AGGLOMERATION VERSUS PRODUCT VARIETY: IMPLICATIONS FOR REGIONAL INEQUALITIES*

ABSTRACT We investigate how cross‐country differences in firms' fixed set‐up costs affect the trade‐off between global efficiency and spatial equity. Our analysis reveals that the standard assumption of symmetry in set‐up costs masks the existence of an interesting effect: the range of available varieties depends on the spatial distribution of firms. In such a setting, where the market outcome leads to excessive agglomeration in the symmetric case, a planner may opt for asymmetric set‐up costs and even more agglomeration. We show that the planner will always favor lower set‐up costs in the large country with more agglomeration when the consumer's marginal preference for variety is high, or with less agglomeration when the consumer's marginal preference for variety is low.     

Idealistisch geprägte Axiomatik des Selbstorganisationsparadigmas

The essay shows that the axiomatics of the systemic‐cybernetic‐biological theory of self‐organization by Humberto Maturana and Francisco Varela have their roots in the philosophy of German Idealism. Especially the completely subject‐centered philosophy of Johann Gottlieb Fichte already contains the central axiomatics of Maturana and Varela.     

Fracture sealing and fluid overpressures in limestones of the Jabal Akhdar dome,Oman mountains

Fractures are important conduits for fluid flow in the Earth's crust. To better understand the spatial and temporal relations among fracturing, fracture sealing, and fluid flow, we have studied fractures, faults, and veins in a large dome (Jabal Akhdar) in the Oman mountains. Our work combines the results of meso‐ and microstructural analyses and stable isotope analyses. Seven generations of fractures and veins have been identified in the carbonate‐dominated dome. The earliest generations of veins developed during extension and subsidence of the Mesozoic basin. These veins formed in the inclined segments of bedding‐parallel stylolites and in extensional fractures that are perpendicular to bedding (#1 and #2, respectively). These extension‐related veins are truncated by bedding‐parallel veins (#4) that formed during top‐to‐north bedding‐parallel shear of both the northern and southern limbs of the dome. These veins are consistent with a change in stress regime and may be related to an earlier generation of strongly deformed pinch‐and‐swell veins (#3) that are exposed locally on the southern limb of the dome. Normal faults contain a set of en‐echelon tension gashes (#5) and veins emplaced in dilational jogs along the fault planes (#6). In the northern part of the dome, veins (#7) associated with thrusts post‐date the normal faults. Samples of veins and their host rocks were analyzed to provide information on fluid‐rock interaction in the dome and the scale(s) of fluid movement. Oxygen isotope values range from +16.2 to +29.3‰; carbon isotope values range from 0 to +3.6‰. The results of the structural and isotopic analyses are consistent with the early veins (#2–#5) having precipitated from overpressured fluid in a isotopically rock‐buffered system. During normal faulting (#5 and #6), a more open system allowed external fluid to infiltrate the dome at drained conditions and precipitate the youngest sets of veins (#6 and #7).     

Precipitation of lead–zinc ores in the Mississippi Valley‐type deposit at Trèves,Cévennes region of southern France

The Trèves zinc–lead deposit is one of several Mississippi Valley‐type (MVT) deposits in the Cévennes region of southern France. Fluid inclusion studies show that the ore was deposited at temperatures between approximately 80 and 150°C from a brine that derived its salinity mainly from the evaporation of seawater past halite saturation. Lead isotope studies suggest that the metals were extracted from local basement rocks. Sulfur isotope data and studies of organic matter indicate that the reduced sulfur in the ores was derived from the reduction of Mesozoic marine sulfate by thermochemical sulfate reduction or bacterially mediated processes at a different time or place from ore deposition. The large range of δ³⁴S values determined for the minerals in the deposit (12.2–19.2‰ for barite, 3.8–13.8‰ for sphalerite and galena, and 8.7 to ?21.2‰ for pyrite), are best explained by the mixing of fluids containing different sources of sulfur. Geochemical reaction path calculations, based on quantitative fluid inclusion data and constrained by field observations, were used to evaluate possible precipitation mechanisms. The most important precipitation mechanism was probably the mixing of fluids containing different metal and reduced sulfur contents. Cooling, dilution, and changes in pH of the ore fluid probably played a minor role in the precipitation of ores. The optimum results that produced the most metal sulfide deposition with the least amount of fluid was the mixing of a fluid containing low amounts of reduced sulfur with a sulfur‐rich, metal poor fluid. In this scenario, large amounts of sphalerite and galena are precipitated, together with smaller quantities of pyrite precipitated and dolomite dissolved. The relative amounts of metal precipitated and dolomite dissolved in this scenario agree with field observations that show only minor dolomite dissolution during ore deposition. The modeling results demonstrate the important control of the reduced sulfur concentration on the Zn and Pb transport capacity of the ore fluid and the volumes of fluid required to form the deposit. The studies of the Trèves ores provide insights into the ore‐forming processes of a typical MVT deposit in the Cévennes region. However, the extent to which these processes can be extrapolated to other MVT deposits in the Cévennes region is problematic. Nevertheless, the evidence for the extensive migration of fluids in the basement and sedimentary cover rocks in the Cévennes region suggests that the ore forming processes for the Trèves deposit must be considered equally viable possibilities for the numerous fault‐controlled and mineralogically similar MVT deposits in the Cévennes region.     

