Positive curvature and the elliptic genus

We prove several results about the vanishing of the elliptic genus on positively curved Spin manifolds with logarithmic symmetry rank. The proofs are based on the rigidity of the elliptic genus and Kennard's improvement of the Connectedness Lemma for transversely intersecting, totally geodesic submanifolds.Comment: 15 pages. Paper was rewritten. To appear in New York Journal of Mathematic

X-Ray Polarimetry: Historical Remarks and Other Considerations

We briefly discuss the history of X-ray polarimetry for astronomical applications including a guide to the appropriate statistics. We also provide an introduction to some of the new techniques discussed in more detail elsewhere in these proceedings. We conclude our discussion with our concerns over adequate ground calibration, especially with respect to unpolarized beams, and at the system level.Comment: 8 pages, 1 figure presented at "The Coming of Age if X-ray Polarimetry", Rome, Italy April 27, 200

New Results from an old Friend: The Crab Nebula and its Pulsar

We summarize here the results, most of which are preliminary, of a number of recent observations of the Crab nebula system with the Chandra X-Ray Observatory. We discuss four different topics: (1) The motion on long (> 1yr) time scales of the southern jet. (2) The discovery that pulsar is not at the center of the projected ring on the sky and that the ring may well lie on the axis of symmetry but appears to be displaced at a latitude of about 5 degrees. (Note that this deprojection is by no means unique.) (3) The results and puzzling implications of the Chandra phase-resolved spectroscopy of the pulsar when compared to observations of pulse-phase variations of similar and dissimilar measures in other regions of the spectrum. (4) The search for the X-ray location of the site of the recently-discovered gamma-ray flaring. We also comment briefly on our plan to use the Chandra data we obtained for the previous project to study the nature of the low-energy flux variations recently detected at hard X-ray energies.Comment: 6 pages, 5 figures, submitted to the proceedings of the conference: "The Extreme and Variable High Energy Sky", 19-23 September 2011, Chia Laguna (Cagliari) - Ital

The Making of the Chandra X-ray Observatory: the Project Scientist's Perspective

We review the history of the development of the Chandra X-ray Observatory from our personal perspective. This review is necessarily biased and limited by space since it attempts to cover a time span approaching 5 decades.Comment: 6 pages, 17 figures. To be published in the Proceedings of the national Academy of Sciences of the United States of America

Monitor proportional counter

An Uhuru class Ar-CO2 gas filled proportional counter sealed with a 1.5 mil beryllium window and sensitive to X-rays in the energy bandwidth from 1.5 to 22 keV is presented. This device is coaligned with the X-ray telescope aboard the Einstein Observatory and takes data as a normal part of the Observatory operations

Inclusive CP Asymmetries in Semileptonic Decays of B Mesons

We estimate the sensitivity of single lepton CP violation measurements with respect to that of traditional di-lepton measurements. We find that the sensitivity of the single lepton method is better than that of the di-lepton method. The achievable sensitivity with the currently available data is already in the range relevant to standard model predictions. We also give general expressions for inclusive decay time distributions on $\Upsilon 4S$ where the other $B$ is not measured, which will be used to obtain time dependent asymmetries. The expression is of general use whenever one deals with inclusive time-dependent as well as time-integrated measurements in $\Upsilon(4S)\to B^0\bar B^0$ where the final state of the other $B$ is not reconstructed or when only the time difference is measured.Comment: 7 pages, 1 figure. Two references added, and a few typos correcte