762 research outputs found
Evolution of the genera Vitex (Lamiaceae) and Zygogynum (Winteraceae) on New Caledonia
The New Caledonia archipelago is home to a richly diverse flora including a disproportionate number of lineages whose heritage can be traced to ancient Gondwana. Much of this species richness is owed to the complex geologic history, including an extensive period of submersion, of the region which actively shaped the flora over millennia. Given such complexity there is always unknowns both with regards to the circumscription of such a diverse flora and to understanding aspects of the archipelagos geologic past, which in many cases prove extremely difficult to resolve. This thesis investigates two aspects of this notion using modern day molecular techniques.
The first aspect that we investigate is the question of species circumscription with regards to Vitex (Lamiaceae). Here we scrutinize the monophyly of the morphologically variable species Vitex collina, as described by Mabberley (1990), previously suggested by Mabberley to comprise a minimum of three distinct morphotypes. Additionally we consider the genetic uniqueness of a recently discovered species, tentatively named Vitex sp. “unifolia”, from currently accepted New Caledonian Vitex collina s.l. Maximum likelihood (ML) analyses using the internal transcribed spacer (ITS) genetic loci revealed that New Caledonian Vitex collina is paraphyletic with New Zealand V. lucens and Australian V. lignum-vitae nested within a well-supported V. collina s.l. clade. Our results suggest a minimum of two genetically distinct entities within V. collina, though the new species Vitex sp. “unifolia” was not distinguished genetically from Vitex cf. “collina”. The additional morphological analysis in light of our molecular analyses revealed further distinction of taxa within our sample group. This revealed a potential for three separate morphological entities within Vitex collina s.l. specimens, with Vitex sp. “unifolia” representing a fourth. Further research will result in the formal recognition of Vitex sp. “unifolia” upon publication, as well as further delimitation of the distinct entities within V. collina s.l. These revisions will have implications for the conservation status of these revised species, especially with regards to the rare Vitex sp. “unifolia”.
The second aspect investigated New Caledonian Winteraceae focussing on two research aims. The first aim scrutinised the New Caledonian Zygogynum s.l. in light of revisions made in Vink (1988; 1993; 2003), where four previously recognised genera (Belliolum, Bubbia, Exospermum, and Zygogynum) were dismantled into a single broadly circumscribed genus. The second aim was to assess any major morphological trends within Zygogynum s.l. and biogeographic patterns within the Winteraceae. Maximum Likelihood and Bayesian analyses using the internal transcribed spacer (ITS) and psbA-trnH genetic loci confirmed the monophyly and position of Takhtajania, Tasmannia, Drimys, and Pseudowintera within the Winteraceae. New Caledonian Zygogynum s.l. was shown to be paraphyletic with Z. schlechteri nested within a distinct Australian Bubbia clade separate from remaining Zygogynum. Our analyses showed no support for the distinction of species previously belonging to Belliolum and Exospermum with all remaining Zygogynum forming a monophyletic clade. The monophyly of species within the Zygogynum were for the most part resolved, with only few species left unresolved or paraphyletic relationships. Further investigation of biogeography within the Winteraceae revealed that Zealandic Winteraceae share their common ancestor with South American taxa, reflecting the Gondwanic roots of this family, with Australian Bubbia having originated from New Caledonian Zygogynum. From this we suggest, upon further investigation, that the retention of Bubbia within Zygogynum s.l. was supported and should be maintained. Alternately, if Bubbia is maintained as distinct from Zygogynum s.l., Z. schlechteri will be revised to Bubbia schlechteri. Further research including specimens of all described taxa will improve the resolution of our analyses, likely identifying further inconsistences that require revision or attention. Our investigation into morphological trends within the Zygogynum uncovered a trend of carpel evolution, in which a single well supported clade of Zygogynum exhibit fused carpels with all others within the family exhibiting unfused gynoecia. The significance of this is that it is a derived trait recognised as a reoccurring trend within the Angiosperm lineage, though this is the first instance where it has been identified occurring within a single genus
Dairy development for the resource poor. Part 1: a comparison of dairy policies and development in South Asia and East Africa
The process of dairy development that this study addresses is driven by underlying
fundamental changes in economic growth, the value of resources and consumer
demand. However, it is also shaped by public policies, interventions and investment
decisions and will be accompanied by changes in impact on incomes, opportunities
and livelihoods of producers and changes in opportunities and returns for market
agents and investors. This study examines dairy development in two key dairy
producing regions in the developing world: East Africa and South Asia. The aim of the
study is to analyse the trends in dairy development in these two regions and identify
their key determinants, to assess the impact of policy interventions on those trends
and to identify impacts of dairy development, particularly on the poor.
