Central Collapse Research Articles

Pilon fracture with central articular surface collapse treated by posterior tibial fenestration indirect reduction and compression technique: Two cases report.

Central collapsed fracture blocks traditionally require either an anteromedial or anterolateral approach for reduction. However, existing techniques face challenges such as soft tissue damage and compromised tibial strength, especially in pilon fractures with central articular surface collapse and an intact anterior cortex, as classified under 43B2.3 in the 2018 Orthopaedic Trauma Association/Association for the Study of Internal Fixation Fracture and Dislocation Classification Compendium. We address the management of pilon fractures with central articular surface collapse, focusing on 2 cases where conventional reduction techniques posed a risk to soft tissues and tibial integrity. The patients presented with pilon fractures characterized by a central articular surface collapse and an intact anterior cortex, aligning with the 43B2.3 classification. A novel approach was employed, utilizing posterior tibial fenestration and indirect reduction with compression techniques. This method leveraged the talus as a template for precise articular surface realignment. Both cases demonstrated excellent reduction of the distal tibial articular surface and achieved favorable functional recovery of the ankle, evidenced by high American Orthopedic Foot and Ankle Society Ankle Hindfoot Scale scores during the 3-year follow-up. The posterior tibial fenestration technique offers significant advantages for distal tibial pilon fracture reduction. It allows for precise articular realignment, facilitates bone grafting, and minimizes soft tissue and cortical bone disruption. This method is particularly effective for pilon fractures with an intact anterolateral cortex and central articular collapse, providing a valuable surgical alternative.

Identification of Ground Fissure Development in a Semi-Desert Aeolian Sand Area Induced from Coal Mining: Utilizing UAV Images and Deep Learning Techniques

The occurrence of surface strata movement in underground coal mining leads to the generation of numerous ground fissures, which not only damage the ecological environment but also disrupt building facilities, lead to airflow and easily trigger coal spontaneous combustion, induce geological disasters, posing a serious threat to people’s lives, property, and mining production. Therefore, it is particularly important to quickly and accurately obtain the information of ground fissures and then study their distribution patterns and the law of spatial-temporal evolution. The traditional field investigation methods for identifying fissures have low efficiency. The rapid development of UAVs has brought an opportunity to address this issue. However, it also poses new questions, such as how to interpret numerous fissures and the distribution law of fissures with underground mining. Taking a mine in the Shenfu coalfield on the semi-desert aeolian sand surface as the research area, this paper studies the fissure recognition from UAV images by deep learning, fissure development law, as well as the mutual feed of surface condition corresponding to the under-ground mining progress. The results show that the DRs-UNet deep learning method can identify more than 85% of the fissures; however, due to the influence of seasonal vegetation changes and different fissure development stages, the continuity and integrity of fissure recognition methods need to be improved. Four fissure distribution patterns were found. In open-cut areas, arc-shaped fissures are frequently observed, displaying significant dimensions in terms of depth, length, and width. Within subsidence basins, central collapse areas exhibit fissures that form perpendicular to the direction of the working face. Along roadways, parallel or oblique fissures tend to develop at specific angles. In regions characterized by weak roof strata and depressed basins, abnormal reverse-“C”-shaped fissures emerge along the mining direction. The research results comprehensively demonstrate the process of automatically identifying ground fissures from UAV images as well as the spatial distribution patterns of fissures, which can provide technical support for the prediction of ground fissures, monitoring of geological hazards in mining areas, control of land environmental damage, and land ecological restoration. In the future, it is suggested that this method be applied to different mining areas and geotechnical contexts to enhance its applicability and effectiveness.

