4,203 research outputs found
Targeting the Poor: A Macroeconomic Analysis of Cash Transfer Programs
This paper introduces cash transfers targeting the poor in an incomplete marketsmodel with heterogeneous agents facing idiosyncratic risk. These transfers change thedegree of insurance in the economy and a ect precautionary motives asymmetrically,leading the poorest households to decrease savings proportionally more than theirricher counterparts. In a model economy calibrated to Brazil, once the cash transferprogram is adopted, wealth inequality and social welfare increase, poverty decreases,while employment and income inequality remain about the same. Imperfect access to nancial markets is important for these results, whereas whether the program is fundedwith lump sum or distortive taxes is not.
On the origins of scaling corrections in ballistic growth models
We study the ballistic deposition and the grain deposition models on
two-dimensional substrates. Using the Kardar-Parisi-Zhang (KPZ) ansatz for
height fluctuations, we show that the main contribution to the intrinsic width,
which causes strong corrections to the scaling, comes from the fluctuations in
the height increments along deposition events. Accounting for this correction
in the scaling analysis, we obtained scaling exponents in excellent agreement
with the KPZ class. We also propose a method to suppress these corrections,
which consists in divide the surface in bins of size and use only
the maximal height inside each bin to do the statistics. Again, scaling
exponents in remarkable agreement with the KPZ class were found. The binning
method allowed the accurate determination of the height distributions of the
ballistic models in both growth and steady state regimes, providing the
universal underlying fluctuations foreseen for KPZ class in 2+1 dimensions. Our
results provide complete and conclusive evidences that the ballistic model
belongs to the KPZ universality class in dimensions. Potential
applications of the methods developed here, in both numerics and experiments,
are discussed.Comment: 8 pages, 7 figure
Tunneling spectra of layered strongly correlated d-wave superconductors
Tunneling conductance experiments on cuprate superconductors exhibit a large
diversity of spectra that appear in different nano-sized regions of
inhomogeneous samples. In this letter, we use a mean-field approach to the
tt't''J model in order to address the features in these spectra that deviate
from the BCS paradigm, namely, the bias sign asymmetry at high bias, the
generic lack of evidence for the Van Hove singularity, and the occasional
absence of coherence peaks. We conclude that these features can be reproduced
in homogeneous layered d-wave superconductors solely due to a proximate Mott
insulating transition. We also establish the connection between the above
tunneling spectral features and the strong renormalization of the electron
dispersion around (0,pi) and (pi,0) and the momentum space anisotropy of
electronic states observed in ARPES experiments.Comment: 4 pages, 3 figures. Added comment on the role of sample
inhomogeneity. Published version. Homepage http://dao.mit.edu/~wen
Static and dynamic properties of vortices in anisotropic magnetic disks
We investigate the effect of the magnetic anisotropy () on the static
and dynamic properties of magnetic vortices in small disks. Our micromagnetic
calculations reveal that for a range of there is an enlargement of the
vortex core. We analyze the influence of on the dynamics of the vortex
core magnetization reversal under the excitation of a pulsed field. The
presence of , which leads to better resolved vortex structures, allows us
to discuss in more details the role played by the in-plane and perpendicular
components of the gyrotropic field during the vortex-antivortex nucleation and
annihilation.Comment: 4 pages, 4 figure
- …