Preoperative risk factors for early extremity blood supply after repair of major arterial injury / 中华创伤骨科杂志

Objective:To investigate the preoperative risk factors affecting early extremity blood supply after repair of major arterial injury so as to provide clues for prevention of limb ischemia.Methods:The clinical data were retrospectively analyzed of the 139 patients (140 extremities) with major extremity arterial injury who had been admitted to Department of Microsurgery, Orthopaedic Trauma and Hand Surgery, The First Hospital Affiliated to Sun Yat-sen University from January 2003 to December 2019. There were 112 males and 27 females, with a mean age of 30 (20, 44) years. The primary outcome was the early status of blood supply to the injured extremity (48 hours after surgery). Univariate analysis was conducted of such factors as gender, age, ischemia time, injury mechanism, injury site, fracture, soft tissue lesion, and duration of surgery. The significant factors ( P<0.1) were then analyzed by logistic regression, and P<0.05 was considered statistically significant. Results:Ischemia happened in 44 (31.4%, 44/140) extremities within 48 hours after surgery. There were significant differences in injury mechanism, ischemia time, fracture, and soft tissue lesion between patients with and without postoperative extremity ischemia ( P<0.05). Logistic regression analysis indicated that blunt injury ( OR=5.639, 95% CI: 1.068 to 29.761, P=0.042) and soft tissue lesion ( OR=12.568, 95% CI: 3.402 to 46.431, P<0.001) were significant preoperative risk factors affecting the early blood supply after repair of major extremity arterial injury. Conclusion:As blunt injury and soft tissue defect are preoperative risk factors for early extremity ischemia after repair of major extremity arterial injury, surgeons should pay more attention to them when assessing patients and making repair protocols.

Progress in Biomechanics of Pelvic Fractures / 医用生物力学

In recent years, with the increase of traffic accidents and the further development of aging, the incidence of pelvic fracture is gradually increasing. Based on the in-depth study about biomechanics of pelvic fracture fixation, the surgical treatment has been widely carried out. The purpose of surgical treatment is to effectively reduce and fix the fracture, correct deformity, restore integrity and stability of the pelvis, and minimize the complications caused by internal and external fixation. How to improve stability of the pelvis while ensuring therapeutic effect is a problem that every doctor will face in clinic. This paper summarizes the biomechanical research progress of pelvic fracture in recent years from the aspects of anatomy, normal biomechanics, classification and biomechanics of pelvic fracture fixation, so as to provide some references for reasonable treatment of pelvic fracture.

Development and Validation for Thoracic-Abdominal Finite Element Model of Chinese 5th Percentile Female with Detailed Anatomical Structure / 医用生物力学

Objective To predict and assess biomechanical responses and injury mechanisms of the thorax and abdomen for small-sized females in vehicle collisions. Methods The accurate geometric model of the thorax and abdomen was constructed based on CT images of Chinese 5th percentile female volunteers. A thoracic-abdominal finite element model of Chinese 5th percentile female with detailed anatomical structure was developed by using the corresponding software. The model was validated by reconstructing three groups of cadaver experiments (namely, test of blunt anteroposterior impact on the thorax, test of bar anteroposterior impact on the abdomen, test of blunt lateral impact on the chest and abdomen). Results The force-deformation curves and injury biomechanical responses of the organs from the simulations were consistent with the cadaver experiment results, which validated effectiveness of the model. Conclusions The model can be used for studying injury mechanisms of the thorax and abdomen for small-sized female, as well as developing small-sized occupant restraint systems and analyzing the forensic cases, which lays foundation for developing the whole body finite element model of Chinese 5th percentile female.

Mechanisms of mid-thoracic spine fracture/dislocation due to falls during horse racing: A report of two cases / 中华创伤杂志(英文版)

