Note: This page contains sample records for the topic toivo univer ao from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

La matiere noire dans l'Univers.  

NASA Astrophysics Data System (ADS)

Parmi les mille questions que l'on peut se poser sur l'Univers, les plus fondamentales concernent son contenu : De quoi est faite la matière de l'Univers ? Est-ce que la matière de l'Univers est principalement constituée d'étoiles, ou bien de gaz interstellaire, de poussières interstellaires, de planètes, petits astéroïdes, ou de trous noirs ? Ou doit-on admettre que l'Univers est composé d'une autre forme de matière que l'on ne connaît pas, qui serait basée sur des particules élémentaires plus exotiques que les protons, neutrons et électrons qui constituent la matière ordinaire, dite baryonique?

Mamon, G.

2

Les couleurs de l'Univers  

NASA Astrophysics Data System (ADS)

À quoi ressemble la Voie lactée dans l'ultraviolet ? Que cachent les nuages de poussière qui voilent des parties entières du ciel ? Avec la découverte des ondes électromagnétiques (ondes radio, ultraviolet, infrarouge, rayons X, gamma), le ciel s'est teinté de nouvelles couleurs, changeant totalement d'aspect, jusqu'à révéler des phénomènes d'une violence insoupçonnée. Les télescopes du monde entier obtiennent maintenant des images d'un univers inconnu que l'auteur nous apprend à comprendre. Riche en anecdotes parfois cocasses sur des découvertes qui doivent parfois au hasard ou à la persévérance obstinée de chercheurs, le livre invite le lecteur à découvrir un monde invisible à l'oeil. Des mystérieux quasars au rayonnement cosmologique, c'est à un voyage au fil de ce nouvel arc-en-ciel que nous convie l'auteur.

Nazé, Yaël

2005-10-01

3

52. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

52. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. MILNER TUNNEL CLOSURE GATES AND GROUP. GROUP ON GATE PLATFORM JUST BEFORE LOWERING GATES. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

4

Jayant Narlikar : dernier rempart de l'Univers stationnaire  

NASA Astrophysics Data System (ADS)

"Travailler dans une seule direction ne prouve pas que cela soit la bonne". L'astrophysicien indien, Jayant Narlikar prone la diversité des approches en recherche fondamentale - c'est bien le moins pour ce tenant de l'Univers stationnaire, théorie alternative à celle du Big Bang. Mais, selon lui, une telle démarche devient rare en cosmologie, malheureusement.

Bonnet-Bidaud, J. M.

2005-04-01

5

47. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

47. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. MILNER DAM; RIP-RAPPED UPPER SLOPE OF CENTER DAM; CROWD ALONG CHANNEL TO TUNNELS. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

6

72. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

72. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. CONTRACTOR'S DAM BELOW MILNER DAM USED TO RAISE WATER TO POWER DITCH. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

7

86. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

86. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, date unknown. ROCK CREEK SIPHON, TWIN FALLS COUNTY, SOUTH OF KIMBERLY, IDAHO; MEN WORKING ON THE EAST END OF THE SIPHON. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

8

85. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

85. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, date unknown. ROCK CREEK SIPHON, TWIN FALLS COUNTY, SOUTH OF KIMBERLY, IDAHO; EAST VIEW OF SIPHON PIPE. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

9

87. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

87. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, date unknown. ROCK CREEK SIPHON, LOW LINE CANAL, TWIN FALLS COUNTY, SOUTH OF KIMBERLY, IDAHO; UPPER END OF THE SIPHON. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

10

84. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

84. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, date unknown. ROCK CREEK SIPHON, TWIN FALLS COUNTY, SOUTH OF KIMBERLY, IDAHO; WEST VIEW OF SIPHON PIPE. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

11

83. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

83. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, date unknown. DRY CREEK GATES, TWIN FALLS COUNTY, SOUTH OF MURTAUGH, IDAHO; GATES FROM THE LOWER SIDE. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

12

81. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

81. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, date unknown. DRY CREEK DAM, TWIN FALLS COUNTY, SOUTH OF MURTAUGH, IDAHO; DRIVING SHEET PILING TO SHUT OFF SEEPAGE. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

13

82. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

82. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, date unknown. DRY CREEK HEADGATES, TWIN FALLS COUNTY, SOUTH OF MURTAUGH, IDAHO; CHECK GATES ACROSS THE MAIN CANAL BELOW DRY CREEK. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

14

48. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

48. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. MILNER DAM; WEST VIEW ACROSS DAM FROM MIDDLE DAM; SNAKE RIVER EXITING FROM TUNNELS. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

15

59. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

59. Photocopy of Photograph (original located in Univ. of Denver collection) C.R. Savage, Photographer, date unknown. MILNER DAM; TUNNEL OUTLETS WITH SNAKE RIVER PASSING THROUGH. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

16

70. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

70. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. SNAKE RIVER SHALLOWS AFTER TUNNEL CLOSURE; DOWNSTREAM FROM MILNER DAM. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

17

75. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

75. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. SNAKE RIVER GOING DRY AT MILNER. POWER DITCH AT RIGHT; RIVER IN POOLS FOLLOWING GATE CLOSURE. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

18

50. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

50. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. MILNER DAM TUNNELS. CHANNEL APPROACHING TUNNELS; SNAKE RIVER PASSING THROUGH. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

19

45. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

45. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March 1905. SNAKE RIVER BEHIND MILNER DAM; MILNER RESERVOIR RISING. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

20

64. Photocopy of Photograph (original located in Univ. of Denver ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

64. Photocopy of Photograph (original located in Univ. of Denver collection). C.R. Savage, Photographer, March, 1905. MILNER DAM. WATER FLOODING OVER SPILLWAY FOR FIRST TIME. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

21

MOND : la nouvelle théorie de l'Univers  

NASA Astrophysics Data System (ADS)

La théorie du Big Bang est face à un dilemme. Ses équations semblent parfaites mais les "ingrédients" auxquels celles-ci font appel demeurent pour l'instant totalement hypothétiques... Ils ont pour nom "matière noire" et "énergie noire" et ne représenteraient pas moins de 95% de l'Univers. Dans cette situation de "crise", une théorie élaborée en 1983, revient sur le devant de la scène. Il s'agit de MOND, une modification de la gravitation imaginée par l'israëlien Mordeghai Milgrom, qui élimine au moins une partie de ces ingrédients de nature inconnue. Même si elle doit être encore validée par des observations, sa résurrection symbolise le besoin, pour les cosmologistes, de trouver de nouvelles voies pour décrire l'Univers.

Bonnet-Bidaud, J. M.

2006-12-01

22

A Needs Assessment for the Introduction of a Food Science Program at the Univ. of Guyana  

ERIC Educational Resources Information Center

This research describes the outcome of a needs assessment to determine whether the Univ. of Guyana should introduce a Food Science program. The research design utilized interviews and questionnaires to large manufacturing organizations and agroprocessors to determine if the required skills are available for the manufacturing process. Results…

Morrison, Donna

2012-01-01

23

Flow resistances of disposable double-lumen, single-lumen, and univent tubes  

Microsoft Academic Search

Objective: To compare the airflow resistances of modern double-lumen, single-lumen, and Univent (Fuji Systems Corp; Tokyo, Japan) tubes.Design: A laboratory bench study.Setting: A university hospital laboratory.Measurements: Pressure differentials (Pd) were measured across study tubes at 10 L\\/min airflow (V?) increments from 0 to 60 L\\/min in a tracheal model. Coefficients of resistance k1 (linear) and k2 (nonlinear) were calculated for

Peter D. Slinger; Lawrence Lesiuk

1998-01-01

24

Signature de divers Modèles d'Univers primordial dans les Anisotropies du Rayonnement fossile  

NASA Astrophysics Data System (ADS)

Cette thèse porte sur l'étude de divers modèles d'Univers primordial et leur observabilité dans les anisotropies du rayonnement fossile. Dans la première partie sont exposées les équations d'évolution des perturbations cosmologiques. On y fait un rappel de la physique du rayonnement fossile, et l'influence des différents paramètres cosmologiques y est présentée. Les trois parties suivantes s'intéressent à différents scénarios d'Univers primordial.La deuxième partie porte sur les scénarios à base de sources actives, dont font partie les défauts topologiques. Les différences majeures avec les scénarios inflationnaires y sont exposées. On y détaille l'importance des effets non linéaires dans l'évolution des sources et de leurs interactions non gravitationnelles avec le reste de l'Univers. La troisième partie porte sur les scénarios inflationnaires, et discute les hypothèses habituellement faites à propos de l'état des perturbations en fin d'inflation. L'accent est mis sur l'importance de la modélisation de ces conditions initiales pour pouvoir extraire des informations précises sur les paramètres cosmologiques à partir des observations des anisotropies du rayonnement fossile. Enfin, la quatrième partie porte sur les scénarios de quintessence, et notamment sur l'influence de ce champ scalaire sur la dynamique des perturbations cosmologiques. Il est montré que ces modèles font des prédictions assez différentes des scénarios avec constante cosmologique.

Riazuelo, Alain

2000-12-01

25

Univers: The construction of an internet-wide descriptive naming system  

NASA Technical Reports Server (NTRS)

Descriptive naming systems allow clients to identify a set of objects by description. Described here is the construction of a descriptive naming system, called Univers, based on a model in which clients provide both an object description and some meta-information. The meta-information describes beliefs about the query and the naming system. Specifically, it is an ordering on a set of perfect world approximations, and it describes the preferred methods for accommodating imperfect information. The description is then resolved in a way that respects the preferred approximations.

Bowman, C. Mic

1990-01-01

26

Histoire du télescope, la contemplation de l'Univers, des premiers instruments aux actuelles machines célestes  

NASA Astrophysics Data System (ADS)

Alors que la plupart des scientifiques réalisent leurs expérimentations en laboratoire, les astronomes sont condamnés à ne jamais pouvoir toucher l'objet de leurs travaux: le ciel se laisse contempler mais demeure hors d'atteinte. Pour déchiffrer le message céleste, l'oeil ne suffit pas. Il fallut attendre la naissance de la première lunette astronomique pour ouvrir une nouvelle voie à notre insatiable désir de savoir. Ancêtre de tous les télescopes petits et grands, ce tout premier instrument d'observation allait en effet étendre vers l'infini le pouvoir de nos yeux. Quatre cents ans après, ce sont d'immenses machines qui scrutent pour nous l'Univers, en nous permettant même de remonter le temps. C'est leur histoire qui nous est racontée ici mais, par deçà les engins les plus complexes, ce livre nous parle de leurs bâtisseurs. Démontant au passage certaines idées reçues, ce livre nous plonge dans les balbutiements de ces instruments avant de nous emmener côtoyer les premiers géants et découvrir les révolutions en cours. Illustré de nombreux documents historiques et techniques, ce récit est également pourvu d'encadrés expliquant en profondeur le fonctionnement des instruments.

Nazé, Yaël

2009-01-01

27

Cometas: Das Lendas aos Fatos  

NASA Astrophysics Data System (ADS)

O descobrimento de cometas, devido ao seu aparecimento espetacular, tem registro nas mais antigas culturas humanas. A primeira referência situa-se no ano de 1095 antes de Cristo [a.C.; HO; HO, 1962]. A quantidade de registros de descobrimentos cometários, principalmente provenientes do território chinês em particular e do oriente em geral, aumentou gradualmente a partir do quarto século depois de Cristo (d.C.). É de origem chinesa a primeira referência ao cometa P/Halley no ano de 240 a.C. [VOELZKE, 1993]. Com o desenvolvimento da astronomia relativamente às técnicas observacionais os descobrimentos bem como as observações cometárias aumentaram sensivelmente a partir do século XVII, sendo que a partir do século XIX um novo incremento ocorreu devido ao emprego da fotografia e a resultante melhora de sensibilidade na observação.

Voelzke, M. R.

28

Experiments on the nuclear interactions of pions and electrons. [Dept. of Physics, Univ. of Virginia  

SciTech Connect

The analysis of the deuterium content in the CD target used in an experiment to study the [pi] + d [yields] 2p reaction at incident pion energies from 4 to 20 MeV was completed. The final paper describing this experiment will be submitted for publication this summer. Analysis of LAMPF Exp. on pion absorption in [sup 4]He is continuing. In 1991, we collaborated with D. Pocanic from the Univ. of Virginia on a measurement at LAMPF of the [pi][sup 0] production in [pi] + p interactions. This run proved the validity of the method and additional data were obtained in a second run during the summer of 1992, using a new target. Current collaborations at LAMPF include the search for the decay [mu][sup +] [yields] e[sup +] + [gamma](MEGA) and a measurement of the Michel [rho] parameter in the decay [mu] [yields] e + v + v. A U.Va.--PSI collaboration is measuring pion beta decay to an accuracy of less than 1%, using a large acceptance CsI detector to measure the [pi][sup 0] following decay of stopped [pi][sup +] mesons. Most of the U.Va. effort is devoted to the CEBAF Large Acceptance Spectrometer (CLAS) program to the construction of the CLAS forward calorimeter. An apparatus to measure the properties of the scintillators with light from a N[sub 2] laser was built in the spring of 1992. The electronic circuitry for the energy signal from the EGN detector and the circuitry needed to route the signals from the all the photomultipliers to the TDC and ADC circuits are being developed. Experimental proposals for the study of electroproduction of nucleon resonances at CEBAF, including measurements with polarized beam and targets, are being developed.

Minehart, R.C.; Ziock, K.O.H.

1992-08-01

29

MEMS AO for Planet Finding  

NASA Technical Reports Server (NTRS)

This slide presentation reviews a method for planet finding using microelectromechanical systems (MEMS) Adaptive Optics (AO). The use of a deformable mirror (DM) is described as a part of the instrument that was designed with a nulling interferometer. The strategy that is used is described in detail.

Rao, Shanti; Wallace, J. Kent; Shao, Mike; Schmidtlin, Edouard; Levine, B. Martin; Samuele, Rocco; Lane, Benjamin; Chakrabarti, Supriya; Cook, Timothy; Hicks, Brian; Jung, Paul

2008-01-01

30

Aerosol Observing System (AOS) Handbook  

SciTech Connect

The Aerosol Observing System (AOS) is a suite of in situ surface measurements of aerosol optical and cloud-forming properties. The instruments measure aerosol properties that influence the earth’s radiative balance. The primary optical measurements are those of the aerosol scattering and absorption coefficients as a function of particle size and radiation wavelength and cloud condensation nuclei (CCN) measurements as a function of percent supersaturation. Additional measurements include those of the particle number concentration and scattering hygroscopic growth. Aerosol optical measurements are useful for calculating parameters used in radiative forcing calculations such as the aerosol single-scattering albedo, asymmetry parameter, mass scattering efficiency, and hygroscopic growth. CCN measurements are important in cloud microphysical models to predict droplet formation.

Jefferson, A

2011-01-17

31

Tricorrectional bunionectomy with AO screw fixation.  

PubMed

A 16-month preliminary study was performed on 58 patients for corrective surgery of hallux abducto valgus, with AO4 screw fixation. The procedure is a modification of the bi-plane Austin procedure, called a tricorrectional bunionectomy. The authors present the procedure with objective and subjective findings. The principles of bone healing and internal fixation using AO screw fixation are discussed. PMID:2625507

Boggs, S I; Selner, A J; Roth, I E; Bernstein, A L

1989-01-01

32

Experimental study on the thorium-loaded accelerator-driven system at the Kyoto Univ. critical assembly  

SciTech Connect

The experimental study on the thorium-loaded accelerator-driven system (ADS) is conducted in the Kyoto Univ. Critical Assembly (KUCA). The experiments are carried out in both the critical and subcritical states for attaining the reaction rates of the thorium capture and fission reactions. In the critical system, the thorium plate irradiation experiment is carried out for the thorium capture and fission reactions. From the results of the measurements, the thorium fission reactions are obtained apparently in the critical system, and the C/E values of reaction rates show the accuracy of relative difference of about 30%. In the ADS experiments with 14 MeV neutrons and 100 MeV protons, the subcritical experiments are carried out in the thorium-loaded cores to obtain the capture reaction rates through the measurements of {sup 115}In(n, {gamma}){sup 116m}In reactions. The results of the experiments reveal the difference between the reaction rate distributions for the change in not only the neutron spectrum but also the external neutron source. The comparison between the measured and calculated reaction rate distributions demonstrates a discrepancy of the accuracy of reaction rate analyses of thorium capture reactions through the thorium-loaded ADS experiments with 14 MeV neutrons. Hereafter, kinetic experiments are planned to be carried out to deduce the delayed neutron decay constants and subcriticality using the pulsed neutron method. (authors)

Pyeon, C. H.; Yagi, T.; Lim, J. Y.; Misawa, T. [Nuclear Science Engineering Div., Research Reactor Inst., Kyoto Univ., Asashiro-nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

2012-07-01

33

The New Frontiers Academic AO Experiment  

NASA Astrophysics Data System (ADS)

The University of Alabama in Huntsville and the College of Charleston have embarked on an educational experiment called the Academic AO Project. This project seeks to simulate the NASA Announcement of Opportunity response process in the classroom.

Benfield, M. P. J.; Turner, M. W.; Runyon, C. J.; Hakkila, J.

2010-03-01

34

The Magellan Telescope adaptive secondary AO system  

NASA Astrophysics Data System (ADS)

The Magellan Clay telescope is a 6.5m Gregorian telescope located in southern Chile at Las Campanas Observatory. The Gregorian design allows for an adaptive secondary mirror that can be tested off-sky in a straight-forward manner. We have fabricated a 85 cm diameter aspheric adaptive secondary with our subcontractors and partners. This secondary has 585 actuators with <1 msec response times. The chopping adaptive secondary will allow low emissivity AO science. We will achieve very high Strehls (~98%) in the Mid-IR AO (8-26 microns) with the BLINC/MIRAC4 Mid-IR science camera. This will allow the first "super-resolution" and nulling Mid-IR studies of dusty southern objects. We will employ a high order (585 mode) pyramid wavefront sensor similar to that used in the Large Binocular Telescope AO systems. The relatively high actuator count will allow modest Strehls to be obtained in the visible (~0.8?m). Our visible light AO (Vis AO) science camera is fed by an advanced ADC and beamsplitter piggy-backed on the WFS optical table. The system science and performance requirements, and an overview the design, interface and schedule for the Magellan AO system are presented here.

Close, Laird M.; Gasho, Victor; Kopon, Derek; Hinz, Phil M.; Hoffmann, William F.; Uomoto, Alan; Hare, Tyson

2008-07-01

35

Standard Triaxial Ellipsoid Asteroids from AO Observations  

NASA Astrophysics Data System (ADS)

As part of our study of resolved asteroids using adaptive optics (AO) on large telescopes (>8; m), we have identified several that can serve as Standard Triaxial Ellipsoid Asteroids (STEAs), suitable for radar and thermo-physical calibration. These objects are modeled well as triaxial ellipsoids, having: 1) small uncertainties on their three dimensions as determined with AO; 2) rotational poles well determined from both lightcurves and AO; and 3) good sidereal periods from lightcurves. Although AO allows the opportunity to find an asteroid's dimensions and rotational pole in one night, we have developed a method to combine AO observations from different oppositions to pool into a global solution. The apparent orientation and sizes of STEAs can be predicted to within a few degrees and a few km over decades. Currently, we consider 511 Davida, 52 Europa, 2 Pallas, and 15 Eunomia as STEAs. Asteroids that are not well modeled as ellipsoids, clearly showing departures from ellipsoid figures in AO images, include 129 Antigone and 41 Daphne. We will show movies of images and models of these asteroids.

Drummond, Jack D.; Merline, W. J.; Conrad, A.; Dumas, C.; Carry, B.

2008-09-01

36

Characterization of an AO-OCT system  

SciTech Connect

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-volumetric-resolution, images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging [1]. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction [2] and a 140-actuator Boston Micromachines DM for high-order correction [3]. We are beginning to investigate the potential for increasing the image contrast in this system using higher-order wavefront correction. The first step in this analysis is to quantify the residual wavefront error (WFE) in the current system. Developing an error budget is a common tool for improved performance and system design in astronomical AO systems [4, 5]. The process for vision science systems is also discussed in several texts e.g. [6], but results from this type of analysis have rarely been included in journal articles on AO for vision science. Careful characterization of the AO system will lead to improved performance and inform the design of a future high-contrast system. In general, an AO system error budget must include an analysis of three categories of residual WFE: errors in measuring the phase, errors caused by limitations of the DM(s), and errors introduced by temporal variation. Understanding the mechanisms and relative size of these errors is critical to improving system performance. In this paper we discuss the techniques for characterizing these error sources in the AO-OCT system. It is useful to first calculate an error budget for the simpler case using a model eye, and then add the additional errors introduced for the case of a human subject. Measurement error includes calibration error, wavefront sensor (WFS) CCD noise, and sampling errors. Calibration errors must be measured by an external system. Typically this error is inferred from measurements of the point spread function (PSF). It can also be estimated by measuring known wavefront errors and comparing to the WFS measurement. Both methods will be used in the AO-OCT system. In this particular system measurement error introduced by the WFS can be caused by low light levels, poor camera sensitivity at the operating wavelength and noise introduced by heat in the uncooled CCD. Also, the gaussian beam profile of the system causes centroids near the edges of the pupil to be dimmer, and thus noisier. The easiest way to estimate measurement error is to compare successive wavefront measurements when the system is stable. This techniques will include vibrations and other systematic errors. Alternatively the measurement error can be estimated from measured signal to noise. This is more complicated but will decouple measurement errors from stability measurements. Ultimately, even if the phase is measured perfectly, performance will still be limited by the fitting error [7]. This error is inversely proportional to the number of actuators of the DM. Basically wavefront errors with spatial frequencies greater than half the number of actuators across the aperture cannot be corrected. For DMs with modal influence functions (like the AOptix Bimorph in the AO-OCT system), this translates to the number of modes which can be corrected. The AO-OCT system over-samples the wavefront, so to some extent, we can measure these out-of-band errors directly. In addition to fitting error, the DM will introduce errors based on the ability of each individual actuator to go to the position demanded by the control system. Generally this voltage step size is limited by the resolution of the drive electronics and can be calculated analytically.

Evans, J W; Zawadzki, R J; Jones, S; Olivier, S; Werner, J S

2007-07-26

37

UnivUtah  

Cancer.gov

Post-Doctoral Fellow needed for projects examining how the family system can be a vehicle for the promotion of health and dealing with chronic illnesses across the life span as part of a consortium on Life-Span Health within the Family System. The fellow would work with an interdisciplinary team of investigators across the Departments of Psychology, Pediatrics, Physical Therapy, Family and Consumer Studies, Sociology, Center on Aging, and Huntsman Cancer Institute.

38

Experimental comparison of Wide Field AO control schemes using the Homer AO bench.  

NASA Astrophysics Data System (ADS)

Wide Field Adaptive Optics (WFAO) concepts, such as Laser Tomography AO (LTAO) or Multi-Conjugate AO (MCAO) have been developed in order to overcome the anisoplanatism limit of classical AO. Most of the future AO-assisted instruments of ELTs rely on such concepts which have raised critical challenges such as tomographic estimation and from laser and natural guide star combined with efficient DM(s) control. In that context, the experimental validation of the various clever control solutions proposed by several teams in the past years is now essential to reach a level of maturity compatible with their implementation in future WFAO developments for ELT. The ONERA wide field AO facility (HOMER bench) has been developed for these very issues. Gathering a 3D turbulence generator, laser and natural guide stars, two deformable mirrors with variable altitude positions and a PC-based flexible and user-friendly RTC , HOMER allows the implementation and comparison of control schemes from the simplest least-square to the optimal Linear Quadratic Gaussian solutions including Virtual DM and Pseudo-closed loop approaches. After a description of the bench internal calibrations and ultimate performance, all the control schemes are compared experimentally. Their evolutions as a function of wavefront sensors SNR as well as their robustness to calibration / model errors are particularly emphasised. Finally, we derive from the previous works some specific calibrations and identifications procedures ensuring both robustness and efficiency of WFAO systems and we extrapolate their applications to the future ELT AO systems.

Parisot, Amélie; Petit, Cyril; Fusco, Thierry

2011-09-01

39

The first VisAO-fed integral field spectrograph: VisAO IFS  

NASA Astrophysics Data System (ADS)

We present the optomechanical design of the Magellan VisAO Integral Field Spectrograph (VisAO IFS), designed to take advantage of Magellan's AO system and its 85.1cm concave ellipsoidal Adaptive Secondary Mirror (ASM). With 585 actuators and an equal number of actively-controlled modes, this revolutionary second generation ASM will be the first to achieve moderate Strehl ratios into the visible wavelength regime. We have designed the VisAO IFS to be coupled to either Magellan's LDSS-3 spectrograph or to the planned facility M2FS fiber spectrograph and to optimize VisAO science. Designed for narrow field-of-view, high spatial resolution science, this lenslet-coupled fiberfed IFS will offer exciting opportunities for scientific advancement in a variety of fields, including protoplanetary disk morphology and chemistry, resolution and spectral classification of tight astrometric binaries, seasonal changes in the upper atmosphere of Titan, and a better understanding of the black hole M-sigma relation.

Follette, Katherine B.; Close, Laird M.; Kopon, Derek; Males, Jared R.; Gasho, Victor; Brutlag, Kevin M.; Uomoto, Alan

2010-07-01

40

Diferentes Metodologias Aplicadas ao Ensino de Astronomia  

NASA Astrophysics Data System (ADS)

Espera-se que o educando ao final da educação básica, adquira uma compreensão atualizada das hipóteses, modelos e formas de investigação sobre a origem e evolução do Universo em que vive. O presente trabalho tem como principal objetivo compreender dentre três práticas pedagógicas adotadas no Ensino de Astronomia, na terceira série do Ensino Médio, da Escola Estadual Colônia dos Pescadores, qual melhor cumpre o papel de formação e aprendizagem para vida. A pesquisa preliminar foi através de um questionário onde o intuito foi diagnosticar o conhecimento já existente acerca do tema em questão. O questionário é composto de vinte questões dissertativas e objetivas, onde os educandos das três turmas envolvidas o responderam. Este trabalho utiliza as seguintes metodologias: a tradicional, onde o professor é um repassador de informações, fazendo uso exclusivo de lousa e giz; a segunda também de forma tradicional, porém com auxílio de multimídia para desenvolvimento das aulas e aterceira sob forma de seminários, elaborados e apresentados pelos educandos, no qual o educador faz apenas as intervenções necessárias. Ao final do trabalho os alunos responderão novamente o questionário inicial para diagnosticar dentre as três metodologias utilizadas qual apresentou melhor resultado. Os resultados preliminares obtidos, já podem ser observados e, dos 119 alunos entrevistados, as respostas obtidas são as mais diversas e evidenciam que a grande maioria nunca teve em sua vida escolar o tema Astronomia. Ao serem questionados se já haviam estudado Astronomia as respostas foram: turma A: sim 43%; turma B: sim: 21%; turma C: sim: 24%. Porém quando questionados a respeito do significado de Astronomia observou-se que: turma A: 100% de acertos; turma B: 64% acertos; turma C: 84% de acertos, demonstrando claramente a aprendizagem em diferentes esferas, não dependendo unicamente da escola. Até o presente momento, verificou-se que há interesse em estudar o tema Astronom! ia entre os educandos.

Albrecht, E.; Voelzke, M. R.

2007-08-01

41

Extreme is the new normal: lessons from 8-m ExAO for ELT regular AO  

NASA Astrophysics Data System (ADS)

The first true extreme adaptive optics (ExAO) instruments for 8-m telescopes are nearing completion - SPHERE for the Very Large Telescope, and the Gemini Planet Imager for Gemini South. With N=40 to 44 subapertures across the telescope, these high-performance systems represent an important step towards the N=60+ systems that will be needed for general-purpose AO on ELTs. GPI and SPHERE each incorporate many key technologies - high-density deformable mirrors, computationally efficient advanced wavefront control algorithms, zero-noise CCDs, multi-stage wavefront correction, new calibration algorithms, etc. - that will have to be incoprorated into the ELT facilities. We will review these features and the status of the two instruments, and the lessons learned for the design of ELT AO, both normal and extreme

Macintosh, B.; Beuzit, J.-L.

2011-09-01

42

Characterization of an AO-OCT system - Oral Paper  

NASA Astrophysics Data System (ADS)

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution, 3-D, in vivo images of the retina. We will discuss general techniques for characterizing a vision science AO system, and we will describe the results of applying these techniques to measure the residual wavefront errors for the UC Davis AO-OCT system. Careful characterization of the AO system will lead to improved performance and inform the design of future systems.

Evans, J. W.; Zawadzki, Robert J.; Jones, Steve; Olivier, Scot S.; Werner, John S.

2008-01-01

43

The Magellan Telescope Adaptive Secondary AO System: a visible and mid-IR AO facility  

NASA Astrophysics Data System (ADS)

The Magellan Clay telescope is a 6.5m Gregorian telescope located in Chile at Las Campanas Observatory. The Gregorian design allows for an adaptive secondary mirror that can be tested off-sky in a straightforward manner. We have fabricated a 85 cm diameter aspheric adaptive secondary with our subcontractors and partners, the ASM passed acceptance tests in July 2010. This secondary has 585 actuators with <1 msec response times (0.7 ms typically). This adaptive secondary will allow low emissivity AO science. We will achieve very high Strehls (~98%) in the Mid-IR (3-26 microns) with the BLINC/MIRAC4 Mid-IR science camera. This will allow the first "super-resolution" and nulling Mid-IR studies of dusty southern objects. We will employ a high order (585 mode) pyramid wavefront sensor similar to that now successfully used at the Large Binocular Telescope. The relatively high actuator count will allow modest Strehls to be obtained in the visible (0.63-1.05 ?m). Moderate (~20%) Strehls have already been obtained at 0.8 ?m at the LBT with the same powerful combination of a next generation ASM and Pyramid WFS as we are providing for Magellan. Our visible light AO (VisAO) science camera is fed by an advanced triplet ADC and is piggy-backed on the WFS optical board. We have designed an additional "clean-up" very fast (2 kHz) tilt stabilization system for VisAO. Also a high-speed shutter will be used to block periods of poor correction. The VisAO facility can be reconfigured to feed an optical IFU spectrograph with 20 mas spaxels. The entire system passed CDR in June 2009, and is now finished the fabrication phase and is entering the integration phase. The system science and performance requirements, and an overview the design, interface and schedule for the Magellan AO system are presented here.

Close, Laird M.; Gasho, Victor; Kopon, Derek; Males, Jared; Follette, Katherine B.; Brutlag, Kevin; Uomoto, Alan; Hare, Tyson

2010-07-01

44

Testing the VLT AO facility with ASSIST  

NASA Astrophysics Data System (ADS)

The testing and verification of ESO Very Large Telescope Adaptive Optics Facility (VLT-AOF) requires new and innovative techniques to deal with the absence of an intermediate focus on the telescope. ASSIST, The Adaptive Secondary Setup and Instrument STimulator, was developed to provide a testing facility for the ESO AOF and will allow off-telescope testing of three elements of the VLT Adaptive Optics Facility; the Deformable Secondary Mirror (DSM) and the AO systems for MUSE and HAWK-I (GALACSI and GRAAL). ASSIST will provide a full testing environment which includes an interferometric testing mode for the DSM, an on-axis testing mode with a single wavefront sensor and full operation testing modes for both the AO systems. Both natural as well as laser guide stars will be simulated under various asterisms and a realistic turbulent atmosphere will be provided for varying atmospheric conditions. ASSIST passed its final design review and is now being manufactured, integrated and tested and will be operational in mid 2011, in time for first testing with the DSM.

Stuik, Remko; Arsenault, Robin; Boland, Wilfried; Deep, Atul; Delabre, Bernard; Hubin, Norbert; Kolb, Johann; La Penna, Paolo; Molster, Frank; Wiegers, Emiel

2010-07-01

45

Cold Friends of Hot Jupiters: AO Survey  

NASA Astrophysics Data System (ADS)

“Hot Jupiters” are a class of gas giant planets found in extrasolar systems at very small orbital distances (?0.05 AU). We know that these planets could not have formed at their present locations, but must instead have migrated in from beyond the ice line. One class of proposed migration mechanisms for these planets involve gravitational perturbations from a distant stellar companion. These same processes also provide a natural explanation for the existence of a subset of hot Jupiters that have been observed to have orbits that are highly misaligned with respect to their star's spin axis and/or have large orbital eccentricities. In the "Cold Friends" survey, we search for stellar companions around 51 stars known to host hot Jupiters in order to determine whether stellar companions play an important role in hot Jupiter migration. Our survey consists of a population of stars with planets that have eccentric and/or misaligned orbits as well as a control population of planets with well-aligned and circular orbits. This project searches for companion stars (the "Cold Friends") in three detection modes: radial velocity monitoring, high resolution IR spectroscopy (presented by D. Piskorz et al. at this meeting), and adaptive optics (AO) imaging at infrared wavelengths (presented here). The AO mode is sensitive to the most distant companions (separations of 50-200 AU and beyond) while the other modes are effective at finding companions at smaller separations. We present the results of our AO survey and discuss the binary fraction found in our sample. Out of our total sample of 51 stars, 19 candidate companions (many of which have not been observed before) were directly imaged around 17 stars. We also describe follow-up photometry and astrometry of all detected companions to determine whether or not they are gravitationally bound to the primary planet-hosting star. If such companions are common, it would suggest that perturbations from stellar companions may play a significant role in the evolution of hot Jupiter systems.

Ngo, Henry; Knutson, H. A.; Hinkley, S.; Crepp, J. R.; Batygin, K.; Howard, A. W.; Johnson, J. A.; Morton, T. D.; Muirhead, P. S.

2013-10-01

46

Electromagnetic DM technology meets future AO demands  

NASA Astrophysics Data System (ADS)

New deformable mirror technology is developed by the Technische Universiteit Eindhoven, Delft University of Technology and TNO Science and Industry. Several prototype adaptive deformable mirrors are realized mirrors, up to 427 actuators and ?150mm diameter, with characteristics suitable for future AO systems. The prototypes consist of a 100µm thick, continuous facesheet on which low voltage, electromagnetic, push-pull actuators impose out-of-plane displacements. The variable reluctance actuators with ±10µm stroke and nanometer resolution are located in a standard actuator module. Each module with 61 actuators connects to a single PCB with dedicated, 16 bit, PWM based, drivers. A LVDS multi-drop cable connects up to 32 actuator modules. With the actuator module, accompanying PCB and multi-drop system the deformable mirror technology is made modular in its mechanics and electronics. An Ethernet-LVDS bridge enables any commercial PC to control the mirror using the UDP standard. Latest results of the deformable mirror technology development are presented.

Hamelinck, Roger; Rosielle, Nick; Steinbuch, Maarten; Doelman, Niek

47

AO SLM demonstration system and test bed  

NASA Astrophysics Data System (ADS)

In order to demonstrate and to quantitatively evaluate the wavefront correction capabilities of a spatial light modulator (SLM) for optical imaging enhancement in Adaptive Optics (AO) a compact and flexible demonstration system and test bed has been developed. It basically consists of a projection system, where image objects of different complexity and spatial resolution can be implemented and imaged through Adaptive Optics onto a CCD camera. Furthermore, static and dynamic wavefront errors of different severeness can be introduced by means of fixed and rotating phase plates. With this system for the first time the optical performance of the Fraunhofer IPMS 240 × 200 micro mirror SLM for highresolution wavefront control has been characterized. For an incoherent or partially coherent imaging as employed in this case the image quality normally is assessed in terms of the Modulation Transfer Function (MTF). Therefore, a quantitative evaluation has been carried out by measuring the system MTF including the SLM for a number of spatial frequencies as well as for a variety of different complex aberrations without and with applied correction. Besides a description of the system set-up the obtained results on the imaging improvement and MTF measurement are presented.

Wildenhain, Michael; Knobbe, Jens; Gehner, Andreas; Wagner, Michael; Lakner, Hubert

2007-03-01

48

NFIRAOS Multiconjugate AO System for TMT  

NASA Astrophysics Data System (ADS)

NFIRAOS, the Adaptive Optics system for the Thirty Meter Telescope, is a Multiconjugate Adaptive Optics System of order 60x60 with two deformable mirrors and six laser guide star wavefront sensors. NFIRAOS is 8 x 10 x 5 m (L x W x H) on a Nasmyth Platform and supports three client instruments operating over 0.8 - 2.5 ?m wavelength range. In this paper we discuss: NFIRAOS' requirements and architecture; changes to NFIRAOS since the last AO4ELT conference; interior details of NFIRAOS; interfaces to instruments; integration and verification plans. Top-level science requirements include 50% sky coverage at the galactic pole with <187 nm wavefront error. Astrometry is an important science driver - to minimize image distortion, we have recently revised the optical design to use four off-axis paraboloidal mirrors. We have vastly simplified the laser WFS zoom optics and moved them inside the cold enclosure. To control image magnification, differential magnification and tip/tilt/focus, NFIRAOS' client instruments have three low-order warfront sensors monitoring near-infrared natural guide stars. These stars are sharpened by NFIRAOS, which assists sky coverage. NFIRAOS will have high throughput and low thermal background - it will be cooled to -30 °C. The insulated walls have a buried cold plate to intercept heat leakage and isothermalize the interior of NFIRAOS. Instruments have stringent requirements on heat leakage and must provide their own rotator and interface to NFIRAOS, including a rotating seal. For wavelength and flat field calibration of client instruments, a NFIRAOS Science Calibration Unit (NSCU) feeds light in the entrance window, through NFIRAOS, to instruments. Inside NFIRAOS are deployable light sources simulating natural and laser guide stars, a focal plane mask with pinholes illuminated by the NSCU, as well as a turbulence phase screen. A prototype screen has been manufactured by magneto-rheological machining. We are currently updating the NFIRAOS preliminary design.

Herriot, Glen; Andersen, David; Atwood, Jenny; Byrnes, Peter; Boyer, Corinne; Caputa, Kris; Correia, Carlos; Dunn, Jennifer; Ellerbroek, Brent; Fitzsimmons, Joeleff; Gilles, Luc; Hickson, Paul; Hill, Alexis; Pazder, John; Reshetov, Vlad; Smith, Malcolm; Véran, Jean-Pierre; Wang, Lianqi; Wevers, Ivan

2011-09-01

49

Simulations of (MC)AO for a 100-m telescope  

Microsoft Academic Search

In this paper, we summarize the analysis made on various Adaptive Optics (AO) modes (including Shack-Hartmann (SH) and Pyramid Wavefront Sensors (PWS)) for the OverWhelmingly Large telescope (OWL). We will show some early results of the performance to be expected with a first generation AO system, working in the infrared. Several telescope diameters were considered to see the variations as

Miska Le Louarn; Christophe Verinaud; Natalia Yaitskova; Visa Korkiakoski; Enrico Fedrigo; Norbert N. Hubin

2004-01-01

50

First closed-loop visible AO test results for the advanced adaptive secondary AO system for the Magellan Telescope: MagAO's performance and status  

NASA Astrophysics Data System (ADS)

The heart of the 6.5 Magellan AO system (MagAO) is a 585 actuator adaptive secondary mirror (ASM) with <1 msec response times (0.7 ms typically). This adaptive secondary will allow low emissivity and high-contrast AO science. We fabricated a high order (561 mode) pyramid wavefront sensor (similar to that now successfully used at the Large Binocular Telescope). The relatively high actuator count (and small projected ~23 cm pitch) allows moderate Strehls to be obtained by MagAO in the “visible” (0.63-1.05 ?m). To take advantage of this we have fabricated an AO CCD science camera called "VisAO". Complete “end-to-end” closed-loop lab tests of MagAO achieve a solid, broad-band, 37% Strehl (122 nm rms) at 0.76 ?m (i’) with the VisAO camera in 0.8” simulated seeing (13 cm ro at V) with fast 33 mph winds and a 40 m Lo locked on R=8 mag artificial star. These relatively high visible wavelength Strehls are enabled by our powerful combination of a next generation ASM and a Pyramid WFS with 400 controlled modes and 1000 Hz sample speeds (similar to that used successfully on-sky at the LBT). Currently only the VisAO science camera is used for lab testing of MagAO, but this high level of measured performance (122 nm rms) promises even higher Strehls with our IR science cameras. On bright (R=8 mag) stars we should achieve very high Strehls (>70% at H) in the IR with the existing MagAO Clio2 (?=1-5.3 ?m) science camera/coronagraph or even higher (~98% Strehl) the Mid-IR (8-26 microns) with the existing BLINC/MIRAC4 science camera in the future. To eliminate non-common path vibrations, dispersions, and optical errors the VisAO science camera is fed by a common path advanced triplet ADC and is piggy-backed on the Pyramid WFS optical board itself. Also a high-speed shutter can be used to block periods of poor correction. The entire system passed CDR in June 2009, and we finished the closed-loop system level testing phase in December 2011. Final system acceptance (“pre-ship” review) was passed in February 2012. In May 2012 the entire AO system is was successfully shipped to Chile and fully tested/aligned. It is now in storage in the Magellan telescope clean room in anticipation of “First Light” scheduled for December 2012. An overview of the design, attributes, performance, and schedule for the Magellan AO system and its two science cameras are briefly presented here.

