801 research outputs found
Multifunctionality in embodied agents: Three levels of neural reuse
The brain in conjunction with the body is able to adapt to new environments
and perform multiple behaviors through reuse of neural resources and transfer
of existing behavioral traits. Although mechanisms that underlie this ability
are not well understood, they are largely attributed to neuromodulation. In
this work, we demonstrate that an agent can be multifunctional using the same
sensory and motor systems across behaviors, in the absence of modulatory
mechanisms. Further, we lay out the different levels at which neural reuse can
occur through a dynamical filtering of the brain-body-environment system's
operation: structural network, autonomous dynamics, and transient dynamics.
Notably, transient dynamics reuse could only be explained by studying the
brain-body-environment system as a whole and not just the brain. The
multifunctional agent we present here demonstrates neural reuse at all three
levels.Comment: Accepted at Cognitive Science Conference, 201
The plutocratic bias in the CPI : evidence from Spain
We define the plutocratic bias as the difference between the inflation measured according to the current official CPI and a democratic index in which all households receive the same weight. (i) We estimate that during the 1990s the plutocratic bias in Spain amounts to 0.055 per cent per year, or about one third of the classical substitution bias estimated by the Boskin Commission for the U.S. (ii) We find that a 16-dimensional commodity space can be conveniently reduced to 3 dimensions, consisting of a luxury good and two necessities. The price behavior of these 3 goods provides a convincing explanation of the oscillations experimented by the plutocratic bias. (iii) Finally, the fact that the plutocratic bias is positive during this period, implies that the change in money income inequality is between 2 and 5 per cent greater than the change in real income inequality. We study the robustness of these results to the time period considered and to the definition of the group index which serves as an alternative to the CPI. We estimate that during the 1980s and the second part of the 1970s in Spain, the plutocratic bias is 0.033 and 0.239 per cent per year, respectively
The Laspeyres bias in the Spanish consumer price index
The CPI compares the cost of acquiring a reference quantity vector at current and base prices. Such reference vector is the vector of mean quantities actually bought by a reference population, whose consumption patterns are investigated during a period t prior to the index base period 0. In this paper we show that unless one takes into account the price change between these two dates, the CPI ceases to be a proper statistical price index of the Laspeyres type. Among several negative consequences, the most important is that this omission produces a bias in the measurement of inflation which we call the `Laspeyres bias.' Using Spanish data, we estimate that, e.g., from 1992 to 1998, the size of the Laspeyres bias is -0.061 per cent per year, or about 6 per cent (in absolute terms) of the positive bias estimated by the Boskin commission for the U.S., which is equal to 1.1 per cent per year. The Laspeyres bias in shorter time periods reached -0.122, and -0.108 per cent per year in 1992, and 1997, respectivel
The plutocratic gap in the CPI : evidence from Spain
The plutocratic gap is defined as the difference between the inflation measured according to the current official consumer price index (CPI) and a democratic index in which all households receive the same weight. During 1992–97, the plutocratic gap in Spain averaged 0.055 percentage points a year. Since positive and negative gaps cancel out, however, the average absolute gap is significantly larger: 0.090 percentage points a year. For the purposes of accounting for the plutocratic gap, a 53-dimensional commodity space can be conveniently reduced to two dimensions: a luxury index and a necessities index.Publicad
Optimal modularity and memory capacity of neural reservoirs
The neural network is a powerful computing framework that has been exploited
by biological evolution and by humans for solving diverse problems. Although
the computational capabilities of neural networks are determined by their
structure, the current understanding of the relationships between a neural
network's architecture and function is still primitive. Here we reveal that
neural network's modular architecture plays a vital role in determining the
neural dynamics and memory performance of the network of threshold neurons. In
particular, we demonstrate that there exists an optimal modularity for memory
performance, where a balance between local cohesion and global connectivity is
established, allowing optimally modular networks to remember longer. Our
results suggest that insights from dynamical analysis of neural networks and
information spreading processes can be leveraged to better design neural
networks and may shed light on the brain's modular organization
The Plutocratic Gap in the CPI: Evidence from Spain
The plutocratic gap is defined as the difference between the inflation measured according to the current official consumer price index (CPI) and a democratic index in which all households receive the same weight. During 1992-97, the plutocratic gap in Spain averaged 0.055 percentage points a year. Since positive and negative gaps cancel out, however, the average absolute gap is significantly larger: 0.090 percentage points a year. For the purposes of accounting for the plutocratic gap, a 53-dimensional commodity space can be conveniently reduced to two dimensions: a luxury index and a necessities index. Copyright 2003, International Monetary Fund
Distributive aspects of the quality change bias in the CPI.
This paper shows that the richer households are significantly more affected by the quality-change bias (QCB) in the CPI. The empirical analysis combines the detailed information pertaining to the size of the QCB for the US with household-specific CPIs for Spain.Plutocratic gap; Money inequality; Price index; CPI; Quality bias;
Information flow through a model of the C. elegans klinotaxis circuit
Understanding how information about external stimuli is transformed into
behavior is one of the central goals of neuroscience. Here we characterize the
information flow through a complete sensorimotor circuit: from stimulus, to
sensory neurons, to interneurons, to motor neurons, to muscles, to motion.
Specifically, we apply a recently developed framework for quantifying
information flow to a previously published ensemble of models of salt
klinotaxis in the nematode worm C. elegans. The models are grounded in the
neuroanatomy and currently known neurophysiology of the worm. The unknown model
parameters were optimized to reproduce the worm's behavior. Information flow
analysis reveals several key principles underlying how the models operate: (1)
Interneuron class AIY is responsible for integrating information about positive
and negative changes in concentration, and exhibits a strong left/right
information asymmetry. (2) Gap junctions play a crucial role in the transfer of
information responsible for the information symmetry observed in interneuron
class AIZ. (3) Neck motor neuron class SMB implements an information gating
mechanism that underlies the circuit's state-dependent response. (4) The neck
carries non-uniform distribution about changes in concentration. Thus, not all
directions of movement are equally informative. Each of these findings
corresponds to an experimental prediction that could be tested in the worm to
greatly refine our understanding of the neural circuit underlying klinotaxis.
Information flow analysis also allows us to explore how information flow
relates to underlying electrophysiology. Despite large variations in the neural
parameters of individual circuits, the overall information flow architecture
circuit is remarkably consistent across the ensemble, suggesting that
information flow analysis captures general principles of operation for the
klinotaxis circuit
The Laspeyres bias in the Spanish consumer price index.
The CPI compares the cost of acquiring a reference quantity vector at current and base prices. Such reference vector is the vector of mean quantities actually bought by a reference population, whose consumption patterns are investigated during a period tau prior to the index base period 0. This paper shows that unless the price change between these two dates is taken into account, the CPI ceases to be a proper statistical price index of the Laspeyres type. Among several negative consequences, the most important is that this omission produces a bias in the measurement of inflation: the 'Laspeyres bias'. Using Spanish data, the size of the Laspeyres bias is estimated at -0.061% per year, during 1992-1998. The Laspeyres bias in shorter time periods reached -0.122% per year in 1992, and -0.108 in 1997.
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