We reported two cases of jockeys who sustained fracture/dislocation of the mid-thoracic spine due to traumatic falls during horse racing. We examined the injury mechanism based upon the patients' diagnostic images and video footage of races, in which the accidents occurred. Admission imaging of patient 1 (a 42 years old male) revealed T5 burst fracture with bony retropulsion of 7 mm causing complete paralysis below T5/6. There existed 22° focal kyphosis at T5/6, anterolisthesis of T5 relative to T6, T5/6 disc herniation, cord edema and epidural hemorrhage from T4 through T6, and cord injury from C3 through C6. Admission imaging of patient 2 (a 23 years old male) revealed T4/5 fracture/dislocation causing incomplete paralysis below spinal level. There existed compression fractures at T5, T6, and T7; 4 mm anterior subluxation of T4 on T5; diffuse cord swelling from T3 through T5; comminuted fracture of the C1 right lateral mass; right frontal traumatic subarachnoid hemorrhage; and extensive diffuse axonal injury. The injuries were caused by high energy flexion-compression of the mid-thoracic spine with a flexed posture upon impact. Our results suggest that substantially greater cord compression occurred transiently during trauma as compared to that documented from admission imaging. Video footage of the accidents indicated that the spine buckled and failed due to abrupt pocketing and deceleration of the head, neck and shoulders upon impact with the ground combined with continued forward and downward momentum of the torso and lower extremities. While a similar mechanism is well known to cause fracture/dislocation of the cervical spine, it is less common and less understood for mid-thoracic spine injuries. Our study provides insight into the etiology of fracture/dislocation patterns of the mid-thoracic spine due to falls during horse racing.

Estimation Method for Optimal Length of Hamstring Muscles in vivo / 医用生物力学

Objective To build a method for calculating the optimal length of hamstring muscles in vivo, and make comparison with other indirect parameters which represent the optimal length. Methods By synchronously recording knee flexion torque and kinematic data, the musculoskeletal model of lower limbs was built to obtain hamstring strength and muscle length, and to further calculate the optimal length of hamstring muscles. Results Flexion angle at peak knee flexion torque was significantly greater than that at peak hamstring strength and their correlation coefficient was 0.741. The optimal lengths of each bi-articulated hamstring muscles were significantly greater than the corresponding muscle lengths during standing and their correlation coefficients was low. Conclusions The established estimating method for optimal length of hamstring muscles provided references for future studies on injury mechanism and risk factors. Flexion angle at peak knee flexion torque could partly represent the optimal length of hamstring. It is not suggested that hamstring muscle length during standing should be used as an approximation of hamstring optimal length.

In-depth discussion on the treatment of terrible triad of the elbow / 中国组织工程研究

BACKGROUND: The diagnosis and treatment of the terrible triad of the elbow have achieved a breakthrough. OBJECTIVE: To introduce the definition, basic anatomy, stable structure, injury mechanism and classification of terrible triad of the elbow, and to discuss the treatment plan deeply. METHODS: The first author searched PubMed, CNKI and Wanfang databases for the articles published before September 2019. The keywords were “terrible triad of the elbow, elbow joint, fracture dislocation” in English and Chinese, respectively. A large number of articles concerning the terrible triad of the elbow in recent years were reviewed, and the treatment strategy was summarized. RESULTS AND CONCLUSION: For the terrible triad of the elbow, the operator must carefully check the patient before operation, carefully analyze the imaging examination results and three-dimensional printed model, and accurately judge the bone structure of the elbow and degree of ligament injury. During the operation, the stability of the radial head, the fracture of the coronoid process and the injury of the lateral ligament complex are usually reconstructed through a single lateral approach or a combination of internal and external approaches. Then, the stability of elbow joint is tested to determine whether it is necessary to repair the medial ligament complex or use the hinged external fixator to restore the stability of elbow joint. Early active rehabilitation is needed. The above systematic treatment can reduce postoperative complications, accelerate fracture healing, and improve elbow joint function and patients’ quality of life.

Reconstruction of Vehicle-pedestrian Collision Road Traffic Accidents Based on PC-Crash Software / 法医学杂志

