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Search Results: 1 - 10 of 303151 matches for " Alex J Dunnett "
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A spatially explicit whole-system model of the lignocellulosic bioethanol supply chain: an assessment of decentralised processing potential
Alex J Dunnett, Claire S Adjiman, Nilay Shah
Biotechnology for Biofuels , 2008, DOI: 10.1186/1754-6834-1-13
Abstract: Ethanol production costs for current technologies decrease significantly from $0.71 to $0.58 per litre with increasing economies of scale, up to a maximum single-plant capacity of 550 × 106 l year-1. The development of high-yielding energy crops and consolidated bio-processing realises significant cost reductions, with production costs ranging from $0.33 to $0.36 per litre. Increased feedstock yields result in systems of eight fully integrated plants operating within a 500 × 500 km2 region, each producing between 1.24 and 2.38 × 109 l year-1 of pure ethanol. A limited potential for distributed processing and centralised purification systems is identified, requiring developments in modular, ambient pretreatment and fermentation technologies and the pipeline transport of pure ethanol.The conceptual and mathematical modelling framework developed provides a valuable tool for the assessment and optimisation of the lignocellulosic bioethanol supply chain. In particular, it can provide insight into the optimal configuration of multiple plant systems. This information is invaluable in ensuring (near-)cost-optimal strategic development within the sector at the regional and national scale. The framework is flexible and can thus accommodate a range of processing tasks, logistical modes, by-product markets and impacting policy constraints. Significant scope for application to real-world case studies through dynamic extensions of the formulation has been identified.The penetration of biomass-derived ethanol (bioethanol) into the road transport fuels market has the potential to reduce greenhouse gas (GHG) emissions, improve fuel security, stimulate the agricultural sector and provide new markets for technology development and application. The 2006 global market for bioethanol was 20.2 million tonnes oil equivalent (mtoe), and was dominated by US and Brazilian production and consumption (45.4% and 43.9% of the total, respectively). Global growth (averaging 10.9% since 2001) has be
Percepción del público hacia plantaciones de herbáceas ornamentales
García-Albarado, J. C.;Dunnett, N.;
Revista Chapingo. Serie horticultura , 2009,
Abstract: studies in environmental psychology in north america and western europe suggest that people of the city tend to value the contact with nature. an ecological style, naturalistic approach, might be an appropriate alternative because it promotes the minimal use of inputs in the establishment and management of planting schemes (substrates, fertilizers) it consideres species adapted to the site and it promotes widespread acceptance amoungst users. however, there is evidence of a difference in perception towards these alternatives according to age and gender of the public. therefore this research aimed to study the perceptions of users (n = 300) according to these variables into ecological and formal herbaceous plantings, both located in the main entrance of endcliffe park in sheffield, uk. thus, the professional landscape designers could consider these principles to design more sustainable plantatings with a more "democratic" sense. this could be done by considering the positive aspects of both plantings. the evaluation was done by questionnaire in site. the results indicated more positive attitudes towards the ecological planting by women and users between 31 and 60 years of age. by contrast, formal plantings were perceived more positively by men and the group of 18 to 30 and up to 61 years of age. the differences found in men and women and age may be due to cultural factors or evolutionary theories. through this study there were found positive aspects that could let to promote more sustainable planting schemes with greater acceptance by the laid public.
Phylogenetic biodiversity assessment based on systematic nomenclature
Ross H Crozier,Lisa J Dunnett,Paul-Michael Agapow
Evolutionary Bioinformatics , 2005,
Abstract: Biodiversity assessment demands objective measures, because ultimately conservation decisions must prioritize the use of limited resources for preserving taxa. The most general framework for the objective assessment of conservation worth are those that assess evolutionary distinctiveness, e.g. Genetic (Crozier 1992) and Phylogenetic Diversity (Faith 1992), and Evolutionary History (Nee & May 1997). These measures all attempt to assess the conservation worth of any scheme based on how much of the encompassing phylogeny of organisms is preserved. However, their general applicability is limited by the small proportion of taxa that have been reliably placed in a phylogeny. Given that phylogenizaton of many interesting taxa or important is unlikely to occur soon, we present a framework for using taxonomy as a reasonable surrogate for phylogeny. Combining this framework with exhaustive searches for combinations of sites containing maximal diversity, we provide a proof-of-concept for assessing conservation schemes for systematized but un-phylogenised taxa spread over a series of sites. This is illustrated with data from four studies, on North Queensland flightless insects (Yeates et al. 2002), ants from a Florida Transect (Lubertazzi & Tschinkel 2003), New England bog ants (Gotelli & Ellison 2002) and a simulated distribution of the known New Zealand Lepidosauria (Daugherty et al. 1994). The results support this approach, indicating that species, genus and site numbers predict evolutionary history, to a degree depending on the size of the data set.
Phylogenetic biodiversity assessment based on systematic nomenclature
Ross H Crozier,Lisa J Dunnett,Paul-Michael Agapow
Evolutionary Bioinformatics , 2006,
Abstract: Biodiversity assessment demands objective measures, because ultimately conservation decisions must prioritize the use of limited resources for preserving taxa. The most general framework for the objective assessment of conservation worth are those that assess evolutionary distinctiveness, e.g. Genetic (Crozier 1992) and Phylogenetic Diversity (Faith 1992), and Evolutionary History (Nee & May 1997). These measures all attempt to assess the conservation worth of any scheme based on how much of the encompassing phylogeny of organisms is preserved. However, their general applicability is limited by the small proportion of taxa that have been reliably placed in a phylogeny. Given that phylogenizaton of many interesting taxa or important is unlikely to occur soon, we present a framework for using taxonomy as a reasonable surrogate for phylogeny. Combining this framework with exhaustive searches for combinations of sites containing maximal diversity, we provide a proof-of-concept for assessing conservation schemes for systematized but un-phylogenised taxa spread over a series of sites. This is illustrated with data from four studies, on North Queensland flightless insects (Yeates et al. 2002), ants from a Florida Transect (Lubertazzi & Tschinkel 2003), New England bog ants (Gotelli & Ellison 2002) and a simulated distribution of the known New Zealand Lepidosauria (Daugherty et al. 1994). The results support this approach, indicating that species, genus and site numbers predict evolutionary history, to a degree depending on the size of the data set.
Potential cellular and regenerative approaches for the treatment of Parkinson’s disease
Emma L Lane,Olivia J Handley,Anne E Rosser,Stephen B Dunnett
Neuropsychiatric Disease and Treatment , 2008,
Abstract: Emma L Lane, Olivia J Handley, Anne E Rosser, Stephen B DunnettBrain Repair Group, School of Biosciences, Cardiff University, CF10 3US, UKAbstract: Parkinson’s disease is most commonly treated with a range of pharmacotherapeutics, with the more recent introduction of surgical techniques including deep-brain stimulation. These have limited capabilities to improve symptoms of the disease in more advanced stages, thus new therapeutic strategies including the use of viral vectors and stem cells are in development. Providing a continuous supply of dopamine to the striatum in an attempt to improve the treatment of motor symptoms using enzymes in the dopamine synthesis and machinery is one approach. Alternatively, there are tools which may serve to both protect and encourage outgrowth of surviving neurons using growth factors or to directly replace lost innervation by transplantation of primary tissue or stem cell-derived dopaminergic neurons. We summarize some of the potential therapeutic approaches and also consider the recent EU directives on practical aspects of handling viral vectors, cells and tissues, and in the running of clinical trials in Europe which impact on their development.Keywords: transplantation, viral vector, stem cells, ethics, European Union directive
Family Forest Owners’ Motivation to Control Understory Vegetation: Implications for Consulting Forestry  [PDF]
Alex C. Londeau, Thomas J. Straka
Open Journal of Forestry (OJF) , 2013, DOI: 10.4236/ojf.2013.34016
Abstract:

Forest vegetation management has evolved as a recognized component of intensive forest management practice. It involves the management of competing vegetation necessary to obtain the high yields expected in modern forest plantations via control of interfering plants that influence regeneration outcome, impact timber stand development, and limit native plant and wildlife diversity. It includes cultural control, fire control, mechanical control, biological control, and chemical control. The public perception of forest vegetation management, especially chemical control, is sometimes negative due to health and environmental concerns. It is an important tool in the forest management alternatives available to consulting foresters managing family forest lands (the vast majority of private forest land in the United States). We report on a study that addresses the motivations of family forest owners that implement forest vegetation management practices and the motivation of those who chose not to implement after forester recommendations to do so. For those who do implement forest vegetation management, improvement of wildlife habitat and increased timber growth was the main motivation. For those who did not, cost was the main concern. Size of forest holding plays a major role in determining who will practice intensive forestry.

 

A Lie connection between Hamiltonian and Lagrangian optics
Alex J. Dragt
Discrete Mathematics & Theoretical Computer Science , 1997,
Abstract: It is shown that there is a non-Hamiltonian vector field that provides a Lie algebraic connection between Hamiltonian and Lagrangian optics. With the aid of this connection, geometrical optics can be formulated in such a way that all aberrations are attributed to ray transformations occurring only at lens surfaces. That is, in this formulation there are no aberrations arising from simple transit in a uniform medium. The price to be paid for this formulation is that the Lie algebra of Hamiltonian vector fields must be enlarged to include certain non-Hamiltonian vector fields. It is shown that three such vector fields are required at the level of third-order aberrations, and sufficient machinery is developed to generalize these results to higher order.
What is a Systems Approach?
Alex J. Ryan
Physics , 2008,
Abstract: What is a systems approach? The first step towards answering this question is an understanding of the history of the systems movement, which includes a survey of contemporary systems discourse. In particular, I examine how systems researchers differentiated their contribution from mechanistic science - but also from holistic doctrines; and identify the similarities and sharpest differences between complex systems and other systems approaches. Having set the scene, the second step involves developing a definition of 'system' consistent with the spirit of the systems approach.
Emergence is coupled to scope, not level
Alex J. Ryan
Physics , 2006,
Abstract: Since its application to systems, emergence has been explained in terms of levels of observation. This approach has led to confusion, contradiction, incoherence and at times mysticism. When the idea of level is replaced by a framework of scope, resolution and state, this confusion is dissolved. We find that emergent properties are determined by the relationship between the scope of macrostate and microstate descriptions. This establishes a normative definition of emergent properties and emergence that makes sense of previous descriptive definitions of emergence. In particular, this framework sheds light on which classes of emergent properties are epistemic and which are ontological, and identifies fundamental limits to our ability to capture emergence in formal systems.
The helix--coil transition on the worm--like chain
Alex J. Levine
Physics , 2004,
Abstract: I propose a variation of the standard worm--like chain model to account for internal order parameter (helix/coil) fields on the polymer chain. This internal order parameter field influences polymer conformational statistics by locally modifying the persistence length of the chain. Using this model, I make predictions for the bending and stretching response of an alpha-helical domain of a protein. In particular, I show that alpha-helical protein domains will buckle under applied torque. This highly nonlinear elastic behavior may be important in the understanding of allosteric control of biochemical pathways.
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