The Different Environmental Dependencies of Star-formation for Giant and Dwarf Galaxies

We examine the origins of the bimodality observed in the global properties of galaxies around a stellar mass of 3x10^10 M_sun by comparing the environmental dependencies of star-formation for the giant and dwarf galaxy populations. The Sloan Digital Sky Survey DR4 spectroscopic dataset is used to produce a sample of galaxies in the vicinity of the supercluster centered on the cluster A2199 at z=0.03 that is ~90% complete to a magnitude limit of M*+3.3. From these we measure global trends with environment for both giant (M_r<-20 mag) and dwarf (-19<M_r<-17.8 mag) subsamples using the luminosity-weighted mean stellar age and H_alpha emission as independent measures of star-formation history. The fraction of giant galaxies classed as old (t>7 Gyr) or passive (EW[H_alpha]<4 A) falls gradually from ~80% in the cluster cores to ~40% in field regions beyond 3-4 R_virial, as found in previous studies. In contrast, we find that the dwarf galaxy population shows a sharp transition at ~1 R_virial, from being predominantly old/passive within the cluster, to outside where virtually all galaxies are forming stars and old/passive galaxies are only found as satellites to more massive galaxies. These results imply fundamental differences in the evolution of giant and dwarf galaxies: whereas the star-formation histories of giant galaxies are determined primarily by their merger history, star-formation in dwarf galaxies is much more resilient to the effects of major mergers. Instead dwarf galaxies become passive only once they become satellites within a more massive halo, by losing their halo gas reservoir to the host halo, or through other environment-related processes such as galaxy harassment and/or ram-pressure stripping.Comment: 4 pages, 4 figures, accepted for publication in ApJ

Natural zeolites and white wines from Campania region (Southern Italy): a new contribution for solving some oenological problems

The purpose of this research is to provide a new mixture of Campanian zeolitized tuffs for solving two specific problems in the production of white wines: the protein and tartaric stability. In fact, a very frequent cause of turbidity and formation of organic deposits in white wines is the occurrence of thermolabile and thermostable proteins colloidal suspensions which precipitate in time, especially in summertime and during the storage and transport. Normally, to mitigate this risk wine producers use organic and inorganic stabilizers and clarifiers. The best known treatment, recognized also by the International Organisation of Vine and Wine (OIV) foresees the use of bentonite with a montmorillonite content not lower than 80%. The present paper aims at evaluating the use of two high zeolite grade Italian volcanoclastites such as the Neapolitan Yellow Tuff (NYT) and the Yellow Facies of the Campanian Ignimbrite (YFCI), in the treatment of three peculiar white wines of the Campanian region (Southern Italy): Falanghina, Fiano di Avellino and Greco di Tufo. Granulates were produced starting from tuff blocks as provided by quarries. Some grain size fractions have been prepared to investigate the zeolite content (phillipsite + chabazite + analcime) by X-ray diffraction (XRD). A 2-5 mm grain size fraction was chosen for NYT and a 5-10 mm for YFCI. Three Campanian monocultivar white wines were used for the test: the Falanghina 2006 vintage, the Fiano di Avellino DOCG 2007 vintage, and the Greco di Tufo DOCG 2008 vintage. 48 samples with mixture of the zeolitized tuffs, 1 sample with mixture of a synthetic zeolite A and 1 sample with mixture of a commercial sodium activated bentonite were prepared. ICP-OES analysis for the determination of ECEC, Ion Chromatography (IC) analyses for the determination of some major cations and Turbidimetric tests for the definition of the protein stabilization process before and after treatments were also carried out. It was evidenced that high zeolitized tuff/wine ratios enable the protein stabilization whereas a significant decrease of potassium ion after the treatment with a zeolite-rich powder improves the tartaric stability, a serious problem in all the wine productions. The results of these tests refer to a laboratory scale research. A transfer of the experiment to a pilot plant scale is in progress

