388 research outputs found

    Using fishers' knowledge to explore spatial fishing patterns, perceptions of regulations, and environmental change in Alaska

    Get PDF
    Thesis (Ph.D.) University of Alaska Fairbanks, 2018In this dissertation, an interdisciplinary approach was used to examine fisher knowledge from recreational charter and subsistence fishers targeting Pacific halibut (Hippoglossus stenolepis) in Alaska. The first chapter identified biological, regulatory, social, and economic drivers of spatial fishing patterns by charter operators in two communities in Alaska. In Homer, the most frequently cited reasons for changes in the location and/or extent of fishing were changes in trip type and the price of fuel, while in Sitka, the most frequently cited reasons for spatial shifts were changes to Pacific halibut regulations and gaining experience or exploring new locations. The second chapter examined perceptions of charter operators to traditional and novel recreational fishery management tools. Results highlighted that controls on individual harvest can be perceived to have unintended consequences for charter businesses, such as effects on profitability and distance traveled. The third chapter explored variability in local ecological knowledge (LEK) of fish abundance and body size trends among charter operators and subsistence harvesters. Results suggested that peoples' perceptions of fish abundance and body size can be affected by attributes of their fishing experience and highlighted the importance of including people with different types of experience in the environment when using LEK to document environmental changes. Together, these chapters contribute to an improved understanding of the human dimensions of small-scale fisheries in Alaska, including perceptions of fishers regarding the management system and shifts in fishing behavior in response to environmental, socioeconomic, and regulatory change. Additionally, this project documented and evaluated variation in local ecological knowledge to contribute new information on data-limited marine fish species in Alaska

    Expressive cartography and the aesthetics of public visualization

    Get PDF
    Aesthetic visualization projects that incorporate users, community stakeholders, multiple modalities and technologies necessarily emphasize the way that an artistic visualization can be both an artifact and a process — a conceptualization of aesthetic visualization that is useful for thinking about visualization in general. In this paper, the authors propose the concept of expressivity as a move away from the indexical claims of visualization and instead towards an acknowledgement of the entangled nature of social, political, economic, cultural, technological and environmental actants. Through a description of the In The Air, Tonight public visualization project, the authors suggest that by making manifest the connections between these actants, a visualization project, as a form of expressive cartography, can contribute to the visibility of and engagement with important issues (e.g. homelessness) that affect society

    Comparing the Efficiency of Nursery and Direct Transplanting Methods for Restoring Endangered Corals

    Get PDF
    Restoration of plants, corals, and other sessile species often involves transplanting individuals to sites chosen for rehabilitation. Transplanted individuals are sometimes harvested directly from wild populations (direct transplanting), and sometimes propagated or cultured in a “nursery” before being transplanted (nursery outplanting). The ecological effectiveness and cost-efficiency of these methods have rarely been compared, so we performed an experiment to address this. Coral fragments, Acropora cervicornis (n = 780), were collected and assigned to one of three treatments: 1) directly transplanted to a restoration site and placed loose on the reef; 2) directly transplanted and manually attached to the reef; 3) moved to a nursery site near the restoration site for three months before being transplanted and manually attached to the reef. Treatment 1 was inefficient simply because these corals survived poorly. After 15 months, the survival and growth of corals assigned to treatments 2 and 3 was similar. The nursery method (3) was more expensive and time-consuming than direct transplanting (2), so treatment 2 yielded twice as many surviving corals per hour of work invested and three times as many survivors per dollar of set-up costs as treatment 3. The net production of live coral tissue per hour or per dollar invested was also greatest for direct-attached transplants. Cost- and time-efficiency are important considerations for practitioners seeking to maximize the area of reef rehabilitated and, in this case study, were maximized by bypassing a nursery stage

    An exploratory study on wind speed profiling of high-rise building/monument using EnviMET.

