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1.
Keith W.T.Goulding 《中国科学:生命科学英文版》2005,48(Z2)
The nitrogen (N) cycle is essentially 'leaky'. The losses of small amounts of nitrate to waters and of ammonia and nitrous oxide to the atmosphere are a part of the global biogeo-chemical N cycle. However, intensive agricultural production, industry and vehicle use have more than doubled the amount of 'reactive' N in the environment, resulting in eutrophication, ecosystem change and health concerns. Research has identified agricultural practices that cause large losses of N and, in some cases, developed solutions. This paper discusses the problems of maintaining productivity while reducing N losses, compares conventional with low input (integrated) and organic farming systems, and discusses wider options. It also looks at the need to integrate studies on N with other environmental impacts, set in the context of the whole farm system, to provide truly sustainable agricultural systems. 相似文献
2.
Marie Helleberg Bamenla Q Goka Bartholomew D Akanmori George Obeng-Adjei Onike Rodriques Jorgen AL Kurtzhals 《Malaria journal》2005,4(1):1-7
In sub-Saharan Africa the highest overlap between malaria and HIV infections occurs in female adolescents. Yet control activities for these infections are directed to different target groups, using disparate channels. This reflects the lack of priority given to adolescents and the absence of an accepted framework for delivering health and health-related interventions to this high-risk group. In this paper it is argued that female adolescents require a continuum of care for malaria and HIV – prior to conception, during and after pregnancy and that this should be provided through adolescent services. The evidence for this conclusion is presented. A number of African countries are commencing to formulate and implement adolescent-friendly policies and services and disease control programs for malaria and HIV will need to locate their interventions within such programs to ensure widespread coverage of this important target group. Failure to prioritize adolescent health in this way will seriously limit the success of disease control programs for malaria and HIV prevention. 相似文献
3.
Anthony Verdin Anissa Louns-Hadj Sahraoui Frdric Laruelle Anne Grandmougin-Ferjani Roger Durand 《Mycological Research》2006,110(4):479-484
The purpose of the present paper was to study the effect of the high polycyclic aromatic hydrocarbon (PAH), benzo[a]pyrene, on the lipid [fatty acid (FA) and sterol] composition and content of the fungi Fusarium solani and F. oxysporum, respectively recognized as good and poor PAH degraders. The major FAs and the major sterol that characterized the tested Fusarium strains were C16:0, C18:1, C18:2, and ergosterol. Lipid profiles of F. solani remained unchanged with the addition of benzo[a]pyrene in the culture media at all concentrations and duration of treatment. However, in the presence of benzo[a]pyrene, significant decreases in FA content, which reached 18 % in young cultures and 28 % in mature colonies, were registered. Similarly, the sterol content of F. solani was reduced by 27 % in the presence of benzo[a]pyrene. In contrast, no modification in lipid profile and lipid content were observed with F. oxysporum, a strain recognized as a low benzo[a]pyrene degrader. 相似文献
4.
ERIC S. BONO PATRICK SMOLINSKI AL CASAGRANDA JUNDE XU 《Computer methods in biomechanics and biomedical engineering》2013,16(2):125-131
The Shear-slip Mesh Update Method (SSMUM) is being used in flow simulations involving large but regular displacements of one or more boundaries of the computational domain. We follow up the earlier discussion of the method with notes on practical implementation aspects. In order to establish a benchmark problem for this class of flow problems, we define and report results from a two-dimensional viscous flow around a rotating stirrer in a square chamber. The application potential of the method is demonstrated in the context of biomedical design problem, as we perform an analysis of blood flow in a centrifugal left ventricular assist device, or blood pump, which involves a rotating impeller in a non-axisymmetric housing. 相似文献
5.
6.
Angela Karp Steve J.Hanley Sviatlana O.Trybush William Macalpine Ian Shield 《Acta Botanica Sinica》2011,(2)
Willows (Salix spp.) are a very diverse group of catkin-bearing trees and shrubs that are widely distributed across temperate regions of the globe.Some species respond well to being grown in short rotation coppice (SRC) cycles,which are much shorter than conventional forestry.Coppicing reinvigorates growth and the biomass rapidly accumulated can be used as a source of renewable carbon for bioenergy and biofuels.As SRC willows re-distribute nutrients during the perennial cycle they require only minimal nitro... 相似文献
7.
