1,350 research outputs found
Effects of California migration
California ; Emigration and immigration ; West (U.S.) ; Federal Reserve District, 12th
Housing price cycles and prepayment rates of U.S. mortgage pools.
Empirical mortgage prepayment models generally have trouble explaining differences in mortgage prepayment speeds among pools with similar interest rates on the underlying mortgages. In this paper, we model some of the sources of termination heterogeneity across mortgage pools, particularly the role of regional variations in housing prices in generating atypical prepayment speeds. Using a sample of Freddie Mac mortgage pools from 1991-1998, we find evidence that differences in house price dynamics across regions are an important source of between-pool heterogeneity. This finding is then shown to be robust to alternative ways of parameterizing pool heterogeneity in mortgage termination models.Real property ; Mortgages
A Time Domain Approach to Power Integrity for Printed Circuit Boards
Power integrity is becoming increasingly relevant due to increases in device
functionality and switching speeds along with reduced operating voltage. Large
current spikes at the device terminals result in electromagnetic disturbances
which can establish resonant patterns affecting the operation of the whole
system. These effects have been examined using a finite difference time domain
approach to solve Maxwell's equations for the PCB power and ground plane
configuration. The simulation domain is terminated with a uniaxial perfectly
matched layer to prevent unwanted reflections. This approach calculates the
field values as a function of position and time and allows the evolution of the
field to be visualized. The propagation of a pulse over the ground plane was
observed demonstrating the establishment of a complex interference pattern
between source and reflected wave fronts and then between multiply reflected
wave fronts. This interference which affects the whole ground plane area could
adversely affect the operation of any device on the board. These resonant waves
persist for a significant time after the initial pulse. Examining the FFT of
the ground plane electric field response showed numerous resonant peaks at
frequencies consistent with the expected values assuming the PCB can be
modelled as a resonant cavity with two electric and four magnetic field
boundaries.Comment: Presented at The University of Bolton Research and Innovation
Conference, Bolton, UK. 16th September, 201
Thermally activated conductance of a silicon inversion layer by electrons excited above the mobility edge
The thermally activated conductivity sigma of an n-type inversion layer on a (100) oriented silicon surface and its derivative d sigma /dT were measured in the temperature range 1.4K-4.2K. Above T approximately=2.5K both the temperature dependence of (T/ sigma ) (d sigma /dT) and the relation between this quantity and sigma cannot be reconciled with a universal pre-exponential factor, i.e. the minimum metallic conductivity, but are shown to be satisfactorily described by a prefactor which is proportional to the temperature. The experimental results presented are consistent with activation of the number of mobile electrons above a mobility edge in the lowest sub-band, and indicate a mobility which is independent of both temperature and electron density
Association of circulating levels of MMP-8 with mortality from respiratory disease in patients with rheumatoid arthritis.
Matrix metalloproteinases (MMPs) are implicated in the destruction of the joint and have been shown to be strongly associated with inflammation in rheumatoid arthritis (RA). Circulating MMPs have also been associated with cardiovascular disease in the general population, and are predictive of cardiovascular mortality. The purpose of the present study was to determine whether circulating levels of MMPs are predictive of mortality in RA
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Premature germination of resting spores as a means of Protecting brassica crops from Plasmodiophora brassicae Wor., (clubroot)
Premature germination of resting spores as a means of protecting brassica crops from Plasmodiphora brassicae Wor., (Clubroot). Crop Protection. Clubroot disease causes substantial yield and quality losses in broadacre oil seed and intensive vegetable brassica crops worldwide. The causal microbe Plasmodiophora brassicae Wor., perennates as soil-borne dormant resting spores. Their germination is triggered by exudates from host roots. A valuable addition to sustainable integrated control strategies could be developed by identifying and synthesising the molecules responsible for stimulating resting spore germination. This paper reports experiments in which stimulatory exudates were collected from brassica roots following exposure to infective stages of P. brassicae. Analyses identified a germination signalling molecule of circa 1 kDa formed of glucose sub-units. Mass spectral analyses showed this to be a complex hexasaccharide carbohydrate with structural similarities to the components of plant cell walls. This is the first report of a host generated hexasaccharide which is capable of stimulating the germination of resting spores of P. brassicae. The implications for environmentally benign control of clubroot are discussed briefly
Characteristics and carbon stable isotopes of fluids in the Southern Kerala granulites and their bearing on the source of CO2
Carbon dioxide-rich inclusions commonly occur in the banded charnockites and khondalites of southern Kerala as well as in the incipient charnockites formed by desiccation of gneisses along oriented zones. The combined high density fluid inclusion isochores and the range of thermometric estimates from mineral assemblages indicate entrapment pressures in the range of 5.4 to 6.1 Kbar. The CO2 equation of state barometry closely compares with the 5 plus or minus 1 Kbar estimate from mineral phases for the region. The isochores for the high density fluid inclusions in all the three rock types pass through the P-T domain recorded by phase equilibria, implying that carbon dioxide was the dominating ambient fluid species during peak metamorphic conditions. In order to constrain the source of fluids and to evaluate the mechanism of desiccation, researchers undertook detailed investigations of the carbon stable isotope composition of entrapped fluids. Researchers report here the results of preliminary studies in some of the classic localities in southern Kerala namely, Ponmudi, Kottavattom, Manali and Kadakamon
Stable isotope studies on granulites from the high grade terrain of Southern India
Fluid inclusion and petrologic characteristics of South India granulites and their bearing on the sources of metamorphic fluids are discussed. This paper served as a review and an introduction to the next paper by D. Jackson. Jackson presented carbon isotope data from gases extracted from fluid inclusions in South Indian granulites. The uniformly low Delta C-13 values (minus 10 plus or minus 2 per mil) and the greater abundance of CO2 in the incipient charnockites are suggestive of fluid influx from an externally buffered reservoir
MIXED MANTLE PROVENANCE: DIVERSE GARNET COMPOSITIONS IN POLYMICT PERIDOTITES, KAAPVAAL CRATON, SOUTH AFRICA
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