    Get PDF
    Envi-MET is a useful tool for simulating wind speed at building heights and modelling microclimatic conditions around buildings, including wind speed around buildings and other structures. Envi-MET is used in this study to simulate wind speed toward building heights. When R2 = 0.8186, relative bias is -0.0775, and RMSE is 0.2578, the agreement between Envi-MET simulation and ground observation indicates acceptable agreement. With this establishment, it was discovered that the building's height and wind speed are not the only factors causing destruction; the less friction of wind with surface features will also increase the wind speed, as shown by the results of the vertical profile wind speed in relation to the tollway building's height. At a height of 13 metres, the wind speed is 3.5 m/s. Wind circulation affects the building at this elevation, causing damage to the roof and ceiling. Buildings and structures can sustain significant damage as a result of high wind speeds. When wind speeds are high, the wind's force increases, causing pressure differences on different sides of a building or structure. The findings of this study inform relevant parties of the impact of wind on building construction and how it may influence variations in wind speed

    Effect of vegetation and waterbody on the garden city concept: an evaluation study using a newly developed city, Putrajaya, Malaysia

    Get PDF
    The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed at mitigating the effect of urban thermal modification associated with urbanisation, such as urban heat island (UHI). WRF/Noah/UCM coupled system was used to estimate the urban environment over the area and the individual thermal contributions of natural land use classes (vegetation and waterbody). A control experiment including all land use types describing the urban conditions of Putrajaya city agreed well with the observations in the region. A series of experiments was then conducted, in which vegetation and waterbody were successively replaced with an urban land use type, providing the basis for an assessment of their respective effect on urban thermal mitigation. Surface energy components, 2-m air temperature (T2m) and mixing ratio (Q2m), relative humidity (RH) and UHI intensity (UHII) showed variations for each land use class. Overall, an increase in urban surfaces caused a corresponding increase in the thermal conditions of the city. Conversely, waterbody and vegetation induced a daily reduction of 0.14 and 0.39 °C of T2m, respectively. RH, UHI and T2m also showed variations with urban fractions. A thermal reduction effect of vegetation is visible during mornings and nights, while that of water is minimally shown during daytime. However, during nights and mornings, canopy layer thermal conditions above waterbody remain relatively high, with a rather undesirable effect on the surrounding microclimate, because of its high heat capacity and thermal inertia

    Relaxation effect of abacavir on rat basilar arteries

    Get PDF
    Background The use of abacavir has been linked with increased cardiovascular risk in patients with human immunodeficiency virus infection; however, the mechanism involved remains unclear. We hypothesize that abacavir may impair endothelial function. In addition, based on the structural similarity between abacavir and adenosine, we propose that abacavir may affect vascular contractility through endogenous adenosine release or adenosine receptors in blood vessels. Methods The relaxation effect of abacavir on rat basilar arteries was studied using the myograph technique. Cyclic GMP and AMP levels were measured by immunoassay. The effects of abacavir on nucleoside transporters were studied using radiolabeled nucleoside uptake experiments. Ecto-5′ nucleotidase activity was determined by measuring the generation of inorganic phosphate using adenosine monophosphate as the substrate. Results Abacavir induced the relaxation of rat basilar arteries in a concentration-dependent manner. This relaxation was abolished when endothelium was removed. In addition, the relaxation was diminished by the nitric oxide synthase inhibitor, L-NAME, the guanylyl cyclase inhibitor, ODQ, and the protein kinase G inhibitor, KT5820. Abacavir also increased the cGMP level in rat basilar arteries. Abacavir-induced relaxation was also abolished by adenosine A2 receptor blockers. However, abacavir had no effect on ecto-5’ nucleotidase and nucleoside transporters. Short-term and long-term treatment of abacavir did not affect acetylcholine-induced relaxation in rat basilar arteries. Conclusion Abacavir induces acute endothelium-dependent relaxation of rat basilar arteries, probably through the activation of adenosine A2 receptors in endothelial cells, which subsequently leads to the release of nitric oxide, resulting in activation of the cyclic guanosine monophosphate/protein kinase G-dependent pathway in vascular smooth muscle cells. It is speculated that abacavir-induced cardiovascular risk may not be related to endothelial dysfunction as abacavir does not impair relaxation of blood vessels. The most likely explanation of increased cardiovascular risk may be increased platelet aggregation as suggested by other studies

    Land cover impacts towards thermal variation in the Kuala Lumpur City.

