城市生态景观研究的基础理论框架与技术构架

构建人与自然和谐的生态景观是当今城市发展的重要目标之一,统一的内涵和完善的指标体系是城市生态景观规划和设计的迫切需求。通过概括城市生态景观的基本内涵和主要特征,认为其核心价值包括可持续性、生态经济效益及和谐性。据此,提出了8条指导原则,包括景观自然度、物种安全性和多样性、雨水利用效率、污染物排放和处理、绿色能源和材料利用、局地小气候调节、景观视觉享受以及精神内涵和文化品位,并根据文献资料和行业导则,整理并归纳了有关的定量评价指标和适用范围。最后总结了城市生态景观的技术构架,以及在资源保护和节约、功能与形式的有机结合、系统生态价值最大化等方面亟待解决的关键技术。为城市生态景观研究提供基础理论框架,也可以为城市生态景观的具体实践提供参考。     

Cost of reproduction in the Queensland fruit fly: Y-model versus lethal protein hypothesis

The trade-off between lifespan and reproduction is commonly explained by differential allocation of limited resources. Recent research has shown that the ratio of protein to carbohydrate (P : C) of a fly''s diet mediates the lifespan–reproduction trade-off, with higher P : C diets increasing egg production but decreasing lifespan. To test whether this P : C effect is because of changing allocation strategies (Y-model hypothesis) or detrimental effects of protein ingestion on lifespan (lethal protein hypothesis), we measured lifespan and egg production in Queensland fruit flies varying in reproductive status (mated, virgin and sterilized females, virgin males) that were fed one of 18 diets varying in protein and carbohydrate amounts. The Y-model predicts that for sterilized females and for males, which require little protein for reproduction, there will be no effect of P : C ratio on lifespan; the lethal protein hypothesis predicts that the effect of P : C ratio should be similar in all groups. In support of the lethal protein hypothesis, and counter to the Y-model, the P : C ratio of the ingested diets had similar effects for all groups. We conclude that the trade-off between lifespan and reproduction is mediated by the detrimental side-effects of protein ingestion on lifespan.     

The derivation, performance and role of univariate and multivariate indicators of benthic change: Case studies at differing spatial scales

In Europe there is an extensive history of the derivation and use of benthic indicators which parallels similar developments in North America and elsewhere. Most recently, this has increased because major European Union Directives require that indicators of marine benthic change are used to confirm good ecological status quality (as in the Water Framework Directive) and favourable conservation status (as in the Habitats and Species Directive). Furthermore, these indicators have to fit within the current philosophy of the Ecosystem Approach requiring the development and use of Ecological Quality Objectives and Standards. Despite this, comparisons of families of indicators derived by differing methods have not been carried out such that the robust nature of the indicators on differing spatial scales and under differing benthic conditions has not been rigorously assessed. Using case studies from the Portuguese coasts and estuaries, this paper compares and contrasts univariate and multivariate macrobenthic indicators to quantify comparisons of change. The studies indicate the relative value of those indicators at contrasting spatial scales, e.g. in the transition from small areas around coastal submarine outfalls, to the local and regional estuarine and coastal scale. The analysis indicates the difficulties of deriving and using qualitative and quantitative indicators from benthic communities in stable, and in moderately and highly variable environmental conditions in estuarine, coastal and open sea habitats. In some areas, the variability in the indicators and indices within a station and site is as large as that between stations and sites. For those areas studied, there is an adequate quality and quantity of benthic data available for making management decisions but this is unlikely to be the case for all areas. Similarly, the interrogation of the methods shows that while their use and interpretation rely on a good understanding of the biology of the individual species and their responses to physical and polluting stress, that understanding is not yet available for many of the species. Most notably, while the indices and integrative indicators are becoming increasingly sophisticated, many are still dependent on the Pearson-Rosenberg model for organic enrichment hence they require to be validated for physical disturbance and for chemical pollution. Because of these features, the outcome of the analysis has repercussions for the management of coastal and estuarine areas. Although the present study indicates the value of indicators of benthic change for making management decisions at the various scales, further validation is required especially, for example, where one indicator over-estimates the ecological status for poor areas and underestimates it for good areas.     

Benthic Diatom Communities Along pH and TP Gradients in Hungarian and Swedish Streams

Benthic diatoms are widely used in Europe to assess ecological status of running waters. The aim of this study was to develop models to predict average pH and total phosphorus (TP) for European stream monitoring using combined diatom data-sets from Hungary and Sweden. As first step, the relationship between the measured environmental variables and the distribution of the taxa was checked by classification by using cluster-analysis and CCA. Diatom data separated clearly along the main hydrogeochemical parameters (e.g. alkalinity, pH). Concerning nutrients, TP was the most determinant factor. Predictive value of the TP model (r = 0.96) is high only for the Hungarian data and the pH model (r = 0.97) can be used in both phycogeographical regions.     

