heterogeneity

摘要： The spinal cord is at risk of injury during spinal surgery.If intraoperative spinal co rd injury is identified early,irreve rsible impairment or loss of neurological function can be prevented.Different types of spinal cord injury result in damage to diffe rent spinal cord regions,which may cause diffe rent somatosensory and motor evoked potential signal res ponses.In this study,we examined electrophysiological and histopathological changes between contusion,distra ction,and dislocation spinal cord injuries in a rat model.We found that contusion led to the most severe dorsal white matter injury and caused considerable attenuation of both somatosensory and motor evoked potentials.Dislocation resulted in loss of myelinated axons in the lateral region of the injured spinal cord along the rostrocaudal axis.The amplitude of attenuation in motor evoked potential responses caused by dislocation was greater than that caused by contusion.After distraction injury,extracellular spaces were slightly but not significantly enlarged;somatosensory evoked potential res ponses slightly decreased and motor evoked potential responses were lost.Correlation analysis showed that histological and electrophysiological findings we re significantly correlated and related to injury type.Intraope rative monitoring of both somatosensory and motor evoked potentials has the potential to identify iatrogenic spinal cord injury type during surgery.

摘要： Astrocyte polarization is a new concept which is similar to microglia polarization and in which astrocytes are classified as A1(neurotoxic)and A2(neuroprotective).Several studies on astrocyte polarization have focused mainly on neurodegenerative diseases,trauma,and infections.However,the role of astrocyte polarization in glaucoma,a neurodegenerative disease,has not been fully explored.In this review,we first describe the characteristics of astrocyte astrogliosis in glaucoma,including morphological,molecular,proliferative and functional changes.We then summarize understanding of astrocyte polarization in other diseases,and show that A1 astrocytes are involved in the death of retinal ganglion cells in glaucoma,and that their neurotoxins kill only damaged retinal ganglion cells.Based on this,we propose new interesting conjecture on astrocyte polarization in glaucoma:(1)That the neurotoxin from A1 astrocytes is a product of the complement system(membrane-attacking complex),since this system is known to mediate synaptic elimination and the C3 expression is clearly increased in A1 astrocytes;(2)that reactive scar-forming astrocytes in the optic nerve head may be classified as A2 astrocytes since their ablation leads to a worse prognosis in glaucoma.Finally,current therapeutic research progress on astrocyte polarization in other diseases is also addressed.Regulation of astrocyte polarization can be achieved by extracellular microglia-related and intracellular pathways.Reduced A1 or increased A2 astrocytes can rescue the nerve.For example,glucagon-like peptide-1 receptor agonist rescues retinal ganglion cells by reducing A1 astrocytes via the extracellular microglia-related pathway in an ocular hypertension model,suggesting that regulation of astrocyte polarization as a therapeutic target in glaucoma is feasible.

摘要： Drilling results suggest that the thickness of natural gas hydrates(NGHs)in the Shenhu Area,South China Sea(SCS)are spatially heterogenous,making it difficult to accurately assess the NGHs resources in this area.In the case that free gas exists beneath hydrate deposits,the frequency of the hydrate deposits will be noticeably attenuated,with the attenuation degree mainly affected by pore development and free gas content.Therefore,the frequency can be used as an important attribute to identify hydrate reservoirs.Based on the time-frequency characteristics of deposits,this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows.Firstly,the support vector machine(SVM)method was employed to study the amplitude versus frequency(AVF)response based on seismic and well logging data.Afterward,the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform.Then,the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion.The inversion results can effectively broaden the frequency band,reflect the NGHs distribution,and reveal the NGHs reservoirs of two types,namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type.Moreover,the inversion results well coincide with the drilling results.Therefore,it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs,which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.

摘要： Based on the comparison of basic geological conditions and enrichment characteristics of shale oil plays, the heterogeneity of source and reservoir conditions and differential enrichment of medium-high maturity continental shale oil plays in China have been confirmed.(1) Compared with the homogeneous geological settings and wide distribution of marine shale oil strata in North America, the continental medium and high maturity shale oil plays in China are significantly different in geological conditions generally;continental multi-cyclic tectonic evolution forms multiple types of lake basins in multi-stages, providing sites for large-scale development of continental shale oil, and giving rise to large scale high-quality source rocks, multiple types of reservoirs, and diverse source-reservoir combinations with significant heterogeneity.(2) The differences in sedimentary water environments lead to the heterogeneity in lithology, lithofacies, and organic material types of source rocks;the differences in material source supply and sedimentary facies belt result in reservoirs of different lithologies, including argillaceous and transition rocks, and tight siltstone, and complex source-reservoir combination types.(3) The heterogeneity of the source rock controls the differentiation of hydrocarbon generation and expulsion, the diverse reservoir types make reservoir performance different and the source-reservoir configurations complex, and these two factors ultimately make the shale oil enrichment patterns different. Among them, the hydrocarbon generation and expulsion capacity of high-quality source rocks affect the degree of shale oil enrichment. Freshwater hydrocarbon source rocks with TOC larger than 2.5% and saline hydrocarbon source rocks with TOC of 2% to 10% have a high content of retained hydrocarbons and are favorable.(4) High-abundance organic shale is the basis for the enrichment of shale oil inside the source. In addition to being retained in shale, liquid hydrocarbons migrate along laminae, diagenetic fractures, and thin sandy layers, and then accumulate in laminae of argillaceous siltstone, siltstone, and argillaceous dolomite, and dolomitic siltstone suites, etc. with low organic matter abundance in the shale strata, resulting in differences in enrichment pattern.

