Unstable evolution of railway slope under the rainfall-vibration joint action

Understanding the unstable evolution of railway slopes is the premise for preventing slope failure and ensuring the safe operation of trains.However,as two major factors affecting the stability of railway slopes,few scholars have explored the unstable evolution of railway slopes under the joint action of rainfall-vibration.Based on the model test of sandy soil slope,the unstable evolution process of slope under locomotive vibration,rainfall,and rainfall-vibration joint action conditions was simulated in this paper.By comparing and analyzing the variation trends of soil pressure and water content of slope under these conditions,the change laws of pore pressure under the influence of vibration and rainfall were explored.The main control factors affecting the stability of slope structure under the joint action conditions were further defined.Combined with the slope failure phenomena under these three conditions,the causes of slope instability resulting from each leading factor were clarified.Finally,according to the above conclusions,the unstable evolution of the slope under the rainfall-vibration joint action was determined.The test results show that the unstable evolution process of sandy soil slope,under the rainfall-vibration joint action,can be divided into:rainfall erosion cracking,vibration promotion penetrating,and slope instability sliding three stages.In the process of slope unstable evolution,rainfall and vibration play the roles of inducing and promoting slide respectively.In addition,the deep cracks,which are the premise for the formation of the sliding surface,and the violent irregular fluctuation of soil pressure,which reflects the near penetration of the sliding surface,constitute the instability characteristics of the railway slope together.This paper reveals the unstable evolution of sandy soil slopes under the joint action of rainfall-vibration,hoping to provide the theoretical basis for the early warning and prevention technology of railway slopes.

PFNA2 versus 95 Degree Condylar Blade Plate in the Management of Unstable Trochanteric Fractures

Purpose: The proximal femoral nail anti-rotation (PFNA) is known to have advantages in enhancing the anchorage ability of internal fixation in elderly unstable osteoporotic intertrochanteric fracture patients. However whether it is superior to condylar blade fixation is not clear. This study aimed to determine which treatment has better clinical outcomes in older patients. Materials and Methods: A total of 86 patients over the age of 60 with unstable trochanteric fractures within the past 3 weeks, were included in this prospective study conducted from June 1, 2018, to May 31, 2021. All the intertrochanteric fractures were classified according to AO/OTA classification. Among them, 44 cases were treated with the Proximal Femoral Nail (PFNA2) with or without an augmentation screw, and 42 cases were treated with the Condylar Blade Plate. In addition, the operative time, intraoperative blood loss, intraoperative and postoperative blood transfusion, postoperative weight-bearing time, hospitalization time, Harris score of hip function, Kyle’s criteria and postoperative complications were compared between the two groups. Results: The mean duration of surgery for the PFN group was 66.8 minutes (on average), whereas for the condylar blade plate group, it was 99.30 minutes (on average). The PFNA2 group experienced less blood loss (average of 80 mL) compared to the condylar blade plate group (average of 120 mL). Union and partial weight-bearing occurred earlier in the PFNA2 group (14.1 weeks and 10.6 weeks, respectively) compared to the Condylar blade plate group (18.7 weeks and 15.8 weeks). In two patients from the PFNA2 group, screw backing out and varus collapse complications were encountered;however, these patients remained asymptomatic and did not require revision surgery. In two other patients, screw cut out and breakage of the nail at the helical screw hole leading to non-union of the proximal femur were observed during the nine-month follow-up, necessitating revision surgery with prosthetic replacement. Among the condylar blade plate group, three patients experienced complications, including blade breakage at the blade and plate junction. In two cases, the fracture united in varus, and in one case, the blade cut through, resulting in non-union of the femoral head, which required revision surgery. According to the Harris hip score and Kyle’s criteria, a good-excellent outcome was observed in 92.85% of cases in the PFNA2 group and 90.90% of cases in the condylar blade plate group. Conclusion: Both the Proximal Femoral Nail A2 and Condylar blade plate are effective implants for the treatment of unstable trochanteric fractures. The intramedullary implant promotes biological healing and allows for early ambulation with minimal complications. Similarly satisfactory restoration of anatomy and favorable radiological and functional results can be achieved with the biological fixation provided by the 95-degree condylar blade plate. However, the use of PFNA2 internal fixation technique has the advantage of less trauma in elderly patients than the 95-degree condylar blade plate.