Structural Alterations within Native Amyloidogenic Immunoglobulin Light Chains

Amyloid diseases are characterized by the misfolding of a precursor protein that leads to amyloid fibril formation. Despite the fact that there are different precursors, some commonalities in the misfolding mechanism are thought to exist. In light chain amyloidosis (AL), the immunoglobulin light chain forms amyloid fibrils that deposit in the extracellular space of vital organs. AL proteins are thermodynamically destabilized compared to non-amyloidogenic proteins and some studies have linked this instability to increased fibril formation rates. Here we present the crystal structures of two highly homologous AL proteins, AL-12 and AL-103. This structural study shows that these proteins retain the canonical germ line dimer interface. We highlight important structural alterations in two loops flanking the dimer interface and correlate these results with the somatic mutations present in AL-12 and AL-103. We suggest that these alterations are informative structural features that are likely contributing to protein instability that leads to conformational changes involved in the initial events of amyloid formation.     

Word learning,phonological short-term memory,phonotactic probability and long-term memory: towards an integrated framework

Word learning is studied in a multitude of ways, and it is often not clear what the relationship is between different phenomena. In this article, we begin by outlining a very simple functional framework that despite its simplicity can serve as a useful organizing scheme for thinking about various types of studies of word learning. We then review a number of themes that in recent years have emerged as important topics in the study of word learning, and relate them to the functional framework, noting nevertheless that these topics have tended to be somewhat separate areas of study. In the third part of the article, we describe a recent computational model and discuss how it offers a framework that can integrate and relate these various topics in word learning to each other. We conclude that issues that have typically been studied as separate topics can perhaps more fruitfully be thought of as closely integrated, with the present framework offering several suggestions about the nature of such integration.     

Hydrothermal synthesis, structure and rare ferromagnetic property of a 3-D Nd(III) metal-organic framework based on mixed pyridine-2,5-dicarboxylic acid/nicotinic acid ligands

A novel 3-D metal-organic framework Nd(2,5-pydc)(nic)(H₂O) (1, 2,5-pydc = pyridine-2,5-dicarboxylic acid, nic = nicotinic acid) has been hydrothermally synthesized and characterized by elemental analyses, IR, and X-ray single-crystal diffraction. Compound 1 is the first MOF based on mixed 2,5-pydc/nic ligands. The title compound displays an interseting 3-D (6,3)-connected network with the topology of (4.6²)₂(4² × 6¹⁰ × 8³). Magnetic susceptibility measurements show that compound1 presents a rare ferromagnetic interaction between two adjacent Nd(III) ions.     

Synthesis and characterization of a novel photoluminescent three-dimensional metal-organic framework

A novel metal-organic framework containing one-dimensional channels of formula [Zn₃(Aco)₂(H₂O)₆]_n (H₃Aco = aconitic acid) has been synthesized and characterized by FT-IR spectroscopy, thermogravimetric analysis (TG), X-ray analysis, and solid state photoluminescence spectra. X-ray crystallographic studies reveal that there are two kinds of crystallographically independent Zn atoms in the title complex. The most interesting feature of the structure is an unprecedented 3D MOF containing infinite Zn(1) linear chains and heterochiral Zn(2) single-stranded helices. The linear chains and helices happen to be perpendicular to each other. Photoluminescence properties of the title compound have been examined in the solid state at room temperature.     

Synthesis of copper-zinc bimetallic imidazolate framework compounds and the structure of Cu(I)-containing Cu2Zn(N2C3H3)4

Copper(II)-zinc(II) bimetallic imidazolate metal-organic framework compounds of composition Cu_aZn_bIm_2(a + b) (Im = C₃H₃N₂), including Cu₂ZnIm₆ (1), were prepared in high yields from the metal oxides under mild aqueous conditions using a novel acid catalysis method. Mild acidic hydrothermal treatment of paramagnetic 1 (≥120 °C) gave diamagnetic Cu(I)-containing Cu₂ZnIm₄ (2) in high yield. The formation mechanism of 2 involves electron transfer from Im⁻ to Cu(II), with concomitant formation of the unusual cyclotriimidazole, C₉H₆N₆. Air-stable 2, characterized by single-crystal X-ray diffraction, crystallized in the tetragonal space group , with a = b = 10.9623(3), c = 6.3231(4) Å, α = β = γ = 90°, V = 759.86(6) Å³, and Z = 1.