Crown density assessments, control surveys and reproducibility

This study aims to evaluate the quality of crown density data, based on independent, pairwise tree assessments. The data originates from monitoring of forest health (crown condition) in Norway; 250 plots, comprising 12 000 individual trees of Norway spruce, have been reassessed by a single observer during 1990–95. Of the trees, 2300 were controlled more than twice, providing the possibility of evaluating the quality of assessed temporal changes of crown density. True errors (standard deviation) are estimated to be about 10% for single trees and 5% for plot means, while the real standard deviation of the differences were slightly higher. The errors of the temporal changes of crown density were of similar magnitude. Systematic differences in crown density were found between sites and plot types, partly resulting from observer bias. However, the results suggest that observer bias is really the result of each observer's personal style in assessment.     

Solid-phase microextraction coupled with atomic emission spectroscopy--rapid screening for volatile chlorinated compounds

Solid-phase microextraction (SPME) coupled with atomic emission spectroscopy was evaluated as a rapid screening tool for volatile halogenated compounds in water samples. After extraction, the SPME fiber was introduced to the injector where the analytes were rapidly and efficiently desorbed. The analytes entered the detector over a short period of time and produced one well-defined analyte signal. Element selective responses were measured to confirm the presence and to roughly estimate the content of volatile compounds. The total time for extraction and detection was approximately 5 min, which makes this method a rapid and promising technique for determination of total amount of volatile halogenated compounds. The proposed technique may prove useful as a screening test in order to pinpoint the samples that need further assessment by capillary gas chromatography.     

Crown condition of Norway spruce in relation to sulphur and nitrogen deposition and soil properties in southeast Norway

Atmospheric deposition of sulphur and nitrogen compounds may lead to enhanced leaching of base cations, accumulation of nitrogen in organic matter, lowered pH and increased concentration of toxic aluminium in soil, which in turn may affect the vitality of forest trees. A general monitoring of forest condition has been initiated in many European countries, partly in order to reveal stresses caused by acidification. However, forest condition is also affected by many other factors. This paper examines a seven-year series of crown-condition data from Local County Monitoring Plots in Norway spruce stands in Norway. Average, time trend and lability variables were calculated for crown density and crown colour for each plot. Wet deposition of sulphate, ammonium and nitrate for each plot were estimated using data from the national air and precipitation monitoring programmes. Soil data are based on soil sampling within the plots. The analysis gave no evident support for the hypothesized negative effect on crown condition from sulphur and nitrogen deposition and related alterations in soil.     

Comparison of multibody and finite element human body models in pedestrian accidents with the focus on head kinematics

Objective: The objective of this study was to compare and evaluate the difference in head kinematics between the TNO and THUMS models in pedestrian accident situations.

Methods: The TNO pedestrian model (version 7.4.2) and the THUMS pedestrian model (version 1.4) were compared in one experiment setup and 14 different accident scenarios where the vehicle velocity, leg posture, pedestrian velocity, and pedestrian's initial orientation were altered. In all simulations, the pedestrian model was impacted by a sedan. The head trajectory, head rotation, and head impact velocity were compared, as was the trend when various different parameters were altered.

Results: The multibody model had a larger head wrap-around distance for all accident scenarios. The maximum differences of the head's center of gravity between the models in the global x-, y-, and z-directions at impact were 13.9, 5.8, and 5.6 cm, respectively. The maximum difference between the models in head rotation around the head's inferior–superior axis at head impact was 36°. The head impact velocity differed up to 2.4 m/s between the models. The 2 models showed similar trends for the head trajectory when the various parameters were altered.

Conclusions: There are differences in kinematics between the THUMS and TNO pedestrian models. However, these model differences are of the same magnitude as those induced by other uncertainties in the accident reconstructions, such as initial leg posture and pedestrian velocity.     

MPA in Labor: Securing the Pearl Cays of Nicaragua

Implementation of Marine Protected Areas (MPAs) has always a step-zero, i.e., an initial phase when the idea is incepted, communicated and negotiated among stakeholders. What happens during this phase is likely to have an impact later on. If not done right, the management of the MPA may encounter problems at later stage that will be difficult to correct. Inspired by this working theory, this article describes the effort to establish the Pearl Cays off the Caribbean coast of Nicaragua as a protected area. This case-study illustrates the critical actions to be taken during step-zero, i.e., what needs to be considered and done before an MPA is formally declared. The area investigated consists of a number of small islands (cays) and coral reefs, fishing grounds and marine turtle nesting areas. Throughout history, the cays have played an important role in sustaining livelihoods of nearby communities. Although the idea of an MPA was originally conservation, the communities saw it as an opportunity to regain ownership and control of the cays. By Nicaraguan law, in order to establish protected areas, consultation and approval from local people is required. In the case of the Pearl Cays, this has proved difficult. The article demonstrates how MPA initiatives must sometimes relate to already ongoing complex social processes in the area where they are to be instigated.     

Safety climate and hydrocarbon leaks: An empirical contribution to the leading-lagging indicator discussion

Hydrocarbon (HC) leaks are important initiating events for major accidents in the oil and gas industry. This study explores the extent to which a safety climate indicator from a survey on working conditions undertaken in an oil and gas company (n = 2188) can be used as a leading and/or lagging indicator in relation to HC leaks on 28 offshore installations. It was found that more negative safety climate scores were associated with increasing numbers of HC leaks over a 12-month period following the survey. The safety climate indicator explained more of the variance in HC leaks than technical indicators. HC leaks in the 12-month period preceding the survey did also correlate significantly with the safety climate indicator. More HC leaks during this period were associated with worse scores on the safety climate indicator. Thus, the results support that the safety climate measure could serve as leading and lagging indicator for HC leaks. The results and their possible implications are discussed.     

The Role of Wood Material for Greenhouse Gas Mitigation

Based on an interdisciplinary perspective the role of wood as a carbon sink, as a multi-purpose material, and as a renewable energy source for the net reduction of greenhouse gases is discussed. We synthesize aspects from engineering, natural and social sciences to better understand the role of wood substitution in CO₂ mitigation. We also formulate some recommendations on filling knowledge gaps that could be useful for policy making regarding how wood substitution could be further expanded. There are sufficient wood resources to substantially increase the use of wood for material and energy purposes. However, a number of factors hinder a wider use of wood for energy and material purposes. Furthermore, an analysis of wood substitution is a very complex issue, since the substitution influencing factors are to be found along the entire wood supply chain and involve several industries, socio-economic and cultural aspects, traditions, price dynamics, and structural and technical change. To improve the knowledge about wood as a substitute for other resources and the implications, it would be helpful to better integrate research from different disciplines on the subject and to cover different scales from a project to an economy-wide level.     

从全球角度看欧洲削减地面臭氧

欧盟(EU)的"欧洲清洁空气"计划(Clean Air for Europe,CAFE)目前正在对大气质量政策进行修订,这将促使欧盟在2005年中期实行的第六期环境行动计划(Environmental Action Programme)中采取针对大气污染的专题策略.