the bedside effectively and understand the current design of BST, we here offer an evidence-based insight into how BST is practiced. This may serve as a basis for a refinement of its didactic design.MethodsIn the current study, we investigate the interrelationships between learning content and the social as well as spatial structures of BST. To this end, we have empirically analysed almost 80 hours of video material from a total of 36 BST sessions with good interrater reliability.ResultsBST lasted on average 125 min, most of which was spent in plenary and less than a third of the time at the patient’s bedside. History taking was primarily practiced at the bedside while case presentations, clinical reasoning and theoretical knowledge were largely taught away from the patient. Clinical examination took place to a similar extent in the patient’s room and in the theory room.ConclusionsEven though the filmed BSTs are not purely “bedside”, the teaching format investigated here is a typical example of undergraduate medical education. In order to maximize the teaching time available, a suitable learning space should be provided in addition to the bedside. Moreover, the clinical examination should be revised in its general sequence prior to the BST, and conscious decisions should be made regarding the social structure so as to optimize the potential of small groups and plenary sessions.

Analysis of spatial form and structure of commercial pedestrian blocks based on Isovist and big data

Commercial pedestrian blocks play an indispensable role in urban life. With the development of urban commercial intensification, the construction of commercial pedestrian blocks has ushered in a period of rapid development. To explore the spatial form and structural features of commercial pedestrian blocks, we examined the Qingniwa-Tianjin Street commercial pedestrian block in Dalian, China. We developed a new quantitative research method, using Isovist-App software simulation, big data statistics and Arc GIS analysis methods to explore the spatial morphological structure characteristics of commercial districts. The results show that Tianjin Street’s pedestrian axis has low spatial permeability and monotonous browsing routes. This suggests that the outdoor pedestrian space design does not attract crowds to wander around and stroll. The overall centrality of the space was relatively high, and the spatial accessibility was good. The walking route provided a wide field of vision, stimulating people’s desire for exploration. The space is highly guided, and people can visit according to the designed route. There is a big difference in the spatial aggregation and dispersion of POI facilities. Transportation, sports, and leisure facilities are the most evenly distributed, while shopping and life service street facilities vary considerably. During holidays, the intensity and duration of crowd activities are the largest, followed by working days and weekends. The people in the block mainly gather in the western and southern commercial complexes, and the attractiveness of outdoor pedestrian streets is lower than that of commercial complexes. Node space B has pedestrian streets with varying spatial interfaces and inconsistent visual appeal. The results can be used to support the spatial form and structural renewal design of commercial pedestrian blocks. The methods presented in this study provide a quantitative approach for the spatial analysis of other functional areas in the city.

Study of regional air pollutant dispersion scenarios and atmospheric capacity changes based on spatial structure analysis of source intensity—the case of Hohhot, China

Study of regional air pollutant dispersion scenarios and atmospheric capacity changes based on spatial structure analysis of source intensity—the case of Hohhot, China

Three-Dimensional Quantitative Coherent Diffraction Imaging of Staphylococcus aureus Treated with Peptide-Mineralized Au-Cluster Probes.

Characterizing interactions between microbial cells and their specific inhibitory drugs is essential for developing effective drugs and understanding the therapeutic mechanism. Functional metal nanoclusters can be effective inhibitory agents against microorganisms according to various characterization methods, but quantitative three-dimensional (3D) spatial structural analysis of intact cells is lacking. Herein, using coherent X-ray diffraction imaging, we performed in situ 3D visualization of unstained Staphylococcus aureus cells treated with peptide-mineralized Au-cluster probes at a resolution of ∼47 nm. Subsequent 3D mass-density mapping and quantitative structural analyses of S. aureus in different degrees of destruction showed that the bacterial cell wall was damaged and cytoplasmic constituents were released from cells, confirming the significant antibacterial effects of the Au-cluster probe. This study provides a promising nondestructive approach for quantitative imaging and paves the way for further research into microbe-inhibitor drug interactions.

