9,308 research outputs found
Regeneration of the native sand dune plant Pimelea arenaria in the lower North Island, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University, Palmerston North, New Zealand
New Zealand has 300,000 ha of coastal sand dunes in which many native species and introduced plant and animal species are established. One native plant inhabiting dune ecosystems is Pimelea arenaria (Thymeleaceae), the native sand daphne, which is gynodioecious with female and hermaphrodite flower types and listed as nationally declining. The cause of the decline is unknown, but anecdotal evidence suggests recruitment failure is occurring. This thesis looked at four P. arenaria populations in the lower North Island of New Zealand The aims were (1) examine the population structure and establish whether recruitment failure was evident, (2) whether any failure was due to problems with pollination, and (3) whether house mice (Mus musculus) or birds had any impact on P. arenaria by removing fruit. The P. arenaria populations ranged from 0.53-4.05 plants/ha, with female plants comprising the smaller portion of each population, the exact sex ratios varying between the sites. The standing crop of nectar of hermaphrodite flowers is modest and varies from 24 to 56 µg/flower. The pollen:ovule ratio (1987:1), as well as casual observations, suggest that insects are the main pollen vectors. Recruitment failure in P. arenaria occurred with few or no seedlings found at any site, the maximum height above substrate and the surface area of substrate covered suggesting an adult biased population. Profuse flowering occurred (360-510 flowers/m²), leading to viable seed from both female and hermaphrodite plants. Less than 50% of seed germinated from either flower type, regardless of pollination method (natural, hand out-crossed, or autonomously selfed). Female plants observed higher germination success in seeds in both hand out-crossed and natural pollination P. arenaria seed weight remained constant between sexes and treatments, however the pulp weight was variable, with hermaphrodite autonomously selfed fruit having the smallest amount of pulp, but this was not significant (p=0.37). Graded exclosures showed that fruit was removed but this was preventable by bagging the fruit (p<0.001). However, the results from the exclosures were unable to distinguish between mice and birds suggesting that both have similar, possibly cumulative, effects on fruit loss. Within the bagged fruit there were peaks of fruit loss at the start and end of the fruiting season suggesting that selective abortion of ovules is occurring, possibly because of low abundance of pollen sources or pollen vectors Fruit loss occurred, but there was no direct field evidence of predation by mice and birds A feeding trial with mice established that both female and male mice eat and destroy P. arenaria fruit and seed, and at a low dose rate (3 fruit/mouse) the fruit of P. arenaria was not poisonous. Areas for future work are discussed for each section
Community Fisheries Management Handbook
This handbook is a unique product. It is the first "field guide" to community-based fisheries management focused specifically on fisheries, such as those of the Northwest Atlantic, that are already highly regulated by governmental authorities, with licensing and other requirements that limit access and effort. While a variety of resource materials are available on community-based natural resource management, almost all of these are written by practitioners working in the South (developing countries) and rely on case studies and techniques that have been tested in less industrialized tropical fisheries. Therefore, this handbook is one of the few publications about community-based management in 'Northern' fisheries.The need for this handbook was identified by participants working on an initiative on the Atlantic coast of Canada, "Turning the Tide: Communities Managing Fisheries Together" (www.turningthetide.ca). Turning the Tide works for improved fisheries management through community-based approaches, and through cooperative efforts among aboriginal and non-aboriginal communities. To that end, it has brought together fishermen and their communities to share information and ideas on community-based management, through events such as community forums and study tours. Participants recognized the need for a handbook on community-based fisheries management that is relevant to their own fisheries and that can be used as a tool to provide information and support for practitioners, as well as to document current practices and insights obtained, and to promote and raise public awareness about community-based fisheries management. The stories and insights in the handbook are those of Turning the Tide participants and their allies from around the Atlantic Region – the Atlantic coast of Canada and the north-eastern North America-United States – who shared this information during Turning the Tide activities, and in individual and group interviews, and who reviewed the materials used in producing this handbook. The various tools and ideas explored here are currently being applied in the region, and so the handbook demonstrates how community-based approaches to fisheries management are working today
Characterization of structural connections using free and forced response test data
The accurate prediction of system dynamic response often has been limited by deficiencies in existing capabilities to characterize connections adequately. Connections between structural components often are complex mechanically, and difficult to accurately model analytically. Improved analytical models for connections are needed to improve system dynamic preditions. A procedure for identifying physical connection properties from free and forced response test data is developed, then verified utilizing a system having both a linear and nonlinear connection. Connection properties are computed in terms of physical parameters so that the physical characteristics of the connections can better be understood, in addition to providing improved input for the system model. The identification procedure is applicable to multi-degree of freedom systems, and does not require that the test data be measured directly at the connection locations
A global approach for the identification of structural connection properties
A general procedure is developed for identifying properties of structural joints. The procedure, which uses experimental response data, is considered general because it is applicable to any size or type of structural system. The present procedure, which identifies characteristics such as damping and stiffness, accommodates both linear and nonlinear joint properties and may process test data measured at arbitrary stations on the structural system. The method identifies joint characteristics by performing a global fit between predicted and measured data. It overcomes limitations of previous methods in that it can better deal with parameter-dependent constraints (e.g., gaps). The method is demonstrated with a simplified model of a bladed disk assembly having friction damping and mistuning
