162 research outputs found
New evidence on cyclical and structural sources of unemployment
We provide cross-country evidence on the relative importance of cyclical and structural factors in explaining unemployment, including the sharp rise in U.S. long-term unemployment during the Great Recession of 2007-09. About 75% of the forecast error variance of unemployment is accounted for by cyclical factors—real GDP changes (“Okun’s Law”), monetary and fiscal policies, and the uncertainty effects emphasized by Bloom (2009). Structural factors, which we measure using the dispersion of industry-level stock returns, account for the remaining 25 percent. For U.S. long-term unemployment the split between cyclical and structural factors is closer to 60-40, including during the Great Recession.Unemployment
ReProHRL: Towards Multi-Goal Navigation in the Real World using Hierarchical Agents
Robots have been successfully used to perform tasks with high precision. In
real-world environments with sparse rewards and multiple goals, learning is
still a major challenge and Reinforcement Learning (RL) algorithms fail to
learn good policies. Training in simulation environments and then fine-tuning
in the real world is a common approach. However, adapting to the real-world
setting is a challenge. In this paper, we present a method named Ready for
Production Hierarchical RL (ReProHRL) that divides tasks with hierarchical
multi-goal navigation guided by reinforcement learning. We also use object
detectors as a pre-processing step to learn multi-goal navigation and transfer
it to the real world. Empirical results show that the proposed ReProHRL method
outperforms the state-of-the-art baseline in simulation and real-world
environments in terms of both training time and performance. Although both
methods achieve a 100% success rate in a simple environment for single
goal-based navigation, in a more complex environment and multi-goal setting,
the proposed method outperforms the baseline by 18% and 5%, respectively. For
the real-world implementation and proof of concept demonstration, we deploy the
proposed method on a nano-drone named Crazyflie with a front camera to perform
multi-goal navigation experiments.Comment: AAAI 2023 RL Ready for Production Worksho
Impact of the equation of state on - and - mode oscillations of neutron stars
We investigate the impact of the neutron-star matter equation of state on the
- and -mode oscillations of neutron stars obtained within the Cowling
approximation and linearized general relativity. The - and -mode
oscillation frequencies, and their damping times are calculated using
representative sets of Skyrme Hartree-Fock and relativistic mean-field models,
all of which reproduce nuclear systematics and support neutron
stars. Our study shows strong correlations between the frequencies of - and
-modes and their damping times with the pressure of -equilibrated
matter at densities equal to or slightly higher than the nuclear saturation
density . Such correlations are found to be almost independent of the
composition of the stars. The frequency of the -mode of star
is strongly correlated with the slope of the symmetry energy and
-equilibrated pressure at density . Compared to GR calculations,
the error in the Cowling approximation for the -mode is about 30\% for
neutron stars of low mass, whereas it decreases with increasing mass. The
accuracy of the -mode is better than 15\% for neutron stars of maximum
mass, and improves for lower masses and higher number of radial nodes.Comment: Comments are welcom
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