83 research outputs found
The Lived Experience of Graduate Nursing Students in Distance Education
This study explored the lived experience of graduate nursing students enrolled in an interactive television course offered through distance education. Areas of focus were the technology of distance education, instructional strategies, the learning community, and communication. The qualitative research methods of interviewing, observation, and artifact/documentation review were employed. Students reported returning to school for both personal and professional reasons; self-satisfaction was most frequently mentioned. The need to work in a changing health care system was the major professional reason given. Due to multiple role responsibilities which made the participants time- and place-bound, distance education was reported to be the only way the students were able to participate in affordable, quality higher education. Computers appeared to play a major role in the students\u27 learning experience. Commitment by the College of Nursing to deliver the program in an orderly manner was perceived as weak and created anxiety in the students. Student supports such as enrollment services, advisement, library services, and communication channels were present during this distance education event and appeared to be adequate. A variety of teaching/learning strategies used by a dynamic instructor were perceived by the students as being important for their learning
âAt hedde et billedeâ : en undersøgelse af betydningsdannelsen i logotyper
Vores interesse for logotyper tager sit udgangspunkt to steder: I vores fĂŚlles interesse for henholdsvis visuelle kommunikationsformer og de mĂĽder, hvorpĂĽ virksomheder kommunikerer med deres omverden. Vores interesse for visuelle kommunikationsformer er overvejende praktisk funderet, da Christian driver Ăje for Ăje illustration ved siden af studierne, og Henrik er freelancefotograf. Specialet her er dog udtryk for en lyst til undersøge teorien bag visuel kommunikation. Interessen for virksomheders kommunikation er stadig overvejende teoretisk funderet. Vi har med vores fĂŚlles uddannelsesbaggrund i Nordisk og Virksomhedskommunikation haft rig lejlighed til, pĂĽ et teoretisk niveau, at beskĂŚftige os med generel kommunikationsteori og mere specifik virksomhedskommunikationsteori. Disse to interesseomrĂĽder smelter sammen i vores intention om at belyse logotyper, der er en kommunikationsform, vi alle konfronteres med dagligt - for langt de flestes vedkommende dog uden at det afføder nogen nĂŚvnevĂŚrdig undren. Vi undrer os imidlertid over at logotypen, sĂĽ vidt vi har kunnet konstatere, hidtil er blevet overset af sprogteoretikere og aldrig er blevet underkastet en stringent metodisk videnskabelig undersøgelse som en selvstĂŚndig kommunikationsform. Det ønsker vi med dette speciale at tage de første skridt til at ĂŚndre. Vi mener, at det er relevant at tage hul pĂĽ undersøgelsen af logotyper som selvstĂŚndig kommunikationsform, fordi tendensen i de vestlige samfund peger i retning af, at det nuvĂŚrende samfunds hyperkompleksitet (Qvortrup 2000) langt fra har nĂĽet sin kulmination. I det hyperkomplekse samfund vil efterspørgslen efter simple kommunikationsmekanismer, der kan sammenkĂŚde eller overføre store mĂŚngder af information og dermed reducere kompleksitet, stige. Som undersøgelsen i specialet vil vise, er logotyper netop en kommunikationsform af den simpelhed, der vil blive efterspurgt i det hyperkomplekse samfund. Paradoksalt nok spiller logotyper i kraft af deres simplicitet en forbløffende stor rolle for moderne virksomheder. Det er ikke uden ĂĽrsag at noget af det første, grundlĂŚggeren af en moderne virksomhed sĂŚtter sine krĂŚfter ind pĂĽ, er at finde det rigtige navn til virksomheden og i forlĂŚngelse heraf at fĂĽ skabt den rigtige logotype. Først i det øjeblik disse to identifikatorer er pĂĽ plads, begynder den ny virksomhed at føles manifest. Logotypen spiller rollen som bĂŚrer af identitet, og som specialet vil vise, afføder det hyperkomplekse samfund kravet om en fortĂŚttet identitet
Foliar lead uptake by lettuce exposed to atmospheric fallouts
