An empirical calibration of Lick indices using Milky Way Globular Clusters

To provide an empirical calibration relation in order to convert Lick indices into abundances for the integrated light of old, simple stellar populations for a large range in the observed [Fe/H] and [alpha/Fe]. This calibration supersedes the previously adopted ones because it is be based on the real abundance pattern of the stars instead of the commonly adopted metallicity scale derived from the colours. We carried out a long-slit spectroscopic study of 23 Galactic globular cluster for which detailed chemical abundances in stars have been recently measured. The line-strength indices, as coded by the Lick system and by Serven et al. (2005), were measured in low-resolution integrated spectra of the GC light. The results were compared to average abundances and abundance ratios in stars taken from the compilation by Pritzl et al. (2005) as well as to synthetic models. Fe-related indices grow linearly as a function of [Fe/H] for [Fe/H]>-2. Mg-related indices respond in a similar way to [Mg/H] variations, however Mgb turns out to be a less reliable metallicity indicator for [Z/H]<-1.5 . Despite the known Mg overabundance with respect to Fe in GC stars, it proved impossible to infer a mean [Mg/Fe] for integrated spectra that correlates with the resolved stars properties, because the sensitivity of the indices to [Mg/Fe] is smaller at lower metallicities. We present empirical calibrations for Ca, TiO, Ba and Eu indices as well as the measurements of H_alpha and NaD.Comment: 16 pages, 15 figures, to appear on A&

A Library of Integrated Spectra of Galactic Globular Clusters

We present a new library of integrated spectra of 40 Galactic globular clusters, obtained with the Blanco 4-m telescope and the R-C spectrograph at the Cerro Tololo Interamerican Observatory. The spectra cover the range ~ 3350 -- 6430 A with ~ 3.1 A (FWHM) resolution. The spectroscopic observations and data reduction were designed to integrate the full projected area within the cluster core radii in order to properly sample the light from stars in all relevant evolutionary stages. The S/N values of the flux-calibrated spectra range from 50 to 240/A at 4000 A and from 125 to 500/A at 5000 A. The selected targets span a wide range of cluster parameters, including metallicity, horizontal-branch morphology, Galactic coordinates, Galactocentric distance, and concentration. The total sample is thus fairly representative of the entire Galactic globular cluster population and should be valuable for comparison with similar integrated spectra of unresolved stellar populations in remote systems. For most of the library clusters, our spectra can be coupled with deep color-magnitude diagrams and reliable metal abundances from the literature to enable the calibration of stellar population synthesis models. In this paper we present a detailed account of the observations and data reduction. The spectral library is publicly available in electronic format from the National Optical Astronomical Observatory website.Comment: 39 Pages, including 2 tables and 15 Figures. To appear in the Astrophysical Journal, Supplement Serie

A Substantial Population of Low Mass Stars in Luminous Elliptical Galaxies

The stellar initial mass function (IMF) describes the mass distribution of stars at the time of their formation and is of fundamental importance for many areas of astrophysics. The IMF is reasonably well constrained in the disk of the Milky Way but we have very little direct information on the form of the IMF in other galaxies and at earlier cosmic epochs. Here we investigate the stellar mass function in elliptical galaxies by measuring the strength of the Na I doublet and the Wing-Ford molecular FeH band in their spectra. These lines are strong in stars with masses <0.3 Msun and weak or absent in all other types of stars. We unambiguously detect both signatures, consistent with previous studies that were based on data of lower signal-to-noise ratio. The direct detection of the light of low mass stars implies that they are very abundant in elliptical galaxies, making up >80% of the total number of stars and contributing >60% of the total stellar mass. We infer that the IMF in massive star-forming galaxies in the early Universe produced many more low mass stars than the IMF in the Milky Way disk, and was probably slightly steeper than the Salpeter form in the mass range 0.1 - 1 Msun.Comment: To appear in Natur

The design of window shades and fenestration for view clarity

The ability to discern the content of the view through a window is referred to as view clarity. It is often overlooked in the design process, and the methods of shading daylight can affect window views. We conducted a narrative review of building standards and the scientific literature to better understand how shades can be designed so as to retain the window view. View clarity was characterised by three main dimensions: (1) the shading solution, (2) the view content and (3) the observer. Each dimension and the interactions between them influence view clarity. These interactions make it difficult to predict view clarity for all the situations that can occur in buildings. Nonetheless, we highlighted the effects of different shades on the view clarity. Our insights can help designers consider these impacts within the context of overall window design

Strigolactones affect phosphorus acquisition strategies in tomato plants

Strigolactones (SLs) are plant hormones that modulate morphological, physiological and biochemical changes as part of the acclimation strategies to phosphorus (P) deficiency, but an in‐depth description of their effects on tomato P‐acquisition strategies under P shortage is missing. Therefore, in this study, we investigate how SLs impact on root exudation and P uptake, in qualitative and quantitative terms over time, in wild‐type and SL‐depleted tomato plants grown with or without P. Under P shortage, SL‐depleted plants were unable to efficiently activate most mechanisms associated with the P starvation response (PSR), except for the up‐regulation of P transporters and increased activity of P‐solubilizing enzymes. The reduced SL biosynthesis had negative effects also under normal P provision, because plants over‐activated high‐affinity transporters and enzymatic activities (phytase, acidic phosphatase) to sustain elevated P uptake, at great carbon and nitrogen costs. A shift in the onset of PSR was also highlighted in these plants. We conclude that SLs are master kinetic regulators of the PSR in tomato and that their defective synthesis might lead both to suboptimal nutritional outcomes under P depletion and an unbalanced control of P uptake when P is available

