370 research outputs found

    Fielding Ditch Pipeline Computer Simulation Study

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    The Fielding Ditch Company Pipeline is almost 3 miles long and supplies irrigation water under low pressure to adjacent fields through 33 turnouts along its length. The 24-inch non-reinforced concrete pipeline began to experience repeated structural failures soon after it was placed in operation. This study was done for the Soil Conservation Service by the Utah Water Research Laboratory to gather field data on the pipeline operating characteristics, to analyze the hydraulic transients in the pipeline with the help of a computer simulation model, and to suggest modification to protect the pipeline from future failures caused by transient pressures. Following a description of the pipeline system, the concepts and principles of unsteady flow in pipelines are summarized. Then the general equations for transient flow are presented followed by a summary of their solution using numerical methods. Under the field verification data collection program, instruments and recorders were set up at four locations along the pipeline. Pressure and flow measurements during both steady and unsteady flows were recorded to obtain data on the operating characteristics of the pipeline. These field data as well as preliminary analysis indicate that moderate closure times of valves could generate pressure waves which could overstress the non-reinforced concrete pipe. The field data also provided a way to verify that the computer simulation model could truly represent the behavior of the actual pipeline system. The field data also shoed the pressure wave speed to be about 1170 feet per second rather than 3640 feet per second predicted by the wave speed equations. This significant change in wave speed was attributed to the effect of free air trapped in pipe joints and high spots in the pipeline. Seven increasingly complex computer models were developed to represent the pipeline. The first was a simple basic water hammer program for a pipe with a reservoir upstream and a valve at the downstream end which could close instantly. Later programs added the effects of air pockets along the pipeline, damping or dissipation at the air pockets, gradual closure of the downstream valve, gradual closure of a valve at an interior point, simultaneous closure of two valves and provision for protective standpipes at any or all interior valve locations. Comparisons of the final programs with field data showed the system to be adequately represented. The computer programs were then used to compare the effectiveness of various proposed protective modifications to the pipeline. Modifications considered but not recommended included requiring a longer valve closure time (not fail safe), installation of pressure relief valves (not reliable), and installation of air chambers at each valve (not economical). The recommended pipeline modification was to install eleven 18-inch pressure relief standpipes at selected interior turnout locations and one 36-inch standpipe at the downstream end. The study showed that the spillage at the standpipes to an acceptable amount. Smaller 2- or 3-inch diameter standpipes should also be installed at all other turnouts to release trapped air and to serve as indicators (to nearby valve operators) or too rapid closure of the valves

    Hydrologic Evaluation of the Coastal Belt Water Project Sarir and Tazerbo Well Fields, Libya

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    Executive Summary: The basic purpose of this study was to conduct a finite-element computer model and give an dindependent appraisal of the reliability of the groundwater supply for the proposed Coastal Belt Water Project (CBWP_ Well Fields at Sarir and Tazerbo. There is no doubt that ample quantities of groundwater of acceptable quality occur at the sites selected for these well fields for the estimated 50-year life of the project and longer. Of major concern is the predicted drawdown of wells and total pumping lifts throughout the 50-year period. Excessive drawdowns could cause operating costs to become prohibitibely expensive. Average drawdown in wells not including well-field interference and hydraulic friction losses at the CBWP Well Field at Sarir is expected to be only about 30 m at the end of 50 years, but the static water level is relatively deep (56 m) which makes the total pumping lift fairly high when well-field interference and other losses are added. This optimistic estimate of drawdown is based upon computer analysis for almost 7 years of pumping history of the existing Sarir South agricultural well field nearby, where the subsurface geology is believed to be quite similar to that at the propsed CBWP Well Field at Sarir. The average dpumping lift, which includes many other factors besides aquifer drawdown, is estimated to be about 142 m. at the end of the 50-year pumping period at Sarir and should average about 136 m during the 50 years. Interference from pumpage at the existing agricultural well fields at Sarir may be responsible for about 10 m of this predicted pumping lift. Drawdown at Tazerbo is predicted to be about 90 m. at the end of 50 years, but the static water level is only about 9 m. there. Consequently its average pumping lift should be about 133 m at the end of the 50-year pumping period and should average about 118 m during the 50 years. no appreciable interference from nearby well fields is expected in the Tazerbo area based upon presently known conditions. Significatn reductions in pumping lifts at Tazerbo and in water-collection network costs at Sarir are possible by improved well field layout and well design. Suggested inprovements and estimated cost savings are presented in detail in Appendix A (especially see well-field design comparisons of Tables A-1 and A-4)

