New floristic data of alien vascular plants from Sicily

New records of Commelina communis, Euphorbia hypericifolia, Melia azedarach, Nicotiana tabacum, and Xanthoceras sorbifolium are reported for the Sicilian flora

Perceptions of a guided wilderness trail

Personal recorded Interviews with past and present guides of the Wilderness Leadership School were used to identify four Important factors in a successful guided wilderness trail. Using postal questionnaires, guides and members of the Wilderness Leadership School were asked to rank nine trail scenarios. The technique of conjoint analysis yielded the relative importance, as perceived by the guides and trialists, of each of the four factors. It was shown that the most important attribute for both groups of respondents was how the trails interacted with one another. Next in importance was an increase in awareness, by the trialists of the if interdependence environment. This was followed by the personality of the guide and finally signs of modern man's impact in the wilderness area. There was an important difference in percept f on between the guides and the trails; the trails firsts placed more emphasis on the group interact ion and wilderness on an increase in awareness. There were also differences in perception between the different category of guides and trail fists. of' activities and related experiences relative to a successful trail are included in the report

Providing Equitable Access to Education for African American Students: The Journey of One Administrative Team

This study explored the journey of one administrative team in a Midwestern suburban high school in their efforts to provide equitable access to education for African American students. It examined the high school administrative processes, and the perceived impacts of these processes in identifying, addressing and removing the institutional barriers to academic success for African American students. I focused on an initiative developed by members of this administrative team that is an intervention designed specifically for African American students and articulated as such. As both an insider to this school’s administrative team and a veteran administrator, and as an outsider to the design of this intervention, I used grounded theory to develop administrative models for other administrators working to even the playing field for all students. By deconstruction of this initiative through in-depth interviews and observations, I mapped the varied successes and challenges encountered in administrative processes

Simulating CCD images of elliptical galaxies

We introduce a procedure developed by the ``Teramo Stellar Populations Tools'' group (Teramo-SPoT), specifically optimized to obtain realistic simulations of CCD images of elliptical galaxies. Particular attention is devoted to include the Surface Brightness Fluctuation (SBF) signal observed in ellipticals and to simulate the Globular Cluster (GC) system in the galaxy, and the distribution of background galaxies present in real CCD frames. In addition to the physical properties of the simulated objects - galaxy distance and brightness profile, luminosity function of GC and background galaxies, etc. - the tool presented allows the user to set some of the main instrumental properties - FoV, zero point magnitude, exposure time, etc.Comment: Presented at From Stars to Galaxies: Building the Pieces to Build up the Universe (StarGal 2006), Venice, Italy, 16-20 Oct 200

Detection of Surface Brightness Fluctuations in Elliptical Galaxies imaged with the Advanced Camera for Surveys. B- and I-band measurements

Taking advantage of the exceptional capabilities of ACS on board of HST, we derive Surface Brightness Fluctuation (SBF) measurements in the B and I bands from images of six elliptical galaxies with $1500 \leq cz \leq 3500$. Given the low S/N ratio of the SBF signal in the blue band images, the reliability of the measurements is verified both with numerical simulations and experimental data tests. This paper presents the first published B- and I-band SBF measurements for distant ($\geq$ 20 Mpc) galaxies, essential for the comparisons of the models to observations of normal ellipticals. By comparing I-band data with our new Simple Stellar Population (SSP) models we find an excellent agreement and we confirm that I-band SBF magnitudes are mainly sensitive to the metallicity of the dominant stellar component in the galaxy, and are not strongly affected by the contribution of possible secondary stellar components. As a consequence I-band fluctuations magnitudes are ideal for distance studies. On the other hand, we show that standard SSP models do not reproduce the B-band SBF magnitudes of red ((B-I)_0 \gsim 2.1) galaxies in our sample. We explore the capability of two non--canonical models in properly reproducing the high sensitivity of B SBF to the presence of even small fractions of bright, hot stars (metal poor stars, hot evolved stars, etc.). The disagreement is solved both by taking into account hot (Post--AGB) stars in SSP models and/or by adopting Composite Stellar Population models. Finally, we suggest a limit value of the S/N for the B-band SBF signal required to carry out a detailed study of stellar population properties based on this technique.Comment: ApJ accepte

Spectral libraries and their uncertainties

Libraries of stellar spectra are fundamental tools in the study of stellar populations and in automatic determination of atmospheric parameters for large samples of observed stars. In the context of the present volume, here I give an overview of the current status of stellar spectral libraries from the perspective of stellar population modeling: what we have currently available, how good they are, and where we need further improvement

New Aloes casual aliens in Sicily

Aloë arborescens, A. brachystachys and A. maculata (Asphodelaceae) are reported for the first time as casual aliens in Sicily. A. brachystachys is new also for the alien flora of Italy

The Next Generation Virgo Cluster Survey (NGVS). XVIII. Measurement and Calibration of Surface Brightness Fluctuation Distances for Bright Galaxies in Virgo (and Beyond)

We describe a program to measure surface brightness fluctuation (SBF) distances to galaxies observed in the Next Generation Virgo Cluster Survey (NGVS), a photometric imaging survey covering $104~deg^2$ of the Virgo cluster in the ${u}^*,g,i,z$ bandpasses with the Canada-France Hawaii Telescope. We describe the selection of the sample galaxies, the procedures for measuring the apparent $i$-band SBF magnitude $\bar{i}$, and the calibration of the absolute $\bar{M}_i$ as a function of observed stellar population properties. The multi-band NGVS data set provides multiple options for calibrating the SBF distances, and we explore various calibrations involving individual color indices as well as combinations of two different colors. Within the color range of the present sample, the two-color calibrations do not significantly improve the scatter with respect to wide-baseline, single-color calibrations involving $u^{*}$. We adopt the ${u}^*{-}z$ calibration as reference for the present galaxy sample, with an observed scatter of 0.11 mag. For a few cases that lack good ${u}^*$ photometry, we use an alternative relation based on a combination of $g{-}i$ and $g{-}z$ colors, with only a slightly larger observed scatter of 0.12 mag. The agreement of our measurements with the best existing distance estimates provides confidence that our measurements are accurate. We present a preliminary catalog of distances for 89 galaxies brighter than $B_T\approx13.0$ mag within the survey footprint, including members of the background M and W Clouds at roughly twice the distance of the main body of the Virgo cluster. The extension of the present work to fainter and bluer galaxies is in progress.Comment: ApJ accepte

Water vapour permeability of clay bricks

The water vapour permeability of clay bricks has been experimentally measured in order to draw a representative outline of industrial products without pore-forming additives. The correlations between water vapour permeability and the main compositional and microstructural parameters of both bricks and clay bodies have been investigated. A statistical model was set up in order to predict with reasonable precision and reliability, the water vapour permeability on the basis of open porosity, bulk density, mean pore size and pore specific surface values of bricks, and the finer particle size of clay bodies