Palaeolimnological validation of estimated reference values for a lake profundal macroinvertebrate metric (Benthic Quality Index)     

Jussi Jyväsjärvi  Jukka Nyblom  Heikki Hämäläinen 《Journal of Paleolimnology》2010,44(1):253-264

Modern assessment and monitoring of aquatic ecosystems is increasingly based on biota and the “reference condition” approach, in which the observed values (O) of biological variables are compared to those expected in the absence of human disturbance (E). To use this approach, correct estimation and validation of reference conditions are critical. Because appropriate modern or historical data are never available for this approach, palaeolimnological data offer an alternative. We used a calibration data set from 73 profundal sites in semi-pristine Finnish lakes to construct a regression model for estimating expected values for the chironomid Benthic Quality Index (BQI)—a macroinvertebrate metric widely used in bioassessment—from environmental variables that are insensitive to human disturbance. For comparison, reference values were estimated using the European legislative rationale based on a priori lake typology. Performance of the alternative approaches was assessed by internal ‘leave-one-out’ cross-validation using the calibration set and by external cross-validation using independent palaeolimnological data on BQI values representing the historical pristine status of 24 lake basins. Additionally, for 19 of these sites, which vary in their degree of human impact, the ratio of present BQI to that in pristine condition, which shows the degree of actual change, if any, was calculated from palaeolimnological data and compared with the O/E ratios based on the present chironomid data and estimated E. A linear regression model with mean depth and mean/maximum depth ratio as independent variables estimated the reference values of BQI much closer to the observed ones (r ² = 0.58, RMSEP = 0.65 and r ² = 0.71 RMSEP = 0.55; for internal and external cross-validation, respectively) than did the typology approach (r ² = 0.28, RMSEP = 0.86; r ² = 0.10, RMSEP = 0.97). The regression approach also yielded O/E ratios more similar to the actual ones (r ² = 0.79, RMSEP = 0.09) than did the typology approach (r ² = 0.62, RMSEP = 0.23). Our results strongly support the use of lake morphometric variables and modelling instead of categorical lake typology for the establishment of reference conditions for profundal macroinvertebrate communities and demonstrate the utility of palaeolimnological data in the validation of reference values and assessment methods.  相似文献   

Cs studies of dense cores in regions of high mass star formation: a survey of southern molecular masers     

I. Zinchenko  A. Lapinov  K. Mattila  M. Toriseva 《Astrophysics and Space Science》1995,224(1-2):585-586

We searched for the CSJ = 2 – 1 emission towards 29 southern H₂O and H₂O/OH masers and 1 OH maser with the SEST radio telescope. We detected and mapped 24 CS emitting regions probably associated with 27 H₂O masers. The C³⁴SJ = 2 – 1 and COJ = 1 – 0 lines were also observed at the grid positions closest to the CS peaks. Four cores were mapped in the CSJ = 5 – 4 and C³⁴SJ = 2 – 1 lines.  相似文献   

CO2-induced climate change in northern Europe: CMIP2 versus CMIP3 versus CMIP5     

Jouni Räisänen  Jussi S. Ylhäisi 《Climate Dynamics》2015,45(7-8):1877-1897

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Mineral chemical evidence for extremely magnesian subalkaline melts from the Antarctic extension of the Karoo large igneous province     

Jussi S. Heinonen  Arto V. Luttinen 《Mineralogy and Petrology》2010,99(3-4):201-217

We present a comprehensive mineral chemical dataset (～400 analyses) on subalkaline meimechitic (Mg-number?=?74–80) and ferropicritic (Mg-number?=?67–69) dike samples from the Antarctic extension of the Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. Some of the meimechites, previously considered to be cumulates from ferropicritic magmas, are characterized by forsteritic olivine (with core composition up to Fo₉₂) that is in, or close to Fe-Mg equilibrium with the host rock. The olivines are subhedral to euhedral, contain Ti-rich (volcanic) spinel inclusions, have a high CaO content (≥0.19 wt. %), and are thus unlikely to represent xenocrysts from mantle peridotite. Igneous amphibole is found in olivine-hosted, crystallized melt inclusions, indicating that the parental magmas had a H₂O content of 1–2 wt. %. The olivine data suggests generation of extremely MgO-rich (up to 25 wt. %) melts during the Karoo magmatism. Based on our petrogenetic modeling, such melts are likely to have originated from the partial melting of garnet peridotite at high pressures (5–6 GPa) and mantle potential temperatures (>1,600°C) that are compatible with the involvement of a mantle plume in the generation of the Karoo LIP. A geochemical comparison of the Vestfjella meimechites with meimechites from the Siberian Traps LIP and the assumed komatiitic parental melts of the Horingbai picrites (Paraná-Etendeka LIP) reveals key similarities, suggesting that all these suites were generated from broadly similar sources and/or by similar melting processes in anomalously hot subcontinental mantle.  相似文献   

Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments   总被引：1，自引：1，他引：0  

Hui Tang  Arne Micheels  Jussi T. Eronen  Bodo Ahrens  Mikael Fortelius 《Climate Dynamics》2013,40(5-6):1531-1549