Spatio-Temporal Patterns and Driving Factors of Green Development Level of Urban Agglomerations in the Yellow River Basin

ABSTRACT Promoting green development (GD) is key for the Yellow River Basin (YRB) to step into the phase of high-quality development. This study constructs a green development level (GDL) evaluation system based on the PSR (Pressure-State-Response) model, and estimates the GDL of urban agglomerations (UAs) in the YRB from 2008 to 2019 using the entropy weight-TOPSIS model. Then the Moran’I and the Theil index are adopted to explore the spatio-temporal patterns of the GDL, and the Geo-detector is used to investigate the driving factors of the GDL. The results suggest that: (1) The GDL of UAs in the YRB is characterized by “low growth” and “unbalanced,” with a general pattern of “east-west prominence but central collapse”. (2) The GDL in the YRB shows significant spatial correlation characteristic. (3) The main sources of regional variation of the GDL in the UAs is inter-group differences in 2008–2013 and intra-group differences in 2014–2019. (4) The main driver of the differences of the GDL is economic development, and the effect of the interaction of any two driving factors is greater than that of the single factor.

Assessing the network characteristics and structural effects of eco-efficiency: A case study in the urban agglomerations in the middle reaches of Yangtze River, China

Crude economic development models create severe environmental pressures. Eco-efficiency (EE) is an important basis for evaluating ecological civilization in China. Under the national strategy of ecological priority and green development in China's Yangtze River Economic Belt, the urban agglomerations in the middle reaches of Yangtze River (UAMRYR) was considered as a case study and an evaluation index system of county EE was constructed based on multi-source remote sensing data, the EE values from 2009 to 2018 were measured by a super slack-based measure (Super-SBM) model, the spatial correlations of EE were revealed by an improved gravity model, the spatial network characteristics of EE were portrayed by social network analysis, and the nature of network effects were further explored by multiple linear regression models. Findings of the study included EE has been shown to be indeed spatially correlated.The EE of the nodes, the differences increased, the transmission pattern was relatively stable, and the association was characterized by bidirectional inequity. The spatial network of EE was characterized by small groups, whose tightness was small and increasingly loose overall, and the overall network operation efficiency is low. In terms of the spatial structure of individual network, the Degree Centrality (DC) showed the circle structure, the Closeness Centrality (CC) demonstrated ‘central collapse’, and the Betweenness Centrality (BC) evolved into five ‘core-periphery’ sub-groups from the ‘circle distribution’. Regarding the structural effects, in terms of EE improvement, the UAMRYR nodes were mainly through the agglomeration effect as well as dissemination channels and spillover paths, the core nodes were self-sufficient, and the edge nodes mainly relied on, the radiation role of core nodes, the transmission role of intermediary nodes, and their own active integration and connection roles. This study provides a new perspective for understanding EE and these findings are important for promoting the synergistic improvement of green development in China and other countries.

MHD instability dynamics and turbulence enhancement towards the plasma disruption at the HL-2A tokamak

The evolutions of MHD instability behaviors and enhancement of both electrostatic and electromagnetic turbulence towards the plasma disruption have been clearly observed in the HL-2A plasmas. Two types of plasma disruptive discharges have been investigated for similar equilibrium parameters: one with a distinct stage of a small central temperature collapse (sim 5–10%) around 1 millisecond before the thermal quench (TQ), while the other without. For both types, the TQ phase is preceded by a rotating 2/1 tearing mode, and it is the development of the cold bubble from the inner region of the 2/1 island O-point along with its inward convection that causes the massive energy loss. In addition, the micro-scale turbulence, including magnetic fluctuations and density fluctuations, increases before the small collapse, and more significantly towards the TQ. Also, temperature fluctuations measured by electron cyclotron emission imaging enhances dramatically at the reconnection site and expand into the island when approaching the small collapse and TQ, and the expansion is more significant close to the TQ. The observed turbulence enhancement near the X-point cannot be fully interpreted by the linear stability analysis by GENE. Evidences suggest that nonlinear effects, such as the reduction of local E_rtimes B shear and turbulence spreading, may play an important role in governing turbulence enhancement and expansion. These results imply that the turbulence and its interaction with the island facilitate the stochasticity of the magnetic flux and formation of the cold bubble, and hence, the plasma disruption.

Treatment of acute type A aortic dissection with the Ascyrus Medical Dissection Stent in a consecutive series of 57 cases.

