Infrared Period-Luminosity Relations of Evolved Variable Stars in the Large Magellanic Cloud

We combine variability information from the MAssive Compact Halo Objects (MACHO) survey of the Large Magellanic Cloud (LMC) with infrared photometry from the Spitzer Space Telescope Surveying the Agents of a Galaxy's Evolution (SAGE) survey to create a dataset of ~30 000 variable red sources. We photometrically classify these sources as being on the first ascent of the Red Giant Branch (RGB), or as being in one of three stages along the Asymptotic Giant Branch (AGB): oxygen-rich, carbon-rich, or highly reddened with indeterminate chemistry ("extreme" AGB candidates). We present linear period-luminosity relationships for these sources using 8 separate infrared bands (J, H, K, 3.6, 4.5, 5.8, 8.0, and 24 micron) as proxies for the luminosity. We find that the wavelength dependence of the slope of the period-luminosity relationship is different for different photometrically determined classes of AGB stars. Stars photometrically classified as O-rich show the least variation of slope with wavelength, while dust enshrouded extreme AGB stars show a pronounced trend toward steeper slopes with increasing wavelength. We find that O-rich AGB stars pulsating in the fundamental mode obey a period-magnitude relation with a slope of -3.41 +/- 0.04 when magnitude is measured in the 3.6 micron band, in contrast to C-rich AGB stars, which obey a relation of slope -3.77 +/- 0.05

Evidence for mass ejection associated with long secondary periods in red giants

Approximately 30% of luminous red giants exhibit a Long Secondary Period (LSP) of variation in their light curves, in addition to a shorter primary period of oscillation. The cause of the LSP has so far defied explanation: leading possibilities are binarity and a nonradial mode of oscillation. Here, large samples of red giants in the Large Magellanic Cloud both with and without LSPs are examined for evidence of an 8 or 24 $\mu$m mid-IR excess caused by circumstellar dust. It is found that stars with LSPs show a significant mid-IR excess compared to stars without LSPs. Furthermore, the near-IR $J$-$K$ color seems unaffected by the presence of the 24 $\mu$m excess. These findings indicate that LSPs cause mass ejection from red giants and that the lost mass and circumstellar dust is most likely in either a clumpy or a disk-like configuration. The underlying cause of the LSP and the mass ejection remains unknown.Comment: 6 pages, accepted for publication in Ap

Eccentric Ellipsoidal Red Giant Binaries in the LMC: Complete Orbital Solutions and Comments on Interaction at Periastron

Modelling ellipsoidal variables with known distances can lead to exact determination of the masses of both components, even in the absence of eclipses. We present such modelling using light and radial velocity curves of ellipsoidal red giant binaries in the LMC, where they are also known as sequence E stars. Stars were selected as likely eccentric systems on the basis of light curve shape alone. We have confirmed their eccentric nature and obtained system parameters using the Wilson-Devinney code. Most stars in our sample exhibit unequal light maxima as well as minima, a phenomenon not observed in sequence E variables with circular orbits. We find evidence that the shape of the red giant changes throughout the orbit due to the high eccentricity and the varying influence of the companion. Brief intervals of pulsation are apparent in two of the red giants. We determine pulsation modes and comment on their placement in the period-luminosity plane. Defining the parameters of these systems paves the way for modelling to determine by what mechanism eccentricity is maintained in evolved binaries.Comment: 14 pages, 11 figures. Accepted to MNRAS 2012 January

Soft-tissue specimens from pre-European extinct birds of New Zealand

We provide the first complete review of soft tissue remains from New Zealand birds that became extinct prior to European settlement (c. AD 1800). These rare specimens allow insights into the anatomy and appearance of the birds that are not attainable from bones. Our review includes previously unpublished records of ‘lost’ specimens, and descriptions of recently discovered specimens such as the first evidence of soft tissues from the South Island goose (Cnemiornis calcitrans). Overall, the soft tissue remains are dominated by moa (with specimens from each of the six genera), but also include specimens from Finsch's duck (Chenonetta finschi) and the New Zealand owlet-nightjar (Aegotheles novaezealandiae). All desiccated soft tissue specimens that have radiocarbon or stratigraphic dates are late Holocene in age, and most have been found in the semi-arid region of Central Otago

