5,062 research outputs found

    The Fair Proportion is a Shapley Value on phylogenetic networks too

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    The Fair Proportion of a species in a phylogenetic tree is a very simple measure that has been used to assess its value relative to the overall phylogenetic diversity represented by the tree. It has recently been proved by Fuchs and Jin to be equal to the Shapley Value of the coallitional game that sends each subset of species to its rooted Phylogenetic Diversity in the tree. We prove in this paper that this result extends to the natural translations of the Fair Proportion and the rooted Phylogenetic Diversity to rooted phylogenetic networks. We also generalize to rooted phylogenetic networks the expression for the Shapley Value of the unrooted Phylogenetic Diversity game on a phylogenetic tree established by Haake, Kashiwada and Su.Comment: 12 page

    Commentary on session III: U.S.-Mexico remittances: recent trends and measurement issues

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    Summary and discussion of the three papers in this session: "Leveraging remittances for development" by Dilip Ratha; "Remittances and their microeconomic impacts: evidence from Latin America" by Catalina Amuedo-Dorantes; and "The relationship between international migration, trade, and development: some paradoxes and findings" by J. Edward Taylor. ; The rest of this commentary explores recent trends in U.S.?Mexico remittances, explaining how they are measured and comparing them with forecasts of remittances based on an econometric model and with trends in other developing countries.Emigration and immigration ; International trade ; Economic development ; Developing countries ; Emigrant remittances ; Econometric models ; Mexico

    The impact of illegal immigration and enforcement on border crime rates

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    Border crime rates lie consistently below the national average. In the 1990s, however, while there as a large decline in property-related crime along the U.S.-Mexico border, violent crime rates began to converge to the national average. At the same time, legal and illegal immigration from Mexico surged and border enforcement rose to unprecedented levels. In this paper, we investigate the relationship between border county crime rates, immigration and enforcement since the early 1990s. We find that while the volume of illegal immigration is not related to changes in property-related crime, there is a significant positive correlation with the incidence of violent crime. This is most likely due to extensive smuggling activity along the border. Border enforcement meanwhile is significantly negatively related to crime rates. The bad news is that the deterrent effect of the border patrol diminishes over this time period, and the net impact of more enforcement on border crime since the late 1990s is zero.Emigration and immigration ; Labor supply ; Crime

    Space station integrated wall design and penetration damage control

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    A methodology was developed to allow a designer to optimize the pressure wall, insulation, and meteoroid/debris shield system of a manned spacecraft for a given spacecraft configuration and threat environment. The threat environment consists of meteoroids and orbital debris, as specified for an arbitrary orbit and expected lifetime. An overall probability of no penetration is calculated, as well as contours of equal threat that take into account spacecraft geometry and orientation. Techniques, tools, and procedures for repairing an impacted and penetrated pressure wall were developed and tested. These techniques are applied from the spacecraft interior and account for the possibility of performing the repair in a vacuum. Hypervelocity impact testing was conducted to: (1) develop and refine appropriate penetration functions, and (2) determine the internal effects of a penetration on personnel and equipment

    Space station integrated wall design and penetration damage control

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    The analysis code BUMPER executes a numerical solution to the problem of calculating the probability of no penetration (PNP) of a spacecraft subject to man-made orbital debris or meteoroid impact. The codes were developed on a DEC VAX 11/780 computer that uses the Virtual Memory System (VMS) operating system, which is written in FORTRAN 77 with no VAX extensions. To help illustrate the steps involved, a single sample analysis is performed. The example used is the space station reference configuration. The finite element model (FEM) of this configuration is relatively complex but demonstrates many BUMPER features. The computer tools and guidelines are described for constructing a FEM for the space station under consideration. The methods used to analyze the sensitivity of PNP to variations in design, are described. Ways are suggested for developing contour plots of the sensitivity study data. Additional BUMPER analysis examples are provided, including FEMs, command inputs, and data outputs. The mathematical theory used as the basis for the code is described, and illustrates the data flow within the analysis

    Tailoring optical fields emitted by nanometric sources

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    Here we study a simple way of controlling the emitted fields of sub-wavelength nanometric sources. The system consists of arrays of nanoparticles (NPs) embedded in optical active media. The key concept is the careful tuning of NP's damping factors, which changes the eigenmode's decay rates of the whole array. This, at long time, leads to a locking of relative phases and frequencies of individual localized-surfaces-plasmons (LSPs) and, thus, controlls the emitted field. The amplitude of the LSP's oscillations can be kept constant by embedding the system in optical active media. In the case of full loss compensation, this implies that, not only the relative phases, but also the amplitudes of the LSPs remain fixed, leading us, additionally, to interpret the process as a new example of synchronization. The proposed approach can be used as a general way of controlling and designing the electromagnetic fields emitted by nanometric sources, which can find applications in optoelectronic, nanoscale lithography and probing microscopy
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