The Ascyrus Medical Dissection Stent (AMDS) has been recently introduced as an alternative for total arch replacement in acute aortic dissection type A (AADA). The aim of this study was to evaluate the postoperative outcomes after AMDS treatment in a large contemporary cohort of AADA patients. Data acquisition was performed retrospectively at 2 German aortic centres between 2020 and 2022 and comprised the perioperative parameters and postoperative results of all AADA patients. All patients treated with the AMDS for AADA were included in the study. The primary end point was in-hospital mortality. Secondary end points were defined as early postoperative and AMDS-related complications. Fifty-seven AADA patients treated by AMDS were included in the study group. The mean age was 64.6 ± 10.8 years and 59.7% (n = 34) were males. The actual in-hospital mortality was considerably lower than the predicted mortality risk by the German registry for acute aortic dissection type A score (16% vs 22%). The median ICU and in-hospital stay were 5 (interquartile range: 3-13) and 12 (interquartile range: 10-22) days, respectively. Postoperative complications comprised acute renal insufficiency (37%) with need for temporary (16%) or permanent dialysis (5%), delirium (26%), re-exploration for bleeding (14%), tracheostomy (14%) and new stroke (4%). A new AMDS-related complication (central stent collapse) was observed in 9% (n = 5) by postoperative computed tomography and chest X-ray. The incidence of complete central AMDS collapse did not impact 30-day mortality. The AMDS may be successfully used in AADA with acceptable 30-day mortality in accordance with the German registry for acute aortic dissection type A score. However, careful preoperative evaluation of the patient's individual aortic anatomy regarding potential contraindications and proper device implantation are strongly recommended to avoid complete central AMDS collapse.

Spatial Differentiation and Influencing Factors in the Ecological Well-Being Performance of Urban Agglomerations in the Middle Reaches of the Yangtze River: A Hierarchical Perspective.

Improving the ecological well-being performance (EWP) of natural resources and environmental consumption in relation to human well-being, within the ecological boundary, is necessary for sustainable development. This study used the Super-SBM model to measure the urban EWP of urban agglomeration in the middle reaches of the Yangtze River (MRYRUA) in 2020. The spatial differentiation characteristics of EWP in the MRYRUA were identified. The heterogeneity in the direction and size of the influencing factors of EWP at different urban hierarchy (UH) levels was empirically tested by establishing a threshold model. The results are as follows: (1) In 2020, the EWP of the study area showed a trend of high levels in the southwest and low levels in the northeast. The EWP presented a multi-center “core–periphery” distribution, and the characteristic of “central collapse” was evident. The UH level of the middle and lower hierarchy-level cities was inconsistent with its EWP. (2) A non-single linear relationship was found between the influencing factors of the EWP of the MRYRUA and the EWP. The impacts of technological progress, industrial structure, environmental regulation, and population density on the EWP of the MRYRUA all showed threshold characteristics. (3) Heterogeneity and stages were both observed for the influencing factors of EWP under different UH levels. The effect of technological progress on EWP presented the characteristics of bidirectional and two-stage developments, and environmental regulation presented the features of a significant positive three-stage development. Both industrial structure and population density presented two-stage aspects, but the former acted in a negative direction, while the latter served in a positive order. This study provides a theoretical basis for the government to formulate differentiated regional policies and promote the coordinated improvement of EWP among cities at all hierarchy levels in the urban agglomeration. This study is of great significance to the sustainable development of urban agglomerations. Its results can provide a reference for other urban agglomerations, metropolitan areas, and city clusters worldwide to coordinate economic development, ecological protection, and to improve people’s well-being.

Environmental regulation, R&D investment, and green technology innovation in China: Based on the PVAR model.

