Preventing HIV in injection drug users: exploring the tradeoffs between interventions

Injection drug users (IDUs) transmit the human immunodeficiency virus (HIV) via both needle sharing and sex. Available interventions for this population have varying costs and effectiveness and focus on different risk behaviors. In this analysis, we look at two interventions. One is inexpensive, broad-based and provides modest risk reductions (street outreach (SO)); the other is narrowly focused, expensive and relatively effective (methadone maintenance). This analysis explores the effects of population risk behavior, intervention effectiveness, intervention costs, and decision constraints when allocating funds between these two interventions to maximize effectiveness. We develop a model of the spread of HIV, dividing IDUs into susceptibles (uninfected) and infectives, and separately portraying sex and injection risk. We simulate the epidemic in New York City for time periods from the mid-1980s to the early 1990s, and incorporate the behavioral effects of two interventions performed singly or in combination to find the allocation that maximizes the number of infections averted in the IDUs and their noninjecting sex partners, assuming interventions have increasing marginal costs. We find that the optimal allocation nearly always involves spending the maximum allowable amount on SO. This result is largely insensitive to variations in risk parameters, intervention efficacy, or cost. The model's structure, however, makes clear that many factors contribute to this insensitivity, namely the scope of the interventions, the dual drug/sex nature of HIV risk in the population, the asymmetry of sexual risk for men and women, and the potential benefits to nonIDUs.     

EVOLUTION AND REVOLUTION: A QUANTUM VIEW OF STRUCTURAL CHANGE IN ORGANIZATIONS

There may be hidden costs in making prompt incremental and piecemeal changes to organizational structure to cope with a new strategy or environment. We shall argue that changeless stable intervals punctuated by infrequent but revolutionary periods of ‘quantum’or multifaceted structural change may sometimes be the most economical strategy. Incremental structural changes may create severe and costly disharmonies as they destroy an integral structural configuration. These costs might outweigh the benefits of adapting structure to changes in strategy and environment. Because such costs may be high it might be necessary to delay changing until they can be justified. Such delays can require subsequent revolutionary structural changes. The applicability of this view of change for different contexts will be discussed.     

基于PLC的路灯控制系统设计

基于PLC控制的路灯控制系统在灯具节能上把握了节能的新方向,采用节流降功率,克服了隔灯点亮的光照不均匀性和降压节能的灯具寿命缩短、不能点亮等问题。该系统具有运行可靠、可操作行强、可连续扩展、节能效果明显、成本和维护费用低等优点,可通过编程来改变控制方案,适用于有不同时差的地区,是路灯节能的发展趋势。     

Employers' hiring practices,employment protection,and costly search: A vacancy-level analysis

An employer with a vacancy may respond to high search costs by lowering hiring requirements. While such an adjustment increases the employer's chances of filling the vacancy, it also more likely results in a match that terminates when the match is hit by match-specific productivity shocks. Drawing on a novel Slovenian vacancy dataset, we find that employers who are searching to fill temporary positions are more likely to hire underqualified workers when search costs are high. We find that search costs are taken into consideration when employers are searching to fill permanent positions in some specifications but not all. These findings suggest that for employers who are searching to fill a permanent position, the benefits of lowering hiring requirements when search costs are high are likely outweighed by: a) high firing costs if an under-qualified worker is hired on a permanent contract or b) the costs of undertaking a new search later if an under-qualified worker is hired on a temporary contract. These are novel findings about the employers' hiring practices in the presence of employment protection laws and costly search.     

Changing the colour of night on urban streets - LED vs. part-night lighting system

Many cities in the United Kingdom are upgrading the streetlights to white light-emitting diode (LED) lamps for reducing the electricity costs and attaining the sustainable energy solutions. Installation of LED lamps on urban street requires higher installation costs and a long-term period to payback benefits of replacing outdated streetlights in terms of energy savings and costs. To achieve the short-term energy efficiency of urban street lighting, city councils sometimes adopt the part-night lighting system particularly in the residential areas. The Coventry City Council recently replaced 29,701 existing sodium lights with LED lamps. This paper performs the economic analyses to understand the feasibility of two street lighting systems: LED lamps and ‘part-night’ lightings on the Coventry streets during the twenty-year period assuming the return period of investment is twenty years. The projection of energy consumption and costs for LED lamps and part-night lighting systems shows that electricity can be saved by 44% and 21% comparing to current electricity usages, respectively. Considering the budgetary constraints of Coventry City Council, this paper concludes that the part-night lighting system may be beneficial in short-term period, but it is economically feasible to replace the existing lower efficiency lights with LED lamps.     