Objective To discuss the application value of vehicle-pedestrian collision road traffic accidents reconstruction based on PC-Crash software in forensic identification. Methods A case of vehicle-pedestrian collision was chosen based on a tachograph, then PC-Crash software was applied to construct a vehicle-pedestrian collision model, and reconstruct the vehicle-pedestrian collision road traffic accident. Finally, the process of vehicle-pedestrian collision was reproduced. Results In accident reconstruction, when the car speed was lower than 50km/h, the landing point of the pedestrian after collision was in the front of the car. When the car speed was higher than 50 km/h, after collision, the pedestrian flipped towards the car roof and landed behind the car. With the increase of vehicle speed, throwing distance of the pedestrian increased continuously. When the vehicle collision speed reached 60 km/h, the experimental results in this case were basically consistent with the actual situation of the case. Head acceleration of the pedestrian was at the maximum （1 655.70 m/s2） at 0.080 s. Chest acceleration of the pedestrian increased from 597.63 m/s2 to the peak 675.52 m/s2 at 0.055-0.060 s. Tibia acceleration of the pedestrian increased from 759.26 m/s2 to the first peak 1 367.06 m/s2, then reached the maximum speed （1 718.19 m/s2） at 1.225 s. Conclusion The process of vehicle-pedestrian collision road traffic accidents can be reconstructed based on PC-Crash software under a situation of limited conditions, and can further clarify the speed of the vehicle, the location and degree of human body injury as well as the mechanism of damage of the pedestrian in the accident. Therefore, PC-Crash software has a certain practical value in forensic identification of road traffic accidents.

Research Progress about the Effect of Obesity on Occupant Impact Injury Mechanism / 医用生物力学

Modern vehicle safety design and safety regulations are mostly based on 50th percentile populations. However, with the increase of obese populations, it is very important to investigate the injury mechanism and protection of obese occupant. Methods such as traffic accidents statistics, cadaver experiments, multi-body modeling and finite element modeling, are currently used to study the injury mechanism of obese occupants. Different hypotheses including cushion effect, body geometrical effect and mass increasing effect have been put forward to explain the effect of obesity on occupant injury mechanism, which means that its mechanism is still uncertain. The impact injury mechanisms of obese occupant were comprehensively summarized. Furthermore, the problems confronted by the research of current obese occupant impact injury and future investigations were proposed in this study.

Inference on Injury Mechanism of Ankle Fracture by Lauge-Hansen Classification / 法医学杂志

OBJECTIVES@#To explore the injury mechanism of ankle fracture inferred by the Lauge-Hansen classification with the application of medical imageology and its application value in forensic medicine.@*METHODS@#A total of 32 ankle fracture cases with known injury mechanism were collected from January 2013 to May 2018, which were identified in Yongkang Public Security Bureau, Zhejiang Province. The Lauge-Hansen classification of ankle fracture was performed by three forensic experts based on the data of X-ray and CT image. Fisher's exact test and Kappa consistency analysis were performed by SPSS 20.0 statistical software to compare the results of the Lauge-Hansen classification with the injury mechanism of ankle fracture obtained through the criminal evidence.@*RESULTS@#In 32 cases, 84.4% （27/32） ankle fractures were classified according to the Lauge-Hansen classification based on medical imaging. The mechanism of ankle fracture identified by the Lauge-Hansen classification was consistent with that obtained through the criminal evidence.@*CONCLUSIONS@#Based on medical imaging, the Lauge-Hansen classification can be well applied to infer the injury mechanism of ankle fracture in part cases, and provide objective evidence for the crime scene reconstruction of criminal cases.

Research progress on hyperextension tibial plateau fractures / 中国修复重建外科杂志

Objective: To summarize the progress in the treatment of hyperextension tibial plateau fractures.

Analysis on the Injury Mechanism and Characteristics of Ox Horn / 法医学杂志

OBJECTIVES@#To study the morphological characteristics of the injury caused by ox horn on human body and its injury mechanism, and to discuss the rules and characteristics of injury by ox horn and provide forensic evidences for identification of such cases.@*METHODS@#The comparative analysis of position and morphological characteristics were performed by summarizing the data of 100 victims gored by ox accepted by Heilongjiang agricultural areas public security bureau during 2004-2014.@*RESULTS@#The specific injuries only could be found at the contact positions such as thorax and abdomen, lower back and limbs of the victims gored by ox horn. Most of the skin wounds had the characteristics of sharp injuries, the bar-type injury by club which called "rail way bruise" was an obvious characteristic appeared on the soft tissue.@*CONCLUSIONS@#Ox horn can cause non-specific injuries on thorax and abdomen, lower back and limbs of human body, which are similar with the characteristics of sharp injury and injury by club. Careful analyzation and identification should be performed on such injury in daily work.

Advances in research on microwave radiation effects on inner ears / 军事医学

Inner ear is one of the most sensitive parts to microwave radiation.The effect of microwave radiation on the inner ear system is its damage to the vestibule and cochlea.The vestibular and cochlear injury is closely related to the balance of the human body and hearing loss.This article reviews the mechanism of microwave and effects of microwave radiation on the structure and function of the inner ear in order to provide data for future related research.