Close, Laird M.; Males, Jared R.; Kopon, Derek A.; Gasho, Victor; Follette, Katherine B.; Hinz, Phil; Morzinski, Katie; Uomoto, Alan; Hare, Tyson; Riccardi, Armando; Esposito, Simone; Puglisi, Alfio; Pinna, Enrico; Busoni, Lorenzo; Arcidiacono, Carmelo; Xompero, Marco; Briguglio, Runa; Quiros-Pacheco, Fernando; Argomedo, Javier

2012-07-01

51

Seasonality of synoptic eddy feedback and the AO/NAO  

NASA Astrophysics Data System (ADS)

In this paper, by using a dynamic model with synoptic eddy and low-frequency flow (SELF) interaction, we show that the SELF feedback is of significant importance for the formation of the AO/NAO in both winter and summer. Although background storm activity is significantly weaker in summer than that in winter, the positive SELF feedback associated with the AO/NAO mode in summer can be as strong as that in winter. The seasonal variations of the AO/NAO patterns are found to resemble those of the leading singular modes simulated by a linear dynamic system with the SELF interaction in different seasons, and the seasonal shifts in spatial patterns of the AO/NAO are the result of the seasonal changes in climatological basic state and synoptic eddy activity.

Pan, Lin-Lin; Jin, Fei-Fei

2005-11-01

52

A Large-Telescope Natural Guide Star AO System  

NASA Technical Reports Server (NTRS)

None given. From overview and conclusion:Keck Telescope case study. Objectives-low cost, good sky coverage. Approach--natural guide star at 0.8um, correcting at 2.2um.Concl- Good performance is possible for Keck with natural guide star AO system (SR>0.2 to mag 17+).AO-optimized CCD should b every effective. Optimizing td is very effective.Spatial Coadding is not effective except perhaps at extreme low light levels.

Redding, David; Milman, Mark; Needels, Laura

1994-01-01

53

Beyond the Blur: Construction and Characterization of the First Autonomous AO System, and, An AO Survey of Magnetar Proper Motions  

NASA Astrophysics Data System (ADS)

Adaptive optics (AO) corrects distortions created by atmospheric turbulence and delivers diffraction-limited images on ground-based telescopes. The vastly improved spatial resolution and sensitivity has been utilized for studying everything from the magnetic fields of sunspots upto the internal dynamics of high-redshift galaxies. This thesis about AO science from small and large telescopes is divided into two parts: Robo-AO and magnetar kinematics. In the first part, I discuss the construction and performance of the world's first fully autonomous visible light AO system, Robo-AO, at the Palomar 60-inch telescope. Robo-AO operates extremely efficiently with an overhead < 50s, typically observing about 22 targets every hour. We have performed large AO programs observing a total of over 7,500 targets since May 2012. In the visible band, the images have a Strehl ratio of about 10% and achieve a contrast of upto 6 magnitudes at a separation of 1??. The full-width at half maximum achieved is 110-130 milli-arcsecond. I describe how Robo-AO is used to constrain the evolutionary models of low-mass pre-main-sequence stars by measuring resolved spectral energy distributions of stellar multiples in the visible band, more than doubling the current sample. I conclude this part with a discussion of possible future improvements to the Robo-AO system. In the second part, I describe a study of magnetar kinematics using high-resolution near-infrared (NIR) AO imaging from the 10-meter Keck II telescope. Measuring the proper motions of five magnetars with a precision of upto 0.7 milli-arcsecond/yr -1, we have more than tripled the previously known sample of magnetar proper motions and proved that magnetar kinematics are equivalent to those of radio pulsars. We conclusively showed that SGR 1900+14 and SGR 1806-20 were ejected from the stellar clusters with which they were traditionally associated. The inferred kinematic ages of these two magnetars are 6 +/- 1.8 kyr and 650 +/-3 00 yr respectively. These ages are a factor of three to four times greater than their respective characteristic ages. The calculated braking index is close to unity as compared to three for the vacuum dipole model and 2.5--2.8 as measured for young pulsars. I conclude this section by describing a search for NIR counterparts of new magnetars and a future promise of polarimetric investigation of a magnetars' NIR emission mechanism.

Tendulkar, Shriharsh Prakash

54

Performance of a MEMS-based AO-OCT system  

NASA Astrophysics Data System (ADS)

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution, 3-D images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging. The current system uses a bimorph deformable mirror (DM) made by AOptix Technologies, Inc. for low-order, high-stroke correction and a 140-actuator mirco-electrical-mechanical-system (MEMS) DM made by Boston Micromachines Corporation for high-order correction. We present our on-going characterization of AO system performance. The AO-OCT system typically has residual wavefront error of 100 nm rms. The correctable error in the system is dominated by low-order error that we believe is introduced by aliasing in the control loop. Careful characterization of the AO system will lead to improved performance and inform the design of future systems.

Evans, Julia W.; Zawadzki, Robert J.; Jones, Steve; Okpodu, Samelia; Olivier, Scot; Werner, John S.

2008-03-01

55

Constru»c~ao de codigos geometricamente uniformes utilizando tecnicas multin¶‡veis  

Microsoft Academic Search

Tecnicas convencionais de codiflca»c~ao de canal podem melhorar o desempenho de um sistema de comunica»c~ao sacriflcando a ocupa»c~ao de faixa es- pectral ou a taxa de transmiss~ao de informa»c~ao. Imai e Hirakawa sugeriram em (1) uma tecnica de codiflca»c~ao multin¶‡vel que utiliza varios codigos binarios de bloco para construir sistemas efl- cientes em largura de faixa. Recentemente, foi mostrado em

J. Portugheis; S. I. R. Costa; D. C. da Cunha; R. M. de Siqueira; J. Bali; B. S. Rajan; Block-coded PSK

56

ASSIST: the test setup for the VLT AO facility  

NASA Astrophysics Data System (ADS)

ASSIST: The Adaptive Secondary Setup and Instrument STimulator is the test setup for the verification and calibration of three elements of the VLT Adaptive Optics Facility.; the Deformable Secondary Mirror (DSM) the AO system for MUSE and HAWK-I (GALACSI and GRAAL). In the DSM testing mode the DSM will be tested using both interferometry and fast wave front sensing. In full AO mode, ASSIST will allow testing of the AO systems under realistic atmospheric conditions and optically equivalent to the conditions on the telescope. ASSIST is nearing its final design review and in this paper we present the current optical and mechanical design of ASSIST. In this paper we highlight some of the specific aspects of ASSIST that we are developing for ASSIST.

Stuik, Remko; Arsenault, Robin; Conzelmann, Ralf; Deep, Atul; Delabre, Bernard; Hallibert, Pascal; Jolissaint, Laurent; Hubin, Norbert; Kendrew, Sarah; Madec, Pierre-Yves; Molster, Frank; Paufique, Jerome; Pauwels, Evert; Stroebele, Stefan; Wiegers, Emiel

2008-07-01

57

High-Performance CCSDS AOS Protocol Implementation in FPGA  

NASA Technical Reports Server (NTRS)

The Consultative Committee for Space Data Systems (CCSDS) Advanced Orbiting Systems (AOS) space data link protocol provides a framing layer between channel coding such as LDPC (low-density parity-check) and higher-layer link multiplexing protocols such as CCSDS Encapsulation Service, which is described in the following article. Recent advancement in RF modem technology has allowed multi-megabit transmission over space links. With this increase in data rate, the CCSDS AOS protocol implementation needs to be optimized to both reduce energy consumption and operate at a high rate.

Clare, Loren P.; Torgerson, Jordan L.; Pang, Jackson

2010-01-01

58

Early experiences with the AO calcaneal fracture plate  

Microsoft Academic Search

We describe our early experiences using the new AO plate for open reduction and internal fixation of displaced intra-articular fractures of the calcaneum. An overview of our operative technique based on 22 cases is given. The relative merits of the new plate are discussed and we conclude that the plate is a useful device for dealing with this complex injury.

P. S. Kerr; M. Pape; M. Jackson; R. M. Atkins

1996-01-01

59

LGS-AO: the making of a star for astronomy.  

NASA Astrophysics Data System (ADS)

For astronomers, it all started in 1985 when Foy and Labeyrie (1985, A&A, 152, L29)published the concept of creating a laser guide star (LGS) in the mesospheric layer of the atmosphere to extend the use of adaptive optics (AO) to a much larger fraction of the astronomical sky. Shortly thereafter, the first sodium wavelength laser beam was propagated from Mauna Kea to validate the LGS concept (Thompson & Gardner 1987, Nature, 328, 229). In 1991, the results from the research undertaken by the U.S. Dept. of Defence were published in the open literature (Fugate et al. 1991, Nature, 353, 144). Experiments were subsequently performed at a number of Observatories (Apache Point, MMT, Calar Alto & Lick) resulting in one operational LGS-AO facility on the Lick 3-m telescope (Max et al. 1997, Science, 277, 1649). Today, Keck II LGS-AO, the first operational LGS-AO facility on an 8-10-m class telescope, is paving a new road for astronomical science by providing very high angular resolution (FWHMs of 50-60 mas with Strehls of 20-35% at K) over half of the sky. AO-corrected imagers and spectrographs at Keck and elsewhere will soon be used by a wider community of astronomers to complement and frequently surpass the observations obtained from space. We will present a review and a discussion of this powerful new instrumentation: the exciting scientific showcases and the challenges for combining complicated dynamic systems into productive, reliable and user-friendly instrumentation. We will provide an update on the forthcoming LGSAO intruments at other major observatories. We will report on the image quality performance, as well as on-sky observing efficiency, for the Keck II system (Wizinowich et al. 2005, PASP, submitted). As many astronomers plan for "AO all-the-time" on large and extremely large telescope, this talk will provide some information and lessons learned for how to best prepare for the bright LGS-AO future.

Le Mignant, D.

2005-12-01

60

Early Visible Adaptive Optics Science Results from MagAO's VisAO Camera in Simultaneous Differential Imaging (SDI) Mode: Disks and Point Sources  

NASA Astrophysics Data System (ADS)

We report on early science results from the newly-commissioned Magellan AO (MagAO) system's VisAO camera in Simultaneous Differential Imaging (SDI) mode. The MagAO Adaptive Secondary Mirror's high actuator pitch allow us to achieve AO correction into the visible wavelength regime, and VisAO is the first visible light science camera behind a large (d>6m) telescope AO system. This opens up an interesting new region of parameter space to high contrast, high spatial resolution science. As a natural guide star system, MagAO is optimized for circumstellar science, including both point source detection and high resolution imaging of circumstellar disks. Early SDI science results include the first circumstellar disk imaged in silhouette from the ground, high-resolution images of a binary propylid in Orion and high contrast images of an accreting point source at small separation.

Follette, Kate; Close, Laird; Wu, Ya-Lin; Males, Jared; Morzinski, Katie; Kopon, Derek

2013-07-01

61

Holocene Evolution of Qing'ao Embayment, Southern China  

NASA Astrophysics Data System (ADS)

The Holocene evolution of the Qing'ao embayment, Nan'ao Island, southern China, is primarily the result of the interaction of tectonic activity, climate variation and changes in relative sea level. Characterizing the evolutionary history of the relatively small Qing'ao embayment during the Holocene will help improve our understanding of the driving mechanisms of coastal evolution in the area. To reconstruct the Holocene evolution history we analyzed the grain size, loss on ignition (LOI) and carbonate content of modern and core samples. Modern environmental analogs were examined in surface samples ranging from the coastal sand dunes through to offshore. The results of these modern samples suggest that dune sand (mean size of ~2.33Phi) are slightly finer than beach sand (mean size of 2.13Phi), and nearshore sediment is much coarser than offshore sediment (mean size of 5.90Phi). This modern analogs were then applied to 8 percussion cores from the Qing'ao embayment. A chronological framework obtained from 11 radiocarbon samples suggests that the embayment started to accept deposition since early Holocene, ~8500 cal. yr. BP. Three main phases of Holocene evolution were identified. A basin wide shell-rich sand sheet forms the basal Holocene facies and overlies clay rich presumably Pleistocene sediments or bedrock. This facies records an initial sedimentation phase associated with the early Holocene transgression into the embayment (~8500-6000 cal. yr. BP). The basal facies grades upward to a mixed sandy-mud facies which includes lagoonal clayey-silts, flood tide delta sands and records an estuarine phase lasting from ~6000-1000 cal. yr. BP that appears coincident with falling regional sea levels. Coincident with the estuarine phase is a period of coastal dune building recorded as yet undated massive sands that are found in the upper fill. Toward the end of the estuarine phase it is apparent that dune migration has restricted the lagoon entrance and that this was contemporaneous with the final stages of infilling of the lagoon. The final phase of sedimentation is recorded as a thin terrestrial sequence dominated by fluvial floodplain facies that covers the last ~1000 cal. yr. BP and is topped by soils that also record enhanced anthropogenic modification over the last 1000 years. Our early results suggest that sea level and accomodation space are the main drivers for evolution of the Qing'ao embayment, as climate change during the Holocene in this region is relatively insignificant. However, as this area is reported to be tectonically active the impact of the tectonic movements on the evolution of Qing'ao embayment still requires further investigation.

Switzer, A. D.; Yu, F.; Chen, B.; Zheng, Z.; Wang, D.

2012-12-01

62

Speckle Imaging with VLT/NACO No-AO Mode  

NASA Astrophysics Data System (ADS)

Long-exposure stellar images recorded with large ground-based telescopes are blurred due to the turbulent nature of the atmosphere. The VLT employs active and adaptive optics (AO) systems to compensate for the deleterious effects of the atmosphere in real time. The speckle imaging technique provides an alternative way to achieve diffraction-limited imaging by post-processing a series of short-exposure images. The use of speckle imaging with the no-AO mode of NACO at the VLT is demonstrated. Application of this technique is particularly suited to the J-band and it provides versatile high angular resolution imaging under mediocre conditions and/or in imaging extended objects. The implementation of this mode underlines the continuing attractiveness of NACO at the VLT.

Rengaswamy, S.; Girard, J.; de Wit, W.-J.; Boffin, H.

2014-03-01

63

An advanced atmospheric dispersion corrector for extreme AO  

NASA Astrophysics Data System (ADS)

In addition to the BLINC/MIRAC IR science instruments, the Magellan adaptive secondary AO system will have an EEV CCD47 that can be used both for visible AO science and as a wide-field acquisition camera. The effects of atmospheric dispersion on the elongation of the diffraction limited Magellan adaptive optics system point spread function (PSF) are significant in the near IR. This elongation becomes particularly egregious at visible wavelengths, culminating in a PSF that is 2000?m long in one direction and diffraction limited (30-60 ?m) in the other over the wavelength band 0.5-1.0?m for a source at 45° zenith angle. The planned Magellan AO system consists of a deformable secondary mirror with 585 actuators. This number of actuators should be sufficient to nyquist sample the atmospheric turbulence and correct images to the diffraction limit at wavelengths as short as 0.7?m, with useful science being possible as low as 0.5?m. In order to achieve diffraction limited performance over this broad band, 2000?m of lateral color must be corrected to better than 10?m. The traditional atmospheric dispersion corrector (ADC) consists of two identical counter-rotating cemented doublet prisms that correct the primary chromatic aberration. We propose two new ADC designs: the first consisting of two identical counter-rotating prism triplets, and the second consisting of two pairs of cemented counter-rotating prism doublets that use both normal dispersion and anomalous dispersion glass in order to correct both primary and secondary chromatic aberration. The two designs perform 58% and 68%, respectively, better than the traditional two-doublet design. We also present our design for a custom removable wide-field lens that will allow our CCD47 to switch back and forth between an 8.6" FOV for AO science and a 25.8" FOV for acquisition.

Kopon, Derek; Close, Laird M.; Gasho, Victor

2008-07-01

64

On random walk de Lévy aplicado aos mapas de variâncias  

NASA Astrophysics Data System (ADS)

Uma pergunta que surge ao nos confrontarmos com os mapas de variâncias, ou s-Maps [Klafke, J. C. "Estudo da Difusão Caótica em Ressonâncias Asteroidais", Tese de Doutorado, IAG/USP, 2002] diz respeito ao conteúdo físico de tais representações do espaço de fase. Ou seja, o que representa as variâncias das ações obtidas para uma determinada condição inicial e como relacioná-las com o tempo de difusão das órbitas, supondo-se que estas de fato estejam envolvidas em um processo difusivo? Para discutirmos essa questão, lançamos mão da modelagem dos processos estocásticos subjacentes às variâncias determinadas e implementamos uma série de simulações do tipo Monte Carlo a partir das informações registradas nos s-Maps calculados para algumas ressonâncias asteroidais bem estudadas (p.ex. 3: 1, 2: 1 e 3: 2). Para tanto, temos usado uma função de densidade de probabilidade gaussiana ao definir os n passos que permitirão estabelecer uma relação direta entre o Mapa de Difusão e o Mapa de Variâncias. Contudo, os resultados obtidos até agora tem subestimado o tempo de difusão esperado para os fenômenos conhecidos. Tal se deve ao fato de que, no processo difusivo real, é possível existirem passos de comprimento consideravelmente maiores que a média estabelecida pelas distribuições gaussiana ou normal, sobretudo quando se cruza uma região caótica. Neste trabalho, apresentamos os resultados comparativos de simulações de Monte Carlo com base no random walk de Lévy [Klafter, J. et al. 2002. "Beyond Brownian motion", Phys. Today, Feb, 33-39.], o qual possibilita passos esporádicos de comprimento acima do valor médio (saltos) permitindo estabelecer uma escala de tempo mais próxima da esperada para a difusão.

Klafke, J. C.

2003-08-01

65

Simulations of (MC)AO for a 100-m telescope  

NASA Astrophysics Data System (ADS)

In this paper, we summarize the analysis made on various Adaptive Optics (AO) modes (including Shack-Hartmann (SH) and Pyramid Wavefront Sensors (PWS)) for the OverWhelmingly Large telescope (OWL). We will show some early results of the performance to be expected with a first generation AO system, working in the infrared. Several telescope diameters were considered to see the variations as a function of telescope diameter. This is also compatible with the concept of "grow a telescope" where the telescope diameter of OWL grows from 60m to 100m as a function of time. In a first phase, to simplify the problem, the effects of the central obstruction were neglected. However, for the Shack-Hartmann (SH) simulations, additional simulations were carried out with a simulated OWL pupil, including segmentation errors. We show some early results for a ground-layer correction system, working with three natural guide stars (NGSs) and a single deformable mirror (DM). An MCAO system based on 2 DMs, 3 NGSs is also investigated. For the last two systems, our results are found to be in very good agreement with Cibola, an analytical AO modeling tool. We show that some outer scale of turbulence effects improve slightly the correction quality when going from a telescope diameter of 10m to 100m.

Le Louarn, Miska; Verinaud, Christophe; Yaitskova, Natalia; Korkiakoski, Visa; Fedrigo, Enrico; Hubin, Norbert N.

2004-10-01

66

Laboratory demonstration of real time frame selection with Magellan AO  

NASA Astrophysics Data System (ADS)

The Magellan AO system combines a pyramid wavefront sensor and high-order adaptive secondary mirror, and will see first light on the Magellan Clay telescope in November 2012. With a 24 cm projected actuator pitch, this powerful system will enable good correction in the optical (0.5 to 1 ?m). Realistic laboratory testing has produced Strehl ratios greater than 40% in i’ (0.765 ?m) on bright simulated stars. On fainter stars our visible AO camera, VisAO, will work in the partially corrected regime with only short moments of good correction. We have developed a form of lucky imaging, called real time frame selection, which uses a fast shutter to block moments of bad correction, and quickly opens the shutter when the correction is good, enabling long integrations on a conventional CCD while maximizing Strehl ratio and resolution. The decision to open or shut is currently based on reconstructed WFS telemetry. Here we report on our implementation and testing of this technique in the Arcetri test tower in Florence, Italy, where we showed that long exposure i’ Strehl could be improved from 16% to 26% when the selection threshold was set to the best 10% of instantaneous Strehl.

Males, Jared R.; Close, Laird M.; Kopon, Derek; Quiros-Pacheco, Fernando; Riccardi, Armando; Xompero, Marco; Puglisi, Alfio; Gasho, Victor; Morzinski, Katie M.; Follette, Katherine B.

2012-07-01

67

Development and testing of an AO-structured illumination microscope  

NASA Astrophysics Data System (ADS)

The design of an Adaptive Optics (AO) Structured Illumination (SI) microscope is presented. Two key technologies are combined to provide effective super-resolution at significant depths in tissue. AO is used to measure and compensate for optical aberrations in both the system and the tissue by measuring the optical path differences in the wavefront. Uncorrected, these aberrations significantly reduce imaging resolution, particularly as we view deeper into tissue. SI allows us to reconstruct an image with resolution beyond the Rayleigh limit of the optics by aliasing high spatial frequencies, outside the limit of the optics, to lower frequencies within the system pass band. The aliasing is accomplished by spatially modulating the illumination at a frequency near the cutoff frequency of the system. These aliased frequencies are superimposed on the lower spatial frequencies of the object in our image. Using multiple images and an inverse algorithm, we separate the aliased and normal frequencies, restore them to their original frequency positions, and recreate the original spectrum of the object. This allows us to recreate a super-resolution image of the object. A problem arises with thick aberrating tissue. Tissue aberrations, including sphere, increase with depth into the tissue and reduce the high spatial frequency response of a system. This degrades the ability of SI to reconstruct at superresolution and limits its use to relatively shallow depths. However, adding AO to the system compensates for these aberrations allowing SI to work at maximum efficiency even deep within aberrating tissue.

Kissel, Matthew; Reinig, Marc; Azucena, Oscar; Díaz León, Juan J.; Kubby, Joel

2014-03-01

68

LDEF results for polymer matrix composite experiment AO 180  

NASA Technical Reports Server (NTRS)

This report represents a summary of the results obtained to-date on a polymer matrix composite experiment (AO 180) located at station D-12, about 82 deg off the 'ram' direction. Different material systems comprised of graphite, boron, and aramid (Kevlar) fiber reinforcements were studied. Although previous results were presented on in-situ thermal-vacuum cycling effects, particularly dimensional changes associated with outgassing, additional comparative data will be shown from ground-based tests on control and flight samples. The system employed was fully automated for thermal-vacuum cycling using a laser interferometer for monitoring displacements. Erosion of all three classes of materials due to atomic oxygen (AO) will also be discussed, including angle of incidence effects. Data from this experiment will be compared to published results for similar materials in other LDEF experiments. Composite materials' erosion yields will be presented on an AO design nomogram useful for estimating total material loss for given exposure conditions in low Earth orbit (LEO). Optical properties of these materials will also be compared with control samples. A survey of the damage caused by micrometeoroids/debris impacts will be addressed as they relate to polymer matrix composites. Correlations between hole size and damage pattern will be given. Reference to a new nomogram for estimating the number distribution of micrometeoroid/debris impacts for a given space structure as a function of time in LEO will be addressed based on LDEF data.

Tennyson, R. C.

1992-01-01

69

LDEF (Postflight), AO038 : Interstellar Gas Experiment, Tray H09  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO038 : Interstellar Gas Experiment, Tray H09 The postflight photograph was taken in the KSC SAEF II facility after the experiment was removed from the LDEF. The brown stains are still very prominent and appear to be the same as in the flight photograph. The openings in the base plate for the grid voltage cable connector mounts are thought to be the source of the darker brown stains around the connectors. The covers have been installed on the canister housings to protect the space exposed hardware. The contamination stain provides an out- line of tray clamp block locations on the experiment tray flanges.

1990-01-01

70

LDEF (Postflight), AO038 : Interstellar Gas Experiment, Tray H06  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO038 : Interstellar Gas Experiment, Tray H06 The postflight photograph was taken in the KSC SAEF II facility after the experiment was removed from the LDEF. The brown stains are still very prominent and appear to be the same as in the flight photograph. The openings in the base plate for the grid voltage cable connector mounts are thought to be the source of the darker brown stains around the connectors. The covers have been installed on the canister housings to protect the space exposed hardware. The contamination stain provides an out- line of tray clampblock locations on the experiment tray flanges.

1990-01-01

71

LDEF (Postflight), AO201 : Interplanetary Dust Experiment, Tray C03  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO201 : Interplanetary Dust Experiment, Tray C03 The IDE mounting plate and the detector frames are coated with a brown stain similiar to that seen on the other experiments in this and other trays located nearby. The stain seems to be slightly darker along the lower edge of the solar sensor mounting plate. The colors and designs seen on the detectors are reflections of the surrounding area. The thin brown film on the detectors metallic surface has resulted in a duller reflection of a technician, in the upper left, and other items.

1990-01-01

72

Aspect-Oriented Business Process Modeling with AO4BPMN  

NASA Astrophysics Data System (ADS)

Many crosscutting concerns in business processes need to be addressed already at the business process modeling level such as compliance, auditing, billing, and separation of duties. However, existing business process modeling languages including OMG's Business Process Modeling Notation (BPMN) lack appropriate means for expressing such concerns in a modular way. In this paper, we motivate the need for aspect-oriented concepts in business process modeling languages and propose an aspect-oriented extension to BPMN called AO4BPMN. We also present a graphical editor supporting that extension.

Charfi, Anis; Müller, Heiko; Mezini, Mira

73

Study on correcting angle-of-arrival fluctuations of space optical communication with AO  

NASA Astrophysics Data System (ADS)

The method of correcting angle-of-arrival fluctuations with adaptive optics (AO) is presented in this article. Numerical simulation is used for analyzing and studying the effect of AO correction and its influence factors. The simulative results indicate that AO can correct angle-of-arrival fluctuations induced by atmosphere turbulence effectively and the effect of AO correction is related with wavelength and aperture.

Li, Fang; Rong, Jian; Zhong, Xiao-chun; Ding, Xue-ke

2007-11-01

74

New Results from the AO327 Drift Pulsar Survey  

NASA Astrophysics Data System (ADS)

The Arecibo 327 MHz drift pulsar survey (AO327) has operated since 2010 and aims to cover the entire Arecibo sky (declinations of -1 to 38 degrees). We present details on the progress of the survey and a new set of discoveries over the past year. Phase 1 of AO327 targets declinations of -1 to 28 degrees and is 55% complete; Phase 2 will target declinations of 28 to 38 degrees. The survey is expected to be completed in 2017. Out of a total of 28 new pulsars, 12 were found in 2013, including three millisecond pulsars. PSR J2234+06 has a rotation period of 3.58 ms and is in a 32-day orbit in a binary system with a white dwarf companion. This pulsar is bright and a very stable rotator, making it suitable for inclusion in Pulsar Timing Arrays. The orbit of J2234+06 has an eccentricity of 0.13, which cannot be accounted for by stellar evolution but may be explained by an origin in a subsequently disrupted hierarchical triple, or by an exchange interaction. PSR J0509+08 has a period of 4.06 ms and is in a 4.9-day binary system with a white dwarf companion. This pulsar is also a candidate for inclusion in PTAs.

Deneva, Julia S.; Stovall, K.; McLaughlin, M.; Bates, S.; Freire, P.; Martinez, J.; Jenet, F.; Bagchi, M.

2014-01-01

75

Searching and Studying Binary Asteroids with AO Systems  

NASA Astrophysics Data System (ADS)

Our group has conducted adaptive optics observations of asteroids since 2001. Our main goal is the search and study of binary asteroids using several AO systems (Lick, Keck, VLT) and related technique such as Appulse (Berthier and Marchis, 2002) and Laser Guide Star observations (Marchis et al., AGU-EGS, 2003) to broaden the sample of asteroids observed from the main-belt out to the Kuiper Belt. We focussed our program last year on Trojan Asteroids. Six of them were observed using Appulses with Keck AO ( ˜0.05-0.10", mv=15.4-18.5), 6 with the LGS at Lick ( ˜0.25-0.35", mv<16) and 12 with the VLT/NACO system ( ˜0.10-0.14"; mv<16.7). None of these observations reveals the presence of a companion. Based on this sample, and including 617 Patroclus binary asteroid discovered by Merline et al. (IAU, 7741, 2001), we deduce that the proportion of binary Trojan asteroids larger than 40 km is less than 4%. We will promote and discuss a technique of the analysis of negative discovery in large samples. In January 2003, we conducted an observing campaign spanning 5 days of 121 Hermione with NACO, the new AO system offered at VLT. This C-type asteroid was discovered by Merline et al. (IAU, 7980, 2002). The companion, 6.1 mag fainter than the primary, is easily detected despite the faintness of the asteroid (mv ˜13). We use the method described in Marchis et al. (Icarus, 2003) to determine the orbit of the companion. Its orbital elements are a=794.7+/-2.1 km, and P=1.643+/-0.005 days. We derived a mass =1.47E19 kg, and a density of 3.1+/-0.8 g cm-3 (using IRAS diameter of 209+/-4.7 km). Considering typical densities of meteorite analogues (CI or CM carboneceous chondrite) would led to an extremely low macro-porosity of p<3%. This suggests that the volume of Hermione is ˜30% larger, which is also supported by our resolved images of this body. This work supported by the National Science Foundation Science and Technology Center for Adaptive Optics, based partly on observations collected at the European Southern Observatory, Chile.

Marchis, F.; Descamps, P.; Berthier, J.; Hestroffer, D.; de Pater, I.; Conrad, A.; Le Mignant, D.; Chaffee, F.; Gavel, D.

2003-05-01

76

High Contrast Imaging of an Exoplanet with the Magellan VisAO Camera  

NASA Astrophysics Data System (ADS)

The Magellan Adaptive Optics (MagAO) system saw first light in November 2012 at Las Campanas Observatory (LCO) on the 6.5m Clay telescope. Here we present an introduction to MagAO's visible wavelength diffraction limited imager, VisAO. VisAO delivers Strehl ratios greater than 30% from 0.62 microns (r') through 1 micron, where Strehl is even higher, and achieved resolutions as small as 20 milli-arcseconds. We took advantage of the excellent performance of MagAO/VisAO to conduct high contrast observations of an exoplanet in the optical. With VisAO, we are, for the first time, able to begin characterizing exoplanet atmospheres in the optical from the ground.

Males, Jared R.; Close, Laird M.; Morzinski, Katie M.; Kopon, Derek; Puglisi, Alfio; Gasho, Victor; Follette, Kate; Esposito, Simone; Riccardi, Armando; Pinna, Enrico; Xompero, Marco; Briguglio, Runa; Arcidiacono, Carmelo; Hinz, Phil M.; Uomoto, Alan; Hare, Tyson; Quiros-Pacheco, Fernando; Argomedo, Javier; Busoni, Lorenzo; Rodigas, T. J.; Wu, Ya-Lin

2014-01-01

77

LDEF (Postflight), AO201 : Interplanetary Dust Experiment, Tray H11  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO201 : Interplanetary Dust Experiment, Tray H11 The Interplanetary Dust Experiment hardware has a thin brown stain on the exposed surfaces. A deeper brown stain, probably from the material underneath the small electrical cover plate of the detector frame, can be seen in the upper right corner of some of the detectors. Stain that was seen on the solar sensor base plate in the flight photograph cannot be seen because of reflected light. The colors seen in the detector's mirror like surface are reflections of the surrounding area. A dark spot seen on a detector in the third row from the top in the flight photograph, was not found in a postflight inspection. A close inspection of this photograph does reveal several impact damage locations.

1990-01-01

78

Progress report of USAF Research Laboratory liquid crystal AO program  

NASA Astrophysics Data System (ADS)

In this paper we present a status report of our liquid crystal (LC) adaptive optics program. Liquid crystal have been proposed to be used for adaptive optics components by several authors. We are actively pursuing a two prong approach, on one side we have built a closed loop test bed based on a 127 element nematic LC device; on the other side we are actively involved in research on the ferroelectric side of the LC devices. In this paper we present preliminary results from our testbed. The essential elements of this testbed are a Shack-Hartman based wavefront sensors with an analog reconstructor, and the 127 nematic elements from Meadowlark Optics. Some of the basic experimental parameters will be reviewed, and result will be discussed. Furthermore we will present the status of our activity in the field of ferroelectric LC. Several prototypes are under testing to establish their capabilities as AO components.

Restaino, Sergio R.; Payne, Don; Anderson, Michael H.; Baker, Jeffrey T.; Serati, Steven A.; Loos, Gary C.

1998-09-01

79

The nature of the BL Lacertae object AO 0235 + 164  

NASA Technical Reports Server (NTRS)

Emission features in the optical spectrum of the highly variable BL Lac object AO 0235 + 164 have been detected which are identified as Mg II, forbidden Ne V, and forbidden O II at a redshift of 0.9399, consistent with a cosmological interpretation of the two absorption systems at z = 0.524 and z = 0.851. The spectrum also shows emission features associated with the z = 0.524 system at a projected separation of 20 kpc from the apparent central concentration of the material producing that absorption. This implies a highly extended and very luminous line-emitting region for the material at z = 0.524. A comparison of the new data with previous spectroscopic observations of the BL Lac object when it was faint suggests that the Mg II emission may be variable on a time scale of approximately 2 yr.

Cohen, Ross D.; Smith, Harding E.; Junkkarinen, Vesa T.; Burbidge, E. Margaret

1987-01-01

80

LDEF (Postflight), AO201 : Interplanetary Dust Experiment, Tray G10  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO201 : Interplanetary Dust Experiment, Tray G10 The IDE experiment appears to be in excellent condition in the postflight photograph. All bond joints seem to have survived the space environment and the experiment hardware seems to be intact. The direction and intensity of the artificial light source has caused hot spots and reflections that tend to wash out the brown stain on the exposed surfaces. A close inspection of individual detectors reveal locations where impacts have occurred and damage is present. In the detector layout in the lower left corner of the tray, two detectors continue to show the discolorations observed in the flight photograph. A triangular shape can be seen in the detector located in the second horizontal row from the bottom and the second vertical row from the left. The other detector, located in the third horizontal row from the bottom and the fourth vertical row from the left has an irregular shaped, very faint, discolora tion. The blue color in the detectors metallic surface is caused by reflections of the surrounding area.

1990-01-01

81

Shape and Size of Asteroid (41) Daphne from AO Imaging  

NASA Astrophysics Data System (ADS)

As part of our ongoing programs to use adaptive optics (AO) to study asteroids for size, shape, and presence of satellites, we observed asteroid (41) Daphne during its recent close (1.05 AU) opposition. In March 2008, we discovered a small satellite to Daphne at Keck (Conrad et al. 2008, IAUC 8939; Merline et al. 2008, ACM 2008, #8370). Follow up observations at Keck and VLT allowed us to refine the orbit. The unusually short period of the satellite ( 1.1 day) and the estimated size (239x183x153 km) from our observations lead to a density near 2.0 g/cc. This is significantly higher than most other large C-types with densities determined from presence of a moon (Merline et al. 2002, Asteroids III, 289). Because of this surprising density, and because we expect to derive an exceptionally accurate volume from our data, we are placing special emphasis on our size and shape determinations. One of the peculiarities is that this object is highly irregular in shape. We demonstrate several methods of determining the volume, including triaxial ellipsoid fits, detailed shape modeling, and improving estimates by using existing lightcurve information (e.g., from Kaasalainen et al.).

Conrad, Al; Carry, B.; Drummond, J. D.; Merline, W. J.; Dumas, C.; Owen, W. M.; Chapman, C. R.; Tamblyn, P. M.; Goodrich, R. W.; Campbell, R. D.

2008-09-01

82

Ruled and holographic experiment (AO 138-5)  

NASA Technical Reports Server (NTRS)

The AO 138-5 experiment was designed, via the FRECOPA (FRench COoperative PAyload) experiment with the aim to study the optical behavior of different diffraction gratings submitted to space vacuum long exposure and solar irradiation. Samples were ruled and holographic gratings, masters or replica, and some additional control mirrors with various coatings. The experiment was located on the B3, trailing edge of the LDEF and was protected against Atomic Oxygen flux. The experienced thermal cycling was evaluated from -23 C to 66 C during the flight, 34,000 orbits. The samples (two batches of four pieces) were located on a dedicated plate, by a pair of equivalent gratings or mirrors; optical faces were located on the external side. The plate was inside a canister, which had been opened in space for ten months. When the satellite returned to Kennedy Space Center, the remaining vacuum in the canister was still correct. The analysis focused on the triple point characterization including light efficiency, wavefront flatness quality and stray light level. Tests were conducted on control mirrors and gratings (rules and holographic master or replica) loaded but not exposed to cosmic dust or direct solar irradiations. They did not show any significant variations. Solar exposure had damaged the coating (aluminum and platinum) reflectivity in the Ultra-Violet region; the degradation is higher with the gratings, in terms of efficiency. However, wavefront flatness quality and stray light level tests revealed no additional changes.

Bonnemason, Francis

1993-01-01

83

Near-infrared AO imaging of QSO host galaxies  

NASA Astrophysics Data System (ADS)

We report NIR (primarily H-band) AO imaging with the Gemini-N and Subaru telescopes, of 32 nearby ( z < 0.3) QSOs selected from the Palomar-Green bright quasar survey (PGBQS), in order to investigate the properties of the host galaxies. Two-dimensional modeling and visual inspection of the images shows that ˜36% of the hosts are ellipticals, ˜39% contain a prominent disk component, and ˜25% are of undetermined type. Thirty percent show obvious signs of disturbance. The mean MH(host) = -24.82 ( 2.1LH*), with a range -23.5 to -26.5. At 2LH* most are ellipticals. "Disturbed" hosts are found at all MH(host). Hosts with prominent disks have less luminous QSOs, while the most luminous QSOs are almost exclusively in ellipticals or in mergers (which presumably shortly will be ellipticals). There is a strong correlation between the "infrared-excess", LIR/ LBB, of QSOs with host type and degree of disturbance. Disturbed and strongly disturbed hosts and hosts with dominant disks have LIR/ LBB twice that of non-disturbed and elliptical hosts, respectively.

Guyon, O.; Sanders, D. B.; Stockton, A. N.

2006-11-01

84

MCP-Medipix2 hybrid detector for AO wavefront sensors  

NASA Astrophysics Data System (ADS)

A hybrid optical detector being developed at Berkeley has most of the attributes desired for the next generation AO wavefront sensors. The detector consists of proximity focused MCPs read out by a multi-pixel application specific integrated circuit (ASIC) chip developed at CERN ("Medipix2") with individual pixels that amplify, discriminate and count input events. The detector has 256 x 256 pixels, zero readout noise (photon counting) and can be read out at 1kHz frame rates. We will report on the progress achieved after two years of our three year development effort for this detector technology funded as part of the Adaptive Optics Development Program managed by the National Optical Astronomy Observatory. Details on the first vacuum tube constructed with a Medipix2 ASIC along with the fast kHz parallel electronic readout are presented. We also describe a new hybrid detector design based on HgCdTe APD arrays coupled to a Medipix2 readout that could bring zero readout noise at high frame rates to the near IR regime.

Vallerga, John; McPhate, Jason; Mikulec, Bettina; Clark, Allan; Siegmund, Oswald

2006-07-01

85

Atomic oxygen effects on LDEF experiment AO171  

NASA Astrophysics Data System (ADS)

The Solar Array Materials Passive Long Duration Exposure Facility (LDEF) Experiment (SAMPLE), AO171, contained in total approximately 100 materials and materials processes with a 300 specimen complement. With the exception of experiment solar cell and solar cell modules, all test specimens were weighed before flight, thus allowing an accurate determination of mass loss as a result of space exposure. Since almost all of the test specimens were thermal vacuum baked before flight, the mass loss sustained can be attributed principally to atomic oxygen attack. The atomic oxygen effects observed and measured in five classes of materials is documented. The atomic oxygen reactivity values generated for these materials are compared to those values derived for the same materials from exposures on short term shuttle flights. An assessment of the utility of predicting long term atomic oxygen effects from short term exposures is given. This experiment was located on Row 8 position A which allowed all experiment materials to be exposed to an atomic oxygen fluence of 6.93 x 10(exp 21) atoms/cm(sup 2) as a result of being positioned 38 degrees off the RAM direction.

Whitaker, Ann F.; Kamenetzky, Rachel R.; Finckenor, Miria M.; Norwood, Joseph K.

