480 research outputs found

    A Potential Aid in the Target Selection for the Comet Interceptor Mission

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    The upcoming Comet Interceptor mission involves a parking phase around the Sun-Earth L2 point before transferring to intercept the orbit of a long period comet, interstellar object or a back-up target in the form of a short-period comet. The target is not certain to be known before the launch in 2029. During the parking phase there may thus arise a scenario wherein a decision needs to be taken of whether to go for a particular comet or whether to discard that option in the hope that a better target will appear within a reasonable time frame later on. We present an expectation value-based formalism that could aid in the associated decision making provided that outlined requirements for its implementation exist

    Development of a Communication Strategy to Reduce Violence against Children in South Africa: A Social-Ecological Approach

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    Research on violence against children, though extensive, has not been effectively deployed for the development and tailoring of communication efforts aimed at specific national, local and cultural contexts within which such violence occurs. This article presents a staged, multi-sectoral communication strategy to reduce the incidence of violence against children in South Africa. Drawing on formative data collected through a literature review, key informant interviews, focus groups, and a stakeholder review meeting, the research team, in collaboration with UNICEF South Africa, formulated a communication strategy aimed at combatting violence against children. The data analysis and strategy development within a socialecological framework sought to identify factors at multiple levels that contribute to violence against children in the South African context. The communication strategy is designed to achieve positive social and behaviour change outcomes in South Africa with respect to the treatment of children, and also to provide an approach as well as specific elements that are potentially replicable to some extent in other countries.CA201

    A Single Deformed Bow Shock for Titan-Saturn System

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    During periods of high solar wind pressure, Saturn's bow shock is pushed inside Titan's orbit exposing the moon and its ionosphere to the solar wind. The Cassini spacecraft's T96 encounter with Titan occurred during such a period and showed evidence for shocks associated with Saturn and Titan. It also revealed the presence of two foreshocks: one prior to the closest approach (foreshock 1) and one after (foreshock 2). Using electromagnetic hybrid (kinetic ions and fluid electrons) simulations and Cassini observations, we show that the origin of foreshock 1 is tied to the formation of a single deformed bow shock for the Titan‐Saturn system. We also report the observations of a structure in foreshock 1 with properties consistent with those of spontaneous hot flow anomalies formed in the simulations and previously observed at Earth, Venus, and Mars. The results of hybrid simulations also show the generation of oblique fast magnetosonic waves upstream of the outbound Titan bow shock in agreement with the observations of large‐amplitude magnetosonic pulsations in foreshock 2. We also discuss the implications of a single deformed bow shock for new particle acceleration mechanisms and also Saturn's magnetopause and magnetosphere

    They Destroy the Reproductive System : Exploring the Belief that Modern Contraceptive Use Causes Infertility

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    © 2018 The Authors. Studies in Family Planning published by John Wiley & Sons Ltd. on behalf of The Population Council, Inc. A common reason for nonuse of modern contraceptives is concern about side effects and health complications. This article provides a detailed characterization of the belief that modern contraceptives cause infertility, and an examination of how this belief arises and spreads, and why it is so salient. We conducted focus group discussions and key informant interviews in three rural communities along Kenya\u27s eastern coast, and identified the following themes: (1) the belief that using modern contraception at a young age or before childbirth can make women infertile is widespread; (2) according to this belief, the most commonly used methods in the community were linked to infertility; (3) when women observe other women who cannot get pregnant after using modern contraceptives, they attribute the infertility to the use of contraception; (4) within the communities, the primary goal of marriage is childbirth and thus community approval is rigidly tied to childbearing; and, therefore (5) the social consequences of infertility are devastating. These findings may help inform the design of programs to address this belief and reduce unmet need

    Titan's interaction with the supersonic solar wind

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    After 9 years in the Saturn system, the Cassini spacecraft finally observed Titan in the supersonic and super-Alfvénic solar wind. These unique observations reveal that Titan?s interaction with the solar wind is in many ways similar to unmagnetized planets Mars and Venus and active comets in spite of the differences in the properties of the solar plasma in the outer solar system. In particular, Cassini detected a collisionless, supercritical bow shock and a well-defined induced magnetosphere filled with mass-loaded interplanetary magnetic field lines, which drape around Titan?s ionosphere. Although the flyby altitude may not allow the detection of an ionopause, Cassini reports enhancements of plasma density compatible with plasma clouds or streamers in the flanks of its induced magnetosphere or due to an expansion of the induced magnetosphere. Because of the upstream conditions, these observations may be also relevant to other bodies in the outer solar system such as Pluto, where kinetic processes are expected to dominate.Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Hamilton, D. C.. University of Maryland; Estados UnidosFil: Kurth, W. S.. University of Iowa; Estados UnidosFil: Hospodarsky, G.. University of Iowa; Estados UnidosFil: Mitchell, D.. University Johns Hopkins; Estados UnidosFil: Sergis, N.. Academy of Athens; GreciaFil: Edberg, N. J. T.. Swedish Institute of Space Physics,; SueciaFil: Dougherty, M. K.. Imperial College London; Reino Unid

    Space Weather in the Saturn-Titan System

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    New evidence based on Cassini magnetic field and plasma data has revealed that the discovery of Titan outside Saturn’s magnetosphere during the T96 flyby on 2013 December 1 was the result of the impact of two consecutive interplanetary coronal mass ejections (ICMEs) that left the Sun in 2013 early November and interacted with the moon and the planet. We study the dynamic evolution of Saturn's magnetopause and bow shock, which evidences a magnetospheric compression from late November 28 to December 4 (at least), under prevailing solar wind dynamic pressures of 0.16-0.3 nPa. During this interval, transient disturbances associated with the two ICMEs are observed, allowing for the identification of their magnetic structures. By analyzing the magnetic field direction, and the pressure balance in Titan’s induced magnetosphere, we show that Cassini finds Saturn’s moon embedded in the second ICME after being swept by its interplanetary shock and amid a shower of solar energetic particles that may have caused dramatic changes in the moon’s lower ionosphere. Analyzing a list of Saturn's bow shock crossings during 2004-2016, we find that the magnetospheric compression needed for Titan to be in the supersonic solar wind can be generally associated with the presence of an ICME or a corotating interaction region. This leads to the conclusion that Titan would rarely face the pristine solar wind, but would rather interact with transient solar structures under extreme space weather conditions
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