一秒钟成就精彩——从奥尼尔的《绳索》看编剧技巧

《绳索》,一出仅五个角色的独幕剧,题材也并不出奇,无非金钱的魅力盖过亲情,不肖浪子虐待老父而已。然而就是这样一个不起眼的老话题,在青年奥尼尔的笔下却营造出强烈的戏剧效果,成为了兼具观赏性和思想性,足以震撼人们灵魂的佳作。究其缘由,作者超群的编剧技巧从中起了至关重要的作用。该剧主要讲述：农场主本特利老人有一双儿女,其子鲁克早年偷了钱,离家出走。老人大怒,在自家仓库顶棚悬一绳圈,声称若儿子回来,

Suppression strategy for parametrically excited lateral vibration of mass-loaded string

This paper discusses a simple way to suppress the parametrically excited lateral vibration of a mass-loaded string. Supposing that the mass at the lower end of the string is subjected to a vertical harmonic excitation and neglecting the higher order vibration modes, the equation of motion for the mass-loaded string can be represented by a Mathieus equation with cubic nonlinearity. According to the theory of the Mathieus equation, in the mass-loaded string system, when the vertical vibration frequency of the mass approaches twice the natural frequency of the string lateral vibration, once the vertical vibration amplitude of the mass exceeds a critical value, the parametric resonance will occur in the string. To avoid the parametric resonance, a vibration absorber, composed of a thin beam and two mass blocks attached at both sides of the beam symmetrically, is proposed to install with the mass to reduce its vertical vibration, and ultimately suppress the lateral vibration of the string. Such a suppression strategy is finally validated by experiments.

走进真实的四川凉山

“悬崖村”到底有几多?“辍学儿童”有那么多吗?凉山,留给人们的是一个极端落后的印象。实际上,这些都是过去的凉山。认识大凉山,并非一件易事。说她美丽、富饶,说她贫穷、落后,似乎都对。四川省西昌市邛海边,在凉山彝族奴隶社会博物馆内,矗立有一座巨大的雕塑,姑且把雕塑叫《绳索》。

Differences in neuroplasticity after spinal cord injury in varying animal models and humans

Rats have been the primary model to study the process and underlying mechanisms of recovery after spinal cord injury. Two weeks after a severe spinal cord contusion, rats can regain weight-bearing abilities without therapeutic interventions, as assessed by the Basso, Beattie and Bresnahan locomotor scale. However, many human patients suffer from permanent loss of motor function following spinal cord injury. While rats are the most understood animal model, major differences in sensorimotor pathways between quadrupeds and bipeds need to be considered. Understanding the major differences between the sensorimotor pathways of rats, non-human primates, and humans is a start to improving targets for treatments of human spinal cord injury. This review will discuss the neuroplasticity of the brain and spinal cord after spinal cord injury in rats, non-human primates, and humans. A brief overview of emerging interventions to induce plasticity in humans with spinal cord injury will also be discussed.

Microsurgical efficacy in 326 children with tethered cord syndrome: a retrospective analysis

Tethered cord syndrome is a progressive disease with a typically insidious onset in infants and children, and which can lead to persistent progress of neurological deficits and a high rate of disability without timely intervention. The purpose of this study was to investigate the curative effect of microsurgery in children with different types of tethered cord syndrome. In this study, we analyzed 326 patients with tethered cord syndrome, aged from 2 months to 14 years old, who were followed for 3-36 months after microscopic surgery. Based on clinical manifestations and imaging findings, these patients were classified into five types： tight ilium terminale （53 cases）, lipomyelome- ningocele （55 cases）, lipomatous malformation （124 cases）, postoperative adhesions （56 cases）, and split cord malformation （38 cases）. All patients underwent microsurgery. Curative effects were measured before and 3 months after surgery by Spina Bifida Neurological Scale based on sensory and motor functions, reflexes, and bladder and bowel function. The results showed that Spina Bifida Neurological Scale scores improved in all five types after surgery. Overall effective rates in these patients were 75%. Effective rates were 91% in tight ilium terminale, 84% in lipomyelomeningocele, 65% in lipomatous malformation, 75% in postoperative adhesion, and 79% in split cord mal- formation. Binary logistic regression analysis revealed that types of tethered cord syndrome （lipoma-type or not） and symptom duration before surgery were independent influencing factors of surgical outcome. These results show that therapeutic effect is markedly different in patients with different types of tethered cord syndrome. Suitable clinical classification for tethered cord syndrome will be helpful in predicting prognosis and guiding treatment. This trial has been registered in the Chinese Clinical Trial Registry （registration number： ChiCTR1800016464）.

