32,179 research outputs found
Splitting of liftings in products of probability spaces
We prove that if (X,\mathfrakA,P) is an arbitrary probability space with
countably generated \sigma-algebra \mathfrakA, (Y,\mathfrakB,Q) is an arbitrary
complete probability space with a lifting \rho and \hat R is a complete
probability measure on \mathfrakA \hat \otimes_R \mathfrakB determined by a
regular conditional probability {S_y:y\in Y} on \mathfrakA with respect to
\mathfrakB, then there exist a lifting \pi on (X\times Y,\mathfrakA \hat
\otimes_R \mathfrakB,\hat R) and liftings \sigma_y on (X,\hat \mathfrakA_y,\hat
S_y), y\in Y, such that, for every E\in\mathfrakA \hat \otimes_R \mathfrakB and
every y\in Y, [\pi(E)]^y=\sigma_y\bigl([\pi(E)]^y\bigr). Assuming the absolute
continuity of R with respect to P\otimes Q, we prove the existence of a regular
conditional probability {T_y:y\in Y} and liftings \varpi on (X\times
Y,\mathfrakA \hat \otimes_R \mathfrakB,\hat R), \rho' on (Y,\mathfrakB,\hat Q)
and \sigma_y on (X,\hat \mathfrakA_y,\hat S_y), y\in Y, such that, for every
E\in\mathfrakA \hat \otimes_R \mathfrakB and every y\in Y,
[\varpi(E)]^y=\sigma_y\bigl([\varpi(E)]^y\bigr) and \varpi(A\times
B)=\bigcup_{y\in\rho'(B)}\sigma_y(A)\times{y}\qquadif A\times
B\in\mathfrakA\times\mathfrakB. Both results are generalizations of Musia\l,
Strauss and Macheras [Fund. Math. 166 (2000) 281-303] to the case of measures
which are not necessarily products of marginal measures. We prove also that
liftings obtained in this paper always convert \hat R-measurable stochastic
processes into their \hat R-measurable modifications.Comment: Published at http://dx.doi.org/10.1214/009117904000000018 in the
Annals of Probability (http://www.imstat.org/aop/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The long-run relationship between consumption and housing wealth in the Eighth District states
Federal Reserve District, 8th ; Consumption (Economics) ; Housing
Forecasting real housing price growth in the Eighth District states
The authors consider forecasting real housing price growth for the individual states of the Federal Reserve's Eighth District. They first analyze the forecasting ability of a large number of potential predictors of state real housing price growth using an autoregressive distributed lag (ARDL) model framework. A number of variables, including the state housing price-to-income ratio, state unemployment rate, and national inflation rate, appear to provide information that is useful for forecasting real housing price growth in many Eighth District states. Given that it is typically difficult to determine a priori the particular variable or small set of variables that are the most relevant for forecasting real housing price growth for a given state and time period, the authors also consider various methods for combining the individual ARDL model forecasts. They find that combination forecasts are quite helpful in generating accurate forecasts of real housing price growth in the individual Eighth District states.Housing - Prices ; Federal Reserve District, 8th
On Necessary and Sufficient Conditions for Preserving Convergence Rates to Equilibrium in Deterministically and Stochastically Perturbed Differential Equations with Regularly Varying Nonlinearity
This paper develops necessary and sufficient conditions for the preservation
of asymptotic convergence rates of deterministically and stochastically
perturbed ordinary differential equations with regularly varying nonlinearity
close to their equilibrium. Sharp conditions are also established which
preserve the asymptotic behaviour of the derivative of the underlying
unperturbed equation. Finally, necessary and sufficient conditions are
established which enable finite difference approximations to the derivative in
the stochastic equation to preserve the asymptotic behaviour of the derivative
of the unperturbed equation, even though the solution of the stochastic
equation is nowhere differentiable, almost surely
Probing the Ionization State of the Universe at z>6
We present high signal-to-noise ratio Keck ESI spectra of the two quasars
known to have Gunn-Peterson absorption troughs, SDSS J1030+0524 (z=6.28) and
SDSS J1148+5251 (z=6.37). The Ly alpha and Ly beta troughs for SDSS J1030+0524
are very black and show no evidence for any emission over a redshift interval
of ~0.2 starting at z=6. On the other hand, SDSS J1148+5251 shows a number of
emission peaks in the Ly beta Gunn-Peterson trough along with a single weak
peak in the Ly alpha trough. The Ly alpha emission has corresponding Ly beta
emission, suggesting that it is indeed a region of lower optical depth in the
intergalactic medium at z=6.08.
The stronger Ly beta peaks in the spectrum of SDSS J1148+5251 could
conceivably also be the result of "leaks" in the IGM, but we suggest that they
are instead Ly alpha emission from an intervening galaxy at z=4.9. This
hypothesis gains credence from a strong complex of C IV absorption at the same
redshift and from the detection of continuum emission in the Ly alpha trough at
the expected brightness. If this proposal is correct, the quasar light has
probably been magnified through gravitational lensing by the intervening
galaxy. The Stromgren sphere observed in the absorption spectrum of SDSS
J1148+5251 is significantly smaller than expected based on its brightness,
which is consistent with the hypothesis that the quasar is lensed.
If our argument for lensing is correct, the optical depths derived from the
troughs of SDSS J1148+5251 are only lower limits (albeit still quite strong,
with tau(LyA)>16 inferred from the Ly beta trough.) The Ly beta absorption
trough of SDSS J1030+0524 gives the single best measurement of the IGM
transmission at z>6, with an inferred optical depth tau(LyA)>22.Comment: To appear in July 2003 AJ, 34 pages, 11 figures; minor changes/typos
fixe
The Geoff Egan Memorial Lecture 2011. Artefacts, art and artifice: reconsidering iconographic sources for archaeological objects in early modern Europe
A first systematic analysis of historic domestic material culture depicted in contemporaneous Western painting and prints, c.1400-1800. Drawing on an extensive data set, the paper proposes to methodologies and hermeneutics for historical analysis and archaeological correspondence
- …