5,278 research outputs found

    Immigrants and Homeownership in Urban America: An Examination of Nativity, Socio-economic Status and Place

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    A unique pilot project conducted in America's small and medium-sized cities shows that broad-based community coalitions can proactively integrate the newcomers who are increasingly transforming Main St., USA. In the first project of its kind, a consortium of leading organizations in three mid-sized metropolitan areas undertook inclusive community-building. The project's final report contains valuable findings for policymakers, funders and organizations collectively approaching the challenge of helping newcomers adapt to their new communities and local communities welcome newcomers

    Topological Properties from Einstein's Equations?

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    In this work we propose a new procedure for to extract global information of a space-time. We considered a space-time immersed in a higher dimensional space and we formulate the equations of Einstein through of the Frobenius conditions to immersion. Through of an algorithm and the implementation into algebraic computing system we calculate normal vectors from the immersion to find out the second fundamental form. We make a application for space-time with spherical symmetry and static. We solve the equations of Einstein to the vacuum and we obtain space-times with different topologies.Comment: 7 pages, accepted for publication in Int. J. Mod. Phys.

    Embedding Versus Immersion in General Relativity

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    We briefly discuss the concepts of immersion and embedding of space-times in higher-dimensional spaces. We revisit the classical work by Kasner in which he constructs a model of immersion of the Schwarzschild exterior solution into a six-dimensional pseudo-Euclidean manifold. We show that, from a physical point of view, this model is not entirely satisfactory since the causal structure of the immersed space-time is not preserved by the immersion.Comment: 5 page

    Incomplete Transition Complexity of Basic Operations on Finite Languages

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    The state complexity of basic operations on finite languages (considering complete DFAs) has been in studied the literature. In this paper we study the incomplete (deterministic) state and transition complexity on finite languages of boolean operations, concatenation, star, and reversal. For all operations we give tight upper bounds for both description measures. We correct the published state complexity of concatenation for complete DFAs and provide a tight upper bound for the case when the right automaton is larger than the left one. For all binary operations the tightness is proved using family languages with a variable alphabet size. In general the operational complexities depend not only on the complexities of the operands but also on other refined measures.Comment: 13 page

    Measuring Faculty Teaching Effectiveness Using Conditional Fixed Effects

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    Using a dataset of 48 faculty members and 88 courses over 26 semesters, the authors estimate Student Evaluation of Teaching (SET) ratings that are conditional on a multitude of course, faculty, and student attributes. They find that ratings are lower for required courses and those where students report a lower prior level of interest. Controlling for these variables substantially alters the SET ratings for many instructors. The average absolute value of the difference between the faculty ratings controlling just for time effects and fully conditional ratings is nearly one-half of a standard deviation in the students’ rating of how much they learned. This difference produces a change in quartile rank for over half the sample across two summary course evaluation measures

    Could tariffs be pro-cyclical?

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    Conventional wisdom says that tariffs are counter-cyclical. We analyze the relationship between business cycles and applied MFN tariffs using a disaggregated product-level panel dataset covering 72 countries between 2000 and 2011. Strikingly, and counter to conventional wisdom, we find that tariffs are pro-cyclical. Further investigation reveals that this pro-cyclicality is driven by the tariff setting behavior of developing countries; tariffs are acyclical in developed countries. We present evidence that pro-cyclical market power drives the pro-cyclicality of tariffs in developing countries, providing further evidence of the importance of terms of trade motivations in explaining trade policy

    Learning Effects of the Flipped Classroom in a Principles of Microeconomics Course Running Header: Flipped Principles of Micro

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    The authors of this article estimate the learning effects of the flipped classroom format using data from 16 sections of principles of microeconomics over a 4-year period. The experimental design is unique in that two treatment and two control sections were taught during the fall semester in four consecutive years. Further, the instructor switched the time of day when the treatment and control sections were taught each year. Controlling for gender, ACT score, a normed high school GPA, Pell Grant award, time of day, and initial knowledge of economics, the authors find no evidence of increased learning using end-of-semester measures for students in the flipped classroom in comparison to sections with a moderate amount of active learning

    Costly distribution and the non-equivalence of tariffs and quotas

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    When governments impose a quota or tariff on imports, it is well known that the resulting rents and revenues trigger costly rent-seeking and revenue-seeking activities, which are welfare-reducing and may be economically more significant than the efficiency losses resulting from the protectionist-induced resource misallocation. Repeated interaction among firms can eliminate wasteful rent- and revenue-seeking expenditures through cooperation. We show that while aggregate outcomes are equivalent under tariffs and quotas if cooperation arises, the conditions under which cooperation arises differ by policy. This difference arises because a firm must incur additional cost to physically import and distribute the goods associated with additional quota licenses, whereas there is no such cost when it comes to consuming additional tariff revenue. Thus, quotas and tariffs are non-equivalent. We provide a simple sufficient condition under which cooperative elimination of rent-seeking under quotas is easier than cooperative elimination of revenue-seeking under tariffs and therefore a quota is the preferred policy whenever the policy admits cooperation
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