Metal uptake by plants occurs by soilâroot transfer but also by direct transfer of contaminants from the atmosphere to the shoots. This second pathway may be particularly important in kitchen gardens near industrial plants. The mechanisms of foliar uptake of lead by lettuce (Lactuca sativa) exposed to the atmospheric fallouts of a lead-recycling plant were studied. After 43 days of exposure, the thoroughly washed leaves contained 335 Âą 50 mg Pb kgâ1 (dry weight). Micro-X-ray fluorescence mappings evidenced Pb-rich spots of a few hundreds of micrometers in diameter located in necrotic zones. These spots were more abundant at the base of the central nervure. Environmental scanning electron microscopy coupled with energy dispersive X-ray microanalysis showed that smaller particles (a few micrometers in diameter) were also present in other regions of the leaves, often located beneath the leaf surface. In addition, submicrometric particles were observed inside stomatal openings. Raman microspectrometry analyses of the leaves identified smelter-originated Pb minerals but also secondary phases likely resulting from the weathering of original particles. On the basis of these observations, several pathways for foliar lead uptake are discussed. A better understanding of these mechanisms may be of interest for risk assessment of population exposure to atmospheric metal contamination
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Bioavailability in soils
The consumption of locally-produced vegetables by humans may be an important exposure pathway for soil contaminants in many urban settings and for agricultural land use. Hence, prediction of metal and metalloid uptake by vegetables from contaminated soils is an important part of the Human Health Risk Assessment procedure. The behaviour of metals (cadmium, chromium, cobalt, copper, mercury, molybdenum, nickel, lead and zinc) and metalloids (arsenic, boron and selenium) in contaminated soils depends to a large extent on the intrinsic charge, valence and speciation of the contaminant ion, and soil properties such as pH, redox status and contents of clay and/or organic matter. However, chemistry and behaviour of the contaminant in soil alone cannot predict soil-to-plant transfer. Root uptake, root selectivity, ion interactions, rhizosphere processes, leaf uptake from the atmosphere, and plant partitioning are important processes that ultimately govern the accumulation ofmetals and metalloids in edible vegetable tissues. Mechanistic models to accurately describe all these processes have not yet been developed, let alone validated under field conditions. Hence, to estimate risks by vegetable consumption, empirical models have been used to correlate concentrations of metals and metalloids in contaminated soils, soil physico-chemical characteristics, and concentrations of elements in vegetable tissues. These models should only be used within the bounds of their calibration, and often need to be re-calibrated or validated using local soil and environmental conditions on a regional or site-specific basis.Mike J. McLaughlin, Erik Smolders, Fien Degryse, and Rene Rietr
Mercury isotopes in a forested ecosystem: Implications for airâsurface exchange dynamics and the global mercury cycle
Forests mediate the biogeochemical cycling of mercury (Hg) between the atmosphere and terrestrial ecosystems; however, there remain many gaps in our understanding of these processes. Our objectives in this study were to characterize Hg isotopic composition within forests, and use natural abundance stable Hg isotopes to track sources and reveal mechanisms underlying the cycling of Hg. We quantified the stable Hg isotopic composition of foliage, forest floor, mineral soil, precipitation, and total gaseous mercury (THg (g) ) in the atmosphere and in evasion from soil, in 10âyearâold aspen forests at the Rhinelander FACE experiment in northeastern Wisconsin, USA. The effect of increased atmospheric CO 2 and O 3 concentrations on Hg isotopic composition was small relative to differences among forest ecosystem components. Precipitation samples had δ 202 Hg values of â0.74 to 0.06â° and â 199 Hg values of 0.16 to 0.82â°. Atmospheric THg (g) had δ 202 Hg values of 0.48 to 0.93â° and â 199 Hg values of â0.21 to â0.15â°. Uptake of THg (g) by foliage resulted in a large (â2.89â°) shift in δ 202 Hg values; foliage displayed δ 202 Hg values of â2.53 to â1.89â° and â 199 Hg values of â0.37 to â0.23â°. Forest floor samples had δ 202 Hg values of â1.88 to â1.22â° and â 199 Hg values of â0.22 to â0.14â°. Mercury isotopes distinguished geogenic sources of Hg and