Analysis of the Nursing Effect of Continuity of Care on Elderly Patients with Coronary Heart Disease Unstable Angina and its Impact on Quality of Life

Objective:To analyze the effect of using continuity of care for elderly patients with coronary heart disease(CHD)with unstable angina pectoris(UAP)and its impact on their quality of life.Methods:100 cases of elderly patients with CHD with UAP admitted to our hospital from March 2022 to March 2023 were selected and grouped into an observation group and a control group of 50 cases each according to the randomized number table method.The nursing effect and quality of life of the observation group(continuity nursing)and the control group(routine nursing)were compared.Results:The total effective rate of nursing care was 96.00%observation group and 80.00%for the control group,and the differences were significant(χ2=6.061,P<0.05).Patients in the observation group had fewer episodes(1.42±0.21)times/week and a shorter duration(5.46±0.39)min,which were better than the control group(t=3.465,2.973;P<0.05).The depression self-rating depression scale(SDS)score(42.16±6.64)and anxiety self-rating scale(SAS)score(32.26±7.35)in the observation group were lower and the quality of life was higher as compared to that of the control group(P<0.05).Conclusion:Continuous nursing care improved the nursing effect of elderly CHD with UAP patients,promoted the alleviation of UAP symptoms,improved patient mentality,and improved their quality of life.Hence,continuous nursing care possesses significant clinical application value.

Structural Determination,Unstable Antiferromagnetism and Transport Properties of Fe-Kagome Y_(0.5)Fe_(3)Sn_(3) Single Crystals

Kagome materials have been studied intensively in condensed matter physics.With rich properties,various Kagome materials emerge during this process.Here,we grew single crystals of Y_(0.5)Fe_(3)Sn_(3)and confirmed an YCo_(6)Ge_(6)-type Kagome-lattice structure by detailed crystal structure characterizations.This compound bears an antiferromagnetic ordering at T_(N)= 551 K,and shows a weak ferromagnetism at low temperatures,where an anomalous Hall effect was observed,suggesting the non-zero Berry curvature.With the unstable antiferromagnetic ground state,our systematic investigations make Y_(0.5)Fe_(3)Sn_(3)a potential Kagome compound for Kagome or topological physics.

Application of lesser trochanteric reduction fixator in the treatment of unstable intertrochanteric fractures

BACKGROUND Closed reduction and internal fixation with intramedullary nails has been widely accepted for treating intertrochanteric fractures.AIM To focus on how to avoid displacement of the lesser trochanter in unstable intertrochanteric fractures.METHODS We developed a lesser trochanteric reduction fixator for treating intertrochanteric fractures through fixing the lesser trochanter by combining the loop plate through the fixator after reduction by the reducer.Five patients with intertrochanteric fractures treated with the newly developed lesser trochanteric reduction fixator and loop plate combined with intramedullary nails,and 20 patients with intertrochanteric fractures treated with simple intramedullary nails were selected from December 2020 to March 2021.RESULTS The postoperative Harris hip score was significantly higher in patients treated with the lesser trochanteric reduction fixator than in patients treated without the lesser trochanteric reduction fixator,which indicated that this lesser trochanteric reduction fixator had a positive impact on rehabilitation of the hip joint after surgery and could significantly improve the quality of life of patients.CONCLUSION We fully realize the significance of trochanteric reduction and fixation,namely,reconstruction of structures under pressure,in the treatment of intertrochanteric fractures.As long as the general condition of patients is favorable and they are willing to undergo surgery,fixation of the main fracture end should be performed and the lesser trochanter should be reduced and fixed at the same time.

Internal fixator vs external fixator in the management of unstable pelvic ring injuries:A prospective comparative cohort study

