462 research outputs found

    Energianvändning och livscykelkostnad för ventilations- och uppvärmningssystem i småhus

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    Agroclimatic conditions in Europe under climate change

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    o date, projections of European crop yields under climate change have been based almost entirely on the outputs of crop-growth models. While this strategy can provide good estimates of the effects of climatic factors, soil conditions and management on crop yield, these models usually do not capture all of the important aspects related to crop management, or the relevant environmental factors. Moreover, crop-simulation studies often have severe limitations with respect to the number of crops covered or the spatial extent. The present study, based on agroclimatic indices, provides a general picture of agroclimatic conditions in western and central Europe (study area lays between 8.5°W–27°E and 37–63.5°N), which allows for a more general assessment of climate-change impacts. The results obtained from the analysis of data from 86 different sites were clustered according to an environmental stratification of Europe. The analysis was carried for the baseline (1971–2000) and future climate conditions (time horizons of 2030, 2050 and with a global temperature increase of 5 °C) based on outputs of three global circulation models. For many environmental zones, there were clear signs of deteriorating agroclimatic condition in terms of increased drought stress and shortening of the active growing season, which in some regions become increasingly squeezed between a cold winter and a hot summer. For most zones the projections show a marked need for adaptive measures to either increase soil water availability or drought resistance of crops. This study concludes that rainfed agriculture is likely to face more climate-related risks, although the analyzed agroclimatic indicators will probably remain at a level that should permit rainfed production. However, results suggests that there is a risk of increasing number of extremely unfavorable years in many climate zones, which might result in higher interannual yield variability and constitute a challenge for proper crop management

    Climate change and agricultural land use in Sweden

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    The purpose of this literature review is to create a base of information to identify gaps of knowledge in the assessment of the effects of climate change on agriculture in Sweden, and related effects of agricultural adaptation and mitigation measures. The review is a part of a project (FANAN, Fogelfors et al. 2008) at the Swedish University of Agricultural Sciences aiming at making a strategic analysis of future research needs for agriculture in Sweden, and should help in answering the following questions: What are the expected impacts of climate change on agricultural production and its effects on environment, which are the suggested methods for mitigation and adaptation, and what is the scientific base on which these assessments stands? The work has been done in the following way: Literature has basically been searched for on the “Web of Science”. The review has focused on scientific literature, although the literature has also been searched on the whole “Web”, and several references have been found elsewhere in a non-systematic way. The limited number of researchers involved and time available for the study allowed only a few topics to be thoroughly examined. References within many topics are though cited, but the list is incomplete. Thus the reference list should not be regarded to be complete. Mainly abstracts have been read and analysed for results, conclusions and methods. The text has basically the character of citations using expressions close to those of the authors of the articles, although our own analyses were now and then unavoidable. All evaluations by us, the authors of this report, are intended to be concentrated to the summary. The citations are structured in relation to the questions they give answers to. The reader is recommended to use the questions to find the information of her/his interest. The study was financed by the Faculty of Natural Resources and Agricultural Science at the Swedish University of Agricultural Sciences and the authors would like to thank colleagues at the Departments for Crop Production Ecology, Economy, Animal Nutrition and Management, and Soil and Environment for contributions and kind help

    Amino Aacohols : stereoselective synthesis and applications in diversity-oriented synthesis

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    This thesis is divided into three separate parts with amino alcohols as the common feature. The first part describes the development of a novel three-component approach to the synthesis of α-hydroxy-β-amino esters. Utilizing a highly diastereoselective Rh(II)-catalyzed 1,3-dipolar cycloaddition of carbonyl ylides to various aldimines, syn-α-hydroxy-β-amino esters formed in high yields and excellent diastereoselectivities. This methodology was also applied in a short enantioselective synthesis of the C-13 side-chain of Taxol. The second part of the thesis describes a total synthesis of D-erythro- Sphingosine based on a cross-metathesis approach to assemble the polar head group and the aliphatic chain. The last part deals with the application of amino alcohols as scaffolds in a diversity-oriented protocol for the development of libraries of small polycyclic molecules. The design of the libraries is based on the iterative use of two powerful ring-forming reactions; a ring-closing metathesis and an intramolecular Diels-Alder reaction, to simultaneously introduce structural complexity and diversity.QC 2010122

    Total Synthesis of (-)-Stemoamide (I).

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    Stereoselective Synthesis of Amino Alcohols : Applications to Natural Product Synthesis

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    This thesis is divided into four separate parts with amino alcohols as the common feature. The first part of the thesis describes the development of an efficient three-component approach to the synthesis of α-hydroxy-β-amino esters. Utilizing a highly diastereoselective Rh(II)-catalyzed 1,3-dipolar cycloaddition of carbonyl ylides to various aldimines, syn-α-hydroxy-β-amino esters are formed in high yields and excellent diastereoselectivities. An asymmetric version was also developed by employing chiral α-methylbenzyl imines as dipolarophiles yielding enantiomerically pure syn-α-hydroxy-β-amino esters. This methodology was also applied on a short asymmetric synthesis of the paclitaxel side-chain as well as in an asymmetric synthetic approach towards the proteasome inhibitor omuralide. Furthermore, the use of chiral Rh(II) carboxylates furnishes the syn-α-hydroxy-β-amino esters in moderate enantioselectivity (er up to 82:18), which indicates that the reaction proceeds via a metal-associated carbonyl ylide. The second part describes the development of a 1,3-dipolar cycloaddition reaction of azomethine ylides to aldehydes for the synthesis of α-amino-β-hydroxy esters. Different methods for the generation of the ylides, including Vedejs’ oxazole methology and an Ag(I)/phosphine-catalyzed approach have been evaluated. The best results were obtained with the Ag(I)/phosphine approach, which yielded the desired α-amino-β-hydroxy ester in 68% yield and 3.4:1 syn:anti-selectivity. The last two parts deals with the total synthesis of the amino alcohol-containing natural products D-erythro-sphingosine and (−)-stemoamide. The key transformation in the sphingosine synthesis is a cross-metathesis reaction for the assembly of the polar head group and the aliphatic chain. In the stemoamide synthesis, the key feature is an iodoboration/Negishi/RCM-sequence for the construction of the β,γ-unsaturated azepine core of stemoamide followed by a stereoselective bromolactonization/1,4-reduction strategy for the installation of the requisite C8-C9 trans-stereochemistry.QC 2010082
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