Hyperbolic slicings of spacetime: singularity avoidance and gauge shocks

I study the Bona-Masso family of hyperbolic slicing conditions, considering in particular its properties when approaching two different types of singularities: focusing singularities and gauge shocks. For focusing singularities, I extend the original analysis of Bona et. al and show that both marginal and strong singularity avoidance can be obtained for certain types of behavior of the slicing condition as the lapse approaches zero. For the case of gauge shocks, I re-derive a condition found previously that eliminates them. Unfortunately, such a condition limits considerably the type of slicings allowed. However, useful slicing conditions can still be found if one asks for this condition to be satisfied only approximately. Such less restrictive conditions include a particular member of the 1+log family, which in the past has been found empirically to be extremely robust for both Brill wave and black hole simulations.Comment: 11 pages, revtex4. Change in acknowledgment

School Readiness: Implications for Policy

Includes bibliographical references.To prepare children for success in school, policies must provide support for all the contexts that influence child development starting from birth, and must seek to optimize children's functioning across all domains of development. This paper outlines a variety of factors affecting school readiness

Rural Child Care in Missouri: How to Improve it

Includes bibliographical references.During 1997 and 1998, a large study called Project REACH (Rural EArly CHildhood Professional Development Initiative), was conducted in a series of interventions over a 16 month period in rural Missouri. The training and follow up was intensive, continuous and individualized. An overview of the results are provided

Accurate Evolutions of Orbiting Binary Black Holes

We present a detailed analysis of binary black hole evolutions in the last orbit and demonstrate consistent and convergent results for the trajectories of the individual bodies. The gauge choice can significantly affect the overall accuracy of the evolution. It is possible to reconcile certain gauge-dependent discrepancies by examining the convergence limit. We illustrate these results using an initial data set recently evolved by Brügmann et al. [Phys. Rev. Lett. 92, 211101 (2004)]. For our highest resolution and most accurate gauge, we estimate the duration of this data set's last orbit to be approximately 59MADM

The State of Children and Families: 2009

This report contains information on current trends in the United States in areas including poverty, violence and crimes, unwed and teen pregnancy, education, nutrition, child health, child welfare, and housing

The State of Missouri's Children: 2009

Includes bibliographical references.A variety of problems affect the children of Missouri. The report contains details in categories including poverty, nutrition, education, health and welfare, substance abuse, teen pregnancy, and violence

The State of Child Welfare in America: 2009

In terms of physical and emotional suffering, an estimated 905,000 children were determined to be victims of child abuse or neglect in 2006 according to the U.S. Department of Health and Human Services. From the fiscal perspective, Prevent Child Abuse America has estimated that child abuse and neglect in the U.S. costs over $284 million dollars per day. This report also includes statistics on adoption and foster care

The State of Early Childhood Programs: 2009

Enriching experiences in the context of high quality early childhood programs give young children an enhanced chance at success in school. Poor children, who are particularly at risk for academic failure, can benefit greatly from early childhood programs that include not only education but other wide-ranging services for themselves and their families. Benefits of high quality early childhood experiences have been found to extend far beyond the young years, as they include a marked decrease in the likelihood children will some day engage in criminal activity or be dependent on public welfare programs

Entropic force in black hole binaries and its Newtonian limits

We give an exact solution for the static force between two black holes at the turning points in their binary motion. The results are derived by Gibbs' principle and the Bekenstein-Hawking entropy applied to the apparent horizon surfaces in time-symmetric initial data. New power laws are derived for the entropy jump in mergers, while Newton's law is shown to derive from a new adiabatic variational principle for the Hilbert action in the presence of apparent horizon surfaces. In this approach, entropy is strictly monotonic such that gravity is attractive for all separations including mergers, and the Bekenstein entropy bound is satisfied also at arbitrarily large separations, where gravity reduces to Newton's law. The latter is generalized to point particles in the Newtonian limit by application of Gibbs' principle to world-lines crossing light cones.Comment: Accepted for publication in Phys. Rev.