The shared environmental responsibility principle: new developments applied to the case of marine ecosystems

Estuaries provide advantageous sites for both harbors and fish habitats. In many countries, harbor expansion in estuaries contributed to the decline of fish populations with impacts at the global scale. Restoring these habitats is important to prevent a global biodiversity crisis but is costly and potentially unaffordable for polluters under the Polluter Pays Principle. Such affordability issues prompt decision-makers to reduce environmental targets of restoration programs. Harbor infrastructures destroy fish habitats but generate benefits for society and contribute to the public interest, raising some questions on who is responsible for environmental degradations and who can afford environmental restoration costs? One way to allocate restoration costs is to analyze the amount of harbor services consumed by economic sectors. This paper addresses these questions by computing burden sharing scenarios with an input–output matrix. These scenarios are simulated under the shared responsibility principle to distribute restoration costs among stakeholders in the Seine estuary, France.     

The Effectiveness of Educational and Needle Exchange Programs: A Meta-analysis of HIV Prevention Strategies for Injecting Drug Users

A meta-analysis of 16 educational interventions and 10 needle exchange programs was performed to estimate the effectiveness of reducing HIV risk behaviors in the injecting drug user population. Information on intervention, outcome, design and demographics was coded and analyzed for all educational and needle exchange program evaluation studies published between January 1984 and May 1995. The weighted mean effect size for the 6,251 study subjects of the 16 educational interventions was 0.749 (95% CI, 0.708 to 0.790), and the weighted mean effect size for the 1,675 study subjects of the 10 needle exchange programs was 0.279 (95% CI, 0.207 to 0.352), suggesting that both interventions had a positive impact on reducing HIV risk behaviors associated with injecting drug use. However, these results were dependent upon research design, outcome type and follow-up time.     

Oligopolies with (Somewhat) Environmentally Conscious Consumers: Market Equilibrium and Regulatory Intervention

We consider a horizontally differentiated duopoly where consumers care about the product's “greenness.” Firms can be asymmetric: they may differ in the product's intrinsic value and may also differ in their chosen level of greenness. We examine the choice of greenness and the implications of various policy interventions. We show that (i) the choices of product greenness are strategic substitutes, (ii) the high‐intrinsic quality firm produces the greener product, (iii) the low‐quality firm's greenness may increase with the cost of its provision or decrease with consumer willingness to pay for it, (iv) a minimum quality standard (MQS) leads the greener firm to lower its environmental quality and can even reduce average quality, (v) greenness is underprovided even if consumers fully internalize the externality, and (v) an MQS can reduce welfare if the greenness of the high‐quality firm exceeds the MQS, even when environmental quality is underprovided. The effects of policy interventions on profits differ qualitatively across polices and firms: A firm that lobbies for one type of intervention may lobby against another similar one, and a firm may lobby for an intervention while its competitor may lobby against it. A subsidy for the development costs of a green product can financially hurt both firms.     

High-risk clients and mental health care management.

A framework characterizing high-risk psychiatric patients by their probability of hospitalization and lengthy stay is introduced. Risk curves are then developed for each patient showing the potential impact of mental health case management on patient risk. Preliminary empirical analysis reveals that although most patients benefit from the case management intervention, some 30% of the client population may face an increase in risk of hospitalization and lengthy stay.     

