Did Galaxy Assembly and Supermassive Black-Hole Growth go hand-in-hand?

In this paper, we address whether the growth of supermassive black-holes has kept pace with the process of galaxy assembly. For this purpose, we first searched the Hubble Ultra Deep Field (HUDF) for "tadpole galaxies", which have a knot at one end and an extended tail. They appear dynamically unrelaxed -- presumably early-stage mergers -- and make up ~6% of the field galaxy population. Their redshift distribution follows that of field galaxies, indicating that -- if tadpole galaxies are indeed dynamically young -- the process of galaxy assembly generally kept up with the reservoir of field galaxies as a function of epoch. Next, we present a search for HUDF objects with point-source components that are optically variable (at the >~3.0 sigma level) on timescales of weeks--months. Among 4644 objects to i_AB=28.0 mag (10 sigma), 45 have variable point-like components, which are likely weak AGN. About 1% of all field objects show variability for 0.1 < z < 4.5, and their redshift distribution is similar to that of field galaxies. Hence supermassive black-hole growth in weak AGN likely also kept up with the process of galaxy assembly. However, the faint AGN sample has almost no overlap with the tadpole sample, which was predicted by recent hydrodynamical numerical simulations. This suggests that tadpole galaxies are early-stage mergers, which likely preceded the ``turn-on'' of the AGN component and the onset of visible point-source variability by >~1 Gyr.Comment: 9 pages, Latex2e requires 'elsart' and 'elsart3' (included), 10 postscript figures. To appear in the Proceedings of the Leiden Workshop on "QSO Host Galaxies: Evolution and Environment", eds. P.D. Barthel & D.B. Sanders (New Astron. Rev., 2006

Growth in a cross-section of cities: location, increasing returns or random growth?

This article analyzes empirically the main existing theories on income and population city growth: increasing returns to scale, locational fundamentals and random growth. To do this we implement a threshold nonlinearity test that extends standard linear growth regression models to a dataset on urban, climatological and macroeconomic variables on 1,175 U.S. cities. Our analysis reveals the existence of increasing returns when per-capita income levels are beyond $19; 264. Despite this, income growth is mostly explained by social and locational fundamentals. Population growth also exhibits two distinct equilibria determined by a threshold value of 116,300 inhabitants beyond which city population grows at a higher rate. Income and population growth do not go hand in hand, implying an optimal level of population beyond which income growth stagnates or deteriorates.Threshold nonlinearity test, locational fundamentals, multiple equilibria, random growth

Unemployment and endogenous growth

In this paper we develop a two-sector endogenous growth model with a dual labour market, based on efficiency wages. Growth is driven by intentional R&D performed in the high-tech and high-wage sector. It is examined how a change in rivalry among firms affects simultaneously growth and unemployment. On the one hand, an increase of the elasticity of substitution between the product varieties of different high-tech firms reduces market power and leads to higher growth but reduces job prospects. On the other hand, if barriers to entry exist, an increase of the number of rivals in the market (due to removal of entry barriers) leads to lower growth, whereas the effect on aggregate employment is ambiguous.Economic Growth;Wages;Unemployment;Labour Market;Growth Models;labour economics

Energy and Smart Growth: It's about How and Where We Build

By efficiently locating development, smarter growth land use policies and practices offer a viable way to reduce U.S. energy consumption. Moreover, by increasing attention on how we build, in addition to where we build, smart growth could become even more energy smart. The smart growth and energy efficiency movements thus are intrinsically linked, yet these two fields have mostly operated in separate worlds. Through greater use of energy efficient design, and renewable energy resources, the smart growth movement could better achieve its goals of environmental protection, economic security and prosperity, and community livability. In short, green building and smart growth should go hand in hand. Heightened concern about foreign oil dependence, climate change, and other ill effects of fossil fuel usage makes the energy-smart growth collaboration especially important. Strengthening this collaboration will involve overcoming some hurdles, however, and funders can play an important role in assisting these movements to gain strength from each other. This paper contends there is much to be gained by expanding the smart growth movement to include greater attention on energy. It provides a brief background on current energy trends and programs, relevant to smart growth. It then presents a framework for understanding the connections between energy and land use which focuses on two primary issues: how to build, which involves neighborhood and building design, and where to build, meaning that location matters. The final section offers suggestions to funders interesting in helping accelerate the merger of these fields

