2,261 research outputs found

    Characterisation of a global collection of Dothistroma pini isolates : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Molecular Biology at Massey University, Palmerston North, New Zealand

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    Dothistroma pini is a filamentous fungus which infects Pinus radiata, New Zealand's predominant forest species. Dothistroma blight causes premature defoliation, a reduction in the rate of growth and, in extreme cases, death of the trees. This forest pathogen produces a toxin, dothistromin, which is implicated in the development of the disease symptoms. Only one strain of D. pini is thought to be present in New Zealand. However, world-wide there is a diverse range including the sexual form. A collection of D. pini strains from eight countries was collated in the UK. To prevent further introductions of 'foreign' D. pini to New Zealand and to assist in the identification and appropriate containment, should a new outbreak of needle blight occur, the D. pini isolates in this collection were characterised at both the species and individual strain level. Sequence analysis of the ribosomal internal transcribed spacer (ITS) and the production of dothistromin by the isolates in the collection confirmed all were D. pini. Quantification of the levels of dothistromin produced by the isolates, in culture, showed a large variation between the strains. Isolates MINI11, NEB8, GUA1 and, in particular, ALP3 produced significantly more dothistromin than NZE1. Changes in culture environment and media types were shown to affect the levels of dothistromin produced by the D. pini isolates. However, these changes were not sufficient to support the production of aflatoxin. To analyse the genetic diversity among the overseas D. pini isolates, a robust microsatellite-based DNA fingerprinting system was developed. Microsatellite loci were isolated. Primers designed to flank the microsatellite repeats were used for PCR amplification in the 'core' twelve D. pini strains. The unique fingerprint patterns obtained from these loci were used to distinguish the isolates to the individual strain level. This system of identification provides an effective tool for screening and prognosis of infected pine forest sites

    Surplus Liquidity: Implications for Central Banks

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    Surplus liquidity occurs where cashflows into the banking system persistently exceed withdrawals of liquidity from the market by the central bank. This is reflected in holdings of reserves in excess of the central bank's required reserves. The occurrence of surplus liquidity is widespread, covering many countries around the world. Historically, it has been observed most often in Soviet, wartime and transitional countries. Transitional economies, for example, often attract large capital inflows as the economy opens and undergoes privatisation. The effect of these inflows on liquidity is often magnified by central bank intervention in the foreign exchange market when there is upward pressure on the domestic currency. In the wartime economy, consumption is restricted and large amounts of involuntary savings accumulate until goods and services eventually become more widely available. Soviet-style economies have displayed widespread shortages and administered prices. This creates a situation of repressed inflation, whereby prices are too low relative to the money stock, leaving individuals with excess real balances. The importance of surplus liquidity for central banks is threefold and lies in its potential to influence: (1) the transmission mechanism of monetary policy; (2) the conduct of central bank intervention in the money market, and (3) the central bank's balance sheet and income.Surplus Liquidity, Implications,Central Banks

    A syntaxin 10-SNARE complex distinguishes two distinct transport routes from endosomes to the trans-Golgi in human cells

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    Mannose 6-phosphate receptors (MPRs) are transported from endosomes to the Golgi after delivering lysosomal enzymes to the endocytic pathway. This process requires Rab9 guanosine triphosphatase (GTPase) and the putative tether GCC185. We show in human cells that a soluble NSF attachment protein receptor (SNARE) complex comprised of syntaxin 10 (STX10), STX16, Vti1a, and VAMP3 is required for this MPR transport but not for the STX6-dependent transport of TGN46 or cholera toxin from early endosomes to the Golgi. Depletion of STX10 leads to MPR missorting and hypersecretion of hexosaminidase. Mouse and rat cells lack STX10 and, thus, must use a different target membrane SNARE for this process. GCC185 binds directly to STX16 and is competed by Rab6. These data support a model in which the GCC185 tether helps Rab9-bearing transport vesicles deliver their cargo to the trans-Golgi and suggest that Rab GTPases can regulate SNARE–tether interactions. Importantly, our data provide a clear molecular distinction between the transport of MPRs and TGN46 to the trans-Golgi

    Murky Materiality & Scattered Standards: In Favor of a More Uniform System of SST Disclosure Requirements

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    The Securities and Exchange Commission (SEC) requires corporations to disclose their business in or with state sponsors of terrorism (SSTs). The SEC solicits these disclosures with varying standards arising under several different mechanisms. These mechanisms include the requirements of the materiality standard, the provisions of Regulation S-K, targeted inquiry in individually issued comment letters, and affirmative requirements mandated under specific legislation. Each of these mechanisms requires disclosure of slightly different information regarding SSTs with varying degrees of exactitude. This Note examines the SEC’s current SST disclosure framework, considering the benefits, as well as the criticisms, of these disclosure mandates. This Note concludes that, although SST disclosure mandates are important, the mechanisms in place result in inconsistent disclosure that renders the entire framework ineffective. This Note argues that a more consistent SST disclosure standard is needed and proposes the addition of a new line item to Regulation S-K mandating that companies disclose all of their business in or with SSTs

    Are Stable Coins Stable? Stable Coins\u27 Exposure to Cryptocurrency and Financial Market Volatility

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    Stable coins are the nonvolatile assets that assist cryptocurrency investors in hedging from the volatility of the market. These coins have market capitalizations worth billions of US dollars and are relied on throughout the world to store funds without risk. However, there have been instances in the past of stable coins failing and wiping out billions from the market. In this analysis, I examine the exposure that the four largest stable coins have to market movements in both cryptocurrency markets and traditional financial markets. I find that one stable coin, DAI is the only coin that has no correlation or granger-causal relationships with either market. Tether is found to have a statistically significant correlation with the S&P 500, and the S&P 500 granger-causes price returns in USDC. Finally, there was a statistically significant correlation between cryptocurrency market price returns and the price returns of BUSD. These results show that DAI is the most trustworthy cryptocurrency in hedging from market risks. The research displays weaknesses that each coin has that investors should take into account when investing

