3,782 research outputs found
Potential Structural Materials and Design Concepts for Light Airplanes
Potential structural materials and design considerations for helicopters and light general aircraf
Letter from J. C. Waterman
Letter in response of a position in the military department at Utah Agricultural College
An ellipsometric study of protein adsorption at the saliva-air interface
At the liquid-air interface of human saliva a protein layer is adsorbed. From ellipsometric measurements it was found that the thickness of the surface layer ranged from 400 to 3600 Å and the amount of protein material adsorbed was 9–340 mg/m2. Based on the concentration of protein in the layer the samples could be classified into two groups: a low concentration (ca. 0.15 g/ml) and a high concentration (0.7–1.1 g/ml). In the low concentration group the surface layers appeared to be thin (500–600 Å) while those in the high concentration group appeared to be much thicker (1000–3500 Å). A correlation between the bulk pH and the thickness of the surface layer could be established
Potential structural materials and design concepts for light airplanes Final report
Potential structural materials and design concepts evaluated for light aircraft application
Explanation of the Tao effect
In a series of experiments Tao and coworkers\cite{tao1,tao2,tao3} found that
superconducting microparticles in the presence of a strong electrostatic field
aggregate into balls of macroscopic dimensions. No explanation of this
phenomenon exists within the conventional theory of superconductivity. We show
that this effect can be understood within an alternative electrodynamic
description of superconductors recently proposed that follows from an
unconventional theory of superconductivity. Experiments to test the theory are
discussed.Comment: Submitted to Science January 2nd, declined January 6th; to Nature
January 7th, declined January 13th; to PRL January 14th, declined February
25t
Rheological properties of human saliva
From measurements with a Couette-type viscometer provided with a guard ring it was shown that at the saliva-air interface a protein layer is adsorbed. Measurements of the surface shear modulus of this layer on saliva of 7 healthy subjects were performed at a frequency of about 70 Hz and a temperature of 25 °C. For a surface age of about 1.5 h the surface shear modulus and the surface viscosity were in the order of 1 Nm−1 and 10−3 Nm−1 s, respectively. From ellipsometric measurements it was found that the thickness of the protein layer was approx. 100nm and, using this value, it could be concluded that the shear modulus and the dynamic viscosity were in the order of 107 Pa and 104 Pa s, respectively. The layer appeared to be fragile. Even shear deformation amplitudes of 4 × 10−5 are too high to assure linearity. The complex viscosity (η = η′ − iη′′) of the bulk liquid of human submandibular saliva below the absorbed layer was measured in the frequency range 70 Hz–200 kHz with 3 torsional resonators, each for a different frequency, and a Ni-tube resonator. It was concluded, that the real part of the complex viscosity (η′) decreases from 1.1 mPa s at 70 Hz to a value of 0.95 mPa s at high frequencies. Except at the lowest frequency (70 Hz), the value of η′′ was too small to be detected
An Analysis of Employment Perceptions Of Secondary Level School Administrators Holding Joint Positions as Assistant Principal and Athletic Director
The purpose of this descriptive research study was to investigate the employment perceptions of secondary level school administrators holding joint positions as assistant principal and athletic director. To accomplish this purpose, current research and literature concerned with the job responsibilities and qualifications of both positions were reviewed. In addition to the review of literature, a questionnaire was developed for the purpose of identifying and analyzing the (1) general background of each respondent, (2) the general training and experience of each respondent, (3) personal qualifications of each respondent, ( 4) the roles and responsibilities of each respondent, and (5) the employment perceptions of each respondent. The investigator sought to (a) analyze data collected from a survey of secondary level administrators that were employed as both an assistant principal and athletic director in the State of Washington, and (b) report the results of the analysis. Survey responses were tabulated by frequency and percentage, and provided a basis for descriptive analysis of data obtained
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