Scale dependent spatial structuring of mountain river large bed elements maximizes flow resistance

Macro-roughness elements such as boulders and bedrock outcrops, collectively referred to as large bed elements (LBEs), are key features influencing hydrodynamics and morphodynamics in mountain rivers. Where LBEs are abundant and account for a substantial portion of total flow resistance, existing geomorphic theory, previous physical experiments, and limited field observations support the theory that LBE configurations adjust to maximize flow resistance. However, methods to explicitly map individual features along entire river segments are lacking, thus limiting analysis of LBE spatial structure in boulder-bedded rivers. In addressing these gaps, this study sought to develop a procedure for mapping LBEs from 3D point-clouds, explore LBE spatial structure in a real boulder-bedded river, and test the hypothesis that LBE configurations were organized to maximize flow resistance. The mapping procedure applied a ground classification algorithm to produce a roughness surface model, from which LBEs were extracted by a marker controlled watershed algorithm. Implementing the procedure, 42,176 LBEs were mapped in 13.2-km of the mountainous Yuba River (Northern California). Scale and discharge-dependent LBE concentration and spacing metrics were quantified for multiple laterally and/or hierarchically nested spatial domains and classified to differentiate three flow-resistance based hydrodynamic regimes: isolated roughness, wake interference, and skimming flow. Of these regimes, wake interference corresponds to a state of maximum resistance, so hypothesis testing involved determining if this regime was dominant. Results confirmed 25 of 28 segment- and reach-scale LBE concentrations were in the wake interference regime. However, spacing metrics classified 24 of these same spatial domains in the skimming flow regime. Concentration metrics, which quantify LBE density in a given spatial area, differ from spacing metrics, which represent LBE proximity to one another. While comparison of segment and reach-scale regime classifications by each metric concluded concentration was superior to spacing for regime classification purposes, these disparities leave open questions about this extremal model of geomorphic adjustment. Lastly, lateral variability of metrics across the river corridor had implications for discharge-dependent resistance.

Distribution and Structure Analysis of Mountain Permafrost Landscape in Orulgan Ridge (Northeast Siberia) Using Google Earth Engine

An analysis of the landscape spatial structure and diversity in the mountain ranges of Northeast Siberia is essential to assess how tundra and boreal landscapes may respond to climate change and anthropogenic impacts in the vast mountainous permafrost of the Arctic regions. In addition, a precise landscape map is required for knowledge-based territorial planning and management. In this article, we aimed to explore and enhanced methods to analyse and map the permafrost landscape in Orulgan Ridge. The Google Earth Engine cloud platform was used to generate vegetation cover maps based on multi-fusion classification of Sentinel 2 MSI and Landsat 8 OLI time series data. Phenological features based on the monthly median values of time series Normalized Difference Vegetation Index (NDVI), Green Normalized Difference Vegetation Index (GNDVI), and Normalized Difference Moisture Index (NDMI) were used to recognize geobotanical units according to the hierarchical concept of permafrost landscapes by the Support Vector Machine (SVM) classifier. In addition, geomorphological variables of megarelief (mountains and river valleys) were identified using the GIS-based terrain analysis and landform classification of the ASTER GDEM scenes mosaic. The resulting environmental variables made it possible to categorize nine classes of mountain permafrost landscapes. The result obtained was compared with previous permafrost landscape maps, which revealed a significant difference in distribution and spatial structure of intrazonal valleys and mountain tundra landscapes. Analysis of the landscape structure revealed a significant distribution of classes of mountain Larix-sparse forests and tundra. Landscape diversity was described by six longitudinal and latitudinal landscape hypsometric profiles. River valleys allow boreal–taiga landscapes to move up to high-mountainous regions. The features of the landscape structure and diversity of the ridge are noted, which, along with the specific spatial organization of vegetation and relief, can be of key importance for environmental monitoring and the study of regional variability of climatic changes.

Optimized method of lines for non-linear waveguide problems

The Method of Lines is a semi-analytical versatile tool for the solution of partial differential equations. For the analysis of spatial complex linear waveguide structures, this method is combined with impedance/admittance and field transformation, as well as with finite differences. This paper extends this approach to the treatment of structures with non-linear dielectric materials. The non-linear generalized transmission line equations are derived. An iterative algorithm based on the impedance/admittance transformation with the field transformation obtains efficient and self-consistent solutions. For demonstration, a non-linear stripe waveguide is considered. The Kerr non-linearity was investigated, though the general case is treatable. As a criterion for the correctness of the algorithm, a second harmonic generation as well as a bidirectional, spatially, and temporally energy exchange between the harmonics was examined. The specific limiting factors for the algorithm were explored. The approach can be used for any spatial structure, including, for instance, photonic crystal waveguides and metamaterials.

