612 research outputs found

    On the Globular Cluster IMF below 1 Solar Mass

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    (Abridged) Accurate luminosity functions (LF) for a dozen globular clusters have now been measured at or just beyond their half-light radius using HST. They span almost the entire cluster main sequence below ~ 0.75 Msolar. All these clusters exhibit LF that rise continuously from an absolute I magnitude M_I ~ 6 to a peak at M_I ~ 8.5-9 and then drop with increasing M_I. Transformation of the LF into mass functions (MF) by means of the most recent mass luminosity relations that are consistent with all presently available data on the physical properties of low mass, low metallicity stars shows that all the LF observed so far can be obtained from MF having the shape of a log-normal distribution with characteristic mass m_c=0.33 +/- 0.03 Msolar and standard deviation sigma = 1.81 +/- 0.19. After correction for the effects of mass segregation, the variation of the ratio of the number of higher to lower mass stars with cluster mass or any simple orbital parameter or the expected time to disruption recently computed for these clusters shows no statistically significant trend over a range of this last parameter of more than a factor of 100. We conclude that the global MF of these clusters have not been measurably modified by evaporation and tidal interactions with the Galaxy and, thus, should reflect the initial distribution of stellar masses. Since the log-normal function that we find is also very similar to the one obtained independently for much younger clusters and to the form expected theoretically, the implication seems to be unavoidable that it represents the true stellar IMF for this type of stars in this mass range.Comment: Accepted for publication in The Astrophysical Journal. Contains 28 pages with 6 figure

    Some observations on the relationship of manifest and hidden esca to rainfall

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    This paper reports observations on the relationship between the yearly incidence of manifest esca (i.e. diseased plants which show foliar symptoms), hidden esca (that which remains asymptomatic throughout a growing season) and rainfall. Data from three vineyards (two in Tuscany and one in Emilia-Romagna, Italy) showed that rainfall in May-July or only in July was inversely related with hidden esca. For two vineyards, TB in Emilia-Romagna and CAR-3 in Tuscany, the spatial pattern of diseased vines in the first year of appearance of the foliar esca symp-toms was also determined. The maps of the vines in these vineyards indicated that diseased plants mostly occurred alone. This suggests that the disease had its origin in infected rooted cuttings or was triggered by inoculum aerially dispersed from distant sources and/or occurring, at least in hypothesis, in the soil

    Prediction of protein composition of individual cow milk using mid-infrared spectroscopy.

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    This study investigated the application of mid-infrared spectroscopy for the prediction of protein composition in individual milk samples (n=1,336) of Simmental cows. Protein fractions were quantified by RP-HPLC and MIR data were recorded over the spectral range from 4,000 to 900 cm-1. Models were developed by partial least squares regression using untreated spectra. The most successful predictions were for protein, casein, αS1-casein, whey protein, and β-lactoglobulin contents. The models could discriminate between high and low values of protein composition (R2=0.50 to 0.58). The root mean square errors of cross-validation were 3.11g/l for protein (range 39.91g/l), 2.76g/l for casein (range 35.16g/l), 1.07 g/l for αS1-casein (range 12.82g/l), 0.51 g/l for whey protein (range 4.97g/l), and 0.43 for β-lactoglobulin (range 4.37). Application of MIR spectroscopy is possible for the routinely assessment of protein, casein, αS1-casein, whey protein, and β-lactoglobulin and its implementation might be in future a tool for improving protein composition of bovine milk through breeding programs

    The radio science experiment with BepiColombo mission to Mercury

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    BepiColombo is a joint ESA/JAXA mission to Mercury with challenging objectives regarding geophysics, geodesy and fundamental physics. The Mercury Orbiter Radio science Experiment (MORE) is one of the on-board experiments, including three different but linked experiments: gravimetry, rotation and relativity. Using radio observables (range and range-rate) performed with very accurate tracking from ground stations, together with optical observations from the on-board high resolution camera (SIMBIO-SYS) and accelerometer readings from the on-board accelerometer (ISA), MORE will be able to measure with unprecedented accuracy the global gravity field of Mercury and the rotation state of the planet. In this work we present the results of a numerical full-cycle simulation of the gravimetry and rotation experiments of MORE: we discuss the accuracies which can be achieved, focussing in particular on the possible benefits from the use of optical observations in support to the tracking measurements

