Cascading Cosmology

We develop a fully covariant, well-posed 5D effective action for the 6D cascading gravity brane-world model, and use this to study cosmological solutions. We obtain this effective action through the 6D decoupling limit, in which an additional scalar degree mode, \pi, called the brane-bending mode, determines the bulk-brane gravitational interaction. The 5D action obtained this way inherits from the sixth dimension an extra \pi self-interaction kinetic term. We compute appropriate boundary terms, to supplement the 5D action, and hence derive fully covariant junction conditions and the 5D Einstein field equations. Using these, we derive the cosmological evolution induced on a 3-brane moving in a static bulk. We study the strong- and weak-coupling regimes analytically in this static ansatz, and perform a complete numerical analysis of our solution. Although the cascading model can generate an accelerating solution in which the \pi field comes to dominate at late times, the presence of a critical singularity prevents the \pi field from dominating entirely. Our results open up the interesting possibility that a more general treatment of degravitation in a time-dependent bulk, or taking into account finite brane-thickness effects, may lead to an accelerating universe without a cosmological constant.Comment: [v2] 27 pages, 2 figures, corrected typos, expanded discussion of late-time cosmological behavio

Reliability assessment of the 1964 mariner mars spacecraft

Numerical exercise of reliability model of Mariner Mars spacecraft and spacecraft subsystems reliabilit

Terrestrial Planet Formation in Extra-Solar Planetary Systems

Terrestrial planets form in a series of dynamical steps from the solid component of circumstellar disks. First, km-sized planetesimals form likely via a combination of sticky collisions, turbulent concentration of solids, and gravitational collapse from micron-sized dust grains in the thin disk midplane. Second, planetesimals coalesce to form Moon- to Mars-sized protoplanets, also called "planetary embryos". Finally, full-sized terrestrial planets accrete from protoplanets and planetesimals. This final stage of accretion lasts about 10-100 Myr and is strongly affected by gravitational perturbations from any gas giant planets, which are constrained to form more quickly, during the 1-10 Myr lifetime of the gaseous component of the disk. It is during this final stage that the bulk compositions and volatile (e.g., water) contents of terrestrial planets are set, depending on their feeding zones and the amount of radial mixing that occurs. The main factors that influence terrestrial planet formation are the mass and surface density profile of the disk, and the perturbations from giant planets and binary companions if they exist. Simple accretion models predicts that low-mass stars should form small, dry planets in their habitable zones. The migration of a giant planet through a disk of rocky bodies does not completely impede terrestrial planet growth. Rather, "hot Jupiter" systems are likely to also contain exterior, very water-rich Earth-like planets, and also "hot Earths", very close-in rocky planets. Roughly one third of the known systems of extra-solar (giant) planets could allow a terrestrial planet to form in the habitable zone.Comment: 19 pages, 5 figures. To appear in the proceedings of IAU Symposium 249: Exoplanets: Detection, Formation and Dynamics, held in Suzhou, China, Oct 22-26 200

Using a time-series analysis to evaluate a female youth-driven physical activity-based life skills program based on the Teaching Personal and Social Responsibility model

The Girls Just Wanna Have Fun program is a physical activity-based life skills program that was developed in response to the highlighted need to increase levels of physical activity in female youth and is based on the TPSR model (Hellison, 1995). The purpose of this research was to examine how well the implementation of the program adhered to the five levels of the TPSR model using a time series analysis. Participants and leaders completed evaluations of the five TPSR levels at the end of each session. The youth also completed the Personal and Social Responsibility Questionnaire at the beginning and end of the program. Results indicated that participants’ self-ratings of the five TPSR levels varied based on type of life skill and physical activity of each program session, but overall showed a gradual upward trend throughout the program. Dependent t-tests revealed a significant difference for leadership from the start to the end of the program. This research aids in understanding the process in which youth development programs, specifically those utilizing the TPSR model, can be effectively implemented. Practical recommendations for future programming are discussed.Girls Just Wanna Have Fun es un programa de habilidades para la vida mediante la actividad física basado en el modelo TPSR (Hellison, 1995) que se desarrolló para responder a la necesidad de aumentar los niveles de actividad física de las mujeres jóvenes. El propósito de esta investigación fue examinar, utilizando un análisis de series de tiempo, la implementación del programa en relación con los cinco niveles del modelo TPSR. Los participantes y los líderes completaron las evaluaciones de los cinco niveles TPSR al final de cada sesión. Las jóvenes realizaron también el cuestionario de Responsabilidad Personal y Social al inicio y al final del programa. Los resultados indican que las autoevaluaciones de los participantes en los cinco niveles TPSR variaron en función del tipo de habilidades para la vida y de la actividad física de cada sesión; aunque, en general, mostraron una tendencia gradual al alza durante todo el programa. Pruebas t dependientes revelaron diferencias significativas entre el principio y el final del programa en lo concerniente al liderazgo. Este estudio ayuda a comprender mejor los procesos de aplicación efectiva de los programas de desarrollo de la juventud, especialmente los que utilizan el modelo TPSR. Finalmente, se discuten también recomendaciones prácticas para la realización de programaciones futuras