Dynamical Evolution and Galaxy Populations in the Cluster ABCG 209 at z=0.2

The thesis work is focused on the analysis of the galaxy clusters ABCG 209, at z~0.2, which is characterized by a strong dynamical evolution. The data sample used is based mainly on new optical data (EMMI-NTT: B, V and R band images and MOS spectra), acquired in October 2001 at the European Southern Observatory in Chile. Archive optical data (CFHR12k: B and R images), and X-ray (Chandra) and radio (VLA) observations are also analysed. The main goal of the present analysis is the investigation of the connection between internal cluster dynamics and star formation history, aimed at understanding the complex mechanisms of cluster formation and evolution. The analysis of the internal dynamics of the cluster and the study of the galaxy luminosity function (LF) suggest an observational scenario in which ABCG 209 is undergoing a strong dynamical evolution with the merging of two or more subclumps along the SE-NW direction in a plane which is not parallel to the plane of sky. The effect of cluster environment on the global properties of the cluster galaxies is examined through the analysis of the LFs, colour-magnitude relations, and average colours.Moreover cluster dynamics and large-scale structure have a strong influence on galaxy evolution, so it is performed a detailed study of spectroscopic properties of 102 luminous member galaxies. All the results support an evolutionary scenario in which ABCG 209 is characterized by a sum of two components: an old galaxy population, formed very earlier (z >~ 3), and a younger population of infalling galaxies. Moreover this cluster may have experimented 1 or 2 Gyrs ago a merging with an infalling galaxy group, as indicated also by the previous dynamical analysis.Comment: 212 pages, 44 figure, Ph.D. Thesis: University of Trieste. Fig. 2.14 and 4.1 are significantly de-graded due to the size limitatio

Structure and Evolution of Galaxy Clusters: Internal Dynamics of ABCG 209 at z~0.21

We study the internal dynamics of the rich galaxy cluster ABGC 209 on the basis of new spectroscopic and photometric data. The distribution in redshift shows that ABCG 209 is a well isolated peak of 112 detected member galaxies at z=0.209, characterised by a high value of the line-of-sight velocity dispersion, sigma_v=1250-1400 Km/s, on the whole observed area (1 Mpc/h from the cluster center), that leads to a virial mass of M=1.6-2.2x10^15 M_sun within the virial radius, assuming the dynamical equilibrium. The presence of a velocity gradient in the velocity field, the elongation in the spatial distribution of the colour-selected likely cluster members, the elongation of the X-ray contour levels in the Chandra image, and the elongation of cD galaxy show that ABCG 209 is characterised by a preferential NW-SE direction. We also find a significant deviation of the velocity distribution from a Gaussian, and relevant evidence of substructure and dynamical segregation. All these facts show that ABCG 209 is a strongly evolving cluster, possibly in an advanced phase of merging.Comment: 26 pages, 14 figures. A&A in pres

Photometric redshifts for Quasars in multi band Surveys

MLPQNA stands for Multi Layer Perceptron with Quasi Newton Algorithm and it is a machine learning method which can be used to cope with regression and classification problems on complex and massive data sets. In this paper we give the formal description of the method and present the results of its application to the evaluation of photometric redshifts for quasars. The data set used for the experiment was obtained by merging four different surveys (SDSS, GALEX, UKIDSS and WISE), thus covering a wide range of wavelengths from the UV to the mid-infrared. The method is able i) to achieve a very high accuracy; ii) to drastically reduce the number of outliers and catastrophic objects; iii) to discriminate among parameters (or features) on the basis of their significance, so that the number of features used for training and analysis can be optimized in order to reduce both the computational demands and the effects of degeneracy. The best experiment, which makes use of a selected combination of parameters drawn from the four surveys, leads, in terms of DeltaZnorm (i.e. (zspec-zphot)/(1+zspec)), to an average of DeltaZnorm = 0.004, a standard deviation sigma = 0.069 and a Median Absolute Deviation MAD = 0.02 over the whole redshift range (i.e. zspec <= 3.6), defined by the 4-survey cross-matched spectroscopic sample. The fraction of catastrophic outliers, i.e. of objects with photo-z deviating more than 2sigma from the spectroscopic value is < 3%, leading to a sigma = 0.035 after their removal, over the same redshift range. The method is made available to the community through the DAMEWARE web application.Comment: 38 pages, Submitted to ApJ in February 2013; Accepted by ApJ in May 201

Person-organization fit in the employee selection process: an instructive framework for practitioners and implications for human resource development (HRD)

