The orbital siphon : A new space elevator concept

A new concept for propellantless payload transfer from the surface of the Earth to Earth escape is presented. Firstly, a simple model of a payload ascending or descending a conventional space elevator is developed to explore the underlying dynamics of the problem. It shown that an unconstrained payload at rest on a space elevator at synchronous radius is in an unstable equilibrium, and that this instability can be used to motivate the development of a new concept for payload transfer. It will be shown that a chain of connected payloads stretching from the surface of the Earth to beyond synchronous radius can be assembled which will lift new payloads at the bottom of the chain, while releasing payloads from the top of the chain. The complete system therefore acts as an 'orbital siphon', transporting mass from the surface of the Earth to Earth escape without the need for external work to be done. Indeed the system performs net work by transferring energy from the Earth's rotation to the escaping mass. The dynamics of the siphon effect are explored and key engineering issues are identified

The WiggleZ Dark Energy Survey: constraining the evolution of Newton's constant using the growth rate of structure

We constrain the evolution of Newton's constant using the growth rate of large-scale structure measured by the WiggleZ Dark Energy Survey in the redshift range $0.1 < z < 0.9$. We use this data in two ways. Firstly we constrain the matter density of the Universe, \omms (assuming General Relativity), and use this to construct a diagnostic to detect the presence of an evolving Newton's constant. Secondly we directly measure the evolution of Newton's constant, \Geff, that appears in Modified Gravity theories, without assuming General Relativity to be true. The novelty of these approaches are that, contrary to other methods, they do not require knowledge of the expansion history of the Universe, $H(z)$, making them model independent tests. Our constraints for the second derivative of Newton's constant at the present day, assuming it is slowly evolving as suggested by Big Bang Nucleosynthesis constraints, using the WiggleZ data is \ddotGeff(t_0)=-1.19\pm 0.95\cdot 10^{-20}h^2 \textrm{yr}^{-2}, where $h$ is defined via $H_0=100 h km s^{-1}Mpc^{-1}$, while using both the WiggleZ and the Sloan Digital Sky Survey Luminous Red Galaxy (SDSS LRG) data is \ddotGeff(t_0)=-3.6\pm 6.8\cdot 10^{-21}h^2 \rm{yr}^{-2}, both being consistent with General Relativity. Finally, our constraint for the rms mass fluctuation $\sigma_8$ using the WiggleZ data is $\sigma_8=0.75 \pm 0.08$, while using both the WiggleZ and the SDSS LRG data $\sigma_8=0.77 \pm 0.07$, both in good agreement with the latest measurements from the Cosmic Microwave Background radiation.Comment: 15 pages, 5 figures, 4 tables, changes match the published versio

The Declining Number of Youth in Custody in the Juvenile Justice System

During the last decade, custody rates for youth in the US have declined significantly. This Focus describes this trend by race/ethnicity, gender, and state. Measured by arrest rates, juvenile crime, especially serious crime, has also decreased during this period, contrary to a prevalent misconception that young people pose a growing threat to society

Novel payload dynamics on space elevator systems

A simple model of a payload ascending or descending a space elevator is developed to explore the underlying dynamics of the problem. It shown that an unconstrained payload at rest on a space elevator at synchronous radius is in an unstable equilibrium, and that this instability can be used to motivate the development of new ideas for payload transfer. In particular, it will be shown that a chain of connected payloads can be assembled which will lift new payloads at the bottom of the chain, while releasing payloads from the top of the chain. The system therefore acts as an 'orbital siphon', transporting mass from the surface of the Earth to escape speed without the need for external work to be done

Sensible heat receiver for solar dynamic space power system

A sensible heat receiver considered in this study uses a vapor grown carbon fiber-carbon (VGCF/C) composite as the thermal storage media and was designed for a 7 kW Brayton engine. The proposed heat receiver stores the required energy to power the system during eclipse in the VGCF/C composite. The heat receiver thermal analysis was conducted through the Systems Improved Numerical Differencing Analyzer and Fluid Integrator (SINDA) software package. The sensible heat receiver compares well with other latent and advanced sensible heat receivers analyzed in other studies while avoiding the problems associated with latent heat storage salts and liquid metal heat pipes. The concept also satisfies the design requirements for a 7 kW Brayton engine system. The weight and size of the system can be optimized by changes in geometry and technology advances for this new material

Panning for gold: designing pedagogically-inspired learning nuggets

Tools to support teachers and learning technologists in the creation of effective learning designs are currently in their infancy. This paper describes a metadata model, devised to assist in the conception and design of new learning activities, that has been developed, used and evaluated over a period of three years. The online tool that embodies this model was not originally intended to produce runtime executable code such as IMS-LD, but rather focussed on assisting teachers in the thought processes involved in selecting appropriate methods, tools, student activities and assessments to suit the required learning objectives. Subsequently, we have modified the RELOAD editor such that the output from our tool can be translated into IMS-LD. The contribution of this paper is the comparison of our data model with that of IMS-LD, and the analysis of how each can inform the other

The Long-Term Effects of Divorce and Parental Discord on the Adult-Child\u27s Socioeconomic Attainment

Some of the most recent divorce research suggests that a better descriptor of adult socioeconomic attainment is not divorce, nor its intermediary causes, but rather the existence of hostile and aggressive parental behavior during childhood (Keister, 2005; Amato, 2005). Accordingly, divorce may just be another measure of a more significant cause of diminished income attainment among children of divorce: poorly managed anger by parents. The present study seeks to explore these complex relationships and establish that the parental relationships in a household are as important as the legal outcome of the marriage itself with regard to long run adultchild effects

External Tank (ET) Thermal Protection System (TPS) Non-Destructive Evaluation (NDE) Super Problem Resolution Team (SPRT) Activities

No abstract availabl

Predicting space climate change

The recent decline in the open magnetic flux of the Sun heralds the end of the Grand Solar Maximum (GSM) that has persisted throughout the space age, during which the largest‐fluence Solar Energetic Particle (SEP) events have been rare and Galactic Cosmic Ray (GCR) fluxes have been relatively low. In the absence of a predictive model of the solar dynamo, we here make analogue forecasts by studying past variations of solar activity in order to evaluate how long‐term change in space climate may influence the hazardous energetic particle environment of the Earth in the future. We predict the probable future variations in GCR flux, near‐Earth interplanetary magnetic field (IMF), sunspot number, and the probability of large SEP events, all deduced from cosmogenic isotope abundance changes following 24 GSMs in a 9300‐year record