430 research outputs found

    The activation and deactivation of platinum/rhodium catalysts for ammonia oxidation

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    Managing Scarce Resources in Training Projects

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    Every training organization has a limited amount of people, time and/or money available to complete a project, and this limited resource availability undoubtedly will affect the scope and success of projects the organization undertakes. Busby and Goldsmith discuss the knowledge and skills thing in the instructional design field will need to successfully address these circumstances. The authors begin the chapter by defining what they mean by resources and resource scarcity, and then go on to describe how resource availability and the scope of a project affect one another. They then discuss such basic economic concepts as supply and demand and the economic cycle, factors that have a profound influence on resource availability. The authors then conclude by providing strategies a training manager can adopt to address the problems presented by resource scarcity

    Predictors of poor function in RA based on two prospective UK inception cohorts. Do comorbidities matter?

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    © The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Rheumatology. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/)Objectives. Evidence suggests that factors beyond disease activity associate with functional disability in RA. The primary study objective was to explore associations between comorbidities, sociodemographic factors and functional outcomes at five and 10 years.  Methods. RA patients from two UK prospective cohorts were grouped into low (<1.5) and high (1.5) five- and 10-year health assessment questionnaire (HAQ) score. Clinical variables (e.g. disease activity, rheumatoid nodules, erosions) and sociodemographic factors (e.g. ethnicity, deprivation) were recorded at baseline and yearly thereafter. Comorbidity was measured using the Rheumatic Diseases Comorbidity Index (RDCI). Binary logistic regression models were fitted using multiple imputation.  Results. In total, 2701 RA patients were recruited (mean age 56.1 years, 66.9% female). A total of 1718 (63.4%) had five-year and 820 (30.4%) 10-year follow-up data. In multivariable analysis, no association was found between RDCI and HAQ 1.5 at five or 10 years. Sociodemographic factors (increased age at disease onset, female gender, minority ethnicity) were associated with higher odds of HAQ 1.5 at five and 10 years, with worse deprivation additionally associated with HAQ 1.5 at 10 years (OR 0.79, 95% CI: 0.69, 0.90).  Conclusion. Comorbidities at baseline have not been found to be associated with worse RA functional outcome in the long-term. On the other hand, sociodemographic factors, independently of disease measures, are associated with worse functional outcome in RA at five and 10 years, in models adjusting for comorbidity burden. Tailoring management interventions according to not only clinical disease parameters but also patient sociodemographic factors may improve long-term outcomes including functional disability.Peer reviewe

    Disturbance, Pollinator Predictability, and Pollination Success Among Costa Rican Cloud Forest Plants

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    Cloud forest at Monteverde, Costa Rica experiences frequent natural disturbance. To determine whether species interactions vary spatially due to physical heterogeneity produced by disturbance, we examined relationships between 22 plant species and 11 nectar—feeding bird species in 14 study plots distributed among three patch types: larger landslide—like gaps (hand—cleared areas along a trail), small gaps (formed by recent treefalls), and understory of closed—canopy forest. Species we describe here flowered in two or three patch types. The aspects of pollination we examined varied little with patch type. Mean frequency of pollinator visits varied with patch type in a few plant species but not in most, and there was no significant trend across species. Pollen loads carried by 314 mist—netted hummingbirds did not vary significantly with patch type, either in total number of grains or number of species represented. Cumulative pollen loads that hummingbirds deposited on stigmas of two species of Acanthaceae (Razisea spicata and Hansteinia blepharorachis) did not vary consistently with patch type, except that Hansteinia flowers in treefall gaps received fewer heterospecific pollen grains than flowers in the other two patch types. Frequency of fruit set varied significantly with patch type in three of the four species examined, but the direction of variation in one of these was opposite to the direction of the other two. The absolute frequency with which flowers were pierced by nectar—robbing hummingbirds did not vary significantly with patch type, although the frequency of piercing relative to legitimate pollinator visits did increase in the large gaps. We attribute the latter result to aggregation of the hummingbird Eupherusa eximia, a chronic nectar robber, at dense clumps of long—flowered plant species that occurred in large gaps. Only one feature we examined suggested that patch type might directly affect the nature of species interactions: in two different analyses, the level of variation in frequency of hummingbird visits to flowers declined from large gaps to small gaps to forest. Results suggest that, unless the disturbance initiating a patch is unusually severe or widespread, interactions between the plants and hummingbirds examined are insensitive to patch type. Such species, existing in naturally dynamic forests throughout their recent evolutionary histories, presumably have become accommodated to frequent small—scale disturbance. Results also suggest that those habitat—related contrasts in plant reproductive traits and plant—pollinator interactions documented in other studies, which compare habitats initiated by anthropogenic disturbances with undisturbed patches, may be artifacts to some extent. Anthropogenically generated disturbance mosaics may promote the spread of species whose reproductive traits evolved under very different circumstances from mosaics generated by natural disturbances

