Separation of Coupled Systems of Schrodinger Equations by Darboux transformations

Darboux transformations in one independent variable have found numerous applications in various field of mathematics and physics. In this paper we show that the extension of these transformations to two dimensions can be used to decouple systems of Schrodinger equations and provide explicit representation for three classes of such systems. We show also that there is an elegant relationship between these transformations and analytic complex matrix functions.Comment: 14 page

Development of S-13G-type coatings as engineering materials Final report, 1 Sep. 1966 - 31 Aug. 1968

S-13G type thermal control coatings for space application

A Feynman-Kac Formula for Anticommuting Brownian Motion

Motivated by application to quantum physics, anticommuting analogues of Wiener measure and Brownian motion are constructed. The corresponding Ito integrals are defined and the existence and uniqueness of solutions to a class of stochastic differential equations is established. This machinery is used to provide a Feynman-Kac formula for a class of Hamiltonians. Several specific examples are considered.Comment: 21 page

The behavior of several white pigments as determined by in situ reflectance measurements of irradiated specimens

Reflectance measurements of irradiated specimens of zinc oxide and zinc orthotitanate white pigment material

Does environment affect the star formation histories of early-type galaxies?

Differences in the stellar populations of galaxies can be used to quantify the effect of environment on the star formation history. We target a sample of early-type galaxies from the Sloan Digital Sky Survey in two different environmental regimes: close pairs and a general sample where environment is measured by the mass of their host dark matter halo. We apply a blind source separation technique based on principal component analysis, from which we define two parameters that correlate, respectively, with the average stellar age (eta) and with the presence of recent star formation (zeta) from the spectral energy distribution of the galaxy. We find that environment leaves a second order imprint on the spectra, whereas local properties - such as internal velocity dispersion - obey a much stronger correlation with the stellar age distribution.Comment: 5 pages, 2 figures. Proceedings of JENAM 2010, Symposium 2: "Environment and the formation of galaxies: 30 years later

Development of space stable thermal control coatings Triannual report, Mar. 1 - Jul. 31, 1967

Ultraviolet irradiation effects on space stable thermal control zinc coating

MODEL: A General Program for Estimating Parametrized Model Schedules of Fertility, Mortality, Migration, and Marital and Labor Force Status Transitions

Demography has been characterized as the quantitative study of fundamental demographic processes, such as mortality, fertility, migration, and marriage. These processes may be viewed as transitions that individuals experience during the course of their lifecycle. Individuals are born, age with the passage of time, enroll in school, enter the labor force, get married, reproduce, migrate from one region to another, retire, and ultimately die. These transitions contribute to changes in various population stocks through simple accounting identities. For example, the number of married people at the end of each year is equal to the number at the beginning of the year plus new marriages and arrivals of married migrants less divorces, deaths, widowings, and the outmigration of part of the married population. The study of transition patterns generally begins with the collection of data and the estimation of missing observations, continues with the calculation of the appropriate rates and corresponding probabilities, and often ends with the generation of simple projections of the future conditions that would arise were these probabilities to remain unchanged

The Spatial Reproductive Value and the Spatial Momentum of Zero Population Growth

This paper develops the concept of spatial reproductive value and illustrates how such a notion may be used to trace out quantitatively the geographical impacts of a sudden reduction in fertility to bare replacement level. Such a reduction does not immediately produce zero population growth in populations that previously experienced high birth rates. The built-in momentum for continued growth and its spatial dimension may be assessed with the aid of spatial reproductive values

More Computer Programs for Spatial Demographic Analysis

This report presents the algorithms and lists the FORTRAN IV codes of computer programs for the analysis of multiregional population systems. It is a continuation of the IIASA report RM-76-58. The following topics are included: mobility and fertility analyses of life table and stable populations; methodology and applications of the spatial reproductive value; and the study of the spatial demographic impacts of fertility reduced to replacement level. This report focuses on the interpretation of the output of the computer programs

Parametrized Multistate Population Projections

This paper reports progress on the development of a population projection process that emphasizes model selection over demographic accounting. Transparent multiregional/multistate population projections that rely on parametrized model schedules are illustrated, together with simple techniques that extrapolate the recent trends exhibited by the parameters of such schedules. The parametrized schedules condense the amount of demographic information, expressing it in a language and variables that are more readily understood by the users of the projections. In addition, they permit a concise specification of the expected temporal patterns of variation among these variables, and they allow a disaggregated focus on demographic change that otherwise would not be feasible