Effect of Acupuncture on Free Radicals in Rats with Early Experimental Spinal Cord Injury

Effect of acupuncture on free radicals after spinal cord injury was observed in rats with experimental spinal cord injury (SCI). Results indicated that within 24 hours after SCI malondialdehyde (MDA) increased progressively, 2 hours after SCI it reached the peak; and the superoxide dismutase (SOD) activity decreased significantly at the same hours, the decrease being the most marked 2-6 hours after SCI. The MDA content in the acupuncture group was significantly lower (P

Dynamic model for internally carried air-launched rocket

For rigid-flexible coupling multi-body with variable topology,such as the system of internally carried air-launched or heavy cargo airdrop,in order to construct a dynamic model with unified form,avoid redundancy in the modeling process and make the solution independent,a method based on the equivalent rigidization model was proposed.It divides a system into independent subsystems by cutting off the joints,of which types are changed with the operation process of the system.And models of different subsystems can be constructed via selecting suitable modeling methods.Subsystem models with flexible bodies are on the basis of the equivalent rigidization model which replaces the flexible bodies with the virtual rigid bodies.And the solution for sanction,which is based on the constraints force algorithm(CFA)and vector mechanics,can be independent on the state equations.The internally carried air-launched system was taken as an example for verifying validity and feasibility of the method and theory.The dynamic model of aircraft-rocket-parachute system in the entire phase was constructed.Comparing the modeling method with the others,the modeling process was programmed;and form of the model is unified and simple.The model,method and theory can be used to analyze other similar systems such as heavy cargo airdrop system and capsule parachute recovery system.

Adaptive fuzzy design of a rope attitude adjustment system

The attitude adjustment of rope system faces the challenging due to the difficulty in obtaining accurate three-dimensional(3D)mathematical model and solving by traditional methods.A set of adjustment systems is designed and used to investigate the automatic control for level or preset attitude adjustment of unknown weights and eccentric loads.The system principle and characteristics are analyzed.The 3D model is decomposed into two two-dimensional(2D)subsystems,and an adaptive fuzzy controller based on BP neural network and least squares(LSE)is designed.The simulation experiment uses MATLAB to train the level-adjustment data for testing algorithm,and a small load is used to verify the effectiveness of the system.The experimental results show that precise attitude adjustment can be achieved within the system load range,and the response speed is fast.This adjustment method provides a fast and effective method for precise adjustment of the load attitude.

绳索寓言的魅力

儿子曾经是个自私的家伙，最明显的表现就是不愿意为他人服务。

Unilateral hemilaminectomy for patients with intradural extramedullary tumors

A modified hemilaminectomy was introduced in an attempt to explore the operative techniques and the values of the limited approach to spinal cord tumors.Forty-five consecutive patients with intradural extramedullary lesions,who underwent modified hemilaminectomy,were studied retrospectively.The intraspinal tumors were removed via the limited bone window with a 3.3-cm mean length (range: 2.0–6.5 cm) and a 1.2-cm mean width (range: 0.6–1.5 cm),in which the inner parts of the medial and lateral laminae were mostly undercut for wider view.Spinal lesions were cervical in 21 cases,thoracic in 12 cases,lumbar in 10 cases,and multiple in 2 cases.Forty-three cases were completely excised via hemilaminectomy alone.Two subjects with dumbbell neurinoma underwent two-stage tumor removal via anterolateral cervical approach following hemilaminectomy.With respect to neurological status,the percentage of good Frankel scale (D+E grade) was markedly improved from 22.2% on admission to 93.3% at follow-up.At the median 26-month follow-up evaluation by magnetic resonance imaging (MRI),none of the subjects showed spinal deformity or instability.By preserving musculoligamentous attachments and posterior bony elements as much as possible,the modified approach is minimally invasive and may be routinely used to remove intradural and extramedullary tumors,especially in patients with meningiomas and neurinomas.

Potential immunotherapies for traumatic brain and spinal cord injury

Traumatic injury of the central nervous system （CNS） including brain and spinal cord remains a leading cause of morbidity and disability in the world. Delineating the mechanisms underlying the secondary and persistent injury versus the primary and transient injury has been drawing extensive attention for study during the past few decades. The sterile neuroinflammation during the secondary phase of injury has been frequently identified substrate underlying CNS injury, but as of now, no conclusive studies have determined whether this is a beneficial or detrimental role in the context of repair. Recent pioneering studies have demonstrated the key roles for the innate and adaptive immune responses in regulating sterile neuroinflammation and CNS repair. Some promising immunotherapeutic strategies have been recently developed for the treatment of CNS injury. This review updates the recent progress on elucidating the roles of the innate and adaptive immune responses in the context of CNS injury, the development and characterization of potential immunotherapeutics, as well as outstanding questions in this field.

Human placenta-derived mesenchymal stem cells loaded on linear ordered collagen scaffold improves functional recovery after completely transected spinal cord injury in canine

Traumatic spinal cord injury(SCI) is a major challenge in the clinic. In this study, we sought to examine the synergistic effects of linear ordered collagen scaffold(LOCS) and human placenta-derived mesenchymal stem cells(hPMSCs) when transplanted into completely transected beagle dogs. After 36 weeks observation, we found that LOCS+hPMSCs implants promoted better hindlimb locomotor recovery than was observed in the non-treatment(control) group and LOCS group. Histological analysis showed that the regenerated tissue after treatment was well integrated with the host tissue, and dramatically reduced the volume of cystic and chondroitin sulfate proteoglycans(CSPGs) expression. Furthermore, the LOCS+hPMSCs group also showed more neuron-specific βIII-tubulin(Tuj-1)-and NeuN-positive neurons in the lesion area, as well as axonal regeneration, remyelination and synapse formation in the lesion site. Additionally, dogs in the LOCS+hPMSCs group experienced enhanced sprouting of both ascending(CGRP-positive) sensory fibers and descending(5-HT-and TH-positive) motor fibers at the lesion area. All these data together suggested that the combined treatment had beneficial effects on neuronal regeneration and functional improvement in a canine complete transection model. Therefore, LOCS+hPMSCs implantation holds a great promise for bridging the nerve defect and may be clinically useful in the near future.

