Paper Session I-B - Preparing for Planetary Defense: Detection and Interception of Asteroids on Collision Course with Earth

Development of this system would benefit from the experience gained by the Air Force Space Command in its space surveillance mission for man-made Earth orbiting satellites, which in turn would benefit from technology developed for detection and tracking of asteroids. After such a system is in operation and has completed the initial catalogue, most large objects headed toward Earth could be detected years or even decades in advance, ample time to take action against them

Statistical multi-moment bifurcations in random delay coupled swarms

We study the effects of discrete, randomly distributed time delays on the dynamics of a coupled system of self-propelling particles. Bifurcation analysis on a mean field approximation of the system reveals that the system possesses patterns with certain universal characteristics that depend on distinguished moments of the time delay distribution. Specifically, we show both theoretically and numerically that although bifurcations of simple patterns, such as translations, change stability only as a function of the first moment of the time delay distribution, more complex patterns arising from Hopf bifurcations depend on all of the moments

Harold Jeffreys's Theory of Probability Revisited

Published exactly seventy years ago, Jeffreys's Theory of Probability (1939) has had a unique impact on the Bayesian community and is now considered to be one of the main classics in Bayesian Statistics as well as the initiator of the objective Bayes school. In particular, its advances on the derivation of noninformative priors as well as on the scaling of Bayes factors have had a lasting impact on the field. However, the book reflects the characteristics of the time, especially in terms of mathematical rigor. In this paper we point out the fundamental aspects of this reference work, especially the thorough coverage of testing problems and the construction of both estimation and testing noninformative priors based on functional divergences. Our major aim here is to help modern readers in navigating in this difficult text and in concentrating on passages that are still relevant today.Comment: This paper commented in: [arXiv:1001.2967], [arXiv:1001.2968], [arXiv:1001.2970], [arXiv:1001.2975], [arXiv:1001.2985], [arXiv:1001.3073]. Rejoinder in [arXiv:0909.1008]. Published in at http://dx.doi.org/10.1214/09-STS284 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Advances on Matroid Secretary Problems: Free Order Model and Laminar Case

The most well-known conjecture in the context of matroid secretary problems claims the existence of a constant-factor approximation applicable to any matroid. Whereas this conjecture remains open, modified forms of it were shown to be true, when assuming that the assignment of weights to the secretaries is not adversarial but uniformly random (Soto [SODA 2011], Oveis Gharan and Vondr\'ak [ESA 2011]). However, so far, there was no variant of the matroid secretary problem with adversarial weight assignment for which a constant-factor approximation was found. We address this point by presenting a 9-approximation for the \emph{free order model}, a model suggested shortly after the introduction of the matroid secretary problem, and for which no constant-factor approximation was known so far. The free order model is a relaxed version of the original matroid secretary problem, with the only difference that one can choose the order in which secretaries are interviewed. Furthermore, we consider the classical matroid secretary problem for the special case of laminar matroids. Only recently, a constant-factor approximation has been found for this case, using a clever but rather involved method and analysis (Im and Wang, [SODA 2011]) that leads to a 16000/3-approximation. This is arguably the most involved special case of the matroid secretary problem for which a constant-factor approximation is known. We present a considerably simpler and stronger $3\sqrt{3}e\approx 14.12$-approximation, based on reducing the problem to a matroid secretary problem on a partition matroid

Fatigue cracking in gamma titanium aluminide

Fatigue crack initiation and growth were examined in cast and HIP'ed \textgamma-TiAl 4522XD. It was found that fatigue crack growth rates were higher at 750\celsius than 400\celsius, but that $\Delta K_\mathrm{th}$ was also higher. Temperature excursions between $400$ and 750\celsius during fatigue crack growth resulted in retardation of the crack growth rate, both on heating and cooling; however heating from 400 to 750\celsius at a $\Delta K$ that would then be below threshold did not result in complete crack arrest. It was also found that for notches $0.6$~mm in length and smaller, initiation from the microstructure could instead be observed at stresses similar to the material failure stress; a microstructural initiation site exists. Secondary cracking around borides could also be observed. A change from trans- to mixed trans-, inter- and intra-lamellar cracking could be observed where the estimated size of the crack tip plastic zone exceeded the colony size. Changes in fracture surface morphology could not be related to the temperature of fatigue crack growth, although this could be observed from the oxide scale colouration. Compressive pre-loading of a crack results in retardation of the crack, which could also be observed from the oxide

Ceruloplasmin revisited: structural and functional roles of various metal cation-binding sites

The three-dimensional molecular structure of human serum ceruloplasmin has been reinvestigated using X-ray synchrotron data collected at 100 K from a crystal frozen to liquid-nitrogen temperature

Wind characteristics over complex terrain: laboratory simulation and field measurements at Rakaia Gorge, New Zealand: final report, part II

CER77-78RNM29.Prepared for the United States Department of Energy, Division of Solar Technology, Federal Wind Energy Program.DOE contract no. EY-76-S06-2438, A001.Includes bibliographical references (pages 93-102).May 1978

A fourth account of centipede (Chilopoda) predation on bats

With an incident in Palo Duro Canyon, Texas, USA, Scolopendra heros Girard (Chilopoda: Scolopendromorpha: Scolopendridae) becomes the third centipede species known to prey on bats; S. gigantea Linnaeus and S. viridicornis Newport have been so documented in Venezuela and Brazil, respectively. The Texas predation was interrupted by the predator/prey pair’s falling around 15–20 m from the canyon wall and, perhaps also, by human presence where they landed. The centipede uncoiled and retreated to shelter under a nearby rock and, after initial immobilization, so did the bat. Con un incidente en Palo Duro Canyon, Texas, Estados Unidos, Scolopendra heros Girard (Chilopoda: Scolopendromorpha: Scolopendridae) se convierte en el tercer ciempiés que se sabe depreda murciélagos; S. gigantea Linnaeus y S. viridicornis Newport han sido documentados mostrando este comportamiento en Venezuela y Brasil, respectivamente. El incidente de Texas fue interrumpido por el despeñamiento del par depredador/presa unos 15–20 m desde la pared del cañón y, al parecer, por la presencia humana en el sitio de caída. El ciempiés se desenrolló y retiró para refugiarse bajo una roca cercana. Tras permanecer inmóvil inicialmente, el murciélago hizo lo mismo