摘要： This study applies multi-source datasets(i.e.,Baidu Heat Map data,points of interest(POIs)data,and floor area and land use data)and geographically and temporally weighted regression(GTWR)models to elaborate the spatiotemporal relationships between the built environment and urban vibrancy on both weekdays and weekends,using Guangzhou City as a case.First,we verified the spatially and temporally nonstationary nature of the built environment correlates,which have been largely ignored in previous studies based on local regression techniques.The spatially and temporally heterogeneous effects of the built environment on urban vibrancy are then presented and visualized,based on the GTWR results.We found that the elasticity of location(i.e.,distance),land use mix(i.e.,diversity),building intensity and numbers of POIs with various functions(i.e.,density)are different across time(2-h intervals within a day)and space(grids),due to people’s everyday lifestyle,time-space constraints,and geographical context(e.g.,spatial structure).The findings highlight the importance of a better understanding of the local geography on the spatiotemporal relationships for urban planners and local governments so as to put forward decision-making support for fostering and maintaining urban vibrancy.

摘要： Organoids are three-dimensional culture systems generated from embryonic stem cells,induced pluripotent stem cells,and adult stem cells.They are capable of cell proliferation,differentiation,and self-renewal.Upon stimulation by signal factors and/or growth factors,organoids self-assemble to replicate the morphological and structural characteristics of the corresponding organs.They provide an extraordinary platform for investigating organ development and mimicking pathological processes.Organoid biobanks derived from a wide range of carcinomas have been established to represent different lesions or stages of clinical tumors.Importantly,genomic and transcriptomic analyses have confirmed maintenance of intra-and interpatient heterogeneities in organoids.Therefore,this technology has the potential to revolutionize drug screening and personalized medicine.In this review,we summarized the characteristics and applications of organoids in cancer research by the establishment of organoid biobanks directly from tumor organoids or from genetically modified non-cancerous organoids.We also analyzed the current state of organoid applications in drug screening and personalized medicine.

摘要： CO_(2)+O_(2) in-situ leaching(ISL)of sandstonetype uranium ore represents the third generation of solution mining in China.In this study,reactive transport modeling of the interaction between hydrodynamic and geochemical reactions is performed to enable better prediction and regulation of the CO_(2)+O_(2) in-situ leaching process of uranium.Geochemical reactions between mining solutions and rock,and the kinetic uranium dissolution controlled by O_(2)(aq)and bicarbonate(HCO_(3)-)are considered in the CO_(2)+O_(2) ISL reactive transport model of a typical sandstone-hosted uranium ore deposit in northern China.The reactive leaching of uranium is most sensitive to the spatial distribution of the mineralogical properties of the uranium deposit.Stochastic geostatistical models are used to represent the uncertainty on the spatial distribution of mineral grades.A Monte Carlo analysis was also performed to simulate the uranium production variability over an entire set of geostatistical realizations.The ISL stochastic simulation performed with the selected geostatistical realizations approximates the uranium production variability well.The simulation results of the ISL reactive transport model show that the extent of the uranium plume is highly dependent on mineralogical heterogeneity.The uncertainty analysis suggests the effect of uranium grade heterogeneity was found to be important to improve the accurate capture of the uncertainty.This study provides guidance for the accurate simulation and dynamic regulation of the CO_(2)+O_(2) leaching process of uranium at the scale of large mining areas.

