两种预投射分支的差异

刻划了两种预投射分支的本质差异 ,并给出了一个反例 ,说明这两种分支是不同的     

弹性地基上方形构件的风致振动分析

研究了弹性地基上方形构件在横向空气动力作用下的振动现象．分别采用七次及三次多项式对实测的空气动力进行拟合．利用平均化方法分析了物体的极限环运动规律，以及典型的分叉、跳跃、滞后等非线性现象     

一类生化反应模型极限环的存在唯一性

摘要：用定性的方法讨论了一类生化反应模型，dx/dt=ζ-xy^4,dy/dt=xy^4-by，并证明了其极限环的存在性，不存在性及极限环的存在唯一性，得到了完整的结果。     

图的因子控制

P．Dnkdmann和R．C．Laskar(2003年)提出如下猜想：设F1和F2是完全图Kn的两个边不交的因子，如果δ(Ei)≥2，i=1，2，则因子控制数γ(F1，F2)≤3n/5。如果F1UF2有长的交错路，则猜想成立。     

关于一类Ramsey数的下界

对一类图K1 ,q2 t与C4的Ramsey数进行讨论 ,得出结论 :r(C4,K1 ,q2 t) q2 q 2 .并且对Burr的渐近下界做了改进 ,得到改进结论 : n 4 ,f(n) ( 7n -5 ) 6 .     

一类植物——食植者系统的定性分析

本文研究了一类植物——食植者系统,得到当d_1=d_2时.正平衡点的全局稳定性和极限环存在唯一性的充分条件.     

Identifying US business cycle regimes using dynamic factors and neural network models

We use dynamic factors and neural network models to identify current and past states (instead of future) of the US business cycle. In the first step, we reduce noise in data by using a moving average filter. Dynamic factors are then extracted from a large-scale data set consisted of more than 100 variables. In the last step, these dynamic factors are fed into the neural network model for predicting business cycle regimes. We show that our proposed method follows US business cycle regimes quite accurately in-sample and out-of-sample without taking account of the historical data availability. Our results also indicate that noise reduction is an important step for business cycle prediction. Furthermore, using pseudo real time and vintage data, we show that our neural network model identifies turning points quite accurately and very quickly in real time.     

Biological characterization of the obligate symbiosis between Acropyga sauteri Forel (Hymenoptera: Formicidae) and Eumyrmococcus smithii Silvestri (Hemiptera: Pseudococcidae: Rhizoecinae) on Okinawa Island,southern Japan

The ant Acropyga sauteri Forel has an obligate, mutualistic symbiosis with a mealybug, Eumyrmococcus smithii Silvestri, on Okinawa Island, southern Japan. The mealybugs live inside ant nests nearly all their lives, and the ants depend on them for food. Alate foundress queens carry mealybugs during their nuptial flights, using them to establish new colonies at new sites. However, important aspects of the symbiosis have not yet been elucidated. The present study characterizes the basic biology of the symbiosis and describes for the first time the morphologies of all growth stages of E. smithii. Our study suggests that E. smithii has only one nymphal stage, followed by a female pupal stage or male prepupal stage. Intensive sampling of ant nests across seasons showed that A. sauteri prefers nest sites 5–20 cm underground. Acropyga sauteri produced reproductive stages mainly in mid‐March or early April, and numbers of both ant workers and mealybugs increased from spring to summer. Experimental determination of colony identity with a method using nestmate recognition by ants suggested that each ant colony rarely has a perimeter greater than 30 cm, that the ants are monogynous, and that different ant colonies are densely aggregated along the root system of a plant, adjacent to each other but not interflowing. Both symbiotic partners were vulnerable to attacks by several common subaerial ant species following physical disturbance to their nests.     

Nitric oxide biosynthesis, nitric oxide synthase inhibitors and arginase competition for L-arginine utilization

Nitric oxide (NO) is a recently discovered mediator produced by mammalian cells. It plays a key role in neurotransmission, control of blood pressure, and cellular defense mechanisms. Nitric oxide synthases (NOSs) catalyze the oxidation of L-arginine to NO and L-citrulline. NOSs are unique enzymes in that they possess on the same polypeptidic chain a reductase domain and an oxygenase domain closely related to cytochrome P450s. NO and superoxide formation as well as NOS stability are finely regulated by Ca²⁺/calmodulin interactions, by the cofactor tetrahydrobiopterin, and by substrate availability. Strong interactions between the L-arginine-metabolizing enzymes are clearly demonstrated by competition between NOSs and arginases for L-arginine utilization, and by potent inhibition of arginase activity by N^ω-hydroxy-L-arginine, an intermediate in the L-arginine to NO pathway.