    Winter grazing of corn residues: Effects on soil properties and subsequent crop yields from a corn-soybean crop rotation

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    Corn residues could be a good resource for winter cattle grazing. The study investigates whether winter grazing causes soil compaction and yield reduction in crops that are planted following grazing

    Effects of Corn Crop Residue Grazing on Soil Physical Properties and Subsequent Soybean Production in a Corn–Soybean Crop Rotation

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    For three years beginning in 1999, a 96-acre field near Atlantic, Iowa was used to study the effects of corn residue grazing by beef cows on soil characteristics and soybean yields in subsequent years. Each winter, cows were allowed to graze corn crop residues inside selected paddocks in four sub-fields over five monthly periods. To compare the effects of grazing, one paddock was left as an ungrazed control. At the end of grazing in the spring, soil bulk density, moisture content, and penetration resistance were measured inside and 15 ft outside twelve grazing exclosures in each paddock. Soil surface roughness, texture, and type were also measured in twelve locations in each paddock. Corn crop residues were collected for yield, cover, and composition at the initiation, middle and termination of grazing. Precipitation and soil temperature also were recorded throughout the grazing season. Each following year, soybeans were planted in replicated subfields with disking or no tillage and harvested using a combine equipped with a yield monitor and global positioning system (GPS). Cattle grazing corn crop residue has shown no effect on soil bulk density, but there has been a measurable effect on penetration resistance in paddocks grazed in October and November (P\u3c 0.05). There is an increase in soil surface roughness during certain periods of cattle grazing where 75% of the variation can be contributed to increase in the amount of time soil temperature is above freezing. Cattle grazing had no effect on soybean plant population. However, 36 and 38% of the variation in soybean yield can be attributed to penetration resistance and soil surface roughness

    Evaluation of fixed sources of variation and estimation of genetic parameters for incidence of bovine respiratory disease in preweaned calves and feedlot cattle