    The genus <i>Elaphomyces </i>(<i>Ascomycota</i>, <i>Eurotiales</i>):a ribosomal DNA-based phylogeny and revised systematics of European 'deer truffles'

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    Elaphomyces (‘deer truffles’) is one of the most important ectomycorrhizal fungal genera in temperate and subarctic forest ecosystems, but also one of the least documented in public databases. The current systematics are mainly based on macromorphology, and is not significantly different from that proposed by Vittadini (1831). Within the 49 species recognised worldwide, 23 were originally described from Europe and 17 of these were described before the 20th century. Moreover, very recent phylogenetic treatments of the genus are mainly based on a few extra-European species and most common European species are still poorly documented. Based on an extensive taxonomic sampling mainly made in the biogeographically rich Cantabrian area (Spain), complemented with collections from France, Greece, Italy, Norway, Portugal and Sweden, all currently recognized species in Europe have been sequenced at the ITS and 28S of the rDNA. Combined phylogenetic analyses yielded molecular support to sections Elaphomyces and Ceratogaster (here emended), while a third, basal lineage encompasses the sections Malacodermei and Ascoscleroderma as well as the tropical genus Pseudotulostoma. Species limits are discussed and some taxa formerly proposed as genuine species based on morphology and biogeography are re-evaluated as varieties or forms. Spore size and ornamentation, features of the peridial surface, structure of the peridium, and the presence of mycelium patches attached to the peridial surface emerge as the most significant systematic characters. Four new species: E. barrioi, E. quercicola, E. roseolus and E. violaceoniger, one new variety: E. papillatus var. sulphureopallidus, and two new forms: E. granulatus forma pallidosporus and E. anthracinus forma talosporus are introduced, as well as four new combinations in the genus: E. muricatus var. reticulatus, E. muricatus var. variegatus, E. papillatus var. striatosporus and E. morettii var. cantabricus. Lectotypes and epitypes are designated for most recognised species. For systematic purposes, new infrageneric taxa are introduced: E. sect. Ascoscleroderma stat. nov., E. subsect. Sclerodermei stat. nov., E. subsect. Maculati subsect. nov., E. subsect. Muricati subsect. nov., and E. subsect. Papillati subsect. nov. Lastly, E. laevigatus, E. sapidus, E. sulphureopallidus and E. trappei are excluded from the genus and referred to Rhizopogon roseolus, Astraeus sapidus comb. nov., Astraeus hygrometricus and Terfezia trappei comb. nov. (syn.: Terfezia cistophila), respectively

    Expression of a barley cystatin gene in maize enhances resistance against phytophagous mites by altering their cysteine-proteases

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    Phytocystatins are inhibitors of cysteine-proteases from plants putatively involved in plant defence based on their capability of inhibit heterologous enzymes. We have previously characterised the whole cystatin gene family members from barley (HvCPI-1 to HvCPI-13). The aim of this study was to assess the effects of barley cystatins on two phytophagous spider mites, Tetranychus urticae and Brevipalpus chilensis. The determination of proteolytic activity profile in both mite species showed the presence of the cysteine-proteases, putative targets of cystatins, among other enzymatic activities. All barley cystatins, except HvCPI-1 and HvCPI-7, inhibited in vitro mite cathepsin L- and/or cathepsin B-like activities, HvCPI-6 being the strongest inhibitor for both mite species. Transgenic maize plants expressing HvCPI-6 protein were generated and the functional integrity of the cystatin transgene was confirmed by in vitro inhibitory effect observed against T. urticae and B. chilensis protein extracts. Feeding experiments impaired on transgenic lines performed with T. urticae impaired mite development and reproductive performance. Besides, a significant reduction of cathepsin L-like and/or cathepsin B-like activities was observed when the spider mite fed on maize plants expressing HvCPI-6 cystatin. These findings reveal the potential of barley cystatins as acaricide proteins to protect plants against two important mite pests

