Time evolution of intrinsic alignments of galaxies

Intrinsic alignments (IA), correlations between the intrinsic shapes and orientations of galaxies on the sky, are both a significant systematic in weak lensing and a probe of the effect of large-scale structure on galactic structure and angular momentum. In the era of precision cosmology, it is thus especially important to model IA with high accuracy. Efforts to use cosmological perturbation theory to model the dependence of IA on the large-scale structure have thus far been relatively successful; however, extant models do not consistently account for time evolution. In particular, advection of galaxies due to peculiar velocities alters the impact of IA, because galaxy positions when observed are generally different from their positions at the epoch when IA is believed to be set. In this work, we evolve the galaxy IA from the time of galaxy formation to the time at which they are observed, including the effects of this advection, and show how this process naturally leads to a dependence of IA on the velocity shear. We calculate the galaxy-galaxy-IA bispectrum to tree level (in the linear matter density) in terms of the evolved IA coefficients. We then discuss the implications for weak lensing systematics as well as for studies of galaxy formation and evolution. We find that considering advection introduces nonlocality into the bispectrum, and that the degree of nonlocality represents the memory of a galaxy's path from the time of its formation to the time of observation. We discuss how this result can be used to constrain the redshift at which IA is determined and provide Fisher estimation for the relevant measurements using the example of SDSS-BOSS.Comment: 30 pages, 5 figures, 2 table

Income Redistribution, Consumer Credit, and Keeping Up with the Riches

In this study, we set up a dynamic stochastic general equilibrium (DSGE) model with upward looking consumption comparison and show that consumption externalities are an important driver of consumer credit dynamics. Our model economy is populated by two different household types. Investors, who hold the economy\u27s capital stock, own the firms and supply credit, and workers, who supply labor and demand credit to finance consumption. Furthermore, workers condition their consumption choice on the investors\u27 level of consumption. We estimate the model and find a significant keeping up mechanism by matching business cycle statistics. In reproducing credit moments, our proposed model significantly outperforms a model version in which we abstract from consumption externalities

The Economic Ramifications Of Multinational Corporations: Foreign Direct Investments (FDIs) And The Connection Between Technological Transfer And ProductivityGrowth Within Host Economies

This study conducts an investigation into the impact of technology transfer as a derivative of FDI on productive efficiency within developing Asian economies through the implementation of applied empirical analysis

Taking the Pulse of Undergraduate Introductory Geographic Information Systems Courses

As colleges and universities expand their geographic information systems (GIS) course offerings, the pedagogies involved in teaching such courses ought to be critically evaluated. Existing research concerning the teaching of geospatial technologies has been characterized as “sparse, inconsistent, and overly anecdotal” (Baker et al., 2015, p. 118). Answering the call for “more systematic and replicable” (p. 118) GIS education research, this study adopted a suite of mixed methods used within other discipline-based education research (DBER) and deployed them in introductory GIS courses. These methods included classroom observation protocols, interview protocols, focus group protocols, and student questionnaires. This research had three aims: evaluate the utility of existing classroom observation protocols to characterize the teaching practices of introductory GIS courses, contextualize the relationship between instructors’ teaching beliefs and teaching practice, and describe the interests, motivations, learning strategies, and course experiences of introductory GIS students. Over the course of two semesters, 33 GIS class and lab sessions were observed using the Classroom Observation Protocol for Undergraduate STEM (COPUS; Smith, Jones, Gilbert, & Wieman, 2013) and the Reformed Teaching Observation Protocol (RTOP; Sawada et al., 2002). Both were found to provide an adequate mechanism to characterize the teaching within GIS classrooms. Most of the observed class sessions were found to be teacher rather than student-centered and teaching practices were found to vary between lecture- and lab-oriented class sessions. Multiple facets of instructors’ teaching beliefs were identified and classified by interviewing the six participating instructors with the Teacher Beliefs Interview protocol (Luft & Roehrig, 2007). Instructors’ teaching beliefs were compared to observed teaching practices. Overall, the instructors’ teaching practices were found to be quite consistent with their teaching beliefs. Students’ responses to a series of quantitative surveys were integrated with qualitative data gathered in interviews and focus groups. This mixed-methods integration provided detailed insight in the students’ interests, motivations, learning strategies, and course experiences. These students were found to be motivated by disciplinary relevance and task value, engaged in a variety of learning strategies, and, despite high satisfaction with the courses overall, rated the appropriateness of assessment and workload low. These findings taken together suggest that the tools of discipline-based education research demonstrate the potential of systematic and replicable process to study GIS pedagogy. Further adoption of these tools could provide a comprehensive pulse of GIS education laying the groundwork for establishing research-backed best practices

