P2P文件共享网络中被动蠕虫传播建模与分析

为了抑制P2P被动型蠕虫在大规模P2P文件共享网中的传播和攻击,对P2P网络中文件共享的特点和被动型蠕虫传播的特点进行了深入的分析,并在此基础上提出了3个分别适用于蠕虫传播不同阶段的传播模型。为了证明模型的正确性,进行了大规模仿真实验。使用专门的数值分析工具求出相应模型的理论值。为了仿真大规模P2P文件共享网,专门基于P2P仿真平台开发出能真实模拟流行P2P文件共享网的软件并基于该软件进行了仿真。理论值与仿真值匹配的事实表明,该模型基本上反映了蠕虫的传播情况,可以用来预测蠕虫的传播趋势和行为。     

Relationships between endogenous polyamines, cellular structure and arrested growth of grape berries

The condition known as 'millerandage' occurs when the growth of grape berries is interrupted early in their development. By harvest, berries in the same bunch will be different sizes, and some will be particularly small. Anatomical studies have revealed that interrupted growth can occur at different stages of berry development, and hormonal factors might be involved. Polyamines are one class of hormones that play an important role in plant morphogenesis, but analysis of polyamine content and composition indicated that berries of bunches with millerandage had the same polyamine composition as those at different stages of development. However, there were differences in relationships between wall-bound polyamine, especially wall-bound DAP, and arrested growth of berries. One key cytological difference was the negative PAS staining of cell walls in very small and in mid-size berries. In biochemical terms, wall-bound polyamine (and in particular wall-bound DAP content), was higher in berries from bunches with millerandage than in normal berries during their development. The present study therefore clearly demonstrates a positive correlation between wall-bound polyamine, especially wall-bound DAP, and arrested growth of berries in bunches with millerandage.     

“SCENOGRAPHIC” AND “COSMETIC” PLANNING: GLOBALIZATION AND TERRITORIAL RESTRUCTURING IN BUENOS AIRES

ABSTRACT: The aim of the present article is to provide an account of the ways in which the impact exerted by globalizing forces on the territorial structure of the city of Buenos Aires has been mediated by local planning processes. After a brief review of the main trends and critiques found in the academic literature, the author examines how the territorial transformations that have taken place in Buenos Aires over the past fifteen years may not be simplistically related to—or blamed on—global pressures. It is argued that the determinacy imposed by long‐term historical tendencies, together with specific territorial planning arrangements characteristic of the Argentine planning system, have played a major role in the production of Buenos Aires' territorial structuring over the past fifteen years.     

CAPACITY OF ACTIVATED SLUDGE SOLIDS FOR VIRUS ADSORPTION

The first significant reduction in wastewater virus concentration occurs in the biological treatment process, either by removal of solid matter in which virus is embedded or by adsorption of virus to the biomass. In addition, the effectiveness of subsequent disinfection and the ultimate fate of treatment plant effluent virus are dependent on the extent of virus association with small suspended particles. This report is a study of adsorption of Type I poliovirus to solids collected from an activated sludge unit and resuspended in filtered final effluent. Virus adsorption capacity was correlated by an isotherm relationship which includes the effect of decreasing capacity with increasing solids concentration. This effect is probably caused by decreased solids surface area due to solids aggregation. The results indicate smaller capacity at typical activated sludge mixed liquor solids concentration than would be predicted from previous studies, and that only about 20% of total virus are adsorbed at low solids concentration typical for treatment plant effluent.     

Contradictions and Complexities

When Robert Venturi began writing Complexity and Contradiction in Architecture in 1962, Jane Jacobs's The Death and Life of Great American Cities (1961) was the subject of dinner-table conversation across the country. Apart from Jacobs's direct influence, among the parallels that emerged from their Townscape affiliations and other interests, the concept of complexity stands out, with Venturi's conception echoing Jacobs's historic introduction of complexity science into architectural and urban theory. While Venturi did not seek to extend the scientific research put forward by Jacobs, favoring instead the complexities suggested by gestalt theory and New Criticism, he cited similar scientific sources and derived similar principles for urbanism, as revealed by his Copley Square project of 1966.