MEXIT: Maximal un-coupling times for stochastic processes

Classical coupling constructions arrange for copies of the \emph{same} Markov process started at two \emph{different} initial states to become equal as soon as possible. In this paper, we consider an alternative coupling framework in which one seeks to arrange for two \emph{different} Markov (or other stochastic) processes to remain equal for as long as possible, when started in the \emph{same} state. We refer to this "un-coupling" or "maximal agreement" construction as \emph{MEXIT}, standing for "maximal exit". After highlighting the importance of un-coupling arguments in a few key statistical and probabilistic settings, we develop an explicit \MEXIT construction for stochastic processes in discrete time with countable state-space. This construction is generalized to random processes on general state-space running in continuous time, and then exemplified by discussion of \MEXIT for Brownian motions with two different constant drifts.Comment: 28 page

Preparations for Independence and Financial Security in Later Life: A Conceptual Framework and Application to Canada

In this paper, we develop a conceptual framework to describe an individual's preparations for later life. Situated in the life course perspective, this provides a framework that invites a more comprehensive and systematic study of preparations for later life. It describes a dynamic process that portrays the interplay between social structure and human agency. Through its consideration of collective preparations (the public protection programs offered by the state), individual preparations (financial and non- financial), and the interplay between the two, this framework provides fresh insight into the existing literature on retirement planning, the timing of retirement, savings, and consumption behaviour in later life. Moreover, the model may be used to structure research questions, to guide policy decision making and to point the direction for the design and content of future research studies. While the purpose of this paper is primarily the development of a conceptual model, we draw on empirical examples from the 1991 Survey of Aging and Independence (SAI) to illustrate some aspects of the model to Canada. We conclude by suggesting a number of research and questions that may be generated from the model.retirement planning; savings; SAI

A survey thesis of the personal reading preferences of children in the intermediate grades

Thesis (Ed.M.)--Boston Universit

Thermal inactivation of Byssochlamys nivea in pineapple nectar combined with preliminary high pressure treatments

Byssochlamys nivea is a thermal resistant filamentous fungi and potential micotoxin producer. Recent studies have verified the presence of ascospores of such microorganism in samples of pineapple nectars. Although the majority of filamentous fungi have limited heat resistance and are easily destroyed by heat, Byssochlamys nivea ascospores have shown high thermal resistance. The aim of this work was to evaluate the application of linear and Weibull models on thermal inactivation (70, 80 and 90ºC) of Byssochlamys nivea ascospores in pineapple nectar after pretreatment with high pressure (550MPa or 650MPa during 15min). Following the treatments, survival curves were built up for each processing temperature and adjusted for both models. It was observed that survival curves at 90°C after high pressure pretreatment at 550 MPa/15 min did not fit well to linear and Weibull models. For all the other treatments, the Weibull model presented a better fit. At 90ºC without pressure treatment, the Weibull model also showed a better adjustment, having a larger R2 and a smaller RMSE. Regarding the process effectiveness, a 5-log reduction (t5), as recommended for pasteurization, was only achieved for Byssochlamys nivea ascospores presented in pineapple nectar at 90ºC/10.7 min with previous high pressure treatment of 650 MPa for 15 min. Considering the high intensity and energy demanding process with possibly product damage, other preventive and alternative treatments are being investigated

Secondary Markets, Risk, and Access to Credit Evidence from the Mortgage Market

Secondary markets for credit are widely believed to improve efficiency and increase access to credit. In part, this is because of their greater ability to manage risk. However, the degree to which secondary markets expand access to credit is virtually unknown. Using the mortgage market as an example, we begin to fill that gap. Our conceptual model suggests that secondary credit markets have potentially ambiguous effects on interest rates, but unambiguous positive effects on the number of loans issued. We focus our empirical analysis on the latter using 1992-2004 HMDA files for conventional, conforming, home purchase loans in conjunction with Census tract data

Homeownership Boom and Bust 2000 to 2009: Where Will the Homeownership Rate Go from Here?

The increase in the homeownership rate in the middle of the last decade extended to all age groups but was most pronounced among individuals under age 30. These increases coincided with looser credit conditions that enhanced household access to mortgage credit along with evidence of less risk averse attitudes towards investment in homeownership. Following the crash, these trends have reversed and homeownership rates have largely reverted back to the levels of 2000. The drop in the homeownership rate from an all-time high of 69.2 in 2004 to 66.4 percent in the first quarter of 2011 reflects a decline from unsustainable levels to something closer to historical averages, and while the homeownership rate may have bottomed out, it could fall another one or two percentage points due to tightened credit and other factors

Do the GSEs Expand the Supply of Mortgage Credit? New Evidence of Crowd Out in the Secondary Mortgage Market

The dramatic government takeover of Fannie Mae and Freddie Mac in September, 2008 was motivated in part by a desire to ensure a continued flow of credit to the mortgage market. This study examines a closely related issue: the extent to which GSE activity crowds out mortgage purchases by private secondary market intermediaries. Evidence of substantial crowd out suggests that government support for the GSEs may be less warranted, whereas the absence of crowd out implies that GSE loan purchases enhance liquidity.Using 1994-2008 HMDA data for conventional, conforming sized loans, three distinct periods with regard to GSE crowd out are apparent. From 1994-2003, the share of loans sold to the secondary market increased from 60 to over 90 percent, private sector and GSE market shares of loan purchases were roughly similar for most market segments, and IV estimates indicate relatively little GSE crowd out of private secondary market purchases. From 2004 to 2006, private loan purchases boomed and dominated those of the GSEs, while IV estimates indicate crowd out jumped to 50 percent at the peak of the boom. This is especially true in the market for home purchase as opposed to refinance loans. With the crash in housing and mortgage markets in 2007, private sector intermediaries pulled back, the GSEs regained market share, and evidence of GSE crowd out disappeared in both the home purchase loan and refinance markets. These patterns suggest that the degree of GSE crowd out varies with market conditions and that the federal takeover of Fannie Mae and Freddie Mac likely served to enhance liquidity to the mortgage market during the 2007-2009 financial crisis