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排序方式: 共有103条查询结果,搜索用时 312 毫秒
1.
In 1999 the Arizona Department of Transportation (ADOT) began improvements along the State Route 85 (SR85) corridor between Gila Bend and Interstate 10 (I-10). At the time SR85 was a two-lane highway that carried a large volume of truck traffic between Interstate 8 near Gila Bend and Phoenix. The SR85 roadway improvements project is broken into phases. The first phase includes the construction of frontage roads and using these roads as a divided highway. Once the divided highway is completed, the final freeway cross section will be constructed between the frontage roads. The project impacted existing irrigation facilities for three irrigation districts located between the Gila River and I-10; the Arlington Canal Company, Buckeye Water Conservation and Drainage District (BWCDD) and Roosevelt Irrigation District (RID). The roadway improvements impact three main canals, turnouts from the main canal, main canal check structures, delivery structures, laterals, groundwater wells and tailwater collection systems. Three miles of irrigation facilities relocations were completed in various phases between 1999 and 2009. Total construction cost as of May 2009 is about $9.4 million. ADOT is currently working on 30% design plans for the main line between the Gila River and Broadway Road. The irrigation districts are coordinating with ADOT regarding the impacts to the irrigation facilities. In this paper we present the institutional and functional constraints to infrastructure modernization in an urbanizing area with historic irrigated agriculture. This process was complicated by the need to continue to operate the irrigation delivery facilities on an almost year-round basis.  相似文献   
2.
Anemonefishes dominate the marine ornamental aquaculture production and coloration plays an important role in market price of the product. This study examined the effect of dietary esterified astaxanthin concentration and duration on skin coloration in spinecheek anemonefish, Premnas biaculeatus. The chromatophore physiology parameters examined were color, density, and diameter of carotenoid granules. Juveniles of 30 days post hatch (d.p.h.) were fed diets consisting of 23, 214, or 2350 ppm esterified astaxanthin for 115 d and the fish were sampled at 45, 120, and 145 d.p.h. Hue was significantly reduced with increasing time and astaxanthin concentration. Saturation fluctuated over time while luminosity was only affected by time. Carotenoid granule density was similar across the treatments: approximately 0.3 granules/µm2. Significant difference in carotenoid granule size was detected, with larger diameters at the higher astaxanthin treatment. Carotenoid granules showed significantly lower hues, higher saturation, and lower luminosity values for the higher astaxanthin concentration diets. This is indicative of higher concentration of carotenoids in the granules. Diets explicitly imparted different coloration in P. biaculeatus and the manifested color differences in the fish are result of increased carotenoid granule size and increased carotenoid concentration within granules. Astaxanthin concentration of 214 ppm imparts adequate coloration for high market value.  相似文献   
3.
An experiment was conducted to determine how an E. coil challenge and dietary clays affect the intestinal barrier of pigs. Two groups of 32 pigs (initial BW: 6.9 ± 1.0 kg) were distributed in a 2 x 4 factorial arrangement of a randomized complete block design (2 challenge treatments: sham or E. coil, and 4 dietary treatments: control, 0.3% smectite A, 0.3% smectite B and 0.3% zeolite), with 8 replicates total. Diarrhea score, growth performance, goblet cell size and number, bacterial translocation from intestinal lumen to lymph nodes, intestinal morphology, and relative amounts of sulfo and sialo mucins were measured. The E. coli challenge reduced performance, increased goblet cell size and number in the ileum, increased bacterial translocation from the intestinal lumen to the lymph nodes, and increased ileal crypt depth. One of the clays (smectite A) tended to increase goblet cell size in ileum, which may indicate enhanced protection. In conclusion, E. coli infection degrades intestinal barrier integrity but smectite A may enhance it.  相似文献   
4.
Banana and plantain are among the most important food crops in developing countries but production is threatened by increasing virulent forms of Fusarium oxysporum f. sp. cubense. Chemical control is not economically effective and,therefore, breeding programs are necessary. Traditional field studies of new genotype resistance to this disease are time-consuming and destructive. Therefore,we developed a rapid and non-destructive procedure to differentiate field-grown banana resistant from susceptible clones. This procedure implicates application of culture filtrates of Fusarium oxysporum f. sp. cubense race 1 onto banana leaves. The relationship between duration of the fungal in vitro incubation, and the fungal culture fresh mass, the culture filtrate absorbency, and the Gross Michel (susceptible cultivar)leaf lesion area (after application of the culture filtrate) were similar and at 24day-incubation the highest values of the recorded indicators were observed. A comparison between Gross Michel and FHIA-01(resistant) was also performed. The most relevant differences between cultivars were observed at 48 hours after application of the culture filtrate, and in the middle-aged leaves. The position of the culture filtrate application in the leaf limb (distal, middle, proximal) was not determinant. A wider comparison among banana cultivars confirmed previous results informed by other researchers using different systems to study this plant-fungus interaction. Such a confirmation validates the effectiveness of the procedure described here to select rapid and non-destructively banana resistance to this disease at field level. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
5.