The unreasonable economic development model of human beings has caused the environmental pollution problem to become increasingly serious. In order to achieve a positive relationship and interaction between environmental regulation, research and development (R&D) investment, and green technology innovation, and effectively solve the “strange circle” problem between high-quality economic development and environmental pollution in China and even the world, this paper takes the panel data of industrial enterprises above designated size in Chinese mainland 31 provinces from 2009 to 2019 as a research sample. The comprehensive index of R&D investment and green technology innovation was established by the entropy method, and the panel vector autoregressive (PVAR) model was constructed from the dynamic endogenous perspective, and the dynamic interaction and regional heterogeneity between environmental regulation, R&D investment, and green technology innovation were empirically analyzed by using impulse response function and variance decomposition. We obtain the following findings: (1) Environmental regulation has a two-way interaction relationship with R&D investment and green technology innovation, and R&D investment has a promotion effect on the “green degree” of technological innovation, but its role is still weak and has lagging characteristics. (2) There is significant regional heterogeneity in the dynamic responses of the eastern, central and western parts of China. (3) In the long run, environmental regulation has a “negative crowding out effect” on R&D investment in the central region, and the phenomenon of “central collapse” still exists but will gradually weaken. Environmental regulation has a “positive innovation compensation effect” on green technology innovation. Green technology innovation and R&D investment have an obvious “Pareto improvement” effect on environmental regulation, especially in the eastern region. The conclusions of this study help to clarify the dynamic interaction between environmental regulation, R&D investment, and green technology innovation, further improve environmental regulatory policies and green technology innovation R&D decision-making, and provide an effective way to achieve green and sustainable development in China and other parts of the world.

Core radiative collapse characterisation and integrated modelling in WEST plasmas

In the full tungsten environment of WEST, during its first phase of operation, around 25% of the pulses exhibited a rapid central electron temperature collapse. In its first phase, WEST plasmas were mostly heated by lower hybrid current drive (LHCD) and ion cyclotron resonance heating (ICRH). In this publication, the collapsing pulses are analysed to understand the key actuators at play. Experimentally, an initial slow reduction of central electron temperature due to a density increase is observed, while the central tungsten profile is flat and constant in time. Then, radiative collapse occurs: the core tungsten profile peaks rapidly, at the same time, the central hard x-ray channel measurement decreases indicating a change in core LHCD absorption. Integrated modelling is used to explore the causality chain. To capture the collapse speed, both, tungsten core peaking and reduction of central LHCD absorption are required. When central LHCD power absorption is reduced, core electron and ion temperature profiles flatten which reduces the tungsten neoclassical thermal screening and leads to the observed core tungsten accumulation.

Measurement and Spatial-Temporal Evolution Characteristics of Low-Carbon Cities with High-Quality Development: The Case Study of the Yangtze River Economic Belt, China

Carrying out measurements of low-carbon city development levels and exploring their core driving factors are focuses of attention in the field of building sustainable low-carbon cities (LCC). Previous studies have mainly focused on the national or provincial level, ignoring the problem of heterogeneity among different cities, and the consideration of the influencing factors of low-carbon cities has not been comprehensive enough. Given this, the authors of this paper selected 107 cities in the Yangtze River Economic Belt from 2006 to 2019, constructed a general comprehensive index system for measuring the high-quality development level of low-carbon cities at the prefecture-level city level, and explored the spatial and temporal evolution trends and core drivers of the high-quality development level of low-carbon cities in the Yangtze River Economic Belt using the CRITIC–VIKOR method and an ensemble learning algorithm. The empirical results showed that most of the cities in the Yangtze River Economic Belt showed an overall upward trend in the level of high-quality development and a certain degree of “central collapse” in the spatial distribution. In addition, this paper further confirms that industrial structure is the most central driver of low-carbon urban development, the importance of urban carbon emissions and the level of science and technology innovation are gradually increasing, and a certain aggregation effect is formed in space that has led to a significant urban “siphon effect”. These results provide new evidence on the spatial and temporal evolution of the high-quality development of low-carbon cities in China and can help authorities formulate more targeted policies and strategic plans to enhance the high-quality development of low-carbon cities.