Observations of T Tauri Disks at Sub-AU Radii: Implications for Magnetospheric Accretion and Planet Formation

We determine inner disk sizes and temperatures for four solar-type (1-2 M$_{\odot}$) classical T Tauri stars (AS 207A, V2508 Oph, AS 205A, and PX Vul) using 2.2 $\mu$m observations from the Keck Interferometer. Nearly contemporaneous near-IR adaptive optics imaging photometry, optical photometry, and high-dispersion optical spectroscopy are used to distinguish contributions from the inner disks and central stars in the interferometric observations. In addition, the spectroscopic and photometric data provide estimates of stellar properties, mass accretion rates, and disk co-rotation radii. We model our interferometric and photometric data in the context of geometrically flat accretion disk models with inner holes, and flared disks with puffed-up inner walls. Models incorporating puffed-up inner disk walls generally provide better fits to the data, similar to previous results for higher-mass Herbig Ae stars. Our measured inner disk sizes are larger than disk truncation radii predicted by magnetospheric accretion models, with larger discrepancies for sources with higher mass accretion rates. We suggest that our measured sizes correspond to dust sublimation radii, and that optically-thin gaseous material may extend further inward to the magnetospheric truncation radii. Finally, our inner disk measurements constrain the location of terrestrial planet formation as well as potential mechanisms for halting giant planet migration.Comment: Accepted for publication in ApJ (May 1, 2005 issue

Effect of decreasing dietary crude protein on growth performance, feed efficiency and meat quality of finishing Charolais bulls

This study aimed to evaluate the effect of decreasing dietary crude protein (CP) on the performance of finishing Charolais bulls in the Italian rearing system. Animals were fed two diets, differing only in the CP level (low protein (LP), 13.5% CP versus control (CON), 15.0% CP). Dry matter (DM) intake (DMI) and animals\u2019 weights were recorded to obtain average daily gain (ADG) and feed conversion rate (FCR). Feed and fecal samples were collected to evaluate digestibility of diet components. Daily cost of the ration (DRC), feed cost per kg of daily weight gain (CDG) and daily gross margin (DGM) were calculated to analyze the possible benefits of decreasing the protein level. Meat quality analyses were also conducted. Higher DMI (10.6 versus 10 kg/d; p < 0.05) and ADG (1.47 versus 1.36 kg/d; p < 0.05) were observed for CON. No differences in FCR or digestibility were found. Even if the DRC was lower (p < 0.05) for the LP diet (2.26 versus 1.97 \u20ac; CON versus LP), no difference was reported for CDG and DGM. Meat lightness and redness were significantly lower and higher in the LP, respectively. To conclude, the CP requirement in these rearing conditions appeared to be higher than 13.5%

Grain yeld of lima bean (phaseolus lunatus) genotypes from subtropical Brazil.

BIC

Near-infrared Spectral Features in Single-aged Stellar Populations

Synthetic spectra for single-aged stellar populations of metallicities [M/H] = -0.5, 0.0 and +0.5, ages = 3 to 17 Gyrs, and initial mass function exponents x = 0.1 to 2.0 were built in the wavelength range 6000-10200 Angstrons. For such we have employed the grid of synthetic spectra described in Schiavon & Barbuy (1999), computed for the stellar parameters 2500 <= Teff <= 6000 K, -0.5 <= log g <= 5.0, [M/H] = -0.5, 0.0 and +0.5, and [alpha/Fe] = 0.0, together with the isochrones by Bertelli et al. (1994) and Baraffe et al. (1998). The behavior of the features NaI8190, CaII8662, TiO6600 and FeH9900 in the integrated spectra of single stellar populations were studied in terms of metallicity, initial mass function and age variations. The main conclusions are that the NaI doublet is an IMF-sensitive feature, which is however sensitive also to metallicity and age, whereas TiO, CaII and FeH are very sensitive to metallicity and essentially insensitive to IMF and age.Comment: 13 pages + 7 figures, ApJ accepte

A multianalytical approach to investigate stone biodeterioration at a UNESCO world heritage site: the volcanic rock-hewn churches of Lalibela, Northern Ethiopia.

A multianalytical approach combining Optical Microscopy (OM), Backscattered Variable Pressure Scanning Electron Microscopy + Energy Dispersive X-ray Spectroscopy (VP-BSEM + EDS), Powder X-ray Diffractometry (PXRD), Raman Spectroscopy, and Microbiological techniques has been applied to characterize decay products and processes occurring at the surface of two rockhewn churches (Bete Gyorgis and Bete Amanuel) at the UNESCO’s World Heritage site of Lalibela, Northern Ethiopia. The two churches were carved into volcanic scoria deposits of basaltic composition. In their geological history, the Lalibela volcanic rocks underwent late to post-magmatic hydrothermal alteration together with partial laterization and are therefore characterized by a decay-prone highly vesicular microtexture with late stage to post-magmatic precipitation of secondary mineral phases (calcite–zeolite–smectite). The main objective of the study was to gain a better insight into the weathering products and mechanisms affecting the surface of the stone monuments and to assess the relative contribution of natural “geological” weathering processes versus biological/salt attack in stone decay at this unique heritage site. Results indicate that while the main cause of bulk rock deterioration and structural failure could be related to the stone inherited “geological” features, biological attack by micro- (bacteria) and/or macro- (lichens) organisms is currently responsible for severe stone surface physical and chemical weathering leading to significant weakening of the stone texture and to material loss at the surface of the churches walls. A prompt and careful removal of the biological patinas with the correct biocidal treatment is therefore recommended