Cluster Dynamics: New Evidence and Projections for Computing Services in Great Britain*

Abstract. This paper tests some of the main hypotheses about the importance of horizontal clusters for the growth of employment in small firms using data from Computing Services in Great Britain. In the main section of the paper, spatial econometric models are estimated controlling for supply‐ and demand‐side conditions to isolate the effect of initial cluster intensity. The paper then projects cluster development using the fitted model, showing how clusters are likely to emerge and intensify. One aspect of the paper is the existence of a de‐clustering mechanism due to congestion effects.     

Fluidized sandstone intrusions as an indicator of Paleostress orientation, Santa Cruz, California

The late Miocene sandstone intrusions of northern Santa Cruz County, California, are the largest subaerial exposures of clastic intrusions on earth. The intrusions are sourced from a sandstone, underlying mudstone, accumulated in an outer shelf to upper slope environment. Dikes are the most frequent intrusion type, reach the greatest thickness and tend to strike north‐east and dip steeply. One giant dike is more than 150 m wide. Sills are least frequent, locally > 8 m thick and have no clear preferred geographical distribution. Clustered intrusions are commonly < 10 cm thick and mostly composed of dikes of various attitudes. The majority of the intrusions probably were injected shallowly as some extrude onto the seafloor. The local seafloor extrusion also indicates injection during the deposition of the Santa Cruz Mudstone (7–9 Ma). The intrusions are concentrated at the basin margin. Fluid pressure at the centre of the basin and perhaps hydrocarbons were communicated to the basin margin through the then sand, causing fluid overpressures that contributed to the fluidization and intrusion into the overlying mudstone. Primarily north‐east‐striking, steeply dipping dikes and secondarily, shallowly dipping sills are most significant in terms of regional connectivity of intrusions and physical dilation of the formation. The orientation of the dikes and sills indicates a regional stress field with a horizontal NE–SW maximum and a NW–SE minimum compressive direction. The simultaneous development of dikes and sills suggests similar magnitudes of the minimum and intermediate principal stresses. Preferential weakness along bedding contributed to the development of sills. Palaeomagnetic data indicate no significant block rotation around a vertical axis. The maximum principal stress direction indicated by the intrusions is about 55° to the San Gregorio Fault and about 70° to the San Andreas Fault during the late Miocene. This stress field is similar to the modern stress field and suggests moderate fault weakness.     

Ancient hydrocarbon seeps from the Mesozoic convergent margin of California: carbonate geochemistry, fluids and palaeoenvironments

More than a dozen hydrocarbon seep‐carbonate occurrences in late Jurassic to late Cretaceous forearc and accretionary prism strata, western California, accumulated in turbidite/fault‐hosted or serpentine diapir‐related settings. Three sites, Paskenta, Cold Fork of Cottonwood Creek and Wilbur Springs, were analyzed for their petrographic, geochemical and palaeoecological attributes, and each showed a three‐stage development that recorded the evolution of fluids through reducing–oxidizing–reducing conditions. The first stage constituted diffusive, reduced fluid seepage (CH₄, H₂S) through seafloor sediments, as indicated by Fe‐rich detrital micrite, corroded surfaces encrusted with framboidal pyrite, anhedral yellow calcite and negative cement stable isotopic signatures (δ¹³C as low as ?35.5‰ PDB; δ¹⁸O as low as ?10.8‰ PDB). Mega‐invertebrates, adapted to reduced conditions and/or bacterial chemosymbiosis, colonized the sites during this earliest period of fluid seepage. A second, early stage of centralized venting at the seafloor followed, which was coincident with hydrocarbon migration, as evidenced by nonluminescent fibrous cements with δ¹³C values as low as ?43.7‰ PDB, elevated δ¹⁸O (up to +2.3‰ PDB), petroleum inclusions, marine borings and lack of pyrite. Throughout these early phases of hydrocarbon seepage, microbial sediments were preserved as layered and clotted, nondetrital micrites. A final late‐stage of development marked a return to reducing conditions during burial diagenesis, as implied by pore‐associated Mn‐rich cement phases with bright cathodoluminescent patterns, and negative δ¹⁸O signatures (as low as ?14‰ PDB). These recurring patterns among sites highlight similarities in the hydrogeological evolution of the Mesozoic convergent margin of California, which influenced local geochemical conditions and organism responses. A comparison of stable carbon and oxygen isotopic data for 33 globally distributed seep‐carbonates, ranging in age from Devonian to Recent, delineated three groupings that reflect variable fluid input, different tectono‐sedimentary regimes and time–temperature‐dependent burial diagenesis.     