1993-04-01

86

Modelo An\\\\'alogo Ac\\\\'ustico ao Buraco Negro de Schwarzschild  

Microsoft Academic Search

Um fluido em movimento pode agir sobre o som da mesma forma que os espa\\\\c{c}o-tempos curvos podem influenciar na trajet\\\\'oria da luz na relatividade geral. Com isso, pode-se descrever a propaga\\\\c{c}\\\\~ao dessas ondas sonoras atrav\\\\'es de uma m\\\\'etrica efetiva, sob a qual elas seguir\\\\~ao geod\\\\'esicas nulas. Esta disserta\\\\c{c}\\\\~ao faz uma revis\\\\~ao destes estudos concentrando-se em uma analogia ac\\\\'ustica para um

Júnior Diniz Toniato

2011-01-01

87

Diferentes metodologias aplicadas ao ensino de astronomia no Ensino Médio  

NASA Astrophysics Data System (ADS)

O presente trabalho de intervenção foi realizado junto à Escola Estadual Colònia dos Pescadores na cidade de Caraguatatuba, com très turmas do terceiro ano do Ensino Médio, envolvendo 119 alunos com idades entre 16 e 19 anos. A fase inicial foi composta de um questionário de vinte questíes dissertativas e objetivas, aplicado pelo professor titular da sala, que era o mesmo nas très turmas, para diagnosticar nos educandos os conceitos prévios sobre Astronomia e, partindo destes realizar um trabalho de intervenção nas classes envolvidas utilizando, em cada uma, metodologias diferentes: (A) sob forma de seminários, elaborados e apresentados pelos educandos, no qual o educador faz apenas as intervençíes necessárias; (B) de forma tradicional, com auxílio de multimídias para desenvolvimento das aulas e a terceira (C) tradicional, fazendo uso exclusivo de lousa e giz. Ao final do trabalho os alunos responderam novamente o questionário inicial para diagnosticar dentre as très metodologias utilizadas qual apresentou melhores aplicaçíes, os resultados iniciais foram comparados com os finais. Quando questionados a respeito do significado de Astronomia observou-se inicialmente que os acertos na turma A foram de 100%, turma B: 64%, turma C: 84%, após a intervenção os acertos foram: 100%, 97% e 85% respectivamente, demonstrando que houve um avanço significativo na turma B, a turma A manteve seu índice e a turma C evoluiu, porém não tanto quanto a B. Quando interrogados sobre quantos planetas vocè acha que existem em nosso Sistema Solar? os acertos foram: turma A: 39%, turma B: 48% e turma C: 46%, após o desenvolvimento do trabalho os acertos foram 94%, 97% e 90% respectivamente. Dentro das respostas obtidas observa-se que a metodologia tradicional com o auxílio de multimeios, aplicada na turma B, demonstrou melhores resultados, sendo a mais significativa. Outra conclusão muito importante é que apesar de o tema Astronomia ser amplamente recomendado, este não é ensinado, nem no Ensino Fundamental, nem no Ensino Médio.

Albrecht, E.; Voelzke, M. R.

2009-03-01

88

AO Capabilities at the MMT for the User  

NASA Astrophysics Data System (ADS)

The MMT operates a facility natural guide star (NGS) AO system. Diffraction limited imaging and medium and high resolution spectroscopy in the near IR are offered over the full isoplanatic field with the ARIES instrument.The system also offers imaging with unique sensitivity in the thermal IR from 3 to 10 microns thanks to its use of an adaptive secondary mirror. L and M band imaging is offered with Clio which has a 12x15 arcsec field of view with Nyquist sampling if the diffraction limt. Recent M band images from Clio show the planetary system around HR8799. In addition, 10 - 25 micron imaging is offered with the MIRAC camera, which may also be operated as a Bracewell nulling interferometer. In this mode, two large subapertures are defined within the pupil. Light from the two is combined so as to cancel the light from an unresolved star through destructive interference, while the environs are imaged in constructive interference. In this way, dust disks and planetary systems may be imaged with greatly improved contrast. The MMT also operates the first astronomical adaptive optics system to employ multiple laser guide stars (LGS). Its initial operational mode, ground-layer adaptive optics (GLAO), provides uniform stellar wavefront correction within the 2 arcmin diameter laser beacon constellation, routinely reducing the stellar image widths to < 0.3 arcsec in the J - K bands. An imaging camera,PISCES, is available for these bands with 2 arcmin field of view sampled at 0.1 arcsec/pixel. In addition, L and M band imaging will be available with Clio in the fall of 2009, opening up near all-sky coverage with near-diffraction limited image quality and emissivity of just 7%.

Lloyd-Hart, Michael M.

2009-05-01

89

Patterns of Impairments in AOS and Mechanisms of Interaction between Phonological and Phonetic Encoding  

ERIC Educational Resources Information Center

Purpose: One reason why the diagnosis of apraxia of speech (AOS) and its underlying impairment are often debated may lie in the fact that most patients do not display pure patterns of AOS. Mixed patterns are clearly acknowledged at other levels of impairment (e.g., lexical-semantic and lexical-phonological), and they have contributed to debate…

Laganaro, Marina

2012-01-01

90

Enabling Technologies for Visible Adaptive Optics: The Magellan Adaptive Secondary VisAO Camera  

Microsoft Academic Search

Since its beginnings, diffraction-limited ground-based adaptive optics (AO) imaging has been limited to wavelengths in the near IR ({\\\\lambda} > 1 micron) and longer. Visible AO ({\\\\lambda} < 1 micron) has proven to be difficult because shorter wavelengths require wavefront correction on very short spatial and temporal scales. The pupil must be sampled very finely, which requires dense actuator spacing

Derek Kopon; Jared R. Males; Laird M. Close; Victor Gasho

2010-01-01

91

LDEF: Dosimetric measurement results (AO 138-7 experiment)  

NASA Technical Reports Server (NTRS)

One of the objectives of the AO 138-7 experiment on board the Long Duration Exposure Facility (LDEF) was a total dose measurement with Thermo Luminescent Detectors (TLD 100). Two identical packages, both of them including five TLD's inside various aluminum shields, are exposed to the space environment in order to obtain the absorbed dose profile. Radiation fluence received during the total mission length was computed, taking into account the trapped particles (AE8 and AP8 models during solar maximum and minimum periods) and the cosmic rays; due to the magnetospheric shielding the solar proton fluences are negligible on the LDEF orbit. The total dose induced by these radiations inside a semi infinite plane shield of aluminum are computed with the radiation transport codes available at DERTS. The dose profile obtained is in good agreement with the evaluation by E.V. Benton. TLD readings are performed after flight; due to the mission duration increase a post flight calibration was necessary in order to cover the range of the in flight induced dose. The results obtained, similar (plus or minus 30 percent) for both packages, are compared with the dose profile computation. For thick shields it seems that the measurements exceed the forecast (about 40 percent). That can be due to a cosmic ray and trapped proton contributions coming from the backside (assumed as perfectly shielded by the LDEF structure in the computation), or to an underestimate of the proton or cosmic ray fluences. A fine structural shielding analysis should be necessary in order to determine the origin of this slight discrepancy between forecast and in flight measurements. For the less shielded dosimeters, mainly exposed to the trapped electron flux, a slight overestimation of the dose (less than 40 percent) appears. Due to the dispersion of the TLD's response, this cannot be confirmed. In practice these results obtained on board LDEF, with less than a factor 1.4 between measurements and forecast, reinforce the validity of the computation methods and models used for the long term evaluation of the radiation levels (flux and dose) encountered in space on low inclination and altitude Earth orbits.

Bourrieau, J.

1993-01-01

92

Bringing the visible universe into focus with Robo-AO.  

PubMed

The angular resolution of ground-based optical telescopes is limited by the degrading effects of the turbulent atmosphere. In the absence of an atmosphere, the angular resolution of a typical telescope is limited only by diffraction, i.e., the wavelength of interest, ?, divided by the size of its primary mirror's aperture, D. For example, the Hubble Space Telescope (HST), with a 2.4-m primary mirror, has an angular resolution at visible wavelengths of ~0.04 arc seconds. The atmosphere is composed of air at slightly different temperatures, and therefore different indices of refraction, constantly mixing. Light waves are bent as they pass through the inhomogeneous atmosphere. When a telescope on the ground focuses these light waves, instantaneous images appear fragmented, changing as a function of time. As a result, long-exposure images acquired using ground-based telescopes--even telescopes with four times the diameter of HST--appear blurry and have an angular resolution of roughly 0.5 to 1.5 arc seconds at best. Astronomical adaptive-optics systems compensate for the effects of atmospheric turbulence. First, the shape of the incoming non-planar wave is determined using measurements of a nearby bright star by a wavefront sensor. Next, an element in the optical system, such as a deformable mirror, is commanded to correct the shape of the incoming light wave. Additional corrections are made at a rate sufficient to keep up with the dynamically changing atmosphere through which the telescope looks, ultimately producing diffraction-limited images. The fidelity of the wavefront sensor measurement is based upon how well the incoming light is spatially and temporally sampled. Finer sampling requires brighter reference objects. While the brightest stars can serve as reference objects for imaging targets from several to tens of arc seconds away in the best conditions, most interesting astronomical targets do not have sufficiently bright stars nearby. One solution is to focus a high-power laser beam in the direction of the astronomical target to create an artificial reference of known shape, also known as a 'laser guide star'. The Robo-AO laser adaptive optics system, employs a 10-W ultraviolet laser focused at a distance of 10 km to generate a laser guide star. Wavefront sensor measurements of the laser guide star drive the adaptive optics correction resulting in diffraction-limited images that have an angular resolution of ~0.1 arc seconds on a 1.5-m telescope. PMID:23426078

Baranec, Christoph; Riddle, Reed; Law, Nicholas M; Ramaprakash, A N; Tendulkar, Shriharsh P; Bui, Khanh; Burse, Mahesh P; Chordia, Pravin; Das, Hillol K; Davis, Jack T C; Dekany, Richard G; Kasliwal, Mansi M; Kulkarni, Shrinivas R; Morton, Timothy D; Ofek, Eran O; Punnadi, Sujit

2013-01-01

93

Bringing the Visible Universe into Focus with Robo-AO  

PubMed Central

The angular resolution of ground-based optical telescopes is limited by the degrading effects of the turbulent atmosphere. In the absence of an atmosphere, the angular resolution of a typical telescope is limited only by diffraction, i.e., the wavelength of interest, ?, divided by the size of its primary mirror's aperture, D. For example, the Hubble Space Telescope (HST), with a 2.4-m primary mirror, has an angular resolution at visible wavelengths of ~0.04 arc seconds. The atmosphere is composed of air at slightly different temperatures, and therefore different indices of refraction, constantly mixing. Light waves are bent as they pass through the inhomogeneous atmosphere. When a telescope on the ground focuses these light waves, instantaneous images appear fragmented, changing as a function of time. As a result, long-exposure images acquired using ground-based telescopes - even telescopes with four times the diameter of HST - appear blurry and have an angular resolution of roughly 0.5 to 1.5 arc seconds at best. Astronomical adaptive-optics systems compensate for the effects of atmospheric turbulence. First, the shape of the incoming non-planar wave is determined using measurements of a nearby bright star by a wavefront sensor. Next, an element in the optical system, such as a deformable mirror, is commanded to correct the shape of the incoming light wave. Additional corrections are made at a rate sufficient to keep up with the dynamically changing atmosphere through which the telescope looks, ultimately producing diffraction-limited images. The fidelity of the wavefront sensor measurement is based upon how well the incoming light is spatially and temporally sampled1. Finer sampling requires brighter reference objects. While the brightest stars can serve as reference objects for imaging targets from several to tens of arc seconds away in the best conditions, most interesting astronomical targets do not have sufficiently bright stars nearby. One solution is to focus a high-power laser beam in the direction of the astronomical target to create an artificial reference of known shape, also known as a 'laser guide star'. The Robo-AO laser adaptive optics system2,3 employs a 10-W ultraviolet laser focused at a distance of 10 km to generate a laser guide star. Wavefront sensor measurements of the laser guide star drive the adaptive optics correction resulting in diffraction-limited images that have an angular resolution of ~0.1 arc seconds on a 1.5-m telescope.

Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Ramaprakash, A.N.; Tendulkar, Shriharsh P.; Bui, Khanh; Burse, Mahesh P.; Chordia, Pravin; Das, Hillol K.; Davis, Jack T.C.; Dekany, Richard G.; Kasliwal, Mansi M.; Kulkarni, Shrinivas R.; Morton, Timothy D.; Ofek, Eran O.; Punnadi, Sujit

2013-01-01

94

Bringing the Visible Universe into Focus with Robo-AO  

NASA Astrophysics Data System (ADS)

The angular resolution of ground-based optical telescopes is limited by the degrading effects of the turbulent atmosphere. In the absence of an atmosphere, the angular resolution of a typical telescope is limited only by diffraction, i.e., the wavelength of interest, ?, divided by the size of its primary mirror's aperture, D. For example, the Hubble Space Telescope (HST), with a 2.4-m primary mirror, has an angular resolution at visible wavelengths of ~0.04 arc seconds. The atmosphere is composed of air at slightly different temperatures, and therefore different indices of refraction, constantly mixing. Light waves are bent as they pass through the inhomogeneous atmosphere. When a telescope on the ground focuses these light waves, instantaneous images appear fragmented, changing as a function of time. As a result, long-exposure images acquired using ground-based telescopes - even telescopes with four times the diameter of HST - appear blurry and have an angular resolution of roughly 0.5 to 1.5 arc seconds at best. Astronomical adaptive-optics systems compensate for the effects of atmospheric turbulence. First, the shape of the incoming non-planar wave is determined using measurements of a nearby bright star by a wavefront sensor. Next, an element in the optical system, such as a deformable mirror, is commanded to correct the shape of the incoming light wave. Additional corrections are made at a rate sufficient to keep up with the dynamically changing atmosphere through which the telescope looks, ultimately producing diffraction-limited images. The fidelity of the wavefront sensor measurement is based upon how well the incoming light is spatially and temporally sampled. Finer sampling requires brighter reference objects. While the brightest stars can serve as reference objects for imaging targets from several to tens of arc seconds away in the best conditions, most interesting astronomical targets do not have sufficiently bright stars nearby. One solution is to focus a high-power laser beam in the direction of the astronomical target to create an artificial reference of known shape, also known as a 'laser guide star'. The Robo-AO laser adaptive optics system employs a 10-W ultraviolet laser focused at a distance of 10 km to generate a laser guide star. Wavefront sensor measurements of the laser guide star drive the adaptive optics correction resulting in diffraction-limited images that have an angular resolution of ~0.1 arc seconds on a 1.5-m telescope.

Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Ramaprakash, A. N.; Tendulkar, Shriharsh P.; Bui, Khanh; Burse, Mahesh P.; Chordia, Pravin; Das, Hillol K.; Davis, Jack T. C.; Dekany, Richard G.; Kasliwal, Mansi M.; Kulkarni, Shrinivas R.; Morton, Timothy D.; Ofek, Eran O.; Punnadi, Sujit

2013-02-01

95

LDEF (Prelaunch), AO201 : Interplanetary Dust Experiment, Tray B12  

NASA Technical Reports Server (NTRS)

LDEF (Prelaunch), AO201 : Interplanetary Dust Experiment, Tray B12 The prelaunch photograph shows the six (6) inch deep Interplanetary Dust Experiment (IDE) master control tray. The tray has three (3) mounting/cover plates elevated on fiberglass stand-offs to provide clearance and protection for hardware and electronics located underneath. The stand-offs also raise the plates to a level that minimizes shading of detectors by the tray sidewalls. The mounting plate located at the left hand end of the tray is populated with eighty (80) metaloxide-silicon (MOS) capacitor-type impact sensors and one (1) solar sensor that is located approximately in the center of the mounting plate. The IDE sensors are two (2) inch diameter MOS capacitor structures approximately 250 um thick. The detectors are formed by growing either 0.4um or 1.0um thick silicon oxide, SiO2, layer on the 250um thick, B-doped polished silicon wafer. The top metal contact, the visible surface, was formed by vapor deposition of 1000A of aluminum on the SiO2 surface. Aluminum was also vapor deposited on the backside to form the contact with the silicon substrate. Gold wires are bonded to the front and back aluminum layers for use in connecting the detectors to the circuits. The complete wafers, IDE detectors, are mounted on chromic anodized aluminum frames by bonding the detector backside to the aluminum frame with a space qualified RTV silicon adhesive, de-volatized RTV-511. The difference in colors of the detectors is caused by reflections in the metallized surfaces. A reflection of one of the technicians is visible in the three (3) rows of detector on the left hand side of the mounting plate. The solar sensor, located at the mounting plate center, consist of four (4) silicon solar cells connected in series and associated circuity bonded to an aluminum baseplate. The solar sensor registered each orbital sunrise independant of LDEF orientation at the time of sunrise. When IDE solar sensor data from the six (6) orthogonal faces of the LDEF was correlated, the Interplanetary Dust Experiment clock could be precisely calibrated. The center 1/3rd tray cover is a chromic anodized aluminum plate that protects the IDE data conditioning and control electronics mounted underneath. The cover plate also serves as a mounting platform for ten (10) individual specimen holders provided by one of the IDE investigators.The material specimen, consisting of germanium, sapphire and zinc sulfide of different sizes, shapes and colors, are bonded to the specimen holders with an RTV adhesive. The specimen holders are attached to the cover plate with stainless steel non-magnetic fasteners. The 1/3rd tray cover plate in the right hand end of the experiment tray is an aluminum plate painted white with Chemglaze II A-276 paint and used as a thermal cover for the Experiment Power and Data System (EPDS). The EPDS is a system provided by the LDEF Project Office that processes and stores, on magnetic tape, the orbital experiment and housekeeping data from six (6) experiment locations on the LDEF.

1984-01-01

96

CLASSICAL AREAS OF PHENOMENOLOGY: Correcting dynamic residual aberrations of conformal optical systems using AO technology  

NASA Astrophysics Data System (ADS)

This paper analyses the dynamic residual aberrations of a conformal optical system and introduces adaptive optics (AO) correction technology to this system. The image sharpening AO system is chosen as the correction scheme. Communication between MATLAB and Code V is established via ActiveX technique in computer simulation. The SPGD algorithm is operated at seven zoom positions to calculate the optimized surface shape of the deformable mirror. After comparison of performance of the corrected system with the baseline system, AO technology is proved to be a good way of correcting the dynamic residual aberration in conformal optical design.

Li, Yan; Li, Lin; Huang, Yi-Fan; Du, Bao-Lin

2009-07-01

97

On-Sky Speckle Nulling Demonstration at Small Angular Separation with SCExAO  

NASA Astrophysics Data System (ADS)

This paper presents the first on-sky demonstration of speckle nulling, which was achieved at the Subaru Telescope in the context of the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) Project. Despite the absence of a high-order high-bandwidth closed-loop AO system, observations conducted with SCExAO show that even in poor-to-moderate observing conditions, speckle nulling can be used to suppress static and slow speckles even in the presence of a brighter dynamic speckle halo, suggesting that more advanced high-contrast imaging algorithms developed in the laboratory can be applied to ground-based systems.

Martinache, Frantz; Guyon, Olivier; Jovanovic, Nemanja; Clergeon, Christophe; Singh, Garima; Kudo, Tomoyuki; Currie, Thayne; Thalmann, Christian; McElwain, Michael; Tamura, Motohide

2014-06-01

98

The Association of Management and the International Association of Management (AoM / IAoM)  

NSDL National Science Digital Library

The Association of Management and the International Association of Management (AoM/IAoM), publisher of the Journal of Management Systems (JMS), recently held its 16th Annual Conference in Chicago, Illinois to promote growth in management research and practice. AoM/IAoM is a non-profit organization of academicians and management practitioners, with divisions ranging from organizational and human resources to information systems and technology. Separate listervs exist for each division, and AoM/IAoM membership, publication, and conference information is available online.

1998-01-01

99

Determination of Metallosis after AO Plate Osteosynthesis by Means of Instrumental Neutron Activation Analysis.  

National Technical Information Service (NTIS)

The instrumental neutron activation analysis was used to determine metallosis after osteosynthesis in 11 samples of contact tissues and 6 samples of fascial tissues by means of AO-plates made of stainless steel. The concentrations of the elements specific...

G. Blettenberg

1975-01-01

100

Status update and closed-loop performance of the Magellan adaptive optics VisAO camera  

NASA Astrophysics Data System (ADS)

We present laboratory results of the closed-loop performance of the Magellan Adaptive Optics (AO) Adaptive Secondary Mirror (ASM), pyramid wavefront sensor (PWFS), and VisAO visible adaptive optics camera. The Magellan AO system is a 585-actuator low-emissivity high-throughput system scheduled for first light on the 6.5 meter Magellan Clay telescope in November 2012. Using a dichroic beamsplitter near the telescope focal plane, the AO system will be able to simultaneously perform visible (500-1000 nm) AO science with our VisAO camera and either 10 ?m or 3-5 ?m science using either the BLINC/MIRAC4 or CLIO cameras, respectively. The ASM, PWS, and VisAO camera have undergone final system tests in the solar test tower at the Arcetri Institute in Florence, Italy, reaching Strehls of 37% in i'-band with 400 modes and simulated turbulence of 14 cm ro at v-band. We present images and test results of the assembled VisAO system, which includes our prototype advanced Atmospheric Dispersion Corrector (ADC), prototype calcite Wollaston prisms for SDI imaging, and a suite of beamsplitters, filters, and other optics. Our advanced ADC performs in the lab as designed and is a 58% improvement over conventional ADC designs. We also present images and results of our unique Calibration Return Optic (CRO) test system and the ASM, which has successfully run in closedloop at 1kHz. The CRO test is a retro reflecting optical test that allows us to test the ASM off-sky in close-loop using an artificial star formed by a fiber source.

Kopon, Derek; Close, Laird M.; Males, Jared; Gasho, Victor; Morzinski, Katie; Follette, Katherine

2012-07-01

101

Keck AO survey of Io global volcanic activity between 2 and 5 ?m  

Microsoft Academic Search

We present in this Keck AO paper the first global high angular resolution observations of Io in three broadband near-infrared filters: Kc (2.3 ?m), Lp (3.8 ?m), and Ms (4.7 ?m). The Keck AO observations are composed of 13 data sets taken during short time intervals spanning 10 nights in December, 2001. The MISTRAL deconvolution process, which is specifically aimed

F. Marchis; D. Le Mignant; F. H. Chaffee; A. G. Davies; S. H. Kwok; R. Prangé; I. de Pater; P. Amico; R. Campbell; T. Fusco; R. W. Goodrich; A. Conrad

2005-01-01

102

An improved model with bending of laser beam for satellite-to-ground AO laser communication  

NASA Astrophysics Data System (ADS)

Correcting scintillation for a slant path with adaptive optics (AO) has been studied. However, the models for solving this problem are all to treat the ray track as a straight line. Based on the engineering practical environment, in a low-earth-orbit (LEO) satellite-to-ground laser communication link, the properties of laser beam bending in the slant path will be studied in this paper, and the novel amendatory model of correcting the scintillation with AO will be presented.

Rong, Jian; Li, Fang; Zhong, Xiao-chun; Ding, Xue-ke; Gui, Guan

2007-11-01

103

Defining reference turbulence profiles for E-ELT AO performance simulations  

NASA Astrophysics Data System (ADS)

ELT sites have been chosen after many years of site evaluation with various atmospheric turbulence profilers. ELT instrument planners are expecting reference profiles as input to the AO instrument performance estimators. It appears however that, for some AO modes like LTAO, the requirements exceed the available products in terms of altitude resolution. We explore the possibility of mixing long term statistics at low altitude resolution with high resolution data collected during short term campaigns to produce representative profiles

Sarazin, Marc; Le Louarn, Miska; Ascenso, Joana; Lombardi, Giancluca; Navarrete, Julio

2013-12-01

104

Enabling technologies for visible adaptive optics: the Magellan adaptive secondary VisAO camera  

Microsoft Academic Search

Since its beginnings, diffraction-limited ground-based adaptive optics (AO) imaging has been limited to wavelengths in the near IR (lambda>1mum) and longer. Visible AO (lambda>1mum) has proven to be difficult because shorter wavelengths require wavefront correction on very short spatial and temporal scales. The pupil must be sampled very finely, which requires dense actuator spacing and fine wavefront sampling with large

Derek Kopon; Jared Males; Laird M. Close; Victor Gasho

2009-01-01

105

Enabling Technologies for Visible Adaptive Optics: The Magellan Adaptive Secondary VisAO Camera  

Microsoft Academic Search

Since its beginnings, diffraction-limited ground-based adaptive optics (AO)\\u000aimaging has been limited to wavelengths in the near IR ({\\\\lambda} > 1 micron)\\u000aand longer. Visible AO ({\\\\lambda} < 1 micron) has proven to be difficult\\u000abecause shorter wavelengths require wavefront correction on very short spatial\\u000aand temporal scales. The pupil must be sampled very finely, which requires\\u000adense actuator spacing

Derek Kopon; Jared R. Males; Laird M. Close; Victor Gasho

2010-01-01

106

A computa»c~ao numerica como ferramenta para o professor de F¶‡sica do Ensino Medio  

Microsoft Academic Search

A proposta deste trabalhoe apresentar ao professor de F¶‡sica do ensino medio uma forma de empregar recur- sos computacionais para esclarecer e aprofundar conceitos de F¶‡sica que s~ao explorados de forma limitada por n~ao se poder recorrer ao Calculo Diferencial e Integral. O p^endulo simplese usado como prototipo para o trata- mento sugerido. Mostramos que apenas com o aux¶‡lio de

Augusto Cesar; Claudio Gon; Marcus Vinicius; Tovar Costa

107

Building a reliable, scalable and affordable RTC for AO instruments on ELTs  

NASA Astrophysics Data System (ADS)

Addressing the unprecedented amount of computing power needed by the ELTs AO instruments real-time controllers (RTC) is one of the key technological developments required for the design of the next generation AO systems. Throughput oriented architectures such as GPUs, providing orders of magnitude greater computational performance than high-end CPUs, have recently appeared as attractive and economically viable candidates since the fast emergence of devices capable of general purpose computing. However, using for real-time applications a I/0 device which cannot be scheduled nor controlled internally by the operating system but is sent commands through a closed source driver comes with a number of challenges. Building on the experience of almost real-time end-to-end simulations using GPUs, and relying on the development of the COMPASS platform, a unified and optimized framework for AO simulations and real-time control, our team has engaged into the development of a scalable, heterogeneous GPU-based prototype for an AO RTC. In this paper, we review the main challenges arising when utilizing GPUs in real-time systems for AO and rank them in terms of impact significance and available solutions. We present our strategy, to mitigate these issues including the general architecture of our prototype, the real-time core and additional dedicated components for data acquisition and distribution. Finally, we discuss the expected performance in terms of latency and jitter on the basis of realistic benchmarks and focusing on the dimensioning of the MICADO AO module RTC.

Gratadour, Damien; Sevin, Arnaud; Perret, Denis; Brule, Julien

2013-12-01

108

Decolorization of the AO24 azo dye and reduction of toxicity and genotoxicity in trickling biofilters.  

PubMed

Acid Orange 24 (AO24) dye was degraded in a trickling biofilter packed with peat and wood chips and inoculated with biomass from a petrochemical industry wastewater system. Different operating strategies were tested; in the first stage, two biofilters were operated independently--one non-aerated biofilter (passive) and the other with aeration-subsequently, the systems were operated serially, and effluent from the non-aerated biofilter was fed to the biofilter with aeration. This treatment train was used to test three different filtration velocities--0.141, 0.282, and 0.423 m/d. The results show that, when operating the systems with a dye charge of 0.035 kg AO24 m2/d and treating the effluent in a single step, good removal efficiencies of AO24 (95 and 89%), COD (63 and 53%), and acute toxicity (63 and 78%) were obtained in both biofilters (with and without air), although mutagenic and potentially carcinogenic intermediary compounds were not removed, because genotoxicity exhibits values higher than 2.0 units for the mutation rate. When using the non-aerated biofilter/aerated biofilter treatment train, it is possible to treat a dye charge 3 times greater (0.106 kg AO24 m2/d) and efficiently remove 98% AO24, 76% COD, 100% acute toxicity, and 100% genotoxicity, which indicates that, with this biological system, an advanced degree of biotransformation and mineralization of the azo dye AO24 is achieved. PMID:21449472

Garzóón-Zúñga, Marco A; Sandoval-Villasana, Ana M; Moeller-Chávez, Gabriela E

2011-02-01

109

Robo-AO: Initial results from the first autonomous laser guide star adaptive optics instrument  

NASA Astrophysics Data System (ADS)

Large surveys, such as the Kepler mission and Palomar Transient Factory, are discovering upwards of thousands of objects which require further characterization at angular resolutions significantly finer than normally allowed by atmospheric seeing. The demands on precious space-based observatories (i.e. Hubble Space Telescope) and large telescopes with adaptive optics (AO) systems (i.e. Keck, VLT, Gemini) leave them generally unavailable for high angular resolution surveys of more than a few hundred targets at a time. To address the gap between scientific objects and available telescopes, we have developed Robo-AO, the first robotic laser AO system, as an economical and efficient imaging instrument for the more readily available 1-3 m class telescopes. The Robo-AO system system demonstrates angular resolutions approaching the visible diffraction limit of the Palomar 60-inch telescope. Observations of over 200 stellar objects per night have routinely been performed, with target-to-target observation overheads of less than 1.5 minutes. Scientific programs requiring high-resolution follow-up characterization of several thousands of targets can thus be executed in mere weeks, and Robo-AO has already completed the three largest AO surveys to date.

Riddle, R.; Baranec, C.; Law, N. M.; Ramaprakash, A. N.; Tendulkar, S.; Hogstrom, K.; Bui, K.; Burse, M.; Chordia, P.; Das, H.; Dekany, R.; Kulkarni, S.; Punnadi, S.; Smith, R.

2014-03-01

110

Annual report 1977. [Univ. of Minnesota  

SciTech Connect

This is the final Annual Report of the general operation of the Williams Laboratory of Nuclear Physics of the University of Minnesota. Because the report prepared in 1976 was not widely circulated, this report contains summaries of research conducted during the period from the fall of 1975 through the summer of 1977. This report begins with a brief history of the Williams Laboratory and a synopsis of the various lines of research carried on in the laboratory since the MP Tandem Van de Graaff machine was placed in operation in 1966. The major portion of the report describes the results of research programs completed or in progress during the past two years. Information is presented about modifications to the Van de Graaff machine and the on-line computer, which resulted in improved performance, and there are brief descriptions of a source for producing a triton beam and a heavy-ion counter for the magnetic spectrometer. An appendix contains a list of laboratory personnel during the time covered by this report, a list of advanced degrees granted to graduate students, and a list of recent reports and publications. (RWR)

Not Available

1977-12-01

111

L'univers clos de Stephen Hawking.  

NASA Astrophysics Data System (ADS)

Einstein had curved space, Hawking will curve time. Hawking's universe is a closed model, a 4-sphere, which encloses its own space and its own time. Nothing exists outside and without any time overlapping this 4-sphere, it cannot have a beginning, an evolution or an end. It only is. But such an absolute existence of this type of universe implies that its 3-dimensional sclices - which are our physical space - cannot have the same absolute state of being. Thus, they are necessarily transitory, with a beginning and an end, in time which is the 4th remaining dimension of the 4-sphere. Hawking absolute universe is the cause of time.

Andrillat, H.

112

[Activities of Psychology Dept., California Univ.  

NASA Technical Reports Server (NTRS)

We have completed two studies during the grant period, with manuscripts published or ready for submission for publication: (1) Dual adaptation and adaptive generalization in the human vestibuloocular reflex and (2) Frequency vs. acceleration specificity in human VOR adaptation. In the 1st study two studies examined the possibility that rotational VOR plasticity is subject to dual adaptation and adaptive generalization. Subjects in the experimental condition were exposed to an altered visual-vestibular environment for about four minutes every day for five consecutive days. The working hours between these testing sessions constituted re-exposure to the normal visual environment. Thus, subjects were repeatedly adapting and re-adapting to both environments which is a condition designed to produce dual adaptation. In each training session a measure of baseline VOR gain was obtained (in the dark). A small laser spot (the only visual stimulus) was systematically moved in the same direction as the subject's head, but by half the angle of rotation (target/head gain = 0.5). This resulted in adaptation values relativized to the non-adapted gain of each subject. These values were then analyzed using an analysis of variance with day and session (within a day) as factors. In the 2nd study human VOR adaption has been assumed to be frequency specific, despite the fact that the semicircular canals are simulated by rotational acceleration and not frequency per se.

Bridgeman, Bruce

1998-01-01

113

Requirements Modeling with the Aspect-oriented User Requirements Notation (AoURN): A Case Study  

NASA Astrophysics Data System (ADS)

The User Requirements Notation (URN) is a recent ITU-T standard that supports requirements engineering activities. The Aspect-oriented URN (AoURN) adds aspect-oriented concepts to URN, creating a unified framework that allows for scenario-based, goal-oriented, and aspect-oriented modeling. AoURN is applied to the car crash crisis management system (CCCMS), modeling its functional and non-functional requirements (NFRs). AoURN generally models all use cases, NFRs, and stakeholders as individual concerns and provides general guidelines for concern identification. AoURN handles interactions between concerns, capturing their dependencies and conflicts as well as the resolutions. We present a qualitative comparison of aspect-oriented techniques for scenario-based and goal-oriented requirements engineering. An evaluation carried out based on the metrics adapted from literature and a task-based evaluation suggest that AoURN models are more scalable than URN models and exhibit better modularity, reusability, and maintainability.

Mussbacher, Gunter; Amyot, Daniel; Araújo, João; Moreira, Ana

114

Frame selection techniques for the Magellan adaptive optics VisAO camera  

NASA Astrophysics Data System (ADS)

The Magellan AO system will begin commissioning in early 2012. Its VisAO camera will provide 20 mas FWHM images with mean Strehl ratios of ~ 0.2 in R band on a 6.5m telescope. Depending on seeing conditions, Strehl ratio may reach temporary peaks as high as 0.5 at these wavelengths. To take advantage of these brief periods of high performance, we plan to adopt lucky imaging style data taking and reduction techniques. As part of this effort we have developed a novel real-time frame selection technique, which will use AO system telemetry and a fast shutter to limit CCD exposure to these very brief moments of higher Strehl. Here we describe the expected benefits of our frame selection techniques in various operating modes. We also present the results of laboratory characterization of the shutter, and describe the performance of predictive algorithms used to control it.

Males, Jared R.; Close, Laird M.; Kopon, Derek; Gasho, Victor; Follette, Katherine

2010-07-01

115

[TRAIL inhibits proliferation and promotes apoptosis of 3AO ovarian cancer cells].  

PubMed

Objective To investigate the effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on the proliferation of ovarian carcinoma 3AO cells in vitro and its molecular mechanism. Methods Ovarian carcinoma 3AO cells were incubated with 12.5, 25.0, 50.0 ng/mL TRAIL proteins for 72 hours, respectively. At 24, 48 and 72 hours, the cells were collected to observe the morphological change under an inverted microscope, detect the cell proliferation using methyl thiazolyl tetrazolium (MTT) assay, the apoptosis rate and cell cycle using flow cytometry (FCM), the morphological features of apoptotic cells using TdT-mediated-dUTP nick end labeling (TUNEL) and the expression of caspase-3 protein using Western blotting. Results The growth of 3AO cells was inhibited by different concentrations of TRAIL (P<0.05). Morphological change of 3AO cells was clearly observed. TRAIL protein at 25 and 50 ng/mL significantly induced 3AO cell apoptosis and cell cycle arrest. With the treatment time went by, the percentage of cells at G1 phase increased and cells at S and G2/M phase decreased. The expression of caspase-3 protein was raised by TRAIL. No significant differences were noted in the apoptosis rate and the expression of caspase-3 protein between the 25 and 50 ng/mL TRAIL groups (P>0.05). Conclusion TRAIL protein could promote the apoptosis of 3AO cells through inhibiting cell growth cycle, blocking DNA synthesis and activating caspase-3. PMID:24796736

Zhang, Shaohua; Liu, Kaige; Cheng, Biping; Gao, Qian; Wang, Li; Yang, Xiaofeng

2014-05-01

116

Up-Regulated Expression of AOS-LOXa and Increased Eicosanoid Synthesis in Response to Coral Wounding  

PubMed Central

In octocorals, a catalase–like allene oxide synthase (AOS) and an 8R-lipoxygenase (LOX) gene are fused together encoding for a single AOS-LOX fusion protein. Although the AOS-LOX pathway is central to the arachidonate metabolism in corals, its biological function in coral homeostasis is unclear. Using an acute incision wound model in the soft coral Capnella imbricata, we here test whether LOX pathway, similar to its role in plants, can contribute to the coral damage response and regeneration. Analysis of metabolites formed from exogenous arachidonate before and after fixed time intervals following wounding indicated a significant increase in AOS-LOX activity in response to mechanical injury. Two AOS-LOX isoforms, AOS-LOXa and AOS-LOXb, were cloned and expressed in bacterial expression system as active fusion proteins. Transcription levels of corresponding genes were measured in normal and stressed coral by qPCR. After wounding, AOS-LOXa was markedly up-regulated in both, the tissue adjacent to the incision and distal parts of a coral colony (with the maximum reached at 1 h and 6 h post wounding, respectively), while AOS-LOXb was stable. According to mRNA expression analysis, combined with detection of eicosanoid product formation for the first time, the AOS-LOX was identified as an early stress response gene which is induced by mechanical injury in coral.

Lohelaid, Helike; Teder, Tarvi; Toldsepp, Kadri; Ekins, Merrick; Samel, Nigulas

2014-01-01

117

Gas Permeability of Foam Films Stabilized by an Alpha Olefin Sulfonate (AOS) Surfactant  

NASA Astrophysics Data System (ADS)

In the present study we examine the basic properties of single foam films prepared from alpha (C14-C16) olefin sulfonate (AOS). The film thickness was measured as a function of the electrolyte (NaCl) concentration. Special attention was focused on the gas permeability of the films defined by permeability coefficient kf(cm/s). The influence of the film thickness and surfactant adsorption on kf was followed. Supporting surface tension experiments at different surfactant concentrations were performed to obtain the adsorption of AOS at air/aqueous solution interface at different surfactant and salt concentrations.

Farajzadeh, R.; Krastev, R.; Zitha, P. L. J.

2008-07-01

118

An eight-octant phase-mask coronagraph for the Subaru coronagraphic extreme AO (SCExAO) system: system design and expected performance  

NASA Astrophysics Data System (ADS)

An eight-octant phase-mask (EOPM) coronagraph is one of the highest performance coronagraphic concepts, and attains simultaneously high throughput, small inner working angle, and large discovery space. However, its application to ground-based telescopes such as the Subaru Telescope is challenging due to pupil geometry (thick spider vanes and large central obstruction) and residual tip-tilt errors. We show that the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system, scheduled to be installed onto the Subaru Telescope, includes key technologies which can solve these problems. SCExAO uses a spider removal plate which translates four parts of the pupil with tilted plane parallel plates. The pupil central obstruction can be removed by a pupil remapping system similar to the PIAA optics already in the SCExAO system, which could be redesigned with no amplitude apodization. The EOPM is inserted in the focal plane to divide a stellar image into eight-octant regions, and introduces a ?-phase difference between adjacent octants. This causes a self-destructive interference inside the pupil area on a following reimaged pupil plane. By using a reflective mask instead of a conventional opaque Lyot stop, the stellar light diffracted outside the pupil can be used for a coronagraphic low-order wave-front sensor to accurately measure and correct tip-tilt errors. A modified inverse-PIAA system, located behind the reimaged pupil plane, is used to remove off-axis aberrations and deliver a wide field of view. We show that this EOPM coronagraph architecture enables high contrast imaging at small working angle on the Subaru Telescope. Our approach could be generalized to other phase-mask type coronagraphs and other ground-based telescopes.

Murakami, Naoshi; Guyon, Olivier; Martinache, Frantz; Matsuo, Taro; Yokochi, Kaito; Nishikawa, Jun; Tamura, Motohide; Kurokawa, Takashi; Baba, Naoshi; Vogt, Frédéric; Garrel, Vincent; Yoshikawa, Takashi

2010-07-01

119

The Hohmann bunionectomy utilizing A-O screw fixation: a preliminary report.  