Chemical and isotopic signatures of Na/HCO3/CO2‐rich geofluids,North Portugal

Geochemical and isotopic studies have been undertaken to assess the origin of CO₂‐rich waters issuing in the northern part of Portugal. These solutions are hot (76°C) to cold (17°C) Na–HCO₃ mineral waters. The δ²H and δ¹⁸O signatures of the mineral waters reflect the influence of altitude on meteoric recharge. The lack of an ¹⁸O‐shift indicates there has been no high temperature water–rock interaction at depth, corroborating the results of several chemical geothermometers (reservoir temperature of about 120°C). The low ¹⁴C activity (up to 9.9 pmC) measured in some of the cold CO₂‐rich mineral waters (total dissolved inorganic carbon) is incompatible with the presence of ³H (from 1.7 to 4.1 TU) in those waters, which indicates relatively short subsurface circulation times. The δ¹³C values of CO₂ gas and dissolved inorganic carbon range between ?6‰ and ?1‰ versus Vienna‐Peedee Belemnite, indicating that the total carbon in the recharge waters is being diluted by larger quantities of CO₂ (¹⁴C‐free) introduced from deep‐seated (upper mantle) sources, masking the ¹⁴C‐dating values. The differences in the ⁸⁷Sr/⁸⁶Sr ratios of the studied thermal and mineral waters seem to be caused by water–rock interaction with different granitic rocks. Chlorine isotope signatures (?0.4‰ < δ³⁷Cl < +0.4‰ versus standard mean ocean chloride) indicate that Cl in these waters could be derived from mixing of a small amount of igneous Cl from leaching of granitic rocks.     

Children,social capital and health: increasing the well‐being of young people in rural Wales

This paper explores the usefulness of employing the concept of social capital within a research project investigating the best ways of meeting the health and well‐being needs of young people living in rural Wales. The first part of the paper provides an overview of some of the current research exploring the relationship between social capital, health and young people. The second part provides an overview of findings from an action research project to illustrate how social capital is conceived and applied in this context. It concludes by stating that children and young people do actively generate, draw upon and negotiate their own social capital, and that this is an under‐utilised resource in terms of promoting health and well‐being.     

Homelessness,poverty, and risks to health: beyond at risk categorizations of street children1

Homeless and street children are commonly portrayed in the academic and welfare literature as a prime category of ‘children at risk’. They have attracted world‐wide attention due to rising numbers in cities of the Western and developing world coupled with a discourse of childhood that ascribes risk to poor urban children unaccompanied by adults on the streets. This paper presents a critique of views about homeless and street children that rest upon an unhelpful blanket generalization of risk and, more specifically, that adopt polemical or categorical statements about homelessness as the most salient risk factor for poor health. Current research is distancing itself from a discourse that sets global characteristics for a ‘street lifestyle’, aiming instead to contextualize research on street children. Many studies have also questioned the stereotypical expectation that homeless children are the most vulnerable in deprived environments, arguing that poverty, not homelessness per se, carries the most significant risks to children's health. A risk discourse is unhelpful where it promotes a stereotype of vulnerability about children, resulting in further discrimination and social exclusion; it is most helpful when it focuses attention on ways to negotiate adverse situations. Some challenging academic and practical questions need to be raised regarding risk assumptions and risk assessment.     

PIGMENT IDENTIFICATION IN GREEK POTTERY BY RAMAN MICROSPECTROSCOPY*

Raman microspectroscopy (RMS) is now established as a key technique for the identification of pigments of archaeological pottery that permits the in situ study of art objects by a non‐destructive procedure. The information obtained represents a great aid to restoration and conservation techniques. In this work, the chemical nature of the red, black and white pigments of five samples of Greek pottery from the end of the fifth century and the first half of the fourth century bc , exhumed from the Iberian necropolis of Cabezo Lucero (Guardamar del Segura, Alicante, Spain), has been identified. The black and the red pigments are found to be magnetite (Fe₃O₄) and hematite (α‐Fe₂O₃), respectively. The white pigment is found, for the first time, to be composed of alumina (α‐Al₂O₃ and γ‐Al₂O₃) probably yielded by the thermal decomposition of Greek bauxite.