Two properties of volume growth entropy in Hilbert geometry

The aim of this paper is to provide two examples in Hilbert geometry which show that volume growth entropy is not always a limit on the one hand, and that it may vanish for a non-polygonal domain in the plane on the other hand

DEBT, FINANCIAL FRAGILITY AND ECONOMIC GROWTH: A POST-KEYNESIAN MACROMODEL

It is developed a mathematical post-keynesian macromodel of capacity utilization and growth in which the supply of credit-money is endogenous and firms' debt position - and thus the financial fragility of the economy - is explicitly modeled. Both the influence of interest rate and indebtedness on capacity utilization and the rates of profit and growth, on the one hand, and the effect of the parameters of the saving and investment functions on financial fragility, on the other hand, are carefully analyzed.

Competition and growth: reconciling theory and evidence

From book description: Though competition occupies a prominent place in the history of economic thought, among economists today there is still a limited, and sometimes contradictory, understanding of its impact. In Competition and Growth, Philippe Aghion and Rachel Griffith offer the first serious attempt to provide a unified and coherent account of the effect competition policy and deregulated entry has on economic growth. The book takes the form of a dialogue between an applied theorist calling on "Schumpeterian growth" models and a microeconometrician employing new techniques to gauge competition and entry. In each chapter, theoretical models are systematically confronted with empirical data, which either invalidates the models or suggests changes in the modeling strategy. Aghion and Griffith note a fundamental divorce between theorists and empiricists who previously worked on these questions. On one hand, existing models in industrial organization or new growth economics all predict a negative effect of competition on innovation and growth: namely, that competition is bad for growth because it reduces the monopoly rents that reward successful innovators. On the other hand, common wisdom and recent empirical studies point to a positive effect of competition on productivity growth. To reconcile theory and evidence, the authors distinguish between pre- and post-innovation rents, and propose that innovation may be a way to escape competition, an idea that they confront with microeconomic data. The book's detailed analysis should aid scholars and policy makers in understanding how the benefits of tougher competition can be achieved while at the same time mitigating the negative effects competition and imitation may have on some sectors or industries

Growth and Poverty in Pakistan: Implications for Governance

According to the Economic Surveys, Pakistan’s real GDP has grown at an average annual rate of 6.8 percent in the 1960s, 4.8 percent in the 1970s, 6.5 percent in the 1980s and 4.7 percent in the 1990s. However, that did not seem to have mitigated poverty as parallel to this growth the number of poor also kept swelling. Although different estimates put number of poor in Pakistan around 50 million, the actual could be more [Ahmad (2001)]. The average growth rates in the first halfcentury of Pakistan have been around 2 percent [Hasan (1997)]. It is pertinent to state that this discussion paper is not an attempt to challenge the figures either of the growth rates or the numbers of the poor in Pakistan. This is rather an attempt to understand the correlation of governance with growth on one hand and poverty on the other. It offers conceptual analysis of the concepts and their respective interpretation, explanation, application and ensuing misunderstandings. This paper has also attempted to challenge certain (usual) assumptions and perceptions regarding the role and relationship of growth and governance in reducing poverty in Pakistan. One has pointed out that most of the studies on the subject focus on symptoms and not the causes of poverty. This leads to on one hand growth of poverty, as poverty does not seem to halt despite certain evidence of relatively high growth particularly in 1960s. On the other hand we witness poverty of growth as whatever growth we have had it has hitherto failed either translating into corresponding mitigation of poverty or equitable collective prosperity. This is because there have not been efforts at governance level to ensure equity of impact of growth through adequate distribution mechanisms, sufficient social and human investments leading to education and skill development of women and men, who in turn could benefit from opportunities arising by way of process of economic growth.

Are Cardiovascular Diseases Bad for Economic Growth?

We assess the impact of cardiovascular disease (CVD) mortality on economic growth, using a dynamic panel growth regression framework taking into account potential endogeneity problems. We start from a worldwide sample of countries for which data was available and detect a non-linearity in the influence of working age CVD mortality rates on growth across the per capita income scale. We then split the sample (according to the resulting income threshold) into low- and middle-income countries on one hand, and high-income countries on the other hand. In the latter sample we find a robust negative contribution of increasing CVD mortality rates on subsequent five-year growth rates. Not too surprisingly, we find no significant impact in the low- and middle-income country sample.cardiovascular disease, growth empirics, dynamic panel data estimator