The role of lead firms in cluster evolution: The case of the Manchester television cluster

ABSTRACT

The author utilizes recent work in evolutionary economic geography to examine the television cluster in Manchester, UK. A path dependency approach is used to trace the evolutionary phases of the cluster, and to reveal the shifting dynamics of the cluster and the role of key actors. The article focuses on the role of two lead firms – the BBC and Granada. Based on qualitative interview and participant observation data, supplemented with contextual quantitative data collection, the study presents the results of longitudinal research conducted between 2000 and 2014. The author finds that the role of lead firms varied according to the evolutionary phase of the cluster. The role of the broadcasters was most significant during the emergence and growth of the cluster. Both the lead firm and the cluster have been impacted by exogenous factors, particularly regulatory changes. A key trigger point in 2003 led to the evolutionary trajectory of the cluster shifting into decline and stagnation.     

Product water mass formation by turbulent density currents from a high-order nonhydrostatic spectral element model

In light of the pressing need for development of parameterizations of gravity current entrainment in ocean general circulation models, the behavior of turbulent gravity currents in the presence of ambient stratification is studied via numerical simulation, for cases in which equilibrated product water masses are formed. The main objective is to explore how the ambient stratification impacts entrainment and the properties of product water masses, which are of ultimate interest to ocean and climate modelers. Numerical experiments are conducted by employing the high-order nonhydrostatic spectral element model Nek5000. It is investigated how the separation level of the current from the bottom, the propagation speed, the salinity of the product water masses, and the transport and entrainment of the gravity current are affected as a function of the strength of the ambient stratification and the slope angle. Results show that, for the case of constant slope angle and linear ambient stratification, the gravity current separates from the bottom such that the entrained mass flux is independent of the slope angle. The entrainment mass transport, product mass transport, and product salinity then depend only on the ambient stratification, and these quantities are approximated as simple algebraic functions of the ambient stratification parameter that modify the source properties.     

Quantitative estimation of illite-smectite mixed phases formed during burial diagenesis

Summary With reference to the previously published papers byReynolds andHower (1970) andPerry andHower (1970) pelitic sediments from bore hole samples from the Tertiary sequence of the Vienna Basin have been studied to investigate the layer silicate assemblages and to carry out a quantitative estimation of the mixed-layering in the illitesmectite mixtures. Beside these problems one of the primary purposes of this paper is to indicate how interfering reflections from detrital layer silicates can be handled and resolved from diffraction patterns. The samples correspond to clayey silts. Within the less than 0.2 micron fractions they essentially contain mica, kaolinite and illite-smectite as expandable phase. Dependent on depth the composition of these mixtures is intermediate between an interstratified mixed layer phase consisting of about 75 percent smectite layers and 25 percent illite and an ordered mixture which contains about 20 percent smectite and 80 percent illite layers.Since the mineral components maintain essentially constant portions throughout the samples, mica and kaolinite do not enter the illitization reaction. The necessary potassium and aluminum ions were derived from the nonclay constituents.

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Quantitative Abschätzung versenkungsdiagenetisch gebildeter Illit-Smektit Mischphasen

Zusammenfassung In Anlehnung an die vonReynolds undHower (1970) sowie vonPerry undHower (1970) aufgezeigten Untersuchungsmethoden wurden an Beispielen von bohrproben tertiärer Feinkornsedimente aus dem Wiener Becken Untersuchungen zur Identifizierung und quantitativen Erfassung von Illit-Smektit Mixed-Layer-Phasen durchgeführt, wobei die Behandlung bzw. Ausschaltung von Störeffekten durch detritäre Mineralanteile im Rahmen dieser Methoden in den Vordergrund der Arbeit gestellt wird. Die durchwegs tonigen Silten entsprechenden Proben enthalten in der Fraktion kleiner 0,2 Mikron im wesentlichen Glimmer, Kaolinit und als quellfähige Phase Illit-Smektit, die mit zunehmender Teufevon einer Mischphase mit zufälliger Ordnung und 75% Smektit-bzw. 25% Illitanteilen zu einer geordneten Mixed-Layer-Bildung von 20% Smektit und 80% Illit überleitet.Da die Zusammensetzung der Proben hinsichtlich der Verbreitung von Illit-Smektit, Glimmer und Kaolinit keine Veränderungen aufweist, können Beeinflussungen der beiden zuletzt genannten Phasen im Zuge des Illitisierungsprozesses ausgeschlossen werden. Die zur Illitbildung erforderliche Zufuhr von Kalium und Aluminium erfolgte demnach auf Kosten der Nicht-Ton-Minerale.