Estimating the benefits of effectively and proactively maintaining infrastructure with the innovative Smart Infrastructure sensor system

An innovative sensor system, designated ‘Smart Infrastructure,’ is being developed jointly by Cambridge University in the United Kingdom and Massachusetts Institute of Technology in the United States. This system provides real-time wireless information about the state of critical infrastructure. The Smart Infrastructure sensors are designed to monitor infrastructure, such as water pipelines, as well as to increase their capabilities for purposes of efficient maintenance. This paper presents a forecasting model that assesses the possible impacts of Smart Infrastructure technology currently being applied to the British water pipe market. In doing so, we identify key benefits of proactively managing infrastructure with such new technology. A probabilistic cost benefit analysis, which takes into account future uncertainty, is conducted using a Monte Carlo simulation. Our findings suggest that if the Smart Infrastructure sensor system is applied to water pipelines in the British market, there are likely to be significant economic benefits. They could be realised by avoiding disruption and damage costs (including water loss) due to water pipe bursts, as well as by reducing annual operating and maintenance costs. The mean cumulative net present value of savings derived from the case scenario for the period through year 2056 was estimated at US$ 23.7 billion.     

PRICE-LEVEL TARGETING AND STABILISATION POLICY: A SURVEY

Abstract.  This paper surveys recent articles on the costs and benefits of price-level targeting, focusing its use as a tool for stabilisation policy. It discusses how price-level targeting can affect the short-run trade-off between output and inflation variability by influencing inflation expectations. It reviews how assigning an explicit price-level target to a central bank that is unable to commit to its future policies can improve economic performance. It surveys other potential benefits and costs. Among the costs, it underlines the importance of perfectly rational expectations for the optimality of price-level targeting, and an exacerbation of the time inconsistency problem.     

The Social Costs of Innovation Policy

Innovation policy is designed to produce social benefits by solving a market failure problem associated with private investment in new knowledge. Yet the social costs of these policy interventions are routinely ignored. We use the Djankov et al. (2003) institutional possibility frontier model to analyse the trade‐offs between the social costs of disorder and those of dictatorship that particular innovation policies impose. We show how different innovation policies impose different types of social costs. We conclude that the case for public support for innovation policies is often both distorted and overstated because of failure to account for social costs.     

The Effects of Empowerment on Attitudes and Performance: The Role of Social Support and Empowerment Beliefs

abstract    This paper reports the results of a randomized field experiment that tested the effects of an empowerment intervention among unit managers of a large trucking company. The intervention was designed to increase participants' beliefs in their personal control and self-efficacy with regard to key aspects of their jobs. Individuals who managed geographically dispersed profit centres were randomly assigned to either an intervention group (N = 38) or a no-treatment control group (N = 30). The intervention significantly increased perceptions of maintenance control and impact at four months after the intervention, but only for those managers who felt that their supervisors were supportive. The intervention also improved archival measures of unit performance and affected work attitudes (depending upon the level of perceived supervisory support). The data point out the key role that perceived supervisor social support plays when implementing such organizational change interventions.     

Tax expenditures and other programs to stimulate housing: Do we need more?

Discussions to aid the housing industry raise several questions. First, does stimulation of housing demand require new direct subsidy programs? And, second, are any programs to increase demand worth their costs to society? The results in this paper indicate that the answer to both questions is no: the existing subsidy to homeownership in the tax code is, when combined with mortgage instruments that offset cash flow problems, fully capable of generating large increases in demand at the cost of significant tax expenditures; and the social benefits of increased housing demand are shown to be worth only about 60% of their costs. Consequently, increasing housing demand can be readily achieved, but doing so will be costly to the government and inefficient for society.     

Primary prevention and health outcomes: Treatment of residential lead-based paint hazards and the prevalence of childhood lead poisoning

In order to gain a better understanding of the effects of an investment in primary prevention on health, I investigate the impact of treatment of lead-based paint hazards in housing units (the preventive action) on childhood lead poisoning (the health outcome) at the census tract level in Chicago, IL. I use the findings from the analysis to simulate and then weigh the costs of lead interventions against the potential benefits of reducing blood lead levels in children. Childhood lead poisoning presents an interesting case study of the potential of preventive care in reducing the prevalence of a disease. There is a clear, well-defined pathway of exposure (deteriorating lead paint in older homes) and no method of secondary care that effectively mitigates the negative health effects. I find that a one-tenth percentage point increase in the proportion of older housing units that have been remediated is associated with a four-tenths percentage point reduction in the prevalence of childhood lead poisoning, an elasticity of roughly 0.5. Citywide, this is roughly 2.5 cases of lead poisoning averted for every housing unit remediated. Furthermore, I find evidence that the effect of remediations in preventing the disease has improved over time. The lower bound estimates of the benefits associated with the reduction in lead poisoning - increased expected lifetime earnings and reduced medical expenditures - are two to twenty times the estimated costs of the remediations.     

