7,431 research outputs found
Nonlinear elastic polymers in random flow
Polymer stretching in random smooth flows is investigated within the
framework of the FENE dumbbell model. The advecting flow is Gaussian and
short-correlated in time. The stationary probability density function of
polymer extension is derived exactly. The characteristic time needed for the
system to attain the stationary regime is computed as a function of the
Weissenberg number and the maximum length of polymers. The transient relaxation
to the stationary regime is predicted to be exceptionally slow in the proximity
of the coil-stretch transition.Comment: 10 pages, to be published in J. Fluid Mec
Renormalized transport of inertial particles in surface flows
Surface transport of inertial particles is investigated by means of the
perturbative approach, introduced by Maxey (J. Fluid Mech. 174, 441 (1987)),
which is valid in the case the deflections induced on the particle trajectories
by the fluid flow can be considered small. We consider a class of compressible
random velocity fields, in which the effect of recirculations is modelled by an
oscillatory component in the Eulerian time correlation profile. The main issue
we address here is whether fluid velocity fluctuations, in particular the
effect of recirculation, may produce nontrivial corrections to the streaming
particle velocity. Our result is that a small (large) degree of recirculation
is associated with a decrease (increase) of streaming with respect to a
quiescent fluid. The presence of this effect is confirmed numerically, away
from the perturbative limit. Our approach also allows us to calculate the
explicit expression for the eddy diffusivity, and to compare the efficiency of
diffusive and ballistic transport.Comment: 18 pages, 13 figures, submitted to JF
The Macroeconomic Effects of Fiscal Policy in Portugal: a Bayesian SVAR Analysis
In the last twenty years Portugal struggled to keep public finances under control, notably in containing primary spending. We use a new quarterly dataset covering 1979:1-2007:4, and estimate a Bayesian Structural Autoregression model to analyze the macroeconomic effects of fiscal policy. The results show that positive government spending shocks, in general, have a negative effect on real GDP; lead to important âcrowding-outâ effects, by impacting negatively on private consumption and investment; and have a persistent and positive effect on the price level and the average cost of financing government debt. Positive government revenue shocks tend to have a negative impact on GDP; and lead to a fall in the price level. The evidence also shows the importance of explicitly considering the government debt dynamics in the model. Finally, a VAR counter-factual exercise confirms that unexpected positive government spending shocks lead to important âcrowding-outâ effects..B-SVAR, fiscal policy, debt dynamics, Portugal.
Assessing Long-Term Fiscal Developments: Evidence from Portugal
Drawing on quarterly data for Portugal, we use a Three-Stage Least Square method and a system of equations to recursively estimate two components of fiscal policy â responsiveness and persistence â and to infer about the sources of fiscal deterioration (improvement). The results suggest that: (i) government spending exhibits higher persistence than government revenue; and (ii) government revenue is more responsive to the business cycle than government spending.Fiscal deterioration; Portugal.
The Macroeconomic Effects of Fiscal Policy
We investigate the macroeconomic effects of fiscal policy using a Bayesian Structural Vector Autoregression approach. We build on a recursive identification scheme, but we: (i) include the feedback from government debt (ii); look at the impact on the composition of output; (iii) assess the effects on asset markets (via housing and stock prices); (iv) add the exchange rate; (v) assess potential interactions between fiscal and monetary policy; (vi) use quarterly data, particularly, fiscal data; and (vii) analyze empirical evidence from the U.S., the U.K., Germany, and Italy. The results show that government spending shocks, in general, have a small effect on GDP; lead to important âcrowding-outâ effects; have a varied impact on housing prices and generate a quick fall in stock prices; and lead to a depreciation of the real effective exchange rate. Government revenue shocks generate a small and positive effect on both housing prices and stock prices that later mean reverts; and lead to an appreciation of the real effective exchange rate. The empirical evidence also shows that it is important to explicitly consider the government debt dynamics in the model.fiscal policy; Bayesian Structural VAR; debt dynamics.
