An Iron Bastard Minion Drake Extraordinary by John Browne from the Pinnace Swan (1641–53)

A small iron gun recovered from the wreck of the Caroline warship Swan has been identified as a drake, a lightweight tapered-chamber design dating from the 1620s. It is the only known cast-iron example of such a piece made by John Browne, gunfounder to Charles I, who was the leading figure in its development and manufacture in England. The gun was found together with an associated carriage, port-lid, and case shot appropriate to its calibre.
© 2004 The Nautical Archaeology Society     

Thermal convection in faulted extensional sedimentary basins: theoretical results from finite-element modeling

Thermal convection has the potential to be a significant and widespread mechanism of fluid flow, mass transport, and heat transport in rift and other extensional basins. Based on numerical simulation results, large‐scale convection can occur on the scale of the basin thickness, depending on the Rayleigh number for the basin. Our analysis indicates that for syn‐rift and early post‐rift settings with a basin thickness of 5 km, thermal convection can occur for basal heat flows ranging from 80 to 150 mW m^?2, when the vertical hydraulic conductivity is on the order of 1.5 m year^?1 and lower. The convection cells have characteristic wavelengths and flow patterns depending on the thermal and hydraulic boundary conditions. Steeply dipping extensional faults can provide pathways for vertical fluid flow across large thicknesses of basin sediments and can modify the dynamics of thermal convection. The presence of faults perturbs the thermal convective flow pattern and can constrain the size and locations of convection cells. Depending on the spacing of the faults and the hydraulic properties of the faults and basin sediments, the convection cells can be spatially organized to align with adjacent faults. A fault‐bounded cell occurs when one convection cell is constrained to occupy a fault block so that the up‐flow zone converges into one fault zone and the down‐flow zone is centred on the adjacent fault. A fault‐bounded cell pair occurs when two convection cells occupy a fault block with the up‐flow zone located between the faults and the down‐flow zones centred on the adjacent faults or with the reverse pattern of flow. Fault‐bounded cells and cell pairs can be referred to collectively as fault‐bounded convective flow. The flow paths in fault‐bounded convective flow can be lengthened significantly with respect to those of convection cells unperturbed by the presence of faults. The cell pattern and sense of circulation depend on the fault spacing, sediment and fault permeabilities, lithologic heterogeneity, and the basal heat flow. The presence of fault zones also extends the range of conditions for which thermal convection can occur to basin settings with Rayleigh numbers below the critical value for large‐scale convection to occur in a basin without faults. The widespread potential for the occurrence of thermal convection suggests that it may play a role in controlling geological processes in rift basins including the acquisition and deposition of metals by basin fluids, the distribution of diagenetic processes, the temperature field and heat flow, petroleum generation and migration, and the geochemical evolution of basin fluids. Fault‐bounded cells and cell pairs can focus mass and heat transport from longer flow paths into fault zones, and their discharge zones are a particularly favourable setting for the formation of sediment‐hosted ore deposits near the sea floor.     

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.     

Gender,the work‐life course,and livelihood strategies in a South Indian fish market

This article examines how gender ideologies differentially inform men and women's work‐life courses in the fishing economy of southern India. Drawing on interviews conducted with fish traders in Trivandrum, India in 1993–94 and 1999, we construct economic life histories for men and women traders. These are then used to illustrate how gender creates different patterns of paid work for men and women throughout their life courses and to analyze how men and women formulate livelihood strategies differently as a result.     

托忒文历史文献对清朝官方史籍编纂的影响

二十世纪三十至四十年代 ,陈垣先生曾大力倡导史源学研究。史源学的要义 ,是追寻史学论著的史料来源 ,检验立论的依据 ,考证其中的讹误。半个世纪以来 ,史源学不但在历史学界享有盛誉 ,而且扬起学术规范化的风帆 ,驶向邻近学科的学术港湾 ,产生广泛的影响。① 当然这主要讲的是对汉文文献研究的影响。在蒙文文献的研究方面 ,1 978年蒙古国学者沙·比拉在他的专著《蒙古史学史》中也关注到了这一问题。他在研究“帝国时代的蒙古史学史 (十三———十四世纪 )”的有关著述《圣武亲征录》、《元史》时就断言 ,它们的资料来源中有不少蒙古文资料…     

Isothermal Time‐Series Determination of the Rate of Diffusion of Water in Pachuca Obsidian*

Friedman and Smith's (1960) article introducing an exciting, potentially precise and inexpensive method of dating obsidian artefacts has thus far failed to reach its potential. Numerous efforts to refine, improve and even redevelop the method since that time have similarly failed to achieve the original promise. Only within the last eight years have significant improvements been made, due to both improved analytical techniques and a better understanding of the hydration process. However, most of our mechanistic understanding of the interaction of water with rhyolitic glass is based on experiments performed on melts and glasses at temperatures above their glass transitions, conditions inappropriate for investigation of near‐surface environmental conditions. Unfortunately, studies detailing the temporal evolution of the diffusion profile at low temperatures are rare, and few useful data are available on the low‐temperature diffusive hydration of silicate glasses. This paper presents data on the experimental hydration of obsidian from the Pachuca source (a.k.a. Sierra de las Navajas, Basin of Mexico) at 75°C for times ranging from 3 to 562 days, and compares these results with data for samples obtained from a stratigraphic excavation of the Chalco site in the Basin of Mexico. Samples have been analysed using secondary ion mass spectrometry (SIMS) to provide concentration/depth data. While 75°C is still significantly above the temperatures at which archaeological obsidians hydrate, it is well below the glass transition temperature (approx. 400°C) and thus processes are likely to be similar to those that occur in nature, but fast enough to be observed over a laboratory timescale. The results demonstrate that a simple square‐root‐of‐time model of the evolution of the diffusion profile is not adequate to describe the diffusion process, as measured diffusion profiles exhibit the effects of concentration‐ and time‐dependent, non‐Fickian diffusion. With progressive hydration, characteristic diffusion coefficients first decrease, then increase with time. Surface concentration increases with time, but an intermediate plateau is observed in its time evolution that is consistent with results obtained from the suite of Chalco samples. Both of these effects have been observed during diffusion in glassy polymer systems and are associated with the build‐up and relaxation of self‐stress caused by the influx of diffusing material.