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Background To evaluate the diagnostic performance of T2 mapping in differentiating WHO grade II glioma from high-grade glioma (HGG). Methods We conducted a single-center, retrospective diagnostic study. Confirmed diffuse glioma (WHO grade II-IV) patients who underwent post-contrast T1-weighted imaging, T2-weighted imaging, and T2 mapping were included. All diagnoses were based on histological and molecular tests. Seventy-five percent of cases were subsampled to generate receiver operating characteristic (ROC) curves and areas under the curve (AUC), while the remaining cases were used to test the accuracy of T2 mapping. Subsampling was repeated four times. Age, T2 relaxation time, and contrast-enhancement status were used to generate a multivariable ROC curve. T2 relaxation time was also used to generate ROC curves to predict the isocitrate dehydrogenase (IDH) status. Results A total of 159 patients were included in the study. After four repeats of subsampling, the AUCs of the T2 mapping ROC curve were 0.801 (95% CI: 0.724-0.879), 0.795 (95% CI: 0.714-0.875), 0.803 (95% CI: 0.723-0.884), and 0.801 (95% CI: 0.716-0.886), with an average sensitivity of 0.753 and an average specificity of 0.767. When applied to the remaining 25% of cases, the accuracy was 75%, 93.75%, 82.50%, and 71.74%. The AUC of the multivariable ROC was 0.927 (95% CI: 0.882-0.971). IDH-mutant and IDH-wildtype gliomas have significantly different T2 relaxation times (146.28 and 124.10 ms, respectively; P=0.001), and the AUC of IDH-mutant prediction was 0.687 (95% CI: 0.585-0.789). Conclusions Quantitative T2 mapping differentiated WHO grade II glioma from HGG with moderate sensitivity and specificity. Given the advantages of short acquisition times and the absence of a contrast agent, our study suggests the application of T2 mapping in pre-operative glioma grading is feasible.

Objective The aim of this study was to find out the relationship between serum biomarkers and cerebral collateral status in acute ischemic stroke with cerebral large artery atherosclerosis. Methods We enrolled patients with ischemic stroke due to large artery atherosclerosis within 7 days of symptom onset, age 18-80 years, from August 2016 to December 2017. Twelve biomarkers representing different pathophysiological mechanisms were tested after admission. Whole-brain perfusion combined with multiphase computed tomography angiography was performed to assess cerebral collateral structure and function. Results Fifty-two patients completed the test of candidate biomarkers and recruited in this study. The mean age was 55.0 (11.1) years, 42 (80.8%) patients were male, 20 (38.5%) had poor collateral, 36 (69.2%) patients had anterior circulation stenosis or occlusion. Compared with poor collateral group, the level of MMP-9 (135,475.00 pg/ml vs. 103,612.00 pg/ml, p = 0.040) and PGF (5.75 pg/ml vs. 3.46 pg/ml, p = 0.046) was significantly higher in good collateral group. The adjusted OR (95%CI) of MMP-9 and PGF were 5.533 (1.10-27.74, p = 0.038), 7.73 (1.41-42.39, p = 0.018), respectively. sTie-2 level had a positive correlation with proportion of Tmax 4-6 (r = 0.302, p = 0.033) and HMW-KGN had negative correlation with proportion of Tmax 6-8 (r = -0.338, p = 0.02). After adjustment, the correlation of sTie-2 level and proportion of Tmax 4-6 was statistically significant (p = 0.003), and correlation of HMW-KGN and Tmax6-8 was not statistically significant (p = 0.056). Discussion Serum PGF and MMP-9 levels may correlate with collateral status based on MP-CTA in acute ischemic stroke patients with cerebral large artery atherosclerosis. Higher PGF and MMP-9 concentration associated with good collateral status.

