176,813 research outputs found
Retinography versus fluorescein angiography in the evaluation of diabetic retinopathy.
No full text[no abstract available
Retinography versus fluorescein angiography in macular hyperplasia of retinal pigment epithelium: a ten years follow up report.
No full text[no abstract available
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
Intern experience at the Texas Transportation Institute: an internship report
No full text"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirements for the degree of Doctor of Engineering."Includes vita (leaf 91)Includes bibliographical references (leaf 57)This report discusses the author's engineering experience at the Texas
Transportation Institute (TTI), Texas A&M University from March 1974 through July 1977. A
report of this experience plus twelve additional hours of academic course work were
substituted for an internship according to requirements established by the College of
Engineering. Although the author could not retroactively establish objectives of the type
associated with a typical internship, the work experience gained could be related to the two
general objectives of an intership: 1. To demonstrate an identifiable contribution to the
organization in which the intern served, and 2. To enable the intern to become aware of the
non-technical aspects of working as an engineer in a non-academic environment. While a member
of the Texas Transportation Institute staff, the author worked on a number of projects in the
areas of highway traffic engineering research and the preparation of continuing education
courses for transportation engineering officials. These assignments were contained within the
Urban Transportation Systems Division of TTI. This report delineates the author's contribution
to four particular projects and discusses the technical as well as non-technical experience
gained from each. Having been exposed to more engineering situations than many of the other
Doctor of Engineering students, the author has already formulated some rather specific
milestones for the future. The Doctor of Engineering program is discussed in conjunction with
its potential for helping the author attain these career goals and objectives. Also, some
thoughts are presented regarding the Doctor of Engineering as a viable alternative to the
Ph.D. in preparing for a career in engineering higher education
The long-wavelength view of GG Tau A: rocks in the ring world
No full textWe present the first detection of GG Tau A at centimetre wavelengths, made with the Arcminute Microkelvin Imager Large Array at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at >6 σrms with an integrated flux density of S16GHz = 249 ± 45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long-wavelength tail of the dust emission from this unusual protoplanetary system. We use an MCMC-based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of Md ~ 0.1 Msun, constrain the dimensions of the emitting region and find that the opacity index at λ > 7 mm is less than unity, implying a contribution to the dust population from grains exceeding ~4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association in combination with the low derived disc mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models
Polyaniline Intercalation In α-sn(hpo4)2.h2o
No full textIn this work we report the preparation of a inorganic-organic nanocomposite, obtained by the in situ oxidative polymerization of aniline inside the layers of α-Sn(HPO4)2.H2O (α-SnP). Two approaches were used to obtain the α-SnP/polyaniline nanocomposite. Firstly, hydrogen atoms of α-SnP were exchanged with Fe3+ cation to promote aniline polymerization. Secondly, aniline was intercalated in α-SnP and polymerization was performed by (NH4)2S2O8 solution. Both resulting material leads to formation of polyaniline in its conducting form, the emeraldine salt. The characterization results suggest the formation of linear polymer chains between the α-SnP layers.1021-312771278Geniès, E.M., Boyle, A., Lapkowski, M., Tsintavis, C., (1990) Synth. Met., 36, p. 139Enzel, P., Bein, T., (1989) J. Phys. Chem., 93, p. 6270Maia, D.J., Zarbin, A.J.G., Alves, O.L., De Paoli, M.-A., (1995) Adv. Mater., 7, p. 792Zarbin, A.J.G., De Paoli, M.-A., Alves, O.L., (1997) Synth. Met., 84, p. 107Maia, D.J., Alves, O.L., De Paoli, M.-A., (1997) Synth. Met., 90, p. 37Whittinghan, M.S., Jacobson, A.J., (1982) Intercalation Chemistry, p. 147. , Academic PressConstantino, U., Gasperoni, A., (1970) J. Chromatogr., 51, p. 289Furukawa, Y., Hara, T., Hyodo, Y., Harada, I., (1986) Synth. Met., 16, p. 189Geniès, E.M., Lapkowski, M., Penneau, J.F., (1988) J. Electroanal. Chem., 249, p. 9
Choroidal calcification in Bartter syndrome
No full textPURPOSE: Bartter syndrome is characterized by hyperplasia of the renal juxtaglomerular apparatus, hyperaldosteronism, and hypokalemic alkalosis. We report a case of Bartter syndrome associated with normal serum calcium levels and posterior choroidal calcification. METHODS: Case report. A 59-year-old man with bilateral cataract and Bartter syndrome underwent a complete ophthalmic examination, including standardized echography before and after cataract surgery. RESULTS: Before cataract surgery, echography identified small, hyperreflective, multifocal, bilateral choroidal lesions with posterior shadowing. After surgery, these lesions appeared as yellow-white, barely elevated plaques with smooth edges and were diagnosed as choroidal calcification. CONCLUSIONS: Choroidal calcification may occur in patients with Bartter syndrome. This condition should be added to the differential diagnosis of posterior segment calcification
New Polyaniline/porous Glass Composite
No full textIn this work we report the preparation of a glass-polymer composite, obtained by the in situ oxidative polymerization of aniline, in the pores of Porous Vycor Glass (PVG). A piece of PVG was added to acid aniline solution. PVG adsorbs aniline via an ion-exchange process (H+ from PVG porous surface/C6H5NH3 +). The impregnated PVG was added to a (NH4)2S2O8 acid solution. The glass gradually went to dark green with the formation of polyaniline in its conducting form, the emeraldine salt. The counter-anions are the SiO- groups on the pores surface of the glass, as confirmed by 29Si-CP-MAS-NMR. Addition of the composite to an NH4OH solution leads do a change from dark green to dark blue (emeraldine base), and this process is reversible.8401/03/15107108Chinn, D., Dubow, J., Liess, M., Josowicz, M., Janata, J., (1995) Chem. Mater., 7, p. 1504Kanatzidis, M.G., (1990) Chem Eng. News, DEC.3, p. 36Wuang, W.S., Humphrey, B.D., MacDiarmid, A.G., (1986) J. Chem. Soc., Faraday Trans. 1, 82, p. 2385Geniès, E.M., Boyle, A., Lapkowski, M., Tsintavis, C., (1990) Synth. Met., 36, p. 139Enzel, P., Bein, T., (1989) J. Phys. Chem., 93, p. 6270(1979) Mater. Eng., 90, p. 92Maia, D.J., Zarbin, A.J.G., Alves, O.L., De Paoli, M.A., (1995) Adv. Mater., 7, p. 792Furukawa, Y., Hara, T., Hyodo, Y., Harada, I., (1986) Synth. Met., 16, p. 18
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