Ecological economics: themes, approaches, and differences with environmental economics

This article provides a short overview of the main themes of ecological economics (EE). It is argued that EE provides a platform that fosters multidisciplinary environmental research by bringing together the core contributing disciplines – economics and ecology. In addition, EE is regarded as a pluralistic approach to environmental research that can be set opposite to, and has indeed developed as a response to, traditional environmental and resource economics. A comparison of the two fields is presented to clarify the essential differences between them. In addition, specific themes are examined in more detail. These include: sustainable development; the growth debate; international trade; dynamic processes; and behaviour and policy. Electronic Publication     

Increased incidence of cytogenetic abnormalities in chorionic villus samples from pregnancies established by in vitro fertilization and embryo transfer (IVF–ET)

We studied 201 pregnancies that were established by in vitro fertilization and embryo transfer (IVF–ET) and compared the frequency of cytogenetic abnormalities with that found in a large control population matched for indication group (advanced maternal age) and time of sampling. A total of 252 IVF–ET fetuses were cytogenetically analysed by either chorionic villus sampling (CVS; n = 80) or amniocentesis (n = 172). Eleven chromosome abnormalities were found in the CVS group (13·8 per cent); among them, a 45, X/46, X, dic(q11)/46, X, del(Y)(q11) mosaic that was found in an IVF pregnancy established by intracytoplasmic sperm injection (ICSI), four cases of trisomy 21, and three cases of trisomy 7 confined to the placenta. The results indicate a statistically significant three-to five-fold increase in both confined placental abnormalities (P<0·008) and true fetal chromosome anomalies (P<0·04). In the amniocentesis group, identical rates (1·7 per cent) of chromosome abnormalities were found in the IVF–ET and control groups. It is concluded that late first trimester, but not early second trimester, IVF–ET pregnancies are characterized by an increased frequency of cytogenetic abnormalities found at prenatal diagnosis.     

探究式教学模式下物理实验的设计与实现

随着新的教育、教学技术的不断涌现和新的教学模式的提出,传统的实验教学模式已经不能满足现代素质教育的要求,急需新的更为先进的教学模式来提高实验教学的效果。在此背景下,笔者通过研究探究式教学模式,并将此模式应用到大学物理实验教学中,取得了良好的效果。     

UASB反应器处理造纸废水不同高度的污泥特性

为探讨上向流污泥床（UASB）反应器不同高度处的污泥特性,研究了生产性UASB反应器（总高7.2m）处理造纸废水时不同高度的污泥外观形态、稳定性及其产甲烷活性.结果显示,VS、TS、VSS、TSS浓度随着在反应器中取样高度的增加逐渐降低,并在距离反应器底部2.20m高度处出现分层.反应器1.20m和3.45m高度处的溶解性COD值较大（900mg·L-1以上）.反应器1.20m处污泥的稳定性较好（VS/TS较低）,固体浓度较高（TS136g·L-1,VS75g·L-1）,产甲烷活性较高（0.16g·g-1·d-1,以每gVSS中的COD计）,颗粒较大（平均当量直径为308μm）.UASB反应器处理造纸废水不同高度的污泥颗粒外观形态虽有差异,但污泥的生物活性近似.     

Measurement method for objective cyclist behavior parameters

Abstract

Objective: The objective of this research is to study the feasibility of measuring behavioral indicators that reflect effects of infrastructure and interaction with other road users.

Methods: An observation study was performed using 6 cameras above a separated cycle path next to a road which included a crossing with both cyclists and cars. A learning method based on Single Shot MultiBox Detector was applied to automatically detect the cyclists, and cyclist tracks were determined. Next, kinematic parameters were calculated from the cyclists’ tracks. Amongst others, the cyclists’ intensity, speed, position on the cycle path, and the distance to each other were analyzed for a busy period as well as for a quiet period of the day.

Results: With the measurement method developed in this study it is possible to analyze the cyclists’ intensity, the space they use at the cycle path, their average velocity, waiting times, the space and velocity amongst each other, and red light negation. However, collisions were not seen in the dataset analyzed, and the data is not sufficiently accurate to analyze sudden braking actions.

Conclusion: It can be concluded that the developed measurement method provides insight of the cyclists’ behavior in such a way that it can already be used for obtaining information to make changes to the infrastructure that will improve the comfort and safety of cyclists. The method could be further developed for doing qualitative comfort and safety analyses, and for doing analyses of the interaction between various types of road participants.     

Crimson-breasted Shrike females with extra pair offspring contributed more to duets

Many socially monogamous bird species follow a genetically promiscuous reproductive strategy. Duetting birds may be an exception, as they appear to exhibit very low levels of extra pair paternity—which is thought to be connected to duetting. Duets are predicted to function either in paternity guarding or as signals of commitment to the pair bond, reciprocally reducing extra pair mating in both sexes. In this study, we used four microsatellites to document paternity loss in the Crimson-breasted Shrike (Laniarius atrococcineus), a socially monogamous subtropical duetting species. Extra pair paternity was surprisingly high, with extra pair males siring 20 % of young in 30 % of broods. Furthermore, we compared the levels of extra pair paternity of each pair to certain characteristics of their duets to test the paternity guard and the commitment hypotheses. Our results offered no support that duets function in paternity guarding, although the fact that males which had been cuckolded answered more of their female’s calls could represent an adaptation to avoid future cuckoldry. We also found no evidence for duets functioning as signal of commitment. Female vocal behaviour was in fact the reverse of that predicted: Levels of infidelity amongst social females were positively related to female answer rate of their mates’ songs. These results indicate that females may use increased answer rates as a form of manipulation, in an attempt to avoid potential costs associated with their extra pair matings.     