PubMed

A 14-month retrospective study was performed on 11 patients (15 feet) who had corrective bunion surgery utilizing a modified A-O Hohmann bunionectomy. The study involved radiographic evaluation, range of motion measurements, and a subjective questionnaire. The results of the study suggest that the procedure is very effective in correcting mild to moderate bunion deformities. PMID:6470424

Warrick, J P; Edelman, R

1984-01-01

120

GPS-Based Navigation And Orbit Determination for the AMSAT AO-40 Satellite  

NASA Technical Reports Server (NTRS)

The AMSAT OSCAR-40 (AO-40) spacecraft occupies a highly elliptical orbit (HEO) to support amateur radio experiments. An interesting aspect of the mission is the attempted use of GPS for navigation and attitude determination in HEO. Previous experiences with GPS tracking in such orbits have demonstrated the ability to acquire GPS signals, but very little data were produced for navigation and orbit determination studies. The AO-40 spacecraft, flying two Trimble Advanced Navigation Sensor (TANS) Vector GPS receivers for signal reception at apogee and at perigee, is the first to demonstrate autonomous tracking of GPS signals from within a HEO with no interaction from ground controllers. Moreover, over 11 weeks of total operations as of June 2002, the receiver has returned a continuous stream of code phase, Doppler, and carrier phase measurements useful for studying GPS signal characteristics and performing post-processed orbit determination studies in HEO. This paper presents the initial efforts to generate AO-40 navigation solutions from pseudorange data reconstructed from the TANS Vector code phase, as well as to generate a precise orbit solution for the AO-40 spacecraft using a batch filter.

Davis, George; Moreau, Michael; Carpenter, Russell; Bauer, Frank

2002-01-01

121

Development of vibration source requirements for TMT to ensure AO performance  

NASA Astrophysics Data System (ADS)

In order for TMT to deliver the required adaptive optics (AO) image quality, vibrationsources throughout the observatory need to be understood and their resulting optical response characterized.The sensitivity to vibration has been determined using a finite element model of the telescopestructure and mirror segments coupled to optical models. Frequency dependent models of the AO, activeoptics and mount control systems are included allowing end-to-end assessment of vibration sourceson AO-corrected image quality; future work will improve estimates of the propagation of vibrationsfrom equipment in the summit support building and enclosure to the telescope pier. Modeling separatelypredicts effects on image jitter caused by relative rigid body motion of main optical elements, and thedynamic motion of the 492 individual primary mirror segments. These results have been used to developallocated requirements on source amplitudes at different locations and as a function of frequency, whichwill lead to subsystem design requirements (e.g. for isolation systems at various locations both in thesupport building and enclosure and on the telescope structure). In order to meet an aggressive target forthis contribution to the AO error budget, vibration forces on the telescope itself must be limited to a fewNewtons in the most sensitive frequency range of 5-20Hz; larger forces of order 100N can be toleratedfor equipment mounted off the telescope in the summit facilities building.

MacMartin, Doug; Thompson, Hugh

2013-12-01

122

ALGO NOVO NO MUNDO EMPRESARIAL: DO TURBILHÃO DE DADOS AO REQUINTE DA INTELIGÊNCIA  

Microsoft Academic Search

RESUMO 1. INTRODUÇÃO Na Sociedade do Conhecimento, as organizações precisam aprender a administrar sua inteligência empresarial. Esta pode representar um importante diferencial em relação aos concorrentes, e, dessa forma, não deve ser desprezada ou subestimada. No mundo atual, altamente competitivo, as organizações precisam estar atentas à concorrência, sob pena de perder espaço no mercado. Desse modo, fica cada vez mais

Simone Bastos Paiva; Edward de Bono

2002-01-01

123

LDEF (Prelaunch), AO180 : The Effect of Space Environment Exposure on the Properties of Polymer Matr  

NASA Technical Reports Server (NTRS)

LDEF (Prelaunch), AO180 : The Effect of Space Environment Exposure on the Properties of Polymer Matrix Composite Materials, Tray D12 The prelaunch photograph shows the positions of the three (3) LDEF experiments in a three (3) inch deep tray. The AO023 experiment is located in the left one third (1/3rd) section, the AO180 experiment occupies the center one third (1/3rd) section plus the lower one half (1/2) of the right section and the AO019 experiment is shown in the top right section of the tray. The Polymer Matrix Composite Materials experiment is an active experiment that occupies one half (1/2) of the tray's exposed surface area and contains a data acquisition and recording system. The experiment consist of sixty-two (62) composite tubes with aluminum end fittings, forty-five (45) flat composite coupons with aluminum retainer blocks, and one (1) stainless steel calibration tube. The fasteners used to assemble the experiment were non-magnetic stainless steel. The test samples were manufactured from different epoxy matrix composites containing carbon, boron and aramide (Kevlar) reinforcements. A custom data acquisition system was designed to record and store the data from sixteen (16) thermal/strain gauges on a magnetic tape cassette. The data system and batteries to power the system are located beneath the aluminum base plates.

1984-01-01

124

Performance of a MEMS-based AO-OCT system using Fourier Reconstruction  

SciTech Connect

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution (3.5 {micro}m isotropic), 3-D images of the retina. The AO-OCT system at UC Davis has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction and a 140-actuator Boston Micromachines DM for high-order correction. Developments to improve performance or functionality of the instrument are on-going. Based on previous work in system characterization we have focused on improved AO control. We present preliminary results and remaining challenges for a newly implemented Fourier transform reconstructor (FTR). The previously reported error budget analysis is also reviewed and updated, with consideration of how to improve both the amount of residual error and the robustness of the system. Careful characterization of the AO system will lead to improved performance and inform the design of future systems.

Evans, J; Zawadzki, R; Jones, S; Olivier, S; Werner, J S

2009-01-21

125

Performance of a MEMS-based AO-OCT system using Fourier reconstruction  

NASA Astrophysics Data System (ADS)

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution (3.5 ?m isotropic), 3-D images of the retina. The AO-OCT system at UC Davis has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction and a 140-actuator Boston Micromachines DM for high-order correction. Developments to improve performance or functionality of the instrument are on-going. Based on previous work in system characterization we have focused on improved AO control. We present preliminary results and remaining challenges for a newly implemented Fourier transform reconstructor (FTR). The previously reported error budget analysis is also reviewed and updated, with consideration of how to improve both the amount of residual error and the robustness of the system. Careful characterization of the AO system will lead to improved performance and inform the design of future systems.

Evans, Julia W.; Zawadzki, Robert J.; Jones, Steve; Olivier, Scot; Werner, John S.

2009-02-01

126

Improved tilt sensing in an LGS-based tomographic AO system based on instantaneous PSF estimation  

NASA Astrophysics Data System (ADS)

Laser guide star (LGS)-based tomographic AO systems, such as Multi-Conjugate AO (MCAO), Multi-Object AO (MOAO) and Laser Tomography AO (LTAO), require natural guide stars (NGSs) to sense tip-tilt (TT) and possibly other low order modes, to get rid of the LGS-tilt indetermination problem. For example, NFIRAOS, the first-light facility MCAO system for the Thirty Meter Telescope requires three NGSs, in addition to six LGSs: two to measure TT and one to measure TT and defocus. In order to improve sky coverage, these NGSs are selected in a so-called technical field (2 arcmin in diameter for NFIRAOS), which is much larger than the on-axis science field (17x17 arcsec for NFIRAOS), on which the AO correction is optimized. Most times, the NGSs are far off-axis and thus poorly corrected by the high-order AO loop, resulting in spots with low contrast and high speckle noise. Accurately finding the position of such spots is difficult, even with advanced methods such as matched-filtering or correlation, because these methods rely on the knowledge of an average spot image, which is quite different from the instantaneous spot image, especially in case of poor correction. This results in poor tilt estimation, which, ultimately, impacts sky coverage. We propose to improve the estimation of the position of the NGS spots by using, for each frame, a current estimate of the instantaneous spot profile instead of an average profile. This estimate can be readily obtained by tracing wavefront errors in the direction of the NGS through the turbulence volume. The latter is already computed by the tomographic process from the LGS measurements as part of the high order AO loop. Computing such a wavefront estimate has actually already been proposed for the purpose of driving a deformable mirror (DM) in each NGS WFS, to optically correct the NGS spot, which does lead to improved centroiding accuracy. Our approach, however, is much simpler, because it does not require the complication of extra DMs, which would need to be driven in open-loop. Instead, it can be purely implemented in software, does not increase the real-time computational burden significantly, and can still provide a significant improvement in tilt measurement accuracy, and therefore in sky-coverage. In this paper, we illustrate the benefit of this new tilt measurement strategy in the specific case of NFIRAOS, under various observing conditions, in comparison with the more traditional approaches that ignore the instantaneous variations of the NGS spot profiles.

Veran, Jean-Pierre

2013-12-01

127

Increase in BrAO1 gene expression and aldehyde oxidase activity during clubroot development in Chinese cabbage (Brassica rapa L.).  

PubMed

SUMMARY In clubroot disease, gall formation is induced by infection with the obligate biotroph Plasmodiophora brassicae due to increased levels of auxins and cytokinins. Because aldehyde oxidase (AO) may be involved in auxin biosynthesis in plants, we isolated two AO genes (BrAO1 and BrAO2) from Chinese cabbage (Brassica rapa ssp. pekinensis cv. Muso), which are the most similar to AAO1 among Arabidopsis AO genes, and examined their expressions during clubroot development. The expression of BrAO1 was enhanced in inoculated roots from 15 days post-inoculation (dpi) when visible clubroots were still undetectable. Thereafter, BrAO1 expression increased with clubroot development compared with uninoculated roots, although BrAO2 expression was repressed. In situ hybridization revealed that BrAO1 was strongly expressed in tissues that were invaded by immature plasmodia at 35 dpi, suggesting that BrAO1 expression was enhanced by the pathogen in order to establish its pathogenesis. In addition, we detected AO activity, as evidenced by the occurrence of at least six bands (BrAO-a to BrAO-f) in the roots of Chinese cabbage using an active staining method with benzaldehyde and indlole-3-aldehyde as the substrate. Coincidental with BrAO1 expression, the signals of BrAO-a and BrAO-d increased with inoculation by P. brassicae during clubroot development compared with healthy roots, resulting in an increase in total AO activity. By contrast, the band BrAO-b decreased post-inoculation, in parallel with the expression of BrAO2. The other bands of activity were not clearly influenced by the infection. Based on these results, we discuss the involvement of AO in auxin-overproduction during clubroot development in Chinese cabbage. PMID:20507442

Ando, Sugihiro; Tsushima, Seiya; Tagiri, Akemi; Kamachi, Shinichiro; Konagaya, Ken-Ichi; Hagio, Takashi; Tabei, Yutaka

2006-07-01

128

Effect of Ambrotose AO® on resting and exercise-induced antioxidant capacity and oxidative stress in healthy adults  

Microsoft Academic Search

BACKGROUND: The purpose of this investigation was to determine the effects of a dietary supplement (Ambrotose AO®) on resting and exercise-induced blood antioxidant capacity and oxidative stress in exercise-trained and untrained men and women. METHODS: 25 individuals (7 trained and 5 untrained men; 7 trained and 6 untrained women) received Ambrotose AO® (4 capsules per day = 2 grams per

Richard J Bloomer; Robert E Canale; Megan M Blankenship; Kelsey H Fisher-Wellman

2010-01-01

129

Systematic structure modifications of imidazo[1,2-a]pyrimidine to reduce metabolism mediated by aldehyde oxidase (AO).  

PubMed

N-{trans-3-[(5-Cyano-6-methylpyridin-2-yl)oxy]-2,2,4,4-tetramethylcyclobutyl}imidazo[1,2-a]pyrimidine-3-carboxamide (1) was recently identified as a full antagonist of the androgen receptor, demonstrating excellent in vivo tumor growth inhibition in castration-resistant prostate cancer (CRPC). However, the imidazo[1,2-a]pyrimidine moiety is rapidly metabolized by aldehyde oxidase (AO). The present paper describes a number of medicinal chemistry strategies taken to avoid the AO-mediated oxidation of this particular system. Guided by an AO protein structure-based model, our investigation revealed the most probable site of AO oxidation and the observation that altering the heterocycle or blocking the reactive site are two of the more effective strategies for reducing AO metabolism. These strategies may be useful for other drug discovery programs. PMID:21955208

Linton, Angelica; Kang, Ping; Ornelas, Martha; Kephart, Susan; Hu, Qiyue; Pairish, Mason; Jiang, Ying; Guo, Chuangxing

2011-11-10

130

Computer simulations and real-time control of ELT AO systems using graphical processing units  

NASA Astrophysics Data System (ADS)

The adaptive optics (AO) simulations at the Thirty Meter Telescope (TMT) have been carried out using the efficient, C based multi-threaded adaptive optics simulator (MAOS, http://github.com/lianqiw/maos). By porting time-critical parts of MAOS to graphical processing units (GPU) using NVIDIA CUDA technology, we achieved a 10 fold speed up for each GTX 580 GPU used compared to a modern quad core CPU. Each time step of full scale end to end simulation for the TMT narrow field infrared AO system (NFIRAOS) takes only 0.11 second in a desktop with two GTX 580s. We also demonstrate that the TMT minimum variance reconstructor can be assembled in matrix vector multiply (MVM) format in 8 seconds with 8 GTX 580 GPUs, meeting the TMT requirement for updating the reconstructor. Analysis show that it is also possible to apply the MVM using 8 GTX 580s within the required latency.

Wang, Lianqi; Ellerbroek, Brent

2012-07-01

131

Results using the AO hook plate for dislocations of the acromioclavicular joint.  

PubMed

The AO Hook plate has been used for stabilization of acromioclavicular joint dislocations. We present our experience of this newly introduced device in a general hospital, since there are not many papers in the literature reporting on this. A total of 16 patients were treated with the AO Hook plate between November 2001 and November 2003 at Princess Alexandra Hospital in Harlow, UK. For functional assessment 6 months after removal of the plate, the constant score and the pain visual analogue score were used. The pain visual analogue score ranged from 0 to 6 (mean: 0.87) and the constant score ranged from 78 to 100 (mean: 96.4). In one instance, a patient developed instability after removal of the plate. The use of this device results in excellent functional outcome for the treatment of acromioclavicular joint dislocations. PMID:18803467

Koukakis, Athanasios; Manouras, Andreas; Apostolou, Constantinos D; Lagoudianakis, Emmanuel; Papadima, Artemisia; Triantafillou, Christos; Korres, Dimitrios; Allen, Paul W; Amini, Alexander

2008-09-01

132

Villages: an on-sky visible wavelength astronomy AO experiment using a MEMS deformable mirror  

Microsoft Academic Search

The MEMS-AO\\/Villages project consists of a series of on-sky experiments that will demonstrate key new technologies for the next generation of adaptive optics systems for large telescopes. One of our first goals is to demonstrate the use of a micro-electro-mechanical systems (MEMS) deformable mirror as the wavefront correcting element. The system is mounted the 1-meter Nickel Telescope at the UCO\\/Lick

Donald Gavel; Scott Severson; Brian Bauman; Daren Dillon; Marco Reinig; Christopher Lockwood; Dave Palmer; Kathleen Morzinski; Mark Ammons; Elinor Gates; Bryant Grigsby

2008-01-01

133

The Incidence of Hip Fracture in Four Asian Countries: The Asian Osteoporosis Study (AOS)  

Microsoft Academic Search

:   The Asian Osteoporosis Study (AOS) is the first multicenter study to document and compare the incidence of hip fracture in\\u000a four Asian countries. Hospital discharge data for the year 1997 were obtained for the Hong Kong SAR, Singapore, Malaysia and\\u000a Thailand (Chiang Mai). The number of patients who were 50 years of age and older and who were discharged

E. M. C. Lau; J. K. Lee; P. Suriwongpaisal; S. M. Saw; S. Das De; A. Khir; P. Sambrook

2001-01-01

134

Enabling technologies for visible adaptive optics: the Magellan adaptive secondary VisAO camera  

NASA Astrophysics Data System (ADS)

Since its beginnings, diffraction-limited ground-based adaptive optics (AO) imaging has been limited to wavelengths in the near IR (?>1?m) and longer. Visible AO (?>1?m) has proven to be difficult because shorter wavelengths require wavefront correction on very short spatial and temporal scales. The pupil must be sampled very finely, which requires dense actuator spacing and fine wavefront sampling with large dynamic range. In addition, atmospheric dispersion is much more significant in the visible than in the near-IR. Imaging over a broad visible band requires a very good Atmospheric Dispersion Corrector (ADC). Even with these technologies, our AO simulations using the CAOS code, combined with the optical and site parameters for the 6.5m Magellan telescope, demonstrate a large temporal variability of visible (?=0.7?m) Strehl on timescales of 50 ms. Over several hundred milliseconds, the visible Strehl can be as high at 50% and as low as 10%. Taking advantage of periods of high Strehl requires either the ability to read out the CCD very fast, thereby introducing significant amounts of read-noise, or the use of a fast asynchronous shutter that can block the low-Strehl light. Our Magellan VisAO camera will use an advanced ADC, a high-speed shutter, and our 585 actuator adaptive secondary to achieve broadband (0.5-1.0 ?m) diffraction limited images on the 6.5m Magellan Clay telescope in Chile at Las Campanas Observatory. These will be the sharpest and deepest visible direct images taken to date with a resolution of 17 mas, a factor of 2.7 better than the diffraction limit of the Hubble Space Telescope.

Kopon, Derek; Males, Jared; Close, Laird M.; Gasho, Victor

2009-08-01

135

A Method of Geospatial Modeling and Simulation Based on Geo-AO  

Microsoft Academic Search

The dynamic cognition or spatio-temporal simulation to geo-objects (geo-spatial objects) or phenomena' is always one of the principal difficulties owing to their dynamic complexity. To solve it to a certain extent, a new mechanism based on Geo-AO is proposed in this paper. First, the popular methods of geo-simulation are analysed and some existing problems are also summarized briefly. Then, geo-cognition

Jun Wang; Qingxiong Cui; Kun Yang

2008-01-01

136

Tomographic phase diversity for phase retrieval on wide-field AO systems  

NASA Astrophysics Data System (ADS)

Phase diversity is a commonly used technique to retrieve the wavefront at the focal plane. The usual algorithm involves two or more images of the same target with known phase changes like defocus. It has been shown to be very efficient at measuring on-axis the non-common path aberrations of classical AO systems. In this paper, we present an evolution of this algorithm towards tomographic measurements. This novel technique is dedicated to wide-field AO systems, allowing phase retrieval on multiple layers, conjugated at various altitudes. While the general grounds are very similar to classical phase diversity, the tomographic algorithm involves two or more images with known phase changes of several targets dispatched over the entire field of view. Regularization on the phase is usualy done by factorizing it on a basis of modes, traditionally Zernike polynomials. In this paper, we discuss the choice of a proper basis in the tomographic case and show that other basis such as disk harmonics are interesting alternatives in the case of real AO systems. We additionally propose two versions for this algorithm: an image-based and a Fourier-based both leading to comparable results. We finally present the results obtained on simulated data as well as on real data obtained on the Gemini MCAO system on which this algorithm has been used to estimate and compensate for non common path aberrations.

Gratadour, Damien; Rigaut, François

2011-09-01

137

ASSIST: development of a test-infrastructure for the VLT AO facility  

NASA Astrophysics Data System (ADS)

ASSIST - The Adaptive Secondary Setup and Instrument STimulator is a test setup to verify the operation of three elements of the VLT Adaptive Optics Facility, namely the Deformable Secondary Mirror (DSM) and the two AO systems using this DSM, the AO system for the visible light integral field spectrograph MUSE (GALACSI) and the AO system for the IR wide field imager HAWK-I (GRAAL). To support the testing of these elements, ASSIST will provide both an interferometry setup for testing the DSM as well as a full atmospheric turbulence simulator and star simulator to mimic the conditions at the telescope. To test the instruments using the DSM, the output beam is matched the output beam of the VLT telescope, including the correct exit-pupil and high-quality imaging and a similar hardware interface is provided. Since one of the modes to be verified is nearly diffraction limited, also the thermal and vibrational stability are very important, with strong constraints on both the mechanical as well as the optical design.

Stuik, Remko; Arsenault, Robin; Deep, Atul; Delabre, Bernard; Hallibert, Pascal; Jolissaint, Laurent; Hubin, Norbert; Kendrew, Sarah; Madec, Pierre-Yves; Paufique, Jerome; Stroebele, Stefan

2007-09-01

138

Microwelding of various metallic materials under ultravacuum (AO 138-10)  

NASA Technical Reports Server (NTRS)

The first finding from the AO 138-10 is that cold welding never occurred, and that microwelds didn't even affect the reference (presumably microweld prone) pairs of metals consisting of gold, silver, and chromium. The scientific disappointment from these results must be tempered by the notion of a static AO 138-10 experiment, reflecting the passive character of the global Long Duration Exposure Facility (LDEF) flight. Thus far, it has been theorized that cold welding results from the peeling of the oxide layer, that is formed in an earth environment, by the space environment since such a layer no longer grows in space. In fact, such stripping of the oxide layer supposes relative motion of the contacting materials. In the absence of such motion, as in this experiment, oxidation will preserve its integrity and continue to prevent microwelding. More bewildering is that there was no microwelding of the reference pairs. Even though AO 138-10 failed scientific expectations, as did the LDEF structure with cold welding, the positive, functional aspect to keep in mind is the safe operation of single-shot (appendage releasing and/or latching) mechanisms, unhindered by microwelding in a space vacuum, as now demonstrated by the statically representative pairs of materials. Other aspects of the experiment are discussed.

Assie, Jean Pierre; Conde, Eric

1991-01-01

139

An AO real-time control solution for ELT scale instrumentation and application to EAGLE  

NASA Astrophysics Data System (ADS)

EAGLE is a proposed multi-IFU instrument for the E-ELT, with a full multi-object AO system. Current baseline designs for this MOAO system include up to six laser guide stars and five natural guide stars. Twenty science channels will be corrected using a corresponding number of independent 84x84 actuator deformable mirrors, though the applied corrections will not be observed by the wavefront sensors. In addition to this, the E-ELT M4 mirror is also part of the AO system, and will operate in closed loop. One possible design for a real-time control system for EAGLE is presented here, based on the Durham AO Real-time Control platform (DARC). Using hardware that we have available, we will present performance results based on the implementation of a sub-set of EAGLE, a single IFU channel. This can then be replicated twenty times to obtain a full EAGLE real-time control system, since each channel is independent. We also consider the implementation of real-time control systems for other ELT instruments, and how far our approach can take us.

Basden, Alastair; Dipper, Nigel; Myers, Richard; Younger, Eddy

2012-07-01

140

Compilação de dados atômicos e moleculares do UV ao IV próximo para uso em síntese espectral  

NASA Astrophysics Data System (ADS)

Espectros sintéticos são utéis em uma grande variedade de aplicações, desde análise de abundâncias em espectros estelares de alta resolução ao estudo de populações estelares em espectros integrados. A confiabilidade de um espectro sintético depende do modelo de atmosfera adotado, do código de formação de linhas e da qualidade dos dados atômicos e moleculares que são determinantes no cálculo das opacidades da fotosfera. O nosso grupo no departamento de Astronomia no IAG tem utilizado espectros sintéticos há mais de 15 anos, em aplicações voltadas principalmente para a análise de abundâncias de estrelas G, K e M e populações estelares velhas. Ao longo desse tempo, as listas de linhas vieram sendo construídas e atualizadas continuamente, e alguns acréscimos recentes podem ser citados: Castilho (1999, átomos e moléculas no UV), Schiavon (1998, bandas moleculares de TiO) e Melendez (2001, átomos e moléculas no IV próximo). Com o intuito de calcular uma grade de espectros do UV ao IV próximo para uso no estudo de populações estelares velhas, se fazia necessário compilar e homogeneizar as diversas listas em apenas uma lista atômica e uma molecular. Nesse processo, a nova lista compilada foi correlacionada com outras bases de dados (NIST, Kurucz Database, O' Brian et al. 1991) para atualização dos parâmetros que caracterizam a transição atômica (comprimento de onda, log gf e potencial de excitação). Adicionalmente as constantes de interação C6 foram calculadas segundo a teoria de Anstee & O'Mara (1995) e artigos posteriores. As bandas moleculares de CH e CN foram recalculadas com o programa LIFBASE (Luque & Crosley 1999). Nesse poster estão detalhados os procedimentos citados acima, as comparações entre espectros calculados com as novas listas e espectros observados em alta resolução do Sol e de Arcturus, e uma análise do impacto decorrente da utilização de diferentes modelos de atmosfera no espectro sintético. Ao final, temos uma lista de linhas atômicas com mais de 24.000 linhas e uma lista molecular com as moléculas CN, CH, OH, NH, MgH, C2, TiO Gama, CO, FeH, adequadas ao estudo de estrelas G, K e M e populações estelares velhas.

Coelho, P.; Barbuy, B.; Melendez, J.; Allen, D. M.; Castilho, B.

2003-08-01

141

A Tn5051-like mer-containing transposon identified in a heavy metal tolerant strain Achromobacter sp. AO22  

PubMed Central

Background Achromobacter sp. AO22 (formerly Alcaligenes sp. AO22), a bacterial strain isolated from a lead-contaminated industrial site in Australia, was previously found to be resistant to moderate to high levels of mercury, copper and other heavy metals. However, the nature and location of the genetic basis for mercuric ion resistance in this strain, had not been previously identified. Findings Achromobacter sp. AO22 contains a functional mer operon with all four essential genes (merRTPA) and shows >99% DNA sequence identity to that of Tn501. The mer operon was present on a transposon, designated TnAO22, captured by introducing a broad-host-range IncP plasmid into Achromobacter sp. AO22 and subsequently transferring it to E. coli recipients. The transposition frequency of TnAO22 was 10-2 to 10-3 per target plasmid transferred. Analysis of TnAO22 sequence revealed it belonged to the Tn21 subgroup of the Tn3 superfamily of transposons, with the transposition module having >99% identity with Tn5051 of a Pseudomonas putida strain isolated from a water sample in New York. Conclusion TnAO22 is thus a new variant of Tn5051 of the Tn3 superfamily and the transposon and its associated mercury resistance system are among the few such systems reported in a soil bacterium. Achromobacter sp. AO22 can thus be exploited for applications such as in situ mercury bioremediation of contaminated sites, or the mobile unit and mer operon could be mobilized to other bacteria for similar purposes.

Ng, Shee Ping; Davis, Belinda; Palombo, Enzo A; Bhave, Mrinal

2009-01-01

142

Increasing Efficiency at the NTF by Optimizing Model AoA Positioning  

NASA Technical Reports Server (NTRS)

The National Transonic Facility (NTF) at NASA Langley Research Center (LaRC) is a national resource for aeronautical research and development. The government, military and private industries rely on the capability of this facility for realistic flight data. Reducing the operation costs and keeping the NTF affordable is essential for aeronautics research. The NTF is undertaking an effort to reduce the time between data points during a pitch polar. This reduction is being driven by the operating costs of a cryogenic facility. If the time per data point can be reduced, a substantial cost savings can be realized from a reduction in liquid nitrogen (LN2) consumption. It is known that angle-of-attack (AoA) positioning is the longest lead-time item between points. In January 2005 a test was conducted at the NTF to determine the cause of the long lead-time so that an effort could be made to improve efficiency. The AoA signal at the NTF originates from onboard instrumentation then travels through a number of different systems including the signal conditioner, digital voltmeter, and the data system where the AoA angle is calculated. It is then fed into a closed loop control system that sets the model position. Each process along this path adds to the time per data point affecting the efficiency of the data taking process. Due to the nature of the closed loop feed back AoA control and the signal path, it takes approximately 18 seconds to take one pitch pause point with a typical AoA increment. Options are being investigated to reduce the time delay between points by modifying the signal path. These options include: reduced signal filtering, using analog channels instead of a digital volt meter (DVM), re-routing the signal directly to the AoA control computer and implementing new control algorithms. Each of these has potential to reduce the positioning time and together the savings could be significant. These timesaving efforts are essential but must be weighed against possible loss of data quality. For example, a reduction in filtering can introduce noise into the signal and using analog channels could result in some loss of accuracy. Data quality assessments need to be performed concurrently with timesaving techniques since data quality parameters are essential in maintaining facility integrity. This paper will highlight time saving efforts being undertaken or studied at the NTF. It will outline the instrumentation and computer systems involved in setting of the model pitch attitude then suggest changes to the process and discuss how these system changes would effect the time between data points. It also discusses the issue of data quality and how the potential efficiency changes in the system could affect it. Lastly, it will discuss the possibility of using an open loop control system and give some pros and cons of this method.

Crawford, Bradley L.; Spells, Courtney

2006-01-01

143

Determinação de regiões de órbitas diretas estáveis ao redor da Lua  

NASA Astrophysics Data System (ADS)

Neste Trabalho estamos investigando regiões do sistema Terra-Lua que contêm órbitas diretas estáveis ao redor da Lua visando a utilização destas órbitas em futuras missões de veículos espaciais como alternativas de trajetórias com baixo custo de manutenção. Adotando-se o problema restrito de três corpos, Terra-Lua-partícula, a localização e a extensão destas regiões de estabilidade foram investigadas numericamente considerando como estável toda órbita que permanece ao redor a Lua por, no mínimo, 1000 dias com energia de dois corpos da partícula em relação à Lua negativa. A estabilidade de tais regiões está associada a duas famílias de órbitas periódicas simples H1 e H2 e a órbitas quase-periódicas associadas a elas. Uma vez identificadas as regiões de estabilidade passamos a analisá-las introduzindo, paulatinamente, outras interações relevantes ao sistema como as perturbações do Sol (via problema restrito de quatro corpos), das marés, da pressão de radiação e do achatamento terrestre. Os resultados encontrados até o momento mostram que a perturbação do Sol é a única que reduz significativamente o tamanho das regiões de estabilidade. Também estamos investigando o comportamento de tais regiões quando características intrínsecas do sistema como as excentricidades das órbitas da Terra e da Lua e a inclinação da órbita Lua são consideradas. Com este estudo estamos reunindo informações que nos permitirão compreender a evolução das regiões de estabilidade no sistema Terra-Lua, bem como estabelecer parâmetros adequados para a utilização das trajetórias estáveis em futuras missões espaciais. Agradecimentos: Este projeto conta com o apoio do CNPq, da Capes e da Fapesp.

de Melo, C. F.; Winter, O. C.; Vieira Neto, E.

2003-08-01

144

LDEF (Prelaunch), AO187-01 : The Chemistry of Micrometeoroids, Tray A03  

NASA Technical Reports Server (NTRS)

LDEF (Prelaunch), AO187-01 : The Chemistry of Micrometeoroids, Tray A03 The prelaunch photograph shows the two (2) clam shell type canisters in their closed position. The canister shells are made of aluminum sheet material with end caps of diecast aluminum. The baseplate and support structure are fabricated from 6000 series aluminum. Fasteners are non-magnetic stainless steel. The electrical box and the stainless steel tubing located on the baseplate protect the drive system wiring. The experiment contains a timing mechanism that provides the intelligence to open the canisters after the Orbiter has departed the area and any initial outgassing or offgassing has occurred.

1984-01-01

145

The optical periodic analysis of BL Lac object AO 0235+164  

NASA Astrophysics Data System (ADS)

BL Lac object AO 0235+164 is a well-known object. We collect a large number of effective observation in B, V, R and I band from historical literatures. The possible periods are analyzed by means of discrete correlation function (DCF) method, structure function (SF) method and Jurkevich (J-K) method. The results show that there are possible periodic variations of 2.63-2.66 years in B band, 2.79-2.84 years in V band, 2.57-2.87 years in R band, 2.62-2.88 years in I band, respectively.

Wang, Hongtao

2014-05-01

146

VSOP Monitoring of the Compact BL Lac Object AO 0235+164  

NASA Astrophysics Data System (ADS)

In 1999, the highly compact and variable BL Lac object AO 0235+ 164 was identified as the highest brightness temperature active galactic nucleus observed with the VLBI Space Observatory Programme (VSOP), with TB > 5.8 × 1013 K (Frey et al. 2000). The sub-milliarcsec radio structure of this source has been studied with dual-frequency (1.6 and 5GHz), polarization-sensitive VSOP observations during 2001 and 2002. Here we present the results of this monitoring campaign. At the time of these observations, the source was weakly polarized and characterized by a radio core that is clearly resolved on space-ground baselines.

Frey, Sándor; Gurvits, Leonid I.; Gabuzda, Denise C.; Salter, Chris J.; Altschuler, Daniel R.; Perillat, Phil; Aller, Margo F.; Aller, Hugh D.; Hirabayashi, Hisashi; Davis, Michael M.

2006-04-01

147

Imprints of The Northern Mode (NAO/ao) On The Distribution of Col Systems  

NASA Astrophysics Data System (ADS)

The distribution of cu-off low systems (COLs) could be an interesting climate diagno- sis parameter in the dabate about the regional character of North Atlantic Oscillation (NAO) versus the hemisferic character of the Arctic Oscillation (AO). COL systems are usually closed circulations at middle and upper troposphere developed from a deep trough in the westerlies (Palmen and Newton, 1969; Winkler et al., 2000). These sys- tems are largerly influenced by blocking and consequently their number, size, temporal and spatial distribution should be affected by the NAO / AO. This would be a point in favour of the NAO paradigm versus AO paradigm as recognized by Wallace (2000). Cut-off low systems were identified in the band 20zN-70zN using data from the re- analysis NCEP-NCAR for the period from 1958 to 1998. To quantify NAO we use the 41 winter values of NAO index as the normalized pressure difference between Ponta Delgada (Azores) and Reykjavik (Iceland). An automated procedure was developed to identify individual cut-off lows. COL sys- tems were determinated according to the following five steps procedure: 1)Minimum of 200hPa geopotential, 2)Cut-off circulation, 3) Minimum of equivalent thickness, 4) A baroclinic area, 5) Thermodinamic inestability. The areas of most frecuent occurrence(Atlantic Ocean around 20zW-20zE and 37zN- 44zN and in the Pacific area around 120zW-135W and 33z N-41zN) are the same in the two phases of NAO but there are a significant difference: the density of COL systems are higher during NAO positive phase than during NAO negative phase, the density in the negative phase is about the third part of the density in the positive phase. A variability associated to NAO in the frecuency of COL systems centered in both sides of the atlantic area is a clear support for the NAO paradigm vs. AO paradigm.

Nieto, R.; Gimeno, L.; Ribera, P.; Gallego, D.; Garcia, R.; Hernandez, E.; de La Torre, L.

148

Recent Progress in CMOS Integrated Mems AO Mirror Development - Oral Paper  

NASA Astrophysics Data System (ADS)

For high-resolution optical phase control the Fraunhofer IPMS has developed a CMOS-integrated MEMS micro mirror array including 240 × 200 independently deflectable piston mirror elements of 40 ?m pixel size. To further improve the actual mirror performance, amorphous TiAl has been successfully implemented as a novel CMOS-integrable actuator material providing a virtually drift-free deflection. In addition, first two-level designs with separated mirrors and hinges have been realized offering the potential of increased mechanical stroke at improved optical fill factor. Finally, the high wavefront correction capability of the IPMS mirror device has been demonstrated within an AO testbed.

Gehner, A.; Schmidt, J. U.; Wildenhain, M.; Knobbe, J.; Wagner, M.

2008-01-01

149

An overview of the first results on the solar array passive LDEF experiment (sample), AO171  

NASA Technical Reports Server (NTRS)

Space environmental effects were visibly obvious on components of experiment AO171 which contained solar cells, composites, polymeric thin films, solar reflectors, protective coatings, metals, paints , and elastomers. Micrometeoroid/space debris impacts were observed on all experiment elements. Luminescence of polyimide, silicone, and polyurethane materials occurred under black light examination. Outgassing of RTV511 occurred mainly as a result of insufficient thermal vacuum bakeout. Solar cell degradation was predominantly below 10 percent. Elastomers lost mass and discolored; composites showed evidence of atomic oxygen attack, and unprotected thin polymer films eroded away.

Whitaker, Ann F.; Young, Leighton E.

1991-01-01

150

LDEF (Postflight), AO180 : The Effect of Space Environment Exposure on the Properties of Polymer Mat  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO180 : The Effect of Space Environment Exposure on the Properties of Polymer Matrix Composite Materials, Tray D12 The postflight photograph was taken in the SAEF-II facility prior to removal of experiment trays from the LDEF. The Polymer Matrix Composite Materials experiment appears the same as in the flight photograph. The composite containing the aramid (Kevlar) fibers has changed from a yellow to a light brown color and the cylinderical tubes containing the boron and carbon fiber materials have changed from a light green tint to a brown color. The experiment mounting hardware and fasteners seem to be intact and in very good condition.

1990-01-01

151

Tomographic separation of composite spectra - The components of the O-star spectroscopic binary AO Cassiopeiae  

NASA Technical Reports Server (NTRS)

The UV photospheric lines of the short-period, double-lined O-star spectroscopic binary AO Cas are analyzed. Archival data from IUE (16 spectra uniformly distributed in orbital phase) were analyzed with a tomography algorithm to produce the separate spectra of the two stars in six spectral regions. The spectral classifications of the primary and secondary, O9.5 III and O8 V, respectively, were estimated through a comparison of UV line ratios with those in spectral standard stars. An intensity ratio of 0.5-0.7 (primary brighter) at 1600 A is compatible with the data.

Bagnuolo, William G., Jr.; Gies, Douglas R.

1991-01-01

152

Cavitation Performance of a Propeller Design for a Naval Auxiliary Oiler (AO 177) (Model 5326 with Design Propeller 4645).  

National Technical Information Service (NTIS)

Cavitation experiments were performed on a model propeller designed for (AO 177). The results showed satisfactory performance concerning power loss; However, a potential problem with erosion is predicted based on these results. Additional erosion studies ...

K. Remmers N. A. McDonald R. Hecker

1974-01-01

153

The properties and performance of poly AO™-79; A nonabsorbable, polymeric antioxidant intended for use in foods  

Microsoft Academic Search

and Summary  The physical, chemical, and biological characteristics of Poly AO™-79, a composition selected from a class of polymers prepared\\u000a by the polycondensation of divinylbenzene and a blend of various sterically hindered phenols and hydroquinone, are discussed.\\u000a Data are presented indicating that Poly AO™-79 demonstrates excellent antioxidant activity in stabilizing vegetable oils when\\u000a compared to monomeric food grade antioxidants [butylated hydroxytoluene

Thomas E. Furia; Nicolo Bellanca

1977-01-01

154

LDEF (Postflight), AO187-01 : The Chemistry of Micrometeoroids, Tray A03  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO187-01 : The Chemistry of Micrometeoroids, Tray A03 EL-1994-00266 LDEF (Postflight), AO187-01 : The Chemistry of Micrometeoroids, Tray A03 The experiment is shown in the postflight configuration before closing the canisters with ground support equipment that bypassed the experiments onboard electronics circuitry. Three full panels and approximately 3/4th of the other panel are covered with gold foil (>99.99 percent pure). The remaining area on the fourth panel is covered with strips of other detector materials: zirconium, beryllium, titanium, platium, aluminum, carbon, Kapton, polyethylene and TEFLON®. A brown stain is visible on the experiment tray flanges, however, most of the stains observed in the flight photograph are obscured by reflected light. All materials remain intact with no visual evidence of damage to the experiment. The reflection of a video camera on a tripod and light sources can be seen on the gold foil covered panels. The experiment canisters are shown after being closed by using the experiments ground support equipment. The stain buildup can be clearly seen at the vertical center of the right tray flange. The clean area was located under the experiment tray clamp block and was not exposed to the staining medium. The stain also coats other areas that were exposed during the mission but are not as noticeable. The experiment hardware seems to be intact and have no damage.

1990-01-01

155

OCam with CCD220, the Fastest and Most Sensitive Camera to Date for AO Wavefront Sensing  

NASA Astrophysics Data System (ADS)

For the first time, subelectron readout noise has been achieved with a camera dedicated to astronomical wavefront-sensing applications. The OCam system demonstrated this performance at a 1300 Hz frame rate and with 240 × 240 pixel frame size. ESO and JRA2 OPTICON jointly funded e2v Technologies to develop a custom CCD for adaptive optics (AO) wavefront-sensing applications. The device, called CCD220, is a compact Peltier-cooled 240 × 240 pixel frame-transfer eight-output back-illuminated sensor using the EMCCD technology. This article demonstrates, for the first time, subelectron readout noise at frame rates from 25 Hz to 1300 Hz and dark current lower than 0.01 e- pixel-1 frame-1 . It reports on the quantitative performance characterization of OCam and the CCD220, including readout noise, dark current, multiplication gain, quantum efficiency, and charge transfer efficiency. OCam includes a low-noise preamplifier stage, a digital board to generate the clocks, and a microcontroller. The data acquisition system includes a user-friendly timer file editor to generate any type of clocking scheme. A second version of OCam, called OCam2 , has been designed to offer enhanced performance, a completely sealed camera package, and an additional Peltier stage to facilitate operation on a telescope or environmentally challenging applications. New features of OCam2 are presented in this article. This instrumental development will strongly impact the performance of the most advanced AO systems to come.

