Rice field flora and vegetation in the provinces of Valencia and Tarragona

Twenty nine emergent and twenty floating or submerged taxa , were found in the rice fields in Valencia and Tarragona provinces. Eleven of the se taxa, all them emergent, are alien Of introduced ones. Echinochloa oryzoides and E. oryzicola are the most important in both areas, together with Cyperus difformis and Echinochloa hispidula in Valencia. The remaining thirty eight taxa belong to the native flora. There are predominantly the emergent Scirpus maritimus, Alisma plantago-aquatica. Echinochloa crus-galli and Paspalum distichum; the floating Lemna minor and L. gibba; the submersed Potamogeton nodosus; Zannichellia palustris and Najas minor; and the macroscopical algae Chara vulgaris, Cladophora glomerata, Oedogonium capilliforme, Spirogyra spp., Pithophora oedogania and Hydrodictyon reticulatum. The flora evolution during the last years is analyzed and the present weed communities are studied. The contribution of the different phytosociological classes to the rice field weed flora is presented.De los 49 táxones registrados (29 emergentes y 20 flotantes o sumergidos) 11 son exóticos introducidos, de los cuales los más importantes son Echinochloa oryzoides y E. oryzicolaen ambas zonas, además de Cyperus difformis y Echinochloa hispidula en Valencia, y el resto propios de la flora autóctona, predominando Scirpus maritimus, Alisma plantago-aquatica. Echinochloa crus-galli y Paspalum distichum como emergentes, Lemna minor y L. gibba como flotantes, Potamogeton nodosus, Zannichellia palustris y Najas minor como sumergidos y Chara vulgaris, Cladophora glomerata, Oedogonium capilliforme. Spirogyra spp., Pirhophora oedogonia e Hydrodictyon reticulatum como algas macroscópicas. Se analiza la evolución experimentada por la flora en los últimos años, además de estudiar las comunidades vegetales presentes y de indicar la importancia de las distintas clases fitosociológicas en su contribución a la flora arvense del cultivo

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A robust test for serial correlation in panel data models

We consider a new nonparametric test for serial correlation of unknown form in the estimated residuals of a panel regression model, where individual and time effects can be fixed or random, and the panel data can be balanced or unbalanced. Our test is robust against potential weak error cross-sectional dependence and error serial dependence in higher-order moments. This is in contrast to existing tests for serial correlation in panel data models, which assume error components to be cross-sectionally and serially independent. Our test has an asymptotic N(0, 1) distribution under the null hypothesis and is consistent against serial correlation of unknown form. No common alternative is assumed and hence our test allows for substantial inhomogeneity in serial correlation across individuals. A simulation study highlights the merits of the proposed test relative to a variety of existing tests in the literature. We apply the new test to the empirical study of Wolfers on the relationship between unilateral divorce laws and divorce rates and find strong evidence against serial uncorrelatedness even controlling for the fixed effect.</p

Network Environ Perspective for Urban Metabolism and Carbon Emissions: A Case Study of Vienna, Austria

Cities are considered major contributors to global warming, where carbon emissions are highly embedded in the overall urban metabolism. To examine urban metabolic processes and emission trajectories we developed a carbon flux model based on Network Environ Analysis (NEA). The mutual interactions and control situation within the urban ecosystem of Vienna were examined, and the system-level properties of the city’s carbon metabolism were assessed. Regulatory strategies to minimize carbon emissions were identified through the tracking of the possible pathways that affect these emission trajectories. Our findings suggest that indirect flows have a strong bearing on the mutual and control relationships between urban sectors. The metabolism of a city is considered self-mutualistic and sustainable only when the local and distal environments are embraced. Energy production and construction were found to be two factors with a major impact on carbon emissions, and whose regulation is only effective via ad-hoc pathways. In comparison with the original life-cycle tracking, the application of NEA was better at revealing details from a mechanistic aspect, which is crucial for informed sustainable urban management

Tracking Inter-Regional Carbon Flows: A Hybrid Network Model

The mitigation of anthropogenic carbon emissions has moved beyond the local scale because they diffuse across boundaries, and the consumption that triggers emissions has become regional and global. A precondition of effective mitigation is to explicitly assess inter-regional transfer of emissions. This study presents a hybrid network model to track inter-regional carbon flows by combining network analysis and input–output analysis. The direct, embodied, and controlled emissions associated with regions are quantified for assessing various types of carbon flow. The network-oriented metrics called “controlled emissions” is proposed to cover the amount of carbon emissions that can be mitigated within a region by adjusting its consumption. The case study of the Jing–Jin–Ji Area suggests that CO₂ emissions embodied in products are only partially controlled by a region from a network perspective. Controlled carbon accounted for about 70% of the total embodied carbon flows, while household consumption only controlled about 25% of Beijing’s emissions, much lower than its proportion of total embodied carbon. In addition to quantifying emissions, the model can pinpoint the dominant processes and sectors of emissions transfer across regions. This technique is promising for searching efficient pathways of coordinated emissions control across various regions connected by trade

Driving Force Analysis of the Agricultural Water Footprint in China Based on the LMDI Method

