Interstellar Krypton Abundances: The Detection of Kiloparsec-scale Differences in Galactic Nucleosynthetic History

We present an analysis of Kr I 1236 line measurements from 50 sight lines in the Hubble Space Telescope Space Telescope Imaging Spectrograph and Goddard High Resolution Spectrograph data archives that have sufficiently high resolution and signal-to-noise ratio to permit reliable krypton-to-hydrogen abundance ratio determinations. The distribution of Kr/H ratios in this sample is consistent with a single value for the ISM within 5900 pc of the Sun, log(Kr/H) = -9.02+/-0.02, apart from a rough annulus from between about 600 and 2500 pc distant. The Kr/H ratio toward stars within this annulus is elevated by approximately 0.11 dex, similar to previously noted elevations of O/H and Cu/H gas-phase abundances beyond about 800 pc. A significant drop in the gas-phase N/O ratio in the same region suggests that this is an artifact of nucleosynthetic history. Since the physical scale of the annulus' inner edge is comparable to the radius of the Gould Belt and the outer limit of heliocentric distances where the D/H abundance ratio is highly variable, these phenomena may be related to the Gould Belt's origins.Comment: 32 pages, including 6 figures; accepted by Ap

Interstellar Carbon in Translucent Sightlines

We report interstellar C II column densities or upper limits determined from weak absorption of the 2325.4029 A intersystem transition observed in six translucent sightlines with STIS. The sightlines sample a wide range of interstellar characteristics including total-to-selective extinction, R_{V} = 2.6 - 5.1; average hydrogen density along the sightline, = 3 - 14 cm^{-3}; and fraction of H in molecular form, 0 - 40%. Four of the sightlines, those toward HD 37021, HD 37061, HD 147888 and HD 207198, have interstellar gas-phase abundances that are consistent with the diffuse sightline ratio of 161 +/- 17 carbon atoms in the gas per million hydrogen nuclei. We note that while it has a gas-phase carbon abundance that is consistent with the other sightlines, a large fraction of the C II toward HD 37061 is in an excited state. The sightline toward HD 152590 has a measured interstellar gas-phase carbon abundance that is well above the diffuse sightline average; the column density of C in this sightline may be overestimated due to noise structure in the data. Toward HD 27778 we find a 3 sigma abundance upper limit of <108 C atoms in the gas per million H, a substantially enhanced depletion of C as compared to the diffuse sightline value. The interstellar characteristics toward HD 27778 are otherwise not extreme among the sample except for an unusually large abundance of CO molecules in the gas.Comment: Accepted for publication in the Astrophysical Journa

The Homogeneity of Interstellar Oxygen in the Galactic Disk

We present an analysis of high resolution HST Space Telescope Imaging Spectrograph (STIS) observations of O I 1356 and H I Lyman-alpha absorption in 36 sight lines that probe a variety of Galactic disk environments and include paths that range over nearly 4 orders of magnitude in f(H_2), over 2 orders of magnitude in mean sight line density, and that extend up to 6.5 kpc in length. Consequently, we have undertaken the study of gas-phase O/H abundance ratio homogeneity using the current sample and previously published Goddard High-Resolution Spectrograph (GHRS) results. Two distinct trends are identified in the 56 sight line sample: an apparent decrease in gas-phase oxygen abundance with increasing mean sight line density and a gap between the mean O/H ratio for sight lines shorter and longer than about 800 pc. The first effect is a smooth transition between two depletion levels associated with large mean density intervals; it is centered near a density of 1.5 cm^-3 and is similar to trends evident in gas-phase abundances of other elements. Paths less dense than the central value exhibit a mean O/H ratio of log_10 (O/H) = -3.41+/-0.01 (or 390+/-10 ppm), which is consistent with averages determined for several long, low-density paths observed by STIS (Andre et al. 2003) and short low-density paths observed by FUSE (Moos et al. 2002). Sight lines of higher mean density exhibit an average O/H value of log_10 (O/H) = -3.55+/-0.02 (284+/-12 ppm). The datapoints for low-density paths are scattered more widely than those for denser sight lines, due to O/H ratios for paths shorter than 800 pc that are generally about 0.10 dex lower than the values for longer ones.Comment: 33 pages, including 8 figures and 4 tables; accepted for publication in ApJ, tentatively in Oct 200