Analysis of China's regional differences in water consumption based on spatial structural decomposition analysis model

Analyzing the factors that affect the spatial differences in production water consumption in China is necessary to implement its most stringent water resource management system effectively. Based on the input-output tables of 31 provinces and the water-consumption data of provinces by sectors in 2017, the water consumption-economy input-output tables of 31 provinces are constructed. The spatial structural decomposition analysis method is used to analyze the impact of technology level, economic scale, and regional characteristics on spatial differences in production water consumption. The final demand effect is then decomposed into final demand sectoral structural effect, final demand distribution structure effect, population-scale effect, and consumption-level effect. The results show that production water consumption depends on the economic scale and regional characteristics. Xinjiang, Jiangsu, Guangdong, Heilongjiang, and most provinces in the central region use more production water than the average level, while those in the Beijing-Tianjin region and most in the North-west region use less than average. The decomposition results show that the technical and the final demand effects are the main factors for the spatial differences. The impact of population-scale and consumption-level contribute the most to the final demand effect.

Integral Fire Protection Analysis of Complex Spatial Steel Structure Based on Optimized Gaussian Transformation Model.

The rapid development of complex space steel structure buildings has brought new challenges to structural fire protection analysis and design. On the basis of analyzing the deficiencies of structural fire protection design in existing normative and performance-based design methods and based on the knowledge and research results of fire science, structural engineering, computer simulation, and other disciplines, this paper proposes an improved Gaussian transformation model and applied it to the overall fire performance analysis of this complex space steel structure. The proposed model is based on theoretical research and practical application of the simulation and analysis of the overall fire performance of complex spatial buildings. The coupled analysis model and system integration method of spatial overall structure fire and structure are established. The improved Gaussian transformation model is used to propose the integrity of complex spatial structures. It is a system analysis model for fire analysis. The experimental results show that the designed algorithm model can effectively realize the overall fire performance analysis of complex spatial steel structures and can provide a useful reference for China's building fire protection research, building fire protection design, fire rescue, emergency plan formulation, and other engineering practical applications.

Structural brain network measures in elderly patients with cerebral small vessel disease and depressive symptoms

ObjectivesTo investigate the relationship between diffusion tensor imaging (DTI) indicators and cerebral small vessel disease (CSVD) with depressive states, and to explore the underlying mechanisms of white matter damage in CSVD with depression.MethodA total of 115 elderly subjects were consecutively recruited from the neurology clinic, including 36 CSVD patients with depressive state (CSVD+D), 34 CSVD patients without depressive state (CSVD-D), and 45 controls. A detailed neuropsychological assessment and multimodal magnetic resonance imaging (MRI) were performed. Based on tract-based spatial statistics (TBSS) analysis and structural network analysis, differences between groups were compared, including white matter fiber indicators (fractional anisotropy and mean diffusivity) and structural brain network indicators (global efficiency, local efficiency and network strength), in order to explore the differences and correlations of DTI parameters among the three groups.ResultsThere were no significant differences in terms of CSVD burden scores and conventional imaging findings between the CSVD-D and CSVD+D groups. Group differences were found in DTI indicators (p < 0.05), after adjusting for age, gender, education level, and vascular risk factors (VRF), there were significant correlations between TBSS analysis indicators and depression, including: fractional anisotropy (FA) (r = − 0.291, p < 0.05), mean diffusivity (MD) (r = 0.297, p < 0.05), at the same time, between structural network indicators and depression also show significant correlations, including: local efficiency (ELocal) (r = − 0.278, p < 0.01) and network strength (r = − 0.403, p < 0.001).ConclusionsChanges in FA, MD values and structural network indicators in DTI parameters can predict the depressive state of CSVD to a certain extent, providing a more direct structural basis for the hypothesis of abnormal neural circuits in the pathogenesis of vascular-related depression. In addition, abnormal white matter alterations in subcortical neural circuits probably affect the microstructural function of brain connections, which may be a mechanism for the concomitant depressive symptoms in CSVD patients.