Interdisciplinary research and transdisciplinary processes for environmental management under different socio-natural conditions

Interdisciplinary research and transdisciplinary processes as part of environmental management respond to the increasing complexity of socio-natural changes in recent decades. Two similar studies of eutrophication in raw water reservoirs for drinking water production in Norway and China are used to discuss interdisciplinary research and transdisciplinary processes organised through the DPSIR framework (drivers, pressures, states, impacts, and responses) as instruments for environmental management. The conclusion is that interdisciplinary research and transdisciplinary processes can enhance the understanding of complex socio-natural processes under distinctly different institutional systems. The DPSIR framework was not necessary for achieving the desired result.     

形、力与结构一段简史

在整个20世纪,无论从概念还是方法论的层面来看,结构工程师和兼任建筑师的结构工程师们针对形、力、体量彼此关系的工作方法都有了重大改变。这个改变得益于设计、工程学和建造技术的协同努力。作者雷莫·佩德雷斯基教授讨论了罗伯特．马亚尔、皮埃尔-奈尔维、爱德华多．托罗哈、菲利克斯．坎德拉、海因茨．伊斯勒和埃拉迪蒂．迪埃斯特的作品,展现了这些重要的改变和贡献,以及它们如何影响我们今天从工程学角度来理解性能的方式。     

Indoor air quality in schools of a highly polluted south Mediterranean area

This study aimed at surveying lower secondary schools in southern Italy, in a highly polluted area. A community close to an industrial area and three villages in rural areas was investigated. Indoor temperature, relative humidity (RH), gaseous pollutants (CO₂ and NO₂), selected biological pollutants in indoor dust, and the indoor/outdoor mass concentration and elemental composition of PM_2.5 were ascertained. Temperature and RH were within, or close to, the comfort range, while CO₂ frequently exceeded the threshold of 1000 ppm, indicating inadequate air exchange rate. In all the classrooms, median NO₂ levels were above the WHO threshold value. Dermatophagoides p. allergen concentration was below the sensitizing threshold, while high endotoxin levels were detected in the classrooms, suggesting schools may produce significant risks of endotoxin exposure. Concentration and solubility of PM_2.5 elements were used to identify the sources of indoor particles. Indoor concentration of most elements was higher than outdoors. Resuspension was responsible for the indoor increase in soil components. For elements from industrial emission (Cd, Co, Ni, Pb, Sb, Tl, V), the indoor concentration depended on penetration from the outside. For these elements, differences in rural vs industrial concentrations were found, suggesting industrial sources may influence indoor air quality nearby schools.     

An Electrochemical Investigation of Fe(II) Dissolved in a Cryolite Melt

Chronopotentiometric studies were made on a cryolite melt containing 3.0 wt pct Al₂O₃ and 0.466 wt pct Fe(II) at 1293 K (1020 °C). The diffusion coefficient calculated from the time of the principal chronopotentiometric transition decreased as the current density was increased, and at the same time, a second subsequent transition appeared. The diffusion coefficient calculated from this second transition was constant at 5.44 × 10^?5 cm² s^?1. The results were interpreted to show that Fe(II) in the solution exists in two forms. Fe is deposited reversibly from an active form; its exchange current density must be >1 A cm^?2. Deposition from the other form is irreversible, and it occurs directly only at high overpotentials, leading to the second transition. The equilibrium constant [active]/[inactive] = 5.4. When the equilibrium is displaced by electrolysis of the active form, the inactive form decomposes to replenish it with a rate constant of 0.9 s^?1. The Tafel curve for the direct deposition of the inactive form shows a slope of 113 mV/decade, which is interpreted as n = 2 and a symmetry factor ≈1. The exchange current density is approximately 0.3 μA cm^?2. The active and inactive forms are identified tentatively as FeF ₃ ^? and FeF ₅ ^3? , respectively.     

Applications of the closed-loop stepping motor

This paper describes a bang-bang controller which, with a particular novel scheme of discrete-state variable instrumentation, operates the stepping motor as a digital servo. The near time-optimal servomechanism is designed on a second-order basis, and the rather coarse staircase approximation of the switching curve yields good results. All control circuits have been implemented with integrated circuit components. The entire package has been product tested in the field.     

Cadmium,zinc, copper,arsenic, selenium and mercury in seabirds from the Barents Sea: levels,inter-specific and geographical differences

Trace elements Cd, Zn, Cu, As, Se and Hg were analysed in muscle and liver of Brünnich's guillemot, Common guillemot, Puffin, Black guillemot, Little auk, Razorbill, Common eider, King eider, Glaucous gull, Herring gull, Black-legged kittiwake, Northern fulmar and Arctic tern collected in 1991-1992 at the main breeding colonies in the Barents Sea. The highest levels of the most toxic elements Cd and Hg were found in birds nesting north of Spitsbergen. Extremely high levels of As were detected in tissues of all seabird species collected at colonies in Chernaya Guba (Novaya Zemlya), where nuclear tests were carried out in the 1960s. In general, levels of all of the trace elements in the Barents Sea seabirds were similar or lower in comparison with those reported for the same seabird species from the other Arctic areas. Data on metallothionein concentrations in different seabird species need to be collected in order to understand the mechanism of bioaccumulation and possible toxic effects of trace elements in Arctic seabirds.     

Bicycle-related injuries among young children related to age at debut of cycling

This study focuses on bicycle-related injuries among young children and the effect of being an inexperienced beginner related to age at debut of cycling. The study was based on a random stratified population sample of 1200 children aged 4-15 years in Bergen, Norway. Data about age at debut of cycling, cycling habits and any previous bicycle-related injuries were collected. A child was defined as a beginner within the first 12 months of active cycling. Relation between the first bicycle-related injury and age at debut was analysed by the Kaplan-Meier method. The risk of getting injured during the first 12 months of active cycling were significant lower for children aged 7 or 8 years at the debut of cycling compared to younger children (hazard ratio = 0.78, P < 0.001). Children cycling more than 1h per week were at greater risk of getting injured during the first 12 months than those who cycled less (hazard ratio = 1.95, P = 0.014). This study shows that the risk of getting injured during the first 12 months of active cycling is reduced if bicycling debut is delayed until 7 or 8 years instead of at 4 or 5 years.