It has been demonstrated in climate models that both the Indian and East Asian summer monsoons (ISM and EASM) are strengthened by the uplift of the entire Asian orography or Tibetan Plateau (TP) (i.e. bulk mountain uplift). Such an effect is widely perceived as the major mechanism contributing to the evolution of Asian summer monsoons in the Neogene. However, geological evidence suggests more diachronous growth of the Asian orography (i.e. regional mountain uplift) than bulk mountain uplift. This demands a re-evaluation of the relation between mountain uplift and the Asian monsoon in the geological periods. In this study, sensitivity experiments considering the diachronous growth of different parts of the Asian orography are performed using the regional climate model COSMO-CLM to investigate their effects on the Asian summer monsoons. The results show that, different from the bulk mountain uplift, the regional mountain uplift can lead to an asynchronous development of the ISM and EASM. While the ISM is primarily intensified by the thermal insulation (mechanical blocking) effect of the southern TP (Zagros Mountains), the EASM is mainly enhanced by the surface sensible heating of the central, northern and eastern TP. Such elevated surface heating can induce a low-level cyclonic anomaly around the TP that reduces the ISM by suppressing the lower tropospheric monsoon vorticity, but promotes the EASM by strengthening the warm advection from the south of the TP that sustains the monsoon convection. Our findings provide new insights to the evolution of the Asian summer monsoons and their interaction with the tectonic changes in the Neogene.  相似文献   

Aesthetic justice and urban planning: Who ought to have the right to design cities?*     

Hanna Mattila 《GeoJournal》2002,58(2-3):131-138

This paper brings together two diverse approaches to urban planning. The first approach views planning as a means to distribute goods or welfare in society, and therefore considers the promotion of social justice to be the central objective of planning. The second approach highlights the role of planning as a means to produce aesthetically pleasing everyday surroundings. I will explore the concepts of `aesthetic welfare' and `aesthetic justice' developed by the philosopher Monroe Beardsley, and argue that an aesthetically pleasing environment is an important source of aesthetic welfare in society. My contention, then, is that the fair distribution of this welfare should be one of the objectives of public planning policies. This objective, however, is difficult to achieve, since the question cannot only concern the distribution of the aesthetically good environment. This is because there often is no agreement on the criteria for the aesthetically good environment. Thus, I will eventually reject the idea of aesthetic justice as distributive justice that Beardsley advocates. Instead, I will turn to some contemporary theories of justice that question the model of distributive justice, arguing that theories of justice should go beyond the distribution of goods, and encompass also the conception and production of goods. Thus, as I will maintain, aesthetic justice will be eventually best promoted by opening the aesthetic dimension of urban planning (among other dimensions of it) to public participation.  相似文献   

Evaluation of delta change and bias correction methods for future daily precipitation: intermodel cross-validation using ENSEMBLES simulations   总被引：1，自引：0，他引：1  

Olle Räty  Jouni Räisänen  Jussi S. Ylhäisi 《Climate Dynamics》2014,42(9-10):2287-2303

Due to inherent limitations in climate models, their output is biased in relation to observed climate and as such does not provide reliable climate projections. In this study, nine methods used to account for biases in daily precipitation are tested. First, cross-validation tests were made using a set of ENSEMBLES regional model simulations to gain insights in the potential performance of the methods in the future climate. The results show that quantile mapping type methods, being able to modify the shape of the precipitation distribution, often outperform other types of methods. Yet, as the performance depends on time of the year, location and part of the distribution considered, it is not possible to distinguish one universally best performing method. In addition, the improvement relative to the projections that would have been obtained assuming unchanged climate is relatively modest, particularly in the early twentyfirst century conditions. Further tests with different method combinations show that the projections could be potentially improved by using several well performing methods in parallel. In the second part of the study, contributions of method and model differences to the overall variation of precipitation projections are assessed. It is shown that although intermodel differences play an important role, uncertainties related to intermethod differences are substantial, particularly in the tails of the distribution. This suggests that method uncertainty should be taken into account when constructing daily precipitation projections, possibly by using several methods in parallel.  相似文献   

Displacement barrier heights from experimental nucleation rate data     

Jussi Malila  Antti-Pekka Hyvrinen  Yrj Viisanen  Ari Laaksonen 《Atmospheric Research》2008,90(2-4):303-ICNAA07

Nucleation phenomena have a great importance in many areas of science. However, the main theoretical tool to analyse these phenomena, the classical nucleation theory (CNT), has known weaknesses. A decade ago a nucleation theorem based correction to CNT was developed [McGraw, R., Laaksonen, A., 1996. Scaling properties of the critical nucleus in classical and molecular-based theories of vapor–liquid nucleation. Phys. Rev. Lett. 76, 2754–2757]. We have analysed experimental nucleation rate data of two homologous series of molecular fluids in terms of this scaling relation. Our first results suggest possible universal functional form for correction to the temperature dependence of CNT.  相似文献   

线阵探测器(LDA)的现状及发展趋势   总被引：7，自引：1，他引：7  

J·柯斯克能  蔺春涛  高冬 《CT理论与应用研究》2002,11(3):12-15

本文概述了当前的线阵探测器(LDA)技术及未来发展，同时详细说明了LDA的重要性能特征，并对不同应用下不同的阵列设计进行了讨论。目前芬兰探测技术公司已将该项技术成功应用于大型集装箱检测系统，工业CT，医用CT，L型双能探测器等工业医学应用中．  相似文献   

Key site variables governing the functional characteristics of Dissolved Natural Organic Matter (DNOM) in Nordic forested catchments   总被引：1，自引：0，他引：1  

Rolf D. Vogt  Jarkko Akkanen  Dag Olav Andersen  Rainer Brüggemann  Bimal Chatterjee  Egil Gjessing  Jussi V. K. Kukkonen  Håkon E. Larsen  Jörg Luster  Andrea Paul  Stephan Pflugmacher  Mike Starr  Christian E. W. Steinberg  Philippe Schmitt-Kopplin  Ádám Zsolnay 《Aquatic Sciences - Research Across Boundaries》2004,66(2):195-210

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