Research on Green Innovation Performance of Manufacturing Industry and Its Improvement Path in China

Green innovation, which combines “innovation-driven” and “green development,” is one of the most powerful ways to overcome resource and environmental constraints and enhance manufacturing industry sustainability. Based on the innovation value chain perspective, the green innovation process of manufacturing industry is decomposed into two stages: green scientific and technological R&D and achievement transformation. Then, using the three-stage DEA and Malmquist index model to measure the green innovation performance of China’s manufacturing industry, and compare its regional heterogeneity from the dual perspectives of static efficiency and dynamic productivity. In addition, this paper further discusses the improvement path of green innovation performance of China’s manufacturing industry. The findings are as follows: (1) The green innovation efficiency of manufacturing industry in China is at a comparatively low degree and has great potential for improvement. Moreover, it shows apparent regional heterogeneity: The green innovation efficiency in the eastern region is higher than that in the western region, and both are higher than that in the center region, confirming the phenomenon of “central collapse”. (2) The green innovation productivity of China’s manufacturing industry shows a “W-type” dynamic evolution tendency, with green technological progress as the key driving factor, while the green technical efficiency does not clearly exhibit a “catch-up effect”. Additionally, it shows significant regional heterogeneity: green innovation productivity in the western region is higher than that in the central and eastern regions, indicating a potential “backwardness advantage”. (3) The eastern region of China is located in combination IV, which indicates that it has a high rate of green innovation efficiency but a low rate of green innovation productivity; the central region is located in combination III, which indicates that it has a low rate of both green innovation efficiency and productivity; and the western region is located in combination II, which indicates that it has a low rate of green innovation efficiency but a high rate of green innovation productivity. Last but not least, this paper puts forward three kinds of paths for the improvement of the green innovation performance of China’s manufacturing industry: unilateral breakthrough, step-by-step and stimulating jumping type.

Analysis of the Spatial Effect of Capital Misallocation on Agricultural Output—Taking the Main Grain Producing Areas in Northeast China as an Example

Increasing agricultural output by reducing capital misallocation is a capital-saving strategy, as it does not require the usage of additional inputs. Based on the panel data of 36 prefecture-level cities in Northeast China from 2011 to 2020, this paper uses the spatial Durbin model to test the impact of capital mismatch on agricultural output and its mechanisms. We found that capital misallocation is prevalent in prefecture-level cities, showing a spatial distribution characteristic of “north-south confrontation and central collapse”, with a significant spatial spillover effect. A one-unit increase in capital misallocation leads to a 16.00% decrease in local agricultural output and a 1.80% decrease in adjacent areas. However, with the optimization and upgrading of the agricultural industry and agricultural technology progress, the inhibitory effect of capital misallocation on the growth of agricultural output is constantly weakening. The above conclusion still holds after a series of robustness tests. The conclusion of this paper provides policy inspiration for promoting the rational allocation of factors between cities and regions, coordinating regional coordinated development, and then promoting the sustainable growth of agricultural output.

Structural and Functional Insight into the Mechanism of Bacillus subtilis 6S-1 RNA Release from RNA Polymerase.

Here we investigated the refolding of Bacillus subtilis 6S-1 RNA and its release from σA-RNA polymerase (σA-RNAP) in vitro using truncated and mutated 6S-1 RNA variants. Truncated 6S-1 RNAs, only consisting of the central bubble (CB) flanked by two short helical arms, can still traverse the mechanistic 6S RNA cycle in vitro despite ~10-fold reduced σA-RNAP affinity. This indicates that the RNA’s extended helical arms including the ‘−35′-like region are not required for basic 6S-1 RNA functionality. The role of the ‘central bubble collapse helix’ (CBCH) in pRNA-induced refolding and release of 6S-1 RNA from σA-RNAP was studied by stabilizing mutations. This also revealed base identities in the 5’-part of the CB (5’-CB), upstream of the pRNA transcription start site (nt 40), that impact ground state binding of 6S-1 RNA to σA-RNAP. Stabilization of the CBCH by the C44/45 double mutation shifted the pRNA length pattern to shorter pRNAs and, combined with a weakened P2 helix, resulted in more effective release from RNAP. We conclude that formation of the CBCH supports pRNA-induced 6S-1 RNA refolding and release. Our mutational analysis also unveiled that formation of a second short hairpin in the 3′-CB is detrimental to 6S-1 RNA release. Furthermore, an LNA mimic of a pRNA as short as 6 nt, when annealed to 6S-1 RNA, retarded the RNA’s gel mobility and interfered with σA-RNAP binding. This effect incrementally increased with pLNA 7- and 8-mers, suggesting that restricted conformational flexibility introduced into the 5’-CB by base pairing with pRNAs prevents 6S-1 RNA from adopting an elongated shape. Accordingly, atomic force microscopy of free 6S-1 RNA versus 6S-1:pLNA 8- and 14-mer complexes revealed that 6S-1:pRNA hybrid structures, on average, adopt a more compact structure than 6S-1 RNA alone. Overall, our findings also illustrate that the wild-type 6S-1 RNA sequence and structure ensures an optimal balance of the different functional aspects involved in the mechanistic cycle of 6S-1 RNA.