The holdout problem and urban sprawl: Experimental evidence

Conventional wisdom as well as economic theory suggests it is more costly to reassemble fragmented land due to transactions costs and strategic bargaining costs. Both costs are expected to increase with the number of sellers. Inefficient allocation of land resources may result including property entropy (Parisi, 2002), urban sprawl (Miceli and Sirmans, 2007) and deteriorating inner cities. Given the difficulty of observing actual values attached by buyers and sellers to land, little empirical evidence exists to support the conventional wisdom and theoretical work. We use experimental methods to examine transactions costs and strategic bargaining costs in a land-assembly market game with one buyer, 1-4 sellers, and complementary exchanges. The buyer’s final earnings vary inversely with the number of sellers, ceteris paribus, indicating an incentive to purchase consolidated land. Delay costs reduce holdout, but result in lower payoffs for both buyers and sellers. Competition between sellers reduces holdout and the buyer’s total purchase price.     

Urban search models under high-relocation costs. Theory and application to spatial mismatch

We develop a search-matching model in which mobility costs are so high that it is too costly for workers to relocate when a change in their employment status occurs. We show that, in equilibrium, wages increase with distance to jobs and commuting costs because firms need to compensate the transportation cost difference between the employed and unemployed workers at each location in the city. We also show that the equilibrium land rent is negatively affected by the unemployment benefit because an increase in the latter induce firms to create less jobs, which, in turn, reduces the competition in the land market. We then use this model to provide a mechanism for the observed spatial mismatch between where black workers live and where jobs are. We finally show that a transportation policy consisting in subsidizing the commuting costs of black workers can increase job creation and reduce unemployment if the level of the subsidy is set at a sufficiently high level.     

The effects of high-speed rail on accessibility and equity: Evidence from the Turin-Lyon case-study

According to EU directives, cost-benefit analysis (CBA) is adopted to assess the impacts of high-speed rail (HSR). CBA evaluates the effectiveness of such infrastructure, determining whether and to what extent the present benefits overcome the present opportunity costs. However, it fails to include equity issues, which are the key aspects of transport planning. After a general discussion of equity in HSR and its link with the concept of accessibility, this study describes some complementary methods to calculate the variation in equity. Four of them (i.e. the potential accessibility index, spatial rail equity index, Gini index, and coefficient of variation) were adopted to assess the equity impacts for the Italian municipalities along the Turin-Lyon HSR. The results of the analysis reveal that despite a generalised increase in overall accessibility, equity implications are more contradictory, with main localities gaining further benefits compared to medium- and small-sized municipalities. In particular, the latter register a further increase in peripheralization. However, since they account for 36% of the total surface but represent only approximately 1% of the total population, the overall balance for the population served by the infrastructure may be considered positive. These results are particularly useful in contexts where the acceptance of HSR is weak, as they allow policymakers to identify adequate compensation measures to reduce the gap and increase territorial cohesion.     

城市街道家具的生态设计

街道家具的设计是城市规划和设计的深化和细化,街道家具生态设计是一种新的设计理念。论述了街道家具生态设计的特点及意义,分析了街道家具生态设计的主要内容。指出生态街道家具实现了社会效益、经济效益、环境效益三者的统一。     

Equilibrium price and advertisement distributions

We consider an economy where many sellers sell identical goods to many buyers. Each seller has a unit supply and each buyer has a unit demand. The only possible information flow about prices is through costly advertising. We show that in equilibrium the sellers use mixed strategies in pricing which leads to price and advertisement distributions. With convex advertising costs each seller sends only one advertisement in the market. We also delineate a class of advertising costs which ensures that sellers may send multiple advertisements in equilibrium. Higher prices are advertised more than lower prices.