Discovery of hot supergiant stars near the Galactic center

We report new results of a campaign to find Wolf-Rayet and O (WR/O) stars and high-mass X-ray binaries (HMXBs) in the Galactic center. We searched for candidates by cross-correlating the 2MASS catalog with a deep Chandra catalog of X-ray point sources in the Radio Arches region. Following up with K-band spectroscopy, we found two massive stellar counterparts to CXOGC J174555.3-285126 and CXOGC J174617.0-285131, which we classify as a broad-lined WR star of sub-type WN6b and an O Ia supergiant, respectively. Their X-ray properties are most consistent with those of known colliding-wind binaries in the Galaxy and the Large Magellanic Cloud, although a scenario involving low-rate accretion onto a compact object is also possible. The O Ia star lies 4.4 pc in projection from the Quintuplet cluster, and has a radial velocity consistent with that of the Quintuplet, suggesting that this star might have escaped from the cluster. We also present the discovery of a B2 Ia supergiant, which we identified as a candidate massive star using 8 micron Spitzer maps of the Galactic center in a region near the known massive X-ray-emitting star CXOGC J174516.1-290315. We discuss the origin of these stars in the context of evolving stellar clusters in the Galactic center.Comment: 21 pages, 5 figures, accepted for publication in the Astrophysical Journa

Extended treatment with MY-NEOVAX, personalized neoantigen-enhanced oncolytic viruses, for two end-stage cancer patients.

Neoantigen vaccines involving multi-peptides and poly-epitope-encoding RNA or DNA have undergone early phase clinical testing with modest reported antitumor effects [ 1]. The less-than-expected activity of these neoantigenic vaccines may correspond with the development of immune escape mechanisms. One permutation on neoantigen vaccines, which may counter or prevent these adaptive immune escape mechanisms, are 'personalized' oncolytic viruses that encode one or more tumor-specific transgenes. Herein, positive therapeutic effects for MY-NEOVAX™, personalized neoantigen-enhanced oncolytic adenoviruses, are described for two heavily pretreated end-stage patients, one with high-grade metastatic neuroendocrine carcinoma of the pancreas and the other with colorectal cancer metastatic to the brain, liver and lungs. To date, treatment benefit has exceeded 12 months without dose-limiting toxicities or related serious adverse events and with documented radiologic stabilization and improved performance status

Anomaly Detection in Paleoclimate Records using Permutation Entropy

Permutation entropy techniques can be useful in identifying anomalies in paleoclimate data records, including noise, outliers, and post-processing issues. We demonstrate this using weighted and unweighted permutation entropy of water-isotope records in a deep polar ice core. In one region of these isotope records, our previous calculations revealed an abrupt change in the complexity of the traces: specifically, in the amount of new information that appeared at every time step. We conjectured that this effect was due to noise introduced by an older laboratory instrument. In this paper, we validate that conjecture by re-analyzing a section of the ice core using a more-advanced version of the laboratory instrument. The anomalous noise levels are absent from the permutation entropy traces of the new data. In other sections of the core, we show that permutation entropy techniques can be used to identify anomalies in the raw data that are not associated with climatic or glaciological processes, but rather effects occurring during field work, laboratory analysis, or data post-processing. These examples make it clear that permutation entropy is a useful forensic tool for identifying sections of data that require targeted re-analysis---and can even be useful in guiding that analysis.Comment: 15 pages, 7 figure

Near-Infrared Counterparts to Chandra X-ray Sources toward the Galactic Center. I. Statistics and a Catalog of Candidates

We present a catalog of 5184 candidate infrared counterparts to X-ray sources detected towards the Galactic center. The X-ray sample contains 9017 point sources detected in this region by the Chandra X-ray Observatory, including data from a recent deep survey of the central 2 x 0.8 deg of the Galactic plane. A total of 6760 of these sources have hard X-ray colors, and the majority of them lie near the Galactic center, while most of the remaining 2257 soft X-ray sources lie in the foreground. We cross-correlated the X-ray source positions with the 2MASS and SIRIUS near-infrared catalogs, which collectively contain stars with a 10-sigma limiting flux of K_s<=15.6 mag. In order to distinguish absorbed infrared sources near the Galactic center from those in the foreground, we defined red and blue sources as those which have H-K_s>=0.9 and <=0.9 mag, respectively. We find that 5.8(1.5)% of the hard X-ray sources have real infrared counterparts, of which 228(99) are red and 166(27) are blue. The red counterparts are probably comprised of WR/O stars, HMXBs, and symbiotics near the Galactic center. We also find that 39.4(1.0)% of the soft X-ray sources have blue infrared counterparts; most of these are probably coronally active dwarfs in the foreground. There is a noteworthy collection of ~20 red counterparts to hard X-ray sources near the Sagittarius-B H II region, which are probably massive binaries that have formed within the last several Myr. For each of the infrared matches to X-ray sources in our catalog we derived the probability that the association is real, based on the results of the cross-correlation analysis. The catalog will serve spectroscopic surveys to identify infrared counterparts to X-ray sources near the Galactic center.Comment: Submitted to ApJ January 16, 2009; accepted July 21, 2009; 30 pages, 6 figure

Porous silica spheres as indoor air pollutant scavengers

Porous silica spheres were investigated for their effectiveness in removing typical indoor air pollutants, such as aromatic and carbonyl-containing volatile organic compounds (VOCs), and compared to the commercially available polymer styrene-divinylbenzene (XAD-4). The silica spheres and the XAD-4 resin were coated on denuder sampling devices and their adsorption efficiencies for volatile organic compounds evaluated using an indoor air simulation chamber. Real indoor sampling was also undertaken to evaluate the affinity of the silica adsorbents for a variety of indoor VOCs. The silica sphere adsorbents were found to have a high affinity for polar carbonyls and found to be more efficient than the XAD-4 resin at adsorbing carbonyls in an indoor environment