Protective effect of glutamine pretreatment on ischemia-reperfusion injury of spinal cord in rabbits

Objective To investigate the effect of glutamine (Gln) on the content of reduced glutathione hormone (GSH) and aminoglutaminic acid (Glu) of spinal cord following ischemia-reperfusion injury. Methods Totally 40 healthy adult male rabbits were randomly divided into five groups: sham-operation group (S group), ischemia-reperfusion injury group (I/R group), low-dose glutamine group (L Gln group), median-dose glutamine group (M Gln group) and high-dose glutamine group (H Gln group). After glutamine preconditioning, the model of spinal cord ischemia-reporfasion injury was established according to Zivin's method. The general status of animals was observed and the changes of Jacobs scoring were recorded in each group. Malondialdehydes (MDA), GSH, Glu and superoxide dismutase (SOD) activity in lumbar spinal cord tissues were determined using chemical colorimetry. The neuron number and deviation rate in spinal cord anterior horn were observed histopathologically. Results There was no significant difference between L Gin group and I/R group in behavior scoring, SOD activity, content of MDA and Glu, neuron number and deviation rate of spinal cord (P>0.05); however, there was a significant difference in GSH content of spinal cord (P<0.05). M Gln group and I/R group differed significantly (P<0.05) in behavior scoring, SOD activity, content of MDA, Glu, GSH, neuron number and deviation rate of spinal cord. Between H Gln group and M Gln group, there was no significant difference in behavior scoring, content of MDA and Glu, SOD activity, neuron number and aberration rate in spinal cord (P>0.05), whereas there was a significant difference in SOD activity and Giu content (P<0.05). Conclusion Pretreatment with medium-dose glutamine has a protective effect on spinal cord ischemia-reporfasion injury in rabbits, which may be related to the maintenance of GSH content, increase of SOD activity and reduction of MDA.     

To kill a real option – Incomplete contracts,real options and PPP

This paper is concerned with the implications of public–private partnership agreements for the execution of expansion options in road infrastructure. More specifically, it analyzes the expansion of an existing two-lane road in Sweden, and examines the real options created by an intermediate type of road with three lanes. Interpreting the results from real option analysis in the light of incomplete contract theory, this paper finds that external congestion costs might necessitate public ownership to ensure a social optimal outcome in public–private partnerships.     

Estimating traffic demand risk – A multiscale analysis

This paper proposes a novel method for estimating the traffic demand risk associated with transportation. Using mathematical properties of wavelets, we develop a statistical measure of traffic demand sensitivity with respect to GDP. This measure can be adapted in a flexible way to capture risk levels relevant for different investment horizons. We demonstrate the timescale decomposition of risk with Swedish traffic demand data for 1950–2005. In general, rail transport shows a stronger co-movement with GDP than road transport. Moreover, we examine the volatility exhibited by traffic demand. Our findings suggest that rail investments are more risky than road investments. Since the findings can be used for optimal investment timing and for choice between public investment alternatives, they are deemed important for public policy in general.     

肿瘤免疫研究的回顾与展望

20多年来,本校免疫病理研究室一直从事肿瘤免疫的研究,从研究肿瘤浸润淋巴细胞的活化和肿瘤逃逸的机制开始,到探索诱导浸润淋巴细胞(tumor infiltrating lymphocytes, TIL)活化的最佳条件,并将这些研究结果转化为肿瘤免疫治疗和免疫预防的实践,从一个侧面反映了人类在征服肿瘤道路上的艰苦历程。     

Practicability study on the suitability of artificial,neural networks for the approximation of unknown steering torques

For steer-by-wire systems, the steering feedback must be generated artificially due to the system characteristics. Classical control concepts require operating-point driven optimisations as well as increased calibration efforts in order to adequately simulate the steering torque in all driving states. Artificial neural networks (ANNs) are an innovative control concept; they are capable of learning arbitrary non-linear correlations without complex knowledge of physical dependencies. The present study investigates the suitability of neural networks for approximating unknown steering torques. To ensure robust processing of arbitrary data, network training with a sufficient volume of training data is required, that represents the relation between the input and target values in a wide range. The data were recorded in the course of various test drives. In this research, a variety of network topologies were trained, analysed and evaluated. Though the fundamental suitability of ANNs for the present control task was demonstrated.     