BACKGROUND Reconstruction of the pelvic ring anatomy in unstable anterior pelvic ring injuries is a significant step to reduce the mortality rate associated with these injuries efficiently.There is a debate on using either an anterior subcutaneous pelvis internal fixator(INFIX)or an anterior supra-acetabular external fixator(EXFIX)to manage an unstable anterior pelvic ring fracture.AIM To compare the functional and radiological outcomes and complications of INFIX vs EXFIX in managing unstable pelvic ring injuries.METHODS A prospective cohort study included 54 patients with unstable pelvic ring fractures.The patients were divided into two groups;the INFIX group,in which 30 cases were fixed by INFIX,and the EXFIX group,in which 24 patients were treated by EXFIX.The average age in the EXFIX group was 31.17 years(16-57 years),while in the INFIX group,it was 34.5 years(17-53 years).The study included 20(66.7%)males and 10(33.3%)females in the INFIX group and 10(41.7%)males and 14(58.3%)females in the EXFIX group.The radiological outcomes were evaluated using Matta and Tornetta's score,and the functional outcomes using the Majeed score.RESULTS The results revealed a statistically significant difference between both groups(P=0.013)regarding radiological outcomes,according to Matta and Tornetta's score in favor of the INFIX group.Sitting,standing,and walking abilities were measured at a 3-mo follow-up visit using Majeed score modules.It was significantly better among the INFIX group than the EXFIX group in all three modules.At the final follow-up,both groups had no statistically significant difference according to the Majeed score;92.35 in the INFIX group and 90.99 in the EXFIX group(P=0.513).A lower surgical site infection rate was noticed in the INFIX group(P=0.007).CONCLUSION Anterior subcutaneous pelvis INFIX is associated with better radiological outcomes and a lower infection rate than anterior supra-acetabular EXFIX in managing patients with unstable anterior pelvic ring fractures.

Effects of surgical treatment modalities on postoperative cognitive function and delirium in elderly patients with extremely unstable hip fractures

BACKGROUND As the perioperative risk of elderly patients with extremely unstable hip fractures(EUHFs)is relatively high and therapeutic effect is not satisfactory,new therapeutic strategies need to be proposed urgently to improve the efficacy and clinical outcomes of such patients.AIM To determine the influence of two surgical treatment modalities on postoperative cognitive function(CF)and delirium in elderly patients with EUHFs.METHODS A total of 60 elderly patients consecutively diagnosed with EUHF between September 2020 and January 2022 in the Chongqing University Three Gorges Hospital were included.Of them,30 patients received conventional treatment(control group;general consultation+fracture type-guided internal fixation),and the other 30 received novel treatment(research group;perioperative multidisciplinary treatment diagnosis and treatment+individualized surgical plan+risk prediction).Information on hip function[Harris hip score(HHS)],perioperative risk of orthopedic surgery[Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity(POSSUM)],CF[Montreal cognitive assessment scale(MoCA)],postoperative delirium[mini-cognitive(Mini-Cog)],adverse events(AEs;internal fixation failure,infection,nonunion,malunion,and postoperative delirium),and clinical indicators[operation time(OT),postoperative hospital length of stay(HLOS),ambulation time,and intraoperative blood loss(IBL)]were collected from both groups for comparative analyses.RESULTS The HHS scores were similar between both groups.The POSSUM score at 6 mo after surgery was significantly lower in the research group compared with the control group,and MoCA and Mini-Cog scores were statistically higher.In addition,the overall postoperative complication rate was significantly lower in the research than in the control group,including reduced OT,postoperative HLOS,ambulation time,and IBL.CONCLUSION The new treatment modality has more clinical advantages over the conventional treatment,such as less IBL,faster functional recovery,more effectively optimized perioperative quality control,improved postoperative CF,mitigated postoperative delirium,and reduced operation-related AEs.

Surgical Management of Unstable Superior Femoral Epiphysiolysis with Great Displacement

