5,614 research outputs found
Working with the given
In this essay the author suggests that although the resulting architectural style may be ambiguous, a dialogue with an existing place can be creative, rewarding and appropriate
Sigurd Lewerentz: Church of St Peter, Klippan, 1963â66
This modest building questions basic assumptions about processes and finishes, about the nature of brickwork and the detailing of window frames â and provides a powerful space for worship
New meanings from old buildings
The three modest house projects described here are by three fellow travellers â the two authors and David Lea â interested in the Organic side of Modernism. Conversational partners who have worked together in various capacities over many years, they share a common conviction about âworking with the given
Collective labour supply with children
We extend the collective model of household behavior to allow for the
existence of public consumption. We show how this model allows to analyze
welfare consequences of policies aimed at changing the distribution of
power within the household. In particular, we claim that our setting provides
an adequate conceptual framework for addressing issues linked to the
âtargettingâ of specific benefits or taxes. We also show that the observation
of the labor supplies and the household demand for the public good allow
to identify individual welfare and the decision process. This requires either
a separability assumption, or the presence of a distribution factor
Competition and innovation: an inverted U relationship
This paper investigates the relationship between product market competition (PMC) and innovation. A Schumpeterian growth model is developed in which firms innovate âstep-by-stepâ, and where both technological leaders and their followers engage in R&D activities. In this model, competition may increase the incremental profit from innovating; on the other hand, competition may also reduce innovation incentives for laggards. This model generates four main predictions which we test empirically. First, the relationship between product market competition (PMC) and innovation is an inverted U-shape: the escape competition effect dominates for low initial levels of competition, whereas the Schumpeterian effect dominates at higher levels of competition. Second, the equilibrium degree of technological âneck-and-necknessâ among firms should decrease with PMC. Third, the higher the average degree of âneck-and-necknessâ in an industry, the steeper the inverted-U relationship between PMC and innovation in that industry. Fourth, firms may innovate more if subject to higher debt-pressure, especially at lower levels of PMC. We confront these four predictions with a new panel data set on UK firmsâ patenting activity at the US patenting office. The inverted U relationship, the neck and neck, and the debt pressure predictions are found to accord well with observed behavior in the data
Competition and innovation: an inverted U relationship?
This paper investigates the relationship between product market competition
and innovation. It uses the radical policy reforms in the UK as instruments
for changes in product market competition, and finds a robust inverted-U relationship
between competition and patenting. It then develops an endogenous
growth model with step-by-step innovation that can deliver this inverted-U pattern.
In this model, competition has an ambiguous effect on innovation. On the
one hand, it discourages laggard firms from innovating, as it reduces their rents
from catching up with the leaders in the same industry. On the other hand,
it encourages neck-and-neck firms to innovate in order to escape competition
with their rival. The inverted-U pattern results from the interplay between
these two effects, together with the effect of competition on the equilibrium
industry structure. The model generates two additional predictions: on the
relationship between competition and the average technological distance between
leaders and followers across industries; and on the relationship between
the distance of an industry to its technological frontier and the steepness of the
inverted-U. Both predictions are supported by the data
The effects of entry on incumbent innovation and productivity
How does firm entry affect innovation incentives and productivity growth in incumbent firms? Micro-data suggests that there is heterogeneity across industries--incumbents in technologically advanced industries react positively to foreign firm entry, but not in laggard industries. To explain this pattern, we introduce entry into a Schumpeterian growth model with multiple sectors which differ by their distance to the technological frontier. We show that technologically advanced entry threat spurs innovation incentives in sectors close to the technological frontier--successful innovation allows incumbents to prevent entry. In laggard sectors it discourages innovation--increased entry threat reduces incumbents' expected rents from innovating. We find that the empirical patterns hold using rich micro-level productivity growth and patent panel data for the UK, and controlling for the endogeneity of entry by exploiting the large number of policy reforms undertaken during the Thatcher era
Detection of a relic X-ray jet in Cygnus A
We present a 200 ks Chandra ACIS-I image of Cygnus A, and discuss a long
linear feature seen in its counterlobe. This feature has a non-thermal spectrum
and lies on the line connecting the brighter hotspot on the approaching side
and the nucleus. We therefore conclude that this feature is (or was) a jet.