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With 4 Figures     

Relation between n-alkane distributions and effective coalification temperatures in some Permian shales

In Permian shales of the Sydney Basin, Australia, n-alkane distributions have been compared with effective coalification temperatures (ECTs) estimated from vitrinite reflectivities. The upper, non-marine part of the section shows evidence of progressive cracking (shift of n-alkane maximum toward shorter chains and tendency to eliminate longer chains) as depth and ECT increase; but this trend is not maintained in the underlying marine section.All samples show lack of a maximum in the longer-chain n-alkane distribution. Possible reasons discussed are (i) a cracking rate of long chains greater than their formation rate; (ii) a need for higher temperatures than the rock has so far undergone to produce a new crop of long chains; or (iii) exhaustion of the straight-chain generating potential of the kerogen. Pyrolysis experiments may be effective in testing these possibilities.The linking of ECTs to alteration stages of sediment hydrocarbons opens the possibility of comparing these stages among formations which differ in age and organic and inorganic composition, and among basins of diverse geological history.     

A note on the boundary layer at the floor of a tidal channel

A numerical model is used to study the effect of non-linearities on the dynamics of the boundary layer at the floor of a tidal channel. A feature of the model is the use of a non-linear transfer term to represent the effect of the turbulent stress in the system. Numerical evaluations are made in order to determine whether this term leads to distortions in the current profiles that are comparable with those normally associated with the inertia terms. Comparisons are also made between the predicted current profiles and those obtained from a simple Stokes' “shear-wave” solution.     

The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments

Results are presented from a new version of the Hadley Centre coupled model (HadCM3) that does not require flux adjustments to prevent large climate drifts in the simulation. The model has both an improved atmosphere and ocean component. In particular, the ocean has a 1.25° × 1.25° degree horizontal resolution and leads to a considerably improved simulation of ocean heat transports compared to earlier versions with a coarser resolution ocean component. The model does not have any spin up procedure prior to coupling and the simulation has been run for over 400 years starting from observed initial conditions. The sea surface temperature (SST) and sea ice simulation are shown to be stable and realistic. The trend in global mean SST is less than 0.009 °C per century. In part, the improved simulation is a consequence of a greater compatibility of the atmosphere and ocean model heat budgets. The atmospheric model surface heat and momentum budget are evaluated by comparing with climatological ship-based estimates. Similarly the ocean model simulation of poleward heat transports is compared with direct ship-based observations for a number of sections across the globe. Despite the limitations of the observed datasets, it is shown that the coupled model is able to reproduce many aspects of the observed heat budget. Received: 1 October 1998 / Accepted: 20 July 1999     

Mean meridional currents in the central and eastern equatorial Atlantic

Ship-based acoustic Doppler current profiler (ADCP) velocity measurements collected by several major field programs in the tropical Atlantic are averaged and combined with estimates of the mean near-surface velocity derived from drifters and Argo float surface drifts (ADCP+D) to describe the mean cross-equatorial and vertical structure of the meridional currents along 23°W and 10°W. Data from moored ADCPs and fixed-depth current meters, a satellite-derived velocity product, and a global ocean reanalysis were additionally used to evaluate the mean ADCP+D meridional velocity. The dominant circulation features in the long-term mean ADCP+D meridional velocity in the upper 100 m are the tropical cells (TCs) located approximately between 5°S and 5°N, with near-surface poleward flow and subsurface equatorward flow that is stronger and shallower in the northern cell compared to the southern cell. The thickness of the surface limb of the TCs decreases and the northern cell is found to shift further south of the equator from the central to eastern tropical Atlantic. Analysis of two-season means estimated from the ship-based ADCP, near-surface drift, and moored velocity data, as well as the simulated fields, indicates that the maximum poleward velocity in the surface limb of the TCs intensifies during December–May along 23°W largely due to seasonal compensation between the geostrophic and ageostrophic (or wind-driven) components of the meridional velocity, whereas the maximum equatorward flow in the subsurface limb of the northern cell intensifies during June–November along both 23°W and 10°W due to the seasonality of the geostrophic meridional velocity.     

Polycyclic aromatic hydrocarbons in Australian coals. I. Angularly fused pentacyclic tri- and tetraaromatic components of Victorian brown coal

Analysis of the tri- and tetraaromatic hydrocarbon fractions of a brown coal sample from the Latrobe Valley, Victoria, Australia indicate the predominance of pentacyclic hydroaromatic components. Many of these have not been previously reported in the literature, but are obviously diagenetically related to triterpenoids naturally occurring in the biosphere. The components whose molecular structures have been confirmed, together with those for which tentative structural assignments are given, offer strong support for a theory of progressive diagenetic aromatization of C-3 oxygenated triterpenoids, commencing from ring A. Other compounds present in smaller amounts suggest that 1,2-methyl shift reactions also occur prior to or during aromatization. There is a notable absence of polycyclic aromatic hydrocarbons (PAH's) which can be diagenetically related to the steroid or extended-side-chain hopane skeletons.