The Brown-York mass of black holes in Warped Anti-de Sitter space

We give a direct computation of the mass of black holes in Warped Anti-de Sitter space (WAdS) in terms of the Brown-York stress-tensor at the boundary. This permits to explore to what extent the holographic renormalization techniques can be applied to such type of deformation of AdS. We show that, despite some components of the boundary stress-tensor diverge and resist to be regularized by the introduction of local counterterms, the precise combination that gives the quasilocal energy density yields a finite integral. The result turns out to be in agreement with previous computations of the black hole mass obtained with different approaches. This is seen to happen both in the case of Topologically Massive Gravity and of the so-called New Massive Gravity. Here, we focus our attention on the latter. We observe that, despite other conserved charges diverge in the near boundary limit, the finite part in the large radius expansion captures the physically relevant contribution. We compute the black hole angular momentum in this way and we obtain a result that is in perfect agreement with previous calculations.Comment: 8 pages. v2 discussion and appendix added, references added. To appear in JHE

Anticommons and optimal patent policy in a model of sequential innovation

When innovation is sequential, the development of new products depends on the access to previous discoveries. As a consequence the patent system affects both the revenues and the cost of the innovator. We construct a model of sequential innovation in which an innovator uses n patented inputs in R&D to invent a new product. We ask three questions: (i) what is the net effect of patents on innovation as technologies become more complex (n increases)? (ii) are patent pools welfare enhancing? (iii) what is the optimal response of patent policy as technological complexity increases? We find that the answers to these questions depend on the degree of complementarity and substitutability between the inputs used in research

Interacting strings on AdS_3

We consider string theory on AdS_3 in terms of the Wakimoto free field representation. The scattering amplitudes for N unitary tachyons are analysed in the factorization limit and the poles corresponding to the mass-shell conditions for physical states are extracted. The vertex operators for excited levels are obtained from the residues and their properties are examined. Negative norm states are found at the second mass level.Comment: 24 pages, 2 figures, LaTeX. Substantial changes: ghosts found, conclusions modified accordingly, references added. Final version to appear in JHE

Anticommons and Optimal Patent Policy in a Model of Sequential Innovation

We present a model of sequential innovation in which an innovator uses several research inputs to invent a new good. These inputs, in turn, must be invented before they can be used by the final innovator. As a consequence, the degree of patent protection affects the revenues and cost of the innovator, but also determines the incentives to invent the research inputs in the first place. We study the effects of increases in the number of required inputs on innovation activity and optimal patent policy. We find that the probability of introducing the final innovation decreases (increases) as the number of inputs increases when inputs are complements (substitutes). We also find that the optimal strength of patents on research inputs is increasing in the degree of substitution between the inputs, but decreasing in the number of inputs for any degree of substitution.

Anticipated Capitalization of the Santiago Metro System on Housing Prices

Housing units with closer access to public transportation enjoy a higher market value than those with similar characteristics but poorer access. This difference can be explained by the less expensive cost of transport to the main workplaces and shopping areas in town. For this reason, investments in public transport infrastructure, for example, building a new metro line, are capitalized totally or partially on land property and housing prices. This work analyzes empirically the degree of capitalization on housing prices when the new Line 4 of the Santiago de Chile Metro System was built. In particular, and given that the new line started operating in December 2005, the degree of anticipated capitalization on housing prices at the moment of announcing construction of Line 4 and at the moment of informing on the basic engineering to determine the location of the stations has been estimated. A unique data base has been used, containing all home buying and selling operations in the Greater Santiago between December 2000 and March 2004. The results show that the average apartment price rose between 3.3% and 4.4% as a consequence of having announced the construction, and between 4.5% and 5.7% after information on the location of the stations was made known. This increase was not distributed evenly but depended on the distance to the closest station. An indirect effect of this kind of capitalization is that property tax collection increases if landed property is reassessed according to the price rise. This effect is not negligible in magnitude and could stand for a minimum between 14% and 20% of investment in the new metro line, which gives way to an interesting discussion with respect to the form of financing the metro network extension.Metro, Apartment Prices, Anticipated Capitalization