FUSE Measurements of Far Ultraviolet Extinction. I. Galactic Sight Lines

We present extinction curves that include data down to far ultraviolet wavelengths (FUV; 1050 - 1200 A) for nine Galactic sight lines. The FUV extinction was measured using data from the Far Ultraviolet Spectroscopic Explorer. The sight lines were chosen for their unusual extinction properties in the infrared through the ultraviolet; that they probe a wide range of dust environments is evidenced by the large spread in their measured ratios of total-to-selective extinction, R_V = 2.43 - 3.81. We find that extrapolation of the Fitzpatrick & Massa relationship from the ultraviolet appears to be a good predictor of the FUV extinction behavior. We find that predictions of the FUV extinction based upon the Cardelli, Clayton & Mathis (CCM) dependence on R_V give mixed results. For the seven extinction curves well represented by CCM in the infrared through ultraviolet, the FUV extinction is well predicted in three sight lines, over-predicted in two sight lines, and under-predicted in 2 sight lines. A Maximum Entropy Method analysis using a simple three component grain model shows that seven of the nine sight lines in the study require a larger fraction of grain materials to be in dust when FUV extinction is included in the models. Most of the added grain material is in the form of small (radii < 200 A) grains.Comment: Accepted for publication in the Astrophysical Journal. 31 pages with 7 figure

Cardiomyocyte Ca2+ handling and structure is regulated by degree and duration of mechanical load variation

Cardiac transverse (t)-tubules are altered during disease and may be regulated by stretch-sensitive molecules. The relationship between variations in the degree and duration of load and t-tubule structure remains unknown, as well as its implications for local Ca2+-induced Ca2+ release (CICR). Rat hearts were studied after 4 or 8 weeks of moderate mechanical unloading [using heterotopic abdominal heart–lung trans-plantation (HAHLT)] and 6 or 10 weeks of pressure overloading using thoracic aortic constriction. CICR, cell and t-tubule structure were assessed using confocal-microscopy, patch-clamping and scanning ion conductance microscopy. Moderate unloading was compared with severe unloading [using heart-only transplantation (HAHT)]. Mechanical unloading reduced cardiomyocyte volume in a time-dependent manner. Ca2+ release synchronicity was reduced at 8 weeks moderate unloading only. Ca2+ sparks increased in frequency and duration at 8 weeks of moderate unloading, which also induced t-tubule disorganization. Overloading increased cardiomyocyte volume and disrupted t-tubule mor-phology at 10 weeks but not 6 weeks. Moderate mechanical unloading for 4 weeks had milder effects compared with severe mechanical unloading (37 % reduction in cell volume at 4 weeks compared to 56 % reduction after severe mechanical unloading) and did not cause depres-sion and delay of the Ca2+ transient, increased Ca2+ spark frequency or impaired t-tubule and cell surface structure. These data suggest that variations in chronic mechanical load influence local CICR and t-tubule structure in a time- and degree-dependent manner, and that physiologi-cal states of increased and reduced cell size, without pathological changes are possible

Incidence of Post-ablation Syndrome Following Image-Guided Percutaneous Cryoablation of Renal Cell Carcinoma: A Prospective Study