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    The primary objective of this study was to estimate variance components and heritability of bovine respiratory disease (BRD) incidence in beef calves before weaning and during the finishing phase. The second objective was to investigate the impact of BRD incidence and treatment frequency on performance and carcass traits. Bovine respiratory disease is the biggest and most costly health challenge facing the cattle industry. The 2 populations used consisted of 1,519 preweaned calves and 3,277 head of feedlot cattle. The incidence rate of BRD in preweaned calves was 11.39%, and among treated cattle, 82.1% were treated once, 13.9% were treated twice, and 4.0% were treated 3 times or more. The incidence of BRD (P = 0.35) and the number of treatments (P = 0.77) had no significant effect on weaning BW. Heritability estimates of the entire preweaned population for BRD resistance and number of treatments were 0.11 ± 0.06 and 0.08 ± 0.05, respectively. The genetic correlation estimates for BRD incidence with weaning BW and birth BW were low (−0.02 ± 0.32 and 0.07 ± 0.27, respectively). The same estimate for the number of BRD treatments with weaning BW and birth BW was 0.25 ± 0.35 and 0.30 ± 0.27, respectively. The observed BRD incidence rate for feedlot cattle was observed at 9.43%. Incidence of BRD significantly (P \u3c 0.01) decreased overall and acclimation ADG by 0.06 ± 0.01 kg/d and 0.28 ± 0.03 kg/d, respectively. Carcass traits were also significantly (P \u3c 0.05) affected by BRD incidence; untreated cattle had a 9.1 ± 1.7-kg heavier HCW. Results were similar in the analysis of treatment frequency. The heritability estimate of BRD incidence and the number of treatments were 0.07 ± 0.04 and 0.02 ± 0.03, respectively. Estimates of genetic correlations of BRD incidence with production traits were −0.63 ± 0.22 for acclimation ADG, −0.04 ± 0.23 for on-test ADG, −0.31 ± 0.21 for overall ADG, −0.39 ± 0.21 for final BW, −0.22 ± 0.22 for HCW, −0.03 ± 0.22 for LM area, 0.24 ± 0.25 for fat, and −0.43 ± 0.20 for marbling score. Similar results for the number of treatments and production traits were −1.00 ± 0.68 for acclimation ADG, −0.04 ± 0.39 for on-test ADG, −0.47 ± 0.41 for overall ADG, −0.66 ± 0.40 for final BW, −0.58 ± 0.45 for HCW, −0.12 ± 0.38 for LM area, 0.42 ± 0.50 for fat, and −0.32 ± 0.37 for marbling score. Because of the high economic cost associated with BRD incidence, even these modest estimates for heritability of BRD resistance should be considered for incorporation into beef cattle breeding programs

    Finishing Beef Cattle on Grass Supplemented with Self-fed By-Products

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    Consumers are showing increasing interest in beef from cattle that are finished or fattened on grass rather than in a conventional feedlot. Also recently, Iowa has had a proliferation of plants that produce ethanol from corn. The by-product of this process is distillers dried grains with solubles (DDGS). The objective of this study was to feed beef cattle to market weight (or as near as possible) by grazing them on cool-season grass supplemented with self-fed byproduct pellets

    Evaluation of Character Displacement Among Plants in Two Tropical Pollination Guilds

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    In cloud forest at Monteverde, Costa Rica, two guilds of bird—pollinated plants exist; on guild pollinated by long—billed hummingbirds, primarily the Green Hermit (Phaethornis guy), and one guild pollinated by short—billed hummingbirds, primarily the Purple—throated Mountain—gem (Lampornis calolaema). Plants were assigned to guilds based on hummingbird visit patterns documented during >4000 plant—hours of field observations, and on identities of pollen grains collected from 600 mist—netted hummingbirds. Other studies indicated that pollination in these plants is often insufficient for maximum seed set. Each guild was examined for character displacement expected within a stable assemblage of plants structured by competition for pollination. (1) By comparing observed flowering phenologies with those obtained through a randomization procedure, we determined whether each species' phenology minimized overlap with the remainder of its guild. (2) We also examined complementarity between phenological displacement and morphological displacement in reproductive structures. Neither guild exhibited pronounced character displacement. (1) In most cases, flowering phenologies were indistinguishable from those generated at random; the few statistically significant departures mostly indicated aggregation, rather than displacement, of flowering seasons. (2) In most cases, morphological similarity was independent of phenological similarity. The only statistically significant result among the studied species was a positive correlation, among long—flowered species only, between rarity and uniqueness of flowering season. We do not conclude that this absence of expected pattern indicates that competition never occurs or that competition is an inconsequential ecological event. Rather, we attribute absence of pattern to the following aspects of biological variability, two of which we have demonstrated in other studies. (1) Within any one year, density—dependent competition for pollination is sporadic, and is not clearly related to flowering season or morphological similarity. (2) The nature of interspecific interactions varies among years, as neither the relative intensities of flowering nor the flowering seasons themselves are consistent from year to year. (3) The nature of interspecific interactions varies with changes in species composition, which occur over short distances. (4) The assemblage of species is probably not stable over long time spans; the species have Gleasonian ecologies that change distribution and abundance faster than natural selection or diffuse competition can screen out improper phenotypes or species, respectively
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