THE BURDEN OF HIV/AIDS IN THE PUBLIC HEALTHCARE SYSTEM

Given current lack of routine data, assessing the burden of HIV/AIDS on the public healthcare system is complex. This research aimed to collect a wide range of data that could be used to estimate this burden and the costs of meeting it. Data collection was undertaken by research doctors who were employed in a wide spectrum of facilities to compile information on patients' HIV-status, retrospective utilisation of services and unit costs of care. Key results indicated that the percentage of expenditure on HIV-related care was 26% across all facilities. HIV-positive patients had higher utilisation of services compared to other patient groups; the annual cost per patient was estimated to be R4,813 (2007/08 prices). Results should be interpreted in the light of the underlying population need and context-specific access barriers.     

Electronic Finance: Reshaping the Financial Landscape Around the World

In recent years, the emergence of electronic finance—especially online banking and brokerage services, and new trading systems—has reshaped the financial landscape around the world. This paper reviews these developments and finds that they are greatly impacting the structure of and competition in financial services industries and will have a large impact on incumbents. Its assessment of how e-finance, and globalization more generally, affects countries highlights the need for changes in four financial sector policy areas—safety and soundness, competition policy, consumer and investor protection, and global public policies—to mitigate risks and reap as much as possible the potential benefits of e-finance.     

How far can reduced childcare prices push female labour supply?

Exploiting exogenous variation in childcare prices stemming from a childcare price reform, this paper estimates effects of reductions in childcare costs on female labour supply. The reform introduced a cap on childcare prices, and lead to considerable reductions in prices depending on family type and region of residence. Since the price is determined by a handful of observed characteristics, we are able to match households that are similar in all relevant aspects, but experienced quite different price changes. Our difference-in-differences regression matching estimates are very precise, and close to zero.     

ARBITRAGE IN SECURITIES MARKETS WITH SHORT-SALES CONSTRAINTS

In this paper we derive the implications of the absence of arbitrage in securities markets models where traded securities are subject to short-sales constraints and where the borrowing and lending rates differ. We show that a securities price system is arbitrage free if and only if there exists a numeraire and an equivalent probability measure for which the normalized (by the numeraire) price processes of traded securities are supermartingales. Also, the tightest arbitrage bounds that can be inferred on the price of a contingent claim without knowing agents'preferences are equal to its largest and smallest expected normalized payoff with respect to the supermartingale measures. In the case where the underlying security price follows a diffusion process and where short selling is possible but costly, we derive partial differential equations that must be satisfied by the arbitrage bounds on derivative securities prices, and we determine optimal hedging strategies. We compute the arbitrage bounds on common securities numerically for several values of the borrowing and short-selling costs and show that they can be quite sharp.     

基于网络技术的建筑企业信息化管理探讨

从应用网络技术的角度出发，对网络信息技术在建筑企业多个项目管理中的应用——特别是建筑企业的管理机关、职能部门和工程现场的信息化管理进行了初步的探讨。对实现工程项目网络化管理的几种方式的工作原理、可行性以及优缺点进行了比较分析，其中重点介绍了适合目前国内建筑工程现场办公条件的B/S网络结构原理及其应用的可行性。     

Disposition effect and analyst forecast dispersion

Behavioral finance theories posit that behavioral biases are more pronounced when there is higher information uncertainty about fundamentals. This paper examines the relation between the disposition effect, the tendency to ride losses and realize gains, and dispersion in financial analysts’ earnings forecasts for a sample of large U.S. discount brokerage accounts from January 1991 to December 1996. I find that the disposition effect is exacerbated in stocks with higher analyst forecast dispersion. In particular, the disposition effect is 10% in stocks in the highest forecast dispersion quintile and not significant in the lowest forecast dispersion quintile. The driving factor behind these findings is investors’ higher propensity to realize gains when facing higher information uncertainty. The results are robust to controlling for firm size, analyst coverage, idiosyncratic volatility, turnover, and past market-adjusted returns. The results provide supportive evidence for a behavioral bias explanation of the disposition effect consistent with mean-reversion beliefs for winners and loss actualization avoidance for losers.     

Mixed Causal–Noncausal Autoregressions: Bimodality Issues in Estimation and Unit Root Testing1

This paper stresses the bimodality of the likelihood function of the Mixed causal–noncausal AutoRegressions (MAR), and it is shown that the bimodality issue becomes more salient as the causal root approaches unity from below. The consequences are important as the roots of the local maxima are typically interchanged, attributing the noncausal component to the causal one and vice‐versa. This severely changes the interpretation of the results, and the properties of unit root tests of the backward root are adversely affected. To circumvent the bimodality issue, this paper proposes an estimation strategy which (i) increases noticeably the probability of attaining the global MLE; and (ii) selects carefully the maximum used for the unit root test against a MAR stationary alternative.     

The multiplex structure of interbank networks

The interbank market has a natural multiplex network representation. We employ a unique database of supervisory reports on Italian banks to the Banca d’Italia that includes all bilateral exposures broken down by maturity and by the secured and unsecured nature of the contract. We find that layers have different topological properties and persistence over time. The presence of a link in a layer is not a good predictor of the presence of the same link in other layers. Maximum entropy models reveal different unexpected substructures, such as network motifs, in different layers. Using the total interbank network or focusing on a specific layer as representative of the other layers provides a poor representation of interlinkages in the interbank market and could lead to biased estimation of systemic risk.