Purpose: To prospectively evaluate the incidence of post-ablation syndrome (fever and flu-like symptoms) and impact on the quality of life in the first 10 days following percutaneous image-guided cryoablation for renal cell carcinoma (RCC). Materials and Methods: A prospective study of all cryoablation procedures with biopsy proven RCC was conducted with institutional review board approval between 08/2012 and 04/2016. Sixty-four patients (43 males and 21 females) underwent cryoablation. Mean age was 68 (range 24–86). A telephone questionnaire survey was conducted on days 1, 3, 5, 7 and 10 following cryoablation, and complications were recorded. Data collected included temperature, degree of flu-like symptoms, severity of pain, percentage of pain relief with analgesics, interference with general activity and with work (graded on a 0–10 Numeric Intensity Scale). Results: Following cryoablation, six patients (9%) out of 64 developed post-ablation syndrome. Thirty-three patients (52%) developed flu-like symptoms only, which completely resolved by day 10 in 25 patients (39%). One patient had pyrexia only, which was self- limiting by day 10. Twenty-four patients (38%) were asymptomatic. Pain (mean score = 2.1) and interference on general activities (mean score = 1.8) and work (mean score = 2) following cryoablation peaked on day 3 and improved subsequently. Forty-six patients (72%) had 90–100% pain relief by day 10. No major complications were observed. Conclusion: The full spectrum of post-ablation syndrome following cryoablation occurs in approximately 9% of patients; however, 61% of patients experience flu-like symptoms in the first 10 days, which are self-limiting

Origin and evolution of the light nuclides

After a short historical (and highly subjective) introduction to the field, I discuss our current understanding of the origin and evolution of the light nuclides D, He-3, He-4, Li-6, Li-7, Be-9, B-10 and B-11. Despite considerable observational and theoretical progress, important uncertainties still persist for each and every one of those nuclides. The present-day abundance of D in the local interstellar medium is currently uncertain, making it difficult to infer the recent chemical evolution of the solar neighborhood. To account for the observed quasi-constancy of He-3 abundance from the Big Bang to our days, the stellar production of that nuclide must be negligible; however, the scarce observations of its abundance in planetary nebulae seem to contradict this idea. The observed Be and B evolution as primaries suggests that the source composition of cosmic rays has remained quasi-constant since the early days of the Galaxy, a suggestion with far reaching implications for the origin of cosmic rays; however, the main idea proposed to account for that constancy, namely that superbubbles are at the source of cosmic rays, encounters some serious difficulties. The best explanation for the mismatch between primordial Li and the observed "Spite-plateau" in halo stars appears to be depletion of Li in stellar envelopes, by some yet poorly understood mechanism. But this explanation impacts on the level of the recently discovered early ``Li-6 plateau'', which (if confirmed), seriously challenges current ideas of cosmic ray nucleosynthesis.Comment: 18 pages, 9 figs. Invited Review in "Symposium on the Composition of Matter", honoring Johannes Geiss on the occasion of his 80th birthday (Grindelwald, Switzerland, Sept. 2006), to be published in Space Science Series of ISS

Short-term psychosocial outcomes of adding a non-contrast abdominal computed tomography (CT) scan to the thoracic CT within lung cancer screening.

OBJECTIVES: To evaluate psychological, social, and financial outcomes amongst individuals undergoing a non-contrast abdominal computed tomography (CT) scan to screen for kidney cancer and other abdominal malignancies alongside the thoracic CT within lung cancer screening. SUBJECTS AND METHODS: The Yorkshire Kidney Screening Trial (YKST) is a feasibility study of adding a non-contrast abdominal CT scan to the thoracic CT within lung cancer screening. A total of 500 participants within the YKST, comprising all who had an abnormal CT scan and a random sample of one-third of those with a normal scan between 14/03/2022 and 24/08/2022 were sent a questionnaire at 3 and 6 months. Outcomes included the Psychological Consequences Questionnaire (PCQ), the short-form of the Spielberger State-Trait Anxiety Inventory, and the EuroQoL five Dimensions five Levels scale (EQ-5D-5L). Data were analysed using regression adjusting for participant age, sex, socioeconomic status, education, baseline quality of life (EQ-5D-5L), and ethnicity. RESULTS: A total of 380 (76%) participants returned questionnaires at 3 months and 328 (66%) at 6 months. There was no difference in any outcomes between participants with a normal scan and those with abnormal scans requiring no further action. Individuals requiring initial further investigations or referral had higher scores on the negative PCQ than those with normal scans at 3 months (standardised mean difference 0.28 sd, 95% confidence interval 0.01-0.54; P = 0.044). The difference was greater in those with anxiety or depression at baseline. No differences were seen at 6 months. CONCLUSION: Screening for kidney cancer and other abdominal malignancies using abdominal CT alongside the thoracic CT within lung cancer screening is unlikely to cause significant lasting psychosocial or financial harm to participants with incidental findings

