Strong deflection lensing by charged black holes in scalar-tensor gravity

We examine a class of charged black holes in scalar-tensor gravity as gravitational lenses. We find the deflection angle in the strong deflection limit, from which we obtain the positions and the magnifications of the relativistic images. We compare our results with those corresponding to the Reissner-Norstrom spacetime and we analyze the observational aspects in the case of the Galactic supermassive black hole.Comment: 12 pages, 3 figures; v2: improved version, new references adde

Regular phantom black hole gravitational lensing

We study regular and asymptotically flat phantom black holes as gravitational lenses. We obtain the deflection angle in both the weak and the strong deflection limits, from which we calculate the positions, magnifications, and time delays of the images. We compare our results with those corresponding to the Schwarzschild solution and to the vacuum Brans-Dicke black hole.Comment: 14 pages, 4 figures; v2: improved and extended version, new references added. Accepted for publication in Phys. Rev.

One-Way Compatibility, Two-Way Compatibility and Entry in Network Industries

We study the strategic choice of compatibility between two initially incompatible network goods in a two-stage game played by an incumbent and an entrant firm. Compatibility may be achieved by means of a converter. We derive a number of results under different assumptions about the nature of the converter (one-way \emph{vs} two-way) and the existence of property rights. In the case of a two-way converter, which can only be supplied by the incumbent, incompatibility will result in equilibrium. When both firms can build a one-way converter and there are no property rights on the necessary technical specifications, the unique equilibrium involves full compatibility. Finally, when each firm has property rights on its technical specifications, full incompatibility and preemption are again observed at the equilibrium. With incompatibility, entry deterrence occurs for sufficiently strong network effects. The welfare analysis shows that the equilibrium compatibility regime is socially inefficient for most levels of the network effects.Network externalities, one-way compatibility, two-way compatibility, entry

One-Way Compatibility, Two-Way Compatibility and Entry in Network Industries

We study the strategic choice of compatibility between two initially incompatible software packages in a two-stage game by an incumbent and an entrant firm. Consumers enjoy network externality in consumption and maximise expected surplus over the two periods. Compatibility may be achieved by means of a converter. We derive a number of results under diÆerent assumptions about the nature of the converter (one-way vs two-way) and the existence of property rights. In the case of a two-way converter, which can only be supplied by the incumbent, incompatibility will result in equilibrium and depending on the strength of network externalities the incumbent may deter entry. When both firms can build a one-way converter and there are no property rights on the necessary technical specifications, the only fulfilled expectations subgame perfect equilibrium involves full compatibility. Finally, when each firm has property rights on its technical specifications, full incompatibility and preemption are again observed at the equilibrium. Entry deterrence will then occur for su±ciently strong network eÆects. The analysis generalises to any market where network externalities are present.

Foreign Direct Investment in the Philippines: A Review of the Literature

This study reviews and synthesizes the literature on foreign direct investment in the Philippines in terms of the size, composition, determinants and the benefits and costs of direct investment in the Philippines. The study shows that while the benefits from foreign investments are not extensive, the costs are quite substantial. As it lists the benefits cited by the proponents of foreign investments, it makes a qualifying statement that few have really attempted to make a comprehensive cost and benefit analysis for the Philippines. Proper analysis of many of the studies can only be possible when more studies linking the subject matter with other areas of the economy and with the country’s economic development in general are made.inflows, foreign direct investment

Publish/subscribe protocol in wireless sensor networks: improved reliability and timeliness

The rapidly-evolving demand of applications using wireless sensor networks in several areas such as building and industrial automation or smart cities, among other, makes it necessary to determine and provide QoS support mechanisms which can satisfy the requirements of applications. In this paper we propose a mechanism that establishes different QoS levels, based on Publish/Subscribe model for wireless networks to meet application requirements, to provide reliable delivery of packet and timeliness. The first level delivers packets in a best effort way. The second one intends to provide reliable packet delivery with a novel approach for Retransmission Timeout (RTO) calculation, which adjusts the RTO depending on the subscriber Packet Delivery Ratio (PDR). The third one provides the same reliable packet delivery as the second one, but in addition, it provides data aggregation trying to be efficient in terms of energy consumption and the use of network bandwidth. The last one provides timeliness in the packet delivery. We evaluate each QoS Level with several performance metrics such as PDR, Message Delivery Ratio, Duplicated and Retransmitted Packet Ratio and Packet Timeliness Ratio to demonstrate that our proposal provides significant improvements based on the increase of the PDR obtained.Peer ReviewedPostprint (author's final draft

An Econometric Model for Forecasting Internal Taxes: A National Level Approach

Tax revenue forecasting is an essential input in the budgetary process. The ability to project and forecast future tax collections is an important element in the identification of future budgetary gaps and in the planning of new tax measures that may be needed to meet these needs. In addition, taxes play a major role in financing of the country’s economic and social development. It is the purpose of this paper to develop, specify and estimate a forecasting model for internal taxes. In particular, this paper attempts to estimate a tax-forecasting model that has a higher level of disaggregation.econometric modeling, taxation