Acoustic oscillations in stars near the tip of the red giant branch

Small amplitude oscillations are observed in red giant branch (RGB) stars. Data on such oscillations are a source of information about the objects, notably about properties of convection in their envelopes and about the systems these objects inhabit. The OGLE-III catalog contains data for about 80 thousand small amplitude variable red giants (OSARGs) in the Large Magellanic Cloud. We want to explain variability in OSARGs as the solar-like oscillation and to associate the peaks in power spectra with frequencies of acoustic modes. We use data on reddening-free magnitudes of the objects and interpret them in terms of stellar physical parameters using tabulated isochrones calculated for ages and composition parameters corresponding to the upper RGB of the LMC. Massive data on the peak frequencies and amplitudes are compared with expectations for stochastically excited oscillations. The frequencies are also compared with those calculated for radial modes in envelope models with parameters taken from the isochrones. In stars close to the tip of the RGB, the peaks in power spectra are found in the 0.1-1.0 $\mu$Hz range, which is consistent with extrapolation of the frequency-luminosity relation for the solar-like oscillation. The dominant peaks occur close to the first two radial overtones. The increase in amplitude with luminosity is slower than linear. The exponent s=0.9 is similar to what is found from recent analysis of CoRoT data on less luminous red giants. Frequency separations between dominant peaks are found to be smaller by about 20% than calculated separations between these modes. After examining various possibilities, we left this discrepancy unexplained. The small amplitude variability of stars at the RGB tip is likely to be caused by a stochastic excitation of acoustic oscillations, but interpreting of individual peaks in power spectra presents a problem.Comment: Accepted for publication in Astronomy and Astrophysics, 6 pages, 6 figure

Radar studies of the vertical distribution of insects migrating over southern Britain: the influence of temperature inversions on nocturnal layer concentrations

Insects migrating over two sites in southern UK (Malvern in Worcestershire, and Harpenden in Hertfordshire) have been monitored continuously with nutating vertical-looking radars (VLRs) equipped with powerful control and analysis software. These observations make possible, for the first time, a systematic investigation of the vertical distribution of insect aerial density in the atmosphere, over temporal scales ranging from the short (instantaneous vertical profiles updated every 15 min) to the very long (profiles aggregated over whole seasons or even years). In the present paper, an outline is given of some general features of insect stratification as revealed by the radars, followed by a description of occasions during warm nights in the summer months when intense insect layers developed. Some of these nocturnal layers were due to the insects flying preferentially at the top of strong surface temperature inversions, and in other cases, layering was associated with higher-altitude temperature maxima, such as those due to subsidence inversions. The layers were formed from insects of a great variety of sizes, but peaks in the mass distributions pointed to a preponderance of medium-sized noctuid moths on certain occasions

A central line care maintenance bundle for the prevention of central line–associated bloodstream infection in non–intensive care unit settings