    Star Formation in the Starburst Cluster in NGC 3603

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    We have used new, deep, visible and near infrared observations of the compact starburst cluster in the giant HII region NGC 3603 and its surroundings with the WFC3 on HST and HAWK-I on the VLT to study in detail the physical properties of its intermediate mass (~ 1 - 3 M_sun) stellar population. We show that after correction for differential extinction and actively accreting stars, and the study of field star contamination, strong evidence remains for a continuous spread in the ages of pre-main sequence stars in the range ~ 2 to ~ 30 Myr within the temporal resolution available. Existing differences among presently available theoretical models account for the largest possible variation in shape of the measured age histograms within these limits. We also find that this isochronal age spread in the near infrared and visible Colour-Magnitude Diagrams cannot be reproduced by any other presently known source of astrophysical or instrumental scatter that could mimic the luminosity spread seen in our observations except, possibly, episodic accretion. The measured age spread and the stellar spatial distribution in the cluster are consistent with the hypothesis that star formation started at least 20-30 Myrs ago progressing slowly but continuously up to at least a few million years ago. All the stars in the considered mass range are distributed in a flattened oblate spheroidal pattern with the major axis oriented in an approximate South-East - North-West direction, and with the length of the equatorial axis decreasing with increasing age. This asymmetry is most likely due to the fact that star formation occurred along a filament of gas and dust in the natal molecular cloud oriented locally in this direction.Comment: 21 pages, 19 figures, accepted for publication in Astrophysics & Space Scienc

    Sporotrichoid Mycobacterium marinum infection in an elderly woman

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    We describe the case of an elderly woman who acquired a Mycobacterium marinum infection following skin exposure to the bacteria through a small wound on her right ring finger, obtained while preparing fish. The resultant sporotrichoid nodules of the right hand and the distal forearm, refractory to the initial therapy with doxycycline and rifampicin, were successfully treated with oral regimen of clarithromycin. \ua9 2015 by the article author(s)

    Deep Photometry of the Globular Cluster M5: Distance Estimates from White Dwarf and Main Sequence Stars

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    We present deep VI photometry of stars in the globular cluster M5 (NGC 5904) based on images taken with the Hubble Space Telescope. The resulting color-magnitude diagram reaches below V ~ 27 mag, revealing the upper 2-3 magnitudes of the white dwarf cooling sequence, and main sequence stars eight magnitudes and more below the turn-off. We fit the main sequence to subdwarfs of known parallax to obtain a true distance modulus of (m-M)_0 = 14.45 +/- 0.11 mag. A second distance estimate based on fitting the cluster white dwarf sequence to field white dwarfs with known parallax yielded (m-M)_0 = 14.67 +/- 0.18 mag. We couple our distance estimates with extensive photometry of the cluster's RR Lyrae variables to provide a calibration of the RR Lyrae absolute magnitude yielding M_V(RR) = 0.42 +/- 0.10 mag at [Fe/H] = -1.11 dex. We provide another luminosity calibration in the form of reddening-free Wasenheit functions. Comparison of our calibrations with predictions based on recent models combining stellar evolution and pulsation theories shows encouraging agreement. (Abridged)Comment: AASTeX, 29 pages including 5 figures. Complete photometry data and FITS-format images are available at http://physics.bgsu.edu/~layden/ASTRO/PUBL/published.html . Accepted for publication in the Astrophysical Journal, 2005 October 20. Replaced errant wording in last sentence of paragraph 4 of conclusion

    The effects of an extra U(1) axial condensate on the radiative decay eta' --> gamma gamma at finite temperature

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    Supported by recent lattice results, we consider a scenario in which a U(1)-breaking condensate survives across the chiral transition in QCD. This scenario has important consequences on the pseudoscalar-meson sector, which can be studied using an effective Lagrangian model. In particular, generalizing the results obtained in a previous paper (where the zero-temperature case was considered), we study the effects of this U(1) chiral condensate on the radiative decay eta' --> gamma gamma at finite temperature.Comment: 15 pages, LaTeX fil

    Some Observations on the Relationship of Manifest and Hidden Esca to Rainfall

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    This paper reports observations on the relationship between the yearly incidence of manifest esca (i.e. diseased plants which show foliar symptoms), hidden esca (that which remains asymptomatic throughout a growing season) and rainfall. Data from three vineyards (two in Tuscany and one in Emilia-Romagna, Italy) showed that rainfall in May–July or only in July was inversely related with hidden esca. For two vineyards, TB in Emilia-Romagna and CAR-3 in Tuscany, the spatial pattern of diseased vines in the first year of appearance of the foliar esca symptoms was also determined. The maps of the vines in these vineyards indicated that diseased plants mostly occurred alone. This suggests that the disease had its origin in infected rooted cuttings or was triggered by inoculum aerially dispersed from distant sources and/or occurring, at least in hypothesis, in the soil
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