9,283 research outputs found
High level sill and dyke intrusions initiated from rapidly buried mafic lava flows in scoria cones of Tongoa, Vanuatu (New Hebrides), South Pacific
Scoria cones are generally considered to grow rapidly in days to weeks or months. During their growth lava flows may be fed onto the cone surface from lava-lake breaches, or form by coalescence of spatter; such flows are preserved interbedded with scoria lapilli and ash beds. On Tongoa, an island of the Vanuatu volcanic arc in the South Pacific, a series of scoria cones developed during the Holocene, forming a widespread monogenetic volcanic field. Half sections of scoria cones along the coast expose complex interior architecture cone architectures. On the western side of Tongoa Island a scoria cone remnant with steeply crater-ward dipping beds of scoria ash and lapilli contains various dm-to-m thick lava flows, which are connected by irregular dikes cutting obliquely across the beds of the cone. The lava flows are coherent igneous bodies with well-developed flow top and basal breccias. The lavas interbedded with the cone-forming layers are part of a larger (up to 7 m thick) body that is connected to dykes and sills of irregular geometries that intrude the cone's pyroclastic layers. This 3D relationship suggests that the lava flows were buried quickly under the accumulating scoriaceous deposits. This allowed subsequent escape of magma from the fluid interiors of flows, with the magma then squeezed upward or laterally into the accumulating pyroclastic pile. Movement of the pile above the partly mobile lava, and potential destabilisation during intrusion into the pile of lava squeezed from the flows, may signal the onset of localised cone failures, and could be implicated in development of major cone breaches (e.g. Paricutin)
Compositional variation during monogenetic volcano growth and its implications for magma supply to continental volcanic fields
Individual volcanoes of continental monogenetic volcanic fields are generally presumed to erupt single magma batches during brief eruptions. Nevertheless, in two unrelated volcanic fields (the Waipiata volcanic field, New Zealand, and the Miocene-Pliocene volcanic field in western Hungary), we have identified pronounced and systematic compositional differences among products of individual volcanoes. We infer that this indicates a two-stage process of magma supply for these volcanoes. Each volcano records: (1) intrusion of a basanitic parent magma to lower- to mid-crustal levels and its subsequent fractionation to form a tephritic residual melt;, (2) subsequent transection of this reservoir by a second batch of basanitic melt, with tephrite rising to the surface at the head of the propagating basanite dyke. Eruption at the surface then yields initial tephrite, typically erupted as pyroclasts, followed by eruption and shallow intrusion of basanite from deeper in the dyke. By analogy with similar tephrite-basanite eruptions along rift zones of intraplate ocean-island volcanoes, we infer that fractionation to tephrite would have required decades to centuries. We conclude that the two studied continental monogenetic volcanic fields demonstrate a consistent history of early magmatic injections that fail to reach the surface, followed by capture and partial eruption of their evolved residues in the course of separate and significantly later injections of basanite that extend to the surface and erupt. This systematic behaviour probably reflects the difficulty of bringing small volumes of dense, primitive magma to the surface from mantle source regions. Ascent through continental crust is aided by the presence in the dyke head of buoyant tephrite captured during transection of the earlier-emplaced melt bodies
Sunday Friends: The Working Alternative to Charity
Sunday Friends is a non-profit organization in San José, California, that provides multiple activities for families who are in need of financial support. Given the particular location of the program, most families are Latino and bilingual. Participants and program volunteers form a community at an elementary school on a couple of scheduled Sundays each month. When family members participate in activities designed to educate, improve skills, and to give back to the larger community, they earn tickets that they can redeem for items that they need and want from the Sunday Friends store. Activities include healthy cooking projects, “Thank You Letter” writing, English-as-a-Second-Language programs, crafts, and education in nutrition and financial literacy. The program’s central focus is to empower families to break out of poverty. A specific guiding principal is the developmental assets approach promoted by the Search Institute in Minneapolis (http://www.search-institute.org/). This approach encourages individuals and organizations to work together toward a common goal of supporting the healthy development of all children and youth. Healthy development is conceptualized as consisting of the development of external assets (i.e., support, empowerment, boundaries and expectations, constructive activities) and internal assets (i.e., commitment to learning, positive values, social competencies, and positive identity). The 2009 evaluation’s primary focus was on whether Sunday Friends was succeeding at fostering developmental assets for children. Other relevant indicators of success were perceptions of program effectiveness, regard for program activities, and nutrition and healthy eating habits. Data were gathered from family members (adults and minors) during program activities using written surveys administered by volunteers to the research team (most of whom were bilingual). The families were recruited in person by program staff onsite. The questionnaires were written in English and Spanish (with the choice made by respondents). Sunday Friends volunteers were recruited to the study via email by Sunday Friends staff. They completed questionnaires through an online survey platform. In all, 74 parents or guardians, 67 children or youth, and 45 volunteers participated in the data collection. Across the three sets of surveys (parents or guardians, children or youth, and volunteers), there are fairly consistent results. The families and volunteers in the Sunday Friends program believe that Sunday Friends is effectively engaging them and meeting its goals. Overall, children and youth report positive experiences at Sunday Friends. On every dimension of psychological well-being, connectedness with others, and self-efficacy, the answers provided by children and youth indicate that Sunday Friends is promoting developmental assets. In addition, parents and guardians report that Sunday Friends has positive influences on their lives. The majority of measures, whether questions about self-efficacy, the effect of Sunday Friends on their children, or improved nutrition for their family, indicate that Sunday Friends is meeting its goals. Finally, volunteers agree that the program makes an important contribution to the lives of both children and adults. They also feel that Sunday Friends enhances their awareness of the community and contributes to making their personal lives more meaningful. The survey results presented here should be interpreted with caution because all persons surveyed were continuing participants in the program, and the cross-sectional data could not detect changes over time. Despite this caution, each group’s data and triangulation across family and volunteer surveys reveal that milestones are accomplished at Sunday Friends. It is safe to conclude that Sunday Friends’ community-based approach to empowering parents and youths is achieving its goals
