383 research outputs found

    Trapping Male Melon Flies, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), Using Mixtures of Zingerone and Cue-Lure in the Field

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    The males of many fruit flies (Diptera: Tephritidae) are strongly attracted to, and feed upon, a few natural compounds (and their synthetic analogs; commonly referred to as “lures”). Zingerone is a lure that has garnered recent attention for its use as an attractant for ecological surveys and pest management of select fruit flies. We investigated the attraction of male melon flies, Zeugodacus cucurbitae (Coquillett), to zingerone and mixtures of zingerone and cue-lure (the typical lure for this species) at a commercial farm on Oahu, Hawaii. Our findings indicate that zingerone and mixtures of zingerone and cue-lure are less attractive than cue-lure alone to male melon flies in the field, and the number of captured flies is positively and linearly correlated to the quantity of cue-lure in traps

    Infertility associated with the duration of luteal phase in postpartum cows

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    After first postpartum ovulation most cows have a short luteal phase due to a premature secretion of PGF2 from the uterus. Pregnancy rate in estrous cycles with short luteal phases is essentially nil. The lack of exposure of the uterus to P4 and estrogen prior to first postpartum ovulation decreases the concentration of P4 receptors and up regulates oxytocin receptors. The inadequate number of P4 receptors and presence of endometrial oxytocin receptors earlier in cows with short than normal luteal phases allows premature release of PGF2a and the resultant regression of the CL. During luteolysis, uterine and luteal PGF2a cause death of the embryos mainly during the transition from morula to blastocyst when the embryos are more susceptible to embryotoxic effect

    Computational and Experimental Study of Supersonic Nozzle Flow and Shock Interactions

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    This study focused on the capability of NASA Tetrahedral Unstructured Software System's CFD code USM3D capability to predict the interaction between a shock and supersonic plume flow. Previous studies, published in 2004, 2009 and 2013, investigated USM3D's supersonic plume flow results versus historical experimental data. This current study builds on that research by utilizing the best practices from the early papers for properly capturing the plume flow and then adding a wedge acting as a shock generator. This computational study is in conjunction with experimental tests conducted at the Glenn Research Center 1'x1' Supersonic Wind Tunnel. The comparison of the computational and experimental data shows good agreement for location and strength of the shocks although there are vertical shifts between the data sets that may be do to the measurement technique

    Microbial Iron Cycling in Acidic Geothermal Springs of Yellowstone National Park: Integrating Molecular Surveys, Geochemical Processes, and Isolation of Novel Fe-Active Microorganisms

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    Geochemical, molecular, and physiological analyses of microbial isolates were combined to study the geomicrobiology of acidic iron oxide mats in Yellowstone National Park. Nineteen sampling locations from 11 geothermal springs were studied ranging in temperature from 53 to 88°C and pH 2.4 to 3.6. All iron oxide mats exhibited high diversity of crenarchaeal sequences from the Sulfolobales, Thermoproteales, and Desulfurococcales. The predominant Sulfolobales sequences were highly similar to Metallosphaera yellowstonensis str. MK1, previously isolated from one of these sites. Other groups of archaea were consistently associated with different types of iron oxide mats, including undescribed members of the phyla Thaumarchaeota and Euryarchaeota. Bacterial sequences were dominated by relatives of Hydrogenobaculum spp. above 65–70°C, but increased in diversity below 60°C. Cultivation of relevant iron-oxidizing and iron-reducing microbial isolates included Sulfolobus str. MK3, Sulfobacillus str. MK2, Acidicaldus str. MK6, and a new candidate genus in the Sulfolobales referred to as Sulfolobales str. MK5. Strains MK3 and MK5 are capable of oxidizing ferrous iron autotrophically, while strain MK2 oxidizes iron mixotrophically. Similar rates of iron oxidation were measured for M. yellowstonensis str. MK1 and Sulfolobales str. MK5. Biomineralized phases of ferric iron varied among cultures and field sites, and included ferric oxyhydroxides, K-jarosite, goethite, hematite, and scorodite depending on geochemical conditions. Strains MK5 and MK6 are capable of reducing ferric iron under anaerobic conditions with complex carbon sources. The combination of geochemical and molecular data as well as physiological observations of isolates suggests that the community structure of acidic Fe mats is linked with Fe cycling across temperatures ranging from 53 to 88°C