    Ambulatory dispersal in Tetranychus urticae: an artificial selection experiment on propensity to disperse yields no response

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    Dispersal to new hosts is an important process for an invasive herbivore, such as the two-spotted spider mite. A recent study, using artificial selection experiments, has suggested that genetic variation and genetic trade-offs are present for propensity to disperse in this species. However, due to the experimental setup alternative explanations for the response to selection could not be ruled out. Using an altered setup, we investigated whether the propensity for ambulatory dispersal differs genetically between individuals and whether genetic correlations with life-history traits exist. Upward and downward selection on propensity to leave the colony was performed for seven generations in four replicate artificial selection experiments and the results were compared to control lines. No consistent responses to selection were found and no significant effect on life-history traits (oviposition rate, juvenile survival, development rate and number of adult offspring) or sex ratio was present across the replicates. The data suggest that our base population of spider mites harbours at best a low amount of additive genetic variation for this behaviour

    Omalizumab may decrease IgE synthesis by targeting membrane IgE+ human B cells

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    Omalizumab, is a humanized anti-IgE monoclonal antibody used to treat allergic asthma. Decreased serum IgE levels, lower eosinophil and B cell counts have been noted as a result of treatment. In vitro studies and animal models support the hypothesis that omalizumab inhibits IgE synthesis by B cells and causes elimination of IgE-expressing cells either by induction of apoptosis or induction of anergy or tolerance. METHODS: We examined the influence of omalizumab on human tonsillar B cell survival and on the genes involved in IgE synthesis. Tonsillar B cells were stimulated with IL-4 plus anti-CD40 antibody to induce class switch recombination to IgE production in the presence or absence of omalizumab. Cell viability was assessed and RNA extracted to examine specific genes involved in IgE synthesis. CONCLUSIONS: We found that omalizumab reduced viable cell numbers but this was not through induction of apoptosis. IL-4R and germline Cϵ mRNA levels were decreased as well as the number of membrane IgE+ cells in B cells treated with omalizumab. These data suggest that omalizumab may decrease IgE synthesis by human B cells by specifically targeting membrane IgE-bearing B cells and inducing a state of anergy

    Comparative Demography of the Spider Mite, Oligonychus afrasiaticus, on four Date Palm Varieties in Southwestern Tunisia

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    The date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), is a serious pest of palm date fruits. Life cycle, fecundity, and longevity of this mite were studied on fruits of four date palms, Phoenix dactylifera L. (Arecales: Arecaceae)(varieties: Deglet Noor, Alig, Kentichi, and Besser), under laboratory conditions at 27 = 1 °C, 60 ± 10% RH. Total development time of immature female was shorter on Deglet Noor fruits than on the other cultivars. O. afrasiaticus on Deglet Noor had the highest total fecundity per female, while low fecundity values occurred on Besser. The comparison of intrinsic rates of natural increase (rm), net reproductive rates (Ro), and the survival rates of immature stage of O. afrasiaticus on the host plants suggests that O. afrasiaticus performs better on Deglet Noor fruits. The mite feeding on Alig showed the lowest intrinsic rate of natural population increase (rm = 0.103 day 1). The estimation of difference in susceptibility of cultivars to O. afrasiaticus is crucial for developing efficient pest control programs. Indeed, less susceptible cultivars can either be left unsprayed or sprayed at low threshold
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