An experimental evaluation of metallic diaphragms for positive fuel expulsion in the atmosphere explorer hydrazine propulsion subsystem

Four Arde conospheroid metallic diaphragms were tested to evaluate their capability for use in the orbit adjust propulsion subsystem (OAPS) of the Explorer spacecraft. The diaphragms will be used for positive propellant expulsion and spacecraft center of mass control. A leak-free cycle life capability of nine reversals was demonstrated. The diaphragms rolled smoothly from ring to ring in a predictable manner on the first reversal. Varying amounts of diaphragm cocking and ring skipping were observed on subsequent reversals. The diaphragm pressure differential did not exceed 7 N/sq cm during any reversal. Cycle life capability, reversal mode, and pressure differential were not affected by sudden reversals, environmental tests, or 18,000 partial reversals. An expulsion efficiency of approximately 97 percent was demonstrated. The results of these tests show that metallic diaphragms can be used as an effective means of positive fuel expulsion; however, to achieve spacecraft center of mass control, the diaphragm must not be reversed prior to flight

Mexican-American Entrepreneurship

Although business ownership has implications for income inequality, wealth accumulation and job creation, surprisingly little research explores why Mexican-Americans are less likely to start businesses and why the businesses that they start are less successful on average than non-Latino whites. We conduct a comprehensive analysis of Mexican-American entrepreneurship using microdata from the 2000 U.S. Census, the matched and unmatched March and Outgoing Rotation Group Files of the Current Population Survey from 1994 to 2004, and the Legalized Population Survey (LPS). We find that low levels of education and wealth explain the entire gap between Mexican immigrants and non-Latino whites in business formation rates. Nearly the entire gap in business income for Mexican immigrants is explained by low levels of education and limited English language ability. Using the natural experiment created by the Immigration Reform and Control Act (IRCA), we find that legal status represents an additional barrier for Mexican immigrants. A conservative estimate suggests that the lack of legal status reduces business ownership rates by roughly seven-tenths of a percentage point for both men and women. Human and financial capital deficiencies are found to limit business ownership and business success among second and third-generation Mexican-Americans, but to a lesser extent. These findings have implications for the debates over the selection of immigrants and the assimilation of Mexican-Americans in the U.S. economy.Mexican-Americans, entrepreneurship, inequality

Mexican-American Entrepreneurship

Although business ownership has implications for income inequality, wealth accumulation and job creation, surprisingly little research explores why Mexican-Americans are less likely to start businesses and why the businesses that they start are less successful on average than non-Latino whites. We conduct a comprehensive analysis of Mexican-American entrepreneurship using microdata from the 2000 U.S. Census, the matched and unmatched March and Outgoing Rotation Group Files of the Current Population Survey from 1994 to 2004, and the Legalized Population Survey (LPS). We find that low levels of education and wealth explain the entire gap between Mexican immigrants and non-Latino whites in business formation rates. Nearly the entire gap in business income for Mexican immigrants is explained by low levels of education and limited English language ability. Using the natural experiment created by the Immigration Reform and Control Act (IRCA), we find that legal status represents an additional barrier for Mexican immigrants. A conservative estimate suggests that the lack of legal status reduces business ownership rates by roughly seven-tenths of a percentage point for both men and women. Human and financial capital deficiencies are found to limit business ownership and business success among second and third-generation Mexican-Americans, but to a lesser extent. These findings have implications for the debates over the selection of immigrants and the assimilation of Mexican-Americans in the U.S. economy.Mexican-Americans, entrepreneurship, self-employment

The local structure of SO2 and SO3 on Ni(1 1 1): a scanned-energy mode photoelectron diffraction study

O 1s and S 2p scanned-energy mode photoelectron diffraction (PhD) data, combined with multiple-scattering simulations, have been used to determine the local adsorption geometry of the SO2 and SO3 species on a Ni(1 1 1) surface. For SO2, the application of reasonable constraints on the molecular conformation used in the simulations leads to the conclusion that the molecule is centred over hollow sites on the surface, with the molecular plane essentially parallel to the surface, and with both S and O atoms offset from atop sites by almost the same distance of 0.65 Å. For SO3, the results are consistent with earlier work which concluded that surface bonding is through the O atoms, with the S atom higher above the surface and the molecular symmetry axis almost perpendicular to the surface. Based on the O 1s PhD data alone, three local adsorption geometries are comparably acceptable, but only one of these is consistent with the results of an earlier normal-incidence X-ray standing wave (NIXSW) study. This optimised structural model differs somewhat from that originally proposed in the NIXSW investigation

Safety Procedures in the Operation of Senile Cataract

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GROWTH AND NUTRITION OF LEBANESE CHILDREN

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72514/1/j.1753-4887.1965.tb02094.x.pd

USING VIDEO BASED INSTRUCTION TO TEACH ART TO STUDENTS WITH AUTISM SPECTRUM DISORDER

Students with Autism Spectrum Disorders often do not respond to common pedagogical strategies and traditional in vivo teaching approaches. From my observations, students diagnosed with Autism Spectrum Disorders learn best when material is presented through technology. Based on the information found in the literature review and personal observations from working with students with special needs, when students with Autism Spectrum Disorders receive video based instruction by watching recorded art lessons, they may learn to develop artistic skills and retain more art content knowledge with greater success than through traditional teaching methods. The purpose of this research study is to test the hypothesis that video based teaching methods can improve the learning of students with autism in a series of art lessons

Letter from George W. Woodruff to [Theodore Roosevelt], 1907 Sep 18.

Copy)DOM DEPARTMENT OF THE INTERIOR, WASHINGTON.W. B. A.September 18, 1907.THE PRESIDENT:Tour letter of the 16th instant has been received, enclosing a communication from Mr. John Muir protesting against the projects for storage reservoirs for the San Francisco water-supply in the Yosemite National Park, and requesting a report thereon.In response thereto, I have the honor to state that a communication was received at this Department from Mr. Muir on the 12th instant on the same subject, and he was advised on the 14th that the matter would be presented to the Secretary on his return to the city about October 1st. He was further informed that, at a hearing on the application of the City of San Francisco for water from the Tuolumne River and a reservoir site in the Hetch Hetchy Valley, Yosemite National Park, held in San Francisco July 24, 1907, it was agreed by those in favor of, as well as by those opposed to the granting of the application, to submit briefs on the subject for the consideration of the Secretary. These briefs have now been received, and will be prepared for the consideration of the Secretary on his return to the city.Mr. Muir\u27s letter and accompanying enclosure are herewith returned.Very respectfully,(Signed)GEORGE W. WOODRUFFActing Secretary.CC - P&RE.M.D.0623