4,918 research outputs found

    Integration of Multimedia Interactive Web Tools with In-Class Active Learning

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    In this paper, we present our experience with an introduction to engineering course in which we used a combination of active and collaborative teaching methods, multimedia web-based material, and web-based interactive tools. The students were engaged in active learning in class with methods such as demonstrations, hands-on work, and group work. After class, the students used the web-based material that we developed, such as multiple choice quizzes, interactive applets, and animations. We have also developed a number of web-based course management tools that were used by the course instructors. We conclude that both the students and instructors had a very positive experience from using this combination of methods

    Studies on proper simulation during static testing of forward speed effects on fan noise

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    Significant differences exist in the noise generated by engines in flight and engines operating on the test stand. It was observed that these differences can be reduced by the use of an inflow control structure (ICS) in the static test configuration. The results of the third phase of a three phase program are described. The work performed in the first two phases which dealt with the development of a model for atmospheric turbulence, studies of fan noise generated by rotor turbulence interaction, and the development of an inflow control structure design system are summarized. The final phase of the program covers procedures for performing static testing with an ICS projecting the resulting static test data to actual flight test data. Included is a procedures report which covers the design system and techniques for static testing and projecting the static data to flight

    Effects of preservation method on canine (Canis lupus familiaris) fecal microbiota.

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    Studies involving gut microbiome analysis play an increasing role in the evaluation of health and disease in humans and animals alike. Fecal sampling methods for DNA preservation in laboratory, clinical, and field settings can greatly influence inferences of microbial composition and diversity, but are often inconsistent and under-investigated between studies. Many laboratories have utilized either temperature control or preservation buffers for optimization of DNA preservation, but few studies have evaluated the effects of combining both methods to preserve fecal microbiota. To determine the optimal method for fecal DNA preservation, we collected fecal samples from one canine donor and stored aliquots in RNAlater, 70% ethanol, 50:50 glycerol:PBS, or without buffer at 25 °C, 4 °C, and -80 °C. Fecal DNA was extracted, quantified, and 16S rRNA gene analysis performed on Days 0, 7, 14, and 56 to evaluate changes in DNA concentration, purity, and bacterial diversity and composition over time. We detected overall effects on bacterial community of storage buffer (F-value = 6.87, DF = 3, P < 0.001), storage temperature (F-value=1.77, DF = 3, P = 0.037), and duration of sample storage (F-value = 3.68, DF = 3, P < 0.001). Changes in bacterial composition were observed in samples stored in -80 °C without buffer, a commonly used method for fecal DNA storage, suggesting that simply freezing samples may be suboptimal for bacterial analysis. Fecal preservation with 70% ethanol and RNAlater closely resembled that of fresh samples, though RNAlater yielded significantly lower DNA concentrations (DF = 8.57, P < 0.001). Although bacterial composition varied with temperature and buffer storage, 70% ethanol was the best method for preserving bacterial DNA in canine feces, yielding the highest DNA concentration and minimal changes in bacterial diversity and composition. The differences observed between samples highlight the need to consider optimized post-collection methods in microbiome research

    Ventrales femoroacetabuläres Impingement nach geheilter Schenkelhalsfraktur

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    Zusammenfassung: Fragestellung.: Darstellung des ventralen femoroacetabulären Impingements (VFAI) als Ursache persistierender schmerzhafter Bewegungseinschränkungen und fortschreitender Gelenkschädigung nach geheilter Schenkelhalsfraktur sowie der Ergebnisse nach operativer Therapie des VFAI. Methodik.: Bei 11Patienten wurde ein VFAI mit bewegungs- und belastungsabhängigen Leistenschmerzen nach in Retrotorsion geheilter Schenkelhalsfraktur vermutet und nativröntgenologisch sowie mit radialer Arthro-MRT-Untersuchung bestätigt. Mit chirurgischer (Sub-)Luxation des Hüftgelenks wurde das Impingement offen überprüft und durch Wiederherstellung der Kontur des anterioren Übergangs zwischen Femurkopf und Schenkelhals beseitigt. Ergebnisse.: Bei sämtlichen Patienten zeigte sich eine Abflachung der Kontur des ventralen Kopf-Hals-Übergangs und ein dadurch hervorgerufenes Cam-Impingement mit konsekutiver Schädigung des pfannenrandnahen acetabulären Knorpels. Bei der Nachuntersuchung 5Jahre postoperativ fand sich eine deutliche Besserung der Symptomatik ohne Zunahme der Gelenkschädigung. Schlussfolgerung.: Bei chronischen Beschwerden nach geheilter Schenkelhalsfraktur ohne Kopfnekrose ist an die Möglichkeit eines VFAI durch Retrotorsion des Kopfes gegenüber dem Hals zu denken. Die durch VFAI hervorgerufene Symptomatik lässt sich durch chirurgische Optimierung des Kopf-Hals-Offset längerfristig verbessern. Ein bereits entstandener Gelenkschaden lässt sich allerdings kaum angehen. Eine Schenkelhalsfraktur sollte anatomisch reponiert werden, um der Arthroseentwicklung vorzubeuge

    Analytic models of ducted turbomachinery tone noise sources. Volume 1: Analysis

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    The analytic models developed for computing the periodic sound pressure of subsonic fans and compressors in an infinite, hardwall annular duct with uniform flow are described. The basic sound-generating mechanism is the scattering into sound waves of velocity disturbances appearing to the rotor or stator blades as a series of harmonic gusts. The models include component interactions and rotor alone

    Analytic models of ducted turbomachinery tone noise sources. Volume 3: Program test case results

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    Computer programs for analyzing the acoustic properties of turbomachinery with ducted flow were developed. The models include component interactions and rotor alone. Test case results determined from the computer programs are presented

    Analytic models of ducted turbomachinery tone noise sources. Volume 2: Subprogram documentation

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    Analytical models were developed for computing the periodic sound pressures of subsonic fans in an infinite hardwall annular duct with uniform flow. The computer programs are described which are used for numerical computations of sound pressure mode amplitudes. The data are applied to the acoustic properties of turbomachinery
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