Properties and Origin of the High-Velocity Gas Toward the Large Magellanic Cloud

In the spectra of 139 early-type Large Magellanic Cloud (LMC) stars observed with FUSE and with deep radio Parkes HI 21-cm observations along those stars, we search for and analyze the absorption and emission from high-velocity gas at +90<v<+175 km/s. The HI column density of the high-velocity clouds (HVCs) along these sightlines ranges from <10^18.4 to 10^19.2 cm^-2. The incidence of the HVC metal absorption is 70%, significantly higher than the HI emission occurrence of 32%. We find that the mean metallicity of the HVC is [OI/HI] = -0.51 (+0.12,-0.16). There is no strong evidence for a large variation in the HVC metallicity, implying that thes e HVCs have a similar origin and are part of the same complex. The mean and scatter of the HVC metallicities are more consistent with the present-day LMC oxygen abundance than that of the Small Magellanic Cloud or the Milky Way. We find that on average [SiII/OI] = +0.48 (+0.15,- 0.25) and [FeII/OI] = +0.33 (+0.14,-0.21), implying that the HVC complex is dominantly ionized. The HVC complex has a multiphase structure with a neutral (OI, FeII), weakly ionized (FeII, NII), and highly ionized (OVI) components, and has evidence of dust but no molecules. All the observed properties of the HVC can be explained by an energetic outflow from the LMC. This is the first example of a large (>10^6 M_sun) HVC complex that is linked to stellar feedback occurring in a dwarf spiral galaxy.Comment: Accepted for publication in the Ap

The Boundary Conditions of the Heliosphere: Photoionization Models Constrained by Interstellar and In Situ Data

The boundary conditions of the heliosphere are set by the ionization, density and composition of inflowing interstellar matter. Constraining the properties of the Local Interstellar Cloud (LIC) at the heliosphere requires radiative transfer ionization models. We model the background interstellar radiation field using observed stellar FUV and EUV emission and the diffuse soft X-ray background. We also model the emission from the boundary between the LIC and the hot Local Bubble (LB) plasma, assuming that the cloud is evaporating because of thermal conduction. We create a grid of models covering a plausible range of LIC and LB properties, and use the modeled radiation field as input to radiative transfer/thermal equilibrium calculations using the Cloudy code. Data from in situ observations of He^O, pickup ions and anomalous cosmic rays in the heliosphere, and absorption line measurements towards epsilon CMa were used to constrain the input parameters. A restricted range of assumed LIC HI column densities and LB plasma temperatures produce models that match all the observational constraints. The relative weakness of the constraints on N(HI) and T_h contrast with the narrow limits predicted for the H^O and electron density in the LIC at the Sun, n(H^0) = 0.19 - 0.20 cm^-3, and n(e) = 0.07 +/- 0.01 cm^-3. Derived abundances are mostly typical for low density gas, with sub-solar Mg, Si and Fe, possibly subsolar O and N, and S about solar; however C is supersolar. The interstellar gas at the Sun is warm, low density, and partially ionized, with n(H) = 0.23 - 0.27 cm^-3, T = 6300 K, X(H^+) ~ 0.2, and X(He^+) ~ 0.4. These results appear to be robust since acceptable models are found for substantially different input radiation fields. Our results favor low values for the reference solar abundances for the LIC composition.Comment: 14 pages, 4 figures, submitted to Astronomy & Astrophysics together with papers from the International Space Sciences Institute workshop on Interstellar Hydrogen in the Heliospher