Feautrier, Philippe; Gach, Jean-Luc; Balard, Philippe; Guillaume, Christian; Downing, Mark; Hubin, Norbert; Stadler, Eric; Magnard, Yves; Skegg, Michael; Robbins, Mark; Denney, Sandy; Suske, Wolfgang; Jorden, Paul; Wheeler, Patrick; Pool, Peter; Bell, Ray; Burt, David; Davies, Ian; Reyes, Javier; Meyer, Manfred; Baade, Dietrich; Kasper, Markus; Arsenault, Robin; Fusco, Thierry; Diaz Garcia, José Javier

2011-03-01

156

Study of isoplanatic angle of dual-conjugate AO system in atmospheric turbulence  

NASA Astrophysics Data System (ADS)

The limitation of classical AO and the basic principle of MCAO are briefly introduced. A dual-conjugate AO (tow-DM MCAO) can offer a possibility of widening FOV characterized by the isoplanatic angle, Considering the application of lidar, the isoplanatic angle's expressions of MCAO for uplink and downlink are deduced in this paper. And through simulation, the conjugate height, the isoplanatic angle, the isoplanatic angle gain and the coherence length for dual-conjugate system are thoughtfully discussed. The results show the conjugate heights play a great role in widening the isoplanatic angle, and the isoplanatic angle retains maximum when the conjugate heights is at optimal altitudes. For the ground lidar, the positions of optimal conjugate heights simulated are about 1 and 12 km, and the optimal detecting height is 17 km. For the air-borne lidar, the isoplanatic angle gain is minimum at the height of 13 km, and fails to reach an optimal detecting state, and the selection of the optimal conjugate height is relative with not only the coherence length but also the height of air-borne system.

Ding, Xueke; Rong, Jian; Zhong, Xiaochun; Li, Fang

2007-11-01

157

LDEF (Postflight), AO015 : Free-Flyer Biostack Experiment, Tray G02  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO015 : Free-Flyer Biostack Experiment, Tray G02 The post flight photograph was taken in the SAEF II at KSC after the experiment tray was removed from the LDEF. The experiment tray flanges and sidewalls have become discolored with a light tan stain except where the tray clamp blocks were located. The Biostack experiment appears to have survived the extended mission with no visible damage. The experiment housings are intact and all hardware is securely in place. The detector housings appear to be discolored with a stain similar to that on the tray hardware. The exposed Kapton H foil covering windows in two (2) detector housings do not appear to have sustained damage dur ing the extended mission. The perforated dome on two (2) of the detector housings has a slight tan discoloration but no indication of damage.

1990-01-01

158

LDEF (Postflight), AO139A : Growth of Crystals From Solutions in Low Gravity, Tray G06  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO139A : Growth of Crystals From Solutions in Low Gravity, Tray G06 The postflight photograph was taken in the SAEF II at KSC after the experiment tray was removed from the LDEF. The experiment tray flanges have become discolored with a light tan stain except where the tray clamp blocks were located. A darker stain appears to exist at the intersection of the white cover plate and the upper left flange of the experiment tray. The Crystal Growth experiment appears to have survived the extended mission with no visible damage. The experiment cover plate, originally white, appears to be discolored by a very light brown stain but is intact and securely in place.

1990-01-01

159

[First experiences with unreamed AO intramedullary nail in treatment of femoral shaft fractures].  

PubMed

The unreamed femoral nail (UFN) system, with its numerous proximal interlocking options, allows a minimal invasive surgical procedure for the treatment of nearly all femoral fracture patterns. Sixty-six fractures, 5 cases of osteolysis or pathologic fractures, 2 limb shortenings and 1 lengthening (monorail technique) and 3 cases of pseudarthrosis were stabilised with the UFN from July 1994 to December 1996. The fractures were analysed according to the AO classification. We found 31 polytrauma patients with an mean ISS of 21.8 and a mean PTS of 25.4. Most of the multiply injured patients (n = 26) were stabilised with the UFN primarily. Follow-up of 44 patients ranged from 4 to 18 months postoperatively. According to our clinical and radiological score the results were excellent in 34% of cases, good in 36.3%, poor in 20.4% and bad in 9%. Average fracture healing time was about 9.8 weeks. PMID:9340239

Stockenhuber, N; Hofer, H P; Schweighofer, F; Bratschitsch, G; Szyszkowitz, R

1997-07-01

160

Functional expression of amine oxidase from Aspergillus niger (AO-I) in Saccharomyces cerevisiae.  

PubMed

The aim of this work was to prepare recombinant amine oxidase from Aspergillus niger after overexpressing in yeast. The yeast expression vector pDR197 that includes a constitutive PMA1 promoter was used for the expression in Saccharomyces cerevisiae. Recombinant amine oxidase was extracted from the growth medium of the yeast, purified to homogeneity and identified by activity assay and MALDI-TOF peptide mass fingerprinting. Similarity search in the newly published A. niger genome identified six genes coding for copper amine oxidase, two of them corresponding to the previously described enzymes AO-I a methylamine oxidase and three other genes coding for FAD amine oxidases. Thus, A. niger possesses an enormous metabolic gear to grow on amine compounds and thus support its saprophytic lifestyle. PMID:17899443

Kolaríková, Katerina; Galuszka, Petr; Sedlárová, Iva; Sebela, Marek; Frébort, Ivo

2009-01-01

161

Villages: an on-sky visible wavelength astronomy AO experiment using a MEMS deformable mirror  

NASA Astrophysics Data System (ADS)

The MEMS-AO/Villages project consists of a series of on-sky experiments that will demonstrate key new technologies for the next generation of adaptive optics systems for large telescopes. One of our first goals is to demonstrate the use of a micro-electro-mechanical systems (MEMS) deformable mirror as the wavefront correcting element. The system is mounted the 1-meter Nickel Telescope at the UCO/Lick Observatory on Mount Hamilton. It uses a 140 element (10 subapertures across) MEMS deformable mirror and is designed to produce diffraction-limited images at wavelengths from 0.5 to 1.0 microns. The system had first light on the telescope in October 2007. Here we report on the results of initial on-sky tests.

Gavel, Donald; Severson, Scott; Bauman, Brian; Dillon, Daren; Reinig, Marco; Lockwood, Christopher; Palmer, Dave; Morzinski, Kathleen; Ammons, Mark; Gates, Elinor; Grigsby, Bryant

2008-03-01

162

Analysis of Optical Variations of BL Lac Object AO 0235+164  

NASA Astrophysics Data System (ADS)

Historical optical BVRI band data are combined on the BL Lac object AO 0235 + 164. In order to examine the possible existence of lags and correlations between variations in different optical bands from this source, a statistical analysis is performed through the Discrete Correlation Function (DCF) method. Monte Carlo simulations called Flux Redistribution/Random Subset Selection (FR/RSS) are performed to obtain statistically meaningful values for the cross-correlation time lags and their related uncertainties. The analysis confirms that the variations in different optical light curves are strongly correlated, with no or very weak lag within the errors. Long term variability of color indices are also analysed. No color variabilities are found.

Hong-tao, Wang

2014-03-01

163

LDEF (Flight), AO015 : Free-Flyer Biostack Experiment, Tray G02  

NASA Technical Reports Server (NTRS)

LDEF (Flight), AO015 : Free-Flyer Biostack Experiment, Tray G02 The flight photograph was taken from the Orbiter aft flight deck during the LDEF retrieval. The paint dots on the experiment tray clamp blocks, originally white, have become discolored. The LDEF end frame structure also is discolored in locations adjacent to the edge of the black thermal panels. The Biostack experiment appears to have survived the extended mission with no visible damage. The experiment housings are intact and all hardware is securely in place. The exposed Kapton H foil covering windows in two (2) detector housings are deformed due to a positive internal pres sure but do not appear to have sustained damage. The Kapton H foil covers are visible beneath the perforated dome on two (2) of the detector housings with no indication of damage.

1990-01-01

164

High contrast experiment of an AO-free coronagraph with a checkerboard pupil mask  

NASA Astrophysics Data System (ADS)

Context: A high contrast coronagraph is expected to provide one of the promising ways to directly observe extra-solar planets. We present the newest results of our laboratory experiment investigating “rigid” coronagraph with a binary shaped checkerboard pupil mask, which should offer a highly stable solution for telescopes without adaptive optics (AO) for wavefront correction in space missions. Aims: The primary aim of this work was to study the stability of the coronagraph, and to demonstrate its performance without adaptive wavefront correction. Estimation of both the raw contrast and the gain of the point spread function (PSF) subtraction were needed. The limiting factor of the contrast was also important. Methods: A binary shaped pupil mask of a checkerboard type has been designed. The mask, consisting of an aluminum film on a glass substrate, was manufactured using nano-fabrication techniques with electron beam lithography. Careful evaluation of coronagraphic performance, including PSF subtraction, was carried out in air using the developed mask. Results: A contrast of 6.7 × 10-8 was achieved for the raw coronagraphic image by areal averaging of all of the observed dark regions. Following PSF subtraction, the contrast reached 6.8 × 10-9. Speckles were a major limiting factor throughout the dark regions of both the raw image and the PSF subtracted image. Conclusions: A rigid coronagraph with PSF subtraction without AO is a useful method to achieve high contrast observations. Applications of a rigid coronagraph to a Space Infrared telescope for Cosmology and Astrophysics (SPICA) and other platforms are discussed.

Enya, K.; Abe, L.; Tanaka, S.; Nakagawa, T.; Haze, K.; Sato, T.; Wakayama, T.

2008-03-01

165

Aspergillus oryzae AoSO Is a Novel Component of Stress Granules upon Heat Stress in Filamentous Fungi  

PubMed Central

Stress granules are a type of cytoplasmic messenger ribonucleoprotein (mRNP) granule formed in response to the inhibition of translation initiation, which typically occurs when cells are exposed to stress. Stress granules are conserved in eukaryotes; however, in filamentous fungi, including Aspergillus oryzae, stress granules have not yet been defined. For this reason, here we investigated the formation and localization of stress granules in A. oryzae cells exposed to various stresses using an EGFP fusion protein of AoPab1, a homolog of Saccharomyces cerevisiae Pab1p, as a stress granule marker. Localization analysis showed that AoPab1 was evenly distributed throughout the cytoplasm under normal growth conditions, and accumulated as cytoplasmic foci mainly at the hyphal tip in response to stress. AoSO, a homolog of Neurospora crassa SO, which is necessary for hyphal fusion, colocalized with stress granules in cells exposed to heat stress. The formation of cytoplasmic foci of AoSO was blocked by treatment with cycloheximide, a known inhibitor of stress granule formation. Deletion of the Aoso gene had effects on the formation and localization of stress granules in response to heat stress. Our results suggest that AoSO is a novel component of stress granules specific to filamentous fungi. The authors would specially like to thank Hiroyuki Nakano and Kei Saeki for generously providing experimental and insightful opinions.

Huang, Hsiang-Ting; Maruyama, Jun-ichi; Kitamoto, Katsuhiko

2013-01-01

166

Possible impact of the autumnal North Pacific SST and November AO on the East Asian winter temperature  

NASA Astrophysics Data System (ADS)

This study investigates the effects of the North Pacific sea surface temperature (NP SST) anomalies on the East Asian winter temperature (TEA), and the relationship between the Arctic Oscillation (AO) and NP SST anomalies in association with TEA. Time-lagged correlation analysis revealed that the third mode of the September-October-November (SON) mean NP SST ("SON SST 3rd mode") and the AO index for November ("Nov AO") are closely related to TEA, and further that the first and second modes of NP SST are associated with the Pacific Decadal Oscillation (PDO) and Pacific North America (PNA) patterns, respectively. This study reveals that when the SON SST 3rd mode and Nov AO have a positive (negative) phase, the intensity of the Siberian High weakens (strengthens), which in turn weakens (strengthens) the East Asian winter monsoon (EAWM), resulting in a warm (cold) winter in East Asia. Our results suggest that the North Pacific Ocean signals influence the AO, which is one of the most pronounced Northern Hemispheric atmospheric global patterns. Such an influence in turn governs the continental-scale circulation over Siberia and affects the subsequent local climate variation over the East Asia regions.

Kim, Hae-Jeong; Ahn, Joong-Bae

2012-06-01

167

The Magellan Adaptive Secondary VisAO Camera: diffraction-limited broadband visible imaging and 20mas fiber array IFU  

NASA Astrophysics Data System (ADS)

The Magellan Adaptive Secondary AO system, scheduled for first light in the fall of 2011, will be able to simultaneously perform diffraction limited AO science in both the mid-IR, using the BLINC/MIRAC4 10?m camera, and in the visible using our novel VisAO camera. The VisAO camera will be able to operate as either an imager, using a CCD47 with 8.5 mas pixels, or as an IFS, using a custom fiber array at the focal plane with 20 mas elements in its highest resolution mode. In imaging mode, the VisAO camera will have a full suite of filters, coronagraphic focal plane occulting spots, and SDI prism/filters. The imaging mode should provide ~20% mean Strehl diffraction-limited images over the band 0.5-1.0 ?m. In IFS mode, the VisAO instrument will provide R~1,800 spectra over the band 0.6-1.05 ?m. Our unprecedented 20 mas spatially resolved visible spectra would be the highest spatial resolution achieved to date, either from the ground or in space. We also present lab results from our recently fabricated advanced triplet Atmospheric Dispersion Corrector (ADC) and the design of our novel wide-field acquisition and active optics lens. The advanced ADC is designed to perform 58% better than conventional doublet ADCs and is one of the enabling technologies that will allow us to achieve broadband (0.5-1.0?m) diffraction limited imaging and wavefront sensing in the visible.

Kopon, Derek; Close, Laird M.; Males, Jared; Gasho, Victor; Follette, Katherine

2010-07-01

168

Comparative analysis of the main bioactive components of San-ao decoction and its series of formulations.  

PubMed

A high performance liquid chromatographic (HPLC) method with diode array detection (DAD) was established for simultaneous determination of seven main bioactive components in San-ao decoction and its series of formulae (San-ao decoction, Wu-ao decoction, Qi-ao decoction and Jia-wei San-ao decoction). Seven compounds were analyzed simultaneously with a XTerra C(18) column (4.6 mm × 250 mm, 5 µm) using a linear gradient elution of a mobile phase containing acetonitrile (A) and a buffer solution (0.02 mol/L potassium dihydrogen phosphate and adjusted to pH 3 using phosphoric acid) (B); the flow rate was 1.0 mL/min. The sample was detected with DAD at 210, 254 and 360 nm and the column was maintained at 30 °C. All the compounds showed good linearity (r2 > 0.9984) in the tested concentration range. The precisions were evaluated by intra-day and inter-day tests, and relative standard deviation (R.S.D.) values within the range of 0.83%–2.53% and 0.64%–2.77% were reported, respectively. The recoveries of the quantified compounds were observed to cover a range from 95.34% and 104.82% with R.S.D. values less than 2.72%. The validated method was successfully applied for the simultaneous determination of seven main bioactive components including ephedrine (1), amygdalin (2), liquiritin (3), benzoic acid (4), isoliquiritin (5), formononetin (6) and glycyrrhizic acid (7) in San-ao decoction and its series of formulae. The results also showed a wide variation in the content of the identified active compounds in these samples, which could also be helpful to illustrate the drug interactions after some herbs combined in different formulations. PMID:23117432

Shu, Xiaoyun; Tang, Yuping; Jiang, Chenxue; Shang, Erxing; Fan, Xinshen; Ding, Anwei

2012-01-01

169

A roadmap for a new era turbulence studies program applied to the ground-based astronomy supported by AO  

NASA Astrophysics Data System (ADS)

Sites selection for ELTSs concluded and a new era opens for turbulence studies in application to the ground-based astronomy supported by AO. If in the last decade the main interest of astronomy has been focused on the characterization of sites, now priorities change. In the last years more and more AO systems have seen their first light. A few more complex AO techniques are still in a phase of verification/validation. The efficiency of the operating and forthcoming AO systems can strongly be affected by turbulence and observation strategies rely on our ability in knowing in advance the turbulence spatial distribution in a region around the telescope. Progresses in development of more sophisticated AO techniques (such as the LTAO, MCAO and MOAO) definitely depend on a more detailed knowledge of the main turbulence features such as the turbulence stratification at high vertical resolution. An European working group has been recently set-up aiming at defining the roadmap of a program of site testing campaigns for OT measurements having multiple goals mainly addressed to support requirements for 3D OT modeling with hydrodynamical approach and AO at wide field in application to the ground-based astronomy. The main first objective of this program will be the absolute instrument cross-calibration (in particular the vertical profilers for the whole troposphere and low stratosphere ~20km) and validation of techniques for turbulence stratification on the same vertical range at high vertical resolution (with the optimal goal of 100-200m). In this contribution we will present the motivations of our work, the goals, the instrumentation we are taking into accounts, the different strategies and constraints we are considering for the conception of site testing campaigns.

Masciadri, Elena; Rousset, Gérard; Fusco, Thierry; Basden, Alastair; Bonifacio, Piercarlo; Fuensalida, Jesus; Robert, Clélia; Sarazin, Marc; Wilson, Richard; Ziad, Aziz

2013-12-01

170

LDEF (Postflight), AO171 : Solar-Array-Materials Passive LDEF Experiment, Tray A08  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO171 : Solar-Array-Materials Passive LDEF Experiment, Tray A08 EL-1994-00147 LDEF (Postflight), AO171 : Solar-Array-Materials Passive LDEF Experiment, Tray A08 The post flight photograph was taken in the SAEF II at KSC prior to removal of the experiment tray from the LDEF and shows the Solar Array Materials Passive LDEF Experiment (SAMPLE) on the LDEF. Six (6) plates of passive components, provided by various experiment organizations and designated plate I thru plate VI, are shown mounted in a three (3) inch deep LDEF peripheral tray. All six plates are aluminum and attach to the LDEF experiment tray with non-magnetic stainless steel fasteners. Plate I, located in the upper right corner, consist of a combination of solar cells with and without covers, solar cell modules and solar arrays assembled on the baseplate. Three of the four solar arrays are missing. Other components appear to be secure. Plate II in the top center section, has twenty seven (27) composite samples, carbon fiber and glass fiber, mounted on the baseplate. The composites appear to be intact with no physical damage. Plate III, in the upper left corner, consist of metallized and thin polymeric films (Kapton, Mylar, TEFLON® , white Tedlar,etc.). The thin films without protective coatings sustained significant damage and most were destroyed. The thin film specimen hanging by one end in the flight photograph is missing. The metallized film apparently survived the mission with minimum damage. Plate IV located in the lower right corner consist of metals and coatings mounted in an aluminum baseplate and covered with a thin aluminum coverplate that partially mask the specimen. Several of the coatings appear to have darkened and a unique pattern of light brown discoloration appears around the outer edges of the mounting plate and along the lower edge of the coverplates. Plate V, in the lower center section, contained thermal plastics and structural film configured into tensile and shear specimen. All specimen, including the tape holding down the small specimen in the lower right corner, have darkened significantly during the extended time in space. Plate VI, in the lower left corner, is populated with solar cells and associated components such as covers, encapsulants,adhesives, etc. The solar cell components appear to be intact with no apparent physical damage.The colors of the specimen, however, appear to have darkened. The photographic lighting angle has significantly highlighted abrasions on the mounting plate surface.

1990-01-01

171

LDEF (Flight), AO171 : Solar-Array-Materials Passive LDEF Experiment, Tray A08  

NASA Technical Reports Server (NTRS)

LDEF (Flight), AO171 : Solar-Array-Materials Passive LDEF Experiment, Tray A08 EL-1994-00666 LDEF (Flight), AO171 : Solar-Array-Materials Passive LDEF Experiment, Tray A08 The flight photograph was taken from the Orbiter aft flight deck during the LDEF retrieval prior to berthing the LDEF in the Orbiter cargo bay and shows the Solar Array Materials Passive LDEF Experiment (SAMPLE) on the LDEF. Six (6) plates of passive components, provided by various experiment organizations and designated plate I thru plate VI, are shown mounted in a three (3) inch deep LDEF peripheral tray. All six plates are aluminum and attach to the LDEF experiment tray with non-magnetic stainless steel fasteners. Plate I, located in the upper left corner, consist of a combination of solar cells with and without covers, solar cell modules and solar arrays assembled on the baseplate. Two of the four solar arrays are missing and one appears to be attached at only one corner. Other components appear to be secure. Plate II in the left center section, has twenty-seven (27) composite samples, carbon fiber and glass fiber, mounted on the baseplate. The composites appear to be intact with no physical damage. Plate III, in the lower left corner, consist mostly of metallized and thin polymeric films (Kapton, Mylar, TEFLON® , white Tedlar,etc.). The thin films without protective coatings sustained significant damage and most were destroyed. The metallized film apparently survived with minimum damage. Plate IV located in the upper right corner consist of metals and coatings mounted in an aluminum baseplate and covered with a thin aluminum coverplate that partially mask the specimen. Several of the coatings appear to have changed to a darker color and a light brown discoloration appears around the outer edges of the mounting plate and along the right edge of the coverplates. Plate V, in the right center section, contained thermal plastics and structural film configured into tensile and shear specimen. All specimens, including the tape holding down the small specimen in the lower right corner, have darkened significantly during the extended time in space. Plate VI, in the lower right corner, is populated with solar cells and associated components such as covers, encapsulants,adhesives, etc.. The solar cell components appear to be intact with no apparent physical damage.The colors of the specimen, however, appear to have darkened.

1990-01-01

172

The AOLI Non-Linear Curvature Wavefront Sensor: High sensitivity reconstruction for low-order AO  

NASA Astrophysics Data System (ADS)

Many adaptive optics (AO) systems in use today require bright reference objects to determine the effects of atmospheric distortions on incoming wavefronts. This requirement is because Shack Hartmann wavefront sensors (SHWFS) distribute incoming light from reference objects into a large number of sub-apertures. Bright natural reference objects occur infrequently across the sky leading to the use of laser guide stars which add complexity to wavefront measurement systems. The non-linear curvature wavefront sensor as described by Guyon et al. has been shown to offer a significant increase in sensitivity when compared to a SHWFS. This facilitates much greater sky coverage using natural guide stars alone. This paper describes the current status of the non-linear curvature wavefront sensor being developed as part of an adaptive optics system for the Adaptive Optics Lucky Imager (AOLI) project. The sensor comprises two photon-counting EMCCD detectors from E2V Technologies, recording intensity at four near-pupil planes. These images are used with a reconstruction algorithm to determine the phase correction to be applied by an ALPAO 241-element deformable mirror. The overall system is intended to provide low-order correction for a Lucky Imaging based multi CCD imaging camera. We present the current optical design of the instrument including methods to minimise inherent optical effects, principally chromaticity. Wavefront reconstruction methods are discussed and strategies for their optimisation to run at the required real-time speeds are introduced. Finally, we discuss laboratory work with a demonstrator setup of the system.

Crass, Jonathan; King, David; Mackay, Craig

2013-12-01

173

Ruled and holographic experiment (AO 138-5). [long duration exposure facility  

NASA Technical Reports Server (NTRS)

The AO 138-5 experiment has been designed, via the French Cooperative Payload (FRECOPA) experiment with the aim to study the optical behavior of different diffraction gratings submitted to space vacuum long exposure and solar radiation. Samples were rules and holographic gratings, masters or replica, and some additional control mirrors with various coatings. The experiment was located on the B3, trailing edge of the Long Duration Exposure Facility (LDEF) and has been protected against atomic oxygen flux. The experienced thermal cycling has been evaluated from -23 C to 66 C during the flight, 34,000 orbits. The analysis has been focused on the triple point characterization including light efficiency, wavefront flatness quality and stray light level. Tests were conducted on control mirrors and gratings loaded but not exposed to cosmic dust or solar irradiations. They did not show any significant variations. Solar exposure has damaged the coating reflectivity in the ultraviolet region, the degradation is higher with the gratings, in terms of efficiency. However, wavefront flatness quality and stray light level tests revealed no additional changes.

Bonnemason, Francis

1992-01-01

174

Wide Tertiary Companions to Nearby Spectroscopic Binaries: A Close Look with Gemini-North AO  

NASA Astrophysics Data System (ADS)

We report on the preliminary findings of a multi-epoch, common proper motion (CPM) search for tertiary companions to known, nearby spectroscopic binary systems. Simulations of the star forming environment indicate that, in order to produce the very small separations of such systems, a third member can carry away angular momentum, tightening the binary. This third member typically has a low-mass and remains bound to the system. We use NIRI-Altair AO imaging on Gemini-North to search for close tertiary companions to a sample of 91 spectroscopic binaries. We collect the data in two narrow-band filters separated by approximately one year. The two filters are centered just outside of the 1.6 ?m methane feature (CH4short) and just inside it (CH4long). This allows for two forms of candidate identification: 1) CPM and 2) methane dropout if the object is a T dwarf. At this time, we have obtained and analyzed 60 multi-epoch fields. We confirm a previously known CPM companion and identify three sub-stellar candidates and two M dwarf candidates.

Allen, P. R.; Close, L.

2011-12-01

175

LDEF (Prelaunch), AO015 : Free-Flyer Biostack Experiment, Tray G02  

NASA Technical Reports Server (NTRS)

LDEF (Prelaunch), AO015 : Free-Flyer Biostack Experiment, Tray G02 The prelaunch photograph shows the Bio stack experiment containers mounted on a baseplate and installed in a six (6) inch deep LDEF end corner experiment tray. Non-magnetic stainless steel fasteners were used in all mechanical joint assemblies. The Biostack experiment consist of twenty (20) detector units in hermetically sealed aluminum housings mounted on aluminum baseplates. Eight (8) detector units are mounted on a baseplate and installed in a six (6) inch peripheral tray adjacent to the LDEF trailing edge and twelve (12) detector units mounted on a baseplate are located in the tray shown and will be installed on the earth facing end of the LDEF. The experiment housings and the mounting plate have a thin chro mic anodize surface coating to meet thermal requirements. Two (2) housings have windows cov ered with Kapton H foil that provides a light filter with low radiation absorption. Two (2) additional housings have windows covered with Kapton H foil but also have perforated aluminum domes to limit incoming earth albedo.

1984-01-01

176

GRAVITY: The AO-Assisted, Two-Object Beam-Combiner Instrument for the VLTI  

NASA Astrophysics Data System (ADS)

We present the proposal for the infrared adaptive optics (AO) assisted, two-object, high-throughput, multiple-beam-combiner GRAVITY for the VLTI. This instrument will be optimized for phase-referenced interferometric imaging and narrow-angle astrometry of faint, red objects. Following the scientific drivers, we analyze the VLTI infrastructure, and subsequently derive the requirements and concept for the optimum instrument. The analysis can be summarized with the need for highest sensitivity, phase referenced imaging and astrometry of two objects in the VLTI beam, and infrared wavefront-sensing. Consequently our proposed instrument allows the observations of faint, red objects with its internal infrared wavefront sensor, pushes the optical throughput by restricting observations to K-band at low and medium spectral resolution, and is fully enclosed in a cryostat for optimum background suppression and stability. Our instrument will thus increase the sensitivity of the VLTI significantly beyond the present capabilities. With its two fibers per telescope beam, GRAVITY will not only allow the simultaneous observations of two objects, but will also push the astrometric accuracy for UTs to 10 ?as, and provide simultaneous astrometry for up to six baselines.

Eisenhauer, F.; Perrin, G.; Rabien, S.; Eckart, A.; Léna, P.; Genzel, R.; Abuter, R.; Paumard, T.; Brandner, W.

177

GRAVITY: The AO assisted, two object beam combiner instrument for the VLTI.  

NASA Astrophysics Data System (ADS)

We present the proposal for the infrared adaptive optics (AO) assisted, two-object, high-throughput, multiple-beam-combiner GRAVITY for the VLTI. This instrument will be optimized for phase-referenced interferometric imaging and narrow-angle astrometry of faint, red objects. Following the scientific drivers, we analyze the VLTI infrastructure, and subsequently derive the requirements and concept for the optimum instrument. The analysis can be summarized with the need for highest sensitivity, phase referenced imaging and astrometry of two objects in the VLTI beam, and infrared wavefront-sensing. Consequently our proposed instrument allows the observations of faint, red objects with its internal infrared wavefront sensor, pushes the optical throughput by restricting observations to K-band at low and medium spectral resolution, and is fully enclosed in a cryostat for optimum background suppression and stability. Our instrument will thus increase the sensitivity of the VLTI significantly beyond the present capabilities. With its two fibers per telescope beam, GRAVITY will not only allow the simultaneous observations of two objects, but will also push the astrometric accuracy for UTs to 10 micro-arcsec, and provide simultaneous astrometry for up to six baselines.

Eisenhauer, F.; Perrin, G.; Rabien, S.; Eckart, A.; Lena, P.; Genzel, R.; Abuter, R.; Paumard, T.

2005-08-01

178

Estimating the reduction of vibrations in MACAO and ALTAIR AO systems using H2 control synthesis  

NASA Astrophysics Data System (ADS)

Vibrations and external disturbances of various origins (e.g. structural, wind, axis control) have been shown to degrade the image quality at the instrument focus of the telescopes. Furthermore, the next generation of extremely large telescopes (ELTs) and their associated adaptive optics (AO) systems will reach new levels of high angular resolution, thus reducing vibrations represents becomes highly desirable to ensure that the scientific instruments will take full advantage of this unprecedented resolution. We present a method that aims to mitigate the effect of vibrations at Paranal's MACAO and Gemini North's ALTAIR instruments. A frequency-based controller, based on the H2 synthesis technique [1,2], is used to maximize the performance of the tip and tilt closed-loop systems. The pseudo open-loop slopes are reconstructed from on-sky data and then used to find the controller that minimizes the variance of the tip-tilt residuals in an off-line simulation of the closed-loop system.

Guesalaga, Andrés; Haguenauer, Pierre; Gonte, Frederic; O'Neal, Jared; Neichel, Benoit; Lai, Olivier Lai; Trujillo, Chad; Guzman, Dani

2013-12-01

179

Detectability of Planets in Wide Binaries by Ground-Based Relative Astrometry with AO  

NASA Astrophysics Data System (ADS)

We observed the 3 arc sec wide visual binary star HD 19994 twice with the VLT NACO AO instrument to measure the separation between the two stars with very high precision, in order to detect the astrometric wobble of star A due to its radial velocity planet Ab, to be measured as periodic change in the binary separation. We obtained roughly 100 short exposure images per epoch and could thereby obtain a relative astrometric precision in measuring the binary separation of below 100 micro arc sec. This is the best precision ever reached in ground-based single- aperture relative astrometry, comparable to a similar program with the HST FGS by Benedict et al. With this precision, it is possible to detect the astrometric wobble (or its upper limit) of star A due to its radial velocity planet as periodic change in the binary separation, to be observed in the next few years. With such a measurement, one can determine the mass of the spectroscopic companion, which is a planet candidate from radial velocity observations (m sin i, unknown orbit inclination i). Once such a project is shown to be successful for a known planet, one can start searching for new planets in binary stars. Such observations are also very useful for significantly improving the orbit of this and many other binaries.

Neuhäuser, R.; Seifahrt, A.; Röll, T.; Bedalov, A.; Mugrauer, M.

2007-08-01

180

The AO\\/ASIF-proximal femoral nail (PFN): a new device for the treatment of unstable proximal femoral fractures  

Microsoft Academic Search

Currently available intramedullary devices for the treatment of unstable pertrochanteric femoral fractures are technically demanding and show a considerable failure rate due to their massiveness and the persistent rotational instability of the head–neck fragment. The Arbeitsgemeinschaft für Osteosynthesefragen (AO\\/ASIF) therefore designed a new intramedullary device, the proximal femoral nail (PFN), which during a handling study was tested in 4 European

R. K. J Simmermacher; A. M Bosch; Chr Van der Werken

1999-01-01

181

Liquid freshwater transport and Polar Surface Water characteristics in the East Greenland Current during the AO02 Oden expedition  

Microsoft Academic Search

Dynamical features of the East Greenland Current (EGC) are synthesized from a survey conducted by the Swedish icebreaker Oden during the International Arctic Ocean – 02 expedition (AO-02) in May 2002 with emphasis on the liquid freshwater transport and Polar Surface Water. The data include hydrography and lowered acoustic doppler current profiler (LADCP) velocities in eight transects along the EGC,

Johan Nilsson; Göran Björk; Bert Rudels; Peter Winsor; Daniel Torres

2008-01-01

182

In-situ characterization of microbial community in an A/O submerged membrane bioreactor with nitrogen removal.  

PubMed

The bacterial community involved in removing nitrogen from sewage and their preferred DO environment within an anoxic/oxic membrane bioreactor (A/O MBR) was investigated. A continuously operated laboratory-scale A/O MBR was maintained for 360 d. At a sludge age of 150 d and a C/N ratio of 3.5, the system was capable of removing 88% of the influent nitrogen from raw wastewater through typical nitrogen removal transformations (i.e. aerobic ammonia oxidation and anoxic nitrate reduction). Characterization of the A/O MBR bacterial community was carried out using fluorescence in situ hybridization (FISH) techniques. FISH results further showed that Nitrosospira spp. and Nitrospira spp. were the predominant groups of ammonia and nitrite oxidizing group, respectively. They constituted up to 11% and 6% of eubacteria at DO below 0.05 mg/l (low DO), respectively, and about 14% and 9% of eubacteria at DO between 2-5 mg/l (sufficient DO), respectively, indicating preference of nitrifiers for a higher DO environment. Generally low counts of the genus Paracoccus were detected while negative results were observed for Paracoccus denitrificans, Alcaligenes spp, and Pseudomonas stutzeri under the low and sufficient DO environments. The overall results indicate that Nitrosospira spp., Nitrospira spp. and members of Paracoccus spp. can be metabolically functional in nitrogen removal in the laboratory-scale A/O MBR system. PMID:15566185

Sofia, A; Liu, W T; Ong, S L; Ng, W J

2004-01-01

183

AoSO protein accumulates at the septal pore in response to various stresses in the filamentous fungus Aspergillus oryzae.  

PubMed

Filamentous ascomycetes form hyphal networks that are compartmentalized by septa which have a perforated pore allowing the passage of cytoplasm and organelles between adjacent hyphal compartments. Thus, the septal pore may play an important role in the organized growth of multicellular organisms. Upon hyphal injury, the septal pore is plugged by a wound-healing organelle, known as the Woronin body, to prevent excessive cytoplasmic leakage. However, the movement of proteins towards the septal pore in response to stress has not been extensively studied in filamentous fungi. In this study, we identified an Aspergillus oryzae protein, AoSO, which is homologous to the Neurospora crassa SO protein that was reported to accumulate at the septal pore in aging hyphae. The DeltaAoso strain showed excessive cytoplasmic leakage upon hyphal injury similar to the Woronin body-deficient strain DeltaAohex1. Cellular localization studies using EGFP showed that AoSO accumulated at the septal pore adjacent to the injured compartment, while it was dispersed throughout the cytoplasm under normal growth conditions. These results indicate that AoSO plays a role in preventing excessive cytoplasmic leakage upon hyphal injury by accumulating at the septal pore. Furthermore, AoSO accumulated at the septal pore in response to various stresses, including low and high temperature, extreme acidic and alkaline pH, and nitrogen and carbon depletion. Physical stress induced by pulse laser treatment on a hyphal region at a distance from the septum caused accumulation of the AoSO protein at the septal pore within only a few minutes. This study presents a novel behavior in which a filamentous fungal protein relocalizes to the septal pore in response to various stresses. PMID:19945422

Maruyama, Jun-ichi; Escaño, Cristopher Salazar; Kitamoto, Katsuhiko

2010-01-01

184

Orbital Period Changes and Their Evolutionary Status for the Weak-Contact Binaries. III. AO Camelopardalis and AH Tauri  

NASA Astrophysics Data System (ADS)

In this paper, we presented multicolor photometric observations for two eclipsing binaries, AO Camelopardalis and AH Tauri, obtained on 2008 December 16 and 17. Using the Wilson-Devinney Code, the photometric solution of AH Tau was determined from our new CCD data. The mass ratio and the fill-out factor are q = 0.503(±0.003) and f = 10.8%(±0.1%), respectively. This indicates that AH Tau is in weak contact. For the weak-contact binary AO Cam, BVI light curves clearly show a difference in the heights of the maxima (i.e., the O'Connell effect), which may be explained by spot activity. By analyzing the O - C curves for AO Cam and AH Tau, it is found that the orbital periods appear to show a secular period decrease with a cyclic variation. The observed period modulation is ?P/P ~ 10-6. For AO Cam, the cyclic oscillation with a short period of 7.63(±0.07) yr and a low amplitude of 0fd0019(±0fd0003) may be preferably attributed to the cyclic magnetic activity. The period and amplitude of the cyclic variation for AH Tau are 45.8(±1.1) yr and 0fd0171(±0fd0005), which may more likely result from the light-time effect via a third body. The secular period decrease rates are dP/dt = -1.26(±0.04) × 10-7 days yr -1 for AO Cam and dP/dt = -6.98(±0.07) × 10-8 days yr -1 for AH Tau. This kind of period decrease can be plausibly explained by the mass transfer from the primary to the secondary, and may result in the system evolving into a deep contact configuration.

Yang, Y.-G.; Wei, J.-Y.; Kreiner, J. M.; Li, H.-L.

2010-01-01

185

Dispersion in Neptune's zonal wind velocities from NIR Keck AO observations in July 2009  

NASA Astrophysics Data System (ADS)

We report observations of Neptune made in H-(1.4-1.8 ?m) and K'-(2.0-2.4 ?m) bands on 14 and 16 July 2009 from the 10-m W.M. Keck II Telescope using the near-infrared camera NIRC2 coupled to the Adaptive Optics (AO) system. We track the positions of 54 bright atmospheric features over a few hours to derive their zonal and latitudinal velocities, and perform radiative transfer modeling to measure the cloud-top pressures of 50 features seen simultaneously in both bands. We observe one South Polar Feature (SPF) on 14 July and three SPFs on 16 July at ˜65 °S. The SPFs observed on both nights are different features, consistent with the high variability of Neptune's storms. There is significant dispersion in Neptune's zonal wind velocities about the smooth Voyager wind profile fit of Sromovsky et al. (Icarus, 105:140, 1993), much greater than the upper limit we expect from vertical wind shear, with the largest dispersion seen at equatorial and southern mid-latitudes. Comparison of feature pressures vs. residuals in zonal velocity from the smooth Voyager wind profile also directly reveals the dominance of mechanisms over vertical wind shear in causing dispersion in the zonal winds. Vertical wind shear is not the primary cause of the difference in dispersion and deviation in zonal velocities between features tracked in H-band on 14 July and those tracked in K'-band on 16 July. Dispersion in the zonal velocities of features tracked over these short time periods is dominated by one or more mechanisms, other than vertical wind shear, that can cause changes in the dispersion and deviation in the zonal velocities on timescales of hours to days.

Fitzpatrick, Patrick J.; de Pater, Imke; Luszcz-Cook, Statia; Wong, Michael H.; Hammel, Heidi B.

2014-03-01

186

LDEF (Postflight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray B04  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray B04 The postflight photograph was taken in the SAEF II at KSC prior to removal of the experiment from the LDEF. The experiment trays upper, lower and right flanges have light tan discolorations. The paint dots on clamp blocks located at the centers of the trays upper and right flanges and at the left end of the lower flange have changed from their original white color to a light tan. The SP HVD experiment consist of two identical sets of experiment hardware mounted in three (3) inch deep LDEF experiment trays, one tray is located in the LDEF position B04 adjacent to the LDEF trailing edge and the other is located at LDEF position D10 adjacent to the LDEF leading edge. Each set of SP HVD experiment hardware, self-contained within the experiment tray, consist of six (6) fiberglass reinforced epoxy modules carrying charged dielectric samples on top and the power supplies and electronics below. Four (4) dielectric samples, Kapton with Vapor Deposited Aluminum on one side (VDA-Kapton), are bonded to each of the fiberglas modules with a silver filled conductive epoxy. The spaces between the dielectric sample covered modules and between the modules and the tray flanges are covered by strips of VDA-Kapton attached with acrylic transfer adhesive and Kapton tape. Each experiment tray also contain two solar cell modules. Power for the experiment is provided by LiSO2 batteries supplied by the LDEF Project. The experiment was assembled using non-magnetic stainless steel fasteners. The SP HVD experiment appears to be intact with no apparent physical damage from exposure to the space environment. The white paint around the outer edges of the solar cell modules appears to have changed to a light tan.