Background and Purpose: Intraluminal thrombus (ILT) is an emerging imaging marker in acute ischemic stroke. We aimed to investigate the association of ILT with outcomes of acute large vessel occlusion (LVO) patients receiving endovascular treatment. Methods: Acute LVO stroke patients who underwent endovascular treatment within 24 hours, in a prospective, nationwide registry were enrolled. Pretreatment digital subtraction angiography was reviewed for the presence of ILT. The primary outcome was 90-day functional dependence (modified Rankin Scale scores, 3–6). Secondary outcomes included 24-hour LVO, 90-day death, and symptomatic intracranial hemorrhage. Results: Among 711 patients enrolled, 75 (10.5%) with ILT were less likely to have 90-day functional dependence compared with those without ILT (adjusted odds ratio, 0.53 [95% CI, 0.31–0.90]; P =0.021). The same trend was found among those with successful reperfusion (modified Thrombolysis in Cerebral Infarction 2b–3; P =0.008) but not in those without successful reperfusion ( P =0.107). Presence of ILT was also independently associated with a lower rate of 24-hour LVO (adjusted odds ratio 0.34 [95% CI, 0.13–0.89]; P =0.028). However, those with or without ILT had similar risks of symptomatic intracranial hemorrhage and 90-day death. Conclusions: Among acute LVO patients receiving endovascular treatment, pretreatment ILT-positive patients may have a better 90-day functional outcome (versus ILT-negative) but similar risk of death and symptomatic intracranial hemorrhage. The possibly favorable effect of ILT patients remained in those with successful reperfusion. Registration: URL: http://www.chictr.org.cn ; Unique identifier: ChiCTR1900022154.

Background and Purpose: We aimed to evaluate the impact of cortical microinfarcts (CMIs) on functional outcome after endovascular treatment in patients with acute ischemic stroke. Methods: In a multicenter registration study for RESCUE-RE (a registration study for Critical Care of Acute Ischemic Stroke After Recanalization), eligible patients with large vessel occlusion stroke receiving endovascular treatment, who had undergone 3T magnetic resonance imaging on admission or within 24 hours after endovascular treatment were analyzed. We evaluated the presence and numbers of CMIs with assessment of axial T1, T2-weighted images, and fluid-attenuated inversion recovery images. The primary outcome was functional dependence or death defined as modified Rankin Scale scores of 3 to 6 at 90 days. Secondary outcomes included early neurological improvement, any intracranial hemorrhage, symptomatic intracranial hemorrhage, and mortality. We investigated the independent associations of CMIs with the outcomes using multivariable logistic regression in overall patients and in subgroups. Results: Among 414 patients (enrolled from July 2018 to May 2019) included in the analyses, 96 (23.2%) patients had at least one CMI (maximum 6). Patients with CMI(s) were more likely to be functionally dependent or dead at 90 days, compared with those without (55.2% versus 37.4%; P P =0.04) and multiple CMIs (CMIs ≥2; adjusted odds ratio, 7.41 [95% CI, 2.48−22.17]; P Conclusions: Acute large vessel occlusion stroke patients receiving endovascular treatment with CMI(s) were more likely to have a poor functional outcome at 90 days, independent of patients’ characteristics. Such associations may be dose-dependent. Registration: URL: http://www.chictr.org.cn ; Unique identifier: ChiCTR1900022154.

Background and Purpose We investigated the relationship between basilar artery (BA) atherosclerotic stenosis features and vertebral artery (VA) stenosis and explored whether BA stenosis features are associated with perforator stroke after stenting. Methods Patients with BA stenosis who underwent HRMRI and DSA were recruited. Patients were divided into proximal BA stenosis and middle-or-distal BA stenosis groups, and then subgroup analyses were performed based on whether they had VA stenosis. BA plaque features were evaluated by HRMRI. Artery stenosis was measured by DSA. The incidence of perforator stroke after BA stenting was recorded, and the potential association between BA stenosis features and perforator stroke was analyzed. Results One hundred and seventy-four patients were consecutively enrolled. Patients with proximal BA stenosis had a higher proportion of severe stenosis than those with middle-or-distal BA stenosis ( P = 0.027). In the subgroup analysis, this difference mainly existed in patients complicated with VA stenosis ( P = 0.023). Patients with proximal BA stenosis had a higher proportion of strong plaque enhancement than those with middle-or-distal BA stenosis ( P Conclusion Patients with proximal BA stenosis had a higher proportion of severe stenosis and strong plaque enhancement, particularly in patients complicated with VA stenosis and VBJ stenosis. Perforator stroke after BA stenting may be related to distribution, burden and characteristics of BA lesions.