    Palestinian Power in Lebanon: The Development of Palestinian Militancy and its Role in the Outbreak of the Lebanese Civil War

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    The Lebanese Civil War was a violent, destructive conflict that plagued Lebanon for fifteen years and left the country, and its capital city of Beirut in particular, completely devastated. The outbreak of civil war in 1975 was the product of a combination of factors, both internal and external, that had been developing within Lebanon since the Ottoman period and even earlier. The country had long been fragmented as a result of sectarianism and was further divided by the unique political climate that developed in the aftermath of independence in 1943. However, sectarianism and internal political divide, although necessary, were not sufficient to trigger such a violent and long-lasting conflict, evidenced by the fact that smaller clashes between religious and political groups had occurred in the past, but never escalated to the degree and intensity of the civil war in 1975. Beginning in the 1960s and 70s, the growing nationalist activism of the Palestinian refugee population in Lebanon and the increasing political and military power of the PLO and other Palestinian organizations deeply affected religious and political groups at both ends of the political spectrum, intensifying sectarian strife and political discord. While some groups fought to maintain the current political and social system, others, motivated by the actions of the Palestinian organizations, used the Palestinian military presence in Lebanon as a means to alter a system that did not accurately represent their interests. The political and military activity of the PLO and other Palestinian organizations in Lebanon was the catalyst that set the war in motion, escalating tensions in an already divided society

    The external characteristics of valid multiple-choice test items used in achievement tests

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    Thesis (Ed.D.)--Boston University. This item was digitized by the Internet Archive

    Relative efficiency measurement in the public sector with data envelopment analysis

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    PhDTraditional efficiency measures have two significant drawbacks. Firstly, they fail to recognise that output is the result of all inputs operating in combination; thus output per head is a misleading indicator of intrinsic labour productivity. Secondly, they have often been defined in terms of average levels of performance in least squares production functions. In practice, average performance norms may institutionalise some level of inefficiency. The first of these problems may be overcome in a total-factor view of efficiency. This implies the extension of traditional ratio measures to include all inputs and outputs simultaneously. The second requires the comparison of performance with frontier possibilities. Both of these improvements are embodied in Data Envelopment Analysis (DEA). Two applications of DEA are undertaken on U. K. public sector data. The first of these defines frontier efficiency in local education authorities (LEAs). It develops an 8 variable model with 3 outputs (based on exam pass rates) and 5 inputs. Four of the inputs are uncontrollable background variables allowing for differences in student catchment area; the fifth, teaching expenditure, is under LEA control and can be targeted. The results suggest that 44 authorities are best-practice and at the remainder spending per pupil could have been reduced by an average of 6.8%. These results are replicated on smaller clusters of LEAs to examine the sensitivity of DEA to the size of the performance comparison. The clustering procedure produces marked effects on targets, peer groups and the efficiency status of certain authorities. A second case study investigates the performance of a sample of 33 prisons with a high remand population. The model separately identifies the effects of remand prisoners on costs, and includes separate variables to reflect the levels of overcrowding and offences. In 1984/85 the combined budget of these prisons was overspent by 4.6% vis a vis best-practice costs. Using an alternative constant returns technology this overspend rises to 13.1%. Two aspects of DEA targets are explored. A model of Leibenstein's inert area suggests reasons for the persistence of inefficiency and hence that targets may be unattainable without coercion. Secondly, the literature has justified the recommendation of DEA targets in their being Pareto efficient. This interpretation is disputed and an alternative DEA-Dominance criterion is proposed as a more appropriate basis for targeting

    Progress towards the Kinetic Characterization of PhaG, a Key Enzyme in the Biosynthesis of Poly-[(R)-3-hydroxyalkanoates] in Bacteria

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    Poly-[(R)-3-hydroxyalkanoates] (PHAs) are biodegradable polyesters produced by diverse microbial strains and genetically modified organisms. Increasing our understanding of different metabolic pathways within PHA-producing organisms is highly desired so as to bolster PHAs as economically competitive alternatives to petroleum-based plastics. Some pseudomonads, including Pseudomonas putida, Pseudomonas aeruginosa, and Pseudomonas oleovorans, commonly biosynthesize PHA polyesters composed of side chains containing between 6-14 carbons (medium chain length or MCL PHAs) derived from intracellular fatty acid feedstocks. The metabolic link between fatty acids and PHA biosynthesis is the enzyme PhaG, which was reported to exhibit 3-hydroxyacyl-ACP:CoA transferase activity. However, recent studies have suggested PhaG can alternatively function as a 3-hydroxyacyl-ACP thioesterase to produce free 3-hydroxyfatty acids which, coupled with a 3-hydroxyfatty acid:CoA ligase (AlkK), yields the CoA-activated substrates needed for polymerization by the PHA synthase, PhaC. In this study, we hypothesize that PhaG acts preferentially as a 3- hydroxyacyl-ACP thioesterase, effectively increasing the pool of free 3-hydroxyfatty acids available for their downstream CoA activation and polymerization. To test our hypothesis we cloned phaG (PP 1408) from P. putida KT2440 into expression plasmids, and heterologously expressed/purified PhaG fused with either N or C terminal polyhistidine tags. To investigate the enzyme\u27s activity in vitro, an N-acetylcysteamine (SNAC) thioester of rac-3-hydroxydecanoic acid was synthesized. Additionally, we are performing the enantioselective syntheses of (R)-3-hydroxydecanoic acid and its SNAC analog to carry out a thorough kinetic analysis of PhaG
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