Research progress of Hoffa fracture / 中华外科杂志

Hoffa fracture is a rare type of fracture confined to the coronal plane of the femoral condyle. High-energy is a common reason of Hoffa fracture, and low-energy trauma and iatrogenic injury can also cause Hoffa fracture in some cases. The commonly used classifications include Letenneur classification, CT classification, AO classification and modified AO classification. X-ray is the first choice to diagnose Hoffa fractures, fracture lines can be found. If the X-ray is negative, CT scan and MRI should be performed. Nondisplaced fractures can be managed conservatively with cast immobilization, however, there is high risk of redisplacement. Open reduction and internal fixation is preferred. For the young patient with good compliance, a simple medial or lateral condylar fractures can be treated via medial or lateral parapatellar approach. When the fracture is exposed, the headless compression screws can be inserted vertical to the fracture line from backward to forward. For a bicondylar fracture, median parapatellar incision can be selected. While for a complex fracture with osteoporosis or high body mass index, cannulated screws with anti-sliding plate fixation technique should be used.

The research on biomechanics of sports injuries / 医用生物力学

All professional or amateur athletes sustain different kinds of acute or overused injuries, which vary with sports events. Biomechanics plays the key role in determining risk factors and elucidating injury mechanisms for sports injuries. Three kinds of research methods, experimental test, modeling and computer simulation and statistical simulation, are generally used in biomechanical studies of sports injuries. This paper firstly reviews the epidemiology of sports injuries, and then comprehensively summarizes the related researches on injury biomechanics, in purpose of providing theoretical basis for studies on sports injury biomechanics, prevention of sports injuries, and clinical treatments and rehabilitation.

Open reduction and internal fixation for capitellum fractures in adolescents / 中华创伤骨科杂志

Objective To report the clinical outcomes of open reduction and internal fixation for capitellum fractures in adolescents.Methods From January 2010 to January 2015,14 adolescents with capitellum fracture were admitted to our department.They were 12 males and 2 females,aged from 12 to 16 years (13.7 years).By the Dubberley classification,we had 2 cases of type ⅠA,8 cases of type ⅡA,3 cases of type Ⅲ A and one of type Ⅲ B.We summarized their clinical characteristics and injury mechanisms.At the last follow-up,the therapeutic efficacy was assessed by the Mayo elbow function scores,and the ranges of motion of the elbow and forearm on the affected side were recorded.Results The 14 patients obtained an average follow-up of 12 months (from 6 to 18 months).All the cases achieved fracture union within 3 months,but malunion appeared in one.At the last follow-up,the ranges of flexion and extension of the affected elbow averaged 120.6° (from 110° to 135°),and the ranges of lateral rotation of the affected forearm averaged 160.3° (from 150° to 175°).According to the Mayo scores at the last follow-up,the elbow function was rated as excellent in 12 and as good in one.Mild traumatic arthritis occurred in 3 cases.Conclusions Capitellum fractures in adolescents are often Dubberley type A ones without a complicated fracture of the posterior condyle.Usually,the capitellum is impacted by the radial head in the process of elbow extension with valgus stress.After definite diagnosis,open anatomical reduction and reasonable and reliable internal fixation can result in good clinical results.

Forensic Analysis of the Characteristics of Pelvic Fracture in 65 Road Traffic Accident Death Cases / 法医学杂志

OBJECTIVES@#To analyze the characteristics and mechanisms of pelvic fractures in the cases of road traffic accident deaths.@*METHODS@#Total 65 cases of road traffic accident deaths with pelvic fracture were collected, and the sites, characteristics and injury mechanisms of pelvic fracture were statistically analyzed.@*RESULTS@#Among the 65 cases of pelvic fracture, 38 cases of dislocation of sacroiliac joint were found, and most combined with pubis symphysis separation or fracture of pubis. In the fractures of pubis, ischium and acetabulum, linear fractures were most common, while comminuted fractures were most common in sacrum and coccyx fractures. There were 54 cases combined with pelvic soft tissue injury, and 8 cases with pelvic organ injury and 44 cases with abdominal organ injury. In the types of pelvic ring injury, 32 cases were separation, 49.32%, followed by compression, 26.15% and only one case was verticality, 1.54%.@*CONCLUSIONS@#Detailed and comprehensive examination of the body and determination of the pelvic fracture type contribute to analyze the mechanisms of injury.