Halo occupation distribution modelling of green valley galaxies

We present a clustering analysis of near-ultraviolet (NUV)–optical colour selected luminosity bin samples of green valley galaxies. These galaxy samples are constructed by matching the Sloan Digital Sky Survey Data Release 7 with the latest Galaxy Evolution Explorer source catalogue which provides NUV photometry. We present cross-correlation function measurements and determine the halo occupation distribution of green valley galaxies using a new multiple tracer analysis technique. We extend the halo occupation formalism, which describes the relation between galaxies and halo mass in terms of the probability P(N, Mh) that a halo of given mass Mh contains N galaxies, to model the cross-correlation function between a galaxy sample of interest and multiple tracer populations simultaneously. This method can be applied to commonly used luminosity threshold samples as well as to colour and luminosity bin selected galaxy samples, and improves the accuracy of clustering analyses for sparse galaxy populations. We confirm the previously observed trend that red galaxies reside in more massive haloes and are more likely to be satellite galaxies than average galaxies of similar luminosity. While the change in central galaxy host mass as a function of colour is only weakly constrained, the satellite fraction and characteristic halo masses of green satellite galaxies are found to be intermediate between those of blue and red satellite galaxies

Geographic inequities in local higher education opportunities? : identifying college deserts with critical GIS

Dr. Timothy Matisziw, Thesis Supervisor.Field of study: Geography."May 2017."In a world where one's future is heavily impacted by having postsecondary education, access to college is a pertinent research topic. Access is a widely researched topic, but only recently has college access been studied specifically. This study proposes a geographic information systems based methodology for quantifying college access at multiple spatial scales. This methodology was implemented with the Python programming language and ArcGIS. A sample of six metropolitan statistical areas were identified and analyzed using the developed methodology. Within this sample, college access varied primarily by socio-economic status although some variation between race/ethnicity was identified. Further research is needed to assess whether these trends are generalizable. Quantification of college access will aid policy-makers to prepare reforms to reduce the inequity of college access.Includes bibliographical references (pages 98-101)

The Integral Equation Method for a Steady Kinematic Dynamo Problem

With only a few exceptions, the numerical simulation of cosmic and laboratory hydromagnetic dynamos has been carried out in the framework of the differential equation method. However, the integral equation method is known to provide robust and accurate tools for the numerical solution of many problems in other fields of physics. The paper is intended to facilitate the use of integral equation solvers in dynamo theory. In concrete, the integral equation method is employed to solve the eigenvalue problem for a hydromagnetic dynamo model with a spherically symmetric, isotropic helical turbulence parameter alpha. Three examples of the function alpha(r) with steady and oscillatory solutions are considered. A convergence rate proportional to the inverse squared of the number of grid points is achieved. Based on this method, a convergence accelerating strategy is developed and the convergence rate is improved remarkably. Typically, quite accurate results can be obtained with a few tens of grid points. In order to demonstrate its suitability for the treatment of dynamos in other than spherical domains, the method is also applied to alpha^2 dynamos in rectangular boxes. The magnetic fields and the electric potentials for the first eigenvalues are visualized.Comment: 22 pages, 18 figures, to appear in J. Comp. Phy

Dealing with Missing Data: A Comparative Exploration of Approaches Using the Integrated City Sustainability Database

Studies of governments and local organizations using survey data have played a critical role in the development of urban studies and related disciplines. However, missing data pose a daunting challenge for this research. This article seeks to raise awareness about the treatment of missing data in urban studies research by comparing and evaluating three commonly used approaches to deal with missing data—listwise deletion, single imputation, and multiple imputation. Comparative analyses illustrate the relative performance of these approaches using the second-generation Integrated City Sustainability Database (ICSD). The results demonstrate the benefit of using an approach to missing data based on multiple imputation, using a theoretically informed and statistically supported set of predictor variables to develop a more complete sample that is free of issues raised by nonresponse in survey data. The results confirm the usefulness of the ICSD in the study of environmental and sustainability and other policy in U.S. cities. We conclude with a discussion of results and provide a set of recommendations for urban researcher scholars