Introduction: Superior femoral epiphysiolysis (SFE) is a most progressive but sometimes abrupt displacement of the femoral head relative to the superior femoral metaphysis through the cervicocerebral growth plate of the femur. The displacement of the femoral head is most often downward and backward. It is a typical pathology of the pubescent adolescent, most often overweight. It occurs on average at the age of 12 years in girls and 14 years in boys. Unstable forms with large displacements have a high risk of femoral head necrosis and chondrolysis. Although in situ fixation is the generally accepted treatment for minor SFE, the treatment of more severe cases remains controversial. When the extent of the displacement makes it impossible to pass a screw between the femoral neck and the femoral head, the only option is to reduce the displacement. This reduction must be gentle, progressive and limited to the minimum necessary for osteosynthesis. Objective: The aim of the work was to evaluate the results of the technique of progressive reduction of epiphyseal displacement by transtibial traction followed by percutaneous fixation of the femoral head by screw. Patients and Method: This was a retrospective descriptive study over a 10-years period from January 1, 2013 to December 31, 2022. It focused on the surgical treatment of unstable upper femoral epiphysiolysis with large displacement in the orthopaedic trauma department of the University Hospital of Kati. All patients operated on in our department for large displacement SFE were included in this study. Cases of secondary large displacement upper femoral epiphysiolysis and patients who had already undergone surgery on the proximal femur were excluded. Continuous progressive traction on the Boppe splint through a pin under the anterior tibial tuberosity was performed for 15 days in all patients. The hip was flexed to 45° and the knee to 35°. Fixation was performed with one or two screws. No contralateral preventive fixation was performed. Minimum follow-up was one year. Functional outcome was assessed by the Postel Merle d’Aubigné score. Anatomical outcome was assessed by the quality of reduction, the occurrence or non-occurrence of femoral head necrosis, and chondrolysis. Results: We identified nine patients with a mean age of 12.8 years and extremes of 9 and 17 years. There were three boys and six girls. Trauma was mentioned in four cases. The cause was idiopathic in five cases. Functional impotence was complete in all patients. The slippage was acute on a chronic background in all patients. The left side was affected in 7 cases and the right side in 2 cases. The patients were overweight in 7 cases. The patient’s weight was within the normal range in two cases. At final follow-up, all nine patients were asymptomatic. Anatomically, all nine patients had a femoral head free of avascular necrosis. In eight patients, the posterior tilt was absent, identical to that obtained after the traction period. Only one patient had a moderate posterior tilt with a neck uncovering of less than 25%. Functionally, the PMA score was very good in eight cases and good in one case. Conclusion: This study shows that the treatment of acute and unstable forms of upper femoral epiphysiolysis by progressive reduction with transtibial traction can lead to satisfactory results. Reduction in large displacement forms should be gentle, progressive and limited to the minimum necessary for osteosynthesis. Magnetic resonance imaging examination is an essential and indispensable prognostic element. Indications for preventive fixation should be selectively reserved for specific cases.

Strategies for Advancing Road Construction Slope Stability: Unveiling Innovative Techniques for Managing Unstable Terrain

This comprehensive review paper explores various aspects of geotechnical engineering, with a focus on the management of unstable terrains, numerical methods for solving complex soil and consolidation problems, rheological analysis of suspensions and muddy soils, and stability analysis of slopes. It begins by examining the unique physicochemical properties of cohesive sediments, including cohesion and specific surface area. The temporal evolution of deposit concentration and average bed concentration in unstable terrains is discussed, along with settling behavior of isolated particles and hindered settling using empirical equations. Key sedimentation theories, such as Kynch’s theory, and geotechnical consolidation theories, including Terzaghi’s consolidation equation and Gibson’s theory, are presented. The investigation interrelates these theories and principles to offer a holistic view of managing unstable terrains. It also addresses the challenges associated with experimental determination of constitutive relationships and presents alternative simplification methods proposed by researchers. Additionally, it delves into numerical methods for solving nonlinear partial differential equations governing soil behavior, emphasizing the need for numerical frameworks and discussing various techniques and associated challenges. The rheological analysis section covers material flow behavior, rheological behavior models, and the rheological properties of water and cohesive sediment mixtures. Fundamental geotechnical calculations, constitutive laws, and failure criteria are explained, highlighting their relevance in geotechnical engineering applications. This paper provides a multidimensional perspective on geotechnical engineering, offering valuable insights into soil properties, consolidation processes, numerical methods, rheological analysis, and slope stability assessment for professionals in the field.

Identifying Metabolite and Protein Biomarkers in Unstable Angina In-patients by Feature Selection Based Data Mining Method

Unstable angina（UA） is the most dangerous type of Coronary Heart Disease（CHD） to cause more and more mortal and morbid world wide. Identification of biomarkers for UA at the level of proteomics and metabolomics is a better avenue to understand the inner mechanism of it. Feature selection based data mining method is better suited to identify biomarkers of UA. In this study, we carried out clinical epidemiology to collect plasmas of UA in-patients and controls. Proteomics and metabolomics data were obtained via two-dimensional difference gel electrophoresis and gas chromatography techniques. We presented a novel computational strategy to select biomarkers as few as possible for UA in the two groups of data. Firstly, decision tree was used to select biomarkers for UA and 3-fold cross validation was used to evaluate computational performanees for the three methods. Alternatively, we combined inde- pendent t test and classification based data mining method as well as backward elimination technique to select, as few as possible, protein and metabolite biomarkers with best classification performances. By the method, we selected 6 proteins and 5 metabolites for UA. The novel method presented here provides a better insight into the pathology of a disease.

