79717 research outputs found
Sort by
A Comparison of Conservation Perspectives Between Scientists, Managers, and Industry in the West Coast Groundfish Fishery
Get PDFThere are several assumptions regarding the behavior and motivations of participants in fishery management that may hinder the effectiveness of the management process. In this research, we examine whether the commercial fishing industry is a homogeneous group whose decision-making is dominated by short-term economic considerations to the detriment of long-term resource conservation. Mail surveys were sent to scientists, managers, and industry members in the West Coast groundfish fishery to examine attitudes on conservation, resource abundance, and biological risk. Results demonstrate that although scientists and industry considered themselves conservation-minded, scientists were relatively critical of industry's conservation ethic. Scientists and industry differed strongly in their perception of resource abundance, but found common ground in their assessments of acceptable levels of biological and economic risks. In general, industry demonstrated considerable diversity in their responses, contradicting assumptions that industry is a monolithic group with little regard for resource conservation. Results indicate a disjuncture between industry's stated concerns and their observed participation in discarding, over-harvesting, or habitat destruction. However, this disjuncture may be the result of misaligned institutional incentives, rather than myopic values and beliefs. This evidence suggests a need to redesign institutions and property rights in order to align the interests of industry, scientists, and managers in conducting effective science and sustainably managing the West Coast groundfish fishery
Role of temperature on lipid/fatty acid composition in Pacific cod (Gadus macrocephalus) eggs and unfed larvae
Get PDFDuring early development, oviparous fish species must use finite lipid and fatty acid (FA) reserves for both catabolism and structural components. In cold environments, developing fish have the additional constraint of maintaining membrane fluidity for metabolic efficiency (homeoviscous adaptation), resulting in further demand on lower melting point FAs like n-3 polyunsaturated fatty acids (PUFAs). To examine whether marine fish embryos physiologically adapt to changing temperature environments, we incubated Pacific cod (Gadus macrocephalus) eggs at 5 temperatures (0, 2, 4, 6, and 8 °C) in the laboratory and sampled them repeatedly during development to measure changes in lipid/FA composition. Pacific cod embryos increased n-3 PUFA content during the egg stage in all temperature treatments, with the possible exception of 0 °C, where poor survival and hatch success limited our ability for continued sampling. At the beginning of the hatch cycle, free-swimming embryos shifted from lipogenesis to lipid catabolism. The rates of lipogenesis and catabolism were temperature dependent, and the distinct increase in unsaturated fatty acids at temperatures <8 °C was consistent with homeoviscous adaptation theory. However, with the possible exception of embryos at 0 °C, the relative amounts of essential fatty acids (e.g., EPA, DHA, AA) were conserved in a similar manner across incubation temperatures. Collectively, these data suggest Pacific cod are capable of homeoviscous adaptation but cannot tolerate temperatures approaching 0 °C despite their possible ability to biosynthesize PUFAs from other energetic sources
Evaluación de trampas naranjas y transparentes con éster de pera para monitorear la polilla de la manzana (Lepidoptera: Tortricidae) en huertos de manzano
No full textStudies were conducted to evaluate the use of several trap-lure combinations to improve the monitoring of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in apple, Malus domestica Bordk. The treatments involved the use of clear, orange, and white traps baited with one or more of the following attractants: the major sex pheromone component of the codling moth, (E, E)-8,10-dodecadien-1-ol (codlemone, PH); a primary volatile constituent of ripe pear, ethyl (E, Z)-2,4-decadienoate (pear ester, PE); and acetic acid (AA). The studies were conducted in an orchard treated with sex pheromone dispensers in Washington State (USA) and in four untreated orchards in the Maule Region (Chile). In Washington State, the PE+AA lures caught more females than the PE+PH lure in both the clear and orange traps. The clear traps caught more female moths than the orange traps when each trap was baited with the PE+PH lure. The two lures caught similar total numbers of moths across trap colors. The clear traps baited with PE+PH caught significantly more total moths than the orange traps baited with PE+AA. In Chile, the clear traps baited with PE+AA caught more females than the orange traps baited with PE+PH over both moth flights during two field seasons. The white traps baited with PH and the orange traps baited with PE+PH caught similar total numbers of moths in three of the four flight periods. The clear trap baited with PE+AA caught significantly fewer moths than the two treatments that included a PH lure in two of the four flight periods. These data suggest that the adoption of clear delta traps with PE+AA lures would allow growers to better track the seasonal population dynamics of female codling moths.Key words: Codlemone, Cydia pomonella, lure, monitoring, pear ester, semiochemical.Se realizaron estudios para evaluar el uso de varias combinaciones entre trampas y cebos para el monitoreo de la polilla de la manzana, Cydia pomonella (L.) (Lepidoptera: Tortricidae), en manzano Malus domestica Bordk. Los tratamientos incluyeron el uso de trampas transparentes, naranjas y blancas cebadas con uno o más de los siguientes atrayentes: (E, E)-8,10-dodecadien-l-ol (codlemona, PH), el compuesto mayoritario de la feromona sexual de la polilla de la manzana; (E, Z)-2,4-decadienoato de etilo (éster de pera, PE), un compuesto volátil constituyente del olor a pera madura; y ácido acético (AA). Los estudios fueron conducidos en un huerto tratados con dispensadores de confusión sexual en el Estado de Washington (EE.UU.) y en cuatro huertos no tratados en la Región del Maule (Chile). En el Estado de Washington los cebos PE+AA capturaron significativamente más polillas hembras que los cebos PE+PH, tanto en las trampas transparentes y naranjas. La trampa transparente capturó más polillas hembras que la trampa naranja con PE+PH. La captura total de polillas no se diferenció entre ambos cebos con distintos tipos de trampa. Las trampas delta transparentes, cebadas con PE+PH, capturaron más polillas totales que las trampas naranjas cebadas con PE+AA. En Chile, la trampa transparente cebada con PE+AA capturó significativamente más hembras que la trampa naranja cebada con PE+PH, considerando ambos vuelos y temporadas de estudio. En tres de cuatro periodos de vuelo las trampas blancas, cebadas con feromona, capturaron un número similar de polillas totales que las trampas naranjas cebadas con PE+PH. En dos de los cuatro periodos de vuelo las trampas transparentes con PE+AA capturaron significativamente menos polillas totales que los tratamientos que incluyeron cebos con PH. Estos datos sugieren que la adopción de trampas delta transparentes con cebos de PE+AA permitiría a los productores un mejor seguimiento estacional de la dinámica poblacional de las hembras de la polilla de la manzana.Palabras clave: Codlemone, Cydia pomonella, cebos, monitoreo, ester de pera, semioquímicos
Nonlocal effects in effective-medium response of nanolayered metamaterials
Get PDFThe authors analyze electromagnetic modes in multilayered nanocomposites and demonstrate that the response of a majority of realistic layered structures is strongly affected by the nonlocal effects originating from strong field oscillations across the system, and is not described by conventional effective-medium theories. They develop the analytical description of the relevant phenomena and confirm their results with numerical solutions of Maxwell equations. Finally, the authors use the developed formalism to demonstrate that multilayered plasmonic nanostructures support high-index volume modes, confined to deep subwavelength areas, opening a wide class of applications in nanoscale light management
Performance enhancement of a thermally activated cooling system using microchannel heat exchangers
Get PDFIn the current study a thermally activated cooling system that combines an ORC system with a vapor compression cooling cycle was developed and tested under laboratory conditions. This combined system
can utilize waste heat or other thermal sources such as solar and geothermal to generate power and
cooling. Hot oil with temperature up to 200 °C was used as the simulated heat source for its convenience.
Microchannel heat exchangers were used throughout the system in order to meet the performance, size
and weight challenges. Two conventional plate heat exchangers for the boiler and recuperator were also
tested inside the system for comparison purposes. Compared to the plate boiler and recuperator, the
integrated microchannel boiler/recuperator displayed significant improvement of the heat transfer
effectiveness over the range of mass flow rates examined which translates to higher conversion efficiency
and overall COP. A simplified model, used to design the microchannel recuperator, ignores the entrance
and conjugate heat transfer effects, but it appears to match well the trend of measured average heat
transfer coefficients for all cases tested. After taking into account the channel side walls, the measured
values of the average heat transfer coefficient agree also with the predicted one. Because of this relatively
conservative design approach, the actual heat transfer effectiveness for the recuperator was significantly
higher than the designed value of 85%. With the integrated microchannel boiler/recuperator, this
thermally activated cooling system was able to achieve over 5 kW of cooling and approached an overall
COP of 0.8 under laboratory conditions.This is the authors' final peer-reviewed manuscript as accepted for publication by Elsevier. Copyrighted and published by Elsevier, this article can be found at: http://www.elsevier.com/wps/find/journaldescription.cws_home/630/description#descriptio
Emerging market crises and US equity market returns
Get PDFWe find contagion effects are present in US small size portfolios during emerging market crises due to risk and liquidity concerns. Investors display flight from risk during emerging market crises, and as a result, safer larger stocks exhibit positive abnormal returns. We find little evidence of contagion in aggregate excess US market returns, indicating studies that focus on national aggregates may miss important within market dynamics during emerging market crises. The international dynamics that we document have important implications for investors, even when they may have limited global exposure.This is the authors’ post-peer review version of the final article. The final published version is copyrighted by Elsevier and can be found at:
http://www.elsevier.com/wps/find/journaldescription.cws_home/620162/description#description
Market fragility and international market crashes
Get PDFWe extend the Pukthuanthong and Roll (2009) measure of integration to provide an estimate of systemic risk within international equity markets. Our measure indicates an increasing likelihood of market crashes. The conditional probability of market crashes increases substantially following increases of our risk measure. High levels of our risk measure indicate the probability of a global crash is greater than the probability of a local crash. That is, conditional on high levels of systemic risk, the probability of a sever
