57 research outputs found
A string dual for partially topological Chern-Simons-matter theories
We consider a string dual of a partially topological
Chern-Simons-matter (PTCSM) theory recently introduced by Aganagic, Costello,
McNamara and Vafa. In this theory, fundamental matter fields are coupled to the
Chern-Simons theory in a way that depends only on a transverse holomorphic
structure on a manifold; they are not fully dynamical, but the theory is also
not fully topological. One description of this theory arises from topological
strings on the deformed conifold with Lagrangian 3-branes and
additional coisotropic `flavor' 5-branes. Applying the idea of the
Gopakumar-Vafa duality to this setup, we suggest that this has a dual
description as a topological string on the resolved conifold , in the
presence of coisotropic 5-branes. We test this duality by computing the annulus
amplitude on the deformed conifold and the disc amplitude on the resolved
conifold via equivariant localization, and we find an agreement between the
two. We find a small discrepancy between the topological string results and the
large limit of the partition function of the PTCSM theory arising from the
deformed conifold, computed via field theory localization by a method proposed
by Aganagic et al. We discuss possible origins of the mismatch
PkANN - II. A non-linear matter power spectrum interpolator developed using artificial neural networks
In this paper we introduce PkANN, a freely available software package for
interpolating the non-linear matter power spectrum, constructed using
Artificial Neural Networks (ANNs). Previously, using Halofit to calculate
matter power spectrum, we demonstrated that ANNs can make extremely quick and
accurate predictions of the power spectrum. Now, using a suite of 6380 N-body
simulations spanning 580 cosmologies, we train ANNs to predict the power
spectrum over the cosmological parameter space spanning confidence
level (CL) around the concordance cosmology. When presented with a set of
cosmological parameters ( and redshift ), the trained ANN interpolates the power
spectrum for at sub-per cent accuracy for modes up to
. PkANN is faster than computationally expensive
N-body simulations, yet provides a worst-case error per cent fit to the
non-linear matter power spectrum deduced through N-body simulations. The
overall precision of PkANN is set by the accuracy of our N-body simulations, at
5 per cent level for cosmological models with eV for all
redshifts . For models with eV, predictions are
expected to be at 5 (10) per cent level for redshifts (). The
PkANN interpolator may be freely downloaded from
http://zuserver2.star.ucl.ac.uk/~fba/PkANNComment: 21 pages, 14 figures, 2 table
Failures in Leadership : How and Why Wishy-Washy Politicians Equivocate on Japanese Political Interviews
Abstract
This paper examines how Japanese leading politicians deal with the communicative problems posed to them during broadcast political interviews. Based on data gathered during 14-month period in 2012–2013, the paper replicates and modifies the “Theory of Equivocation” to explore the extent to which national and local level politicians endeavor to affect the content of information distributed to the public and to influence the way people perceive events that take place in the public domain. Differentiating among selected groups of politicians, i.e., ruling and opposition parties’ members, Cabinet ministers and prime ministers, and local level politicians, the paper focuses on the ways Japanese politicians (and for comparison also nonpoliticians) equivocate during televised programs and the conditions underlying this equivocation, thereby also assesses the significance of these talk shows in the broader context of political communication in Japan.</jats:p
Culture or communicative conflict? : The analysis of equivocation in broadcast Japanese political interviews
The focus of this article is on equivocation in Japanese televised interviews, broadcast over a 14-month period in 2012-2013 (before and after the general election of December 16, 2012). An analysis was conducted of responses to questions by three different groups (national politicians, local politicians, and nonpoliticians). Results showed a striking level of equivocation by both national and local politicians, who together equivocated significantly more than nonpoliticians. Furthermore, national level Diet members equivocated significantly more than local politicians, and both coalition groupings when in power were significantly more likely to equivocate than when in opposition. The results were interpreted in terms of the situational theory of communicative conflict and also in terms of cultural norms characteristic of Japanese politics and society. The failure to consider the role of such norms, it is proposed, represents an important omission in the original theory of equivocation
