196,186 research outputs found
New insights on the use of magnetic particles for lake restoration: toxicity assessment and evaluation of the viability of recovered phosphorus as a fertilizer
No full textFirstly, our results from single-species acute and chronic toxicity tests using phytoplankton (Chlorella sp. and Raphidocelis subcapitata), zooplankton (Daphnia magna and Brachionus calyciflorus) and benthic organisms (Chironomus sp.) have shown that using MPs for reducing P concentration in lake water and lake sediment is a risk-less (no toxic effect) and efficient (high P adsorption capacity) tool for lake restoration. This statement is based on the higher values measured in this PhD for the concentration of MPs that caused an effect (EC50) or the death (LC50) in 50% of organims compared to the required MPs concentration. At this point, it is worth to note x
that MPs concentration to be added in a real lake restoriation project, can be estimated considering the 53 mg MPs: mg P mass ratio as the adsorption efficiency ratio (de Vicente et al., 2010) and the typical concentration of lake water P concentration in eutrophicated ecosystems.
To get a comparison of the toxicity of MPs with other novel P adsorbents (magnetite, Phoslock® and CFH-12®), several toxicity tests were also run. In particular, the acute effects on both the green algae R. subcapitata (growth rate inhibition test) and on D. magna (immobilization) were assessed. To discriminate between chemical and physical effects of adsorbents on D. magna, the immobilization test was run both in direct and in indirect contact (by using a double beaker) with the different P adsorbents. Results evidenced that when organisms were exposed to a direct contact in the D. magna immobilization test, no statistically significant differences were found in the EC50 values among the four studied adsorbents. Additionally, the huge difference between direct and indirect contact experiments suggests that toxicity is mainly physically mediated. Finally, an uptake-depuration test was carried out for assessing the response of D. magna after being in direct contact with adsorbents for 24 h. Fe and La body burdens contents, monitored during 24 h-uptake and 24 h-depuration tests, showed that neither accumulation nor longer term effects of P adsorbents is expected. As a result, the risk for toxicity may, on a case-to-case basis, be acceptable.
In order to get a more realistic effect of MPs addition on the whole zooplankton community, microcosm experiments containing lake water and lake sediment from an hypertrophic ecosystem (Honda lake, Almería) were carried out. Results confirmed that MPs adition did not significantly affect zooplankton total abundance, species richness and species diversity. The absence of any effect of MPs on zooplankton was explained because MPs did not significantly alter any of its physico-chemical (e.g. temperature, pH, O2) or biological (e.g. food quantity and quality) drivers.
Secondly, we have proved the suitability of using MPs for removing P in treated wastewaters. Therefore, high values of both equilibrium adsorption capacity (q) and P removal efficiency of MPs have been measured when adding MPs to treated wastewaters with lastly discharge in the Fuente de Piedra Ramsar site. Accordingly, MPs addition can be proposed as a reliable countermeasure to reduce the impact of wastewater effluents in this Ramsar site. Even more, and considering both advantages (P removal efficiency, %) and disadvantages (economic price, € L-1) of using MPs, we xi
have identified an optimum ratio ≥ 0.16 g MPs mg-1 P when adding MPs to treated wastewaters.
