63,990 research outputs found

    The Role of NGOs in Human Security

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    Human security is fundamentally concerned with helping people to deal with unforeseeable threats and sudden downturns, whether international financial crises, environmental disasters or incapacitating illnesses. In this paper I argue that NGOs, as one of the most visible sets of actors in the related fields of human development and human rights, can play a significant role in helping to achieve human security. NGOs are especially well suited to action for human security because of their size and reach, closeness to local populations, willingness to confront the status quo, and ability to address transnational threats through coalition-building. While NGOs face many obstacles in reorienting their activities explicitly towards human security, including the cyclical nature of the aid monies on which many of them depend and the high costs of networking, I argue that the human security framework will nonetheless attract many NGOs to its approach.This publication is Hauser Center Working Paper No. 12. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers

    I Did What Last Night? Adolescent Risky Sexual Behaviors and Substance Abuse

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    Risky sexual behaviors by teenagers have shown to be strongly correlated with drug and alcohol consumption. The purpose of this study is to examine the question of whether alcohol and drug use increases the likelihood that teenagers will engage in four risky sexual behaviors: having sex, sex with multiple partners, sex without a condom, and sex without birth control. Two-stage least squares and a reduced form model are used to account for the potential endogeneity of substance use. The finding that alcohol consumption (as defined by either heavy drinking or drinking any amount) is unrelated to the probability of having sex is consistent with the findings of previous studies that also account for the potential endogeneity of alcohol consumption. The findings imply that the risky behaviors of sexually active teens, who may have made the decision long ago to become sexually active, might be altered through policies designed to reduce alcohol consumption.

    Considerate Approaches to Achieving Sufficiency for ABC model selection

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    For nearly any challenging scientific problem evaluation of the likelihood is problematic if not impossible. Approximate Bayesian computation (ABC) allows us to employ the whole Bayesian formalism to problems where we can use simulations from a model, but cannot evaluate the likelihood directly. When summary statistics of real and simulated data are compared --- rather than the data directly --- information is lost, unless the summary statistics are sufficient. Here we employ an information-theoretical framework that can be used to construct (approximately) sufficient statistics by combining different statistics until the loss of information is minimized. Such sufficient sets of statistics are constructed for both parameter estimation and model selection problems. We apply our approach to a range of illustrative and real-world model selection problems

    Glass in the submarine section of the HSDP2 drill core, Hilo, Hawaii

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    The Hawaii Scientific Drilling Project recovered ~3 km of basalt by coring into the flank of Mauna Kea volcano at Hilo, Hawaii. Rocks recovered from deeper than ~1 km were deposited below sea level and contain considerable fresh glass. We report electron microprobe analyses of 531 glasses from the submarine section of the core, providing a high-resolution record of petrogenesis over ca. 200 Kyr of shield building of a Hawaiian volcano. Nearly all the submarine glasses are tholeiitic. SiO2 contents span a significant range but are bimodally distributed, leading to the identification of low-SiO2 and high-SiO2 magma series that encompass most samples. The two groups are also generally distinguishable using other major and minor elements and certain isotopic and incompatible trace element ratios. On the basis of distributions of high- and low-SiO2 glasses, the submarine section of the core is divided into four zones. In zone 1 (1079–~1950 mbsl), most samples are degassed high-SiO2 hyaloclastites and massive lavas, but there are narrow intervals of low-SiO2 hyaloclastites. Zone 2 (~1950–2233 mbsl), a zone of degassed pillows and hyaloclastites, displays a continuous decrease in silica content from bottom to top. In zone 3 (2233–2481 mbsl), nearly all samples are undegassed low-SiO2 pillows. In zone 4 (2481–3098 mbsl), samples are mostly high-SiO2 undegassed pillows and degassed hyaloclastites. This zone also contains most of the intrusive units in the core, all of which are undegassed and most of which are low-SiO2. Phase equilibrium data suggest that parental magmas of the low-SiO2 suite could be produced by partial melting of fertile peridotite at 30–40 kbar. Although the high-SiO2 parents could have equilibrated with harzburgite at 15–20 kbar, they could have been produced neither simply by higher degrees of melting of the sources of the low-SiO2 parents nor by mixing of known dacitic melts of pyroxenite/eclogite with the low-SiO2 parents. Our hypothesis for the relationship between these magma types is that as the low-SiO2 magmas ascended from their sources, they interacted chemically and thermally with overlying peridotites, resulting in dissolution of orthopyroxene and clinopyroxene and precipitation of olivine, thereby generating high-SiO2 magmas. There are glasses with CaO, Al2O3, and SiO2 contents slightly elevated relative to most low-SiO2 samples; we suggest that these differences reflect involvement of pyroxene-rich lithologies in the petrogenesis of the CaO-Al2O3-enriched glasses. There is also a small group of low-SiO2 glasses distinguished by elevated K2O and CaO contents; the sources of these samples may have been enriched in slab-derived fluid/melts. Low-SiO2 glasses from the top of zone 3 (2233–2280 mbsl) are more alkaline, more fractionated, and incompatible-element-enriched relative to other glasses from zone 3. This excursion at the top of zone 3, which is abruptly overlain by more silica-rich tholeiitic magmas, is reminiscent of the end of Mauna Kea shield building higher in the core

    Moduli of Tropical Plane Curves

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    We study the moduli space of metric graphs that arise from tropical plane curves. There are far fewer such graphs than tropicalizations of classical plane curves. For fixed genus gg, our moduli space is a stacky fan whose cones are indexed by regular unimodular triangulations of Newton polygons with gg interior lattice points. It has dimension 2g+12g+1 unless g3g \leq 3 or g=7g = 7. We compute these spaces explicitly for g5g \leq 5.Comment: 31 pages, 25 figure
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