Testing taxonomic resolution,data transformation and selection of species for monitoring macroalgae communities

The Water Framework and Habitats Directives require the evaluation of both the conservation and ecological status of macroalgae communities at water body or habitat level. However, assessments of macroalgal communities are highly time-consuming, both in terms of sampling effort and laboratory processing. These constraints have brought about their oversight in many marine monitoring programs, especially in subtidal environments. By using data from intertidal and subtidal macroalgae assemblages of Mouro Island (North coast of Spain) we wanted to identify possible cost-effective methods for monitoring this biological indicator, based on both high taxa levels and use of representative taxa. Multivariate analyses were applied using different data transformations. The results show that macroalgal communities are robust to aggregation to genus or even family level. Moreover, the outcomes show that transformation types introduce higher variation in the multivariate pattern of samples than the taxonomic level to which organisms are identified. Also, the study supports the use of representative taxa as a surrogate to overall community structure. Therefore, we conclude that a rapid-assessment by means of field evaluations, based on coverage of representative taxa, is a reliable alternative for the assessment of macroalgae status. In addition this procedure allows evaluation at a broader spatial scale (water body or habitat level) than traditional quantitative sampling procedure does.     

Marginal abatement cost curves: a call for caution

Legal commitments to reduce CO₂ emissions require policy makers to find cost-efficient means to meet these obligations. Marginal abatement cost (MAC) curves, which illustrate the economics associated with climate change mitigation, have recently attracted a great amount of attention. A number of limitations with MAC curves are explained by the implication they should be just one tool in a broader set of decision-making aids used in assessing climate policy. MAC curves, for example, omit ancillary benefits of greenhouse gas emission abatement, treat uncertainty in a limited manner, exclude intertemporal dynamics and lack the necessary transparency concerning their assumptions. MAC curves based on the individual assessment of abatement measures suffer from additional shortcomings such as the non-consideration of interactions and non-financial costs, a possibly inconsistent baseline, double counting and limited treatment of behavioural aspects. Reducing emissions from deforestation and forest degradation exhibit many of the above-mentioned problems, making it particularly difficult to capture in a cost curve. Policy makers should therefore be cautious when interpreting MAC curves, pay attention to the underlying assumptions, consider non-financial costs and be aware of the important uncertainties and underlying path dependencies.     

Stabilizing CO2 concentrations with incomplete international cooperation

Many stabilization scenarios have examined the implications of stabilization on the assumption that all regions and all sectors of all of the world's economies undertake emissions mitigations wherever and whenever it is cheapest to do so. This idealized assumption is just one of many ways in which emissions mitigation actions could play out globally, but not necessarily the most likely. This paper explores the implications of generic policy regimes that lead to stabilization of CO₂ concentrations under conditions in which non-Annex I regions delay emissions reductions and in which carbon prices vary across participating regions. The resulting stabilization scenarios are contrasted with the idealized results. Delays in the date by which non-Annex I regions begin to reduce emissions raise the price of carbon in Annex I regions relative to the price of carbon in Annex I in an idealized regime for any given CO₂ concentration limit. This effect increases the longer the delay in non-Annex I accession, the lower the non-Annex I carbon prices relative to the Annex I prices, and the more stringent the stabilization level. The effect of delay is very pronounced when CO₂ concentrations are stabilized at 450 ppmv, however the effect is much less pronounced at 550 ppmv and above. For long delays in non-Annex I accession, 450 ppmv stabilization levels become infeasible.     

PET/CT新技术应用

PET/CT将PET与CT整合为一体化,是功能显像和解剖显像的有机结合.为了获取经济效益,PET/CT必须在不增加治疗费用的同时具有精确的诊断性,并对患者的治疗方案作出有效的指导.PET/CT由于采用了3D采集与单纯PET相比缩短了图像采集时间,从而使病人的要求得到更大程度的满足,同时也增加了病人的舒适程度,减少了由于采集过程中病人活动导致的出错机率.PET/CT在临床上主要应用于肿瘤学、心脏病学及神经精神医学等领域,在上述领域的中其诊断精确性优势是其他显像方法不可比拟的.在指导肿瘤治疗方面,PET/CT可以通过改善患者的治疗决策而具有重要的卫生经济学价值.     