The Macroeconomic Effects of Fiscal Policy
We investigate the macroeconomic effects of fiscal policy using a Bayesian Structural Vector Autoregression approach. We build on a recursive identification scheme, but we: (i) include the feedback from government debt (ii); look at the impact on the composition of output; (iii) assess the effects on asset markets (via housing and stock prices); (iv) add the exchange rate; (v) assess potential interactions between fiscal and monetary policy; (vi) use quarterly data, particularly, fiscal data; and (vii) analyze empirical evidence from the U.S., the U.K., Germany, and Italy. The results show that government spending shocks, in general, have a small effect on GDP; lead to important âcrowding-outâ effects; have a varied impact on housing prices and generate a quick fall in stock prices; and lead to a depreciation of the real effective exchange rate. Government revenue shocks generate a small and positive effect on both housing prices and stock prices that later mean reverts; and lead to an appreciation of the real effective exchange rate. The empirical evidence also shows that it is important to explicitly consider the government debt dynamics in the model.fiscal policy, Bayesian Structural VAR, debt dynamics.
Consumption, Wealth, Stock and Government Bond Returns: International Evidence
In this paper, we show, from the consumerâs budget constraint, that the residuals of the trend relationship among consumption, aggregate wealth, and labour income should predict both stock returns and government bond yields. We use data for several OECD countries and find that when agents expect future stock returns to be higher, they will temporarily allow consumption to rise. Regarding government bond yields, when bonds are seen as a component of asset wealth, then investors react in the same way. If, however, the increase in the yields is perceived as signalling a future rise in taxes, then they will temporarily reduce their consumption.consumption, wealth, stock returns, bond returns.
Fiscal Policy, Housing and Stock Prices
This paper investigates the link between fiscal policy shocks and movements in asset markets using a Fully Simultaneous System approach in a Bayesian framework. Building on the works of Blanchard and Perotti (2002), Leeper and Zha (2003), and Sims and Zha (1999, 2006), the empirical evidence for the U.S., the U.K., Germany, and Italy shows that it is important to explicitly consider the government debt dynamics when assessing the macroeconomic effects of fiscal policy and its impact on asset markets. In addition, the results from a VAR counter-factual exercise suggest that: (i) fiscal policy shocks play a minor role in the asset markets of the U.S. and Germany; (ii) they substantially increase the variability of housing and stock prices in the U.K..; and (iii) government revenue shocks have apparently contributed to an increase of volatility in Italy.Bayesian Structural VAR; fiscal policy; housing prices; stock prices.
Consumption, Wealth, Stock and Government Bond Returns: International Evidence
In this paper, we show, from the consumerâs budget constraint, that the residuals of the trend relationship among consumption, aggregate wealth, and labour income should predict both stock returns and government bond yields. We use data for several OECD countries and find that when agents expect future stock returns to be higher, they will temporarily allow consumption to rise. Regarding government bond yields, when bonds are seen as a component of asset wealth, then investors react in the same way. If, however, the increase in the yields is perceived as signalling a future rise in taxes, then they will temporarily reduce their consumption.consumption, wealth, stock returns, bond returns.
The Macroeconomic Effects of Fiscal Policy in Portugal: a Bayesian SVAR Analysis
In the last twenty years Portugal struggled to keep public finances under control, notably in containing primary spending. We use a new quarterly dataset covering 1979:1-2007:4, and estimate a Bayesian Structural Autoregression model to analyze the macroeconomic effects of fiscal policy. The results show that positive government spending shocks, in general, have a negative effect on real GDP; lead to important "crowding-out" effects, by impacting negatively on private consumption and investment; and have a persistent and positive effect on the price level and the average cost of financing government debt. Positive government revenue shocks tend to have a negative impact on GDP; and lead to a fall in the price level. The evidence also shows the importance of explicitly considering the government debt dynamics in the model. Finally, a VAR counter-factual exercise confirms that unexpected positive government spending shocks lead to important "crowding-out" effects.B-SVAR, fiscal policy, debt dynamics, Portugal.
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