Deep HST V- and I-Band Observations of Two Globular Clusters in the Halo of M31

We present deep (V ~= 27) V- and I-band stellar photometry of G302 and G312, two globular star clusters in the halo of M31. These data were obtained using the Hubble Space Telescope's Wide Field/Planetary Camera 2. We find iron abundances of [Fe/H] = -1.85 +/- 0.12 for G302 and [Fe/H] = -0.56 +/- 0.03 for G312, consistent with spectroscopic measurements. The color-magnitude diagrams for each cluster show no evidence for an intermediate-aged population of stars, or a second parameter effect in the morphology of the horizontal branch. G302 shows no evidence for a color gradient but the inner regions of G312 are bluer than the outer regions. G312 shows no evidence of ellipticity or an extended halo of unbound stars. G302 has a projected ellipticity of 0.195 +/- 0.012 with the projected major axis oriented towards the center of M31. G302 also shows evidence of an extended asymmetric stellar halo extending to at least twice the fitted Michie-King tidal radius. The amount of mass beyond the tidal radius of G302 is consistent with the stellar escape rates which have been predicted by N-body simulations of globular clusters in the Galactic tidal field.Comment: 29 pages, 21 Postscript figures, uses aaspp4.sty, to be published in the October 1997 A

The Double Cluster G185 in M31

We have identified a small globular cluster in M31 located approximately 4 arcseconds northwest of the M31 globular cluster G185. While several multiple globular clusters have been observed in the Magellanic Clouds none have been found in the Galaxy or in M31. We estimate the probability of such a chance line-of-sight alignment occuring near the nucleus of M31 to be 0.09 +/- 0.03 and find no obvious indication of any tidal deformation in either cluster, as would be expected if the clusters were interacting. Two-dimensional modelling suggests G185 has a King (1966) [AJ, 71, 64] concentration of c = 1.11 +/- 0.08 while the companion has c = 0.67 +/- 0.17 and is physically smaller than G185. Both objects have integrated dereddened colors similar to those of Galactic globular clusters.Comment: 22 pages, ~1Mb postscript file http://www.astro.ubc.ca/~holland/bib.html/ ftp://nukta.astro.ubc.ca/pub/holland/G185_preprint.ps.

Reaction of nitric oxide and its derivatives with sulfites: A possible role in sulfite toxicity

AbstractThe reaction between sulfites and nitric oxide or proposed carriers of nitric oxide (nitrosylated bovine serum albumin and S-nitrosoglutathione) was investigated as a potential source of the adverse effects of sulfites on biological systems. Rapid reaction occurred between sulfites and all of these reagents. Also, the ability of nitric oxide and these carriers of nitric oxide to inhibit platelet aggregation was reversed by low concentrations of sulfites. Counteraction of nitric oxide's ability to function in cell signaling processes may be a major cause of sulfite toxicity

Deep HST V- and I-Band Observations of the Halo of M31: Evidence for Multiple Stellar Populations

We present deep V & I WFPC2 photometry in two fields in the M31 halo 32' and 50' from the center of M31 along the SE minor axis at the locations of the M31 GCs G302 and G312 respectively. The M31 halo LFs are not consistent with a single high-metallicity population but are consistent with a mix of 50% to 75% metal-rich stars and 25% to 50% metal-poor stars. This agrees with the RGB morphology, the HB luminosity, and the RR Lyrae stars in the M31 halo. The RGB morphology indicates a metallicity spread of -2 < [m/H] < -0.2 with most stars having [m/H] = -0.6, making the M31 halo significantly more metal- rich than either the Galactic halo or the M31 GC system. The HB is dominated by a red clump similar to the 47 Tuc HB but a small number of blue HB stars are visible, supporting the conclusion that there is a metal-poor component to the M31 halo. The number of HB stars is smaller than would be expected from the observed metallicity distribution but it is not clear if this is due to the photometric limits of our data or a 2nd parameter effect. We find a He abundance of Y >~ 0.20 to 0.27, comparable with the Galaxy. LFs show weak evidence that the R = 50' field contains a higher fraction of metal-poor stars than the R = 32' field but the metallicity distributions of the RGB stars strongly suggest that both fields have the same mix of stellar populations.Comment: 31 pages AASTeX v4.0, 10 Figures avaliable at ftp://ftp.astro.ubc.ca/holland/M31_hal

Incremental Prognostic Value of Echocardiographic Strain and Its Association with Mortality in Cancer Patients