PkANN - I. Non-linear matter power spectrum interpolation through artificial neural networks
We investigate the interpolation of power spectra of matter fluctuations
using Artificial Neural Network (PkANN). We present a new approach to confront
small-scale non-linearities in the power spectrum of matter fluctuations. This
ever-present and pernicious uncertainty is often the Achilles' heel in
cosmological studies and must be reduced if we are to see the advent of
precision cosmology in the late-time Universe. We show that an optimally
trained artificial neural network (ANN), when presented with a set of
cosmological parameters (Omega_m h^2, Omega_b h^2, n_s, w_0, sigma_8, m_nu and
redshift z), can provide a worst-case error <=1 per cent (for z<=2) fit to the
non-linear matter power spectrum deduced through N-body simulations, for modes
up to k<=0.7 h/Mpc. Our power spectrum interpolator is accurate over the entire
parameter space. This is a significant improvement over some of the current
matter power spectrum calculators. In this paper, we detail how an accurate
interpolation of the matter power spectrum is achievable with only a sparsely
sampled grid of cosmological parameters. Unlike large-scale N-body simulations
which are computationally expensive and/or infeasible, a well-trained ANN can
be an extremely quick and reliable tool in interpreting cosmological
observations and parameter estimation. This paper is the first in a series. In
this method paper, we generate the non-linear matter power spectra using
HaloFit and use them as mock observations to train the ANN. This work sets the
foundation for Paper II, where a suite of N-body simulations will be used to
compute the non-linear matter power spectra at sub-per cent accuracy, in the
quasi-non-linear regime 0.1 h/Mpc <= k <= 0.9 h/Mpc. A trained ANN based on
this N-body suite will be released for the scientific community.Comment: 12 pages, 9 figures, 2 tables, updated to match version accepted by
MNRA
Neutrino masses from clustering of red and blue galaxies: a test of astrophysical uncertainties
Combining measurements of the galaxy power spectrum and the cosmic microwave
background (CMB) is a powerful means of constraining the summed mass of
neutrino species sum(m_nu), but is subject to systematic uncertainties due to
non-linear structure formation, redshift-space distortions and galaxy bias. We
empirically test the robustness of neutrino mass results to these effects by
separately analyzing power spectra of red and blue galaxies from the Sloan
Digital Sky Survey (SDSS-II) Data Release 7 (DR7), combined with the CMB
five-year Wilkinson Microwave Anisotropy Probe (WMAP5) data. We consider
fitting for a range of maximum wavenumber k using twelve different galaxy bias
models. For example, using a new model based on perturbation theory and
including redshift space distortions (Saito et al. 2009), the all-galaxy power
spectrum combined with WMAP5 for a wavenumber range of k<0.2 Mpc/h yields 95%
CL sum(m_nu)<0.46 eV. The red and blue galaxy power spectra give 0.41 and 0.63
eV respectively for this model. Using mock catalogues, we find the expected
difference in these limits assuming a true neutrino mass of zero is 0.10 + or -
0.14 eV. Thus the difference of 0.22 eV between upper limits on neutrino mass
for red and blue galaxies is approximately 1 sigma from the expected value. We
find similar results for the other models and k ranges tested. This indicates
good agreement for current data but hints at possible issues for
next-generation surveys. Being able to perform such systematic tests is
advantageous, and future surveys would benefit by including broad galaxy
populations and luminosities that enable such a decomposition.Comment: 15 pages, 6 figures, matches version published in MNRA
Why did socialist economies fail? The role of factor inputs reconsidered
We re-estimate investment and present revised growth accounts for three socialist economies between 1950 and 1989. Government statistics reported distorted measures for both the rate and trajectory of productivity growth in Czechoslovakia, Hungary, and Poland. Researchers have benefited from revised output data, but continued to use official statistics on capital input, or estimated capital stock from official investment data. Investment levels and rates of capital accumulations were much lower than officially claimed and over-reporting worsened over time. A setback in factor accumulation, both equipment investment and labor input, contributed very significantly to the socialist growth failure of the 1980s
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