The Determinants of GNMA Prepayments: A Pool-by-Pool Analysis

This study examines GNMA prepayment determinants as a function of interest-rate factors and the pure aging effect. While we find both interest-rate and age factors to be important, these relationships are not constant across different pools. This suggests that prepayment forecasts need to be made on a pool-by-pool basis. The study also documents a lagged relationship between changing interest rates and prepayment experience, suggesting that the prepayment decision date is made many months before the prepayment recording date.

What makes a good induction supporter?

The Teacher Induction Scheme, introduced in 2002, marked the first major change to new teacher induction in Scotland in 37 years. This paper gives an outline of these changes set against developments in mentoring theory in the wider context. It argues that the personal qualities of the induction supporter are crucial to developing an effective mentoring relationship. The views of student teachers are used to describe preferred characteristics of effective mentors and effective induction provision. A person specification is created by the comments of the "Class of 2002" — the first probationer teachers to have taken part in the Scheme

Reporting and Reparations: News Coverage and the Decision to Compensate the Forcefully Sterilized in North Carolina

Forced sterilization was an accepted legal practice in the United States during the beginning and middle of the previous century. It was promoted by an international movement to prevent procreation by those deemed unworthy of reproduction (Black, 2003). North Carolina has recently decided to pay reparations to forced sterilization victims (Editorial (Winston-Salem Journal), 2013) and the state of Virginia has more recently emulated this decision (Martz & Nolan 2015). This analysis will discuss the common eugenic history of many states but will also highlight North Carolina’s distinctiveness on this issue. The qualitative portion of the analysis will explain the historical reasons North Carolina would be likely to be the first state to adopt this policy. Our quantitative analysis will examine the role of news coverage of sterilization policy in North Carolina and its relationship to the decision to adopt a policy of reparations

The nature of assembly bias - I. Clues from a LCDM cosmology

We present a new proxy for the overdensity peak height for which the large-scale clustering of haloes of a given mass does not vary significantly with the assembly history. The peak height, usually taken to be well represented by the virial mass, can instead be approximated by the mass inside spheres of different radii, which in some cases can be larger than the virial radius and therefore include mass outside the individual host halo. The sphere radii are defined as r = $a$ delta_t + $b$ log_10(M_vir/M_nl), where delta_t is the age relative to the typical age of galaxies hosted by haloes with virial mass M_vir, M_nl is the non-linear mass, and $a$=0.2 and $b$=-0.02 are the free parameters adjusted to trace the assembly bias effect. Note that $r$ depends on both halo mass and age. In this new approach, some of the objects which were initially considered low-mass peaks belong to regions with higher overdensities. At large scales, i.e. in the two-halo regime, this model properly recovers the simple prescription where the bias responds to the height of the mass peak alone, in contrast to the usual definition (virial mass) that shows a strong dependence on additional halo properties such as formation time. The dependence on the age in the one-halo term is also remarkably reduced. The population of galaxies whose "peak height" changes with this new definition consists mainly of old stellar populations and are preferentially hosted by low-mass haloes located near more massive objects. The latter is in agreement with recent results which indicate that old, low-mass haloes would suffer truncation of mass accretion by nearby larger haloes or simply due to the high density of their surroundings, thus showing an assembly bias effect. The change in mass is small enough that the Sheth et al. (2001) mass function is still a good fit to the resulting distribution of new masses.Comment: 13 pages, 10 figures, submitted to MNRAS, comments welcom

Does the process map influence the outcome of quality improvement work? A comparison of a sequential flow diagram and a hierarchical task analysis diagram

