Systems and environmental decision-making: postgraduate open learning with the Open University

Environmental issues affect everyone though the ways in which people engage with them varies a great deal. The Open University''s Masters program in environmental decision making has at its core a modular course that enables students to incorporate environmental factors into their decision making from a starting point of identifying their own environmental issues using a systems approach. Students carry out a project based on their own experience in a decision-making situation of their own choice. A framework for environmental decision making is introduced and students learn how to use the framework systematically, systemically and critically. The course has evolved since it was first introduced in 1997 as both students and the course team have learnt about environmental decision making together. This paper analyses and interprets some of the data that have emerged from students projects since the course began

Mapping expert perspectives of the aviation sector

Aviation globally is characterised by significant change and consequently the future of the sector has always been difficult to predict. This study adopts a systemic approach based on findings from exploratory interviews with UK aviation academics to: determine the roles of stakeholders in the air transport system; report the current issues facing the sector; explore how these issues interact and impact on the stakeholders in the system; and speculate on the future implications. Six core stakeholders are identified: airlines, airports, consumers, manufacturers, governing institutions and interest groups. Nine core issues are reported, namely: local environment, climate change, peak oil, the state of the economy, social norms, demographics, disruptive events, national (or international) regulations and capacity. A matrix of interactions and their impacts and implications for managing the aviation system is then presented

Which activities do those with long commutes forego, and should we care?

Commuting imposes opportunity costs on travelers since those with long commutes have less time to participate in other activities. This paper examines how commute duration is associated with activity patterns. It utilizes a two-day time use survey administered in the United Kingdom in 2014 and 2015. Focusing on full-time employees and controlling for socio-demographic characteristics, we regress time spent engaging in 22 different activities on commute duration using OLS and Cragg two-part hurdle modeling. We separately test the effects of commute duration on activity participation for men versus women and for single persons versus persons in couples. We also report the subjective well-being (SWB), specifically the hedonic affect, associated with these activities as determined by using fixed-effects panel regression. The estimations suggest that commutes are associated with time constraints and entail trade-offs, with longer commutes being associated with significantly less time engaging in most of our activities including sleep, cooking, housework, shopping/accessing services, arts/entertainment activities, TV/music time, computer games and other computer use, visiting with others, sports/exercise/outdoor activities, hobbies, volunteering, and non-work travel. Those with longer commutes are found to tend to engage in more of two activities: work and eating out. The activities those with longer commutes tend to forego run the gamut from high-SWB to low-SWB. Given that the lowest-SWB activity in our sample is commuting itself, it appears as if the substitution of nearly any activity for commuting may bring emotional benefits. In all, the results suggest that longer commutes are associated with significant emotional costs

Theta functions and arithmetic quotients of loop groups

In this paper we observe that isomorphism classes of certain metrized vector bundles over P^1-{0,infinity} can be parameterized by arithmetic quotients of loop groups. We construct an asymptotic version of theta functions, which are defined on these quotients. Then we prove the convergence and extend the theta functions to loop symplectic groups. We interpret them as sections of line bundles over an infinite dimensional torus, discuss the relations with loop Heisenberg groups, and give an asymptotic multiplication formula.Comment: 16 page

Zebrafish cDNA encoding multifunctional fatty acid elongase involved in production of eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids

Enzymes that increase the chain length of fatty acids are essential for biosynthesis of highly unsaturated fatty acids. The gLELO gene encodes a protein involved in the elongation of polyunsaturated fatty acids in the fungus Mortierella alpina. A search of the Genbank database identified several EST sequences, including one obtained from zebrafish (Danio rerio), with high similarity to gLELO. The full-length transcript, ZfELO, encoding a polypeptide of 291 amino acid residues was isolated from zebrafish liver cDNA. The predicted amino acid sequence of the open reading frame (ORF) shared high similarity with the elongases of C. elegans and human. When expressed in Saccharomyces cerevisiae, the zebrafish ORF conferred the ability to lengthen the chain of a range of C18, C20 and C22 polyunsaturated fatty acids, indicating that biosynthesis of 22:6n-3 from 18:3n-3 via a 24-carbon intermediate is not only feasible, but that one elongase enzyme can perform all three elongation steps required. The zebrafish enzyme was also able to elongate monounsaturated and saturated fatty acids, and thus demonstrates a greater level of promiscuity in terms of substrate use than any elongase enzyme described previously

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-14C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level

Molecular cloning and functional characterization of fatty acyl desaturase and elongase cDNAs involved in the production of eicosapentaenoic and docosahexanoic acids from alpha-linolenic acid in Atlantic salmon (Salmo salar)