MmWave Beamforming for UAV Communications with Unstable Beam Pointing

Millimeter wave(mmWave) communications of unmanned aerial vehicles(UAVs) have drawn dramatic attentions for its flexibility on a variety of applications.Recently,channel tracking base on the spatial features has been proposed to solve the problem of beam misalignments due to the UAV navigation.However,unstable beam pointing caused by the non-ideal beam tracking environment may impact the performance of mmWave systems significantly.In this paper,an improved beamforming method is presented to overcome this shortcoming.Firstly,the effect of the beam deviation is analyzed through the establishment of the equivalent data rate.Then,combining the quantification of spatial angle and the improved orthogonal matching pursuit(OMP) algorithm,an optimized beam corresponding to the beam deviation is obtained.Simulation results show that the optimized beam of the proposed approach can effectively improve the spectral efficiency without improving the complexity when the beam pointing is unstable.

Unstable Tropical Air-Sea Interaction Waves and Their Physical Mechanisms

In this paper, the tropical air-sea interaction is discussed by using a simple air-sea coupled model, in which the inertia-gravity waves are filtered off and only the equatorial Rossby waves are reserved in both the atmosphere and the ocean. There exist two kinds of air-sea interaction waves in the coupled model, that is, the high-frequency fast waves and the low-frequency slow waves. The phase speed of the fast waves is westward and the frequencies are close to those of the equatorial Rossby waves in the atmosphere. The slow waves propagate westward in the part of short wavelengths and eastward in that of long wavelengths. There exist instabilities for both the westward and eastward propagating slow waves. If the fast waves are filtered off, there is little effect on the slow waves which have great influence on the long range process in the tropical air-sea coupled system. According to the tropical air-sea interaction waves we obtain here, a possible explanation to the propagating process of ENSO events is given.

Asymmetrical traumatic bilateral hip dislocations with hemodynamic instability and an unstable pelvic ring: Case report and review of literature

Simultaneous anterior and posterior traumatic dislocations of both hips are very rare. Only 33 cases have been previously reported in the English language literature. Although they were all due to high-energy injuries, they were hemodynamically stable and had a stable pelvic ring. We report a unique case of asymmetrical hip dislocations with an unstable pelvic ring and hemodynamic instability. A 40-year-old man was injured in a high-energy motor vehicle accident. He was hemodynamically unstable when he presented in the emergency department. Radiolographs showed asymmetrical dislocations of both hips with an unstable pelvic ring. Under general anesthesia, he had closed reduction of the dislocations of both hips, followed by temporary stabilization with an external fixator. Transcatheter arterial embolization was performed to stop active pelvic bleeding. Delayed open reduction and internal fixation was performed 12 d later with anterior and posterior plates. The patient recovered well with an uneventful post-operative course. Asymmetrical bilateral hip dislocations with pelvic ring instability caused by trauma, as presented in this case, is very rare and potentially life threatening. Prompt treatment can give a good outcome.

Plasma Levels of the Anti-inflammatory Cytokine IL-10 and Inflammatory Cytokine IL-6 in Patients with Unstable Angina

The plasma levels of inflammatory cytokine interleukin-6 （IL-6） and anti-inflammatory cytokine interleukin-10 （IL-10） in the patients with unstable angina or stable angina were determined and compared. In 30 patients with unstable angina and 22 patients with stable angina, plasma levels of IL-10 and IL-6 were detected by ELISA and plasma lipid parameters by lipid research clinical methods respectively. The results showed plasma levels of IL-10 were significantly lower in unstable angina group than in stable angina group （P=0. 005）, while those of IL-6 were significantly increased in unstable angina group as compared with those in stable angina group （P= 0. 039）. There was a significantly negative correlation between IL-10 and IL-6 in patients with unstable angina （r=-0.41, P=0. 003）. In the unstable angina group, IL-6 levels were obviously positively correlated with TC （r=0. 314, P=0. 023）, but not with TG and HDL. There were no significant correlations between IL-10 and plasma lipid parameters. It was suggested that the decreased IL-10 and increased IL-6 might be associated with the atheromatous plaque stability and progression of coronary heart diseases. IL-10 may play an important role in preventing coronary vascular lesions.