However, the outer part of this X-ray jet does not trace the current counterjet
observed in radio. No X-ray counterpart is observed on the jet side. Using
light-travel time effects we conclude that this X-ray 50 kpc linear feature is
a relic jet that contains enough low-energy plasma (gamma ~ 10^3) to
inverse-Compton scatter cosmic microwave background photons, producing emission
in the X-rays.Comment: 4 pages. Proceedings of "High Energy Phenomena in Relativistic
Outflows", held in Dublin, Ireland, September 24-28, 200
On the origin of radio core emission in radio-quiet quasars
We present a model for the radio emission from radio-quiet quasar nuclei. We
show that a thermal origin for the high brightness temperature, flat spectrum
point sources (known as radio ``cores'') is possible provided the emitting
region is hot and optically-thin. We hence demonstrate that optically-thin
bremsstrahlung from a slow, dense disk wind can make a significant contribution
to the observed levels of radio core emission. This is a much more satisfactory
explanation, particularly for sources where there is no evidence of a jet, than
a sequence of self-absorbed synchrotron components which collectively conspire
to give a flat spectrum. Furthermore, such core phenomena are already observed
directly via milli-arcsecond radio imaging of the Galactic microquasar SS433
and the active galaxy NGC1068. We contend that radio-emitting disk winds must
be operating at some level in radio-loud quasars and radio galaxies as well
(although in these cases, observations of the radio cores are frequently
contaminated/dominated by synchrotron emission from jet knots). This
interpretation of radio core emission mandates mass accretion rates that are
substantially higher than Eddington. Moreover, acknowledgment of this mass-loss
mechanism as an AGN feedback process has important implications for the input
of energy and hot gas into the inter-galactic medium (IGM) since it is
considerably less directional than that from jets.Comment: to appear in ApJ Letters (4 pages
Wealth inequality in the United States and Great Britain
In this paper we describe the household wealth distribution in the US and UK, and compare both wealth inequality and the form in which wealth is held. Unconditionally, there are large differences in financial wealth between the two countries at the top fifth of the wealth distribution. And even after controlling for age and income differences between the two countries, we show that the median US household accumulates more financial wealth than their UK counterpart. We explore a number of alternative reasons for these differences and reject some explanations as implausible. These include differential receipt of financial inheritances or desired bequests, and differential average rates of return to corporate equity or housing. While less certain, we also argue that the differences that are concentrated among the older well-to-do are not likely due to differences in income or employment risks, savings for college expenses, or changes in permanent income. Some of the observed differences are due to what we refer to as "initial conditions", in particular previously high rates of corporate equity ownership in the US and housing ownership among young British households. But since these differences existed even in the early 1980s, initial conditions only provide a partial explanation. One further possibility may be that due to forced and voluntary annuitization of retirement incomes, older British households face considerably less longevity risk. Looking more widely, however, we find wealth held in different forms across the two countries, in particular in housing, which to some extent offsets the differences we observe in financial wealth patterns. We therefore point out that it is important that comparative studies compare genuine economic phenomena (such as the ability to smooth consumption) rather than particular economic measurements (such as the level of wealth in any one particular form). We also argue that it is crucial that comparative exercises of this form acknowledge the importance of institutional differences across countries, and in this particular comparison the role of housing markets, annuity markets and stock markets appear crucial and all merit further more detailed research. On balance, we are encouraged by the degree to which a detailed investigation can point to potential explanations of observed wealth differences between the two countries, and such an investigation will also lead to a deeper understanding of the household wealth accumulation process more generally.
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