Estimating Canopy Cover from Standard Forest Inventory Measurements in Western Oregon
Get PDFReliable measures of canopy cover are important in the management of public and private forests. However, direct sampling of canopy cover is both labor- and time-intensive. More efficient methods for estimating percent canopy cover could be empirically derived relationships between more readily measured stand attributes and canopy cover or, alternatively, the use of aerial photos. In this study, we compared field-based measures of percent canopy cover with estimates from aerial photography, with equations of individual tree crown width and crown overlap used in the US Forest Service Forest Vegetation Simulator (FVS) equations and with models we developed from standard stand-level forest mensuration estimates. Standard inventory estimates of cover using 1:40,000 scale aerial photos were poorly correlated with field-measured cover, especially in wet hardwood (r = 0.60) and dry hardwood (r = 0.51) stands. FVS equations underestimated cover by 17% on average at high cover levels (>70%) in wet conifer and wet hardwood stands. We also developed predictive models of canopy cover for three forest groups sampled on 884 plots by the Forest Inventory and Analysis program in western Oregon: wet conifer, wet hardwood, and dry hardwood. Predictions by the models were within 15% of measured cover for >82% of the observations. Compared with previous studies modeling canopy cover, our best predictive models included species-specific stocking equations, whereas species-invariant basal area was not an important predictor for most forest types. Accuracies of these new predictive models may be adequate for some purposes, reducing the need for direct measures of canopy cover in the field.KEYWORDS: Forest simulator, Stocking equations, Aerial photos, Crown closure, Forest inventory and analysi
Investigating the pore-scale mechanisms of microbial enhanced oil recovery
Get PDFMicrobial Enhanced Oil Recovery (MEOR) is a process where microorganisms are used for tertiary oil recovery. Numerous mechanisms have been proposed in the literature through which microorganisms facilitate the mobilization of residual oil. Herein, we focus on the MEOR mechanisms of interfacial tension reduction (via biosurfactant) and bioclogging in water-wet micromodels, using Shewanella oneidensis (MR-1) that causes bioclogging and Bacillus mojavensis (JF-2) that produces biosurfactant and causes bioclogging. Micromodels were flooded with an assortment of flooding solutions ranging from metabolically active bacteria to nutrient limited bacteria to dead inactive biomass to asses the effectiveness of the proposed MEOR mechanisms of bioclogging and biosurfactant production. Results indicate tertiary flooding of the micromodel system with biomass and biosurfactant was optimal for oil recovery due to the combined effects of bioclogging of the pore-space and interfacial tension reduction. However, biosurfactant was able to recover oil in some cases dependent on wettability. Biomass without biosurfactant that clogged the pore-space also successfully produced additional oil recovery. When analyzing residual oil blob morphology, MEOR resulted in oil blob size and radius of curvature distributions similar to those obtained by an abiotic capillary desaturation test, where flooding rate was increased post secondary recovery. Furthermore, for the capillary
number calculated during MEOR flooding with bioclogging and biosurfactant, lower residual oil saturation was measured than for the corresponding capillary number under abiotic conditions. These results suggest that bioclogging and biosurfactant MEOR is a potentially effective approach for pore morphology modification and thus flow alteration in porous media that can have a significant effect on oil recovery beyond that predicted by capillary number.Keywords: bioclogging,
micromodel,
multiphase flow,
microbial enhanced oil recovery,
water flooding,
biosurfactant,
interfacial curvatur
The Hordeum Toolbox: The Barley Coordinated Agricultural Project Genotype and Phenotype Resource
Get PDFThe use of DNA markers in public sector plant breeding is now the norm. Such markers are common across breeding programs and this commonality enables and enhances collaboration. Therefore, large collaborative research projects that measure several phenotypes across multiple environments coupled with the expanding amount of genotype data attainable with current marker technologies are on the rise and these projects demand efficient data delivery. However, development of computational tools for advanced data integration, visualization, and analysis is still a bottleneck, even though these resources have the greatest potential impact for users who are extracting and developing hypothesis-based solutions. The Hordeum Toolbox (THT) was developed as a data resource for the Barley Coordinated Agricultural Project (CAP) with the novel capability of constructing user-defined downloadable sets of phenotype and/or genotype data for downstream analysis. Internal tools in THT enable users to create clusters of a selected group of lines based on genotype data, parse pedigrees, and select germplasm based on haplotype, phenotype, and agronomic properties. The Hordeum Toolbox can be adapted to breeding programs or collaborations to assist researchers in germplasm selection, genotype data visualization, and the integration of complex data sets for statistical analysisThis is the publisher’s final pdf. The published article is copyrighted by the Crop Science Society of America and can be found at: https://www.crops.org/publications/tp