In the last Chapter, and based on both nutrient concentrations used in previous studies and the cost-effectiveness of the method in a long-term, we select 0.1 M NH4OH (neutralized with H3PO4) as the best option for desorbing P from P loaded MPs. Actually, P concentration in the selected conditions was so high that it was necessary to dilute the supernatants, making profitable to use recovered P as a fertilizer. Fertirrigation experiments showed marked differences in the germination patterns among the three plants species. The first species in germinating was O. bassilicum but it later experienced a slower tendency and at the end of the experiment the highest percentage of germination was 80%, which corresponded to the control. The germination of the other two species, C. sativus and C. melo, started later (from day 4) and it generally reached values up to 100% at the end of the experiment. Even more, germination in the different treatments experienced notable differences among plants species. While in O. bassilicum, the germination in the Control was also higher than in the other treatments for any time of the experiment; for C. sativus and C. melo, the percentage of germination in all treatments was higher than in Control, evidencing the key role of adding nutrients for the germination of these species. In general, height and growth rate for the three plants species was significantly lower in control than in treatments. Additionally, it is worth to note that no significant differences were found when using commercial fertilizer or recovered P from the P loaded MPs. Similarly, shoot and root biomass as well as P concentration in shoot was significantly lower in control than in treatments while no significant differences when using a commercial fertilizer and recovered P were found. These results suggest that P desorbed from P loaded MPs can be used as a liquid fertilizer. As a result, our results are promising in order to counteract the widespread and coupled problems of the exhaustion of the P reserves and the eutrophication of aquatic ecosystems.En primer lugar, los resultados de los tests de toxicidad aguda y crónica con una única especie de fitoplancton (Chlorella sp. y Raphidocelis subcapitata), zooplancton (Daphnia magna y Brachionus calyciflorus) y organismos bénticos (Chironomus sp.) han demostrado que la utilización de MPs para la reducción de la concentración de P presenta una toxicidad reducida sobre los organismos acuáticos. Esta afirmación se basa xiii
en que los valores de la concentración de MPs que causa un efecto (EC50) o la muerte (LC50) en el 50% de los organismos es superior a la concentración de MPs estimada para proyectos de restauración. En este punto, es importante tener presente que la concentración de MPs a adicionar se puede estimar considerando la relación 53 mg MP: mg P (de Vicente et al., 2010) así como la concentración típica en ecosistemas eutrofizados.
Para obtener una comparación de la toxicidad de las MPs con otros novedosos adsorbentes de P (magnetita, Phoslock® y CFH-12®), también se realizaron varias pruebas de toxicidad. En particular, se evaluaron los efectos agudos tanto sobre R. subcapitata (prueba de inhibición de la tasa de crecimiento) como en D. magna (inmovilización). Para discriminar entre los efectos químicos y físicos de los adsorbentes en D. magna, la prueba de inmovilización se realizó en contacto directo e indirecto (utilizando un doble vaso de precipitados) con los diferentes adsorbentes de P. Los resultados han mostrado claramente el predominio de un efecto físico de los adsorbentes sobre los organismos. Finalmente, se llevó a cabo una prueba de asimilación-depuración para evaluar la respuesta de D. magna después de estar en contacto directo con los adsorbentes durante 24 h. La concentración de Fe y de La en los organismos reflejó la ausencia de acumulación así como de efectos a largo plazo de los adsorbentes de P. Por tanto, podemos concluir que el riesgo de toxicidad puede, según el caso, ser aceptable.
Para obtener un efecto más realista de la adición de MPs en toda la comunidad de zooplancton, se llevaron a cabo experimentos de microcosmos que contenían agua y sedimento superficial de un lago hipereutrófico (laguna Honda, Almería). Los resultados confirmaron que la adición de MPs no causa efectos significativos ni en la abundancia total, ni en la riqueza de especies ni en la diversidad de especies del zooplancton. La ausencia de efectos de la adición de MPs sobre la comunidad zooplanctónica puede explicarse por la no alteración ni de los condicionantes físico-químicos (por ejemplo, temperatura, pH, O2) ni biológicos (por ejemplo, cantidad y calidad de alimento).
En relación al segundo objetivo de esta Tesis, las MPs han mostrado una elevada eficiencia para retirar P en aguas residuales tratadas. Esta afirmación se basa tanto en la elevada capacidad de adsorción de P en equilibrio (q) así como en la eficiencia de retirada de P por las MPs. Teniendo en cuenta tanto las ventajas (eficiencia de retirada xiv
de P) como las desventajas (coste económico) de usar MPs, hemos identificado que la dosis óptima a utilizar es ≥ 0.16 g MPs mg-1 P.