Microwave spectroscopy experiments have been performed on two quantum levels of a macroscopic superconducting loop with three Josephson junctions. Level repulsion of the ground state and first excited state is found where two classical persistent-current states with opposite polarity are degenerate, indicating symmetric and antisymmetric quantum superpositions of macroscopic states. The two classical states have persistent currents of 0.5 microampere and correspond to the center-of-mass motion of millions of Cooper pairs.  相似文献   
6.
Understanding the suppression of ferroelectricity in perovskite thin films is a fundamental issue that has remained unresolved for decades. We report a synchrotron x-ray study of lead titanate as a function of temperature and film thickness for films as thin as a single unit cell. At room temperature, the ferroelectric phase is stable for thicknesses down to 3 unit cells (1.2 nanometers). Our results imply that no thickness limit is imposed on practical devices by an intrinsic ferroelectric size effect.  相似文献   
7.
OBJECTIVE: To establish whether hydroxyapatite (HA) coatings applied to metal total-hip-replacement components increased synovitis in the coxofemoral joint of dogs. Study Design-An in vivo research trial and histologic study. ANIMALS: Twenty-three large, mixed-breed dogs. METHODS: Arthroplasty components were implanted with HA on neither stem nor cup, or with HA applied to either the femoral component or with both stem and cup having HA applied in 23 dogs. Synovial inflammation was scored 3, 6, and 12 months after surgery. Synovial membrane thickness; polyethylene particulate load; fibrin exudate; membrane edema; mitotic index; giant-cell, mononuclear histiocyte, lymphocyte, and polymorph number; and collagen degeneration were scored and statistical analyses performed. RESULTS: Operated-side synovial thickness was greatly increased relative to control. Fibrin deposition, intramembranous edema, and collagen degeneration were similar within each time interval among the various component groups. The majority of inflammatory scores among the groups were unchanged. In this 12-month study, the presence of HA coatings appear not to have a marked impact on the development of synovial inflammation. CONCLUSIONS: HA-coated components do appear to contribute somewhat to the inflammatory load within the periprosthetic environment, but this effect is not marked. CLINICAL RELEVANCE: The major advantage of HA addition to arthroplasty components is enhanced osteoconductivity around metallic surfaces. The slight increase in particulate load seen in the presence of HA coatings may contribute to the development of aseptic loosening of arthroplasty components, but is unlikely to be the major causative factor.  相似文献   
8.
A plant breeding program is a long-term investment. Therefore, periodic assessment of the effectiveness of a breeding strategy is essential to maximize genetic gains per unit of time and resource invested. In this work, we assessed the effectiveness of the early-generation testing (EGT) approach used in the upland rice (Oryza sativa L.) breeding program at Embrapa (Brazilian Agricultural Research Corporation), Brazil, estimating the genetic progress achieved for three traits in two distinct phases, spanning 15 years. In the first phase (from 2003 to 2010), it was used the bulk method within F3 progenies with prior testing of F2 crosses, while in the second phase (from 2010 to 2017), it was used the bulk method within F2 progenies. The dataset comprised 70 yield trials, involving 1884 F3:5 progenies (phase I) and 925 F2:4 progenies (phase II) from an elite population, and 10 check cultivars, evaluated for grain yield (GY), plant height (PH) and days to flowering (DTF). For estimating the genetic gain, we adapted a generalized linear regression method to compute bi-segmented linear regression coefficients. Desirable genetic gains were achieved only for GY in both phases of the breeding program, with 78.75 kg ha?1 year?1 (2.68%) in the first phase, and 53.78 kg ha?1 year?1 (1.54%) in the second phase. These results show the effectiveness of EGT, especially via bulk method within F3 progenies with prior testing of F2 crosses, applied to upland rice breeding. Some refinements are discussed in the method to make it more cost-effective and more efficient in achieving genetic gains.  相似文献   
9.
The parasitoid complex of the Asian chestnut gall wasp Drycosmus kuriphilus Yasumatsu was studied in Calabria (Italy). A total of 14 different species of parasitoids were collected, of which three are recorded on the Asian gall wasp for the first time. The composition of the parasitoid complex collected in Calabria was compared with that reported from Italy and from Europe. The altitude of the sites of collection seemed to have an effect on the distribution and abundance of the single species of parasitoids.  相似文献   
10.
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