Book reviews

CHINA AND THE OVERSEAS CHINESE. A STUDY OF PEKING'S CHANGING POLICY, 1949–1970. Stephen FitzGerald. Cambridge University Press, 1972. 268 pp. £5.90.

CHINA'S WORLD: THE FOREIGN POLICY OF A DEVELOPING STATE. J. D. Simmonds. Australian National University Press, 1970. 0–7081–0694–3. 200 pp. $6.95.

THE CONVENTIONS OF CRISIS: A STUDY IN DIPLOMATIC MANAGEMENT. Coral Bell. Oxford University Press for the Royal Institute of International Affairs, 1971. 0–19–285054–7. 131 pp. $3.40 paper.

FROM CRISIS TO CRISIS: PAKISTAN 1962–1969. Herbert Feldmon. Oxford University Press, London, 1972. 0–19–215192–4. 340 pp. $17.10.

INDIAN REVOLUTIONARIES ABROAD. A. C. Bose. Bha Rati Bhawan, Patna, 1971. 268 pp. Rs. 30.00.

THE AUSTRALIAN‐NEW ZEALAND AGREEMENT 1944. Robin Kay (ed.). A. R. Shearer, Government Printer, Wellington, New Zealand, 1972. 297 pp. $NZ7.50.

PASSING FOR WHITE. A STUDY OF RACIAL ASSIMILATION IN A SOUTH AFRICAN SCHOOL. Graham Watson. Tavistock, London, 1970. 422–75470–6. 130 pp. $2.70, Social Science paperback, $7.10 hard‐cover.

ABORIGINES AND SETTLERS: THE AUSTRALIAN EXPERIENCE (1788–1939). Henry Reynolds. Cassell, Melbourne, 1972. 422–75470–6. $3.75.

WORLD ARMAMENTS AND DISARMAMENT: SIPRI YEARBOOK 1972. Almqvist and Wiksell, for SIPRI (Stockhohn International Peace Research Institute), Stockholm 1972. 91–85114–12‐X. 611 pp. $US15.00.

THE PROBLEM OF CHEMICAL AND BIOLOGICAL WARFARE. Volume V: THE PREVENTION OF CBW. SIPRI (Stockholm International Peace Research Institute). Almqvist & Wiksell, Stockholm and Humanities Press, New York, 1971. 287 pp. $13 hard cover.

IN THE MINDS OF MEN: UNESCO 1946–1971. Gian Franco Pompei and others. UNESCO, Paris, 1972. 319 pp. $3.35 paper.

PROBLEMS OF INTERNATIONAL AIR TRANSPORT POLICY. Paul Heller. New Zealand Institute of International Affairs, 1972. 50 pp.

BRAZIL: THE PEOPLE AND THE POWER. M. Arraes. Pelican Latin American Library. $1.35.     

The Identity of Capitalists and the Legitimacy of Capitalism: Sri Lanka since Independence

In many Asian countries, the early decades of independence after World War II were marked by tension between ‘indigenous’ political elites and business elites that were in large part alien, or from minority ethnic groups. This tension was one reason for the preference that most governments showed for statist and nationalist economic policies. It has abated in most cases; political and business elites now tend to pursue more co-operative strategies. Much of the explanation for this lies in changes in the international political economy that made market-oriented economic policies more attractive to political elites. There are in addition internal political reasons for this rapprochement. These vary from case to case, and have been explored in most detail by scholars in relation to the Southeast Asian countries where Overseas Chinese have dominated larger scale business. This article extends this literature by examining the causes of the gradual rapprochement between ‘majority’ politics and ‘minority’ business in Sri Lanka.     

Participant observation in obesity research with children: striated and smooth spaces

This article discusses the value of conducting participant observation in obesity research with children in an Australian community setting. Obesity is highly stigmatized, and the use of activity-based interviews exposed the intellectual and embodied consciousness that children negotiate when they take part in research about food and bodies. Instead of opening up possibilities, interview-based activities can lead to a moral correctness about healthy lifestyles. It was through participant observation, in engagement with what Deleuze and Guattari [1988 Deleuze, G., and F. Guattari. 1988. A Thousand Plateaus: Capitalism and Schizophrenia. London: Athlone Press. [Google Scholar]. A Thousand Plateaus: Capitalism and Schizophrenia. London: Athlone Press] call striated and smooth (or regulated and unregulated) spaces of children's everyday activities, that richer understandings of obesity and children's bodies became apparent. We argue that without participant observation, our understandings of what children say and draw about healthy lifestyles may be limited by the striated spaces in which we conduct our research and the constraints that accompany the cultural politics of childhood and obesity.