Spatial–Temporal Heterogeneity and Driving Factors of Rural Residents’ Food Consumption Carbon Emissions in China—Based on an ESDA-GWR Model

The increase in income among Chinese residents has been accompanied by dramatic changes in dietary structure, promoting a growth in carbon emissions. Therefore, in the context of building a beautiful countryside, it is of great significance to study the carbon emissions of rural residents’ food consumption to realize the goal of low-carbon food consumption. In this paper, the calculation of food consumption carbon emissions of Chinese rural residents is based on the carbon conversion coefficient method, and the spatial heterogeneity of influencing factors is analyzed with the aid of the ESDA-GWR model. The results indicate that the per capita food consumption carbon emissions of rural residents have increased by 1.68% annually, reaching 336.73 kg CO2-eq in 2020, which is 1.32 times that of 2002. Carbon emissions generated from rural residents’ food consumption have significant spatial agglomeration characteristics, showing the spatial distribution characteristics of a north–south confrontation, with a central area collapse. The influencing factors of food consumption carbon emissions have significant spatial heterogeneity, among which, as the main force to restrain the growth of food consumption carbon emissions, the price factor has a regression coefficient between −0.1 and −0.3, and its influence has weakened from northwest to southeast in 2020. The education–social factor is the main driving force for the growth of food consumption carbon emissions, with a regression coefficient between 0.58 and 0.99, and its influence has increased from east to west. In the future, formulating food consumption optimization policies should be based on the actual situation of food consumption carbon emissions in various regions to promote the realization of low-carbon food consumption.

Numerical study on the influence of experimental conditions on the collapse behaviour of stiffened panels

Numerical simulations of stiffened panels under in-plane compressive load are conducted to investigate the influence of experimental conditions on the structural strength and collapse characteristics. The initial geometrical imperfections of the stiffened panels have been measured before the test and are adopted in the numerical analysis. The material properties of the steel in the finite element analysis are determined by tension tests. Using the finite element method, various configurations, including the actual experimental boundary conditions and assumed ideal conditions are considered in the numerical simulations to identify the influence of laboratory conditions. The ultimate strength, structural modulus and collapse behaviour of the stiffened panels in the tests and numerical simulations are compared. The results of the analysis suggest that the translational and rotational degrees of freedom at the end edges of the specimen should be constrained to force the central span collapse first in the three full spans model.

Seismic attribute analysis of Chicxulub impact crater

Chicxulub crater formed ~ 66 Ma ago by an asteroid impact on the Yucatan platform in the southern Gulf of Mexico. The crater has a ~ 200 km rim diameter and has been covered by carbonate sediments up to ~ 1.1 km thick in the central zone. Previous studies have identified the structure and major crater units through geophysical models from seismic reflection and potential field data, classified as the central uplift, terrace zone, outer and inner ring fault zones and impactite deposits. Impact produced a deep excavation cavity, with fragmentation and ejection of large volumes of crustal target rocks. Understanding the pre-existing structures, impact-induced deformation and post-impact processes requires high-resolution images of the crater and target zone. For this study, we use complex trace attributes of instantaneous phase, frequency, envelope amplitude and similarity, in an E-W seismic reflection profile crossing the crater in the marine sector. Geophysical logs and borehole lithological columns from the on-land drilling projects are used to constrain the petrophysical analysis. Seismic attributes aid to characterize the radial fault zones and physical property contrasts, revealing asymmetries in the crater structure. The reflector packages in the post-impact sediments and target Cretaceous sequence are identified in the frequency and phase attributes. The bottom crater reflectors, with the basal sediments filling the crater floor topography, are enhanced with the envelope amplitude attribute. A set of high-amplitude reflectors is shown in the similarity attribute, in which the reflector geometry is delineated on the target carbonate sequence. The offsets in the high-amplitude reflectors between the eastern and western sectors are possibly associated to target pre-impact asymmetries, impact deformation and effects of central crater collapse.

