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.

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

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

Antispiral waves are sources in oscillatory reaction-diffusion media

Spiral and antispiral waves are studied numerically in two examples of oscillatory reaction-diffusion media and analytically in the corresponding complex Ginzburg-Landau equation (CGLE). We argue that both these structures are sources of waves in oscillatory media, which are distinguished only by the sign of the phase velocity of the emitted waves. Using known analytical results in the CGLE, we obtain a criterion for the CGLE coefficients that predicts whether antispirals or spirals will occur in the corresponding reaction-diffusion systems. We apply this criterion to the FitzHugh-Nagumo and Brusselator models by deriving the CGLE near the Hopf bifurcations of the respective equations. Numerical simulations of the full reaction-diffusion equations confirm the validity of our simple criterion near the onset of oscillations. They also reveal that antispirals often occur near the onset and turn into spirals further away from it. The transition from antispirals to spirals is characterized by a divergence in the wavelength. A tentative interpretaion of recent experimental observations of antispiral waves in the Belousov-Zhabotinsky reaction in a microemulsion is given.Comment: 10 pages, 8 figures, submitted to J. Phys. Chem. B on Feb. 20, 2004. A short account of the spiral-antispiral criterion has been given in PRL (see http://link.aps.org/abstract/PRL/v92/e089801

Elastic anomalies in glasses: the string theory understanding in the case of Glycerol and Silica

We present an implementation of the analytical string theory recently applied to the description of glasses. These are modeled as continuum media with embedded elastic string heterogeneities, randomly located and randomly oriented, which oscillate around a straight equilibrium position with a fundamental frequency depending on their length. The existence of a length distribution reflects then in a distribution of oscillation frequencies which is responsible for the Boson Peak in the glass density of states. Previously, it has been shown that such a description can account for the elastic anomalies reported at frequencies comparable with the Boson Peak. Here we start from the generalized hydrodynamics to determine the dynamic correlation function $S(k,\omega)$ associated with the coherent, dispersive and attenuated, sound waves resulting from a sound-string interference. Once the vibrational density of states has been measured, we can use it for univocally fixing the string length distribution inherent to a given glass. The density-density correlation function obtained using such distribution is strongly constrained, and able to account for the experimental data collected on two prototypical glasses: glycerol and silica. The obtained string length distribution is compatible with the typical size of elastic heterogeneities previously reported for silica and supercooled liquids, and the atomic motion associated to the string dynamics is consistent with the soft modes recently identified in large scale numerical simulations as non-phonon modes responsible for the Boson Peak. The theory is thus in agreement with the most recent advances in the understanding of the glass specific dynamics and offers an appealing simple understanding of the microscopic origin of the latter, while raising new questions on the universality or material-specificity of the string distribution properties.Comment: 15 pages, 8 figure

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

Population, Poverty, Politics and the Reproductive Health Bill

Following an earlier paper titled “Population and Poverty: The Real Score” (UPSE Discussion Paper 0415, December 2004), the present paper was first issued in August 2008 as a contribution to the public debate on the population issue that never seemed to die in this country. The debate heated up about that time in reaction to a revival of moves to push for legislation on reproductive health and family planning (RH/FP). Those attempts at legislation, however, failed in the 13th Congress, and again in the 14th Congress. Since late last year, the debate has been heating up further on the heels of President Noy Aquino’s pronouncements seeming to favor RH/FP, though he prefers the nomenclature “responsible parenthood”. With some updating of the data, this paper remains as relevant as ever to the ongoing public debate. It is being re-issued as a Discussion Paper for wider circulation.population, reproductive health, poverty, Philippines