1990-01-01

187

LDEF (Flight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray B04  

NASA Technical Reports Server (NTRS)

LDEF (Flight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray B04 The Space Plasma High Voltage Drainage Experiment (SP HVD) flight photograph was taken while the LDEF was attached to the Orbiter's RMS arm prior to berthing in the Orbiter's cargo bay. The paint dots on clamp blocks located at the centers of the trays lower and left flanges and at the right end of the upper flange have changed from their original white color to a dark brown. The SP HVD experiment consist of two identical sets of experiment hardware mounted in three (3) inch deep LDEF experiment trays, one tray is located in the LDEF position B04 adjacent to the LDEF trailing edge and the other is located at LDEF position D10 adjacent to the LDEF leading edge. Each set of SP HVD experiment hardware, self-contained within the experiment tray, consist of six (6) fiberglass reinforced epoxy modules carrying charged dielectric samples on top and the power supplies and electronics below. Four (4) dielectric samples, Kapton with Vapor Deposited Aluminum on one side (VDA-Kapton), are bonded to each of the fiberglass modules with a silver filled conductive epoxy. The spaces between the dielectric sample covered modules and between the modules and the tray flanges are covered by strips of VDA-Kapton attached with acrylic transfer adhesive and Kapton tape. Each experiment tray also contain two solar cell modules. Power for the experiment is provided by LiSO2 batteries supplied by the LDEF Project. The experiment was assembled using non-magnetic stainless steel fasteners. The SP HVD experiment appears to be intact with no apparent physical damage from exposure to the space environment. The lighting is such that changes in material colors is difficult to detect, however, the white paint in the vicinity of the solar cell modules appears to have darkened.

1990-01-01

188

The Hydrography in Shen-ao Bay, North Taiwan, without Thermal Plume  

NASA Astrophysics Data System (ADS)

Located at northern Taiwan, the Shen-ao Bay is characterized by thermal plume of a power plant and fresh water of the Jiu-fen Brook, causing the surface water of high temperature and low salinity which makes a significant stratification against the subsurface water. The power plant was extended in 2008 and stopped discharging warm water for one year, providing an opportunity to survey the hydrographic and current fields of the bay in natural condition. During 2005~2009, there were seven times hydrographic surveys in the bay and four times aside the coast. When the plume appeared, the surface water could be 2~4 degree warmer than the subsurface water. The surface warm water disappeared when the power plant was shutdown. In such a circumstance, the brook water might even cause the surface water cooler than the subsurface water. After the thermal plume was terminated, coastal temperature descended about 8 degree in June-July and 6 degree in August-September. The ADP (Acoustic Doppler Profiler) and CTD surveys disclosed a bottom cold water intrusion which did not relate to the tidal current and almost happened in 2~5 hours after sunset. The observations of hydrographic field together with local winds revealed that the bottom intrusion was induced by the land breath. In summer, the daily intrusion occurred earlier, thicker and staying longer than in winter. Despite the plume existed or not, the temperature profiles in the bay of a depth shallower than 20 m could become a 3-stepwise pattern under the bottom cold water intrusion.

Wu, C.; Hu, J.; Lee, C.

2009-12-01

189

Integrating AO in a performance budget: toward a global system engineering vision  

NASA Astrophysics Data System (ADS)

EAGLE (Extremely large Adaptive telescope for GaLaxy Evolution) is one of the eight E-ELT instrument concepts that was developed as part of the Phase A E-ELT instrument studies. EAGLE is a near-infrared wide field multi object spectrograph1. It includes its own multi-object adaptive optics system (MOAO) and its subsystems are cooled down so as to ensure that the instrument can both achieve the desired spatial resolution and to be sure that the instrument is background limited, as required in the primary science case, to deliver the performance in the K-band. In this paper we discuss the performance matrix developed to allow us to partition and allocate the important characteristics to the various subsystems as well as to describe the process to verify that the current concept design will deliver the required performance. Due to the integrated nature of the instrument, a large number of AO parameters have to be controlled. The performance matrix also has to deal with the added complexity of active optical elements such as the science channel deformable mirrors (DMs). This paper also defines a method of how to convert the ensquared energy (EE) and signal-to-noise ratio (SNR) required by the science cases into the "as designed" wavefront error and the overall residue wavefront error. To ensure successful integration and verification of the next generation instruments for ELT it is of the utmost importance to have method to control and manage the instrument's critical performance characteristics at very early design steps.

Laporte, Philippe; Schnetler, Hermine; Rousset, G.

2010-07-01

190

A forced titration study of the antioxidant and immunomodulatory effects of Ambrotose AO supplement  

PubMed Central

Background Oxidative stress plays a role in acute and chronic inflammatory disease and antioxidant supplementation has demonstrated beneficial effects in the treatment of these conditions. This study was designed to determine the optimal dose of an antioxidant supplement in healthy volunteers to inform a Phase 3 clinical trial. Methods The study was designed as a combined Phase 1 and 2 open label, forced titration dose response study in healthy volunteers (n = 21) to determine both acute safety and efficacy. Participants received a dietary supplement in a forced titration over five weeks commencing with a no treatment baseline through 1, 2, 4 and 8 capsules. The primary outcome measurement was ex vivo changes in serum oxygen radical absorbance capacity (ORAC). The secondary outcome measures were undertaken as an exploratory investigation of immune function. Results A significant increase in antioxidant activity (serum ORAC) was observed between baseline (no capsules) and the highest dose of 8 capsules per day (p = 0.040) representing a change of 36.6%. A quadratic function for dose levels was fitted in order to estimate a dose response curve for estimating the optimal dose. The quadratic component of the curve was significant (p = 0.047), with predicted serum ORAC scores increasing from the zero dose to a maximum at a predicted dose of 4.7 capsules per day and decreasing for higher doses. Among the secondary outcome measures, a significant dose effect was observed on phagocytosis of granulocytes, and a significant increase was also observed on Cox 2 expression. Conclusion This study suggests that Ambrotose AO® capsules appear to be safe and most effective at a dosage of 4 capsules/day. It is important that this study is not over interpreted; it aimed to find an optimal dose to assess the dietary supplement using a more rigorous clinical trial design. The study achieved this aim and demonstrated that the dietary supplement has the potential to increase antioxidant activity. The most significant limitation of this study was that it was open label Phase 1/Phase 2 trial and is subject to potential bias that is reduced with the use of randomization and blinding. To confirm the benefits of this dietary supplement these effects now need to be demonstrated in a Phase 3 randomised controlled trial (RCT). Trial Registration Australian and New Zealand Clinical Trials Register: ACTRN12605000258651

2010-01-01

191

LDEF (Postflight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray D10  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray D10 The postflight photograph was taken in the SAEF II at KSC prior to removal of the experiment from the LDEF. The experiment trays upper, lower and right flanges have light tan discolorations. The paint dots on clamp blocks located at the centers of the trays upper and right flanges and at the left end of the lower flange have changed from their original white color to a light tan. The SP HVD experiment consist of two identical sets of experiment hardware mounted in three (3) inch deep LDEF experiment trays, one tray is located in the LDEF position B04 adjacent to the LDEF trailing edge and the other is located at LDEF position D10 adjacent to the LDEF leading edge. Each set of SP HVD experiment hardware, self-contained within the experiment tray, consist of six (6) fiberglass reinforced epoxy modules carrying charged dielectric samples on top and the power supplies and electronics below. Four (4) dielectric samples, Kapton with Vapor Deposited Aluminum on one side (VDA-Kapton), are bonded to each of the fiberglass modules with a silver filled conductive epoxy. The spaces between the dielectric sample covered modules and between the modules and the tray flanges are covered by strips of VDA-Kapton attached with acrylic transfer adhesive and Kapton tape. Each experiment tray also contain two solar cell modules. Power for the experiment is provided by LiSO2 batteries supplied by the LDEF Project. The experiment was assembled using non-magnetic stainless steel fasteners. The SP HVD experiment in this tray was severely degraded by impingement of atomic oxygen during the long exposure to the space environment. Most of the Kapton polyimide material making up the dielectric samples was completely eroded leaving only the 2000-3000 angstrom Vapor Deposited Aluminum (VDA) layer bonded to the module. The edges of the dielectric surface that survived were taped over by Kapton tape with a silicone adhesive. The Kapton backing eroded leaving the silicone adhesive that protected the Kapton surface beneath. The VDA-Kapton strips used to cover spaces between the modules have degraded substantially and only fragments of the extremely fragile VDA layer remain. The larger fragments of the VDA layer observed in the flight photograph were disturbed during post retrieval operations and became many small aluminum particles. The white paint around the outer edges of the solar cell modules appears to have changed little. Impact craters are visible as black or white specks in many locations on the degraded dielectric surfaces. One of the most noticeable is in the dielectric surface in the upper right corner.

1990-01-01

192

LDEF (Flight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray D10  

NASA Technical Reports Server (NTRS)

LDEF (Flight), AO054 : Space Plasma High-Voltage Drainage Experiment, Tray D10 The Space Plasma High Voltage Drainage Experiment (SP HVD) flight photograph was taken while the LDEF was attached to the Orbiter's RMS arm prior to berthing in the Orbiter's cargo bay. The paint dots on clamp blocks located at the center of the trays right flange and at the right and left ends of the left flange have changed very little from their original white color. The SP HVD experiment consist of two identical sets of experiment hardware mounted in three (3) inch deep LDEF experiment trays, one tray is located in the LDEF position B04 adjacent to the LDEF trailing edge and the other is located at LDEF position D10 adjacent to the LDEF leading edge. Each set of SP HVD experiment hardware, self-contained within the experiment tray, consist of six (6) fiberglass reinforced epoxy modules carrying charged dielectric samples on top and the power supplies and electronics below. Four (4) dielectric samples, Kapton with Vapor Deposited Aluminum on one side (VDA-Kapton), are bonded to each of the fiberglass modules with a silver filled conductive epoxy. The spaces between the dielectric sample covered modules and between the modules and the tray flanges are covered by strips of VDA-Kapton attached with acrylic transfer adhesive and Kapton tape. Each experiment tray also contain two solar cell modules. Power for the experiment is provided by LiSO2 batteries supplied by the LDEF Project. The experiment was assembled using non-magnetic stainless steel fasteners. The SP HVD experiment in this tray was severely degraded by impingement of atomic oxygen during the long exposure to the space environment. Most of the Kapton polyimide material making up the dielectric samples was completely eroded leaving only the 2000-3000 angstrom vapor deposited aluminum layer bonded to the module. The edges of the dielectric surface that survived were taped over by Kapton tape with a silicone adhesive. The Kapton backing eroded leaving the silicone adhesive that protected the Kapton surface beneath. The VDA-Kapton strips used to cover spaces between the modules have degraded substantially and only fragments of the vapor deposited aluminum layer remain attached along the edges. The white paint around the outer edges of the solar cell modules appears to have changed little. Impact craters are visible as black or white specks in many locations on the degraded dielectric surfaces. One of the most noticeable is in the dielectric surface in the upper right corner.

1990-01-01

193

Future change of water vaiables from HadGEM2-AO simulation  

NASA Astrophysics Data System (ADS)

Complex global models developed for climate prediction are now applied to the future climate projection in a number of global modeling centers around the world. In climate prediction aspects, an atmosphere-ocean coupled model (one-tier climate system) has been recognized to exhibit useful skill for a global or certain regions (Graham et al., 2005). Wang et al. (2005) demonstrates that an AGCM coupled with an ocean model, simulates realistic SST-rainfall relationships for the Asia during the summer period. Also the transition from two-tier to one-tier approach in climate prediction are mainly caused by recent progresses in development of coupled climate models and enlargement of understanding air-sea interactions obtained from international collaborative efforts such as TOGA (the Tropical Ocean-Global Atmosphere) program (Wang et al., 2009). Meanwhile, water resource including river outflow in association with surface and sub-surface water flow is an important part of the global hydrological cycle, and is affected by climate variability and change through recharge processes (Chen et al., 2002), as well as by human interventions in many locations (Petheram et al., 2001). Also, water is critical resource to the social, economic and environmental aspects, and advances of these core elements requires improved water resource management. Better management and use of water need to abundant real time hydro-meteorological (river and weather) information as well as accurate water resource forecasting (Barrett, 1990). For this reason, many studies have recently carrying out the water resource prediction and estimation using hydrology and climate model. For example, Shiklomanov et al. (2011) predicted that water resource in Russian territory increases about 8-10% during 2010-2020 using the unit hydrograph (UH) model based on hydrologic rainfall-runoff model. Anderson et al. (2000) explained the probabilistic seasonal prediction of drought with a simplified climate model coupled hydrology-atmosphere for water resource planning. Arora et al. (1999) and Oki and Sud (1998) developed a method for routing river flows through GCM grid cells. Accordingly, reliable forecasts are expected to help water managers and users with long lead time decisions, leading to greater water use efficiency and better risk management (Wang, 2012). SO, we analysed hydrological cycle and drought index from precipitation, evaporation, runoff, soil moisture, river outflow, and so on using atmosphere-ocean coupled model which called by HadGEM2-AO. Details and added information by this climate projection system about the future water cycle's change will be presented at the workshop. Acknowledgments: This research has been supported by project NIMR-2013-B-2 of the National Institute of Meteorological Research in Korea Meteorological Administration.

Kim, Moon-Hyun; Kang, Hyun-Suk; Lee, Johan; Baek, Hee-Jeong; Cho, Chunho

2013-04-01

194

LDEF (Postflight), AO175 : Evaluation of Long-Duration Exposure to the Natural Space Environment on  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO175 : Evaluation of Long-Duration Exposure to the Natural Space Environment on Graphite-Polyimide and Graphite-Epoxy Mechanical Properties, Tray A07 The postflight photograph was taken in the Operations and Control (O&C) facility after the LDEF had been transferred from the KSC Payload Transporter to the LDEF Assembly and Transport System (LATS) and shows more detail than the flight photograph. The areas on the aluminum mounting strips where the coating has been scraped and/or abraided can be seen in greater detail under the better lighting conditions. The coating color remains essentially the same. The white paint dots on the tray clampblocks have changed little from the orginal color. PMR-15 Graphite-Polyimide Panel (precured) - The PMR-15 graphite-polyimide laminated panel (T40T30060-009) postflight photograph provides more detail than the flight photograph. The geometric pattern seen on the flight photograph is not visible, however, the horizontal lines, cracks and/or crazing, observed previously are better defined. A gray haze or dust appears to cover the gray/brown panel surface. The yellow colored identification numbers seem to be a little lighter than in the flight photograph but the white marking in the upper left corner do not appear to have changed. Scratch marks/abrasions on the lower left edge of panel were on prelaunch photographs. F-178/T300 Graphite-Polyimide Panel (cocured) - The 178/T300 graphite-polyimide panel (T40T30060-005) seems to have changed in color from the light gray in the flight photograph to a brownish gray. The yellow identification numbers seem lighter while the white marking in the upper left corner appear brighter. The fine horizontal lines, cracks and/or crazing, are still visible on the panel surface. F178/T300 Graphite-Polyimide Panel (precured) - The 178/T300 graphite-polyimide laminated panel (T40T30060-001) seems to have changed to a brownish gray from the light gray color seen in the flight photograph. The yellow identification numbers and the white marking seen on the lower right corner of the panel appear the same as in the flight photograph. The fine horizontal lines, cracks and/or crazing, are still visible on the panel surface.

1990-01-01

195

High energy resolution observation of the Crab and AO535 plus 26 in the hard X-ray range  

NASA Technical Reports Server (NTRS)

A number of uncertainties exist currently regarding the existence of gamma-ray lines in the Crab spectrum. An investigation was, therefore, conducted, and the Crab was observed for eight hours during a balloon flight from Palestine, TX, on September 26, 1980. It appeared that the binary source AO535 plus 26 contaminated the Crab data. It was, however, possible to separate the two sources. The obtained results are discussed and evaluated. It is found that the possibility of a line at 73 keV with the intensity reported by Ling et al. (1979) can be excluded for the obtained data. The 400 keV line cannot be ruled out. The results concerning AO535 plus 26 are very different from those previously obtained.

Hameury, J. M.; Boclet, D.; Durouchoux, P.; Cline, T.; Teegarden, B.; Tueller, J.; Paciesas, W.; Haymes, R.

1982-01-01

196

Knee Osteochondritis Dissecans Treated by the AO Hook Fixation System: A Four Year Follow-Up of an Alternative Technique  

PubMed Central

Surgical fixation is recommended for stable osteochondritis dissecans (OCD) lesions that have failed nonoperative management and for all unstable lesions. In this study we set out to describe and evaluate an alternative method of surgical fixation for such lesions. Five knees with unstable OCD lesions in four male adolescent patients with open physes were treated with the AO Hook Fixation System. The outcome was evaluated both clinically and with three separate outcome systems (IKDC 2000, KOOS, Lysholm) at one and a mean four year follow-up. We demonstrated excellent clinical results in all patients. At four years, all scoring systems demonstrated statistically significant improvement when compared to the preoperative status. Our study suggests that the AO Hook Fixation System is an alternative method of surgical intervention with comparable medium term results with other existing modes of fixation and the added biomechanical advantage of the absence of distracting forces during hardware removal.

Pengas, Ioannis P; Assiotis, Angelos; Kokkinakis, Michail; Khan, Wasim S; Meyers, Paul; Arbuthnot, James; Mcnicholas, Michael J

2014-01-01

197

Classification of Orbital Fractures Using the AO/ASIF System in a Population Surveillance Cohort of Traumatic Optic Neuropathy.  

PubMed

Abstract Purpose: In our prospective nationwide surveillance study of traumatic optic neuropathy (TON) in the United Kingdom, the prevalence of orbital fractures was found to be 39% (47/121). The prevalence of skull fractures was 7.4% (9/121). This study aims to identify the association of craniofacial-orbital fractures with the severity of visual loss. Methods: TON patients who sustained orbital fractures were identified prospectively by population-based active surveillance through the British Ophthalmic Surveillance Unit over a 2-year period. Available CT scans were classified by a head and neck radiologist according to the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) scheme: the face was divided into 4 units; fractures in each unit were graded according to displacement (A-C) and severity (1.1-3.3). Correlation between severity of craniofacial orbital fractures and visual acuity as well as number of fractured units and visual acuity were evaluated. Results: Twelve of the 25 patients (48%) with imaging available had adequate high resolution craniofacial CT imaging for review and classification using the AO/ASIF system (i.e. 48 classifiable units). Three of 48 (6%) units were undisplaced (grade A), 18 of 48 (29%) units were minimally displaced (grade B), and 4 of 48 (8%) units had largely displaced (grade C) fractures. Twenty-three units (47.9%) had no fractures; 5 patients had radiological evidence of optic canal fractures. Poor visual acuities positively correlated with severity of fractures graded using the AO/ASIF classification (Spearman's rho?=?0.95, p?=?0.05) and number of fractured units (Spearman's rho?=?1.0, p?AO/ASIF classification system provides a uniform method in the assessment of orbital fractures which correlates with visual outcome in TON. PMID:24694248

Ong, Hon Shing; Qatarneh, Dania; Ford, Rebecca L; Lingam, Ravi Kumar; Lee, Vickie

2014-08-01

198

Radial artery pseudoaneurysm complication from use of AO\\/ASIF volar distal radius plate: A case report  

Microsoft Academic Search

A case of pseudoaneurysm of the radial artery after fixation of a distal radius using the AO\\/ASIF volar distal radius plate system is presented. This unusual complication resulted from inadequate fracture stabilization and plate preparation. Technical tips on plate shortening and preparation of the cut ends are emphasized. (J Hand Surg 2001;26A:448-453. Copyright © 2001 by the American Society for

Khiem D Dao; Eric Venn-Watson; Alexander Y Shin

2001-01-01

199

ShaneAO: an enhanced adaptive optics and IR imaging system for the Lick Observatory 3-meter telescope  

NASA Astrophysics Data System (ADS)

The Lick Observatory 3-meter telescope has a history of serving as a testbed for innovative adaptive optics techniques. In 1996, it became one of the first astronomical observatories to employ laser guide star (LGS) adaptive optics as a facility instrument available to the astronomy community. Work on a second-generation LGS adaptive optics system, ShaneAO, is well underway, with plans to deploy on telescope in 2013. In this paper we discuss key design features and implementation plans for the ShaneAO adaptive optics system. Once again, the Shane 3-m will host a number of new techniques and technologies vital to the development of future adaptive optics systems on larger telescopes. Included is a woofer-tweeter based wavefront correction system incorporating a voice-coil actuated, low spatial and temporal bandwidth, high stroke deformable mirror in conjunction with a high order, high bandwidth MEMs deformable mirror. The existing dye laser, in operation since 1996, will be replaced with a fiber laser recently developed at Lawrence Livermore National Laboratories. The system will also incorporate a high-sensitivity, high bandwidth wavefront sensor camera. Enhanced IR performance will be achieved by replacing the existing PICNIC infrared array with an Hawaii 2RG. The updated ShaneAO system will provide opportunities to test predictive control algorithms for adaptive optics. Capabilities for astronomical spectroscopy, polarimetry, and visible-light adaptive optical astronomy will be supported.

Kupke, Renate; Gavel, Donald; Roskosi, Constance; Cabak, Gerald; Cowley, David; Dillon, Daren; Gates, Elinor L.; McGurk, Rosalie; Norton, Andrew; Peck, Michael; Ratliff, Christopher; Reinig, Marco

2012-07-01

200

Io Volcanic Activity Since 2003 As Seen By 8-10-m-class Telescopes Equipped With Adaptive Optics (ao)  

NASA Astrophysics Data System (ADS)

Io, most volcanic place in the our Solar System, has been monitored since 2003 on a semi-irregular basis using the Keck II and the Gemini North Adaptive Optics (AO) systems equipped with a near infrared (NIR) camera sensitive to 5 um. We present a global view of Io volcanic activity, identifying permanent hot spots, sporadic outbursts, and possible surface changes from these observations. AO observations were also obtained at the time of the New Horizons flyby in early 2007, from these data we can constrain the style of volcanism at specific volcanic centers. Finally, we discuss the relatively quiescent state of Io volcanism observed over the past 2 years. The monitoring of Io's volcanic activity will continue through 2016, which includes the arrival of the Juno spacecraft in July of that year, and beyond. An ever-increasing timeline of volcanic activity and thermal emission variability continues to be constructed and which will be further complimented by data obtained by other missions to the Jupiter system (such as JUICE, or a dedicated Europa or Io mission). Until these missions, however, the task of monitoring Io's volcanic activity will be from large, AO-enabled ground-based telescopes. The support of the NASA Planetary Outer Planets Research Program is acknowledged.

Marchis, Franck; Davies, A.

2012-10-01

201

HIGH RESOLUTION H{alpha} IMAGES OF THE BINARY LOW-MASS PROPLYD LV 1 WITH THE MAGELLAN AO SYSTEM  

SciTech Connect

We utilize the new Magellan adaptive optics system (MagAO) to image the binary proplyd LV 1 in the Orion Trapezium at H{alpha}. This is among the first AO results in visible wavelengths. The H{alpha} image clearly shows the ionization fronts, the interproplyd shell, and the cometary tails. Our astrometric measurements find no significant relative motion between components over {approx}18 yr, implying that LV 1 is a low-mass system. We also analyze Large Binocular Telescope AO observations, and find a point source which may be the embedded protostar's photosphere in the continuum. Converting the H magnitudes to mass, we show that the LV 1 binary may consist of one very-low-mass star with a likely brown dwarf secondary, or even plausibly a double brown dwarf. Finally, the magnetopause of the minor proplyd is estimated to have a radius of 110 AU, consistent with the location of the bow shock seen in H{alpha}.

Wu, Y.-L.; Close, L. M.; Males, J. R.; Follette, K.; Morzinski, K.; Kopon, D.; Rodigas, T. J.; Hinz, P. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Puglisi, A.; Esposito, S.; Pinna, E.; Riccardi, A.; Xompero, M.; Briguglio, R., E-mail: yalinwu@email.arizona.edu [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)

2013-09-01

202

A possible cause of the AO polarity reversal from winter to summer in 2010 and its relation to hemispheric extreme summer weather  

NASA Astrophysics Data System (ADS)

In 2010, the Northern Hemisphere, in particular Russia, Europe and Japan, experienced an abnormally hot summer characterized by record-breaking warm temperatures and associated with a strongly positive Arctic Oscillation (AO). In contrast, in winter 2009/2010, the continent suffered from anomalously cold weather associated with a record-breaking negative AO. The winter-to-summer of the AO index during 2009/2010 evolved as follows: a strongly negative wintertime AO index continued until May, after which it abruptly changed, becoming strongly positive in July and continuing so until the beginning of August. The abrupt change of the AO index from strongly negative to strongly positive in 2010 thus corresponded to the change from the abnormally cold winter of 2009/2010 to the abnormally hot summer of 2010, which shows that the AO index is a good indicator of abnormal weather on a planetary-scale, and that extra-seasonal prediction of the AO is a key to long-term forecasting. In this study, we therefore aimed to examine the cause of the 2010 change in the AO index from strongly negative to strongly positive. We suggest that an oceanic memory of the strongly negative wintertime AO may have influenced the strongly positive summertime AO. The winter sea surface temperatures (SST) in the North Atlantic Ocean showed a tripolar anomaly pattern which is warm SST anomalies over the tropics and high latitudes and cold SST anomalies over the midlatitudes. The strongly negative wintertime AO would cause the warm SST anomaly in this region. The warm SST anomalies continued into summer 2010 because of the large oceanic heat capacity. In May and June, the heat flux anomaly changed from downward to upward in the tropics, and in July and August, the center of the upward anomaly moved westward. The area of the upward heat flux anomaly coincided with the area of the warm SST anomaly from May to August. The numerical model experiment showed that the tripolar SST pattern resulted in an anomalous height and wind pattern that caused a blocking high over Europe. The observed wave activity flux also seems to emanate from Europe. This midlatitude atmospheric response implies that strengthening of the positive geopotential anomalies over Europe was associated with the Atlantic tripolar SST anomaly. The positive geopotential anomaly in the area of the polar jet stream caused eastward propagation of Rossby waves, and the exceeding amplification of Rossby waves might have led to the formation of blocking anticyclones. As a consequence of these interactions, the positive AO pressure pattern can continue for a long time. Thus, a possible cause of the AO polarity reversal might be the "memory" of the negative winter AO in the North Atlantic Ocean, suggesting an interseasonal linkage of the AO in which the oceanic memory of a wintertime negative AO induces a positive AO in the following summer. Understanding of this interseasonal linkage may aid in the long-term prediction of such abnormal summer events. If this reversal pattern recurs, it might be possible to predict the summertime AO from the wintertime AO. Main parts of this study were published in Climatic Dynamics by Otomi et al, (2012).

Otomi, Y.; Tachibana, Y.; Nakamura, T.

2012-12-01

203

Research in particle physics. [Dept. of Physics, Boston Univ  

SciTech Connect

Research accomplishments and current activities of Boston University researchers in high energy physics are presented. Principal areas of activity include the following: detectors for studies of electron[endash]positron annihilation in colliding beams; advanced accelerator component design, including the superconducting beam inflector, electrostatic quadrupoles, and the electrostatic muon kicker''; the detector for the MACRO (Monopole, Astrophysics, and Cosmic Ray Observatory) experiment; neutrino astrophysics and the search for proton decay; theoretical particle physics (electroweak and flavor symmetry breaking, hadron collider phenomenology, cosmology and astrophysics, new field-theoretic models, nonperturbative investigations of quantum field theories, electroweak interactions); measurement of the anomalous magnetic moment of the muon; calorimetry for the GEM experiment; and muon detectors for the GEM experiment at the Superconducting Super Collider.

Not Available

1992-09-01

204

UniverCity: Building a New Green Neighborhood  

Microsoft Academic Search

If North American cities are to make the significant tech- nological, physical, and social-cultural shifts necessary to reduce greenhouse gas emissions, urban form will have to change dramatically. Many urban regions are beginning to rise to this challenge, taking steps to control sprawl, air and water pollution, and the fragmentation of urban ecosys- tems. One region that has made notable

Cynthia Girling

205

Technical progress report. [Nuclear Physics Lab. , Univ. of Colorado  

SciTech Connect

This report summarizes the work carried out at the Nuclear Physics Laboratory of the University of Colorado during the period November 1, 1977 to November 1, 1978, under Contract EY-76-C-02-0535.A002 between the University of Colorado and the United States Department of Energy. The research activities of the Laboratory spanned a broad range of interests over the past year. Numerous topics in charged-particle spectroscopy and reaction studies, neutron time-of-flight measurements, and gamma-ray investigations performed at the cyclotron laboratory are covered in this report. In addition, several items in intermediate energy nuclear physics as studied at Los Alamos and Indiana University by members of the Laboratory are reported. The efforts in nuclear theory include studies in nuclear reaction mechanisms and pion scattering as related to the experimental program. Information is also included on apparatus and facility development, cyclotron operation, outside users, publications, and reports. Separate abstracts were written for thirty items in this report having significant amounts of data. (RWR)

Not Available

1978-11-01

206

Deexcitation processes in nuclear reactions. [Dept. of Chemistry, Purdue Univ  

SciTech Connect

During the past year, our research program has involved continuing analysis of Fermilab E-735, search for quark-gluon plasma (QGP) in {bar p}-p collisions; continuing study of target fragments produced in the interaction of copper with intermediate-energy heavy ions; an exclusive study of multifragmentation using reverse kinematics at the Bevalac; and detector development for the STAR detector at RHIC.

Porile, N.T.

1992-09-01

207

Triangular covariance factorizations for. Ph.D. Thesis. - Calif. Univ.  

NASA Technical Reports Server (NTRS)

An improved computational form of the discrete Kalman filter is derived using an upper triangular factorization of the error covariance matrix. The covariance P is factored such that P = UDUT where U is unit upper triangular and D is diagonal. Recursions are developed for propagating the U-D covariance factors together with the corresponding state estimate. The resulting algorithm, referred to as the U-D filter, combines the superior numerical precision of square root filtering techniques with an efficiency comparable to that of Kalman's original formula. Moreover, this method is easily implemented and involves no more computer storage than the Kalman algorithm. These characteristics make the U-D method an attractive realtime filtering technique. A new covariance error analysis technique is obtained from an extension of the U-D filter equations. This evaluation method is flexible and efficient and may provide significantly improved numerical results. Cost comparisons show that for a large class of problems the U-D evaluation algorithm is noticeably less expensive than conventional error analysis methods.

Thornton, C. L.

1976-01-01

208

The CLUES project: Constrained Local UniversE Simulations  

NASA Astrophysics Data System (ADS)

Constrained simulations of the Local Universe are an invaluable tool to investigate many aspects of dark halo and galaxy formation in environments that look pretty much like the the one our Milky Way resides. In this way, we can minimize the effect of cosmic variance when comparing the results of numerical simulations with observations of the Local Volume (LV, a sphere of 7-8 Mpc around us). In this paper we present the CLUES Project, an international collaboration whose main goal is to produce realistic cosmological simulations of the Local Universe, by imposing observational constrains on the mass and velocity fields of the initial random gaussian fluctuation realizations. The advantage of this technique is that we reproduce the large scale structures regardless whether we change the cosmological model, or the nature of dark matter candidates. In this regard, we can then make reliable comparisons between simulation outputs and draw conclusions that are less affected by cosmic variance.

Yepes, G.; Martínez-Vaquero, L. A.; Gottlöber, S.; Hoffman, Y.

2009-10-01

209

Experimental particle physics. [Dept. of Physics, Drexel Univ  

SciTech Connect

The goals of this research are the experimental testing of fundamental theories of physics beyond the standard model and the exploration of cosmic phenomena through the techniques of particle physics. We are working on the MACRO experiment, which employs a large-area underground detector to search fore grand unification magnetic monopoles and dark matter candidates and to study cosmic ray muons as well as low- and high-energy neutrinos; the Chooz experiment to search for reactor neutrino oscillations at a distance of 1 km from the source; a new proposal (the Perry experiment) to construct a one-kiloton liquid scintillator in the Fairport, Ohio underground facility IMB to study neutrino oscillations with a 13 km baseline; and development of technology for improved liquid scintillators and for very-low-background materials in support of the MACRO and Perry experiments and for new solar neutrino experiments.

Steinberg, R.I.; Lane, C.E.

1992-09-01

210

Effect of Ambrotose AO® on resting and exercise-induced antioxidant capacity and oxidative stress in healthy adults  

PubMed Central

Background The purpose of this investigation was to determine the effects of a dietary supplement (Ambrotose AO®) on resting and exercise-induced blood antioxidant capacity and oxidative stress in exercise-trained and untrained men and women. Methods 25 individuals (7 trained and 5 untrained men; 7 trained and 6 untrained women) received Ambrotose AO® (4 capsules per day = 2 grams per day) or a placebo for 3 weeks in a random order, double blind cross-over design (with a 3 week washout period). Blood samples were collected at rest, and at 0 and 30 minutes following a graded exercise treadmill test (GXT) performed to exhaustion, both before and after each 3 week supplementation period. Samples were analyzed for Trolox Equivalent Antioxidant Capacity (TEAC), Oxygen Radical Absorbance Capacity (ORAC), malondialdehyde (MDA), hydrogen peroxide (H2O2), and nitrate/nitrite (NOx). Quality of life was assessed using the SF-12 form and exercise time to exhaustion was recorded. Resting blood samples were analyzed for complete blood count (CBC), metabolic panel, and lipid panel before and after each 3 week supplementation period. Dietary intake during the week before each exercise test was recorded. Results No condition effects were noted for SF-12 data, for GXT time to exhaustion, or for any variable within the CBC, metabolic panel, or lipid panel (p > 0.05). Treatment with Ambrotose AO® resulted in an increase in resting levels of TEAC (p = 0.02) and ORAC (p < 0.0001). No significant change was noted in resting levels of MDA, H2O2, or NOx (p > 0.05). Exercise resulted in an acute increase in TEAC, MDA, and H2O2 (p < 0.05), all which were higher at 0 minutes post exercise compared to pre exercise (p < 0.05). No condition effects were noted for exercise related data (p > 0.05), with the exception of ORAC (p = 0.0005) which was greater at 30 minutes post exercise for Ambrotose AO® compared to placebo. Conclusion Ambrotose AO® at a daily dosage of 4 capsules per day increases resting blood antioxidant capacity and may enhance post exercise antioxidant capacity. However, no statistically detected difference is observed in resting or exercise-induced oxidative stress biomarkers, in quality of life, or in GXT time to exhaustion.

2010-01-01

211

Design, Implementation, and On-Sky Performance of an Advanced Apochromatic Triplet Atmospheric Dispersion Corrector for the Magellan Adaptive Optics System and VisAO Camera  

NASA Astrophysics Data System (ADS)

We present the novel design, laboratory verification, and on-sky performance of our advanced triplet atmospheric dispersion corrector (ADC), an important component of the Magellan Adaptive Optics system (MagAO), which recently achieved first light in December 2012. High-precision broadband (0.5--1.0 ?m) atmospheric dispersion correction at visible wavelengths is essential both for wavefront sensing (WFS) on fainter guide stars, and for performing visible AO science using our VisAO science camera. At 2 airmasses (60° from zenith) and over the waveband 500--1000 nm, our triplet design produces a 57% improvement in geometric rms spot size, a 33% improvement in encircled energy at 20? radius, and a 62% improvement in Strehl ratio when compared to a conventional doublet design. This triplet design has been fabricated, tested in the lab, and integrated into the MagAO WFS and the VisAO science camera. We present on-sky results of the ADC in operation with the MagAO system. We also present a zero-beam-deviation triplet ADC design, which will be important to future AO systems that require precise alignment of the optical axis over a large range of airmasses in addition to diffraction-limited broadband dispersion correction.

Kopon, Derek; Close, Laird M.; Males, Jared R.; Gasho, Victor

2013-08-01

212

CRCHD - CRCHD Research - Morehouse School of Med/Tuskegee Univ/Univ. of Alabama Cancer Center Partnership  

Cancer.gov

The partnership between Morehouse School of Medicine (MSM), Tuskegee University (TU) and the UAB Comprehensive Cancer Center (UABCCC) builds upon an existing partnership between these 3 institutions. Each institution brings to the table a unique set of strengths that effectively supplement the inherent weaknesses of the others. The Partnership is geographically located within the heart of the Southeast, a region with a large, historically underserved, African-American population.

213

Inter-observer reliability assessment of the Schatzker, AO/OTA and three-column classification of tibial plateau fractures  

PubMed Central

Background The purpose of our study was to evaluate inter-observer reliability of the Three-Column classifications with conventional Schatzker and AO/OTA of Tibial Plateau Fractures. Methods 50 cases involving all kinds of the fracture patterns were collected from 278 consecutive patients with tibial plateau fractures who were internal fixed in department of Orthopedics and Trauma III in Shanghai Sixth People’s Hospital. The series were arranged randomly, numbered 1 to 50. Four observers were chosen to classify these cases. Before the research, a classification training session was held to each observer. They were given as much time as they required evaluating the radiographs accurately and independently. The classification choices made at the first viewing were not available during the second viewing. The observers were not provided with any feedback after the first viewing. The kappa statistic was used to analyze the inter-observer reliability of the three fracture classification made by the four observers. Results The mean kappa values for inter-observer reliability regarding Schatzker classification was 0.567 (range: 0.513–0.589), representing “moderate agreement”. The mean kappa values for inter-observer reliability regarding AO/ASIF classification systems was 0.623 (range: 0.510–0.710) representing “substantial agreement”. The mean kappa values for inter-observer reliability regarding Three-Column classification systems was 0.766 (range: 0.706–0.890), representing “substantial agreement”. Conclusion Three-Column classification, which is dependent on the understanding of the fractures using CT scans as well as the 3D reconstruction can identity the posterior column fracture or fragment. It showed “substantial agreement” in the assessment of inter-observer reliability, higher than the conventional Schatzker and AO/OTA classifications. We finally conclude that Three-Column classification provides a higher agreement among different surgeons and could be popularized and widely practiced in other clinical centers.

2013-01-01

214

A novel mammalian expression system derived from components coordinating nicotine degradation in arthrobacter nicotinovorans pAO1  

PubMed Central

We describe the design and detailed characterization of 6-hydroxy-nicotine (6HNic)-adjustable transgene expression (NICE) systems engineered for lentiviral transduction and in vivo modulation of angiogenic responses. Arthrobacter nicotinovorans pAO1 encodes a unique catabolic machinery on its plasmid pAO1, which enables this Gram-positive soil bacterium to use the tobacco alkaloid nicotine as the exclusive carbon source. The 6HNic-responsive repressor-operator (HdnoR-ONIC) interaction, controlling 6HNic oxidase production in A.nicotinovorans pAO1, was engineered for generic 6HNic-adjustable transgene expression in mammalian cells. HdnoR fused to different transactivation domains retained its ONIC-binding capacity in mammalian cells and reversibly adjusted transgene transcription from chimeric ONIC-containing promoters (PNIC; ONIC fused to a minimal eukaryotic promoter [Pmin]) in a 6HNic-responsive manner. The combination of transactivators containing various transactivation domains with promoters differing in the number of operator modules as well as in their relative inter-ONIC and/or ONIC-Pmin spacing revealed steric constraints influencing overall NICE regulation performance in mammalian cells. Mice implanted with microencapsulated cells engineered for NICE-controlled expression of the human glycoprotein secreted placental alkaline phosphatase (SEAP) showed high SEAP serum levels in the absence of regulating 6HNic. 6HNic was unable to modulate SEAP expression, suggesting that this nicotine derivative exhibits control-incompatible pharmacokinetics in mice. However, chicken embryos transduced with HIV-1-derived self-inactivating lentiviral particles transgenic for NICE-adjustable expression of the human vascular endothelial growth factor 121 (VEGF121) showed graded 6HNic response following administration of different 6HNic concentrations. Owing to the clinically inert and highly water-soluble compound 6HNic, NICE-adjustable transgene control systems may become a welcome alternative to available drug-responsive homologs in basic research, therapeutic cell engineering and biopharmaceutical manufacturing.

Malphettes, Laetitia; Weber, Cornelia C.; El-Baba, Marie Daoud; Schoenmakers, Ronald G.; Aubel, Dominique; Weber, Wilfried; Fussenegger, Martin

2005-01-01

215

Search of Binary Jupiter-Trojan Asteroids with Laser Guide Star AO systems: a moon around 624 Hektor  

NASA Astrophysics Data System (ADS)

In 2006, we initiated a search for multiple asteroids in Jupiter Trojan L4 population with Laser Guide Star Adaptive Optics (LGS AO) technology on 8-10m class telescopes. To maximize the chance of detecting companion, we prioritized Trojan asteroids that could be member of collisional families in our search (see the PeTrA project and Beaugé and Roig (A&A, 2001)). Our first night was performed on July 17 2006 UT with the Keck LGS AO system. Twenty targets up to the 18th magnitude in R band were observed mostly in Kp broadband filter with an angular resolution 0.06 arcsec. Images of 624 Hektor, our brightest target (predicted V=14.4) revealed the presence of a moonlet companion (Marchis et al., IAU, 2006, provisional designation S/2006(624)1) located at 0.36” ( 1150 km) from the primary with a peak SNR 25. The resolved primary has a bilobated shape, but it is unclear if the primary is a contact or separated binary. It can be approximated as an ellipse with major and minor axes 2a = 350 km and 2b = 210 km (108 and 65 milli-arcseconds). The pole solution ?=329°, ?=-25° in ecliptic B1950 (Magnusson 1989, and updated table) is in agreement with the observations. Based on the integrated brightness ratio between the moonlet and the primary of about 6.5, the diameter of S/2006(624)1 is estimated to be about 15 km. Additional observations will be recorded using the Keck and Gemini LGS AO system in Aug-Sept. 2006 aiming to estimate the orbit of the moonlet. The conditions of observations seem optimal since the system will be seen pole-on during this period. 624 Hektor is the first binary asteroid found in the L4 point and the first Trojan possessing a moonlet companion. The result of this campaign of observations, including Aug-Sept. observations, will be discussed.

