title: The Microflora of the Huhu Grub

authors: Williams, Thomas Carl

subjects: Huhu

abstract: New Zealand's endemic longhorned beetle larvae, the Huhu grub (Prionoplus reticularis) feeds on dead coniferous wood. No studies have been conducted on its gut microflora. Given that the Huhu grub feeds solely on lignocelluloses, it is likely that there are microorganisms present in its gut which are capable of degrading lignocelluloses to release energy rich sugars. This process of lignocelluloses release is the rate limiting step in the utilisation of woody material for bioprocesses such as bioethanol production. Microbial communities from wild grubs were compared with those raised on laboratory diets of either: lignocellulose, cellulose, or complex nutrients. Bacterial gut communities were surveyed using 454 pyrosequencing of the variable 5 and 6 regions (400nt reads) of bacterial 16S rRNA genes as well as clone library analysis of the full length gene (1500bp). Fungal gut communities were analysed using cloning and Sanger sequencing of amplified fungal intergenic spacer (ITS) regions. The wild type gut bacterial population was highly diverse, with no known cellulose or lignin degraders detected in any abundance, although a strain of Burkholderia thought to be capable of nitrogen fixation was detected. No methanogenic archaea or acetogenic bacteria were detected. Fungal ITS sequences had high similarity with those of known lignin, hemicellulose and cellulose degraders in the public databases, and an uncultured Basidiomycete made up 51% of the wild type community, while species of the Penicillium genus dominated the grubs reared on laboratory diets of lignocellulose. When grubs were reared on a diet of only cellulose the fungal community was dominated by a single species identified as Candida shehatae, a hemicellulose degrader known to associate with other longhorned beetle larvae. These fungi may be of interest for the biological conversion of lignocelluloses.

text: The Microflora of the Huhu Grub New Zealand's endemic longhorned beetle larvae, the Huhu grub (Prionoplus reticularis) feeds on dead coniferous wood. No studies have been conducted on its gut microflora. Given that the Huhu grub feeds solely on lignocelluloses, it is likely that there are microorganisms present in its gut which are capable of degrading lignocelluloses to release energy rich sugars. This process of lignocelluloses release is the rate limiting step in the utilisation of woody material for bioprocesses such as bioethanol production. Microbial communities from wild grubs were compared with those raised on laboratory diets of either: lignocellulose, cellulose, or complex nutrients. Bacterial gut communities were surveyed using 454 pyrosequencing of the variable 5 and 6 regions (400nt reads) of bacterial 16S rRNA genes as well as clone library analysis of the full length gene (1500bp). Fungal gut communities were analysed using cloning and Sanger sequencing of amplified fungal intergenic spacer (ITS) regions. The wild type gut bacterial population was highly diverse, with no known cellulose or lignin degraders detected in any abundance, although a strain of Burkholderia thought to be capable of nitrogen fixation was detected. No methanogenic archaea or acetogenic bacteria were detected. Fungal ITS sequences had high similarity with those of known lignin, hemicellulose and cellulose degraders in the public databases, and an uncultured Basidiomycete made up 51% of the wild type community, while species of the Penicillium genus dominated the grubs reared on laboratory diets of lignocellulose. When grubs were reared on a diet of only cellulose the fungal community was dominated by a single species identified as Candida shehatae, a hemicellulose degrader known to associate with other longhorned beetle larvae. These fungi may be of interest for the biological conversion of lignocelluloses.

