Sing a New Song to the City: Ambient Rhetoric and Urban Hymns

Hymns are a key component of how Christians express their faith. But many of these hymns do represent the rhythms and sensibilities of an older and largely agrarian world. Using the concept of “ambient rhetoric,” Adam Copeland suggests that it is time for other hymns that represent the ethos of daily life in an increasingly urbanized world, hymns that will speak to the realities of urban culture

The Ten Commandments 2.0

Since the Ten Commandments still enjoy a primary place in both church teaching and cultural debate, it will be both helpful and faithful to interpret them anew in the light of our new media and new technologies. Adam Copeland does just that in this article

The Response of Prices, Sales, and Output to Temporary Changes in Demand

We determine empirically how the Big Three automakers accommodate shocks to demand. They have the capability to change prices, alter labor inputs through temporary layoffs and overtime, or adjust inventories. These adjustments are interrelated, non-convex, and dynamic in nature. Combining weekly plant-level data on production schedules and output with monthly data on sales and transaction prices, we estimate a dynamic profit-maximization model of the firm. Using impulse response functions, we demonstrate that when an automaker is hit with a demand shock sales respond immediately, prices respond gradually, and production responds only after a delay. The size of the immediate sales response is linear in the size of the shock, but the delayed production response is non-convex in the size of the shock. For sufficiently large shocks the cumulative production response over the product cycle is an order of magnitude larger than the cumulative price response. We examine two recent demand shocks: the Ford Explorer/Firestone tire recall of 2000, and the September 11, 2001 terrorist attacks

CMB constraints on cosmic strings and superstrings

We present the first complete MCMC analysis of cosmological models with evolving cosmic (super)string networks, using the Unconnected Segment Model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constraints on ΛCDM and string network parameters, namely the string tension Gμ, the loop-chopping efficiency cr and the string wiggliness α. For cosmic superstrings, we obtain joint constraints on the fundamental string tension GμF, the string coupling gs, the self-interaction coefficient cs, and the volume of compact extra dimensions w. This constitutes the most comprehensive CMB analysis of ΛCDM cosmology + strings to date. For ordinary cosmic string networks our updated constraint on the string tension, obtained using Planck2015 temperature and polarisation data, is Gμ < 1.1 × 10^(−7) in relativistic units, while for cosmic superstrings our constraint on the fundamental string tension after marginalising over gs, cs and w is GμF < 2.8 × 10^(−8)

Constraints on primordial gravitational waves from the cosmic microwave background

Searches for primordial gravitational waves have resulted in constraints in a large frequency range from a variety of sources. The standard Cosmic Microwave Background (CMB) technique is to parameterise the tensor power spectrum in terms of the tensor-to-scalar ratio, r, and spectral index, nt, and constrain these using measurements of the temperature and polarization power spectra. Another method, applicable to modes well inside the cosmological horizon at recombination, uses the shortwave approximation, under which gravitational waves behave as an effective neutrino species. In this paper we give model-independent CMB constraints on the energy density of gravitational waves, Ωgw h2, for the entire range of observable frequencies. On large scales, f 10−16 Hz, we reconstruct the initial tensor power spectrum in logarithmic frequency bins, finding maximal sensitivity for scales close to the horizon size at recombination. On small scales, f 10−15 Hz, we use the shortwave approximation, finding Ωgw h2 < 1.7 ×10−6 for adiabatic initial conditions and Ωgw h2 < 2.9 ×10−7 for homogeneous initial conditions (both 2σ upper limits). For scales close to the horizon size at recombination, we use second-order perturbation theory to calculate the back-reaction from gravitational waves, finding Ωgw h2 < 8.4 ×10−7, in the absence of neutrino anisotropic stress and Ωgw h2 < 8.6 ×10−7 when including neutrino anisotropic stress. These constraints are valid for 10−15 Hz f 3 × 10−16 Hz

Constraints on the fundamental string coupling from B-mode experiments

We study signatures of cosmic superstring networks containing strings of multiple tensions and Y-junctions, on the cosmic microwave background (CMB) temperature and polarisation spectra. Focusing on the crucial role of the string coupling constant $g_s$, we show that the number density and energy density of the scaling network are dominated by different types of string in the $g_s \sim 1$ and $g_s \ll 1$ limits. This can lead to an observable shift in the position of the B-mode peak --- a distinct signal leading to a direct constraint on $g_s$. We forecast the joint bounds on $g_s$ and the fundamental string tension $\mu_F$ from upcoming and future CMB polarisation experiments, as well as the signal to noise in detecting the difference between B-mode signals in the limiting cases of large and small $g_s$. We show that such a detectable shift is within reach of planned experiments.Comment: 4 pages, 4 figures; v2: matches version published in PR

CMB constraints on monodromy inflation at strong coupling

We carry out a thorough numerical examination of field theory monodromy inflation at strong coupling. We perform an MCMC analysis using a Gaussian likelihood, fitting multiparameter models using CMB constraints on the spectral index and the tensor to scalar ratio. We show that models with uniquely positive Wilson coefficients are ruled out. If there are coefficients that can take on both signs, there can be a cancellation of terms that flattens the potentials and allows one to satisfy current data, and forecasts with strong constraints on the tensor to scalar ratio. Models of field theory monodromy are naturally enhanced to include a mechanism for canceling off radiative corrections to vacuum energy, via vacuum energy sequestering (VES). Although they include a much larger parameter space, we find that a similar numerical examination yields no significant change in the Bayesian evidence for VES enhanced models, with naturalness considerations making them more attractive from a theoretical perspective