Analysis on the stability of traffic flow with the information of two preceding cars

The stability analysis is one of the important problems in the traffic flow theory, where the congestion phenomena can be regarded as the instability and the phase transition of a dynamical system. An extended optimal velocity model is deduced by considering the effect of the information of two leader cars. The stability condition of the extended model is obtained by using the linear stability theory. The modified Korteweg-de Vries (mKdV) equation is derived to describe the traffic behavior near the critical point by applying the nonlinear analysis. The numerical simulation results demonstrate the analytical results and show that the traffic congests are suppressed more efficiently by considering two vehicles ahead. Therefore, the next-nearest-neighbor car has strong effects on traffic dynamics and plays an important role on stabilizing the traffic flow.     

桑树施春肥若干问题的磋商

本省地处长江三角洲,土壤气候适宜栽桑,养蚕、蚕茧产量高,质量好,尤其是春季。因此,广大蚕农对桑树施春肥历来特别重视,随着技术进步,养蚕次数增多,亩桑产茧量也逐步提高,桑地的施肥量逐年增加,近年来春肥的施用量越来越多,但肥效较低,笔者对此进行了试验,现将结果报告如下:     

依靠科技进步 发展饲料添加剂

依靠科技进步发展饲料添加剂化工部饲料添加剂中心傅同禄傅萍我国的饲料添加剂工业兴起于８０年代。饲料添加剂诞生于改革开放的大潮中，在经济腾飞的过程中发展，没有经历过经济转轨的阵痛，由国营、集体、个体、合资、独资企业等种种经济成分组成。１９９６年我国的饲料...     

探讨以实践能力为主的“NIIT”教育模式

通过四个方面介绍NIIT教育与传统高校教育的区别，以及其先进的国际教育模式。     

80%氟虫腈WG防治水稻纵卷叶螟试验初报

80%氟虫腈WG是上海农乐生物制品股份有限公司生产的一种高含量的氟虫腈新剂型,为验证该药对水稻纵卷叶螟的防治效果、适宜剂量及对作物的安全性,笔者于2006年7月进行田间小区试验,现将结果报道如下。1材料与方法1.1供试药剂80%氟虫腈WG(上海农乐生物制品股份有限公司);5%锐劲特     

Responses of the methanogenic pathway and fraction of CH4 oxidization in a flooded paddy soil to rice planting

Rice planting (RP) is significant to methane (CH₄) emissions from paddy fields, but its effect on the relative contribution of the acetoclastic methanogenesis to total CH₄ production (F_ac) and the fraction of CH₄ oxidized (F_ox) is poorly understood. To quantify the responses of the F_ac and F_ox to RP, we investigated CH₄ fluxes, CH₄ production and oxidation potentials, dissolved CH₄ concentrations, and their stable carbon isotopes in a flooded paddy soil. The mcrA and pmoA gene copies were also determined by quantitative polymerase chain reaction (qPCR). Compared with the unplanted soil (control, CK), the seasonal CH₄ emissions from the planted soil were significantly enhanced, 13.6 times, resulting in large decreases in the CH₄ concentrations in the soil solution. This indicated that much more CH₄ was released into the atmosphere by the RP than was stored in the soils. Acetoclastic methanogenesis became more important from the tillering stage (TS) to the ripening stage (RS) for the CK, with F_ac values increased from 17%–20% to 46%–55%. With RP, the F_ac values were enhanced by 10%–20%, and it significantly increased the copy numbers of the mcrA gene at the four rice stages (TS, booting stage (BS), grain-filling stage (GS), and RS). Furthermore, the effect of the RP on the abundance of the mcrA gene was highly concurrent with the effect on the F_ac values. At the TS, the F_ox values at the soil-water interface were around 50%–75% for the CK, being 15%–20% lower than those of the RP in the rhizosphere. It increased to 65%–100% at the GS, but was reduced by 20%–30% after the RP. These differences might be because the copy numbers of the pmoA gene were significantly raised at the TS while lowered at the GS by the RP. This was further demonstrated by the strong correlations between the effect of the RP on the abundance of the pmoA gene and the effect on the F_ox values. These findings suggest that RP markedly impacts on the abundances of the mcrA and pmoA genes, affecting the pathway of CH₄ production and the fraction of CH₄ oxidization, respectively.     

Wolbachia establishment and invasion in an Aedes aegypti laboratory population

A proposed strategy to aid in controlling the growing burden of vector-borne disease is population replacement, in which a natural vector population is replaced by a population with a reduced capacity for disease transmission. An important component of such a strategy is the drive system, which serves to spread a desired genotype into the targeted field population. Endosymbiotic Wolbachia bacteria are potential transgene drivers, but infections do not naturally occur in some important mosquito vectors, notably Aedes aegypti. In this work, stable infections of wAlbB Wolbachia were established in A. aegypti and caused high rates of cytoplasmic incompatibility (that is, elimination of egg hatch). Laboratory cage tests demonstrated the ability of wAlbB to spread into an A. aegypti population after seeding of an uninfected population with infected females, reaching infection fixation within seven generations.     

Contrast Analysis of Mechanical Behavior of Confined Concrete with Stirrups and CFRP Under Axial Compression

Aiming at confined concrete with stirrups and carbon fiber reinforced plastic(CFRP) respectively, the major influence factors of mechanical behavior of confined concrete under axial compression were studied based on reported experimental data. The equations for calculating the peak stress, peak strain and ultimate strain were proposed respectively for confined concrete with stirrups and CFRP. Contrastive analysis shows that the behavior of confined concrete with stirrups is better than confined concrete with CFRP in low characteristic value, whereas the conclusion is contrary in high characteristic value.     

The effect of 5-aminoimidazole-4-carboxamide ribonucleoside （AICAR） on fatty acid oxidation in hepatocytes isolated from neonatal p~glets

In the present study, the effect of 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) on long-chain fatty acid oxidation by hepatocytes isolated from suckled neonatal pig liver (a low ketogenic and lipogenic tissue) was tested. Incubation of hepatocytes with AICAR (0.5 mM) in the presence of 1 mM of carnitine and 10 mM of glucose for 1 hour at 37°C had no significant effect on total [1-14C]-palmitate (0.5 mM) oxidation (14CO2 and 14C-Acid soluble products (ASP)). Consistent with the fatty acid oxidation, carnitine palmitoyltransferase I activity and inhibition of its activity by malonyl-CoA (10 μM) assayed in cell homogenate also remained constant. However, addition of AICAR to the hepatocytes decreased 14CO2 production by 18% compared to control (p < 0.06). The reduction of labeled carboxylic carbon accumulated in CO2 caused a significant difference in distribution of oxidative products between 14CO2 and 14C-ASP (p < 0.03) compared with the control. It was also noticed that acetyl-CoA carboxylase (ACC) was increased by AICAR (p < 0.03), indicating that ACC might drive acetyl-CoA toward fatty acid synthesis pathway and induce an increase in distribution of fatty acid carbon to 14C-ASP. Addition of insulin to hepatocyte incubations with AICAR did not change the oxidative product distribution between CO2 and ASP, but further promoted ACC activity. The increased ACC activity was 70% higher than in the control group when citrate was absent in the reaction medium and was 30% higher when citrate was present in the medium. Our results suggest that AICAR may affect the distribution of metabolic products from fatty acid oxidation by changing ACC activity in hepatocyte isolated from suckled neonatal piglets; however, the basis for the increase in ACC activity elicited by AICAR is not apparent.