Background Left ventricular global longitudinal systolic strain (GLS) has been shown to be superior to ejection fraction in detecting subclinical dysfunction in patients with cancer and predicting mortality in patients with cardiovascular disease. Cancer-related fatigue is common in the later stages of neoplastic malignancies and may be indicative of nonovert heart failure. The aim of this study was to determine whether reduced strain by echocardiography was associated with all-cause mortality in a cancer cohort. Methods In this retrospective study, 120 patients with cancer undergoing or scheduled to undergo chemotherapy and with normal ejection fractions (>50%) underwent assessments of GLS. GLS was derived by averaging all speckle-tracking strain segments of the left ventricle. Results Over an average follow-up period of 21.6 ± 13.9 months, 57 of 120 patients died. Univariate predictors of all-cause mortality (P < .10) were Eastern Cooperative Oncology Group performance status, male sex, hematologic malignancy, β-blocker use, and GLS. Multivariate analysis of all significant univariate variables showed that Eastern Cooperative Oncology Group performance status (hazard ratio, 2.12; 95% confidence interval, 1.54–2.92; P < .001), male sex (hazard ratio, 1.93; 95% confidence interval, 1.14–3.27; P = .014), and GLS (hazard ratio, 0.89; 95% confidence interval, 0.81–0.97; P = .012) were significantly and independently associated with mortality. Stepwise analysis of the multivariate associations showed an increase in the global χ2 value after adding GLS (P = .011) to significant clinical variables. Conclusions Eastern Cooperative Oncology Group performance status, male sex, and GLS were significantly associated with all-cause mortality in patients with cancer with normal ejection fractions receiving chemotherapy. Adding GLS to significant clinical variables provided incremental prognostic information

Measuring Entangled Qutrits and Their Use for Quantum Bit Commitment

We produce and holographically measure entangled qudits encoded in transverse spatial modes of single photons. With the novel use of a quantum state tomography method that only requires two-state superpositions, we achieve the most complete characterisation of entangled qutrits to date. Ideally, entangled qutrits provide better security than qubits in quantum bit-commitment: we model the sensitivity of this to mixture and show experimentally and theoretically that qutrits with even a small amount of decoherence cannot offer increased security over qubits.Comment: Paper updated to match published version; 5 pages, 4 figures, images have been included at slightly lower quality for the archiv

A Young White Dwarf Companion to Pulsar 1620-26: Evidence for Early Planet Formation

The pulsar B1620-26 has two companions, one of stellar mass and one of planetary mass. We detected the stellar companion using Hubble Space Telescope observations. The color and magnitude of the stellar companion indicate that it is an undermassive white dwarf ($0.34 \pm 0.04 M_{\odot}$) of age $480\pm 140$ Myr. This places a constraint on the recent history of this triple system and supports a scenario in which the current configuration arose through a dynamical exchange interaction in the cluster core. This implies that planets may be relatively common in low-metallicity globular clusters and that planet formation is more widespread and happened earlier than previously believed.Comment: 4 pages, published in Scienc

Prognostic utility of blood pressure-adjusted global and basal systolic longitudinal strain

Assessment of global longitudinal systolic strain (GLS) and longitudinal systolic strain of the basal segments (BLS) has shown prognostic value in cardiac disorders. However, strain is reduced with increased afterload. We assessed the prognostic value of GLS and BLS adjusted for afterload. GLS and BLS were determined in 272 subjects with normal ejection fraction and no known coronary disease, or significant valve disease. Systolic blood pressure (SP) and diastolic blood pressure (DP) obtained at the time of echocardiography were used to adjust GLS and BLS as follows: strain×SP (mmHg)/120 mmHg and strain×DP (mmHg)/80 mmHg. Patients were followed for cardiac events and mortality. The mean age was 53±15 years and 53% had hypertension. There were 19 cardiac events and 70 deaths over a mean follow-up of 26±14 months. Cox analysis showed that left ventricular mass index (P=0.001), BLS (P<0.001), and DP-adjusted BLS (P<0.001) were independent predictors of cardiac events. DP-adjusted BLS added incremental value (P<0.001) to the other two predictors and had an area under the curve of 0.838 for events. DP (P=0.001), age (P=0.001), ACE inhibitor use (P=0.017), and SP-adjusted BLS (P=0.012) were independent predictors of mortality. SP-adjusted BLS added incremental value (P=0.014) to the other independent predictors. In conclusion, DP-adjusted BLS and SP-adjusted BLS were independent predictors of cardiac events and mortality, respectively. Blood pressure-adjusted strain added incremental prognostic value to other predictors of outcome