En el último Capítulo, y tras la comparación de la concentración de P medida en los extractos al utilizar tres diferentes soluciones básicas (NaOH; KOH y NH4OH), podemos concluir que la mejor opción para desorber P es la utilización de 0.1 M NH4OH (neutralizado con H3PO4). De hecho, la concentración de P en las condiciones seleccionadas fue tan alta que fue necesario diluir los sobrenadantes, lo que optimiza el uso del P recuperado como fertilizante.
Finalmente, en los experimentos de fertirrigación con O. bassilicum, C. sativus y C. melo, se observó que la altura y la tasa de crecimiento para las tres especies de plantas fue significativamente menor en el control (sin adición de nutrientes) que en los tratamientos. Más aún, es importante destacar la ausencia de diferencias significativas entre los tratamientos con fertilizante comercial y con P recuperado. De manera similar, la biomasa de las partes aéreas y de las raíces, así como la concentración de P en las partes aéreas fue significativamente más baja en los controles que en los tratamientos, mientras que no se encontraron diferencias significativas entre los tratamientos (fertilizante comercial vs P recuperado). Estos resultados sugieren que el P desorbido desde las MPs puede usarse como fertilizante líquido. Por tanto, las MPs podrían ser porpuestas para contrarrestar la alteración antrópica del ciclo biogeoquímico del P.Tesis Univ. Granada.Proyectos de Excelencia de la Junta de Andalucía P10-RNM-6630.Proyectos nacionales del Ministerio de Economía y Competitividad MINECO CTM 2013-46951-R.Fondo Europeo de Desarrollo Regional (FEDER)
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Intern experience at CH���M Hill, Inc.: an internship report
No full textIncludes author's vita"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirement for the degree of Doctor of Engineering."Includes bibliographical referencesA review of the author's internship experience with CH���M HILL, Inc.
during the period September 1975 through May 1976 is presented. During this nine month
internship the author worked as an Engineer II in the Industrial Processes discipline of this
large consulting engineering firm... The author's prime responsibility was as one of three
lead design engineers on the design of a large wastewater treatment facility for a pulp mill
in Hoquiam, Washington owned by ITT Rayonier Inc. The work generally consisted of the design
of individual treatment units and associated piping and pumping. The purpose of the project
was to provide wastewater treatment capabilities that would satisfy the effluent limitations
(standards) imposed upon the mill by the State of Washington Department of Ecology and the
U.S. Environmental Protection Agency. The author's assignment also entailed necessary
interaction with the project manager and other CH���M HILL design engineers and support staff
members, the client's representatives, and representatives of two other consulting engineering
firms working on the project. Thus, the internship position at CH���M HILL provided considerable
experience coordinating the author's work with the work of other engineers, guiding the design
and administrative efforts of a support staff, and interacting regularly with the client and
other consulting firms. This broad exposure to a variety of engineering and organizational
problems provided a valuable educational experience
Transition to turbulence in a qblique shock-wave/boundary-layer interaction at M=15
No full textDirect numerical simulations are carried out for different forcing techniques to trigger transition during the interaction between an oblique shock-wave and a laminar boundary-layer at M = 1.5. Three forcing methods are used: a) forcing of oblique unstable modes, whose shape and behaviour are determined by the local linear stability theory, b) broadband free-stream acoustic disturbances, and c) a cold plasma flow control device. While the oblique-mode breakdown is dominant for low-amplitude forcing, long streaky structures drive the transition process in a high-amplitude disturbance environment. LES are also performed on the experimental setup by the Institute of Theoretical and Applied Mechanics (ITAM) from Novosibirsk State University with cold plasma actuation. As well as the disturbance type, the effect of Reynolds number and forcing amplitude will be investigated
Letter from Cedrick M. Shimo to the Office of Redress Administration, June 4, 1991
No full textA letter from Cedrick M. Shimo to the Office of Redress Administration arguing that John Y. Udaka is entitled to a redress payment.These materials are from box 73 and 74 of the Frank Chin Papers. The Frank Chin Papers contain personal and professional correspondence between Frank Chin and Michi Weglyn relating to particular projects on which either author was working as well as files related to the Day of Remembrance Tribute to Michi Weglyn
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
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