132,576 research outputs found
Degrees of Dowd-Type Generic Oracles
No full textAbstractFor each positive integer r, M. Dowd (1992, Inform. and Comput.96, 65–76) introduced r-generic oracles (we call them r-Dowd oracles; they are different from n-genericity of arithmetical forcing). An oracle D is r-Dowd if every r-query tautology with respect to D is forced by a polynomial-sized portion of D. We propose the study of degrees and complexity of 1-Dowd oracles. Dowd also stated that no r-Dowd oracle is recursively enumerable. However, this is false. We show, among others, the following. There exists a primitive recursive 1-Dowd oracle; For every oracle A, there exists a 1-Dowd oracle D that is Turing-equivalent to A; For every 1-Dowd oracle D, there exists a 1-Dowd oracle E such that E is polynomial time many-one-equivalent to D and E is not 2-Dowd. Problems are formulated, and analogy between the jump-operator and the operation of taking the set of 1-query tautologies is discussed
Modelling the cohort effect in CBD models using a piecewise linear approach
No full textThis paper discusses a new pattern of mortality model which is built on the form and
knowledge of the two-factor mortality model named after its designers Cairns, Blake and
Dowd (2006). This model – the CBD model – is widely used and has been extended by the
authors in a number of ways, including by the use of a cohort effect. In this paper, we
propose a range of new parsimonious approaches to model the cohort effect. Instead of
adding a cohort factor to an age-period model we model the effect by building
discontinuities into the pattern of rates within each year. The fit of the resulting models is
close to that available from the best of the CBD derivatives
A Trend-Change Extension of the Cairns-Blake-Dowd Model
No full textThis paper builds on the two-factor mortality model known as the Cairns-Blake-Dowd (CBD) model, which is used to project future mortality. It is shown that these two factors do not follow a random walk, as proposed in the original model, but that each should instead be modelled as a random fluctuation around a trend, the trend changing periodically. The paper uses statistical techniques to determine the points at which there are statistically significant changes in each trend. The frequency of change in each trend is then used to project the frequency of future changes, and the sizes of historical changes are used to project the sizes of future changes. The results are then presented as fan charts, and used to estimate the range of possible future outcomes for period life expectancies. These projections show that modelling mortality rates in this way leaves much greater uncertainty over future life expectancy in the long term
Personal Papers (MS 80-0002)
No full textLetter from L. E. Dowd to D. W. Kempner discussing the construction of a screened porch through the generous donations from members, including him
DowdSupplementalMaterial – Supplemental material for Object-Feature Binding Survives Dynamic Shifts of Spatial Attention
No full textSupplemental material, DowdSupplementalMaterial for Object-Feature Binding Survives Dynamic Shifts of Spatial Attention by Emma Wu Dowd and Julie D. Golomb in Psychological Science</p
DowdOpenPracticesDisclosure – Supplemental material for Object-Feature Binding Survives Dynamic Shifts of Spatial Attention
No full textSupplemental material, DowdOpenPracticesDisclosure for Object-Feature Binding Survives Dynamic Shifts of Spatial Attention by Emma Wu Dowd and Julie D. Golomb in Psychological Science</p
Socioeconomic disparities in the seroprevalence of cytomegalovirus infection in the US population: NHANES III
No full texthttp://deepblue.lib.umich.edu/bitstream/2027.42/61298/1/Dowd,Socioeconomicdisparitiesintheseroprevalenceofcytomegalovirus.pd
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