Fish are the only major dietary source for humans of omega-3 highly unsaturated fatty acids (HUFA) and, with declining fisheries, farmed fish such as Atlantic salmon (Salmo salar) constitute an increasing proportion of the fish in the human diet. However, the current high use of fish oils, derived from wild capture marine fisheries, in aquaculture feeds is not sustainable in the longer term, and will constrain continuing growth of aquaculture activities. A greater understanding of how fish metabolise and biosynthesise HUFA may lead to effective use of more sustainable aquaculture diets. The study described here contributes to an effort to determine the molecular genetics of the HUFA biosynthetic pathway in salmon, with the overall aim being to determine mechanisms for optimising the use of vegetable oils in Atlantic salmon culture. In this paper we describe the cloning and functional characterisation of two genes from salmon involved in the biosynthesis of HUFA. A salmon desaturase cDNA, SalDes, was isolated that included an open reading frame (ORF) of 1362 bp specifying a protein of 454 amino acids. The protein sequence included all the characteristic features of microsomal fatty acid desaturases, including three histidine boxes, two transmembrane regions, and an N-terminal cytochrome b5 domain containing a haem-binding motif similar to that of other fatty acid desaturases. Functional expression in the yeast, Saccharomyces cerevisiae, showed SalDes is predominantly an omega-3 Δ5 desaturase, a key enzyme in the synthesis of eicosapentaenoic acid (20:5n-3) from α-linolenic acid (18:3n-3). The desaturase showed only low levels of Δ6 activity towards C18 polyunsaturated fatty acids. In addition, a fatty acid elongase cDNA, SalElo, was isolated that includes an ORF of 888 bp, specifying a protein of 295 amino acids. The protein sequence of SalElo includes characteristic features of microsomal fatty acid elongases, including a histidine box and a transmembrane region. Upon expression in yeast, SalElo showed broad substrate specificity for polyunsaturated fatty acids with a range of chain lengths, with the rank order being C18 > C20 > C22. Thus, all fatty acid elongase activities required for the biosynthesis of docosahexaenoic acid (22:6n-3) from 18:3n-3 are displayed by this one polypeptide product

Polyunsaturated fatty acid metabolism in Atlantic salmon (Salmo salar) undergoing parr-smolt transformation and the effects of dietary linseed and rapeseed oils

Duplicate groups of Atlantic salmon parr were fed diets containing either fish oil (FO), rapeseed oil (RO), linseed oil (LO) or linseed oil supplemented with arachidonic acid (20:4n-6; AA) (LOA) from October (week 0) to seawater transfer in March (week 19). From March to July (weeks 20-34) all fish were fed a fish oil-containing diet. Fatty acyl desaturation and elongation activity in isolated hepatocytes incubated with [1-14C]18:3n-3 increased in all dietary groups, peaking in early March about one month prior to seawater transfer. Desaturation activities at their peak were significantly greater in fish fed the vegetable oils, particularly RO, compared to fish fed FO. Docosahexaenoic acid (22:6n-3:DHA) and AA in liver and gill polar lipids (PL) increased in all dietary groups during the freshwater phase whereas eicosapentaenoic acid (20:5n-3;EPA) increased greatly in all groups after seawater transfer. The AA/EPA ratio in tissue PL increased up to seawater transfer and then decreased after transfer. AA levels and the AA/EPA ratio in gill PL were generally higher in the LOA group. The levels of 18:3n-3 in muscle total lipid were increased significantly in the LO, LOA and, to a lesser extent, RO groups prior to transfer but were reduced to initial levels by the termination of the experiment (week 34). In contrast, 18:2n-6 in muscle total lipid was significantly increased after 18 weeks in fish fed the diets supplemented with RO and LO, and was significantly greater in the FO and RO groups at the termination of the experiment. Gill PGF production showed a large peak about two months after transfer to seawater. The production of total PGF post-transfer was significantly lower in fish previously fed the LOA diet. However, plasma chloride concentrations in fish subjected to a seawater challenge at 18 weeks were all lower in fish fed the diets with vegetable oils. This effect was significant in the case of fish receiving the diet with LOA, compared to those fed the diet containing FO. The present study showed that during parr-smolt transformation in Atlantic salmon there is a pre-adaptive increase in hepatocyte fatty acyl desaturation/elongation activities that is controlled primarily by environmental factors such as photoperiod and temperature but that can also be significantly modulated by diet. Feeding salmon parr diets supplemented with rapeseed or linseed oils prevented inhibition of the desaturase activities that is induced by feeding parr diets with fish oils and thus influenced the smoltification process by altering tissue PL fatty acid compositions and eicosanoid production. These effect, in turn, had a beneficial effect on the ability of the fish to osmoregulate and thus adapt to salinity changes