We aimed to investigate the correlation between an overall cerebral small vessel disease (CSVD) burden and outcomes after endovascular treatment (EVT) for patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO).In a multicenter registry study, we enrolled patients with EVT for anterior-circulation LVO-stroke. In 3.0-T MR imaging, we assessed 4 CSVD imaging markers, lacunes, white matter hyperintensities, cerebral microbleeds, and enlarged perivascular spaces, each assigned a score of 0 or 1 and summed up to an overall CSVD burden score of 0-4. We dichotomized the overall CSVD severity as none to mild (score 0-2) and moderate to severe (3-4). Primary outcome was 90-day functional dependence or death (modified Rankin Scale (mRS) 3-6). Secondary outcomes included increase in NIH Stroke Scale ≥ 4 within 24 h (early neurological deterioration (END)) and within 7 days, symptomatic intracranial hemorrhage, 90-day mRS 2-6, and 90-day mortality.Among 311 patients (63.0% male; mean age 65.1 ± 12.7 years), 260 (83.6%) had none-to-mild and 51 (16.4%) had moderate-to-severe overall CSVD burden. Moderate-to-severe CSVD burden was not significantly associated with the primary outcome (47.1% versus 45.4%; p0.05 in univariate and multivariate logistic regression), or the secondary outcomes except for a higher risk of END (11.8% versus 3.1%; p0.05 in multivariate analyses). Sensitivity analyses with 0-1 versus 2-4 of the CSVD burden score, and the score as an ordinal variable, showed similar results.An overall moderate-to-severe CSVD burden was not associated with 90-day functional dependence or death, after EVT for anterior-circulation LVO.ChiCTR1900022154 KEY POINTS: • Moderate-to-severe cerebral small vessel disease burden on MRI should not be an exclusion indicator in determining the eligibility of an acute ischemic stroke patient for endovascular treatment.

Background and purposeIt remains controversial if endovascular treatment (EVT) can improve the outcome of patients with acute basilar artery occlusion (BAO). This study aims to compare the functional outcomes between EVT with and without intravenous thrombolysis (IVT) first in patients who had acute ischaemic stroke (AIS) due to BAO.MethodsPatients who had AIS with BAO who underwent EVT within 24 hours of onset were enrolled in this multicentre cohort study, and the efficacy and safety were compared between IVT+EVT and direct EVT. The primary outcome was 90-day functional independence. All outcomes were assessed with adjusted OR (aOR) from the multivariable logistic regression. In addition, a meta-analysis was performed on all recently published pivotal studies on functional independence after EVT in patients with BAO.ResultsOf 310 enrolled patients with BAO, 241 (78%) were treated with direct EVT and 69 (22%) with IVT+EVT. Direct EVT was associated with a worse functional outcome (aOR, 0.46 (95% CI 0.24 to 0.85), p=0.01). IVT+EVT was associated with a lower percentage of patients who needed ≥3 passes of stent retriever (10.14% vs 20.75%). The meta-analysis regression revealed a potential positive correlation between bridging with IVT first and functional independence (r=0.14 (95% CI 0.05 to 0.24), pConclusionsThis study showed that compared with direct EVT, EVT with IVT first was associated with better functional outcomes in patients with BAO treated within 24 hours of onset. The meta-analysis demonstrated similar favourable efficacy of IVT first followed by EVT in patients with BAO.

Background To investigate whether collateral status could modify the associations between post‐thrombectomy blood pressure (BP) measures and outcomes. Methods and Results Patients with anterior‐circulation large‐vessel‐occlusion successfully recanalized in a multicenter endovascular thrombectomy registry were enrolled. Pretreatment collateral status was graded and dichotomized (good/poor) in angiography. Maximum, minimum, and mean systolic BP (SBP) and BP variability (assessed by the SD, coefficient of variation) during the initial 24 hours after endovascular thrombectomy were obtained. The primary outcome was unfavorable 90‐day outcome (modified Rankin Scale score 3–6). Secondary outcomes included symptomatic intracranial hemorrhage and 90‐day mortality. Adjusted odds ratios (aOR) of BP parameters over the outcomes were obtained in all patients and in patients with good/poor collaterals. Among 596 patients (mean age 66 years; 59.9% males), 302 (50.7%) patients had unfavorable 90‐day outcome. In multivariable analyses, higher mean SBP (aOR, 1.59 per 10 mm Hg increment; 95% CI, 1.26–2.02; P 140 mm Hg (versus ≤120 mm Hg; aOR, 4.27; 95% CI, 1.66–10.97; P =0.002), and higher SBP SD (aOR, 1.08 per 1‐SD increment; 95% CI, 1.01–1.16; P =0.02) were respectively associated with unfavorable 90‐day outcome in patients with poor collateral but not in those with good collateral. A marginal interaction between SBP coefficient of variation tertiles and collaterals on 90‐day functional outcome ( P for interaction, 0.09) was observed. A significant interaction between SBP coefficient of variation tertiles and collaterals on 90‐day mortality ( P for interaction, 0.03) was observed. Conclusions Higher postprocedural BP is associated with 90‐day unfavorable outcomes after successful endovascular thrombectomy in patients with poor collateral. Registration URL: https://www.chictr.org.cn ; Unique identifier: ChiCTR1900022154.

