The Role of Dust in Models of Population Synthesis

We have employed state-of-the-art evolutionary models of low and intermediate-mass AGB stars, and included the effect of circumstellar dust shells on the spectral energy distribution (SED) of AGB stars, to revise the Padua library of isochrones (Bertelli et al. 1994). The major revision involves the thermally pulsing AGB phase, that is now taken from fully evolutionary calculations by Weiss & Ferguson (2009). Two libraries of about 600 AGB dust-enshrouded SEDs each have also been calculated, one for oxygen-rich M-stars and one for carbon-rich C-stars. Each library accounts for different values of input parameters like the optical depth {\tau}, dust composition, and temperature of the inner boundary of the dust shell. These libraries of dusty AGB spectra have been implemented into a large composite library of theoretical stellar spectra, to cover all regions of the Hertzsprung-Russell Diagram (HRD) crossed by the isochrones. With the aid of the above isochrones and libraries of stellar SEDs, we have calculated the spectro-photometric properties (SEDs, magnitudes, and colours) of single-generation stellar populations (SSPs) for six metallicities, more than fifty ages (from 3 Myr to 15 Gyr), and nine choices of the Initial Mass Function. The new isochrones and SSPs have been compared to the colour-magnitude diagrams (CMDs) of field populations in the LMC and SMC, with particular emphasis on AGB stars, and the integrated colours of star clusters in the same galaxies, using data from the SAGE (Surveying the Agents of Galaxy Evolution) catalogues. We have also examined the integrated colours of a small sample of star clusters located in the outskirts of M31. The agreement between theory and observations is generally good. In particular, the new SSPs reproduce the red tails of the AGB star distribution in the CMDs of field stars in the Magellanic Clouds.Comment: Accepted for publication in MNRA

Cosmological interpretation of the color-magnitude diagrams of galaxy clusters

We investigate the color-magnitude diagram (CMD) of cluster galaxies in the hierarchical $\Lambda$-CDM cosmological scenario using both single stellar populations and simple galaxy models. First, we analyze the effect of bursts and mergers and companion chemical pollution and rejuvenation of the stellar content on the integrated light emitted by galaxies. The dispersion of the galaxy magnitudes and colors on the $M_V-(B-V)$ plane is mainly due to mixing of ages and metallicities of the stellar populations, with mergers weighting more than bursts of similar mass fractions. The analysis is made using the Monte-Carlo technique applied to ideal model galaxies reduced to single stellar populations with galaxy-size mass to evaluate mass, age and metallicity of each object. We show that separately determining the contributions by bursts and mergers leads to a better understanding of observed properties of CMD of cluster galaxies. Then we repeat the analysis using suitable chemo-photometric models of galaxies whose mass is derived from the cosmological predictions of the galaxy content of typical clusters. Using the halo mass function and the Monte-Carlo technique, we derive the formation redshift of each galaxy and its photometric history. These are used to simulate the CMD of the cluster galaxies. The main conclusion is that most massive galaxies have acquired the red color they show today in very early epochs and remained the same ever since. The simulations nicely reproduce the Red Sequence, the Green Valley and the Blue Cloud, the three main regions of the CMD in which galaxies crowd.Comment: Accepted for publication in Ap

How Do the BRICs Stack Up? Adding Brazil, Russia,India, and China to the Environment Component of the Commitment to Development Index

The Commitment to Development Index (CDI) ranks 21 of the world’s richest countries on their dedication to policies that benefit the five billion people living in poorer nations. Moving beyond simple comparisons of foreign aid, the CDI ranks countries on seven themes: quantity and quality of foreign aid, openness to developing-country exports, policies that influence investment, migration policies, stewardship of the global environment, security policies and support for creation and dissemination of new technologies. This year for the first time, CGD research fellow David Roodman extended the environment component of the Index to cover four of the biggest developing countries: Brazil, Russia, India and China, a group Goldman Sachs dubbed the “BRICs.” This working paper explores the indicators that make up the environment component (global climate, sustainable fisheries, and biodiversity and global ecosystems) and explains how the BRIC countries stack up to their right-country counterparts. He finds that the BRICs score remarkably well compared to the 21 rich countries covered by the Index: when thrown in with the usual 21, they rank second, fourth, fifth, and eleventh. They generally perform well on the greenhouse gas emissions, consumption of ozone-depleting substances, and tropical timber imports. And the BRICs have joined important international environmental accords. As a group, their major weakness is low gas taxes. In addition, Amazon deforestation and heavy fossil fuel use pull Brazil and Russia, respectively, below the CDI 21 average on greenhouse emissions per capita. China’s abstention from the U.N. fisheries agreement puts it a half point below the other BRICs.environment, Commitment to Development Index (CDI)