Improvement of very soft ground by a high-efficiency vacuum preloading method: A case study

This paper describes a full-scale test on a very soft clay ground around 70,000?m², which is conducted in Huizhou of Guangdong Province, China, to present a new method of vacuum preloading method. A novel moisture separator was developed, which can automatically regulate the vacuum pressure variation by changing the volume of the gas inside it. A large quantity of water drained by the proposed moisture separators can be directly used as a surcharge loading, which would shorten the ground improvement time and save costs as well. Three levels of silt-prevention prefabricated vertical drains were used in the treating process to accelerate the consolidation. In addition, the vacuum preloading method also included an effective radial drainage device which would strengthen the dredged soft clay fill in a deep layer. In the in situ test, tens of piezometers and settlement plates were installed to measure the variations of excess pore water pressures and settlement of two stages of observation points at different positions in the ground. The results show that the largest average consolidation settlement was 314.1?cm and made a saving of more than 66% in power consumption compared with traditional method. It demonstrates that this adopted method is an efficient, cost-effective, and environmentally friendly method for improving sites with low bearing capacity and high compressibility soils.     

基于价值工程的地震安全社区经济性决策分析

近几年地震频繁发生,为有效预防地震灾害,我国大力推进地震安全社区建设。运用价值工程原理对地震安全社区和普通建设小区的成本和效益进行对比分析,建立价值工程模型,并结合实例验证:增加少量成本建设地震安全社区,可以大幅度增加社会效益和经济效益,为地震安全社区的推广建设提供科学依据。     

灌注桩工程成本价值工程分析

以灌注桩为例 ,对灌注桩成本进行了价值工程分析并结合A、B、C分类管理和目标成本管理等现代化管理方法、系统地指出了降低灌注桩工程成本的途径。     

中国城市LID技术设施的成本效益区域差异

随着城市化进程不断加快,人口和城市规模不断扩张,对现代城市雨洪管理提出了新要求。本文运用情景分析法研究中国城市典型低影响开发(Low Impact Development, LID)技术设施的成本效益。分别以80%与95%降雨场次控制率对应的场次降雨为情景,以30年为服务期计算技术设施的雨水管理效益。研究发现：北方城市的建安成本与维护费用均值高于南方城市,同时受区域降雨量差异的影响,南方城市LID技术设施的雨水处理效益普遍高于北方。而北方城市之间效益差异亦较大,其中京津冀地区及西北地区的城市雨水处理效益尤低。不同技术设施之间差异表现为：原地入渗设施的雨水处理成本在6~188元/m3之间,显著高于具有汇流功能的设施。对降水较少的北方城市建议采用成本低、效果好的下沉式绿地结合雨水湿地的方式;对雨量大、雨强高的南方城市建议采用生物滞留设施结合调节塘的方式,可增大调蓄能力达到降雨场次控制率的要求,同时能够净化地面径流、增强雨水下渗。     

Is there a role for potential supervised injection facilities in Victoria,British Columbia,Canada?

Supervised injection facilities (SIFs) are medical facilities where injection drug users can inject their illicit drugs under the supervision of nurses and doctors. Currently, there is only one legal SIF in operation in North America and it has been operating in Vancouver, British Columbia for over a decade. The purpose of this study is to determine whether the current facility needs to be expanded to other locations in British Columbia, Canada. We employ mathematical modeling to estimate the number of new human immunodeficiency virus (HIV) and hepatitis C infections prevented based on the available secondary data. Additionally, we also estimate the number of prevented overdose deaths attributable to the SIF. With very conservative estimates, it is predicted that establishing two SIFs locations outside Vancouver in British Columbia’s capital city, Victoria, is cost-effective, with a benefit-cost ratio of 1.25:1. It appears that expanding SIFs to Victoria could offer significant savings for local health care institutions.