    Get PDF
    Physical geography and urban characteristics influence the urban climate conditions. Built-up areas, green urban parks, forest reserves, streets and terrain constitute the climatic interactions within urban areas. These have led to the variation of the urban climate condition throughout the world. Thus, in studying urban climate, the impacts of these factors are crucial to be examined. This study aims to examine the effects of six important factors, namely built-up areas, green covers, terrain elevation, building volume, surface roughness and land use type, which contribute to the variation of the urban climate condition within the Kuala Lumpur City. In this study, the effects of the six factors (urban parameters) towards the air surface temperature variation were statistically tested. Using the Weather Research and Forecasting (WRF) model and the remote sensing technique, the data needed for the analyses were extracted. The Geographical Information System (GIS) was employed as the analysis platform during the study. Based on the Spearman’s rho and Mann-Whitney U tests, it was identified that the six urban parameters and the air surface temperature variation are correlated. The further investigation conducted using the Kruskall-Wallis test has identified that only five of the urban parameters showed significant effects toward the air surface temperature variation, which are built-up areas, green covers, terrain elevation, building volume and surface roughness while the land use type was excluded. The findings of this study are very crucial as a pioneer research to integrate the urban climatic information in the urban planning decision making in tropical cities like Kuala Lumpur

    The uncharacteristic occurrence of the June 2013 biomass-burning haze event in Southeast Asia: effects of the Madden-Julian oscillation and tropical cyclone activity.

    Get PDF
    One of the worst haze events to ever hit Peninsular Malaysia occurred in June 2013 due to smoke from Riau, Central Sumatra. While biomass-burning in the region is common, the early occurrence of a haze episode of this magnitude was uncharacteristic of the seasonality of extreme fire events, which usually occur between August and October in the Maritime Continent (MC). This study aims to investigate the phenomenology of the June 2013 haze event and its underlying meteorological forcing agents. The aerosol and meteorological environment during the event is examined using the Moderate Resolution Imaging Spectroradiometer (MODIS) active fire hotspot detections and aerosol optical thickness retrievals, satellite-based precipitation retrievals, and meteorological indices. These datasets are then supported by a WRF-Chem simulation to provide a comprehensive picture of the event's meteorology and aerosol transport phenomenology. While extreme fire events are more characteristic of El Nino years, the MODIS fire count over the MC in June for the years 2001–2015 was highest in 2013 when neutral El Nino/Southern Oscillation (ENSO) conditions prevailed. Although, the mean daily precipitation for June 2013 was below average for June 2003–2015. An early active tropical cyclone (TC) season occurred in 2013, and results show that the combined induced subsidence and flow enhancement due to TC Bebinca and the dry phases of a strong Madden–Julian Oscillation (MJO) event contributed to the event intensification. Results also show that Bebinca induced a decrease in surface relative humidity of at least 10% over Riau, where fire hotspots were concentrated

    Impacts of Lateral Boundary Condition Resolution in Tropical Urban Climate Modelling for Kuala Lumpur

    Get PDF
    Choosing the best LBCs is still debated among researchers due to the errors resulted. However, several recommendations have been documented to control the errors propagated by LBCs. One of the recommendations is employing higher resolutions LBCs. In the present, many LBCs are developed with various resolutions; spatially and temporally, for many applications but no claims regarding the best LBCs for tropical climate modelling have yet been documented. Therefore, this study intends to analyse the impacts of lateral boundary condition resolution during numerical downscaling within a tropical city. This study serves as a site-specific investigation to determine the suitable LBCs for the focused study area. Two widely used LBCs with different resolutions were utilized to initiate the Weather Research and Forecasting (WRF) simulation model. The performances of the two LBCs were compared using statistical tests and analyses. The study has found that the LBC with higher resolutions excels the other LBC during inter-monsoon season. Nevertheless, it was identified that both LBCs were able to provide reliable reconstruction of the tropical climate condition of the Kuala Lumpur City as portrayed by similar results obtained. Thus, it is concluded that both LBCs can be employed in numerical downscaling for tropical urban regions similar to the Kuala Lumpur City
    corecore