UMPus, Vol. 3, No. 21, 3/10/1965

Dr. Cassara at UMP -- The Future of UMP -- Maine Day -- Student Senate Presidency Elections -- Inside Sports -- Parking Restrictions -- Library University of Maine Portland Campus Recently Added Bookshttps://digitalcommons.usm.maine.edu/umpus/1009/thumbnail.jp

The Senator Nat G. Kiefer University of New Orleans Lakefront Arena: An Internship Academic Report

This report discusses my internship with the Lakefront Arena at the University of New Orleans. Included in this report is a breakdown of the Arena’s management and facilities, internship overview, organization analysis based upon my observations, best practices comparing similar venues, and recommendations to the Lakefront Arena. The internship concluded with a job offer as the interim Campus Booking Coordinator, to which I accepted

Modelling galaxy spectra in presence of interstellar dust-III. From nearby galaxies to the distant Universe

Improving upon the standard evolutionary population synthesis (EPS) technique, we present spectrophotometric models of galaxies whose morphology goes from spherical structures to discs, properly accounting for the effect of dust in the interstellar medium (ISM). These models enclose three main physical components: the diffuse ISM composed by gas and dust, the complexes of molecular clouds (MCs) where active star formation occurs and the stars of any age and chemical composition. These models are based on robust evolutionary chemical models that provide the total amount of gas and stars present at any age and that are adjusted in order to match the gross properties of galaxies of different morphological type. We have employed the results for the properties of the ISM presented in Piovan, Tantalo & Chiosi (2006a) and the single stellar populations calculated by Cassar\`a et al. (2013) to derive the spectral energy distributions (SEDs) of galaxies going from pure bulge to discs passing through a number of composite systems with different combinations of the two components. The first part of the paper is devoted to recall the technical details of the method and the basic relations driving the interaction between the physical components of the galaxy. Then, the main parameters are examined and their effects on the spectral energy distribution of three prototype galaxies are highlighted. We conclude analyzing the capability of our galaxy models in reproducing the SEDs of real galaxies in the Local Universe and as a function of redshift.Comment: 22 pages, 10 figures, submitted to MNRA

Cosmic Star Formation: a simple model of the SFRD(z)

We investigate the evolution of the cosmic star formation rate density (SFRD) from redshift z=20 to z=0 and compare it with the observational one by Madau and Dickinson derived from recent compilations of UV and IR data. The theoretical SFRD(z) and its evolution are obtained using a simple model which folds together the star formation histories of prototype galaxies designed to represent real objects of different morphological type along the Hubble sequence and the hierarchical growing of structures under the action of gravity from small perturbations to large scale objects in \Lambda-CDM cosmogony, i.e. the number density of dark matter halos N(M,z). Although the overall model is very simple and easy to set up, it provides results that well mimic those obtained from large scale N-body simulations of great complexity. The simplicity of our approach allows us to test different assumptions for the star formation law in galaxies, the effects of energy feedback from stars to interstellar gas and the efficiency of galactic winds, and also the effect of N(M,z). The result of our analysis is that in the framework of the hierarchical assembly of galaxies the so-called time-delayed star formation under plain assumptions mainly for the energy feedback and galactic winds can reproduce the observational SFRD(z).Comment: ApJ (accepted for publication

Hosea Ballou, preacher of universal salvation

Thesis (Ph.D)--Boston UniversityThis dissertation is devoted to a study of the life and thought of Hosea Ballou (1771-1852), the most prominent of the leaders of American Universalism. No major work has been published in this field since 1889; there has never been a careful examination of his thought and an attempt to trace its sources. Ballou was the son of a Calvinistic Baptist minister. At eighteen he was converted to Universalism and began preaching the new "heresy" in about 1791 on a Calvinistic basis. Between 1791 and 1795 Ballou's thought went through a radical transformation. This study attempts to show that the resultant unitarianism of Ballou was the fruit of his reading of Ethan Allen's deistical work, Reason Only Oracle of Man. Allen, with his great stress on reason, destroyed Ballou's faith in the doctrines of the trinity and the divinity of Christ, the infinity of sin, and the traditional theories of the atonement. With the help of Charles Chauncy's Salvation of All Men, which justified not only his belief in Universal salvation but also helped him to substitute the Arian for the trinitarian view of Christ, and to view the atonement as the reconciliation of man to God and not vice versa; and Ferdinand Olivier Petitpierrets Thoughts on the Divine Goodness, which helped him to see Christ's atonement as an expression of God's love, and also gave him a firm base for a theory of determinism; Ballou began the reconstruction of his religious thought. His first sermon on a unitarian and Arian base was preached in 1795. Within ten years, through the power of his argumentation, and against the opposition of the prominent Universalist John Murray, Ballou had converted the Universalist ministry to Unitarianism. In 1805 his new thought was fully systematized in! Treatise on Atonement, a brilliant piece of reasoning and debating expressed in the language of rural America [TRUNCATED