A geometric approach to portfolio optimization in models with transaction costs

We consider a continuous-time stochastic optimization problem with infinite horizon, linear dynamics, and cone constraints which includes as a particular case portfolio selection problems under transaction costs for models of stock and currency markets. Using an appropriate geometric formalism we show that the Bellman function is the unique viscosity solution of a HJB equation.Mathematics Subject Classification (1991): 60G44JEL Classification: G13, G11This research was done at Munich University of Technology supported by a Mercator Guest Professorship of the German Science Foundation (Deutsche Forschungsgemeinschaft). The authors also express their thanks to Mark Davis, Steve Shreve, and Michael Taksar for useful discussions concerning the principle of dynamic programming.     

Zur Qualität der Medienkontrolle: Ergebnisse einer Befragung deutscher Rundfunk- und Medienräte

This article presents the results of a survey among German media supervisors (members of supervising boards in public broadcasting stations and state media institutions). Given the increasing commercialization and internationalization of television, the supervising boards play a crucial part in assessing the quality of programs. From among 940 German supervisors, 364 took part in the survey, which covered the individual role conceptions of respondents as well as their attitudes towards quality criteria for television. Results suggest that both the supervisors’ amount of television use and the types of programs they prefer is clearly different from patterns in the population. This, along with the observation that supervisors often criticize what they saw privately, suggests (given the diversity of programs) that too much might be expected of them. Media supervisors do heed quality criteria in their work, but these probably do not correspond to other groups’ criteria, and especially not to the general population’s. To conclude, suggestions are discussed to improve the system of supervising programs by important social groups.     

The influence of the institutional context on corporate illegality

This paper examines the relationship between the institutional environment and sustained corporate illegality. We find that cognitive assumptions generate expectations that can, under specific circumstances, induce organizations to amplify illegal actions and that serve to lessen regulatory scrutiny. We also find that, once initiated, illegal actions can become hidden because of institutionalized practices that enable their concealment and that weaken the prospect of detection. These processes and effects are particularly noticeable in networks of professional regulators who become mutually over-confident and over-influenced by each other to the extent that their independent critical assessments and judgements are compromised. Mechanisms of mimetic herding and social humiliation compromise independence of judgement. Networks of interacting professionals are thus vulnerable to a collectively induced lowering of regulatory vigilance.     

Financing municipal BOOTs in South Africa: The lenders' perspective

South Africa's first build‐own‐operate‐transfer (BOOT) project for municipal services was signed in late December 1998 by the city of Durban and a private project company associated with French conglomerate Vivendi. The project will treat waste water for sale to industrial customers who would otherwise use more expensive potable water in their manufacturing processes. The project structure, with its multiple contracts and supporting agreements, guarantees and complex shareholding relationships, represents a sophisticated analytical challenge for lenders, whose financing will ultimately be at risk in the deal. Development finance institutions, such as the Development Bank of Southern Africa (DBSA), must review such projects in even greater detail because of their mandate to promote sustainable infrastructure development in the region. This article presents the DBSA ‘s analytical perspective on the Durban BOOT project in an effort to capture the complex, innovative and strongly developmental character of what, for South Africa, is a ground‐breaking public‐private partnership project.     

What do we one the future? the construction of a better present

The debt-to-the-future issue is discussed taking into account that it is not simply a poetic or innocent statement but a present complex problem. An analytical approach through the issue of risk and uncertainty might allow us to delimit our reflection. At the same time, it might become the main axis in the reality we face today, since risk, reliability, and uncertainty appear as characteristic features of modern society. Participatory processes, as manifestations of post-normal science, are proposed as a way to cope with uncertainty.     

Comparing system visions of farmers and experts

The goal of this paper is to identify farmers’ future in terms of the pesticide management of potato growing farmers in Vereda la Hoya (Boyacá, Colombia).To achieve this goal we applied the Future-Structured Mental Model Approach (Future-SMMA) and interviewed 10 farmers concerning their future perspectives and expectations to derive their future visions. Subsequently, 10 experts were interviewed about the feasibility and the consequences of farmers’ future visions.Applying the Future-SMMA, we analyzed farmers’ future visions and found that farmers take account of social and environmental threats and that their visions are optimistic. In addition we compared farmers’ and experts’ perceptions of external constraints on farmers’ future and discovered that the future visions of farmers and experts were inconsistent. Finally, we determined how farmers’ livelihood assets and self-perception influence the formation of farmers’ future visions and found that the more a person was able to differentiate his livelihood assets the more differentiated were the future visions of that person.In discussing our findings, we deduce that the inconsistency of future visions found is due to diverging attitudes towards future scenarios and differing opinions about who should take responsibility for the knowledge management of farmers.     

Gender disparities: a medical detoxification program

Significant gaps exist in health care regarding gender in the United States. Health status, social roles, culturally patterned behavior and access to health care can be influenced by gender. Women have been the primary users of health care and minority women usually have received poorer quality care than Non-Hispanic White (NHW) females. The objectives of this study were to identify gender, racial and ethnic disparities in access to substance abuse treatment in a Texas hospital. Secondary data collected on 1,309 subjects who underwent detoxification were studied. Gender, race/ethnicity, drug of abuse, relapse and financial classification were included in the analysis. Results indicate Hispanic females and Non-Hispanic Black (NHB) females were about 5 and 3.5 more likely than NHW females to use Medicaid services respectively (p < .05). NHW and NHB males were more likely to use Medicare than females (p < .05). NHB and Hispanic females were 5.8 and 2.1 times more likely to receive care for abuse of cocaine when compared to NHW females respectively (p < .05). Hispanic females were 2.3 times more likely to relapse than Non-Hispanic females, and uninsured NHB females were 7.1 times at a higher risk to abuse multiple drugs compare to NHW females (p < .05). Socio-economic factors, lower labor force participation rates, and less financial independence can explain females utilizing more often Medicaid regardless of their race/ethnicity. These results can be also explained by aggressive case management utilization, socio cultural barriers and/or discriminatory practices, both intentional and unintentional.