70,056 research outputs found

    Supersymmetry and Supercoherent States of a Nonrelativistic Free Particle

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    Coordinate atypical representation of the orthosymplectic superalgebra osp(2/2) in a Hilbert superspace of square integrable functions constructed in a special way is given. The quantum nonrelativistic free particle Hamiltonian is an element of this superalgebra which turns out to be a dynamical superalgebra for this system. The supercoherent states, defined by means of a supergroup displacement operator, are explicitly constructed. These are the coordinate representation of the known atypical abstract super group OSp(2/2)OSp(2/2) coherent states. We interpret obtained results from the classical mechanics viewpoint as a model of classical particle which is immovable in the even sector of the phase superspace and is in rectilinear movement (in the appropriate coordinate system) in its odd sector

    Assessing, valuing and protecting our environment- is there a statistical challenge to be answered?

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    This short article describes some of the evolution in environmental regulation, management and monitoring and the information needs, closely aligned to the statistical challenges to deliver the evidence base for change and effect

    African American English And Urban Literature: Creating Culturally Caring Classrooms

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    Language and literacy are a means of delivering care through consideration of students’ home culture; however, a cultural mismatch between the predominantly white, female educator population and the diverse urban student population is reflected in language and literacy instruction. Urban curricula often fail to incorporate culturally relevant literature, in part due to a dearth of texts that reflect student experiences. Dialectal differences between African American English (AAE) and Mainstream American English (MAE) and a history of racism have attached a reformatory stigma to AAE and its speakers. The authors assert that language and literacy instruction that validates children’s lived experience mediates this hegemony, leads to empathetic relationships between teachers and students of different cultural backgrounds, and promotes academic success. This paper seeks to 1) dissect the relationship between academic achievement and affirmation of student culture through language and literacy instruction, 2) enumerate classroom strategies that empower students and foster the development of self-efficacy 3) identify ways teachers might weave value for diversity in language and literacy into a pedagogy of care for urban classrooms

    Centrifugal pumps for rocket engines

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    The use of centrifugal pumps for rocket engines is described in terms of general requirements of operational and planned systems. Hydrodynamic and mechanical design considerations and techniques and test procedures are summarized. Some of the pump development experiences, in terms of both problems and solutions, are highlighted

    Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components Quarterly progress report, Jul. 1 - Sep. 30, 1968

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    Dry heat inactivation of bacterial spores and influence of spore moisture content on z values as related to spacecraft sanitatio

    Improvement of maneuver aerodynamics by spanwise blowing

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    Spanwise blowing was used to test a generalized wind-tunnel model to investigate component concepts in order to provide improved maneuver characteristics for advanced fighter aircraft. Primary emphasis was placed on performance, stability, and control at high angles of attack and subsonic speeds. Test data were obtained in the Langley high speed 7 by 10 foot tunnel at free stream Mach numbers up to 0.50 for a range of model angles of attack, jet momentum coefficients, and leading and trailing edge flap deflection angles. Spanwise blowing on a 44 deg swept trapezoidal wing resulted in leading edge vortex enhancement with subsequent large vortex induced lift increments and drag polar improvements at the higher angles of attack. Small deflections of a leading edge flap delayed these lift and drag benefits to higher angles of attack. In addition, blowing was more effective at higher Mach numbers. Spanwise blowing in conjunction with a deflected trailing edge flap resulted in lift and drag benefits that exceeded the summation of the effects of each high lift device acting alone. Asymmetric blowing was an effective lateral control device at the higher angles of attack

    Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

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    The experiments conducted to determine the heat resistance of Bacillus megaterium ATCC 6458 at 90 and 100 C were completed. Estimates from replicate experiments at eight percent relative humidities (less than 0.001 to 100% RH) for each temperature were computed. A Bacillus cereus strain with high heat resistance was cultured and the resistance determined in phosphate buffer (D sub 121.1 = 2.16 min and z = 8.7 C). The profile of the dry heat resistance of B. megaterium is summarized and the most resistant condition to the three spores (Bacillus subtilis var. niger, ATCC 29669, and Bacillus stearothermophilus, strain 1518) is compared

    Theoretical aerodynamics of upper-surface-blowing jet-wing interaction

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    A linear, inviscid subsonic compressible flow theory is formulated to treat the aerodynamic interaction between the wing and an inviscid upper-surface-blowing (USB) thick jet with Mach number nonuniformity. The predicted results show reasonably good agreement with some available lift and induced-drag data. It was also shown that the thin-jet-flap theory is inadequate for the USB configurations with thick jet. Additional theoretical results show that the lift and induced drag were reduced by increasing jet temperature and increased by increasing jet Mach number. Reducing jet aspect ratio, while holding jet area constant, caused reductions in lift, induced drag, and pitching moment at a given angle of attack but with a minimal change in the curve of lift coefficient against induced-drag coefficient. The jet-deflection effect was shown to be beneficial to cruise performance. The aerodynamic center was shifted forward by adding power or jet-deflection angle. Moving the jet away from the wing surface resulted in rapid changes in lift and induced drag. Reducing the wing span of a rectangular wing by half decreased the jet-circulation lift by only 24 percent at a thrust coefficient of 2

    Theoretical predictions of jet interaction effects for USB and OWB configurations

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    A wing jet interaction theory is presented for predicting the aerodynamic characteristics of upper surface blowing and over wing blowing configurations. For the latter configurations, a new jet entrainment theory is developed. Comparison of predicted results with some available data showed good agreement. Some applications of the theory are also presented

    Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

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    Dry heat treatment is specified as the preferred means for the terminal sterilization of spacecraft and for decontamination of spacecraft components. The presence of organisms highly resistant to dry heat in soil and fallout around assembly and industrial manufacturing areas is shown. The dry heat survival characteristics of the Cape Kennedy isolate 4-6 B. brevis spores is demonstrated. The presence of hardy organisms from soil samples obtained from geographical areas of the United States is shown. A resistant fraction appears to occur in low numbers in a soil sample. The heat resistance characteristics of 4-6 B. brevis and B. subtilis var. niger spores are compared. Their morphological characteristics are compared by scanning electron microscopy
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