Virtually being there: Human aspects of shore-based ship assistance

Shore-based ship assistance is a topic that increasingly is attracting attention from the maritime community. Subjects such as shore-based pilotage and VTS are often discussed and there is technological and political pressure towards more extensive forms of such assistance. Perhaps less often mentioned, but not less important, is the human side of these subjects. The present paper examines two of the central concerns for the people who actually work within today’s VTS centers, namely communication and trust. The study consisted of a literature review, study visits, observations and interviews. Communication and trust are found to be closely related, and one main finding is that adapting one’s means of communication to the context can be a very powerful (and necessary) tool for the creation of trust. Another important result is that the ability of the shore-based operator to see the situation from the viewpoint of the crew is crucial for the creation and maintenance of trust.     

Direct resolution of the pitch of DNA on positively charged lipid bilayers by frequency-modulation AFM

High resolution structural studies of DNA and DNA binding proteins by atomic force microscopy (AFM) require well-bound samples on suitably flat substrates. Adsorbing the DNA onto a positively charged supported lipid bilayer has previously been shown to be a potentially effective strategy for structural studies with AFM. Here, using our home-built frequency-modulation AFM (FM-AFM), we show that these bilayer substrates are only maximally effective for high resolution AFM when the samples are short, linear DNA, compared with circular plasmid DNA. We find that, with the former sample, the measured width of the DNA is about 2 nm, the known DNA diameter, and there is a clear height modulation along the length of the DNA with a periodicity of about 3.4 nm, in excellent agreement with the known pitch of the double helix. This sample preparation strategy is expected to enable higher resolution studies of DNA and DNA binding proteins with FM-AFM than that can presently be achieved.     

The Teachable Moments on Marine Mammal Tours: Watching versus Swim-With Tours

With the continuing growth of the tourism industry over recent decades, has come a change in tourist behavior from the traditional stereotypical 3-S tourist (sun, sand, sex) to an increasingly sophisticated and demanding tourist. These “new” tourists like to learn about history, nature, and wildlife, and they expect an educational component on wildlife tours. This study investigated swim-with-dolphin tours in Kaikoura, New Zealand with regard to the educational content and the overall anatomy of these tours, using data from observations on a total of 32 tours during December 2011. The resulting data were then compared with the data from Hrycik and Forestell's study, which investigated the content of questions asked by passengers on whale-watching tours in Stellwagen Bank National Marine Sanctuary. Results of the on-tour observations indicate that the surveyed tours display a structured approach to interpretation, which is customized to the specific tour anatomy of a “swim-with” tour, and varies in some parts significantly from “watch-only” tour interpretation.     

Effect of interference fits on the fatigue lives of bolted composite joints

The effect of interference fits on the fatigue lives of bolted composite joints is investigated by conducting mechanical tests. Static and fatigue tests are carried out on specimens made of carbon-bismaleimide composites joined together as double-lap single-bolt joints. The bolts having interference fits ranging of 0 (neat fit), 0.5%, 0.75% and 1% are performed. The results demonstrate the relationship between fatigue life and different values of interference fits. After the fatigue tests, non-destructive evaluation (NDE) and scanning electron microscope (SEM) are used to observe the damage of the surrender and surface of the hole. The test results show that the interference fitted specimens have improved fatigue life compared to the neat fitted specimen. The NDE and SEM results reveal that the damage degree of interference fitted specimen is weaker than that for the neat fitted one.     

发动机冷却风扇气动性能的计算方法

介绍了发动机冷却风扇气动性能的计算方法、建模方法和求解技术。利用CFD软件Fluent计算了某款风扇的静压、功率和效率与流量的关系,试验结果验证了计算结果。通过对风扇内部压力场和速度场的研究,分析了风扇效率低下的原因,并提出了改进方案。计算结果表明,叶尖间隙对风扇性能有重要影响,叶尖间隙过大将导致风扇效率低下,故应减小叶尖间隙或安装圆环以提高风扇性能。