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231.
232.
Joyce Cooper Christina Godwin Edie Sonne Hall 《The International Journal of Life Cycle Assessment》2008,13(2):115-123
Background, Aims and Scope Although LCA is frequently used in product comparison, many practitioners are interested in identifying and assessing improvements
within a life cycle. Thus, the goals of this work are to provide guidelines for scenario formulation for process and material alternatives
within a life cycle inventory and to evaluate the usefulness of decision tree and matrix computational structures in the assessment
of material and process alternatives. We assume that if the analysis goal is to guide the selection among alternatives towards
reduced life cycle environmental impacts, then the analysis should estimate the inventory results in a manner that: (1) reveals
the optimal set of processes with respect to minimization of each impact of interest, and (2) minimizes and organizes computational
and data collection needs.
Methods A sample industrial system is used to reveal the complexities of scenario formulation for process and material alternatives
in an LCI. The system includes 4 processes, each executable in 2 different ways, as well as 1 process able to use 2 different
materials interchangeably. We formulate and evaluate scenarios for this system using three different methods and find advantages
and disadvantages with each. First, the single branch decision tree method stays true to the typical construction of decision
trees such that each branch of the tree represents a single scenario. Next, the process flow decision tree method strays from
the typical construction of decision trees by following the process flow of the product system, such that multiple branches
are needed to represent a single scenario. In the final method, disaggregating the demand vector, each scenario is represented
by separate vectors which are combined into a matrix to allow the simultaneous solution of the inventory problem for all scenarios.
Results For both decision tree and matrix methods, scenario formulation, data collection, and scenario analysis are facilitated in
two ways. First, process alternatives that cannot actually be chosen should be modeled as sub-inventories (or as a complete
LCI within an LCI). Second, material alternatives (e.g., a choice between structural materials) must be maintained within
the analysis to avoid the creation of artificial multi-functional processes. Further, in the same manner that decision trees
can be used to estimate ‘expected value’ (the sum of the probability of each scenario multiplied by its ‘value’), we find
that expected inventory and impact results can be defined for both decision tree and matrix methods.
Discussion For scenario formulation, naming scenarios in a way that differentiate them from other scenarios is complex and important
in the continuing development of LCI data for use in databases or LCA software. In the formulation and assessment of scenarios,
decision tree methods offer some level of visual appeal and the potential for using commercially available software/ traditional
decision tree solution constructs for estimating expected values (for relatively small or highly aggregated product systems).
However, solving decision tree systems requires the use of sequential process scaling which is difficult to formalize with
mathematical notation. In contrast, preparation of a demand matrix does not require use of the sequential method to solve
the inventory problem but requires careful scenario tracking efforts.
Conclusions Here, we recognize that improvements can be made within a product system. This recognition supports the greater use of LCA
in supply chain formation and product research, development, and design. We further conclude that although both decision tree
and matrix methods are formulated herein to reveal optimal life cycle scenarios, the use of demand matrices is preferred in
the preparation of a formal mathematical construct. Further, for both methods, data collection and assessment are facilitated
by the use of sub-inventories (or as a complete LCI within an LCI) for process alternatives and the full consideration of
material alternatives to avoid the creation of artificial multi-functional processes.
Recommendations and Perspectives The methods described here are used in the assessment of forest management alternatives and are being further developed to
form national commodity models considering technology alternatives, national production mixes and imports, and point-to-point
transportation models.
ESS-Submission Editor: Thomas Gloria, PhD (t.gloria@fivewinds.com) 相似文献
233.
234.