Fracture morphology and injury mechanisms of tibial plateau fracture: analysis of 200 cases / 中华创伤骨科杂志

Objective To classify tibial plateau fractures based on the analysis of the morphology and injury mechanisms of 200 cases of tibial plateau feature.Methods We collected the X-ray and CT images of 200 consecutive cases of tibial plateau fracture in i99 patients who had been treated at our department from January 2010 to April 2011.They were 134 males and 65 females,from 15 to 77 years of age (average,45.7 years).According to the Schatzker classification,9 cases were type Ⅰ (4.5％),105 type Ⅱ (52.5％),19type Ⅳ (9.5％),37type Ⅴ (18.5％),30type Ⅵ (15.0％),and none type m.The fracture morphology and injury mechanism of each case were analyzed to propose a new classification system.Results Fractures of tibial plateau can be classified into the following five types:(a) Lateral condylar fracture and valgus injury (100 cases,50％).The injury mechanism is the axial force on the valgus and extended knee joint.(b) Fracture-dislocation injury (24 cases,12.0％).This type includes typical Schatzker type Ⅳ,and some cases of Schatzker type Ⅵ associated with lateral subluxation.Its mechanism is a compound force of valgus,varus,rotational and axial stresses.The rotational force is the key factor leading to subluxation of the knee joint.(c) Double-condylar fracture (40 cases,20.0％).This type is caused by an axial force on the extended knee,including Schatzker type Ⅴ and some cases of Schatzker type Ⅵ not associated with knee subluxation.(d) Posterior condylar fracture and flexion injury (32 cases,16.0％).This type only involves the posterior condylar plateau,and is caused by an axial force on the flexed knee.Based on the morphology,posterior condylar fractures can be further divided into three subtypes:simple split of posteromedial condyle,simple collapse of posterolateral condyle,and a combination of the two.(e) Frontal plateau compression fracture and hyperextension injury (4 cases,2.0％).This type is caused by an axial force on the hyper-extended knee.It is characterized by significant compression of the anterior plateau and intact posterior plateau.Conclusion Based on the morphological features and injury mechanisms,tibial plateau fractures can be classified into 5 types:lateral condylar fracture,fracture-dislocation injury,double-condylar fracture,posterior condylar fracture,and frontal plateau compression fracture.

Injury Mechanism of Scaphoid Fracture：Forensic Analysis of 43 Cases / 法医学杂志

Objective To explore the key points of injury mechanism of scaphoid fracture in forensic ex-pertise and to provide the references for forensic practices. Methods Forty-three cases of injury mecha-nismidentification of scaphoid fracture were selected from2007 to 2011 in Institute of Forensic Evi-dence, Chinese Criminal Police Academy. Following aspects were analyzed:missed diagnosis and misdi-agnosis at first visit, fracture classifications, accompanying injuries and mechanismof injury. Results The rates of missed diagnosis and misdiagnosis were high in the cases of scaphoid fractures, most common in the fracture of the waist. The disagreement on mechanismof injury was whether it was due to direct impact or indirect effect by falling. Conclusion wrist hyperextension due to fall with palmimpact on the ground was the main cause of scaphoid fracture.

Effects of low-dose T-2 toxin on cultured cartilage cells and molecular mechanism / 中华地方病学杂志