Study on Effect of Zhixinkang Capsule(脂欣康胶囊)in TreatingUnstable Effort Angina and Hyperlipidemia and Its Function in Vascular Endothelium Protection

Objective:To observe the clinical effect and protection of vascular endothelium of Zhixin-kang Capsule (ZXKC) in middle-aged and old people with unstable effort angina and hyperlipidemia. Methods: Sixty-five patients with unstable effort angina were randomly divided into ZXKC group (34 cases) and control group (31 cases). Conventional western medical therapy was given to both groups, with ZXKC group receiving additional ZXKC treatment. Data of 20 healthy persons were taken as normal group. Forty-eight patients with hyperlipidemia were divided into ZXKC group treated with ZXKC (31 cases) and control group treated with Yixintong (17 cases). The changes of clinical symptoms and laboratory indexes in all the patients were observed before and after treatment. Results: In patients with unstable effort angina, the efficacy of treatment of ZXKC, the withdrawal rate of nitroglycerin, the relieving of symptoms, the improvement of the electrocardiogram, the counts of circulating endothelial cells, the content of platelet P-selectin, the content of plasma endothelin (ET), the activity of superoxide dismutase (SOD) and the activity of malonyldialdehyde (MDA) were all better than those in the control group. In patients with hyperlipidemia, there was no significant difference in lipids reduction between ZXKC group and the control group. In both groups, the total cholesterol (TC), triglyceride (TG), low density lipo-protein-cholesterol (LDL-C), lipoprotein(a) [Lp(a)] , ET, oxidized low density lipoprotein, MDA, arte-riosclerotic index (AI) all lowered obviously, while the SOD, HDL-C and calcitonin gene-related peptide (CGRP) were all elevated markedly. In the ZXKC group, the nitric oxide(NO) increased significantly whereas the ET/CGRP and ET/NO decreased markedly. The total effective rate in symptom relieving, the markedly effective rate, the reduction of TC, ET and ET/CGRP, and the elevation of SOD in ZXKC group were all superior to those in the control group. Conclusion: ZXKC could effectively resist myocardial ischemia, relieve angina, reduce blood lipids, protect vascular endothelial cells, inhibit the activation of platelets, and resist lipid peroxidation.

An innovative bio-engineering retaining structure for supporting unstable soil

The paper presents a new prefabricated bio-engineering structure for the support of unstable soil.This prefabricated structure is made of a steel frame which is completely filled with soil and a face made of tree trunks among which scions or autochthonous bushes are planted.Due to the difficulties in interpreting the complex interaction between soil and structure during the installation and lifetime,an in situ test was carried out in order to evaluate the state of stress in the steel frame and to understand the global behavior of the structure under service loads.On the basis of the obtained results,a procedure for checking the structure safety was proposed and discussed.An easy design method was developed during the research.Moreover,the use of this type of prefabricated structure shows several advantages,such as good performances in terms of stabilizing effects,and easy assembly and transport.

Control of static unstable airframes

The challenge and control problems of static unstable missiles are presented. The steady-state benefits of static instability are illustrated, while the corresponding control challenge is described both by the characteristic lag of airframe and the increment of necessary control usage. Control limitation led by unstable zero-pole pair is analyzed for preliminary design and evaluation. Linear control strategy is examined wherein two and three loop acceleration autopilots with different control usages are developed using an optimal control approach combined with frequency domain constraint. The weights selection and relation with system performance are detailed. Then the nonlinear backstepping recursive method is detailed to determine how well it is able to follow command and its engineering feasibility. The results show that a static unstable missile is controllable, while the actuator bandwidth is the crucial limited factor. There should be a compromise between overall performance and actuator payment.