Participants' experiences of a community-based sport program: a vehicle to positive youth development

Researchers assert that sport can be a context that enhances youth development. As a result, an increasing number of community sport programs have begun to incorporate life skills (Wenger & Foutz, 2010). However, formal evaluations of such programs are sparse and therefore little is known regarding the ir effectiveness. The purpose of this study was to examine the perceived impact of a barrier - free youth sport program. Results indicated that youth perceived PAL (Police Athletic League) as a program where they develop athletic skills (M=3.51), put forth effort (M=3.32), develop a sense of belonging in their community (M=3.12), establish diverse peer relationships (M=3.11), and learn how to take initiative (M=3.10). Results from interviews supported these findings as the themes that emerged detailed PAL as a fun, safe, and accessible environment that enables friendships to emerge, acts as a catalyst for the development of life skills, and facilitates the transference of skills to outside domains.Los investigadores afirman que el deporte puede ser un contexto en el que se favorece el desarrollo juvenil. En consecuencia, un número cada vez mayor de programas deportivos comunitarios han comenzado a incorporar habilidades para la vida (Wenger y Foutz, 2010). Sin embargo, las evaluaciones formales de este tipo de programas son escasa s y, por lo tanto, poco se sabe acerca de su eficacia. El propósito de este estudio fue examinar la percepción del impacto de un programa de deporte juvenil sin barreras. Los resultados indicaron que la juventud percibe el PAL (Police Athletic League) como un programa donde se desarrollan las habilidades deportivas (M=3.51), se promueve el esfuerzo (M=3.32), se desarrolla un sentido de pertenencia a su comunidad (M=3.12), se establecen diversas relaciones entre pares (M=3,11), y se aprende a tomar la iniciativa (M = 3,10). Las entrevistas confimaron dichos resultados destacando estos temas a la hora de describir el PAL: un ambiente divertido, seguro y accesible que permite que surjan amistades, que actúa como un catalizador para el desarrollo de habilidades para la vida, y que facilita la transferencia de competencias a otros dominios externos

Implementing a network for electronic surveillance reporting from public health reference laboratories: an international perspective.

Electronic data reporting from public health laboratories to a central site provides a mechanism for public health officials to rapidly identify problems and take action to prevent further spread of disease. However, implementation of reference laboratory systems is much more complex than simply adopting new technology, especially in international settings. We describe three major areas to be considered by international organizations for successful implementation of electronic reporting systems from public health reference laboratories: benefits of electronic reporting, planning for system implementation (e.g., support, resources, data analysis, country sovereignty), and components of system initiation (e.g., authority, disease definition, feedback, site selection, assessing readiness, problem resolution). Our experience with implementation of electronic public health laboratory data management and reporting systems in the United States and working with international organizations to initiate similar efforts demonstrates that successful reference laboratory reporting can be implemented if surveillance issues and components are planned

Being Like Both: Library Instruction Methods that Outshine the One-Shot

Marshall University librarians\u27 efforts to improve library instruction are explored. A history of the libraries\u27 Digital Learning Team (DLT) and its developmental phases is provided, as well as interpretations of evaluative data collected from embedded students. Data from the iSkills assessment of student information literacy skills are considered. The results suggest that library instruction best facilitates student learning when it aligns with specific research goals, utilizes a variety of learning styles, and allows time for practice and assessment. Student feedback suggests the need for additional instruction on citation and emphasis on increasing students\u27 confidence in their research skills

The tree cut and merge algorithm for estimation of network reliability

This article presents Monte Carlo techniques for estimating network reliability. For highly reliable networks, techniques based on graph evolution models provide very good performance. However, they are known to have significant simulation cost. An existing hybrid scheme (based on partitioning the time space) is available to speed up the simulations; however, there are difficulties with optimizing the important parameter associated with this scheme. To overcome these difficulties, a new hybrid scheme (based on partitioning the edge set) is proposed in this article. The proposed scheme shows orders of magnitude improvement of performance over the existing techniques in certain classes of network. It also provides reliability bounds with little overhead.K.P. Hui, N. Bean, M. Kraetzl and D. Kroes