Marchis, Franck; Berthier, J.; Wong, M. H.; Descamps, P.; Hestroffer, D.; Colas, F.; de Pater, I.; Vachier, F.

2006-09-01

216

Snow anomaly events from historical documents in eastern China during the past two millennia and implication for low-frequency variability of AO\\/NAO and PDO  

Microsoft Academic Search

Models and instrumental data indicate that the spatial and temporal variations of snow cover are significantly related to atmospheric circulation (e.g. the AO\\/NAO). Here, we present historical snow anomaly events during the past two millennia that provide a unique temporal window to studying long-term AO\\/NAO, a prominent phenomenon in wintertime. Direct descriptions such as “no snow during the winter” and

Guoqiang Chu; Qing Sun; Xiaohua Wang; Junying Sun

2008-01-01

217

Snow anomaly events from historical documents in eastern China during the past two millennia and implication for low-frequency variability of AO\\/NAO and PDO  

Microsoft Academic Search

Models and instrumental data indicate that the spatial and temporal variations of snow cover are significantly related to atmospheric circulation (e.g. the AO\\/NAO). Here, we present historical snow anomaly events during the past two millennia that provide a unique temporal window to studying long-term AO\\/NAO, a prominent phenomenon in wintertime. Direct descriptions such as ``no snow during the winter'' and

Guoqiang Chu; Qing Sun; Xiaohua Wang; Junying Sun

2008-01-01

218

An Aspergillus oryzae CCAAT-binding protein, AoCP, is involved in the high-level expression of the Taka-amylase A gene  

Microsoft Academic Search

Aspergillus oryzae contains a nuclear protein designated AoCP, which binds specifically to a CCAAT sequence in the promoter region of the A. oryzae Taka-amylase A gene. A gene encoding a homologue of Aspergillus nidulans HAPC, a subunit of the A. nidulans CCAAT binding complex, was isolated from A. oryzae and designated AohapC. AoHAPC comprises 215 amino acids and shows 84%

Akimitsu Tanaka; Masashi Kato; Hideki Hashimoto; Ken-ichi Kamei; Fumiko Naruse; Peter Papagiannopoulos; Meryl A. Davis; Michael J. Hynes; Tetsuo Kobayashi; Norihiro Tsukagoshi

2000-01-01

219

Production and characterisation of AoSOX2 from Aspergillus oryzae, a novel flavin-dependent sulfhydryl oxidase with good pH and temperature stability.  

PubMed

Sulfhydryl oxidases have found application in the improvement of both dairy and baking products due to their ability to oxidise thiol groups in small molecules and cysteine residues in proteins. A genome mining study of the available fungal genomes had previously been performed by our group in order to identify novel sulfhydryl oxidases suitable for industrial applications and a representative enzyme was produced, AoSOX1 from Aspergillus oryzae (Faccio et al. BMC Biochem 11:31, 2010). As a result of the study, a second gene coding for a potentially secreted sulfhydryl oxidase, AoSOX2, was identified in the genome of A. oryzae. The protein AoSOX2 was heterologously expressed in Trichoderma reesei and characterised with regard to both biochemical properties as well as preliminary structural analysis. AoSOX2 showed activity on dithiothreitol and glutathione, and to a lesser extent on D/L-cysteine and beta-mercaptoethanol. AoSOX2 was a homodimeric flavin-dependent protein of approximately 78 kDa (monomer 42412 Da) and its secondary structure presents alpha-helical elements. A. oryzae AoSOX2 showed a significant stability to pH and temperature. PMID:21327412

Faccio, Greta; Kruus, Kristiina; Buchert, Johanna; Saloheimo, Markku

2011-05-01

220

THE FIRST CIRCUMSTELLAR DISK IMAGED IN SILHOUETTE AT VISIBLE WAVELENGTHS WITH ADAPTIVE OPTICS: MagAO IMAGING OF ORION 218-354  

SciTech Connect

We present high-resolution adaptive optics (AO) corrected images of the silhouette disk Orion 218-354 taken with Magellan AO (MagAO) and its visible light camera, VisAO, in simultaneous differential imaging mode at H?. This is the first image of a circumstellar disk seen in silhouette with AO and is among the first visible light AO results in the literature. We derive the disk extent, geometry, intensity, and extinction profiles and find, in contrast with previous work, that the disk is likely optically thin at H?. Our data provide an estimate of the column density in primitive, ISM-like grains as a function of radius in the disk. We estimate that only ?10% of the total submillimeter derived disk mass lies in primitive, unprocessed grains. We use our data, Monte Carlo radiative transfer modeling, and previous results from the literature to make the first self-consistent multiwavelength model of Orion 218-354. We find that we are able to reproduce the 1-1000 ?m spectral energy distribution with a ?2-540 AU disk of the size, geometry, small versus large grain proportion, and radial mass profile indicated by our data. This inner radius is a factor of ?15 larger than the sublimation radius of the disk, suggesting that it is likely cleared in the very interior.

Follette, Katherine B.; Close, Laird M.; Males, Jared R.; Wu, Ya-Lin; Morzinski, Katie M.; Hinz, Philip; Rodigas, Timothy J. [Steward Observatory, The University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States)] [Steward Observatory, The University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States); Kopon, Derek [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)] [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Puglisi, Alfio; Esposito, Simone; Riccardi, Armando; Pinna, Enrico; Xompero, Marco; Briguglio, Runa [INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)] [INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)

2013-09-20

221

T'ao-t'ieh, a motif of Chinese funerary art as the iconographic counterpart of Cinnabar, an alchemical drug.  

PubMed

The agency conferring resurrection is soul or its emblem. The earliest conception of soul is blood. Its Redness penetrates subsoil and is taken up by serpent, from whence arises snake-soul, later snake-god. Blood vapours is the other fraction arising upwards. It becomes wraith bird, later soul bird, and finally bird god. Blood as whole gave snake-god plus bird-god. A winged-cobra became snake-god and bird-god or together, one-as-all. Red Cock was its equivalent. As substance came cinnabar, red like blood and sublimable like soul. Dragon was idealized snake-god. Then Dragon-god plus Bird-god became the equal of blood soul, the magical power. T'ao-t'ieh is Dragon-plus-Bird, snake-god plus bird-god, the equivalent of Cosmic soul. Then cinnabar as the equal of blood soul and T'ao-t'ieh, the emblem of Cosmic soul, each were capable of conferring resurrection and have been interred in Chinese graves. PMID:7183206

Mahdihassan, S

1982-01-01

222

English vowel production by native Mandarin speakers: Influences of AoA, LoR, education, perception, and orthography  

NASA Astrophysics Data System (ADS)

This study investigates relations among several factors that are expected to influence vowel production in second language learning, including AoA, LoR, L2 and general education, L2 perception, and orthography. Vowel production will be examined through duration and formant frequency measurements and listener identification. The results will be analyzed in relation to educational background and language use. Among the educational factors examined are general education level, English education (in their native land and/or New York City), and sound-annotating system experiences in Mandarin (Pinyin or Zhuyin). The language-use factors include AoA, LoR, language spoken at work and at home, and perception of English vowels. The hypotheses addressed include: (1) educational background, language use, and sound-annotating system experiences in Mandarin all influence L2 English speakers perception and production of English vowels; (2) the more accurately an L2 listener discriminates a vowel contrast, the more distinctly he/she produces that contrast.

Bell-Berti, Fredericka; Yu, Yan Helen

2005-09-01

223

A new polymer-based laccase for decolorization of AO7: Long-term storage and mediator reuse.  

PubMed

To address the bottlenecks of laccase-based catalysis, i.e., poor long-term stability and potential secondary pollution caused by synthetic mediator, we fabricated a new biocatalyst (N-PS-Lac) through adsorption of laccase onto polystyrene anion exchangers (N-PS) binding quaternary ammonium groups. After 2-year storage, the residual activity of N-PS-Lac remained as high as 101.7%, while that for native laccase was only 14.6%. Also, N-PS-Lac exhibited improved durability against pH variation and thermal treatment at 60°C. Gaussian curve fitting of FT-IR spectra indicated that laccase conformation of N-PS-Lac was rigidified, possibly because of the host geometric restriction and the host-laccase electrostatic attraction. A two-step method, i.e., adsorption of an azo dye AO7 by N-PS and then ectopic degradation by the immobilized laccase, was proposed to reuse the mediator HOBT for seven cyclic runs, where N-PS-Lac kept the constant decolorization efficiency. AO7 solution was detoxified completely after decolorization by the two-step method. PMID:24862000

Zhang, Xiaolin; Pan, Bingcai; Wu, Bing; Zhang, Weiming; Lv, Lu

2014-07-01

224

Use of a single 2.0-mm locking AO reconstruction titanium plate in linear, non-comminuted, mandible fractures  

PubMed Central

Purpose: The aim of the following study is to prospectively evaluate the use of a single Arbeitsgemeinschaft für Osteosynthesefragen (AO) 2.0-mm locking reconstruction plate for linear non-comminuted mandibular fractures without the use of a second plate. Materials and Methods: This study consisted of a sample of 10 patients who reported to the department with fractures of the mandible and were treated over a period of 24 months from November 2010 to November 2012. Out of these, there were 8 male patients and 2 female patients. There were four cases of isolated parasymphysis fractures, 1 of the case had a parasymphysis fracture associated with subcondylar fracture, 4 had a body fracture and 2 had a symphysis fracture. Results: All patients had satisfactory fracture reduction and a successful treatment outcome without major complications. Only one patient (10%) developed minor complications. Conclusion: The study has demonstrated that treating linear non-comminuted mandibular fractures with a single AO 2.0-mm locking reconstruction plate provides excellent stability at the fracture site which in turn leads to sound bone healing and early functional rehabilitation.

Parmar, Babu S.; Makwana, Kalpesh G.; Patel, Aditi M.; Tandel, Ramanuj C.; Shah, Jay

2014-01-01

225

Combination of the AO-Magerl and load-sharing classifications for the management of thoracolumbar burst fractures.  

PubMed

The AO-Magerl classification is widely accepted for the appropriate management of patients with thoracolumbar burst fractures; however, it fails to assess the ability of the injured spine to withstand compressive loading and cannot predict instrumentation failure after short-segment posterior fixation. The load-sharing classification depends on the degree of comminution and apposition of bony fragments.We retrospectively classified according to both classifications 100 consecutive patients with 1-level thoracolumbar burst fractures treated nonoperatively or operatively within a 7-year period. Sixty neurologically intact patients (60%) were treated nonoperatively, 15 (15%) had short posterior instrumentation, 15 (15%) had short anterior instrumentation, and 10 (10%) had combined short posterior instrumentation and anterior strut grafting. Twenty-five of the 40 (60%) surgically treated patients had neurological impairment on admission. Clinical outcome was assessed using a pain and working ability scale. Mean follow-up was 52 months (range, 24-70 months). Function was satisfactory in 55 (92%) nonoperatively treated patients and in 33 (83%) surgically treated patients. Neurological improvement by American Spinal Injury Association (ASIA) grade was observed in patients with incomplete paraplegia (70% of neurologically impaired patients) who were treated operatively.The combination of AO-Magerl and load-sharing classifications provides for accurate selection of treatment, surgical approach, and length of instrumentation, and can guide the decision for additional anterior surgery. PMID:20349867

Katonis, Pavlos; Pasku, Dritan; Alpantaki, Kalliopi; Mavrogenis, Andreas F; Korres, Demetrios S; Sapkas, George S; Papagelopoulos, Panayiotis J

2010-03-01

226

Time and frequency evolution of radio spectrum of the BL Lacertae type object AO 0235+16  

NASA Astrophysics Data System (ADS)

In this work we present investigations of multifrequency spectra of BL Lacertae type object called AO 0235+16. All data had been observed by RATAN-600 radiotelescope from 2006 to 2011. Variations and spectrum parameters such as a peak frequency (?0), FWHM, etc. had been studied. Also Shklovsky-Van der Laan model for variable extragalactic radio sources was programmed and applied to compare our observed data and theoretical values. Comparison revealed that calculations based on Shklovsky-Van der Laan model are in good agreement with observed data (Pearson correlation coefficient close to 1) and they clear up physical processes that proceed in object during its evolution. Differences between model and experiment caused mainly by limitation to the magnetic field and its uniformity, particles concentration and source structure. Nowadays we know that the best agreement achieves by taking account of heterogeneous structure and assuming continuously acceleration of particles during expansion.

Mufakharov, T.

2012-05-01

227

Characterization of OCam and CCD220: the fastest and most sensitive camera to date for AO wavefront sensing  

NASA Astrophysics Data System (ADS)

For the first time, sub-electron read noise has been achieved with a camera suitable for astronomical wavefront-sensing (WFS) applications. The OCam system has demonstrated this performance at 1300 Hz frame rate and with 240×240-pixel frame rate. ESO and JRA2 OPTICON2 have jointly funded e2v technologies to develop a custom CCD for Adaptive Optics (AO) wavefront sensing applications. The device, called CCD220, is a compact Peltier-cooled 240×240 pixel frame-transfer 8-output back-illuminated sensor using the EMCCD technology. This paper demonstrates sub-electron read noise at frame rates from 25 Hz to 1300 Hz and dark current lower than 0.01 e-/pixel/frame. It reports on the comprehensive, quantitative performance characterization of OCam and the CCD220 such as readout noise, dark current, multiplication gain, quantum efficiency, charge transfer efficiency... OCam includes a low noise preamplifier stage, a digital board to generate the clocks and a microcontroller. The data acquisition system includes a user friendly timer file editor to generate any type of clocking scheme. A second version of OCam, called OCam2, was designed offering enhanced performances, a completely sealed camera package and an additional Peltier stage to facilitate operation on a telescope or environmentally rugged applications. OCam2 offers two types of built-in data link to the Real Time Computer: the CameraLink industry standard interface and various fiber link options like the sFPDP interface. OCam2 includes also a modified mechanical design to ease the integration of microlens arrays for use of this camera in all types of wavefront sensing AO system. The front cover of OCam2 can be customized to include a microlens exchange mechanism.

Feautrier, Philippe; Gach, Jean-Luc; Balard, Philippe; Guillaume, Christian; Downing, Mark; Hubin, Norbert; Stadler, Eric; Magnard, Yves; Skegg, Michael; Robbins, Mark; Denney, Sandy; Suske, Wolfgang; Jorden, Paul; Wheeler, Patrick; Pool, Peter; Bell, Ray; Burt, David; Davies, Ian; Reyes, Javier; Meyer, Manfred; Baade, Dietrich; Kasper, Markus; Arsenault, Robin; Fusco, Thierry; Diaz-Garcia, José Javier

2010-07-01

228

Use of the AO veterinary mini 'T'-plate for stabilisation of distal radius and ulna fractures in toy breed dogs.  

PubMed

The use of the AO (Arbeitsgemeinschaft für Osteosynthesefragen) veterinary mini 'T'-plate for stabilisation of distal radius and ulna fractures in toy breed dogs was evaluated in a retrospective study. All of the 14 dogs in the study weighed 3.5 kg or less. The AO mini 'T'-plate was used as the final means of fixation in all cases. It was used as the primary form of stabilisation in ten dogs, and in four dogs it was used at revision surgery. In all cases, of the fractures healed. Return to function was graded 'as excellent' in six cases, 'good' in four and 'fair' in two. Two dogs were lost to long-term follow up. It was concluded that the AO veterinary mini 'T'-plate is a suitable choice of implant for stabilisation of distal radius and ulna fractures in toy breed dogs, especially when the distal fragment is very small. PMID:16594212

Hamilton, M H; Langley Hobbs, S J

2005-01-01

229

Snow anomaly events from historical documents in eastern China during the past two millennia and implication for low-frequency variability of AO/NAO and PDO  

NASA Astrophysics Data System (ADS)

Models and instrumental data indicate that the spatial and temporal variations of snow cover are significantly related to atmospheric circulation (e.g. the AO/NAO). Here, we present historical snow anomaly events during the past two millennia that provide a unique temporal window to studying long-term AO/NAO, a prominent phenomenon in wintertime. Direct descriptions such as ``no snow during the winter'' and ``pray God for snow'' are interpreted as convincing evidence for snow anomalies. The variations of positive/negative snow abnormal events show clear decadal to century variations during the past two millennia. Based on the previous instrumental research and comparison with other reconstruction data, we suggest the Index of Abnormal Snow (IAS) may be an AO-like atmospheric variability. The winter during the Medieval Warm Period (MWP) (AD 900-1300) might be strongly influenced by a predominantly positive AO with less snow condition, whereas the Little Ice Age (LIA) (AD 1300-1900) by negative AO concomitant with heavier snowfalls in East Asia. Our data show that a warm climate period (the MWP)/a cold period (the LIA) can be perturbed by a cold spell/a warm spell which are linked with a change in atmospheric circulation. Low-frequency variability of snow records may be intrinsic to the natural climate system. Although the dynamic mechanisms linking snow anomalies with atmospheric circulation (the AO/NAO, the PDO) is unclear on the decadal to century time scales, Pacific Ocean may play an important role in regulating atmospheric circulations since the IAS is highly correlated with the reconstruction of PDO.

Chu, Guoqiang; Sun, Qing; Wang, Xiaohua; Sun, Junying

2008-07-01

230

SRT Evaluation of AIRS Version-6.02 and Version-6.02 AIRS Only (6.02 AO) Products  

NASA Technical Reports Server (NTRS)

Version-6 contains a number of significant improvements over Version-5. This report compares Version-6 products resulting from the advances listed below to those from Version-5. 1. Improved methodology to determine skin temperature (T(sub s)) and spectral emissivity (Epsilon(sub v)). 2. Use of Neural-net start-up state. 3. Improvements which decrease the spurious negative Version-5 trend in tropospheric temperatures. 4. Improved QC methodology. Version-6 uses separate QC thresholds optimized for Data Assimilation (QC=0) and Climate applications (QC=0,1) respectively. 5. Channel-by-channel clear-column radiances R-hat(sub tau) QC flags. 6. Improved cloud parameter retrieval algorithm. 7. Improved OLR RTA. Our evaluation compared V6.02 and V6.02 AIRS Only (V6.02 AO) Quality Controlled products with those of Version-5.0. In particular we evaluated surface skin temperature T(sub s), surface spectral emissivity Epsilon(sub v), temperature profile T(p), water vapor profile q(p), OLR, OLR(sub CLR), effective cloud fraction alpha-Epsilon, and cloud cleared radiances R-hat(sub tau) . We conducted two types of evaluations. The first compared results on 7 focus days to collocated ECMWF truth. The seven focus days are: September 6, 2002; January 25, 2003; September 29, 2004; August 5, 2005; February 24, 2007; August 10, 2007; and May 30, 2010. In these evaluations, we show results for T(sub s), Epsilon(sub v), T(p), and q(p) in terms of yields, and RMS differences and biases with regard to ECMWF. We also show yield trends as well as bias trends of these quantities relative to ECMWF truth. We also show yields and accuracy of channel by channel QC d values of R-hat(sub tau) for V6.02 and V6.02 AO. Version-5 did not contain channel by channel QC d values of R-hat(sub tau). In the second type of evaluation, we compared V6.03 monthly mean Level-3 products to those of Version-5.0, for four different months: January, April, July, and October; in 3 different years 2003, 2007, and 2011. In particular, we compared V6.03 and V5.0 trends of T(p), q(p), alpha-Epsilon, OLR, and OLR(sub CLR) computed based on results for these 12 time periods

Susskind, Joel; Iredell, Lena; Molnar, Gyula; Blaisdell, John

2012-01-01

231

Monitoring Io volcanic activity using the Keck AO system: 2-5?m sunlit and eclipse observations  

NASA Astrophysics Data System (ADS)

Galileo provided us with spectacular images of the volcanically active Io moon over the last 7 years, but we understand little about the physical processes occurring on this moon. Groundbased monitoring programs help characterize the long time evolution of Io's volcanic activity, such as the frequency, spatial distribution and temperature of hot spots and outbursts. Our group started a monitoring program of Io's volcanic activity using the Keck II Adaptive Optics (AO) system and its recently installed near-infrared camera NIRC2. Here we report groundbased observations of Io conducted in December 2001 (UT), at 0.05" resolution (120-140 km on Io) in K', i.e., ~4 times better than HST and than global Galileo NIMS images. Our 1-5 micron data enable us to determine the temperature of individual hot spots, a key parameter for geophysical/volcanic flow models. We will present: i) Io in reflected sunlight in K', L', and M bands. We used Io itself as reference source for the wavefront sensor of the AO system. Our L and M-band images show both reflected sunlight and thermal emission from volcanic hot spots. The contrast of images is enhanced using the MISTRAL deconvolution algorithme. The 12 images taken on 10 days provides a complete survey of Io surface during one full rotation. 26 active hot spots were detected on the entire surface in L band (3.8?m), approximatively three times more in M band (4.7?m). One active hot spot is seen in K band (2.2?m) in the Pele area. A study of individual hot spot (temperature, emission area, nature) will be presented. ii) Io in eclipse. While Io is in Jupiter's shadow, it is invisible to the wavefront sensor, but its hot spots are easily visible in the near-infrared. We imaged Io during the 18 Dec. 2001 eclipse using Ganymede (30" from Io, moving relative to Io at ~0.5"/min) as a reference source. A dozen of faint hot spots are detected at both K' and L', allowing temperature estimates for each of them. Keck Science team is composed of S. Kwok, P. Amico, R. Campbell, F. Chaffee, A. Conrad, A. Contos, B. Goodrich, G. Hill, D. Sprayberry, P. Stomski, P. Wizinowich (W.M. Keck Observatory). This work has been supported in part by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783 and the France-Berkeley Fund.

Marchis, F.; de Pater, I.; Le Mignant, D.; Roe, H. G.; Fusco, T.; Graham, J. R.; Prange, R.; Macintosh, B.

2002-12-01

232

AO — Organization Chart  

Cancer.gov

Skip to Content Home | Investigator Resources | Protocol Development | Initiatives/Programs/Collaborations | Links to More Resources | Funding Opportunities | About CTEP Home | Sitemap | Contact CTEP Search this site Administrative Resource Center

233

Interdecadal variability of the Atlantic meridional overturning circulation in the pre-industrial simulation of HadGEM2-AO  

NASA Astrophysics Data System (ADS)

Atlantic meridional overturning circulation(AMOC) has particularly important roles for the climate system because it, as a part of the ocean circulation, poleward transports the vast amount of heat and brings atmospheric chemicals into deep ocean layers. Here we investigated the temporal and spatial characteristics of AMOC using the 300-yr simulation data from the pre-industrial experiment of HadGEM2-AO. AMOC has the dominant periodicities of the both interannual (2-7 years) and interdecadal (20 and 40 years) time scales. The regression analysis reasonably well captured the relationship between the AMOC intensity and meridional temperature gradient, i.e.,, the enhanced AMOC leads to the surface warming at high latitudes as well as thinning of Arctic sea ice. In addition, the lead-lag correlation analysis indicates that the instability caused by the out of phase between meridional temperature gradient and AMOC strength drive the natural AMOC fluctuation. This study has found that the variation of AMOC intensity can be explained by the only ocean circulation dynamics except the effect of external influences such as the atmosphere-ocean interactions.

Moon, Byung-Kwon; Wie, Jieun; Kim, Ki-Young; Lee, Johan; Boo, Kyung-On; Cho, ChunHo

2014-05-01

234

LDEF (Postflight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tr  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tray H07 The postflight photograph was taken in the KSC SAEF II facility after the experiment was removed from the LDEF. The Space-Based Radar (SBR) Phased-Array Antenna occupies a six (6) inch deep LDEF end corner tray located on the space end of the LDEF. A light tan discoloration is visible on the left and lower flanges of the experiment tray and also on the unpainted aluminum filler to the left of the passive part of the experiment. A darker stain has discolored the lower corners of the tray structure. The SBR Phased-Array Antenna experiment, consisting of an active part in the upper half of the tray and a passive part located in the lower half of the experiment tray, appears to be intact with no apparent physical damage. The black thermal coating on the active part of the experiment appears to have changed from a flat black to a dark gray while the coating on the passive part of the experiment appears less degraded. The exposed Kapton specimen surfaces in both the active and passive parts of the experiment appear to have changed from specular to diffuse from exposure to the space environment.

1990-01-01

235

LDEF (Postflight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tr  

NASA Technical Reports Server (NTRS)

LDEF (Postflight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tray H07 The post landing photograph was taken from the Orbiter's cargo bay access hatch during post landing operations to prepare the Orbiter for the ferry flight from the Dryden Flight Research Center to the Kennedy Space Center. The Space-Based Radar (SBR) Phased-Array Antenna occupies a six (6) inch deep LDEF end corner tray located on the space end of the LDEF. A light tan discoloration can be seen on the left and lower flanges of the experiment tray and a darker stain has discolored the originally white paint dots on the experiment tray clamp blocks. Dark brown stains on the LDEF structure are vis- ible in areas adjacent to the edge of thermal end panels that were designed to facilitate venting of the LDEF interior. The SBR Phased-Array Antenna experiment, consisting of an active part in the left half of the tray and a passive part located in the right half of the experiment tray, appears to be intact with no apparent physical damage. The black thermal coating on the passive part of the experiment appears unchanged while the black thermal coating on the active part of the experiment appears dark gray. The passive experiment Kapton specimen surfaces appear to have changed from specular to diffuse after exposure to the space environment.

1990-01-01

236

LDEF (Flight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tray H  

NASA Technical Reports Server (NTRS)

LDEF (Flight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tray H07 The flight photograph was taken from the Orbiter aft flight deck during the LDEF retrieval. The Space-Based Radar (SBR) Phased-Array Antenna occupies a six (6) inch deep LDEF end corner tray located on the space end of the LDEF. A shadow cast by the Orbiter covers most of the right half of the tray containing the active part of the experiment. Even in the shadow, a light tan discoloration can be seen on the left and lower flanges of the experiment tray and a darker stain has discolored the originally white paint dots on the experiment tray clamp blocks. Dark brown stains on the LDEF structure are visible in areas adjacent to the edge of thermal end panels designed to facilitate venting of the LDEF interior. The SBR Phased-Array Antenna experiment, consisting of an active part in the left half of the tray and a passive part located in the right half of the experiment tray, appears to be intact with no apparent physical damage. The black thermal coating on the passive part of the experiment appears unchanged while the black thermal coating on the active part of the experiment appears a dark gray. The passive experiment Kapton specimen surfaces appear to have changed from specular to diffuse when exposed to the space environment.

1990-01-01

237

[Clinical results of primary intramedullary osteosynthesis with the unreamed AO/ASIF tibial intramedullary nail of open tibial shaft fractures].  

PubMed

From 04/91 to 06/96 sixty-nine open fractures of the tibia were primarily treated on the day of the accident with unreamed nailing (UTN, Synthese). The distributions of fracture type according to the AO classification and of soft tissue injury according to Gustilo were as follows: fracture type: A: 28%, B: 52%, C: 20%; soft tissue injury: I: 30%, II: 28%, IIIA: 12%, IIIB: 12%, IIIC: 6%. Of the 65 fractures assessed 46 (71%) healed within 18 weeks without secondary intervention. There was delayed healing in three fractures requiring secondary conversion to reamed nailing. Eight fractures (12%) developed pseudarthrosis of which five (8%) healed uneventfully. Deep infections was manifest in four fractures (6%). Three of these infections developed after secondary intervention to treat pseudarthrosis. Seven of the eight pseudarthroses and three of the four infections healed eventually. Revision procedures were necessary in 11 patients (17%) to deal with disturbed fracture healing or infection (10 reamed nailing procedures, three cancellous bone grafts, and one of each of the following: sequestrectomy, fibular osteotomy, plate fixation, external fixator, monorail procedure). The results show that the same good infection rates were achieved for the UTN as for the external fixator. The advantages of the UTN are, however, a lesser need for secondary intervention and greater patient comfort. Therefore, we find the UTN to be a good alternative to the external fixator in the treatment of open fractures with severe soft tissue damage. PMID:9865165

Müller, C A; Dietrich, M; Morakis, P; Pfister, U

1998-11-01

238

MULTI-WAVELENGTH OBSERVATIONS OF BLAZAR AO 0235+164 IN THE 2008-2009 FLARING STATE  

SciTech Connect

The blazar AO 0235+164 (z = 0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to {gamma}-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the {gamma}-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R{sub g}. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus.

Ackermann, M. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Buehler, R.; Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Ballet, J.; Casandjian, J. M. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Caliandro, G. A. [Institut de Ciencies de l'Espai (IEEE-CSIC), Campus UAB, 08193 Barcelona (Spain); Caraveo, P. A., E-mail: eduardo@slac.stanford.edu, E-mail: madejski@slac.stanford.edu, E-mail: fabio.gargano@ba.infn.it, E-mail: silvia.raino@ba.infn.it, E-mail: lreyes04@calpoly.edu, E-mail: knalew@colorado.edu, E-mail: sikora@camk.edu.pl [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Collaboration: Fermi-LAT Collaboration; GASP-WEBT consortium; F-GAMMA; Iram-PdBI; Kanata; RXTE; SMARTS; Swift-XRT; and others

2012-06-01

239

Microstructure and fission gas bubbles in irradiated mixed carbide fuels at 2 to 11 a/o burnup  

NASA Astrophysics Data System (ADS)

An analysis of the defect structure and of small fission gas bubbles has been performed on mixed carbide fuels with burn-ups between 1.8 and 11 a/o by transmission electron microscopy (TEM). A complex defect structure consisting of dislocations, loops and at least 3 types of solid fission product precipitates was observed. Na-bonded carbides develop predominantly a dislocation network increasing in density with burn-up whereas He-bonded carbides showed mainly a corresponding network of crystallographic needle precipitates. Locally the nucleation and growth of small fission gas bubbles with 1 to 20 nm diameters (bubble population P 1) is closely related to their dislocation or needle environment, larger bubbles with diameters 30 to 50 nm appear to be mostly associated with platelike precipitates or dislocation boundaries. The local swelling contribution ? 1 of bubble population P 1 is ? 0.5% and its fission gas content G 1 is 4 to 5% of the total amount of gas created over the whole burn-up range investigated.

Ray, I. L. F.; Blank, H.

1984-05-01

240

Volcanic activity of Io observed in December 2001 with the Keck AO system: 2-5mu m sunlit and eclipse observations  

Microsoft Academic Search

Volcanically active Io remains a mysterious and intriguing moon, despite numerous spacecraft flybys. Groundbased monitoring programs help characterize the time evolution of Io's volcanic activity, such as the frequency, spatial distribution and temperature of hot spots and outbursts. The satellite was observed intensively in December 2001 with the Keck II Adaptive Optics (AO) system and its recently installed near-infrared camera

F. Marchis; I. de Pater; D. Le Mignant; H. Roe; T. Fusco; J. R. Graham; R. Prange; B. Macintosh

2002-01-01

241

Since When or How Often? Dissociating the Roles of Age of Acquisition (AoA) and Lexical Frequency in Early Visual Word Processing  

ERIC Educational Resources Information Center

The aim of the study was to investigate the effect of both word age of acquisition (AoA) and frequency of occurrence on the timing and topographical distribution of ERP components. The processing of early- versus late-acquired words was compared with that of high-frequency versus low-frequency words. Participants were asked to perform an…

Adorni, Roberta; Manfredi, Mirella; Proverbio, Alice Mado

2013-01-01

242

Reconstrução do ligamento cruzado anterior: impacto do desempenho muscular e funcional no retorno ao mesmo nível de atividade pré-lesão  

Microsoft Academic Search

RESUMO Introdução: A reconstrução do LCA objetiva restabelecer a biome- cânica e minimizar a instabilidade do joelho. Objetivo: comparar performance muscular, funcional e frouxidão ligamentar, entre voluntários que retornaram ao mesmo nível de atividade pré-lesão e aqueles que não retornaram, após a reconstrução ligamentar. Métodos: 25 homens, operados pelo mesmo cirurgião, com o ligamento patelar, via artroscopia e mais de

Lygia Paccini Lustosa; Sérgio Teixeira da Fonseca; Marco Antônio Percope de Andrade

2007-01-01

243

O PROCESSO DECISÓRIO DE IMPLANTAÇÃO DE ESTRUTURA DE ARMAZENAGEM DE SOJA AO NÍVEL DE PROPRIEDADE RURAL NA REGIÃO DE SANTO ÂNGELO\\/RS  

Microsoft Academic Search

Considerando-se que existe um déficit na capacidade estática de armazenamento de grãos no Brasil, aliado a baixa margem de rentabilidade auferida pelos produtores de commodities agrícolas, notadamente a soja, bem como o fato de que a armazenagem em nível de propriedade rural pode vir a se constituir em um diferencial positivo ao produtor no momento da comercialização desta oleaginosa, buscou-se

Alberto Silva Dutra; Joao Armando Dessimon Machado; Regis Rathmann

2008-01-01

244

ADAPTABILIDADE E ESTABILIDADE DE REAÇÃO DE GENÓTIPOS DE SOJA AO OÍDIO, EM CASA DE VEGETAÇÃO ADAPTABILITY AND STABILITY OF REACTION OF SOYBEAN GENOTYPES TO POWDERY MILDEW, IN GREENHOUSE  

Microsoft Academic Search

RESUMO: O objetivo deste trabalho foi estudar o comportamento de genótipos de soja em relação ao oídio, por meio de estudos de adaptabilidade e de estabilidade, em casa de vegetação, durante cinco épocas de avaliação. O delineamento experimental foi inteiramente casualizado, disposto em parcelas subdivididas, com 15 tratamentos e três tipos de controle (parcial, total e sem controle) representando as

Derval Gomes PEREIRA; Tuneo SEDIYAMA; Cosme Damião CRUZ; Múcio Silva REIS

245

Molecular dynamics evidence for alkali-metal rattling in the ?-pyrochlores, AOs2O6 (A = K, Rb, Cs).  

PubMed

We have used ab initio molecular dynamics simulations validated against inelastic neutron scattering data to study alkali-metal dynamics in the ?-pyrochlore osmates AOs2O6 (A=K, Rb, Cs) at 300 K to gain insight into the microscopic nature of rattling dynamics in these materials. Our results provide new evidence at the microscopic level for rattling dynamics: (1) the elemental magnitude spectra calculated from the MD show a striking dominance by the alkali metals at low energies indicating weak coupling to the cage, (2) the atomic root-mean-square displacements for the alkali metals are significantly larger than for the other atoms, e.g., 25% and 150% larger than O and Os, respectively, in KOs2O6, and (3) motions of the alkali metals are weakly correlated to the dynamics in their immediate environment, e.g. K in KOs2O6 is 6 times less sensitive to its local environment than Os, indicating weak bonding of the K. There is broadening of the elemental spectra of the alkali metals from Cs to K corresponding to a similar broadening of the local potential around these atoms as determined from potential of mean-force calculations. This feature of the spectra is partly explained by the well-known increase in the relative cage volume with decreasing atomic size of the alkali metal. We find that for the smallest rattler in this series (K) the larger relative cage volume allows this atom freedom to explore a large space inside the cage leading to vibration at a broader range of frequencies, hence a broader spectrum. Thus, since K is considered the best rattler in this series, these findings suggest that a significant feature of a good rattler is the ability to vibrate at several different but closely spaced frequencies. PMID:24172693

Shoko, E; Peterson, V K; Kearley, G J

2013-11-27

246

Molecular dynamics evidence for alkali-metal rattling in the ?-pyrochlores, AOs2O6 (A = K, Rb, Cs)  

NASA Astrophysics Data System (ADS)

We have used ab initio molecular dynamics simulations validated against inelastic neutron scattering data to study alkali-metal dynamics in the ?-pyrochlore osmates AOs2O6 (A=K, Rb, Cs) at 300 K to gain insight into the microscopic nature of rattling dynamics in these materials. Our results provide new evidence at the microscopic level for rattling dynamics: (1) the elemental magnitude spectra calculated from the MD show a striking dominance by the alkali metals at low energies indicating weak coupling to the cage, (2) the atomic root-mean-square displacements for the alkali metals are significantly larger than for the other atoms, e.g., 25% and 150% larger than O and Os, respectively, in KOs2O6, and (3) motions of the alkali metals are weakly correlated to the dynamics in their immediate environment, e.g. K in KOs2O6 is 6 times less sensitive to its local environment than Os, indicating weak bonding of the K. There is broadening of the elemental spectra of the alkali metals from Cs to K corresponding to a similar broadening of the local potential around these atoms as determined from potential of mean-force calculations. This feature of the spectra is partly explained by the well-known increase in the relative cage volume with decreasing atomic size of the alkali metal. We find that for the smallest rattler in this series (K) the larger relative cage volume allows this atom freedom to explore a large space inside the cage leading to vibration at a broader range of frequencies, hence a broader spectrum. Thus, since K is considered the best rattler in this series, these findings suggest that a significant feature of a good rattler is the ability to vibrate at several different but closely spaced frequencies.

Shoko, E.; Peterson, V. K.; Kearley, G. J.

2013-11-01

247

Fluid inclusion characteristics and geological significance of the Xi'ao copper-tin polymetallic deposit in Gejiu, Yunnan Province  

NASA Astrophysics Data System (ADS)

The newly discovered Xi'ao Cu-Sn polymetallic deposit is located in the inner alteration zone of the Laochang-Kafang granite edge in Gejiu, Yunnan Province. The mineralization process of this deposit can be divided into four stages. Cassiterite and chalcopyrite mainly formed at stages II and III, respectively. Fluid inclusions at different stages were studied by petrography, microthermometry, and laser Raman spectrometry. Five fluid inclusion types are observed. Microthermometry results revealed that the ore-forming fluid evolved from high temperature with low to intermediate salinity to low temperature with low salinity. At stage I, the fluid was under near-critical conditions and then separated into coexisting liquid and vapor phases at stage II. Finally, the fluid was boiling and immiscible at stage III. A meteoric fluid mixing process was also observed at this stage. Laser Raman spectra identified CH4 at the skarn and mineralization stages. Combined with other geological features, the deposit was concluded to have formed under a relatively reduced environment. The CO2 component abruptly increased at stage III and probably originated from the exterior. Fluorine may play an important role in mineralization. Cassiterite and chalcopyrite were mainly deposited at 340-440 and 300-400 °C under pressures of 18-50 and 12-36 MPa, respectively. Boiling and immiscibility are probably the main reason for mineral deposition. The deposit of cassiterite and chalcopyrite showed similar salinities but higher temperatures than other mineralization types of deposits in the Gejiu area. This finding indicated that the study deposit probably represents the high-temperature part of the Gejiu mineralization system, thereby benefiting mineral explorations in the Gejiu area.

Liao, Shili; Chen, Shouyu; Deng, Xiaohu; Li, Pei; Zhao, Jiangnan; Liao, Ruanyingzi

2014-01-01

248

Magellan Adaptive Optics First-light Observations of the Exoplanet ? Pic B. I. Direct Imaging in the Far-red Optical with MagAO+VisAO and in the Near-ir with NICI  

NASA Astrophysics Data System (ADS)

We present the first ground-based CCD (? < 1 ?m) image of an extrasolar planet. Using the Magellan Adaptive Optics system's VisAO camera, we detected the extrasolar giant planet ? Pictoris b in Y-short (YS , 0.985 ?m), at a separation of 0.470 ± 0.''010 and a contrast of (1.63 ± 0.49) × 10-5. This detection has a signal-to-noise ratio of 4.1 with an empirically estimated upper limit on false alarm probability of 1.0%. We also present new photometry from the Gemini Near-Infrared Coronagraphic Imager instrument on the Gemini South telescope, in CH 4S,1% (1.58 ?m), KS (2.18 ?m), and K cont (2.27 ?m). A thorough analysis of our photometry combined with previous measurements yields an estimated near-IR spectral type of L2.5 ± 1.5, consistent with previous estimates. We estimate log (L bol/L ?) = -3.86 ± 0.04, which is consistent with prior estimates for ? Pic b and with field early-L brown dwarfs (BDs). This yields a hot-start mass estimate of 11.9 ± 0.7 M Jup for an age of 21 ± 4 Myr, with an upper limit below the deuterium burning mass. Our L bol-based hot-start estimate for temperature is T eff = 1643 ± 32 K (not including model-dependent uncertainty). Due to the large corresponding model-derived radius of R = 1.43 ± 0.02 R Jup, this T eff is ~250 K cooler than would be expected for a field L2.5 BD. Other young, low-gravity (large-radius), ultracool dwarfs and directly imaged EGPs also have lower effective temperatures than are implied by their spectral types. However, such objects tend to be anomalously red in the near-IR compared to field BDs. In contrast, ? Pic b has near-IR colors more typical of an early-L dwarf despite its lower inferred temperature.