China’s water scarcity problems have become more severe because of the unprecedented economic development and population explosion. Considering agriculture’s large share of water consumption, obtaining a clear understanding of Chinese agricultural consumptive water use plays a key role in addressing China’s water resource stress and providing appropriate water mitigation policies. We account for the Chinese agricultural water footprint from 1990 to 2009 based on bottom up approach. Then, the underlying driving forces are decomposed into diet structure effect, efficiency effect, economic activity effect, and population effect, and analyzed by applying a log-mean Divisia index (LMDI) model. The results reveal that the Chinese agricultural water footprint has risen from the 94.1 Gm³ in 1990 to 141 Gm³ in 2009. The economic activity effect is the largest positive contributor to promoting the water footprint growth, followed by the population effect and diet structure effect. Although water efficiency improvement as a significant negative effect has reduced overall water footprint, the water footprint decline from water efficiency improvement cannot compensate for the huge increase from the three positive driving factors. The combination of water efficiency improvement and dietary structure adjustment is the most effective approach for controlling the Chinese agricultural water footprint’s further growth

Thermal and Catalyzed [3,3]-Phosphorimidate Rearrangements

[3,3]-Sigmatropic rearrangements have been widely utilized for the synthesis of structurally complex organic molecules because of the ease with which carbon−carbon bonds are formed in a regio- and stereocontrolled manner. However, there are far fewer [3,3]-rearrangements available for the selective formation of carbon−nitrogen bonds despite the enormous potential of such reactions for the preparation of stereodefined allylic amines. We describe here the scope and mechanism of a [3,3]-rearrangement of allylic phosphorimidates that provides access to stereodefined allylic amines of diverse structure. The reactive intermediate in the reaction, an allylic phosphorimidate, is produced in situ through the combination of readily available starting materials (allylic alcohols, chlorophosphites, and organic azides), rendering the reaction an efficient three-component process. Analogous to other [3,3]-rearrangements, the stereochemistry in an allylic alcohol starting material is transferred with fidelity to the allylic amine product and, further, allylic amines are produced as single olefin isomers. In addition, a crossover experiment indicates that the rearrangement is an intramolecular process. Finally, activation of the allylic moiety either through incorporation of electron-deficient functional groups or through the use of a transition-metal catalyst significantly facilitates the reaction and consequently the preparation of a wider range of substitution patterns

White-Light-Emitting Polymer Composite Film Based on Carbon Dots and Lanthanide Complexes

A white-light-emitting polymer composite film was designed and synthesized by using carbon dots (CDs) and lanthanide complexes as primary light emitters and skillfully embedding them into a poly­(methyl methacrylate) (PMMA) matrix. The hydrophilic CDs used as blue light source were prepared and functionalized by copolymerizing with methacrylate to prevent their aggregate in the hydrophobic matrix. The lanthanide complexes Eu­(DBM)₃ and Tb­(DBM)₃ (DBM: dibenzoylmethide), in which the rare earth ions have not been fully coordinated, were fabricated and used as red and green emitters. The coordinatively unsaturated lanthanide ions could further coordinate with the oxygen atoms in the PMMA chains, which makes the complexes homogeneously dispersed in matrix as well as benefits to the energy transfer process. By adjusting the ratio of CDs, Eu­(DBM)₃ and Tb­(DBM)₃ in the matrix, the high transparent film with improved thermal stability, which prepared by a simple solution cast method, could emit pure white light (CIE coordinate located at (0.31, 0.32)) under 400 nm laser with a quantum efficiency of 16.6%. The energy transfer mechanism in the white-light-emitting material was also discussed

Ecological Network Analysis for a Virtual Water Network

The notions of virtual water flows provide important indicators to manifest the water consumption and allocation between different sectors via product transactions. However, the configuration of virtual water network (VWN) still needs further investigation to identify the water interdependency among different sectors as well as the network efficiency and stability in a socio-economic system. Ecological network analysis is chosen as a useful tool to examine the structure and function of VWN and the interactions among its sectors. A balance analysis of efficiency and redundancy is also conducted to describe the robustness (<i>R</i>_VWN) of VWN. Then, network control analysis and network utility analysis are performed to investigate the dominant sectors and pathways for virtual water circulation and the mutual relationships between pairwise sectors. A case study of the Heihe River Basin in China shows that the balance between efficiency and redundancy is situated on the left side of the robustness curve with less efficiency and higher redundancy. The forestation, herding and fishing sectors and industrial sectors are found to be the main controllers. The network tends to be more mutualistic and synergic, though some competitive relationships that weaken the virtual water circulation still exist

A Phosphorimidate Rearrangement for the Facile and Selective Preparation of Allylic Amines

Allylic phosphorimidates, readily prepared from the combination of an allylic alcohol, an azide, and a chlorophosphite, undergo [3,3]-rearrangement under thermal conditions to provide single isomers of allylic phosphoramidates. This new rearrangement is tolerant of a range of substitution patterns on the reactants. Treatment of the products of the rearrangement with ethanethiolate followed by acid produces a protected allylic amine. This strategy thus provides an attractive and versatile procedure for the preparation of key synthetic intermediates, allylic amines