Single-Cut Single-Screw Capitate-Shortening Osteotomy for Kienbock's Disease.

Background Kienbock's disease, in spite of an uncertain natural history, is known to cause lunate compromise, leading to central column collapse, carpal instability, and degenerative arthritis of the wrist. Joint leveling procedures are performed in the early stages of Kienbock's disease to "unload" the lunate. Capitate shortening is the preferred procedure in Kienbock's patients with positive ulnar variance. Description of Technique We describe the rationale and a simplified technique of capitate shortening in early Kienbock's disease. This is a single-cut osteotomy with single-screw stabilization. Patients and Methods We have performed this technique in three cases. We present a case of a 26-year-old male who presented with a 1-year history of pain in his right wrist. Radiology performed demonstrated lunate sclerosis. Diagnostic arthroscopy revealed healthy articular surfaces. Single osteotomy capitate shortening was performed with an oscillating saw and fixed with a single cannulated compression screw. A shortening of 1.5mm was obtained with this technique. Results At 1- to 2-year follow-up, all three patients had considerable pain relief but did not have a complete resolution of pain. There was a significant improvement in function and grip strength. There have been no cases with infection, nonunion, avascular necrosis or a need for a salvage procedure. Conclusion The simplified technique of capitate shortening is easy to perform, less traumatic to the capitate vascularity, and leads to good short-term functional results.

Minor disruptions triggered by supersonic molecular beam injection on J-TEXT tokamak

Disruption mitigation experiments with supersonic molecular beam injection of argon gas on J-TEXT were conducted to explore the evolution process during multistage minor disruption. The corresponding numerical simulation was performed using a 3D magnetohydrodynamic (MHD) code, namely, NIMROD (Sovinec et al 2004 J. Comput. Phys. 195 355). The experimental and numerical simulation results are shown in the following. The central plasma temperature decreases to less than tens of electovolts after a relatively long period of multistage thermal collapse. Different MHD instability modes appear when the impurity cold front propagates toward the q = 2 surface. During the burst of MHD activity and central plasma thermal collapse, the heat flux is transferred from the core region to the plasma boundary. Further numerical simulation results show that the MHD process is accompanied by a significant increase in the core-oriented spread of impurities through the q = 2 surface. During the transition stage from the minor disruption to the major disruption, the high order modes play an important role and the magnitude of the n = 3 growth rate is even larger than that of the n = 1 or n = 2 mode. What seems to separate major from minor disruptions is that in a minor disruption, a single MHD crash is not sufficient to cause a full radiative collapse.

Between a Lift and a Hard Place

Between a Lift and a Hard Place

Simulation Analysis of Mechanical Behavior during Treatment Construction of Tunnel Collapse

Combined with Shenjiashan tunnel collapse accident in Guanggan highway, the paper analyzes the construction simulate the mechanical behavior of rock collapse segment caused stress field, displacement field and variation of the plastic zone calculated by FLAC3D numerical software. The conclusions are as follows: (1) The maximum tensile stress occurs in the vault 60°range and the central backplane while the maximum compressive stress occurs in the middle part of the foot of the tunnel arch; (2) Vault subsidence maximum displacement is mainly distributed in the range of 60°vault, floor uplift maximum displacement is mainly distributed in the 1/3 of the central bottom. (3) As the excavation proceeds, the central cavity collapse begins to appear plastic zone (tensile yield based), the arch plastic zone (shear yield based) significantly increase the scope and depth of rock to develop. If unchecked, the arch part of shear failure may occur. The results show that the support system of advance pipe shed support +cavity grouting reinforcement + steel arch played an active role in the collapse of governance throughout the process, and the foot of the tunnel arch and vault 60°range are the focus of the site in support of this collapse treatment construction.