摘要： The 14th Five-Year Plan period is a critical period for China to achieve high-quality development. Based on super-efficiency slacks-based measure(SBM) model, grey-related analysis(GRA) and other models, this paper studies the heterogeneity of the coupling relationship among technological innovation, industrial transformation and environmental efficiency in the Huaihai Economic Zone during the period of 2005-2019. In addition, it analyzes the coupling mechanism of single and binary systems to the ternary system, which is of great significance for the collaborative symbiosis among systems. The findings are as follows. 1) The technological innovation, industrial transformation and environmental efficiency(TIE) systems of the Huaihai Economic Zone had significant spatial-temporal heterogeneity. Although their evaluation value fluctuated, the development trends are all positive. Ultimately, technological innovation is characterized by being high in the northeast and low in the southwest around Xuzhou, while other systems are relatively staggered in space. 2) The coupling of TIE systems is in transition, lack of orderly integration and benign interaction. However, the developing trend of interaction is also upward, and a spatial pattern driven by Xuzhou and Linyi as the dual cores has gradually formed. Moreover, the coupling is mostly manifested as outdated technological innovation and industrial transformation. Except for the final coordination of regenerative cities, the other resource types are all in transition. Cities in all traffic locations are still in transition. The overall system interaction of cities on Longhai Line(Lanzhou-Lianyungang Railway) is relatively optimal, and cities on Xinshi Line(Xinxiang-Rizhao Railway) are accelerating toward synergy. 3) The coupling status of TIE systems depends on the development of the single system and the interaction of the binary(2E) system. The coupling is closely related to technological innovation and Technology-Industry system,and is hindered by the inefficient interaction of Technology-Environment system. Specifically, the synergy of regenerative cities is attributed to the advantage of a single system and the effective integration of 2E systems. Beneficial from the advantages of environmental efficiency, the cities on Xinshi Line promote the synergy of the 2E and TIE systems. Therefore, while the Huaihai Economic Zone stimulates the development potential of the single and 2E systems, it is necessary to amplify the superimposition effect of systems in accordance on the basis of resource and location.

摘要： Air pollution,especially fine particulate matter(PM_(2.5))pollution,has a great negative impact on human production and normal life.It is a hot issue of global concern,and it is also a huge test for China’s high-quality socioeconomic development.Environmental absorption capacity(EAC)is the guarantee of the structure and function of a healthy atmospheric environmental system.It plays an important role in the automatic accommodation,absorption,and digestion of air pollutants produced by humans in the process of industrialization and civilization.Understanding the absorption capacity of environmental elements on PM_(2.5),and exploring the impact of EAC on PM_(2.5) concentration are of great significance to the development of new ideas for air pollution control.This paper constructed an index system to calculate the EAC index from two dimensions(natural resource endowment and impact of human activities),analyzed and discussed the impact of EAC on PM_(2.5) concentration and its heterogeneity effect through panel regression model,generalized panel quantile regression based on MCMC optimization and scenario analysis,by using the panel data of 30 provinces in China from 2004 to 2017.The results suggested that:(i)The overall level of national EAC was low,and the regional differences were large.EAC was influenced by natural resource endowment and human activities,while natural endowment was the main factor affecting EAC,and human activities were the main factor causing the fluctuation and the regional difference of EAC.(ii)As the result of full sample regression demonstrated,the enhancement of EAC had a significant negative influence on the reduction of PM_(2.5) concentration.In areas with high PM_(2.5) concentration,the effect of EAC was more obvious,but the effect did not necessarily increase with the increase of PM_(2.5) concentration.Also,in extreme cases,the effect did not pass the significance test.(iii)According to the results of heterogeneity effect analysis,the effect of EAC on PM_(2.5) concentration was significantly negative in sustainable scenario and emergency scenario,while the effect was not significant in Soylent Green scenario.The conclusion provides important implications for the prevention and control of air pollution and the improvement of atmospheric environmental quality.

摘要： Mechanical heterogeneity is a major characteristic of the organic-rich shale.The relation between mechanical heterogeneity and formation in-situ stress has been seldomly addressed but important to understand hydraulic fracture propagation,wellbore stability,and hydrocarbon flow.In this paper,the grid nanoindentation technique was used to characterize the heterogeneity of the mechanical properties of Longmaxi organic-rich shales from various burial depths and in-situ stress.The measured elastic modulus and hardness of each sample are deconvolved into three phases including soft phase,medium stiff phase and stiff phase according to mineral category.As the burial depth and corresponding in-situ stress increase,the overall elastic modulus and hardness of the sample enhance.Simultaneously,the percentage of soft minerals decreases,and the probability distribution tends to concentrate through 95%confidence interval evaluation which demonstrates weakened heterogeneity.Furthermore,SEM images provide evidence that extended cracking,initiated cracking,crushing and ductile deforming always occur around indentation imprints.This confirms that even under deep buried depth and high in-situ stress,brittle fracture and ductile deformation can exist synchronously.This paper demonstrates the influence of in-situ stress on the heterogeneity of shale micromechanics.