    In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study

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    <p>Abstract</p> <p>Background</p> <p>Three methods were developed for the application of stoichiometry-based network analysis approaches including elementary mode analysis to the study of mass and energy flows in microbial communities. Each has distinct advantages and disadvantages suitable for analyzing systems with different degrees of complexity and <it>a priori </it>knowledge. These approaches were tested and compared using data from the thermophilic, phototrophic mat communities from Octopus and Mushroom Springs in Yellowstone National Park (USA). The models were based on three distinct microbial guilds: oxygenic phototrophs, filamentous anoxygenic phototrophs, and sulfate-reducing bacteria. Two phases, day and night, were modeled to account for differences in the sources of mass and energy and the routes available for their exchange.</p> <p>Results</p> <p>The <it>in silico </it>models were used to explore fundamental questions in ecology including the prediction of and explanation for measured relative abundances of primary producers in the mat, theoretical tradeoffs between overall productivity and the generation of toxic by-products, and the relative robustness of various guild interactions.</p> <p>Conclusion</p> <p>The three modeling approaches represent a flexible toolbox for creating cellular metabolic networks to study microbial communities on scales ranging from cells to ecosystems. A comparison of the three methods highlights considerations for selecting the one most appropriate for a given microbial system. For instance, communities represented only by metagenomic data can be modeled using the pooled method which analyzes a community's total metabolic potential without attempting to partition enzymes to different organisms. Systems with extensive <it>a priori </it>information on microbial guilds can be represented using the compartmentalized technique, employing distinct control volumes to separate guild-appropriate enzymes and metabolites. If the complexity of a compartmentalized network creates an unacceptable computational burden, the nested analysis approach permits greater scalability at the cost of more user intervention through multiple rounds of pathway analysis.</p

    Drivers of success in implementing sustainable tourism policies in urban areas

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    The existing literature in the field of sustainable tourism highlights a number of barriers that impede the implementation of policies in this area. Yet, not many studies have so far considered the factors that would contribute to putting this concept into practice, and few address the case of urban areas. The concept of sustainability has only received limited attention in urban tourism research, even though large cities are recognised as one of the most important tourist destinations that attract vast numbers of visitors. Adopting a case study approach, this paper discusses a number of drivers of success identified by policy-makers in London to contribute to the implementation of sustainable tourisms policies at the local level, and briefly looks at the relationship between these drivers and the constraints perceived by the respondents to hinder the implementation of such policies in practice. These findings may help policy-makers in other large cities to successfully develop and implement policies towards sustainable development of tourism in their area

    Photosynthetic adaptation and acclimation to exploit seasonal periods of direct irradiance in three temperate, deciduous-forest herbs

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    1.  We evaluated the potential for three species of deciduous-forest herbs to exploit seasonal periods of direct irradiance. In particular, we investigated the importance of photosynthetic acclimation as a mechanism for shade-tolerant herbs to utilize direct light reaching the forest floor before canopy expansion in the spring and after canopy leaf drop in the autumn. 2.  We measured the photosynthetic and growth characteristics of three co-occurring herbs of a northern hardwood forest: the spring ephemeral Allium tricoccum Ait., the summer-green Viola pubescens Ait., and the semi-evergreen Tiarella cordifolia L. 3.  Leaf CO 2 exchange, leaf mass per area, and leaf biochemistry differed among species and seasonally within species to match the changing light environment below the forest canopy. From spring to summer, as irradiance dropped with the expansion of the overstorey canopy, Viola leaves exhibited reduction of both photosynthetic capacity and light compensation point. Weaker acclimation of less magnitude occurred in Tiarella leaves over the spring–summer light transition; this was followed by further acclimation to the stronger autumn irradiance. 4.   Viola ’s greater range of photosynthetic acclimation was associated with shifts in allocation between Rubisco and chlorophyll, as well as changes in total leaf nitrogen (N) concentration and leaf mass per area (LMA). In contrast, Tiarella ’s narrow range of acclimation was associated solely with changes in allocation to Rubisco versus chlorophyll, with no changes in total leaf N or LMA. 5.  Seasonal changes in leaf chemistry and structure in Viola suggest a stepwise ontogeny whereby individual leaves are able to function as ‘sun leaves’ for 3–5 weeks in the spring, and then as ‘shade leaves’ for up to 3 months in the summer. 6.  Whole-plant biomass accumulation showed that all three species accumulated most of their annual biomass increment during periods of direct irradiance. These results demonstrate the importance of brief seasonal periods of strong irradiance to the growth of deciduous forest herbs, even shade-tolerant, summer and evergreen species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75494/1/j.0269-8463.2001.00584.x.pd

    Strategic Planning for Local Tourism Destinations: An Analysis of Tourism

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    This paper reports on a study of the planning practices of local tourism destinations. The tourism plans of 30 local tourism destinations in Queensland, Australia were analyzed to determine the extent to which sustainability principles, namely strategic planning and stakeholder participation, were integrated into the planning process. Utilizing a tourism planning process evaluation instrument developed by Simpson (2001), it was found that local tourism destinations are not integrating sustainability principles in their planning processes
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