There has been explosive growth of wind farm installations in recent years due to the fact that wind energy is gaining worldwide popularity. However, the maintenance of these offshore or onshore wind turbines, especially in remote areas, remains a challenging task. In this work, vision-based autonomous wind turbine inspection using a quadrotor is designed based on realistic assumptions. Both simulation and Hardware-In-the-Loop (HIL) testing results have shown the effectiveness of the proposed approach.

Background and purposeIn-stent restenosis (ISR) is one of the long-term adverse outcomes of endovascular angioplasty and stenting for symptomatic intracranial arterial stenosis. In this study, we try to evaluate the safety and efficacy of endovascular treatment for intracranial ISR.MethodsWe retrospectively collected patients with intracranial ISR who underwent endovascular treatment from June 2012 to August 2019 at a high-volume stroke center. Successful recanalization was defined as ≤30% residual stenosis. Stroke, myocardial infarction, and death after stenting within 30 days were used to evaluate periprocedural safety. Recurrent stroke in the territory of the culprit vessel and re-ISR in patients with clinical and vascular imaging follow-up data were used to evaluate the long-term outcome.Results32 patients (59.6±7.2 years old) with ISR were recruited, including 22 patients (68.8%) treated with balloon dilatation, 8 patients (25%) with stenting, and 2 patients (6.3%) with failed procedures. Successful recanalization was achieved in 71.9% (23/32) of patients. There was no stroke, myocardial infarction or death within 30 days after the procedure. Recurrent stroke was found in 10.7% (3/28) of the patients, and re-ISR was found in 42.1% (8/19) of the patients. The re-ISR rate was lower in patients with stenting than in those with balloon dilatation (0% vs 57.1%, p=0.090), and in patients with successful recanalization than in those with unsuccessful recanalization (33.3% vs 75.0%, p=0.352), but with no statistically significant difference.ConclusionsThe periprocedural safety of endovascular treatment for intracranial ISR may be acceptable, but the long-term rates of recurrent stroke and re-ISR remain at high levels.

Unmanned Aerial Vehicles (UAVs) have been successfully employed in cooperative tasks over recent years, particularly in the applications for smart cities. In such scenario, a networked control system (NCS) framework is usually adopted since measurement and actuation data are mainly transmitted through communication networks. This paper proposes an integrated control architecture for a Cloud-based fixed-wing UAV system, where the control logic resides in the Cloud and sensing and actuating signals are transmitted over a realistic wireless network. The proposed control strategy leverages model predictive control (MPC) and a specialized Kalman filter in combination with two ad-hoc buffers, which enables simultaneous compensation for measurement and control input packet dropouts. Simulations of a nonlinear aircraft model show the effectiveness and advantages of proposed integrated scheme over an existing linear quadratic (LQ)-based control strategy.

Model-based control (MBC) techniques have been successfully developed for flight control applications of unmanned aerial vehicles (UAVs) in recent years. However, their heavy reliance on the fidelity of the plant model coupled with high computational complexity make the design and implementation process challenging. To overcome such challenges, attention has been focused on the use of artificial neural networks (ANNs) to study complex systems since they show promise in system identification and controller design, to say the least. This survey aims to provide a literature review on combining MBC techniques with ANNs for UAV flight control, with the goal of laying the foundation for efficient controller designs with performance guarantees. A brief discussion on frequently-used ANNs is presented along with an analysis of their time complexity. Classification/comparison of existing dynamic modeling approaches and control techniques is provided. Challenging research questions and an envisaged control architecture are also posed for future development.

