8,411 research outputs found
Stimulating Critical Literacy Consciousness
This story from the field recounts how, after being an educator for over ten years, I became aware that I had been responsible for misrepresenting information to my first-grade students. This difficult realization shook me to the core, but it also became the impetus for me to learn about critical pedagogy and critical literacy. Both of these educational practices align with my faith and have been transformational to my teaching. As a result, I am able to teach my pre-service and graduate students how to instruct in more socially-just ways
Decay of Correlations in Fermi Systems at Non-zero Temperature
The locality of correlation functions is considered for Fermi systems at
non-zero temperature. We show that for all short-range, lattice Hamiltonians,
the correlation function of any two fermionic operators decays exponentially
with a correlation length which is of order the inverse temperature for small
temperature. We discuss applications to numerical simulation of quantum systems
at non-zero temperature.Comment: 3 pages, 0 figure
How Financial Literacy and Impatience Shape Retirement Wealth and Investment Behaviors
Two competing explanations for why consumers have trouble with financial decisions are gaining momentum. One is that people are financially illiterate since they lack understanding of simple economic concepts and cannot carry out computations such as computing compound interest, which could cause them to make suboptimal financial decisions. A second is that impatience or present-bias might explain suboptimal financial decisions. That is, some people persistently choose immediate gratification instead of taking advantage of larger long-term payoffs. We use experimental evidence from Chile to explore how these factors appear related to poor financial decisions. Our results show that our measure of impatience is a strong predictor of wealth and investment in health. Financial literacy is also correlated with wealth though it appears to be a weaker predictor of sensitivity to framing in investment decisions. Policymakers interested in enhancing retirement well-being would do well to consider the importance of these factors.
A short proof of stability of topological order under local perturbations
Recently, the stability of certain topological phases of matter under weak
perturbations was proven. Here, we present a short, alternate proof of the same
result. We consider models of topological quantum order for which the
unperturbed Hamiltonian can be written as a sum of local pairwise
commuting projectors on a -dimensional lattice. We consider a perturbed
Hamiltonian involving a generic perturbation that can be written
as a sum of short-range bounded-norm interactions. We prove that if the
strength of is below a constant threshold value then has well-defined
spectral bands originating from the low-lying eigenvalues of . These bands
are separated from the rest of the spectrum and from each other by a constant
gap. The width of the band originating from the smallest eigenvalue of
decays faster than any power of the lattice size.Comment: 15 page
Joint deprojection of Sunyaev-Zeldovich and X-ray images of galaxy clusters
We present two non-parametric deprojection methods aimed at recovering the
three-dimensional density and temperature profiles of galaxy clusters from
spatially resolved thermal Sunyaev-Zeldovich (tSZ) and X-ray surface brightness
maps, thus avoiding the use of X-ray spectroscopic data. In both methods,
clusters are assumed to be spherically symmetric and modeled with an onion-skin
structure. The first method follows a direct geometrical approach. The second
method is based on the maximization of a single joint (tSZ and X-ray)
likelihood function, which allows one to fit simultaneously the two signals by
following a Monte Carlo Markov Chain approach. These techniques are tested
against a set of cosmological simulations of clusters, with and without
instrumental noise. We project each cluster along the three orthogonal
directions defined by the principal axes of the momentum of inertia tensor.
This enables us to check any bias in the deprojection associated to the cluster
elongation along the line of sight. After averaging over all the three
projection directions, we find an overall good reconstruction, with a small
(<~10 per cent) overestimate of the gas density profile. This turns into a
comparable overestimate of the gas mass within the virial radius, which we
ascribe to the presence of residual gas clumping. Apart from this small bias
the reconstruction has an intrinsic scatter of about 5 per cent, which is
dominated by gas clumpiness. Cluster elongation along the line of sight biases
the deprojected temperature profile upwards at r<~0.2r_vir and downwards at
larger radii. A comparable bias is also found in the deprojected temperature
profile. Overall, this turns into a systematic underestimate of the gas mass,
up to 10 percent. (Abridged)Comment: 17 pages, 15 figures, accepted by MNRA
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