33 research outputs found
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