Background Collateral flow is associated with clinical outcomes for patients with Moyamoya disease and served as a parameter for patient selection of therapeutic strategies. Therefore, we explored whether a noninvasive imaging modality, computed tomography perfusion (CTP) source images (CTP-Sis), could be used to identify the presence and intensity of collateral flow using digital subtraction angiography (DSA) as a gold standard for collateral flow. Methods CTP-Sis and DSA were performed for 24 patients with unilateral Moyamoya disease. A collateral grading system was developed based on arterial and venous phase CTP-Sis, imitating the DSA score system. Two neuroradiologists scored the DSA images using a collateral grading scale for the regions of interest corresponding to the Alberta Stroke Program Early computed tomography Score (ASPECTS) methodology. Another two neuroradiologists scored CTP-Sis in a similar manner. Agreement between the CTP-Sis and DSA consensus scores was determined, including kappa statistics. Results The agreement between the CTP-Sis and DSA consensus readings was moderate to strong, with a weighted kappa value of 0.768 [95% confidence interval (CI), 0.703-0.832], but there was a better agreement for readers of CTP-Sis, as compared with those of DSA. The sensitivity and specificity for identifying collaterals with CTP-Sis were 0.714 (95% CI, 0.578-0.851) and 0.995 (95% CI, 0.985-1.000), respectively. Conclusions CTP-Sis could help identify in a noninvasive manner the presence and intensity of collateral flow in patients with unilateral Moyamoya disease using DSA as a gold standard. Further study with a large number of cases is warranted. Further application of this method to other cerebrovascular diseases including acute ischemic stroke can also be warranted.

Laser peen texturing (LPT), which is a new surface texturing technology, was proposed to fabricate micro-dimple arrays on copper surface. Pin-on-disk experiments were conducted under different normal loads and sliding speeds to investigate friction and wear behaviors of untextured and textured samples in starved lubrication. It was found that friction performance of the surface is improved significantly after LPT. Microscope observation and EDS analysis showed that textured surface could reduce both abrasive and adhesive wear as compared to untextured surface. Results also indicated that an optimum texture density might exist at which surface shows the best friction and wear behavior.

Subsurface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. It is meaningful to rapid evaluate the depth of subsurface cracking through the measurement of surface roughness under different grinding parameters. Based on the features of surface and subsurface cracks as well as the kinetic analysis of surface grinding, the relationship between surface roughness and subsurface crack depth was established. Surface grinding experiments for optical glass BK7 were conducted. Utilizing optical microscope, optical profiling system and polishing-etching technique, the dependence of surface roughness and subsurface crack depth on grinding parameters was systematically analyzed. The predicted model of the relationship between surface roughness and subsurface crack depth was compared with experimental results. It was found that the relationship between surface roughness and subsurface crack depth is influenced by the half apex angle of abrasive grain as well as the magnitude of extra grain extrusion.

Grinding is one of the most important processes to manufacture hard-brittle materials such as optical glass. It is often desired to increase the material removal rate while maintaining the desired surface quality. The success of this approach relies on the better understanding of the relationship between the grinding modes and the characteristics of surface and subsurface integrities. Based on the kinematic analysis of horizontal surface grinding as well as the features of grinding-induced cracks, four grinding modes were proposed. They are brittle mode, semi-brittle mode, semi-ductile mode and ductile mode. The horizontal surface grinding of optical glass BK7 has been studied using diamond grinding wheel. The four different grinding modes have been investigated with the characteristics of surface morphologies before and after etching, surface roughness, subsurface damages as well as indentation depth. It was found that the level of surface roughness and depth of subsurface damage were strongly dependent on grinding mode. This study provides valuable insights into the material removal mechanism and the dependence of surface and subsurface integrities on grinding mode.

Edge detection is often regarded as a basic step in range image processing by virtue of its crucial effect. The majority of existing edge detection methods cannot satisfy the requirement of efficiency in many industrial applications due to huge computational costs. In this paper, a novel instantaneous method, named RIDED-2D is proposed for denoising and edge detection for 2D scan line in range images. In the method, silhouettes of 2D scan line are classified into eight types by defining a few new coefficients. Several discriminant criteria on large noise filtering and edge detection are stipulated based on qualitative feature analysis on each type. Selecting some feature point candidates, a practical parameter learning method is provided to determine the threshold set, along with the implementation of an integrated algorithm by merging calculation steps. Because all the coefficients are established based on distances among the points or their ratio, RIDED-2D is inherently invariant to translation and rotation transformations. Furthermore, a forbidden region approach is proposed to eliminate interference of the mixed pixels. Key performances of RIDED-2D are evaluated in detail by including computational complexity, time expenditure, accuracy and stability. The results indicate that RIDED-2D can detect edge points accurately from several real range images, in which large noises and systematic noises are involved, and the total processing time is less than 0.1 millisecond on an ordinary PC platform using the integrated algorithm. Comparing with other state-of-the-art edge detection methods qualitatively, RIDED-2D exhibits a prominent advantage on computational efficiency. Thus, the proposed method qualifies for real-time processing in stringent industrial applications. Besides, another contribution of this paper is to introduce CPU clock counting technique to evaluate the performance of the proposed algorithm, and suggest a convenient and objective way to estimate the algorithm's time expenditure in other platforms.

