Transitional Dynamics and Economic Growth in the Neoclassical Model

An understanding of the qualitative nature of the transitional dynamics of the neociassical model - the process of convergence from an initial capital stock to a steady state growth path - is a key part of the shared knowledge of most economists. It forms the basis, for example, of the widespread interest in hypotheses about convergence of levels of national economic activity. Based on several quantitative experiments undertaken in the 1960s with fixed savings rates versions of the neoclassical model, many economists further believe that the transition process can be lengthy, potentially rationalizing differences in growth rates across countries that are sustained for decades. In this paper, we undertake a systematic quantitative investigation of transitional dynamics within the most widely employed versions of the neoclassical model with interteorally optimizing households. Lengthy transitional episodes arise only if there is very low intertemporal substitution. But, more important, we find that the simplest neoclassical model inevitably generates a central implication that is traced to the production technology. Whenever we try to use it to explain major growth episodes, the model produces a rate of return that is counterfactually high in the early stages of development. For example, in seeking to account for U.S-Japan differences in post war growth as a consequence of differences in end-of-war capital, we find that the immediate postwar rate of return in Japan would have had to exceed 500% per annum. Frequently employed variants of the basic neoclassical model - those that introduce adjustment costs, separate production and consumption sectors, and international capital mobility - can potentially sweep this marginal product implication under the rug. However, such alterations necessarily cause major discrepancies to arise in other areas. With investment adjustment costs, for example, the implications resurface in counterfactual variations in Tobin's Q. We interpret our results as illustrating two important principles. First, systematic quantitative investigation of familiar models can provide surprising new insights into their practical operation. Second, explanation of sustained cross country differences in growth rates will require departure from the familiar neoclassical environment.

Equivariant intersection cohomology of the circle actions

In this paper, we prove that the orbit space B and the Euler class of an action of the circle S^1 on X determine both the equivariant intersection cohomology of the pseudomanifold X and its localization. We also construct a spectral sequence converging to the equivariant intersection cohomology of X whose third term is described in terms of the intersection cohomology of B.Comment: Final version as accepted in RACSAM. The final publication is available at springerlink.com; Revista de la Real Academia de Ciencias Exactas, Fisicas y Naturales. Serie A. Matematicas, 201

LRG-BEASTS III: Ground-based transmission spectrum of the gas giant orbiting the cool dwarf WASP-80

We have performed ground-based transmission spectroscopy of the hot Jupiter orbiting the cool dwarf WASP-80 using the ACAM instrument on the William Herschel Telescope (WHT) as part of the LRG-BEASTS programme. This is the third paper of a ground-based transmission spectroscopy survey of hot Jupiters using low-resolution grism spectrographs. We observed two transits of the planet and have constructed transmission spectra spanning a wavelength range of 4640-8840A. Our transmission spectrum is inconsistent with a previously claimed detection of potassium in WASP-80b's atmosphere, and is instead most consistent with a haze. We also do not see evidence for sodium absorption at a resolution of 100A.Comment: 11 pages, 9 figures. Accepted for publication in MNRA

Molecular Beam Research

Contains reports on two research projects

Performance of a Harbor Embankment

An instrumentation program to monitor deformations and pore pressures in foundation soils during construction of a container wharf and backlands fill at the Port of Los Angeles is described in this paper. Inclinometers, vertical settlement systems, and pneumatic pore-pressure transducers were used to monitor the performance of a silty clay during various phases of container wharf and backlands construction. Results of the monitoring program and their impacts on wharf construction are presented and discussed. Instrumentation program refinements that were required during data gathering and interpretation are also noted

Current Landscape of Screening for Abdominal Aortic Aneurysms in Females

There is some controversy over if females are under-screened for abdominal aortic aneurysms (AAAs). The USPSTF 2019 AAA screening guidelines give an I recommendation for females 65-75 who smoke, yet the Society for Vascular Surgery (SVS) highly recommends with strong evidence a 1-time screening ultrasound for men or women age 65-75 with a tobacco history. This project entails a 10-minute recorded PowerPoint educational session for Milton Family Practice providers on the current landscape of AAA screening in females including differing practice guidelines and their histories, cause of said discrepancies, associated cost and insurance coverage, and suggested creative solutions to billing difficulties as well as provider response and feedback

LFV and Dipole Moments in Models with A4 Flavour Symmetry

It is presented an analysis on lepton flavour violating transitions, leptonic magnetic dipole moments and electric dipole moments in a class of models characterized by the flavour symmetry A4 x Z3 x U(1)_FN, whose choice is motivated by the approximate Tri-Bimaximal mixing observed in neutrino oscillations. A low-energy effective Lagrangian is constructed, where these effects are dominated by dimension six operators, suppressed by the scale M of new physics. All the flavour breaking effects are universally described by the vacuum expectation values of a set of spurions. Two separate cases, a supersymmetric and a general one, are described. An upper limit on the reactor angle of a few percent is concluded.Comment: 10 pages, 1 figure. Adapted from a talk given at "DISCRETE'08: Symposium on Prospects in the Physics of Discrete Symmetries", December 11-16 2008, Valencia, Spai

The ferroelectric transition in YMnO3_3 from first principles

We have studied the structural phase transition of multiferroic YMnO$_3$ from first principles. Using group-theoretical analysis and first-principles density functional calculations of the total energy and phonons, we perform a systematic study of the energy surface around the prototypic phase. We find a single instability at the zone-boundary which couples strongly to the polarization. This coupling is the mechanism that allows multiferroicity in this class of materials. Our results imply that YMnO$_3$ is an improper ferroelectric. We suggest further experiments to clarify this point.Comment: published version, PRB (rapid comm), slight change in presentatio

Toward precise constraints on growth of massive black holes

Growth of massive black holes (MBHs) in galactic centers comes mainly from gas accretion during their QSO/AGN phases. In this paper we apply an extended Soltan argument, connecting the local MBH mass function with the time-integral of the QSO luminosity function, to the demography of MBHs and QSOs from recent optical and X-ray surveys, and obtain robust constraints on the luminosity evolution (or mass growth history) of individual QSOs (or MBHs). We find that the luminosity evolution probably involves two phases: an initial exponentially increasing phase set by the Eddington limit and a following phase in which the luminosity declines with time as a power law (with a slope of -1.2--1.3) set by a self-similar long-term evolution of disk accretion. Neither an evolution involving only the increasing phase with a single Eddington ratio nor an exponentially declining pattern in the second phase is likely. The period of a QSO radiating at a luminosity higher than 10% of its peak value is about (2-3)x10^8 yr, during which the MBH obtains ~80% of its mass. The mass-to-energy conversion efficiency is $0.16\pm0.04 ^{+0.05}_{-0}$, with the latter error accounting for the maximum uncertainty due to Compton-thick AGNs. The expected Eddington ratios in QSOs from the constrained luminosity evolution cluster around a single value close to 0.5-1 for high-luminosity QSOs and extend to a wide range of lower values for low-luminosity ones. The Eddington ratios for high luminosity QSOs appear to conflict with those estimated from observations (~0.25) by using some virial mass estimators for MBHs in QSOs unless the estimators systematically over-estimate MBH masses by a factor of 2-4. We also infer the fraction of optically obscured QSOs ~60-80%. Further applications of the luminosity evolution of individual QSOs are also discussed.Comment: 25 pages, 13 figures, ApJ in pres