year: 2011

title: Portfolio structure and optimisation of momentum returns

authors: Gupta, Kartick

subjects: momentum returns

abstract: This study analyses momentum returns in 54 countries covering 34 years.  It is the first study where optimising programmes are applied to momentum returns and portfolio selection.  Momentum returns have remained a contentious topic and a substantial amount of research purports to support and negate this anomaly.  Momentum studies have previously concentrated on finding the cause of this anomaly or determining whether abnormal returns are present only in a particular dataset.  However, there is no clear consensus regarding how to construct/implement a momentum strategy.  To date it has been unclear as to how many portfolios should be created, whether or not the portfolios should be equally-weighted or value-weighted and how the momentum returns will change when a chosen strategy is constructed/implemented compared to an alternative strategy.  This lack of precision concerning how to construct/implement momentum strategy potentially leads to confounding results.  This current thesis contributes to an understanding of the  structure impact effect  by computing momentum returns for changing portfolio structures and observing the magnitude of the impact on returns on a specially crafted database of 52,593 stocks from 54 countries over the time period 1973-2007.
The two important empirical extensions are the industrial momentum and the 52-week high momentum models.  Both the industrial momentum and 52-week high momentum strategies claim that their returns are superior to the traditional momentum return and possess superior explanatory power.  Empirical evidence, to date, has not been available to attest to whether the results hold true when applied in different markets.  This gap in knowledge motivated this research investigation of multiple countries addressing how different methods of calculating returns, different approaches to momentum strategy, different portfolio weighting process impact upon the robustness of results.
This research also addresses the question of whether momentum returns can be increased through the use of optimisation algorithms.  Traditionally, little attention has been paid to the portfolio weighting with either an equal-weighted or value-weighted approach to allocating funds to the Winner and Loser portfolios.  This study proposes an alternative way of allocating money to the Winner and Loser portfolios with the goal of generating increased returns.  Eight different algorithms are applied to the share returns to determine whether one method is clearly superior to others in maximising the momentum returns for the synthesised portfolios over a period of time.  This is the first study of its type where optimising programmes are applied to momentum returns and portfolio selection and covers several countries.
The results indicate that momentum returns are robust on a global scale and the returns are by and large statistically significant under different portfolio construction approaches.  Both the industrial and 52-week momentum strategies remain positive and statistically significant but do not generate the same magnitude of returns as the conventional momentum return model.  The optimisation of momentum return shows promising results as a number of optimisation techniques do enhance momentum returns.    As the potential to increase returns becomes known, traders will quickly react and there is likely to be a range of new investment products arising.

text: Portfolio structure and optimisation of momentum returns This study analyses momentum returns in 54 countries covering 34 years.  It is the first study where optimising programmes are applied to momentum returns and portfolio selection.  Momentum returns have remained a contentious topic and a substantial amount of research purports to support and negate this anomaly.  Momentum studies have previously concentrated on finding the cause of this anomaly or determining whether abnormal returns are present only in a particular dataset.  However, there is no clear consensus regarding how to construct/implement a momentum strategy.  To date it has been unclear as to how many portfolios should be created, whether or not the portfolios should be equally-weighted or value-weighted and how the momentum returns will change when a chosen strategy is constructed/implemented compared to an alternative strategy.  This lack of precision concerning how to construct/implement momentum strategy potentially leads to confounding results.  This current thesis contributes to an understanding of the  structure impact effect  by computing momentum returns for changing portfolio structures and observing the magnitude of the impact on returns on a specially crafted database of 52,593 stocks from 54 countries over the time period 1973-2007.
The two important empirical extensions are the industrial momentum and the 52-week high momentum models.  Both the industrial momentum and 52-week high momentum strategies claim that their returns are superior to the traditional momentum return and possess superior explanatory power.  Empirical evidence, to date, has not been available to attest to whether the results hold true when applied in different markets.  This gap in knowledge motivated this research investigation of multiple countries addressing how different methods of calculating returns, different approaches to momentum strategy, different portfolio weighting process impact upon the robustness of results.
This research also addresses the question of whether momentum returns can be increased through the use of optimisation algorithms.  Traditionally, little attention has been paid to the portfolio weighting with either an equal-weighted or value-weighted approach to allocating funds to the Winner and Loser portfolios.  This study proposes an alternative way of allocating money to the Winner and Loser portfolios with the goal of generating increased returns.  Eight different algorithms are applied to the share returns to determine whether one method is clearly superior to others in maximising the momentum returns for the synthesised portfolios over a period of time.  This is the first study of its type where optimising programmes are applied to momentum returns and portfolio selection and covers several countries.
The results indicate that momentum returns are robust on a global scale and the returns are by and large statistically significant under different portfolio construction approaches.  Both the industrial and 52-week momentum strategies remain positive and statistically significant but do not generate the same magnitude of returns as the conventional momentum return model.  The optimisation of momentum return shows promising results as a number of optimisation techniques do enhance momentum returns.    As the potential to increase returns becomes known, traders will quickly react and there is likely to be a range of new investment products arising.

year: 2010

title: Hostile shores: catastrophic events in prehistoric New Zealand and their impact on Maori coastal communities [Book Review]

authors: Lowe, David J.

abstract: This article reviews the book: “Hostile shores: catastrophic events in prehistoric New Zealand and their impact on Maori coastal communities”, by Bruct McFadgen.

text: Hostile shores: catastrophic events in prehistoric New Zealand and their impact on Maori coastal communities [Book Review] This article reviews the book: “Hostile shores: catastrophic events in prehistoric New Zealand and their impact on Maori coastal communities”, by Bruct McFadgen.

year: 2008