The scope and scale of the informal food economy of South African urban residential townships: Results of a small-area micro-enterprise census

Growing urbanisation in South Africa is reflected in burgeoning Working class and informal township settlements on the fringes of its major towns and cities. Paired with this is an increasing reliance on cash as the primary means of economic transaction, which has in turn stimulated the growth of micro-enterprise business activities within the township context. This article discusses the findings of an eight-township small-area census which occurred between 2010 and 2013 in Cape Town, Johannesburg, Ekurhuleni and Durban townships representing 250 000 residents. The researchers were able to establish the scope and scale of informal food and drink retailing in these localities. Of the 10 049 micro-enterprises located in the study, some 3966 (or 39% of the total) trade in food. These include enterprises in primary production, fresh produce retailing, grocery retailing from house and spaza shops, and informal foodservice enterprises. Food is the basis for much township informal business and plays an important role in making food increasingly affordable and locally accessible, and in creating cash employment. The article builds on the knowledge base of the township informal economy role in bolstering food security needs for the marginalised.     

Some issues in blockchain for accounting and the supply chain,with an application of distributed databases to virtual organizations

This paper reviews some recent blockchain‐based applications for information capture, distribution and preservation. As part of that review, this paper examines two key concerns with current blockchain designs for accounting and supply chain transactions: data independence and multiple semantic models for the same information distribution problem. Blockchain applications typically integrate database, application and presentation tiers all in the same ledger. This results in a general inability to query information in the ledger and other concerns. Further, since most applications appear to be private blockchain applications, there is a concern of agents needing to accommodate multiple blockchains depending on who their trading partners are and what they request. Finally, this paper uses a distributed database to design a ‘blockchain‐like’ system for virtual organizations.     

Estimating yield curves of the U.S. Treasury securities: An interpolation approach

Following the approach of interpolation, this paper proposes the multiple exponential decay model to fit yield curves for both the U.S. TIPS market and the conventional Treasury security market. Several estimation methods, including the unconstrained/constrained nonlinear minimization, quadratic programming, and the iterative linear least squares, are applied to estimate the unknown parameters according to different curve‐fitting purposes. Comparisons between the proposed model and the alternatives show that the multiple exponential decay successfully (1) adapts to a variety of shapes associated with yield curves, (2) (partially) keeps in line with the economic interpretations of Nelson–Siegel summarized by Diebold and Li ( 2006 ), and (3) dominates the competing models in curve‐fitting performance measured by mean fitted‐price errors over the sample period. In addition, the exact specification of a nonparametric interpolation model is pinned down by applying three statistical tools, which enable us to jointly take into account validity, optimality, and parsimoniousness of the proposed model.     

可食性小麦蛋白膜的研究

本文介绍了小麦蛋白及其成膜特性,总结了国内外可食性蛋白膜的研究现状,提出了可食性小麦蛋白膜的研究方案,并对膜的安全性及其应用作了展望。     

现代网络安全技术分析

随着网络技术的广泛应用，网络安全也越来越受到重视。本简述了网络安全问题的定义和TCP／IP协议的安全漏洞。同时，介绍了当前网络采用的安全技术。     

银行保函在业主反索赔中重要作用的探讨

我国建筑业目前正处于加入WTO后的3～5年的过渡期，国内建筑市场国际化的趋势使工程索赔问题必须与国际惯例接轨，从国际工程惯例出发，详细论述了银行保函的种类及其在业主反索赔过程中的重要作用，为业主提供了一种可以借鉴的工程项目管理方式。     

我国外汇储备：安全性、成本风险及对策

我国外汇储备狭义上的安全性，即外汇储备资产本身的安全令人担忧。我国已经为高额的外汇储备付出巨大成本和承担了很高的风险，同时，高额外汇储备也对我国经济发展产生了一系列负面影响和风险。从这个意义上来看，我国外汇储备的现状已成为威胁金融安全的一个重要隐患。因此，我国外汇储备政策的调整已经刻不容缓。     

一种私钥管理实现技术

在对私钥管理技术深入研究的基础上，设计了一个私钥管理系统，并从系统的角度分析了私钥管理过程中所遇到的各种风险和最大程度地降低风险的方法。     

Awareness of Distributed Denial of Service Attacks' Dangers: Role of Internet Pricing Mechanisms

Denial of Service (DoS) attacks consist of overwhelming a server, a network or a Web site in order to paralyze its normal activity. The additional parameter in Distributed Denial of Service (DdoS) attacks is the distributing strategy. It means that DDoS attacks do not come from a single computer but stem from all accessible channels and servers. Consequences are multiple, ranging from system errors, temporary inability to access the Web site for normal users to challenging the actual reliability of the Internet. Despite this, Internet users show carelessness. The explanation lies in the specificities of DDoS attacks. We explore possibilities to raise users' awareness about the actual amplitude of problems caused by DDoS attacks. We suggest a careful examination of Internet pricing mechanisms and switching from flat to usage-constraining pricing schemes.     

China＇s Social Security： Case Studies of the Interest Groups and Policy Monopoly

This section introduces an asymmetric information model to analyze the interest groups and policy monopoly in social security management, mainly focusing on the relation between the interest groups in the social security products market and the social security government institutions at the central level, namely the major social security policy makers.