Market Entry and Foreign Direct Investment

This paper discusses the impact of foreign direct investment (FDI) on market entry and welfare. It assumes that firms may enter markets in the first period as national firms only. In the second period, however, FDI is possible. The paper demonstrates that FDI reduces market entry because equilibrium profits in the second period decline with a decrease in the fixed cost of FDI. Therefore, compared to a trade regime without any FDI, prices rise in the first period but decline in the second period. The paper shows, however, that FDI will unambiguously improve the discounted sum of consumer surplus.foreign direct investment, multinational enterprises, imperfect competition, free entry

Effort levels in contests: an empirical application of the Tullock model

Empirical applications of the Tullock contest model are rare, due in part to the non-observability of effort. This paper presents an application of the standard Tullock model in a setting where effort can be observed and explained. A simple contest model is used to predict levels of effort in English soccer, with data on fouls and yellow and red cards used to reflect the effort of teams. Effort levels are found to be higher in matches between evenly balanced teams, and in matches with implications for end-of-season outcomes. The results suggest that the teams’ effort levels are strategic complements.Tullock contest, team sport, strategic complements.

Endogenous Market Structures and the Gains from Foreign Direct Investment

This paper discusses the gains from liberalizing foreign direct investment (FDI) in a two country setting with endogenous market structures. Two different scenarios are investigated. In the first scenario, headquarters are run in the domestic country only and the FDI regime is compared to the intersectoral trade case. If multinational and national firms coexist, market concentration occurs and FDI is welfare improving for the foreign country, but welfare declining for the domestic country. In the second scenario, headquarters are run in both countries and the FDI regime is compared to the intraindustry trade case. This regime switch leads to mutual welfare gains, irrespective of market structure effects.

Economic and legal aspects of international environmental agreements: The case of enforcing and stabilising an international CO 2 agreement

The protection of the global environment is impeded by multilateral externalities which the international community attempts to bring under control by entering into international agreements. International agreements, however, can suffer from non-compliance and free-riding behaviour by sovereign states and must therefore be enforced and stabilised internationally. This paper describes instruments for the enforcement and stabilisation of an international CO2 agreement and evaluates them in the light of economic and legal theory. Economic instruments build on repetition and use utility transfers, economic sanctions and flexible treaty adjustments. Important legal instruments are reciprocal obligations and cooperation duties, international funding and transfer rules, treaty suspension, retorsions and reprisals, treaty revision, and monitoring. The paper shows that economic and legal instruments are compatible to a considerable extent. It develops proposals for the enforcement and stabilisation of a global CO2 agreement and other multilateral treaties.International environmental agreements,international cooperation,non-compliance,enforcement,global warming,international law

Trapped Protostellar Winds and their Breakout

Observations show that high-velocity jets stem from deeply embedded young stars, which may still be experiencing infall from their parent cloud cores. Yet theory predicts that, early in this buildup, any outgoing wind is trapped by incoming material of low angular momentum. As collapse continues and brings in more rapidly rotating gas, the wind can eventually break out. Here we model this transition by following the motion of the shocked shell created by impact of the wind and a rotating, collapsing envelope. We first demonstrate, both analytically and numerically, that our previous, quasi-static solutions are dynamically unstable. Our present, fully time-dependent calculations include cases both where the wind is driven back by infall to the stellar surface, and where it erupts as a true outflow. For the latter, we find that the time of breakout is sim 50,000 yr for wind speeds of 200 km/s. The reason for the delay is that the shocked material, including the swept-up infall, must be able to climb out of the star's gravitational potential well. We explore the critical wind speed necessary for breakout as a function of the mass transport rates in the wind and infall, as well as the cloud rotation rate Omega0 and time since the start of infall. Breakout does occur for realistic parameter choices. The actual breakout times would change if we relaxed the assumption of perfect mixing between the wind and infall material. Our expanding shells do not exhibit the collimation of observed jets, but continue to expand laterally. To halt this expansion, the density in the envelope must fall off less steeply than in our model.Comment: 44 pages, 10 figures, accepted to Ap

Accretion disks around massive stars: Hydrodynamic structure, stability and dust sublimation

