Capping the Mortgage Interest Deduction

In this paper we examine the economic implications of several policy options for capping the mortgage interest deduction (MID). We extend the standard user–cost model of owner–occupied housing to include a cap on the mortgage size receiving tax–favored status. Our user–cost estimates for taxpayers with mortgages above the current–law cap are 4.41 percent higher than estimates from a model without the cap. We simulate the share of mortgage dollars that would be subject to three alternative cap policy variants and summarize the distributional impacts of each proposal, computing the share of mortgage dollars impacted across U.S. Metropolitan Areas

Dusty Exoplanetary Debris Disks in the Single-Temperature Blackbody Plane

The 21st European Workshop on White Dwarfs was held in Austin, TX from July 23rd to 27th of 2018We present a bulk sample analysis of the metal polluted white dwarfs which also host infrared bright dusty debris disks, known to be direct signatures of an active exoplanetary accretion source. We explore the relative positions of these systems in a “single-temperature blackbody plane”, defined as the temperature and radius of a single temperature blackbody as fitted to the infrared excess. We find that the handful of dust systems which also host gaseous debris in emission congregate along the high temperature boundary of the dust disk region in the single-temperature blackbody plane. We discuss interpretations of this boundary and propose the single-temperature blackbody plane selection technique for use in future targeted searches of gaseous emission.Astronom

Inextendibility of spacetimes and Lorentzian length spaces

We study the low-regularity (in-)extendibility of spacetimes within the synthetic-geometric framework of Lorentzian length spaces developed in [KS:17]. To this end, we introduce appropriate notions of geodesics and timelike geodesic completeness and prove a general inextendibility result. Our results shed new light on recent analytic work in this direction and, for the first time, relate low-regularity inextendibility to (synthetic) curvature blow-up.Comment: 21 pages, 1 figure, made assumptions in 5.4 and 5.6 more explicit (strong causality and local TL geodesic connectedness of extension

Electronic structure methods: Augmented Waves, Pseudopotentials and the Projector Augmented Wave Method

The main goal of electronic structure methods is to solve the Schroedinger equation for the electrons in a molecule or solid, to evaluate the resulting total energies, forces, response functions and other quantities of interest. In this paper we describe the basic ideas behind the main electronic structure methods such as the pseudopotential and the augmented wave methods and provide selected pointers to contributions that are relevant for a beginner. We give particular emphasis to the Projector Augmented Wave (PAW) method developed by one of us, an electronic structure method for ab-initio molecular dynamics with full wavefunctions. We feel that it allows best to show the common conceptional basis of the most widespread electronic structure methods in materials science.Comment: to appear in: Handbook of Materials Modeling; Volume 1: Methods and Models, Sidney Yip (Ed.); Kluwer Academic Publisher

A Multiscale Diffuse-Interface Model for Two-Phase Flow in Porous Media

In this paper we consider a multiscale phase-field model for capillarity-driven flows in porous media. The presented model constitutes a reduction of the conventional Navier-Stokes-Cahn-Hilliard phase-field model, valid in situations where interest is restricted to dynamical and equilibrium behavior in an aggregated sense, rather than a precise description of microscale flow phenomena. The model is based on averaging of the equation of motion, thereby yielding a significant reduction in the complexity of the underlying Navier-Stokes-Cahn-Hilliard equations, while retaining its macroscopic dynamical and equilibrium properties. Numerical results are presented for the representative 2-dimensional capillary-rise problem pertaining to two closely spaced vertical plates with both identical and disparate wetting properties. Comparison with analytical solutions for these test cases corroborates the accuracy of the presented multiscale model. In addition, we present results for a capillary-rise problem with a non-trivial geometry corresponding to a porous medium

Regulation of AQP0 water permeability is enhanced by cooperativity.

Aquaporin 0 (AQP0), essential for lens clarity, is a tetrameric protein composed of four identical monomers, each of which has its own water pore. The water permeability of AQP0 expressed in Xenopus laevis oocytes can be approximately doubled by changes in calcium concentration or pH. Although each monomer pore functions as a water channel, under certain conditions the pores act cooperatively. In other words, the tetramer is the functional unit. In this paper, we show that changes in external pH and calcium can induce an increase in water permeability that exhibits either a positive cooperativity switch-like increase in water permeability or an increase in water permeability in which each monomer acts independently and additively. Because the concentrations of calcium and hydrogen ions increase toward the center of the lens, a concentration signal could trigger a regulatory change in AQP0 water permeability. It thus seems plausible that the cooperative modes of water permeability regulation by AQP0 tetramers mediated by decreased pH and elevated calcium are the physiologically important ones in the living lens

Our Boys

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