Multi-slice spiral computed tomography in diagnosing unstable pelvic fractures in elderly and effect of less invasive stabilization

BACKGROUND Older people are more likely to experience pelvic fractures than younger people.Multi-slice spiral computed tomography(CT)uses three-dimensional(3D)reconstruction technology to generate 3D images that can clearly demonstrate the 3D space of fractures and detect fractures at a higher rate.AIM To investigate the clinical value of multi-slice spiral CT 3D reconstruction in the diagnosis of unstable pelvic fractures in the elderly as well as the effect of less invasive stabilization.METHODS A total of 86 patients with unstable pelvic fractures treated between March 2016 and March 2019 underwent femoral supracondylar bone traction before surgery.Pelvic radiography and multi-row spiral CT were performed successively once the patient’s vital signs and hemodynamic indices were stable.Secondary processing of the original data was performed to obtain 3D reconstruction images and determine the vertical displacement of the pelvis.After basic or complete reduction,minimally invasive internal fixation using hollow lag screws was performed.The detection rates of fracture location and classification by X-ray and CT reconstruction were compared.Patients were divided into two groups according to the presence or absence of preoperative 3D reconstruction to compare postoperative reduction,wound healing time,fracture healing time,hospitalization time,visual analog scale(VAS)score,poor internal fixation,and functional recovery.RESULTS The diagnostic coincidence rates of X-rays for pubic symphysis,ilium wing,sacroiliac periarticular,and sacral fractures were lower than those of CT reconstruction.The coincidence rate of CT reconstruction in the clinical classification of pelvic fractures was 100%,whereas 11 cases were misdiagnosed by X-ray;the total coincidence rate was 87.21%.The total excellent and good rates of postoperative reduction were significantly higher in the study group than in the control group(P<0.05).The wound healing,fracture healing,and hospitalization times were significantly shorter in the study group than in the control group(P<0.05).The VAS scores decreased in both groups postoperatively and were lower in the study group than in the control group(P<0.05).The total incidence of poor postoperative internal fixation was significantly lower in the study group than in the control group(P<0.05).The overall rate of postoperative functional recovery was significantly higher in the study group than in the control group(P<0.05).CONCLUSION Multi-slice spiral CT has high guiding significance for the diagnosis,classification,and treatment of unstable pelvic fractures in the elderly.Preoperative 3D reconstruction can effectively shorten the operation time and promote fracture healing,while minimally invasive internal fixation can effectively reduce pain and promote functional recovery of fracture sites,making it worthy of clinical application.

Stability and Robust Stability of Switched Positive Linear Systems With All Modes Unstable

This paper is concerned with the stability and robust stability of switched positive linear systems(SPLSs) whose subsystems are all unstable. By means of the mode-dependent dwell time approach and a class of discretized co-positive Lyapunov functions, some stability conditions of switched positive linear systems with all modes unstable are derived in both the continuous-time and the discrete-time cases, respectively. The copositive Lyapunov functions constructed in this paper are timevarying during the dwell time and time-invariant afterwards. In addition, the above approach is extended to the switched interval positive systems. A numerical example is proposed to illustrate our approach.

Stability of coal pillar in gob-side entry driving under unstable overlying strata and its coupling support control technique

Considering the situation that it is difficult to control the stability of narrow coal pillar in gob-side entry driving under unstable overlying strata, the finite difference numerical simulation method was adopted to analyze the inner stress distribution and its evolution regularity, as well as the deformation characteristics of narrow coal pillar in gob-side entry driving, in the whole process from entry driving of last working face to the present working face mining. A new method of narrow coal pillar control based on the triune coupling support technique (TCST), which includes that high-strength prestressed thread steel bolt is used to strain the coal on the goaf side, and that short bolt to control the integrity of global displacement zone in coal pillar on the entry side, and that long grouting cable to fix anchor point to constrain the bed separation between global displacement zone and fixed zone, is thereby generated and applied to the field production. The result indicates that after entry excavating along the gob under unstable overlying strata, the supporting structure left on the gob side of narrow coal pillar is basically invalid to maintain the coal-pillar stability, and the large deformation of the pillar on the gob side is evident. Except for the significant dynamic pressure appearing in the coal mining of last working face and overlying strata stabilizing process, the stress variation inside the coal pillar in other stages are rather steady, however, the stress expansion is obvious and the coal pillar continues to deform. Once the gob-side entry driving is completed, a global displacement zone on the entry side appears in the shallow part of the pillar, whereas, a relatively steady fixed zone staying almost still in gob-side entry driving and present working face mining is found in the deep part of the pillar. The application of TCST can not only avoid the failure of pillar supporting structure, but exert the supporting capacity of the bolting structure left in the pillar of last sublevel entry, thus to jointly maintain the stability of coal pillar.