Eugene Diatloff Emma S. Mace David R. Jordan Sophie Filleur Shuaishuai Tai Susanne Schmidt Ian D. Godwin 《Molecular breeding : new strategies in plant improvement》2017,37(11):138
Improving the nitrogen (N) responsiveness of crops is crucial for food security and environmental sustainability, and breeding N use efficient (NUE) crops has to exploit genetic variation for this complex trait. We used reverse genetics to examine allelic variation in two N metabolism genes. In silico analysis of the genomes of 44 genetically diverse sorghum genotypes identified a nitrate reductase and a glutamate synthase gene that were under balancing selection in improved sorghum cultivars. We hypothesised that these genes are a potential source of differences in NUE, and selected parents and progeny of nested association mapping populations with different allelic combinations for these genes. Allelic variation was sourced from African (Macia) and Indian (ICSV754) genotypes that had been incorporated into the Australian elite parent R931945-2-2. Nine genotypes were grown for 30 days in a glasshouse and supplied with continuous limiting or replete N, or replete N for 27 days followed by 3 days of N starvation. Biomass, total N and nitrate contents were quantified together with gene expressions in leaves, stems and roots. Limiting N supply universally resulted in less shoot and root growth, increased root weight ratio and reduced tissue nitrate and total N concentrations. None of the tested genotypes exceeded growth or NUE of the elite parent R931945-2-2 indicating that the allelic combinations did not confer an advantage during early vegetative growth. Thus, the next steps for ascertaining potential effects on NUE include growing plants to maturity. We conclude that reverse genetics that take advantage of rapidly expanding genomic databases enable a systematic approach for developing N-efficient crops. 相似文献
235.
I. D. Godwin N. Sangduen R. Kunanuvatchaidach G. Piperidis S. W. Adkins 《Plant cell reports》1997,16(5):320-324
Summary RAPD analysis was performed among eight rice somaclonal families known to vary for specific characters and four somaclonal families which were phenotypically normal. The parental cultivar,indica rice cv. FR13A, was found to be homogeneous and homozygous at all but one of the 45 RAPD loci. Polymorphisms were found at 28 of the 45 bands among the somaclonal families, including both loss of parental bands, and the appearance of novel non-parental bands. Segregation data revealed both heterozygous and homozygous mutation events, with recessive mutations more prevalent than dominant. All somaclonal families differed significantly from the parental material, indicating that genomic alterations occurred in all families regardless of phenotype. None of the variant families could be regarded as isogenic lines of FR13A at the DNA level. However, some of the DNA level variation may be in highly repeated sequences with no phenotypic effects. The implications for somaclonal breeding and genetic engineering programs are discussed. 相似文献
236.
OBJECTIVES--To describe the organisms cultured from general practitioners'' auriscope earpieces; and to explore general practitioners'' perceptions of the possibility of cross infection from contaminated auriscope earpieces and of how their auriscope earpieces are cleaned. DESIGN--Microbiological survey of auriscope earpieces in two general practices and a semistructured questionnaire sent to 105 general practitioners. SETTING--General practitioners served by one district general hospital microbiology laboratory in the north of England. RESULTS--Organisms were cultured from 41 (93%) of 44 auriscope earpieces, of which 14 (32%) carried potential pathogens; four (9%) were heavily contaminated. Of the 85 (81%) general practitioners who responded, 72 (85%) believed that contaminated auriscope earpieces could cause serious infection, 66 (78%) did not clean earpieces between patients, and 70 (82%) thought that patients would mind if they knew that dirty earpieces were used. CONCLUSIONS--Almost a third of auriscope earpieces were contaminated by pathogenic bacteria. Although general practitioners suspected this, most did not ensure that a clean earpiece was used for each patient. 相似文献
237.
Godwin Böckel 《Plant Systematics and Evolution》1864,14(4):117-119
Ohne Zusammenfassung 相似文献
238.
N S Agar I R Godwin M Suzuki J Hablethwaite J Roberts I D Hume 《Comparative biochemistry and physiology. A, Comparative physiology》1986,85(2):297-299
Aspects of red blood cell metabolism were compared among three species of small macropodid marsupials from different habitats. Packed cell volume (PCV), erythrocyte reduced glutathione (GSH) concentration and GSH regeneration rates were similar in all three species. The Parma wallaby had very low red cell potassium levels compared to the other species studied. The Tammar wallaby had higher rates of glucose consumption and lactate production in vitro at both pH 7.4 and 8.2 than did the Parma and significantly lower adenosine triphosphate (ATP) levels than the other species. These findings are consistent with preliminary reports published previously. The differences noted cannot be directly related to differences in the habitats of the species. 相似文献
239.
240.