Objective Through observing the effect of low-dose T-2 toxin on chondrocyte,to study the molecular mechanism of cartilage damage.Methods The primary chondrocytes were isolated from articular cartilage of d 1-2 Wistar neonate rats through enzymatic digestion.Different doses (0.005,0.010,0.100 μg/L) of T-2 toxin were added after 24 h in vitro culture.The survival rate of chondrocytes was detected with Trypan blue staining.Echylosis (matrix metalloproteinase,MMP1) was analyzed by immunohistochemistry.The damage of articular chondrocyte was observed by transmission electron microscope.Results ①Cell morphology of in vitro cultured chondrocyte:the newly isolated chondrocytes were spherical.After 24 hours,the adherent cells gradually began to stretch the triangle or polygon;the nucleus was large and round;the cell was clear and transparent,containing secretory granules.②Cell proliferation:T-2 toxin had a significant inhibitory effect on chondrocyte proliferation,the higher the concentration of T-2 toxin,the significant the inhibitory effects [0.000 μg/L (control) group:3.45 × 108/L,0.005 μg/L T-2 toxin group:3.45 × 108/L,0.010 μg/L T-2 toxin group:2.06 × 108/L,x2 =9.554,P ＜ 0.05].③Immunohistochemical observation:dysplasia,nucleus condensation and membrane rupture were observed in T-2 toxin treated group,brown staining was observed in all groups at varying degrees.The deepest staining was in 0.005 μg/L T-2 toxin group,with the strongest secretion of MMP1;with increasing doses of the toxin,the damage to cartilage cells was severe,MMP1 secretion was less,staining was weak,and the weakest staining was in the 0.100 μg/L T-toxin group.④Under transmission electron microscopy:in control group,cytoplasm was rich in rough endoplasmic reticulum,nuclear membrane and cell membrane were clear;in 0.005 μg/L T-2 toxin group,the cell nucleus showed pyknosis,organelles were decreased in cytoplasm;in 0.100 μg/L T-2 toxin group,the microvilli was dropped out of cartilage surface,nuclear changes were obvious,and mitochondria was myeloid degeneration;rough endoplasmic reticulum was degranulation and expansion into cystiform,chondrocytes were apoptosis occasionally,the cell nucleus showed pyknosis,and the formation of high-density plaque.Conclusion Low dose of T-2 toxin could damage the primary cultured articular chondrocyte in vitro.The results have showed that there are damaged cytostasis,chondrocyte degeneration,necrosis and apoptosis.

A retrospective analysis of 374 casualties from the Nepal earthquake / 中华急诊医学杂志

Objective To analyze the feature of victims transported from Nepal Pokhara's earthquake,and summarized the rescuing experiences got by the Chinese government medical team.Methods A total of 374 casualties from the 2015 Nepal's earthquake magnitude 8.1 transported to the Field Hospital of the Chinese government medical team were classified into four groups according to different causes of injury,and then retrospectively analyzed the types of injury,vital signs,severity of injury and causes of injury.Results Of 374 casualties,the average age was (30.1 ± 12.4) years,and were divided into group A (n =154) in which casualties trapped under ruined buildings,group B (n =123) in which the victims had crushed injury during escaping with their lives,group C (n =58) in which the wounded had injury resulted from fall on the ground during fleeing for their lives and group D (n =39) in which the injury of casualties was caused by fall from high level.Of them,273 patients (296 parts of body injured) suffered from fracture including 34 patients with severe multiple trauma.The average age in the group D (22.3 ±7.4 years old) was significant younger compared with the others (all P ＜ 0.05).The average age in the group C (48.4 ± 13.3 years old) was significant older compared to the others (all P ＜ 0.05).The injury probability was higher for male in the group D (14.2％ vs.7.1％,x2 =5.077,P =0.024) and the injury probability was higher for female in the group C (19.7％ vs 10.8％,x2 =5.635,P =0.018).The incidence of limbs fracture was highest (66.6％) in all 296 parts of body injured.The incidence of skull fracture in the group B (31.6％) was higher compared to the others (all P＜0.05),and the incidence of spinal fracture in the group D (40.0％) was higher compared to the others (all P ＜ 0.05).There was no significant difference in the severe multiple trauma incidence between the group A and the group D (16.9％ vs.12.8％,x2 =0.381,P =0.537),but both group A and group D had significant higher incidence of severe multiple trauma compared to the rest two groups (all P ＜ 0.05).The wound debridement was the leading rate of treatment among variety of treatments (57.5％) and the plaster fixation was the second high rate of treatment (30.9％),and the wound infection was found in 25 patients (17.4％) at the first dressing among 144 patients with soft tissue laceration.After active and regular debridement,72％ patients' wound smear tests were negative 3 days later,and 100％ were negative 7 days later.Conclusions The casualties treated by Chinese government medical team had relatively young average age,not very severe critical illness,and quite high rate of wound infection.The treatment of all kinds of fractures and open wound was a matter of critical importance.Although facing the challenge of incomplete set of medical equipment,the lacking of medicine and many other unexpected problems,the Chinese government medical team successfully fulfilled the mission with the prior experience accumulated from several domestic earthquake disaster rescue actions.