Fuel containment, lightning protection and damage tolerance in large composite primary aircraft structures
The damage-tolerance characteristics of high strain-to-failure graphite fibers and toughened resins were evaluated. Test results show that conventional fuel tank sealing techniques are applicable to composite structures. Techniques were developed to prevent fuel leaks due to low-energy impact damage. For wing panels subjected to swept stroke lightning strikes, a surface protection of graphite/aluminum wire fabric and a fastener treatment proved effective in eliminating internal sparking and reducing structural damage. The technology features developed were incorporated and demonstrated in a test panel designed to meet the strength, stiffness, and damage tolerance requirements of a large commercial transport aircraft. The panel test results exceeded design requirements for all test conditions. Wing surfaces constructed with composites offer large weight savings if design allowable strains for compression can be increased from current levels
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Observations on the Interrelationships among Ants, Aphids, and Aphid Predators
Excerpt: The literature concerning the interactions of these insect groups is as interesting as it is extensive. It has generally been accepted that the relationship between ants and aphids has been one of mutualism in which ants derive all or a large part of their nutrients from aphid honeydew and perform special functions in return, primarily that of protecting aphids from their enemies. Every aspect of these associations has been covered by the excellent reviews of Nixon (1951) and Way (1963). It now appears that the nature and effectiveness of the protective value afforded the attended aphids by ants cannot be reduced to a simple statement of symbiosis. Nixon (1951) pointed out numerous situations that are responsible for fluctuations in the ant-aphid relationship. The emphasis in the present study was on the protection extended to Aphis rumicis Linn., a small aphid found on spirea shoots by the common tending ants. This restriction allowed constant surveillance of the protection supplied to a single aphid species by ants against the seasonal succession of predators. Aphid parasites were ignored in this study
Actions and Beliefs: Estimating Distribution-Based Preferences Using a Large Scale Experiment with Probability Questions on Expectations
We combine the choice data of proposers and responders in the ultimatum game, their expectations elicited in the form of subjective probability questions, and the choice data of proposers (“dictators”) in a dictator game to estimate a structural model of decision making under uncertainty. We use a large and representative sample of subjects drawn from the Dutch population. Our results indicate that there is considerable heterogeneity in preferences for equity in the population. Changes in preferences have an important impact on decisions of dictators in the dictator game and responders in the ultimatum game, but a smaller impact on decisions of proposers in the ultimatum game, a result due to proposer’s subjective expectations about responders’ decisions. The model which uses subjective data on expectations has better predictive power and lower noise level than a model which assumes that players have rational expectations. Afin de déceler un modèle structurel de prise de décision dans l'incertitude, nous combinons les données recueillies par i) les choix des deux types de joueurs dans le jeu de l'ultimatum (ceux qui proposent et ceux qui répondent), ii) leurs attentes obtenues sous la forme de questions à probabilité subjective, et iii) les choix des dictateurs (premiers joueurs) dans le jeu du dictateur. Nous utilisons un large échantillon représentatif des sujets dans la population néerlandaise. Nos résultats indiquent une hétérogénéité considérable dans la population sur les préférences en matière d'équité. La diversité de ces préférences a un impact important sur les décisions des dictateurs dans le jeu du dictateur, et sur les répondeurs dans le jeu de l'ultimatum, mais un impact plutôt moindre sur les décisions des joueurs qui proposent dans le jeu de l'ultimatum. Cette dernière observation est due aux attentes subjectives de ces joueurs face aux décisions des répondeurs. Le modèle qui utilise des données subjectives sur les attentes des joueurs prévoit mieux les choix des sujets et réduit plus le bruit qu'un modèle qui suppose que les joueurs ont des attentes rationnelles., attentes subjectives, aversion à l'injustice, jeu de l'ultimatum
Actions and Beliefs: Estimating Distribution-Based Preferences Using a Large Scale Experiment with Probability Questions on Expectations
We combine the choice data of proposers and responders in the ultimatum game, their expectations elicited in the form of subjective probability questions, and the choice data of proposers ("dictators") in a dictator game to estimate a structural model of decision making under uncertainty. We use a large and representative sample of subjects drawn from the Dutch population. Our results indicate that there is considerable heterogeneity in preferences for equity in the population. Changes in preferences have an important impact on decisions of dictators in the dictator game and responders in the ultimatum game, but a smaller impact on decisions of proposers in the ultimatum game, a result due to proposer's subjective expectations about resopnders' decisions. The model which uses subjective data on expectations has better predictive power and lower noise level than a model which assumes that players have rational expectations.Ultimatum game, inequity aversion, subjective expectations
User’s attitude to imposition of overdue fines by the library of Catholic University College of Ghana, Fiapre
The study investigated user’s attitude to the imposition of library fines at the Catholic University College. A sample size of 300 library users representing 13.8% of the 2180 users on the library’s register of borrowers as of April, 2012 was chosen through simple random sampling technique for the study . Questionnaires, observation and interviews were adopted as the data collection methods. Frequency tables, percentages and figures were also used in the data analysis. The study showed that majority of them (59.0%) have been slapped with overdue fines before. Many of the respondents cited forgetting to return the item by the due date as the main factor in the incidence of overdue fines payment. Majority of them also stated that they complied immediately they were asked to pay a fine for overdue items. Some of the recommendations made included institutionalization of grace period for defaulters, reminder messages to borrowers and establishment of ceiling for overdue fines. Keywords: Overdue fines, Library fines, Library charges, Academic library, overdue charges, Catholic University
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