To get insight into the deformation and fracture behavior of brittle materials during abrasive process, scratch tests with linearly increasing normal load and constant normal load were conducted on BK7 using Vickers indenters. The effect of the applied normal load on the characteristics of surface cracks as well as the square of the scratch depth was found insensitive to the two load conditions discussed here. By taking both scratch and residual depths into consideration, a model of scratch hardness for brittle material was developed. Based on this scratch hardness, the correlation between the depth of the subsurface cracks and the scratch depth was established and was found in general agreement with the experimental results.

In order to obtain the fundamental information on the deformation and fracture behavior of brittle materials during precision and ultra-precision grinding, micron and sub-micron scale scratch tests were conducted on optical glass BK7 using Vickers indenters. Three types of surface cracking were observed around the scratch grooves. They are lateral cracking, radial cracking and cracking in front of the moving indenter. It is found that lateral cracking is the main damage type due to its large damage size and low crack initiation load. The effect of surface cracking on the relationship between the normal load and the square of scratch depth was studied. The plastic zone size as well as the sliding blister field strength was expressed as a function of the contact zone size of the indenter. A prediction model for the size of damage zone induced by lateral cracking was established and was compared with experimental results.

In order to get insight into the characteristics of chipping behaviors and material removal mechanism during grinding, both single and double scratch tests for optical glass BK7 were performed on a nanoindenter. Utilizing optical microscope, optical profiling system and displacement transducers, the scratch morphology, material removal volume and scratch depth were analyzed with applied normal load and scratch separation distance. In ductile mode of single scratching, obvious plastic ridges were formed on both sides of the groove and the volume of material removed is negligible. Under loading conditions discussed here, no obvious chipping occurs around the single scratch even when lateral and radial cracks were generated. During double scratching, three types of cracking interaction were observed and resulted in different chipping features. In brittle scratch mode, the material removal volume during double scratching is strongly dependent on separation distance. There exists a critical separation distance where the material removal volume reached its maximum. The difference in depths of the two sequential scratches was also found to be sensitive to both normal load and separation distance.

Crofton weed (Ageratina adenophora) is a highly invasive weed that has spread into several provinces of southern China. This study compares carabid assemblages originating from native pastures with assemblages in Crofton weed dominated communities in the Lancang County, Yunnan Province, to assess how the invasion of this neophyte impacts the community structure of ground-dwelling arthropods. Over a period of 16 months, a total of 1574 carabid beetles representing 28 species were collected at two types of pasture, and 679 carabid beetles representing 34 species at stands of Crofton weed. The most common carabid species, Tetragonoderus arcuatus and Harpalus indicus, were mostly found in the pastures, while four of the five rarest species were present exclusively under Crofton weed. Alpha-diversity and evenness of carabid assemblages were greater under Crofton weed. Three distinct groups of carabid species were separated according to indicator values and a characterization of habitats: habitat generalists, Crofton weed specialists and native pasture specialists. The distribution of carabid species was related to environmental parameters such as depth of litter layer, total phosphorus, height of vegetation, amount of fresh biomass and pH of the soil. According to this study, the invasion of Crofton weed will alter the structure of carabid communities, but will not necessarily reduce the alpha-diversity of carabid assemblages.

Diversity and species composition of carabid beetles were investigated at Quzhou county in the North China Plain. The study area was originally affected by high salinity and desalinized in three stages in 1973, 1978 and 1982. At sites desalinized in 1982, carabids were sampled at field margins as well as inside fields to investigate the role of field margins as refuge habitats. Furthermore, samples were taken from field margins desalinized in 1973 and 1978, respectively, to explore long-term developments of carabid assemblages following desalinization. At margins, soil salinity, N contents and the number of plant species as well as the height of dominant plants were recorded and their correlation with the species composition of carabids explored. Overall carabid diversity at Quzhou was low compared to areas not affected by high salinity. Field margins yielded significantly higher numbers of both species and individuals, whereas assemblages within the field had a low diversity and a homogeneous species composition. Carabid diversity slightly increased in relation to decreased soil salt contents and time elapsed since desalinization. These results may be explained by field margins serving as refuge to many carabid species and by an overall low species pool of carabids in Quzhou due to former high salinity, current high levels of fertilizer and pesticide applications, and by a comparatively low colonization rate of carabids to the area. As different carabid species varied strongly in their reaction to environmental parameters, the preservation of a diverse set of habitats will best protect the current diversity of these beetles in the agricultural landscape of Quzhou.