HENRY SILVERMAN BABIKER AHMED SAMAR AJEILET SUMAIA AL‐FADIL SUHAIL AL‐AMAD HADIR EL‐DESSOUKY IBRAHIM EL‐GENDY MOHAMED EL‐GUINDI MUSTAFA EL‐NIMEIRI RANA MUZAFFAR AZZA SALEH 《Developing world bioethics》2010,10(2):70-77
To help ensure the ethical conduct of research, many have recommended educational efforts in research ethics to investigators and members of research ethics committees (RECs). One type of education activity involves multi‐day workshops in research ethics. To be effective, such workshops should contain the appropriate content and teaching techniques geared towards the learning styles of the targeted audiences. To ensure consistency in content and quality, we describe the development of a curriculum guide, core competencies and associated learning objectives and activities to help educators organize research ethics workshops in their respective institutions. The curriculum guide is divided into modular units to enable planners to develop workshops of different lengths and choose content materials that match the needs, abilities, and prior experiences of the target audiences. The content material in the curriculum guide is relevant for audiences in the Middle East, because individuals from the Middle East who participated in a Certificate Program in research ethics selected and developed the training materials (e.g., articles, powerpoint slides, case studies, protocols). Also, many of the activities incorporate active‐learning methods, consisting of group work activities analyzing case studies and reviewing protocols. The development of such a workshop training curriculum guide represents a sustainable educational resource to enhance research ethics capacity in the Middle East. 相似文献
8.
The energy produced from the investment in biofuel crops needs to account for the environmental impacts on soil, water, climate change and ecosystem services. A regionalized approach is needed to evaluate the environmental costs of large-scale biofuel production. We present a regional pan-European simulation of rapeseed ( Brassica napus ) cultivation. Rapeseed is the European Union's dominant biofuel crop with a share of about 80% of the feedstock. To improve the assessment of the environmental impact of this biodiesel production, we performed a pan-European simulation of rapeseed cultivation at a 10 × 10 km scale with Environmental Policy Integrated Climate (EPIC). The model runs with a daily time step and model input consists of spatialized meteorological measurements, and topographic, soil, land use, and farm management practices data and information. Default EPIC model parameters were calibrated based on literature. Modelled rapeseed yields were satisfactory compared with yields at regional level reported for 151 regions obtained for the period from 1995 to 2003 for 27 European Union member countries, along with consistent modelled and reported yield responses to precipitation, radiation and vapour pressure deficit at regional level. The model is currently set up so that plant nutrient stress is not occurring. Total fertilizer consumption at country level was compared with IFA/FAO data. This approach allows us to evaluate environmental pressures and efficiencies arising from and associated with rapeseed cultivation to further complete the environmental balance of biofuel production and consumption. 相似文献
9.
Carlos García-Estrada Inmaculada Vaca Ricardo V Ullán Marco A van den Berg Roel AL Bovenberg Juan Francisco Martín 《BMC microbiology》2009,9(1):104-15
Background
Penicillium chrysogenum converts isopenicillin N (IPN) into hydrophobic penicillins by means of the peroxisomal IPN acyltransferase (IAT), which is encoded by the penDE gene. In silico analysis of the P. chrysogenum genome revealed the presence of a gene, Pc13g09140, initially described as paralogue of the IAT-encoding penDE gene. We have termed this gene ial because it encodes a protein with high similarity to IAT (IAL for IAT-Like). We have conducted an investigation to characterize the ial gene and to determine the role of the IAL protein in the penicillin biosynthetic pathway. 相似文献10.
ZHENZHEN YI WEIBO SONG THORSTEN STOECK KHALED A. S. AL‐RASHEID ABDULAZIZ A. AL‐KHEDHAIRY JUN GONG HONGWEI MA ZIGUI CHEN 《Zoological Journal of the Linnean Society》2009,157(2):227-236
The morphologically unique ciliate Psammomitra has long been considered as a systematically uncertain stichotrich. This is mainly because of its highly specialized morphology and a lack of either detailed information concerning its ontogenesis, or molecular data. Based on the small subunit rRNA (SSrRNA) gene and alpha‐tubulin gene sequences, we re‐evaluated the phylogenetic position of Psammomitra retractilis using multiple algorithms. Phylogenetic trees inferred from the SSrRNA gene sequences representing a total of 53 spirotrichs demonstrated the closest relationship of Psammomitra was with Holosticha‐like taxa, with strong support, which clearly suggested that Psammomitra should be placed into the order Urostylida although it branched at a rather deep level, and is likely to be closely related to Holostichidae. With consideration to molecular evidence and morphological characters, Psammomitra should be a clearly outlined taxon at about the rank of family, i.e. Psammomitridae stat. nov. , within the order Urostylida. The improved diagnosis for this family is as follows: Urostylida possessing extremely contractile, elongated body which consists of three parts: head, trunk, and slender tail; midventral complex composed of midventral pairs only and restricted to about anterior 1/3 of ventral surface; frontal, frontoterminal, and transverse cirri present; one left and one right marginal rows which commence near proximal end of adoral zone and extend to near rear body end. 相似文献