Complete canine spinal cord transection model: a large animal model for the translational research of spinal cord regeneration

Traumatic spinal cord injury (SCI) usually results in devastating neurologic deficits and disability. In the United States,approximately 12,500 new cases are reported each year, while an estimated 100,000–140,000 new cases occur every year in China (National Spinal Cord Injury Statistical Center, 2016).Spinal cord injuries are highly disabling and primarily affect young adults, and therefore create great psychological and financial burden on the affected individuals and their families.

Application of the sodium hyaluronate-CNTF scaffolds in repairing adult rat spinal cord injury and facilitating neural network formation

The present study aimed to explore the potential of the sodium hyaluronate-CNTF (ciliary neurotrophic factor) scaffold in activating endogenous neurogenesis and facilitating neural network re-formation after the adult rat spinal cord injury (SCI). After completely cutting and removing a 5-mm adult rat T8 segment, a sodium hyaluronate-CNTF scaffold was implanted into the lesion area. Dil tracing and immunofluorescence staining were used to observe the proliferation, differentiation and integration of neural stem cells (NSCs) after SCI. A planar multielectrode dish system (MED64) was used to test the electrophysiological characteristics of the regenerated neural network in the lesioned area. Electrophysiology and behavior evaluation were used to evaluate functional recovery of paraplegic rat hindlimbs. The Dil tracing and immunofluorescence results suggest that the sodium hyaluronate-CNTF scaffold could activate the NSCs originating from the spinal cord ependymal, and facilitate their migration to the lesion area and differentiation into mature neurons, which were capable of forming synaptic contact and receiving glutamatergic excitatory synaptic input. The MED64 results suggest that functional synapsis could be established among regenerated neurons as well as between regenerated neurons and the host tissue, which has been evidenced to be glutamatergic excitatory synapsis. The electrophysiology and behavior evaluation results indicate that the paraplegic rats’ sensory and motor functions were recovered in some degree. Collectively, this study may shed light on paraplegia treatment in clinics.

Effect of electroacupuncture on E-prostanoid 2 expression in the spinal cord in rats with neuropathic pain

OBJECTIVE: To observe the effect of electroacupuncture(EA) treatment on the expression of E-prostanoid 2(EP2) in the spinal cord using a rat model of neuropathic pain, and to examine the effect of different acupuncture prescriptions.METHODS: Rats were randomly divided into six groups: a normal group, model group, sham group,EA 1 group(distal-proximal acupoints), EA 2 group(proximal acupoints), and EA 3 group(distal acupoints). Rats in the EA groups were treated for20 min, once daily for 7 days. The mechanical withdrawal threshold was evaluated at 1 day preoperatively and at 3, 5, and 7 days postoperatively. At 7days postoperatively, hematoxylin-eosin(HE) staining was used to investigate spinal morphological changes. Spinal EP2 messenger ribonucleic acid(m RNA) was detected using reverse-transcription polymerase chain reaction.RESULTS: After the EA treatment, the mechanical withdrawal threshold was up-regulated compared with the model group(P < 0.05). The expression of EP2 m RNA was up-regulated in the spinal cord on day 7 after surgery(P < 0.05). EA stimulation tended to down-regulate EP2 m RNA expression compared with the model group(P > 0.05). The EA 1and EA 2 groups showed a larger treatment effect than the EA 3 group. The HE results showed that EA can improve spinal histomorphology induced by neuropathic pain.CONCLUSION: EA had a strong analgesic and anti-inflammatory effect. The therapeutic effect of EA on the down-regulation of spinal EP2 m RNA expression may be greater when either local acupoints or a distal-proximal combination of acupoints are used than when distal points are used.

Case Report:Congenital spinal intradural arachnoid cyst associated with intrathoracic meningocele in a child

Congenital spinal intradural arachnoid cyst associated with intrathoracic meningocele is very rare.We report a case in a 9-year-old Chinese boy who presented with a two-week history of progressive paraparesis and gait ataxia.Magnetic resonance imaging revealed that a dorsal intradural extramedullary cystic lesion extended from T1 to T5 and compressed the spinal cord.A left lateral intrathoracic meningocele pouch was found incidentally at the level of T1.The arachnoid cyst as well as meningocele was removed and the spinal cord compression was relieved.Arachnoid cyst was confirmed by histological examination.The patient recovered well postoperatively.This is the second report of such a case in the world according to the available literature.The take-home message for our case is that the surgical approach should be individualized,depending on the size and location.