Long Term NH3 Flux Measurements above Grasslands in The Netherlands

Ammonia concentration gradients were measuredabove a grassland in an agricultural region fromJuly 1998 to July 2000 at the locationSchagerbrug in the Netherlands. They were used tocalculate the surface-atmosphere exchange ofammonia by means of the aerodynamic gradienttechnique. Measurements of the ammonia exchangewere also performed at a grass field that is partof a major wetland reserve in the centre of theNetherlands (Oostvaardersplassen), during theperiod June 1994–September 1995. At Schagerbrug,low net emissions or small depositions weremeasured during the winter months, and a netemission up to 5 kg NH₃ ha^-1 month^-1 in summer. The net annual emission was 26 kgN ha^-1, with manure application contributingabout 50% of this emission. AtOostvaardersplassen mainly deposition occurred,but large emissions were measured in autumn. Themeasured exchange fluxes are compared to modelevaluations that incorporate plant physiologicaldata, such as apoplastic NH₄ ⁺concentrations and pH. Results show a goodagreement between field observations and modelsimulations, although some improvements arenecessary during nighttime periods. Themeasurements are conducted within the GRAMINAEproject, a second tranche project of EC TERI.     

Expansion-controlled evaporation: a safe approach to BLEVE blast

A new method is presented to calculate the blast effects originating from an exploding vessel of liquefied gas. Adequate blast calculation requires full knowledge of the blast source characteristics, i.e., the release and consequent evaporation rate of the flashing liquid. As the conditions that allow explosive evaporation are not entirely clear and the evaporation rate of a flashing liquid is unknown, safe assumptions are the starting point in the modelling. The blast effects from a BLEVE are numerically computed by imposing the vapour pressure of a flashing liquid as boundary condition for the gas dynamics of expansion. The numerical modelling is quantitatively explored just for liquefied propane. In addition, it is demonstrated that often an estimate of BLEVE blast effects is possible with very simple acoustic volume source expressions.

The modelling shows that the rupture of a pressure vessel containing a liquefied gas in free space only develops a blast of significant strength if the vessel nearly instantaneously disintegrates. Even if a rupture and the consequent release and evaporation of a liquefied gas extend over just a short period of time, the blast effects are minor.     

Maternal transfer of organochlorines and brominated flame retardants in blue tits (Cyanistes caeruleus)

Although eggs have frequently been used as a biomonitoring tool for contamination with organohalogenated pollutants (OHPs), few studies have investigated the processes of maternal transfer in birds. Here, maternal transfer of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was investigated through comparison of the concentrations and profiles between whole homogenised female blue tits (Cyanistes caeruleus) and their eggs. In addition, we examined if there was an effect of laying order on the concentrations of PCBs, OCPs and PBDEs. PCBs were the most abundant contaminants in female blue tits and their eggs, followed by OCPs and PBDEs. Among the OCPs, p,p'-DDE was the most dominant compound and accounted for more than 80% of the sum OCPs. Egg concentrations decreased significantly in relation to the laying order from 1623+/-148 ng/g lipid weight (lw) to 1040+/-47 ng/g lw for the sum PCBs, from 342+/-24 ng/g lw to 235+/-17 ng/g lw for the sum OCPs and from 49+/-5 ng/g lw to 27+/-5 ng/g lw for the sum PBDEs. When reviewing all studies investigating laying order effects of OHPs in birds, no clear patterns emerged, which may be due to differences in study species and methodology among studies. Despite the fact that there were laying order effects in blue tit clutches, the variance in concentrations of PCBs and PBDEs was larger among clutches than within clutches. Variance in OCP concentrations among clutches was similar to the variance within clutches. These results suggest that one randomly collected blue tit egg from a clutch is useful as biomonitoring tool for PCBs and PBDEs, while for OCPs it is recommended to consistently use the same egg from the laying sequence as a biomonitoring tool. Lipid-normalized concentrations of sum PCBs, sum OCPs and sum PBDEs in female blue tits after clutch completion were comparable to the concentrations in the first-laid eggs. The egg/female lipid concentration ratios for sum PCBs, sum OCPs and sum PBDEs decreased significantly from 1.0+/-0.09 to 0.7+/-0.003, 1.1+/-0.1 to 0.7+/-0.02 and 1.2+/-0.14 to 0.8+/-0.05, respectively, during the course of egg laying. The profiles of the females and eggs differed significantly for the PCBs, OCPs and PBDEs. There was a higher contribution of lower chlorinated PCB congeners (CB 28, CB 52, CB 95, CB 101 and CB 110), BDE 183, p,p'-DDT and other less persistent OCPs in the females compared to their eggs. Maternal transfer in blue tits seemed to be selective for the more bioaccumulative and persistent congeners/compounds.