The study is reported in three parts: Part 1 presents a conceptual framework for dairy
development, followed by a section presenting a regional analysis of dairy
development trends across all the countries in the two regions and a synthesis of the
outcomes of the case study analyses, highlighting implications for policy interventions
and investment, including proposing a model for pro-poor dairy development. Parts 2
and 3 consist of in-depth case studies and analyses of dairy development trends,
determinants and outcomes in Kenya and Ethiopia (Part 2) and India and Pakistan
(Part 3)
Dairy development for the resource poor. Part 2: Kenya and Ethiopia. Dairy development case studies
The process of dairy development that this study addresses is driven by underlying
fundamental changes in economic growth, the value of resources and consumer
demand. However, it is also shaped by public policies, interventions and investment
decisions and will be accompanied by changes in impact on incomes, opportunities
and livelihoods of producers and changes in opportunities and returns for market
agents and investors. This study examines dairy development in two key dairy
producing regions in the developing world: East Africa and South Asia. The aim of the
study is to analyse the trends in dairy development in these two regions and identify
their key determinants, to analyse the impact of policy interventions on those trends
and to identify impacts of dairy development, particularly on the poor.
The study is reported in three parts: Part 1 presents a conceptual framework for dairy
development, followed by a section presenting a regional analysis of dairy
development trends across all the countries in the two regions and a synthesis of the
outcomes of the case study analyses (see below), highlighting implications for policy
interventions and investment, including proposing a model for pro-poor dairy
development. Parts 2 and 3 consist of in-depth case studies and analyses of dairy
development trends, determinants and outcomes in Kenya and Ethiopia (Part 2 – this
report) and India and Pakistan (Part 3)
Dairy development for the resource poor. Part 3: Pakistan and India dairy development case studies
The process of dairy development that this study addresses is driven by underlying
fundamental changes in economic growth, the value of resources and consumer
demand. However, it is also shaped by public policies, interventions and investment
decisions and will be accompanied by changes in impact on incomes, opportunities
and livelihoods of producers and changes in opportunities and returns for market
agents and investors. This study examines dairy development in two key dairy
producing regions in the developing world: East Africa and South Asia. The aim of the
study is to analyse the trends in dairy development in these two regions and identify
their key determinants, to analyse the impact of policy interventions on those trends
and to identify impacts of dairy development, particularly on the poor.
The study is reported in three parts: Part 1 presents a conceptual framework for dairy
development, followed by a section presenting a regional analysis of dairy
development trends across all the countries in the two regions and a synthesis of the
outcomes of the case study analyses (see below), highlighting implications for policy
interventions and investment, including proposing a model for pro-poor dairy
development. Parts 2 and 3 consist of in-depth case studies and analyses of dairy
development trends, determinants and outcomes in Kenya and Ethiopia (Part 2) and
India and Pakistan (Part 3 – this report)
Comparison of measured and modeled ambient hydrogen sulfide concentrations near a 4000 head swine facility
Air dispersion models are currently being used to regulate agriculture facilities and/or assess their environmental impact. As such, it is critical that these models accurately reflect these impacts. Meteorological conditions, hydrogen sulfide emissions, and downwind hydrogen sulfide concentrations at a four barn, 4000-head, swine finishing facility in Northeast Iowa were measured for a three week period in October 2003. Meteorological conditions and hydrogen sulfide emissions from the barns were used as inputs into two air dispersion models, INPUFF-2 and AERMOD. Model results were compared to measured results at eighteen receptor locations. Results indicate the models did not accurately predict spatial and temporal ambient concentrations. However, a rank order comparison of data (not matched in space and time) shows the models may be useful in predicting maximum concentrations over a period of time
Fractionation of microbial populations in a PHA accumulating mixed culture and associated PHA content and composition
The uniformity of PHA composition and content across groups of organisms in mixed cultures was considered. An activated sludge microbial community, with an average PHA content of 20 wt%, was fractioned by Percoll assisted buoyant density separation. The microbial community in the two principal fractions was characterised using amplicon pyrosequencing. While organisms were common to both fractions, the relative abundances of species were found to be different between the two fractions. The average PHA content in one of the fractions was found to be higher (24 wt%) than the other (16 wt%); separation was considered to be in part driven by the density difference associated with PHA content, but also by other factors such as cell dimension and cellular morphology. But while differences in PHA content were observed, the PHA composition in both fractions was found to be approximately the same (43-44 mol% HV), which shows that distinct groups of microbial populations within mixed cultures may generate PHA with similar average copolymer composition
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Optimal investment strategies and risk measures in defined contribution pension schemes
In this paper, we derive a formula for the optimal investment allocation (derived from a dynamic programming approach) in a defined contribution (DC) pension scheme whose fund is invested in n assets. We then analyse the particular case of n=2 (where we consider the presence in the market of a high-risk and a low-risk asset whose returns are correlated) and study the investment allocation and the downside risk faced by the retiring member of the DC scheme, where optimal investment strategies have been adopted. The behaviour of the optimal investment strategy is analysed when changing the disutility function and the correlation between the assets. Three different risk measures are considered in analysing the final net replacement ratios achieved by the member: the probability of failing the target, the mean shortfall and a value at risk (VaR) measure. The replacement ratios encompass the financial and annuitisation risks faced by the retiree. We consider the relationship between the risk aversion of the member and these different risk measures in order to understand better the choices confronting different categories of scheme member. We also consider the sensitivity of the results to the level of the correlation coefficient
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