Development and testing of a unique carousel wind tunnel to experimentally determine the effect of gravity and the interparticle force on the physics of wind-blown particles
In the study of planetary aeolian processes the effect of gravity is not readily modeled. Gravity appears in the equations of particle motion along with the interparticle forces but the two are not separable. A wind tunnel that perimits multiphase flow experiments with wind blown particles at variable gravity was built and experiments were conducted at reduced gravity. The equations of particle motion initiation (saltation threshold) with variable gravity were experimentally verified and the interparticle force was separated. A uniquely design Carousel Wind Tunnel (CWT) allows for the long flow distance in a small sized tunnel since the test section if a continuous loop and develops the required turbulent boundary layer. A prototype model of the tunnel where only the inner drum rotates was built and tested in the KC-135 Weightless Wonder 4 zero-g aircraft. Future work includes further experiments with walnut shell in the KC-135 which sharply graded particles of widely varying median sizes including very small particles to see how interparticle force varies with particle size, and also experiments with other aeolian material
Aeolian processes aboard a Space Station: Saltation and particle trajectory analysis
The Carousel Wind Tunnel (CWT) proposed to study aeolian processes aboard a Space Station consists of two concentric rotating drums. The space between the two drums comprises the wind tunnel section. Differential rates of rotation of the two drums would provide a wind velocity with respect to either drum surface. Preliminary results of measured velocity profiles made in a CWT prototype indicate that the wall bounded boundary layer profiles are suitable to simuate flat plate turbulent boundary layer flow. The two dimensional flate plate Cartesian coordinate equations of motion of a particle moving through the air are explained. In order to assess the suitability of CWT in the analysis of the trajectories of windblown particles, a series of calculations were conducted comparing cases for gravity with those of zero gravity. Results from the calculations demonstrate that a wind tunnel of the carousel design could be fabricated to operate in a space station environment and that experiments could be conducted which would yield significant results contributing to the understanding of the physics of particle dynamics
Biodegradable Glass Compositions and Methods for Radiation Therapy
A nonradioactive glass in particulate form adapted for radiation therapy in a mammal comprise a biodegradable rare earth-lithium borate glass material of a specified composition which, upon being subjected to an effective amount of neutron irradiation, will produce a beta or gamma emitting radioisotope, the radioisotope being distributed throughout the glass material, the glass upon being introduced into a body fluid for radiation therapy being adapted to react therewith causing the radioisotope to form an insoluble compound on the surface of the glass material which is retained in the glass material and thereby prevented from escaping from the treatment site. Radioactive glasses and methods for carrying out radiation therapy with such radioactive glasses are also disclosed
Model evaluation of target product profiles of an infant vaccine against respiratory syncytial virus (RSV) in a developed country setting
Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract disease in children worldwide and is a significant cause of hospital admissions in young children in England. No RSV vaccine has been licensed but a number are under development. In this work, we present two structurally distinct mathematical models, parameterized using RSV data from the UK, which have been used to explore the effect of introducing an RSV paediatric vaccine to the National programme. We have explored different vaccine properties, and dosing regimens combined with a range of implementation strategies for RSV control. The results suggest that vaccine properties that confer indirect protection have the greatest effect in reducing the burden of disease in children under 5 years. The findings are reinforced by the concurrence of predictions from the two models with very different epidemiological structure. The approach described has general application in evaluating vaccine target product profiles
Healthcare Price Transparency: Policy Approaches and Estimated Impacts on Spending
Healthcare price transparency discussions typically focus on increasing patients' access to information about their out-of-pocket costs, but that focus is too narrow and should include other audiences -- physicians, employers, health plans and policymakers -- each with distinct needs and uses for healthcare price information. Greater price transparency can reduce U.S. healthcare spending.For example, an estimated 18 billion over the next decade. While 40 trillionin total projected health spending over the same period. In contrast, using state all-payer claims databases to gather and report hospital-specific prices might reduce spending by an estimated $61 billion over 10 years.The effects of price transparency depend critically on the intended audience, the decision-making context and how prices are presented. And the impact of price transparency can be greatly amplified if target audiences are able and motivated to act on the information. Simply providing prices is insufficient to control spending without other shifts in healthcare financing, including changes in benefit design to make patients more sensitive to price differences among providers and alternative treatments. Other reforms that can amplify the impact of price transparency include shifting from fee-for-service payments that reward providers for volume to payment methods that put providers at risk for spending for episodes of care or defined patient populations. While price transparency alone seems unlikely to transform the healthcare system, it can play a needed role in enabling effective reforms in value-based benefit design and provider payment
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