Probing the interiors of the ice giants: Shock compression of water to 700 GPa and 3.8 g/ccm

Recently there has been tremendous increase in the number of identified extra-solar planetary systems. Our understanding of their formation is tied to exoplanet internal structure models, which rely upon equations of state of light elements and compounds like water. Here we present shock compression data for water with unprecedented accuracy that shows water equations of state commonly used in planetary modeling significantly overestimate the compressibility at conditions relevant to planetary interiors. Furthermore, we show its behavior at these conditions, including reflectivity and isentropic response, is well described by a recent first-principles based equation of state. These findings advocate this water model be used as the standard for modeling Neptune, Uranus, and "hot Neptune" exoplanets, and should improve our understanding of these types of planets.Comment: Accepted to Phys. Rev. Lett.; supplementary material attached including 2 figures and 2 tables; to view attachments, please download and extract the gzipped tar source file listed under "Other formats

Role of accounting practices in the disempowerment of the Coahuiltecan Indians

This paper argues that a complex of accounting measures : account books, inventories of accumulated wealth, and detailed instructions for production performance : were used to inculcate Western values into the native population located at five Franciscan missions along the San Antonio River in New Spain (present-day Texas) from 1718 to 1794. Bolstered by the need to alleviate communications problems caused by extreme isolation, the missionaries constructed detailed mission documents that described the acquisition of scarce resources, reported the aggregation of material and spiritual mission wealth, and controlled daily production performance of the native population. In short, the resulting mission economic system, which held the Indians to certain notions of accountability, primarily by restricting their choices, nourished the Western view of income distribution based on effort. We propose that these procedures ultimately caused the Coahuiltecans to abandon their native beliefs, and gradually, to be absorbed into Spanish society. The 150 Coahuiltecan tribes ceased to exist as a distinct culture by the early 19th century. The exploitation and ultimate subjugation of the Coahuiltecan Indians parallels strikingly subsequent developments in Canada, Australia, and the Scottish Highlands

Large-Volume Neutron Counters with Subnanosecond Time Dispersions

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

High-Spin States in Nuclei Excited Via (p,n) Reactions

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

Performance of Large-Volume Mean-Timed Neutron Detectors

Supported by the National Science Foundation and Indiana Universit

High-Spin States and Spin-Coupled Quadrupole Vibrational States in Nuclei Excited Via (p,n) Reactions

This work was supported by National Science Foundation Grant PHY 76-84033 and Indiana Universit

A review of tennis racket performance parameters

The application of advanced engineering to tennis racket design has influenced the nature of the sport. As a result, the International Tennis Federation has established rules to limit performance, with the aim of protecting the nature of the game. This paper illustrates how changes to the racket affect the player-racket system. The review integrates engineering and biomechanical issues related to tennis racket performance, covering the biomechanical characteristics of tennis strokes, tennis racket performance, the effect of racket parameters on ball rebound and biomechanical interactions. Racket properties influence the rebound of the ball. Ball rebound speed increases with frame stiffness and as string tension decreases. Reducing inter-string contacting forces increases rebound topspin. Historical trends and predictive modelling indicate swingweights of around 0.030–0.035 kg/m2 are best for high ball speed and accuracy. To fully understand the effect of their design changes, engineers should use impact conditions in their experiments, or models, which reflect those of actual tennis strokes. Sports engineers, therefore, benefit from working closely with biomechanists to ensure realistic impact conditions

Differential cross sections for pion charge exchange on the proton at 27.5 MeV

We have measured pion single charge exchange differential cross sections on the proton at 27.5 MeV incident $\pi^-$ kinetic energy in the center of momentum angular range between $0^\circ$ and $55^\circ$. The extracted cross sections are compared with predictions of the standard pion-nucleon partial wave analysis and found to be in excellent agreement.Comment: ReVTeX v3.0 with aps.sty, 23 pages in e-print format, 7 PostScript Figures and 4 Tables, also available via anonymous ftp at ftp://helena.phys.virginia.edu/pub/preprints/scx.p

High-Spin States in Nuclei Excited Via the (p,n) Reactions

Supported by the National Science Foundation and Indiana Universit

Accumulation of driver and passenger mutations during tumor progression

Major efforts to sequence cancer genomes are now occurring throughout the world. Though the emerging data from these studies are illuminating, their reconciliation with epidemiologic and clinical observations poses a major challenge. In the current study, we provide a novel mathematical model that begins to address this challenge. We model tumors as a discrete time branching process that starts with a single driver mutation and proceeds as each new driver mutation leads to a slightly increased rate of clonal expansion. Using the model, we observe tremendous variation in the rate of tumor development - providing an understanding of the heterogeneity in tumor sizes and development times that have been observed by epidemiologists and clinicians. Furthermore, the model provides a simple formula for the number of driver mutations as a function of the total number of mutations in the tumor. Finally, when applied to recent experimental data, the model allows us to calculate, for the first time, the actual selective advantage provided by typical somatic mutations in human tumors in situ. This selective advantage is surprisingly small, 0.005 +- 0.0005, and has major implications for experimental cancer research