Includes bibliographical references.Leaders in modern organizations seem recently concerned with workforce turnover and strategies for hiring and selecting employees who have a low risk of early departure. The concept of screening employees for "fit" with the organization as a key strategy for reducing turnover is well documented. However, communication of the research findings to practitioners is limited. Additionally, the role of Human Resource Development (HRD) in developing people and preparing the organization to implement P-O fit strategies remains relatively understudied. To contribute to the P-O fit literature and HRD, this article performs an integrative literature review on P-O fit with a specific focus on organizational selection processes. An integrated process model for using P-O fit in the organizational selection process is presented

Old Media vs. New Media: Characterizations of Free Speech during Times of War

Old Media vs. New Media: Characterizations of Free Speech During Times of War Jamie Mercurio Faculty Sponsor: Dr. Ian Reyes, Communication Studies If citizens want their voices to be heard, they must know how to make them be heard. This project will outline and discuss several situations throughout recent history in which citizens with significant statements to make managed to catch the eye of the mass media and practically become household names. Each of the cases plays upon American First Amendment rights against a backdrop of two noteworthy time periods in American history: the Vietnam War era (specifically the late 1960s) and the more current, post 9/11 age of American involvement in Iraq and Afghanistan. The purpose of this work is to better understand effective grassroots political communication in a changing media environment. Beginning with a summary of the First Amendment to the Constitution in its original historical context, the project details the changes in mass communication and media technology from the spread of television culture in the 1960s to modern America’s internet culture, discussing censorship in each respective context. The project begins with two First Amendment cases from the Vietnam War period, Tinker vs. Des Moines and United States vs. O’Brien, arguing that these cases demonstrate effective public protest during the older media age of the Vietnam War era. Then, the post 9/11 period is analyzed through Snyder vs. Phelps (of the Westboro Baptist Church), and the scandal surrounding Julian Assange and Wikileaks, representing effective protest speech in the new media age

Meaning at work

Includes bibliographical references.The search for meaning is a human activity that has transcended centuries of human civilization. As applied disciplines that investigate the development of organizations and the humans who comprise them, organization development (OD) and human resource development (HRD) scholars and practitioners have engaged in a steady stream of research and theorizing related to what "meaning" or "meaningfulness" in work is, how it develops, and most prominently in the literature, how it is operationalized. This paper seeks to add to the understanding of the concept of the meaningfulness of work through engaging in a critical analysis of the historical and theoretical assumptions of the meaningfulness of work and how these assumptions developed over time. In addition, through the interpretation of the reviewed theory, this paper will discuss the implications for future research on the meaning of work

Weak Lensing Mass Reconstruction of the Galaxy Cluster Abell 209

Weak lensing applied to deep optical images of clusters of galaxies provides a powerful tool to reconstruct the distribution of the gravitating mass associated to these structures. We use the shear signal extracted by an analysis of deep exposures of a region centered around the galaxy cluster Abell 209, at redshift z=0.2, to derive both a map of the projected mass distribution and an estimate of the total mass within a characteristic radius. We use a series of deep archival R-band images from CFHT-12k, covering an area of 0.3 deg^2. We determine the shear of background galaxy images using a new implementation of the modified Kaiser-Squires-Broadhurst pipeline for shear determination, which we has been tested against the ``Shear TEsting Program 1 and 2'' simulations. We use mass aperture statistics to produce maps of the 2 dimensional density distribution, and parametric fits using both Navarro-Frenk-White (NFW) and singular-isothermal-sphere profiles to constrain the total mass. The projected mass distribution shows a pronounced asymmetry, with an elongated structure extending from the SE to the NW. This is in general agreement with the optical distribution previously found by other authors. A similar elongation was previously detected in the X-ray emission map, and in the distribution of galaxy colours. The circular NFW mass profile fit gives a total mass of M_{200} = 7.7^{+4.3}_{-2.7} 10^{14} solar masses inside the virial radius r_{200} = 1.8\pm 0.3 Mpc. The weak lensing profile reinforces the evidence for an elongated structure of Abell 209, as previously suggested by studies of the galaxy distribution and velocities.Comment: accepted by A&A, 15 pages, 11 figure