Background: Many quality and safety improvement methods in healthcare rely on a complete and accurate map of the process. Process mapping in healthcare is often achieved using a sequential flow diagram, but there is little guidance available in the literature about the most effective type of process map to use. Moreover there is evidence that the organisation of information in an external representation affects reasoning and decision making. This exploratory study examined whether the type of process map - sequential or hierarchical - affects healthcare practitioners' judgments.Methods: A sequential and a hierarchical process map of a community-based anti coagulation clinic were produced based on data obtained from interviews, talk-throughs, attendance at a training session and examination of protocols and policies. Clinic practitioners were asked to specify the parts of the process that they judged to contain quality and safety concerns. The process maps were then shown to them in counter-balanced order and they were asked to circle on the diagrams the parts of the process where they had the greatest quality and safety concerns. A structured interview was then conducted, in which they were asked about various aspects of the diagrams.Results: Quality and safety concerns cited by practitioners differed depending on whether they were or were not looking at a process map, and whether they were looking at a sequential diagram or a hierarchical diagram. More concerns were identified using the hierarchical diagram compared with the sequential diagram and more concerns were identified in relation to clinical work than administrative work. Participants' preference for the sequential or hierarchical diagram depended on the context in which they would be using it. The difficulties of determining the boundaries for the analysis and the granularity required were highlighted.Conclusions: The results indicated that the layout of a process map does influence perceptions of quality and safety problems in a process. In quality improvement work it is important to carefully consider the type of process map to be used and to consider using more than one map to ensure that different aspects of the process are captured

Understanding the relationship between alcohol outlet density and life expectancy in Baltimore City: The role of community violence and community disadvantage

This research investigated the relationship between alcohol outlet density (AOD) and life expectancy, as mediated by community violence and community disadvantage. We used linear regression models to assess bivariate and multivariate relationships. There was a negative bivariate association between liquor store density and average life expectancy (β = â 7.3370, p < 0.001). This relationship was partially attenuated when controlling for community disadvantage and fully attenuated when controlling for community violence. Bars/taverns (i.e., onâ premise) were not associated with average life expectancy (β = â 0.589, p = 0.220). Liquor store density is associated with higher levels of community disadvantage and higher rates of violence, both of which are associated with lower life expectancies. Future research, potential intervention, and current related policies are discussed.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146620/1/jcop22099_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146620/2/jcop22099.pd

Resonant relaxation and the warp of the stellar disc in the Galactic centre

Observations of the spatial distribution and kinematics of young stars in the Galactic centre can be interpreted as showing that the stars occupy one, or possibly two, discs of radii ~0.05-0.5 pc. The most prominent (`clockwise') disc exhibits a strong warp: the normals to the mean orbital planes in the inner and outer third of the disc differ by ~60 deg. Using an analytical model based on Laplace-Lagrange theory, we show that such warps arise naturally and inevitably through vector resonant relaxation between the disc and the surrounding old stellar cluster.Comment: 24 pages, 8 figures, accepted by MNRA

Flow-Driven Cloud Formation and Fragmentation: Results From Eulerian and Lagrangian Simulations

The fragmentation of shocked flows in a thermally bistable medium provides a natural mechanism to form turbulent cold clouds as precursors to molecular clouds. Yet because of the large density and temperature differences and the range of dynamical scales involved, following this process with numerical simulations is challenging. We compare two-dimensional simulations of flow-driven cloud formation without self-gravity, using the Lagrangian Smoothed Particle Hydrodynamics (SPH) code VINE and the Eulerian grid code Proteus. Results are qualitatively similar for both methods, yet the variable spatial resolution of the SPH method leads to smaller fragments and thinner filaments, rendering the overall morphologies different. Thermal and hydro-dynamical instabilities lead to rapid cooling and fragmentation into cold clumps with temperatures below 300K. For clumps more massive than 1 Msun/pc, the clump mass function has an average slope of -0.8. The internal velocity dispersion of the clumps is nearly an order of magnitude smaller than their relative motion, rendering it subsonic with respect to the internal sound speed of the clumps, but supersonic as seen by an external observer. For the SPH simulations most of the cold gas resides at temperatures below 100K, while the grid-based models show an additional, substantial component between 100 and 300K. Independently of the numerical method our models confirm that converging flows of warm neutral gas fragment rapidly and form high-density, low-temperature clumps as possible seeds for star formation.Comment: 9 pages, 8 figures, MNRAS accepte