OBJECTIVE: To evaluate a central line care maintenance bundle to reduce central line-associated bloodstream infection (CLABSI) in non-ICU settings. DESIGN: Before-after trial with 12 month follow-up period. SETTING: 1250-bed teaching hospital. PARTICIPANTS: Patients with central lines on eight general medicine wards. Four wards received the intervention and four served as controls. INTERVENTION: A multifaceted catheter care maintenance bundle consisting of educational programs for nurses, update of hospital policies, visual aids, a competency assessment, process monitoring, regular progress reports, and consolidation of supplies necessary for catheter maintenance. RESULTS: Data were collected for 25,542 catheter-days including 43 CLABSI (rate = 1.68 per 1,000 CL-days) and 4,012 catheter dressing observations. Following the intervention, a 2.5% monthly decrease in the CLABSI incidence density was observed on intervention floors, but this was not statistically significant (95% confidence interval (CI); −5.3 – 0.4). On control floors, there was a smaller, but marginally significant decrease in CLABSI incidence during the study (change in monthly rate = −1.1%; 95% CI, −2.1 - −0.1). Implementation of the bundle was associated with improvement in catheter dressing compliance on intervention wards (78.8% compliance pre-intervention vs. 87.9% during intervention/follow-up; p<0.001) but improvement was also observed on control wards (84.9% compliance pre-intervention vs. 90.9% during intervention/follow-up; P = .001). CONCLUSIONS: A multi-faceted program to improve catheter care was associated with improvement in catheter dressing care, but no change in CLABSI rates. Additional study is needed to determine strategies to prevent CLABSI in non-ICU patients

MicroRNA-155 regulates monocyte chemokine and chemokine receptor expression in Rheumatoid Arthritis

Objectives: To test the hypothesis that miR-155 regulates monocyte migratory potential via modulation of chemokine and chemokine receptor expression in rheumatoid arthritis (RA); and thereby is associated with disease activity. Methods: miR-155 copy-number in monocytes from peripheral blood (PB) of healthy (n=22), RA (n=24), and RA synovial fluid (SF; n=11) were assessed by real time- PCR using synthetic miR-155 as quantitative standard. To evaluate the functional impact of miR-155, human monocytes were transfected with control or miR-155 mimic and the effect on transcript levels, and production of chemokines was evaluated by TLDA and multiplex assays. A comparative study evaluated constitutive chemokine receptor expression in miR-155-/- and wild-type murine (CD115+Ly6C+Ly6G-) monocytes. Results: Compared with healthy monocytes, miR-155 copy-number was higher in RA PB and SF monocytes (PB p&lt;0.01, and SF p&lt;0.0001). MiR-155 copy-number in RA PB monocytes were higher in ACPA positive compared with ACPA negative patients (p=0.033) and correlated (95% C.I.) with DAS28 (ESR), R=0.728 (0.460, 0.874), with tender, R=0.631 (0.306, 0.824) and swollen, R=0.503 (0.125, 0.753) joint counts. Enforced-expression of miR-155 in RA monocytes stimulated the production of CCL3, CCL4, CCL5, CCL8; up-regulated CCR7 expression and down-regulated CCR2. Conversely, miR155-/- monocytes showed down-regulated CCR7 and upregulated CCR2 expression. Conclusions: Given the observed correlations with disease activity, these data provide strong evidence that miR-155 can contribute to RA pathogenesis by regulating chemokine production and pro-inflammatory chemokine receptor expression, thereby promoting inflammatory cell recruitment and retention in the RA synovium

Period-Magnitude relation of Mira-like variables in the Large Magellanic Cloud as a tool to understand circumstellar extinction

Near- to mid-infrared period-magnitude relations and also the period-bolometric luminosity relation of OGLE-III Mira-like variables in the LMC are derived. The relations have a kink, and the period at which the break occurs is quantitatively obtained. There are many Mira-like variables whose fluxes at the optical and the near-infrared wavebands are fainter than the ones predicted by the period-magnitude relations. The deviation is due to the circumstellar extinction, and the amount of the deviation is found to be strongly correlated with near-infrared colors. The empirical formulae relating the amount of the deviation and the near-infrared colors are derived. These relations are useful to accurately calculate the distances to the dusty Mira-like variables, because the dimmed fluxes due to the circumstellar extinction can be estimated. In a manner analogous to the interstellar extinction law, the ratios of deviations at any two different wavebands are calculated. The ratios are found to change with the pulsation period, indicating that the dust properties are subject to change as Mira-like variables evolve.Comment: 8 pages, 5 figures and 4 tables, accepted for publication in MNRA