We investigate the structure of accretion disks around massive protostar applying steady state models of thin disks. The thin disk equations are solved with proper opacities for dust and gas taking into account the huge temperature variation along the disk. We explore a wide parameter range concerning stellar mass, accretion rate, and viscosity parameter \alpha . The most essential finding is a very high temperature of the inner disk. For e.g. a 10 M_sun protostar and an accretion rate of 10^-4 M_sun/yr, the disk midplane temperature may reach almost 10^5 K. The disk luminosity in this case is about 10^4 L_sun and, thus, potentially higher than that of a massive protostar. We motivate our disk model with similarly hot disks around compact stars. We calculate a dust sublimation radius by turbulent disk self-heating of more than 10AU, a radius, which is 3 times larger than caused by stellar irradiation. We discuss implications of this result on the flashlight effect and the consequences for the radiation pressure of the central star. In difference to disks around low mass protostars our models suggest rather high values for the disk turbulence parameter \alpha close to unity. However, disk stability to fragmentation due to thermal effects and gravitational instability would require a lower \alpha value. For \alpha = 0.1 we find stable disks out to 80AU. Essentially, our model allows to compare the outer disk to some of the observed massive protostellar disk sources, and from that, extrapolate on the disk structure close to the star which is yet impossible to observe.Comment: 23 pages, 8 figures, accepted by ApJ, For full version see http://www.mpia.de/homes/vaidya

Analytic solutions to the accretion of a rotating finite cloud towards a central object - II. Schwarzschild spacetime

We construct a general relativistic model for the accretion flow of a rotating finite cloud of non-interacting particles infalling onto a Schwarzschild black hole. The streamlines start at a spherical shell, where boundary conditions are fixed, and are followed down to the point at which they either cross the black hole horizon or become incorporated into an equatorial thin disc. Analytic expressions for the streamlines and the velocity field are given, in terms of Jacobi elliptic functions, under the assumptions of stationarity and ballistic motion. A novel approach allows us to describe all of the possible types of orbit with a single formula. A simple numerical scheme is presented for calculating the density field. This model is the relativistic generalisation of the Newtonian one developed by Mendoza, Tejeda, Nagel, 2009 and, due to its analytic nature, it can be useful in providing a benchmark for general relativistic hydrodynamical codes and for exploring the parameter space in applications involving accretion onto black holes when the approximations of steady state and ballistic motion are reasonable ones.Comment: 12 pages, 6 figures, references and minor changes added to match version accepted for publication in MNRA

The Formation of the First Stars in the Universe

In this review, I survey our current understanding of how the very first stars in the universe formed, with a focus on three main areas of interest: the formation of the first protogalaxies and the cooling of gas within them, the nature and extent of fragmentation within the cool gas, and the physics -- in particular the interplay between protostellar accretion and protostellar feedback -- that serves to determine the final stellar mass. In each of these areas, I have attempted to show how our thinking has developed over recent years, aided in large part by the increasing ease with which we can now perform detailed numerical simulations of primordial star formation. I have also tried to indicate the areas where our understanding remains incomplete, and to identify some of the most important unsolved problems.Comment: 74 pages, 4 figures. Accepted for publication in Space Science Review

The Criminal Justice Experience of African American Cocaine Users in Arkansas

BackgroundAfrican Americans are incarcerated at rates much higher than other racial and ethnic groups in the United States.ObjectivesWe sought to qualitatively explore the relationships between ongoing involvement in the criminal justice system and continued drug use in a population of urban and rural African American cocaine users in a southern state.MethodsSemi-structured qualitative interviews were conducted among African American cocaine users in Arkansas between 2010 and 2012. Participants resided in both rural (two counties located in the eastern Arkansas Mississippi delta region) and urban (the county including the capital city of Little Rock) areas.ResultsNumerous important themes emerged from participants' narratives, including chronic involvement with the criminal justice system (being a "career criminal"), continued access to drugs while incarcerated, relapse, and reincarceration and lack of access to effective drug treatment. Conclusion/Importance: The themes which emerged from our data speak to the collective experience that many substance using populations in the United States face in dealing with the criminal justice system. Our findings highlight the need to better, more holistic ways of engaging African American substance users in community based substance use treatment and supportive services