atmospheric derived sources of Hg in soil, and showed that precipitation Hg only accounted for ~16% of atmospheric Hg inputs. The isotopic composition of Hg evasion from the forest floor was similar to atmospheric THg (g) ; however, there were systematic differences in δ 202 Hg values and MIF of even isotopes (â 200 Hg and â 204 Hg). Mercury evasion from the forest floor may have arisen from airâsurface exchange of atmospheric THg (g) , but was not the emission of legacy Hg from soils, nor reâemission of wetâdeposition. This implies that there was net atmospheric THg (g) deposition to the forest soils. Furthermore, MDF of Hg isotopes during foliar uptake and airâsurface exchange of atmospheric THg (g) resulted in the release of Hg with very positive δ 202 Hg values to the atmosphere, which is key information for modeling the isotopic balance of the global mercury cycle, and may indicate a shorter residence time than previously recognized for the atmospheric mercury pool. Key points Atmospheric Hg was fractionated during uptake by foliage (â2.89 permil δ202Hg) Hg evading from soil was from atmospheric Hg interaction with soil environment Airâsurface exchange of Hg releases Hg with positive δ202Hg to global reservoirPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/1/2011GB004202RRts04.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/2/2011GB004202RRts05.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/3/2011GB004202RRts01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/4/gbc20021.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/5/2011GB004202RRts06.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/6/2011GB004202RRts02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/7/2011GB004202RRts07.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97463/8/2011GB004202RRts03.pd
Enhancing methane production from lignocellulosic biomass by combined steamâexplosion pretreatment and bioaugmentation with cellulolytic bacterium Caldicellulosiruptor bescii
Background: Biogas production from lignocellulosic biomass is generally considered to be challenging due to the recalcitrant nature of this biomass. In this study, the recalcitrance of birch was reduced by applying steam-explosion (SE) pretreatment (210 °C and 10 min). Moreover, bioaugmentation with the cellulolytic bacterium Caldicellulosiruptor bescii was applied to possibly enhance the methane production from steam-exploded birch in an anaerobic digestion (AD) process under thermophilic conditions (62 °C). Results: Overall, the combined SE and bioaugmentation enhanced the methane yield up to 140% compared to untreated birch, while SE alone contributed to the major share of methane enhancement by 118%. The best methane improvement of 140% on day 50 was observed in bottles fed with pretreated birch and bioaugmentation with lower dosages of C. bescii (2 and 5% of inoculum volume). The maximum methane production rate also increased from 4-mL CH4/ g VS (volatile solids)/day for untreated birch to 9-14-mL CH4/ g VS/day for steam-exploded birch with applied bioaugmentation. Bioaugmentation was particularly effective for increasing the initial methane production rate of the pretreated birch yielding 21-44% more methane than the pretreated birch without applied bioaugmentation. The extent of solubilization of the organic matter was increased by more than twofold when combined SE pretreatment and bioaugmentation was used in comparison with the methane production from untreated birch. The beneficial effects of SE and bioaugmentation on methane yield indicated that biomass recalcitrance and hydrolysis step are the limiting factors for efficient AD of lignocellulosic biomass. Microbial community analysis by 16S rRNA amplicon sequencing showed that the microbial community composition was altered by the pretreatment and bioaugmentation processes. Notably, the enhanced methane production by pretreatment and bioaugmentation was well correlated with the increase in abundance of key bacterial and archaeal communities, particularly the hydrolytic bacterium Caldicoprobacter, several members of syntrophic acetate oxidizing bacteria and the hydrogenotrophic Methanothermobacter. Conclusion: Our findings demonstrate the potential of combined SE and bioaugmentation for enhancing methane production from lignocellulosic biomass
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