Males, Jared R.; Close, Laird M.; Morzinski, Katie M.; Wahhaj, Zahed; Liu, Michael C.; Skemer, Andrew J.; Kopon, Derek; Follette, Katherine B.; Puglisi, Alfio; Esposito, Simone; Riccardi, Armando; Pinna, Enrico; Xompero, Marco; Briguglio, Runa; Biller, Beth A.; Nielsen, Eric L.; Hinz, Philip M.; Rodigas, Timothy J.; Hayward, Thomas L.; Chun, Mark; Ftaclas, Christ; Toomey, Douglas W.; Wu, Ya-Lin

2014-05-01

249

The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system  

NASA Astrophysics Data System (ADS)

We are commissioning the Laser Guide Star Adaptive Optics (LGS/AO188) system for Subaru Telescope at Hawaii, Mauna Kea. This system utilizes a combination of an all-solid-state mode-locked sum-frequency generation (SFG) laser (1.7GHz-bandwidth, 0.7ns-pulse width) as a light source and single-mode optical fiber for beam transference. However, optical fibers induce nonlinear scattering effects, such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), beyond certain threshold levels in high-power lasers. We measured the laser transmission characteristics of a photonic crystal fiber (PCF) whose mode field diameter (MFD) was 11 ? m, and a step index fiber (SIF) cable whose MFD was 4.2 ? m to evaluate the threshold levels for non-linear effects. We observed SRS in the 200-m-long SIF when we input 1.3W. The material losses of them were 10db/km and 6.4dB/km, respectively. However, SRS and SBS were not induced in the 200-m-long PCF, even for an input power of 5.3W. As a result, we estimated the threshold of SRS to be 33W for the 35-m-long PCF designed for the Subaru LGSAO system. Other than SRS and SBS, we found self phase modulation (SPM) in our PCF. SPM makes the spectrum of the laser beam broaden and it causes less efficiency of generating bright LGS. We measured width of the spectrum by spectrum analyzer. As the result, we found it was 9.1GHz of full width half maximum (FWHM) in comparison with the original FWHM of our laser spectrum, 2.1GHz. This shows 70% of the laser energy for brightening the LGS was lost. We also measured the brightness of the LGS and evaluated its relationship with wavelength of the laser. The LGS's brightness showed a peculiar tendency that did not be extinguish even though the wavelength has varied about 2pm. The tendency was not shown with the experiment using sodium gas cell. Therefore, it may be concerned the environment of the sodium layer in the mesosphere.

Ito, M.; Hayano, Y.; Saito, Y.; Takami, H.; Iye, M.; Hattori, M.; Oya, S.; Watanabe, M.; Akagawa, K.; Colley, S. A.; Golota, T. I.; Guyon, O.

2010-07-01

250

Time Differential Electrical Resistivity for Water Resource Assessment: A Case Study in Cura‡ao, Netherlands Antilles  

NASA Astrophysics Data System (ADS)

A method of groundwater prospecting is presented that capitalizes on changes in electrical resistivity arising from annual variability in subsurface fluid flow. According to Archie's Law, effective resistivity is a function of pore fluid resistivity, saturation, and porosity. For competent Earth materials, short-term temporal changes in near-surface porosity are negligible because changes in effective pressure are small with respect to the bulk moduli of the materials. Therefore, annual variability in effective resistivity is dependent only on fluid flow via changes in saturation and, to a lesser extent, pore fluid resistivity. Aquifer detection is but the first step; thereafter, it is necessary to estimate permeability, capacity, and, importantly, sustainability. Time differential resistivity is well matched to the task because it detects prospective aquifers and also illuminates their natural hydrodynamics. Explicitly, this method captures an undeveloped aquifer's seasonal volumetric variability, which is important as engineers reconcile monthly demand with monthly supply. The best scenario would be to detect a capacious, intermediate-resistivity (high pore fluid resistivity and high porosity) zone that is invariant from season to season (clays and ore bodies excepted). Less desirable, but still manageable, is the case where a large, porous formation undergoes significant seasonal resistivity variation; it behaves as a subterranean river with little lag-time between meteoric water input and groundwater throughput; carefully timed extraction and storage would be required in this case. A suite of thirty-eight electrical resistivity soundings were collected from the wet and dry seasons at Plantages PortoMari, an ecotourist plantation on the semiarid island of Cura‡ao, N.A. The data were analyzed with special attention paid to wet-to-dry season resistivity ratios. The results suggest two possible courses of action. (1) A hypothetical limestone terrace was detected whose estimated minimum water volume fluctuates between approximately 1200m3 and 2300m3; this terrace may be tapped with several boreholes descending to an elevation of 25m ASL. (2) A shallow subsurface dam and extraction fence (10m BGS) might be installed where the watershed corridor converges onto a flat plain whose surficial lithology is comprised of poorly sorted alluvia atop an impermeable clayey unit. Both extraction scenarios require storage facilities, as neither hydrogeologic setting indicates a persistent aquifer.

Coles, D.; Vichabian, Y.; Sogade, J.; Spiertz, P.; Morgan, F. D.

2003-12-01

251

Characterization of AB74, ARS, AO7, and DR28 During the Electro-Fenton Process by Using Three-Dimensional Excitation and Emission Matrix Fluorescence Spectroscopy  

NASA Astrophysics Data System (ADS)

The characteristics of Acid Blue 74 (AB74), Alizarin Red S (ARS), Acid Orange 7 (AO7) and Direct Red 28 (DR28) were investigated by using EEM fluorescence spectroscopy and UV-vis spectroscopy. The results suggest that the azo and anthraquinone dyes can be quickly distinguished from other dyes (such as AB74) according to their different total fluorescence intensity. During the decolorization process by the electro-Fenton technique, the total fluorescence intensity of the four dyes all would increase to their maximum value, but the fluorescence intensity increase in multiples of 12 (ARS), 61 (AO7), and 13 (DR28) times was much higher than that of AB74 (3 times). Furthermore, the different fluorescence intensities of the four dyes in the electro-Fenton process resulted mainly from their different chemical structure characteristics. Additionally, EEM spectroscopy can support much more information about the chemical structure characteristics of the dyes than the conventional UV-vis spectroscopy.

Zhang, Y. H.; Lai, B.; Zhou, Y. X.; Wang, J. L.; Yang, P.

2013-11-01

252

Diode-pumped doubly Q-switched mode-locked YVO 4\\/Nd:YVO 4 laser with AO and GaAs saturable absorber  

Microsoft Academic Search

By using both acousto-optic (AO) modulator and GaAs saturable absorber, a diode-pumped doubly Q-switched and mode-locked (QML) YVO4\\/Nd:YVO4 laser is presented. The average output power and the pulse width of the Q-switched envelope have been measured. The Q-switch pulse energy of the doubly QML laser are higher than that only with GaAs. The stability of the QML laser with the

Yan Zhang; Shengzhi Zhao; Dechun Li; Kejian Yang; Guiqiu Li; Gang Zhang; Kang Cheng

2010-01-01

253

Start-up of a two-stage bioaugmented anoxic–oxic (A\\/O) biofilm process treating petrochemical wastewater under different DO concentrations  

Microsoft Academic Search

The traditional two-stage anoxic–oxic (A\\/O) activated sludge process might be inefficient in pollutants removal and could not ensure the effluent quality. By installing polyurethane foams as carriers and inoculating specialized bacteria in the oxic compartments, the activated sludge systems could be transformed into bioaugmented biofilm processes to enhance the removal efficiency to recalcitrant pollutants. Optimal environment should be provided for

Jingbo Guo; Fang Ma; Chein-Chi Chang; Di Cui; Li Wang; Jixian Yang; Liang Wang

2009-01-01

254

Effect on the Solubility, Wettability, and Dispersibility of the ??CD?Deltamethrin Inclusion Complex in Presence of Mixed Surfactant (C14MEA\\/AOS) Blend  

Microsoft Academic Search

An inclusion complex formation using ??cyclodextrin (??CD) as the host molecule and deltamethrin as guest molecule was a first step towards improvement in conventional insecticide formulations. ??CD?deltamethrin inclusion complex formation in the absence and presence of the nonionic myrisitic acid monoethanolamide (C14MEA)\\/anionic ??olefin sulfonate C12?C14 (AOS) mixed surfactant system was comparatively studied. The co?evaporation method was used for complex formation,

Rakesh K. Nair; Mahesh M. Kadam; M. R. Sawant

2006-01-01

255

PALMAR PLATE FIXATION OF AO TYPE C2 FRACTURE OF DISTAL RADIUS USING A LOCKING COMPRESSION PLATE – A BIOMECHANICAL STUDY IN A CADAVERIC MODEL  

Microsoft Academic Search

The stability of palmar plate fixation using a locking compression T-plate was compared with that of a conventional palmar T-plate and a dorsal T-plate in a cadaveric model of an AO type C2 fracture of distal radius. The wrist axial load transmission through the radius was tested for each fixation. The results show that, under 100N axial load, the palmar

F. LEUNG; L. ZHU; H. HO; W. W. LU; S. P. CHOW

2003-01-01

256

Minority Graduate Fellowship Awards Program for Fiscal Year 1996  

NSF Publications Database

... UNIV OF ARIZONA, UNIV OF Hoffman, Laura Lopez ECOLOGY PRINCETON UNIV/NJ STANFORD UNIV/CA Hurtado ... MICHIGAN, UNIV OF Lopez, Jorge Eduardo ECOLOGY CALIF, U-DAVIS CHICAGO, UNIV OF/IL Lozano, Adriana ...

257

Identification of a copper-responsive promoter and development of a copper biosensor in the soil bacterium Achromobacter sp. AO22.  

PubMed

A number of human activities result in environmental contamination with copper compounds that can cause severe detrimental effects on the ecosystem as well as human health. The physico-chemical methods of metal detection have limitations such as inability to distinguish between total versus bio-available metals and differences in metal uptake in different organisms. The heavy metal resistance-encoding genetic systems of certain bacteria provide critical tools for development of biosensors for these purposes. This study reports a copper biosensor utilizing the cop operon of the heavy metal resistant bacterial isolate, Achromobacter sp. AO22, isolated from a contaminated site in Australia. A section located between the divergently transcribed putative response regulator gene copR and multicopper oxidase gene copA that included a palindromic cop box was identified as a copper-responsive promoter using a lacZ reporter construct, pCOPRP, in E. coli. The expression was found to be enhanced by inclusion of copR. Another engineered strain, AO22(pCOPRP), showed stronger induction, and the lacZ expression in both backgrounds was enhanced significantly (250-400 fold) by copper but minimally by other metals. The construct in Achromobacter sp. AO22 thus has a high potential as biosensor for detecting copper bioavailability (hence potential toxicity) in a soil bacterial background, while the construct in E. coli is ideal for laboratory-based testing. PMID:22806045

Ng, Shee Ping; Palombo, Enzo A; Bhave, Mrinal

2012-05-01

258

Technetium(V) oxo complexes of substituted propylene diamine dioxime (PnAO) ligands: water-dependent interconversion between syn and anti isomers.  

PubMed

99mTc and (99)Tc complexes of PnAO (propylene diamine dioxime) ligands monosubstituted in the 6-position [PnAO-6-R] were prepared and studied. Ligands substituted with an alkyl group or with no substituent (R = H, CH(3), or CH(2)CH(CH(3))(2)), gave only one Tc complex. However, for several other nonalkyl substituents (R = COOCH(3), OH, OCH(3), OCH(2)CH(3), F, CN, NHCOCH(3), and NHCOCH(2)CH(3)), two Tc complexes A and B were formed. Products A and B were assigned to the anti and syn TcO(PnAO-6-R) species, respectively, based on (1)H NMR results. X-ray structure analyses supported these assignments. The A (anti) isomer of TcO(PnAO-6-OH) had the chemical formula TcC(13)H(25)N(4)O(4) and crystallized in an orthorhombic system with space group P2(1)2(1)2(1) and Z = 4; a = 12.744(2) A, b = 13.591(2) A, c = 9.976(2) A. The B (syn) isomer of TcO(PnAO-6-CN) had the chemical formula TcC(14)H(24)N(5)O(3) and was a 1:4 mixture of two monoclinic polymorphs: individual rectangular prisms (space group P2(1)/c, Z = 4) and clusters of intergrown twinned rectangular rods (space group Cc, Z = 8). For the prisms, a = 12.457(1) A, b = 13.932(1) A, c = 10.336(1) A, and for the rods, a = 31.344(5) A, b = 6.993(1) A, c = 21.657(2) A. The syn and anti isomers interconverted in the presence of water; nonequilibrium mixtures of epimers remained unchanged under dry conditions. The HPLC behavior under reversed phase conditions was consistent with on-column interconversion (poor resolution), whereas the two isomers were cleanly resolved under drier normal phase conditions. An oxo inversion mechanism involving trans water attack is proposed for the interconversion process. Water also influenced the position of equilibrium of the two isomers. The syn isomer was stabilized in water relative to the anti isomer. PMID:11421705

Cyr, J E; Nowotnik, D P; Pan, Y; Gougoutas, J Z; Malley, M F; Di Marco, J; Nunn, A D; Linder, K E

2001-07-01

259

Comparison of palmar fixed-angle plate fixation with K-wire fixation of distal radius fractures (AO A2, A3, C1) in elderly patients.  

PubMed

The objective of this prospective, randomized, controlled trial was to compare the results of two operative techniques used for the treatment of unstable distal radius fractures in elderly patients classified as AO types A2, A3, and C1. Patients were treated with either fixed-angle volar plates or K-wires using a combined Kapandji and Willenegger technique. The functional results were determined after 3, 6, and 12 months. We included 40 patients aged over 65 years. Twenty-one patients were treated with plate fixation and 19 with K-wire fixation. The functional results, after 1 year, were nearly the same in both treatment groups, suggesting that either method is suitable for the treatment of unstable distal radius fractures of AO types A2, A3, and C1 in elderly patients. Sixteen of 21 patients with plate fixation and 17 of 19 patients with K-wire fixation present good results as assessed by the Castaing score. The median DASH score was three in both groups after 1 year. The patients with plate fixation were able to resume activities of daily living 4 weeks earlier. The most common complication was an intermediate post-traumatic median nerve irritation. Both methods are suitable for the treatment of elderly patients with unstable distal radius fractures of AO types A2, A3, and C1. If early functional post-operative care is important, palmar fixed-angle plate fixation is an ideal treatment approach. Otherwise, K-wire fixation is an effective, minimally invasive method with comparable clinical results. PMID:23677960

Goehre, F; Otto, W; Schwan, S; Mendel, T; Vergroesen, P P; Lindemann-Sperfeld, L

2014-03-01

260

Backside-illuminated, high-QE, 3e- RoN, fast 700fps, 1760x1680 pixels CMOS imager for AO with highly parallel readout  

NASA Astrophysics Data System (ADS)

The success of the next generation of instruments for 8 to 40-m class telescopes will depend upon improving the image quality (correcting the distortion caused by atmospheric turbulence) by exploiting sophisticated Adaptive Optics (AO) systems. One of the critical components of the AO systems for the E-ELT has been identified as the Laser/Natural Guide Star (LGS/NGS) WaveFront Sensing (WFS) detector. The combination of large format, 1760x1680 pixels to finely sample (84x84 sub-apertures) the wavefront and the spot elongation of laser guide stars, fast frame rate of 700 (up to 1000) frames per second, low read noise (< 3e-), and high QE (> 90%) makes the development of such a device extremely challenging. Design studies by industry concluded that a thinned and backside-illuminated CMOS Imager as the most promising technology. This paper describes the multi-phased development plan that will ensure devices are available on-time for E-ELT first-light AO systems; the different CMOS pixel architectures studied; measured results of technology demonstrators that have validated the CMOS Imager approach; the design explaining the approach of massive parallelism (70,000 ADCs) needed to achieve low noise at high pixel rates of ~3 Gpixel/s ; the 88 channel LVDS data interface; the restriction that stitching (required due to the 5x6cm size) posed on the design and the solutions found to overcome these limitations. Two generations of the CMOS Imager will be built: a pioneering quarter sized device of 880x840 pixels capable of meeting first light needs of the E-ELT called NGSD (Natural Guide Star Detector); followed by the full size device, the LGSD (Laser Guide Star Detector). Funding sources: OPTICON FP6 and FP7 from European Commission and ESO.

Downing, Mark; Kolb, Johann; Baade, Dietrich; Balard, Philippe; Dierickx, Bart; Defernez, Arnaud; Dupont, Benoit; Feautrier, Philippe; Finger, Gert; Fryer, Martin; Gach, Jean-Luc; Guillaume, Christian; Hubin, Norbert; Iwert, Olaf; Jerram, Paul; Jorden, Paul; Pike, Andrew; Pratlong, Jerome; Reyes, Javier; Stadler, Eric; Walker, Andrew

2012-07-01

261

Susceptibility to antibiotics of Vibrio sp. AO1 growing in pure culture or in association with its hydroid host Aglaophenia octodonta (Cnidaria, Hydrozoa).  

PubMed

Vibrio harveyi is the major causal organism of vibriosis, causing potential devastation to diverse ranges of marine invertebrates over a wide geographical area. These microorganisms, however, are phenotypically diverse, and many of the isolates are also resistant to multiple antibiotics. In a previous study, we described a previously unknown association between Vibrio sp. AO1, a luminous bacterium related to the species V. harveyi, and the benthic hydrozoan Aglaophenia octodonta. In this study, we analyzed the susceptibility to antibiotics (ampicillin, streptomycin, tetracycline, or co-trimoxazole = mix of sulfamethoxazole and trimetoprim) of Vibrio sp. AO1 growing in pure culture or in association with its hydroid host by using microcosm experiments. The results of minimum inhibitory concentration (MIC) experiments demonstrated that Vibrio sp. AO1 was highly resistant to ampicillin and streptomycin in pure culture. Nevertheless, these antibiotics, when used at sub-MIC values, significantly reduced the hydroid fluorescence. Co-trimoxazole showed the highest inhibitory effect on fluorescence of A. octodonta. However, in all treatments, the fluorescence was reduced after 48 h, but never disappeared completely around the folds along the hydrocaulus and at the base of the hydrothecae of A. octodonta when the antibiotic was used at concentration completely inhibiting growth in vitro. The apparent discrepancy between the MIC data and the fluorescence patterns may be due to either heterogeneity of the bacterial population in terms of antibiotic susceptibility or specific chemical-physical conditions of the hydroid microenvironment that may decrease the antibiotic susceptibility of the whole population. The latter hypothesis is supported by scanning electron microscope evidence for development of bacterial biofilm on the hydroid surface. On the basis of the results obtained, we infer that A. octodonta might behave as a reservoir of antibiotic multiresistant bacteria, increasing the risk of their transfer into aquaculture farms. PMID:19888625

Stabili, Loredana; Gravili, Cinzia; Boero, Ferdinando; Tredici, Salvatore M; Alifano, Pietro

2010-04-01

262

Kahua A'o: A Learning Foundation: Using Hawaiian Language Newspaper Articles for Place and Culture-based Geoscience Teacher Education and Curriculum Development  

NASA Astrophysics Data System (ADS)

Kahua A'o is a collaborative project funded by the National Science Foundation aimed at developing science curriculum grounded in Hawaiian culture and place-based education. The project team is composed of members who contribute expertise in meteorology, geology, curriculum development, and Hawaiian language. To date, six lessons have been produced, four with a focus in meteorology and two with a focus in geology. The lessons are geared towards the middle school level, but can easily be adapted for other levels. Each lesson combines a scientific topic with relevant Hawaiian language resources. Serving as the main source for resources is the Hawaiian language newspaper archive, which is an online database of 75,000 pages from newspapers that were published between 1834 and 1948. By incorporating Hawaiian language newspaper articles into science lessons, we aim to teach science through culture and show a history of scientific inquiry intrinsic to Hawaiian culture in order to generate more interest in science among Hawai'i students, especially native Hawaiian students, who are underrepresented in scientific fields. Since most of the articles are specific to the Hawaiian Islands, all students will find more relevance with the lesson through place-based education. Kahua A'o lessons are currently being piloted with groups of public school teachers. Bishop Museum is also incorporating elements of the meteorology lessons into their science education curriculum. The goal of Kahua A'o is to become the first of many such interdisciplinary collaborations, especially those that utilize the rich repository of untapped knowledge in the Hawaiian language newspaper archive.

Ellinwood, I.; Stone, K.; Spencer, L.

2012-12-01

263

ExposiÁªo humana ao metilmercœrio em comunidades ribeirinhas da Regiªo do TapajÛs, ParÆ, Brasil Methylmercury human exposure in riverine villages of Tapajos basin, ParÆ State, Brazil  

Microsoft Academic Search

1 Resumo Avaliou-se a exposição humana ao metilmercúrio e ao mercúrio total em comunidades ribeirinhas do rio Tapajós e da região metropolitana de Belém, no Estado do Pará, Brasil, através da determinação de mercúrio total e metilmercúrio em amostras de cabelo nos anos de 1994 e 1995. Observou-se que as concentrações médias de mercúrio total variaram de 2 ± 1µg\\/g-1

Maria da Conceição; Nascimento Pinheiro; Junko Nakanishi; Manoel Quaresma; Bernardo Cardoso; Walter W. Amoras; Masazume Harada; Carlos Magno; Luis F. Vieira; Marilia Brasil Xavier; Denise R. Bacelar

264

Construction of a mouse Aos1-Uba2 chimeric SUMO-E1 enzyme, mAU, and its expression in baculovirus-insect cells.  

PubMed

Small ubiquitin-related modifier (SUMO) is a highly conserved protein that is covalently attached to target proteins. This posttranslational modification, designated SUMOylation, is a major protein-conjugation-driven strategy designed to regulate structure and function of cellular proteins. SUMOylation consists of an enzymatic cascade involving the E1-activating enzyme and the E2-conjugating enzyme. The SUMO-E1 enzyme consists of two subunits, a heterodimer of activation of Smt3p 1 (Aos1) and ubiquitin activating enzyme 2 (Uba2), which resembles the N- and C-terminal halves of ubiquitin E1 (Uba1). Herein, we describe the rational design of a single polypeptide version of SUMO-E1, a chimera of mouse Aos1 and Uba2 subunits, termed mAU, in which the functional domains appear to be arranged in a fashion similar to Uba1. We also describe the construction of a mAU plasmid for expression in a baculovirus-insect cell system and present an in situ SUMOylation assay using the recombinant mAU. Our results showed that mAU has SUMO-E1 activity, thereby indicating that mAU can be expressed in baculovirus-insect cells and represents a suitable source of SUMO-E1. PMID:24637489

Nakayama, Tomofumi; Yuasa, Eri; Kanemaru, Ayumi; Saito, Masayuki; Saitoh, Hisato

2014-03-01

265

The ubiquitin-like protein Smt3p is activated for conjugation to other proteins by an Aos1p/Uba2p heterodimer.  

PubMed Central

SMT3 is an essential Saccharomyces cerevisiae gene encoding a 11.5 kDa protein similar to the mammalian ubiquitin-like protein SUMO-1. We have found that Smt3p, like SUMO-1 and ubiquitin, can be attached to other proteins post-translationally and have characterized the processes leading to the activation of the Smt3p C-terminus for conjugation. First, the SMT3 translation product is cleaved endoproteolytically to expose Gly98, the mature C-terminus. The presence of Gly98 is critical for Smt3p's abilities to be conjugated to protein substrates and to complement the lethality of a smt3Delta strain. Smt3p undergoes ATP-dependent activation by a novel heterodimeric enzyme consisting of Uba2p, a previously identified 71 kDa protein similar to the C-terminus of ubiquitin-activating enzymes (E1s), and Aos1p (activation of Smt3p), a 40 kDa protein similar to the N-terminus of E1s. Experiments with conditional uba2 mutants showed that Uba2p is required for Smt3p conjugation in vivo. Furthermore, UBA2 and AOS1 are both essential genes, providing additional evidence that they act in a distinct pathway whose role in cell viability is to conjugate Smt3p to other proteins.

Johnson, E S; Schwienhorst, I; Dohmen, R J; Blobel, G

1997-01-01

266

Phosphorylation of the Aspergillus oryzae Woronin body protein, AoHex1, by protein kinase C: evidence for its role in the multimerization and proper localization of the Woronin body protein.  

PubMed

Woronin body, a specialized peroxisome, is a unique organelle involved in septal pore sealing and protecting filamentous fungus from excessive cytoplasmic bleeding. We recently characterized the Aohex1 gene encoding the major protein of the Woronin body in the fungus Aspergillus oryzae. Although three-dimensional microscopy revealed plugging of the septal pore by Woronin body, the mechanism of its formation remains unknown. We report here a reduction in the oligomeric forms (dimeric and tetrameric) of AoHex1 upon l-phosphatase treatment, which indicated that AoHex1 phosphorylation in vivo facilitates its oligomerization. Concomitant with the presence of a highly conserved predicted PKC (protein kinase C)-phosphorylatable site (Ser151), the recombinant AoHex1 was phosphorylated by PKC in vitro and the administration of the PKC inhibitors, bisindolylmaleimide I and chelerythrine, resulted in the reduction of the oligomeric forms of AoHex1 in vivo. While spherical dot-like Woronin bodies were visualized by expressing the dsred2-Aohex1 and egfp (enhanced green fluorescent protein)-Aohex1 constructs in A. oryzae, treatment with the PKC inhibitors caused an abnormal localization to ring-like structures. In addition to the reduced phosphorylation of the mutagenized recombinant AoHex1[S151A] (Ser151 to alanine substitution) by PKC in vitro, the overexpression of Aohex1[S151A] as dsred2 fusion against the wild-type background also showed reduction of the oligomeric forms of the endogenous AoHex1 and its perturbed localization to ring-like structures in vivo. In conclusion, the present study implicates the relevance of PKC-dependent phosphorylation of the Woronin body protein, AoHex1, for its multimerization and proper localization. PMID:17441786

Juvvadi, Praveen Rao; Maruyama, Jun-ichi; Kitamoto, Katsuhiko

2007-08-01

267

Multi-watt 589-nm Na D2-line generation via frequency doubling of a Raman fiber amplifier: a source for LGS-assisted AO  

NASA Astrophysics Data System (ADS)

We develop a novel solid state fibre laser system, AFIRE, for the purposes of laser guidestar (LGS) assisted adaptive optics (AO), based on the second harmonic generation (SHG) from a high-power (P1178 ~25W) CW narrowband (?? < 3GHz) Raman fibre amplifier developed by IPF. We present what we believe to be the highest power, narrowband single-pass CW 589nm SHG result reported to date, P589 ~ 4.2W from P1178 ~ 19W (?VIS > 22%). We demonstrate our understanding of the arising absorption-induced thermal effects (namely, dephasing and degradation of the conversion), offer predictions towards higher powers and conversion levels, and show that our current results are essentially pump-power limited. We are confident of the scalability of both the IR and visible parts of our system, to these higher output powers and conversion efficiencies.

Taylor, L.; Feng, Y.; Bonaccini Calia, D.; Hackenberg, W.

2006-07-01

268

Volcanic activity of Io observed in December 2001 with the Keck AO system: 2-5? m sunlit and eclipse observations  

NASA Astrophysics Data System (ADS)

Volcanically active Io remains a mysterious and intriguing moon, despite numerous spacecraft flybys. Groundbased monitoring programs help characterize the time evolution of Io's volcanic activity, such as the frequency, spatial distribution and temperature of hot spots and outbursts. The satellite was observed intensively in December 2001 with the Keck II Adaptive Optics (AO) system and its recently installed near-infrared camera NIRC2. The spatial resolution after applying the MISTRAL myopic deconvolution method (130 km in K band and 200 km in L band) is better than that of the global images from the Galileo/NIMS instrument. A movie produced from 12 pictures taken every 30o in Ionian longitude provides a complete survey of Io's surface during one full rotation. A total of 26 active hot spots were detected in L band (3.8? m), and approximatively three times more in M band (4.7? m). One active hot spot is seen in K band (2.2? m) in the Pele area. While Io is in Jupiter's shadow, it is invisible to the wavefront sensor, but its hot spots are easily visible in the near-infrared. We imaged Io during the 18 Dec. 2001 eclipse using Ganymede (30" from Io, moving relative to Io at 0.5"/min) as a reference source. Although isoplanatic effects limited AO performance, numerous spots are detected at both K' and L'. We will show the results of detailed studies (temperature, emission area, nature) for several of the hot spots. Keck Science team is composed of S. Kwok, P. Amico, R. Campbell, F. Chaffee, A. Conrad, A. Contos, B. Goodrich, G. Hill, D. Sprayberry, P. Stomski, P. Wizinowich (W.M. Keck Observatory). This work has been supported in part by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783.

Marchis, F.; de Pater, I.; Le Mignant, D.; Roe, H.; Fusco, T.; Graham, J. R.; Prange, R.; Macintosh, B.; Keck Science Team

2002-09-01

269

Separation, characterization and dose-effect relationship of the PPARgamma-activating bio-active constituents in the Chinese herb formulation 'San-Ao decoction'.  

PubMed

San-ao decoction (SAD), comprising Herba Ephedrae, Radix et Rhizoma Glycyrrhizae and Seneb Armeniacae Amarum, is one of the most popular traditional Chinese medicine (TCM) formulae for asthma. Peroxisome proliferator-activated receptors (PPARs) areey regulators of lipid and glucose metabolism and have become important therapeutic targets for various deseases, PPARgamma activation might exhibit anti-inflammatory properties in different chronic inflammatory processes. The EtOAc fraction of SAD showed a significant effect on PPARgamma activation. A simple and rapid method has been established for separation and characterization of the main compounds in the PPARgamma-activating fraction of SAD by ultra-fast HPLC coupled with quadropole time-of-flight mass pectrometry (UPLC-Q-TOF/MS). A total of 10 compounds were identified in the activating fraction of SAD, including amygdalin (1), liquiritin (2), 6'-acetyliquiritin (3), liquiritigenin (4), isoliquiritigenin (5), formononetin (6), licoisoflavanone (7), glycycoumarin (8), glycyrol (9) and uercetin (10). The results also characterized formononetin as a predominant component in this fraction. The dose-effect relationship comparison study of formononetin and the EtOAc fraction of SAD by adding formononetin was performed, the results suggested that formononetin was the major component of the EtOAc fraction of SAD responsible for activating PPARgamma, and the method will possibly be applied to study the complex biological active constituents of other TCMs. PMID:19924040

Zhou, Ling; Tang, Yu-Ping; Gao, Lu; Fan, Xin-Sheng; Liu, Chun-Mei; Wu, De-Kang

2009-01-01

270

Influence of spinel substrate and over-layer for enhanced SAW and AO properties with KNbO3 thin film.  

PubMed

Surface acoustic wave (SAW) propagation characteristics have been studied using modeling calculations for a potassium niobate (KNbO3) thin film-layered structure with (001) and (110) orientation on a single crystal spinel (MgAl2O4) substrate, and a spinel buffer layer on silicon. Variation in the electromechanical coupling and acoustic attenuation has been compared. A significantly high value of coupling factor (k2max = 23%) is obtained for the (001)KNbO3/spinel structure by introducing an optimum thickness of spinel over-layer for potential wide bandwidth SAW device applications. The dispersion characteristics with the (110) KNbO3 orientation indicate an initial peak in the coupling coefficient value (k2max = 8.8%) at a relatively low KNbO3 film thickness that appears attractive for fabricating devices with thinner films. The KNbO3 film with (001) orientation is found attractive for efficient acousto-optic (AO) device application with the formation of a symmetric waveguide structure (spinel(0.5 microm)/KNbO3(1.0 microm)/spinel). A high value of k2 = 23.5% with 50% diffraction efficiency has been obtained for the spinel(0.5 microm)/KNbO3(1.0 microm)/spinel structure at 1 GHz SAW frequency and 633 nm optical wavelength at a very low input drive power of 15.4 mW. PMID:12839169

Nayak, Ranu; Gupta, Vinay; Sreenivas, Kondepudy

2003-06-01

271

Summary Report of the First International Symposium on Strain Gauge Balances and Workshop on AoA/Model Deformation Measurement Techniques  

NASA Technical Reports Server (NTRS)

The first International Symposium on Strain Gauge Balances was sponsored under the auspices of the NASA Langley Research Center (LaRC), Hampton, Virginia during October 22-25, 1996. Held at the LaRC Reid Conference Center, the Symposium provided an open international forum for presentation, discussion, and exchange of technical information among wind tunnel test technique specialists and strain gauge balance designers. The Symposium also served to initiate organized professional activities among the participating and relevant international technical communities. The program included a panel discussion, technical paper sessions, tours of local facilities, and vendor exhibits. Over 130 delegates were in attendance from 15 countries. A steering committee was formed to plan a second international balance symposium tentatively scheduled to be hosted in the United Kingdom in 1998 or 1999. The Balance Symposium was followed by the half-day Workshop on Angle of Attack and Model Deformation on the afternoon of October 25. The thrust of the Workshop was to assess the state of the art in angle of attack (AoA) and model deformation measurement techniques and to discuss future developments.

Tripp, John S.; Tcheng, Ping; Burner, Alpheus W.; Finley, Tom D.

1999-01-01

272

Summary Report of the First International Symposium on Strain Gauge Balances and Workshop on AoA/Model Deformation Measurement Techniques  

NASA Technical Reports Server (NTRS)

The first International Symposium on Strain Gauge Balances was sponsored under the auspices of the NASA Langley Research Center (LaRC), Hampton, Virginia. Held at the LaRC Reid Conference Center, the Symposium provided an open international forum for presentation, discussion, and exchange of technical information among wind tunnel test technique specialists and strain gauge balance designers. The Symposium also served to initiate organized professional activities among the participating and relevant international technical communities. The program included a panel discussion, technical paper sessions, tours of local facilities, and vendor exhibits. Over 130 delegates were in attendance from 15 countries. A steering committee was formed to plan a second international balance symposium tentatively scheduled to be hosted in the United Kingdom in 1998 or 1999. The Balance Symposium was followed bv the half-day, Workshop on Angle of Attack and Model Deformation on the afternoon of October 25. The thrust of the Workshop was to assess the state of the art in angle of attack (AoA) and model deformation measurement techniques and to discuss future developments.

Tripp, John S.; Tcheng, Ping; Burner, Alpheus W.; Finley, Tom D.

1998-01-01

273

Resonance tube hazards in oxygen systems. Ph.D. Thesis - Toledo Univ., 1975  

NASA Technical Reports Server (NTRS)

An experimental and analytical program was carried out to determine whether fluid dynamic oscillations could create a hazard in gaseous oxygen flow systems. The particular fluid dynamic oscillation studied was the resonance tube phenomena as it was excited in a tee-shaped configuration characteristic of configurations found in many industrial high pressure gas flow systems. The types of hazards that could be caused by the oscillations were direct heating and ignition of the piping system by the gas, the greatly augmented heating that could occur if inert contaminants were present, and the ignition of metallic contaminants. Asbestos was used as the inert contaminant; titanium, aluminum, magnesium and steel were chosen as ignitable metallic contaminants. The oscillations in the tee-shaped configuration were compared to oscillations driven by choked convergent nozzles and were found to differ markedly. Temperature generated at the end or base of the resonance tube exceeded 1089 K for both gaseous oxygen and nitrogen and reached 1645 K when asbestos was added. Aluminum in both powder and fiber form was readily ignited within the resonance tube when the supply pressures were less than 8270 kPa whereas at higher supply pressures the mixture exploded with enough violence to destory the apparatus in less than 10 sec. In addition to aluminum, magnesium, and titanium, samples of 400 series stainless steels were also ignited within the resonance tube. The ignition occurred within a few seconds after the oxygen flow began.

Phillips, B. R.

1982-01-01

274

Active feed array compensation for reflector antenna surface distortions. Ph.D. Thesis - Akron Univ., Ohio  

NASA Technical Reports Server (NTRS)

The feasibility of electromagnetic compensation for reflector antenna surface distortions is investigated. The performance characteristics of large satellite communication reflector antenna systems degrade as the reflector surface distorts, mainly due to thermal effects from solar radiation. The technique developed can be used to maintain the antenna boresight directivity and sidelobe level independent of thermal effects on the reflector surface. With the advent of monolithic microwave integrated circuits (MMIC), a greater flexibility in array fed reflector antenna systems can be achieved. MMIC arrays provide independent control of amplitude and phase for each of the many radiating elements in the feed array. By assuming a known surface distortion profile, a simulation study is carried out to examine the antenna performance as a function of feed array size and number of elements. Results indicate that the compensation technique can effectively control boresight directivity and sidelobe level under peak surface distortion in the order of tenth of a wavelength.

Acosta, Roberto J.

1988-01-01

275

Contribution to the study of composite materials and their damage. Thesis - Paris VI Univ. - 1984  

NASA Technical Reports Server (NTRS)

Chapter 1 describes the homogenization techniques used for defining the overall behavior of composite materials for conventional cases of linear and perfectly glued elastic constituents. Chapters 2 and 3 focus on solving the problems inherent in two types of degenerated situations: elastic media with microcavities, and elastic media containing rigid inclusions. Through suitable definitions of deformation concepts and macroscopic stresses it is shown that conventional theory results apply naturally to these limits.

Lene, F.

1987-01-01

276

Elementary particle interactions. [Dept. of Physics and Astronomy, Univ. of Tennessee, Knoxville, Tennessee  

SciTech Connect

Work continues on strange particle production in weak interactions using data from a high-energy neutrino exposure in a freon bubble chamber. Meson photoproduction has also consumed considerable effort. Detector research and development activities have been carried out.

Bugg, W.M.; Condo, G.T.; Handler, T.; Hart, E.L.; Read, K.; Ward, B.F.L.

1992-10-01

277

Theory of elementary particles and accelerator theory: Task C: Experimental high energy physics. [Univ. of Oregon  

SciTech Connect

The experimental high energy physics group at the University of Oregon broadened its effort during the past year. The SLD effort extends from maintaining and operating the SLD luminosity monitor which was built at Oregon, to significant responsibility in physics analysis, such as event selection and background analysis for the left-right asymmetry measurement. The OPAL work focussed on the luminosity monitor upgrade to a silicon-tungsten calorimeter. Building on the work done at Oregon for SLD, the tungsten for this upgrade was machined by the Oregon shops and shipped to CERN for assembly. The Oregon GEM effort now concentrates on tracking, specifically silicon tracking. Oregon also has developed a silicon strip preradiator prototype, and tested it in a Brookhaven beam.

Brau, J.E.

1992-01-01

278

Liquid jet impingement normal to a disk in zero gravity. Ph.D. Thesis Toledo Univ.  

NASA Technical Reports Server (NTRS)

The free surface shapes of circular liquid jets impinging normal to sharp-edged disks in zero gravity are determined. Zero gravity drop tower experiments yielded three distinct flow patterns that were classified in terms of the relative effects of surface tension and inertial forces. An order of magnitude analysis was conducted that indicated regions where viscous forces were not significant in the computation of free surface shapes. The free surface analysis was simplified by transforming the governing potential flow equations and boundary conditions into the inverse plane, where the stream function and velocity potential became the coordinates. The resulting nonlinear equations were solved by standard finite difference methods, and comparisons were made with the experimental data for the inertia dominated regime.

Labus, T. L.

1977-01-01

279

Nuclear structure theory. Annual technical progress report, October 1, 1979-August 31, 1980. [Univ. of Rochester  

SciTech Connect

This report summarizes progress during the past year in the following areas of nuclear structure and reaction theory: statistical spectroscopy (including random matrix methods, with applications to fluctuations in spectra and in strength distributions, and to problems of ergodicity; group symmetries in spectral-distribution theory; electromagnetic and ..beta.. transitions); meson scattering and absorption by nuclei (including general scattering theory with absorption, multiple scattering theory and its reactive content, statistical theory of absorption); and meson currents in electromagnetic transitions.

French, J.B.; Koltun, D.S.

1980-01-01

280

Chaotic dynamics in accelerator physics. [Dept. of Astrophysical, Planetary, and Atmospheric Sciences, Univ. of Colorado, Boulder  

SciTech Connect

Substantial progress was in several areas of accelerator dynamics. For developing understanding of longitudinal adiabatic dynamics, and for creating efficiency enhancements of recirculating free-electron lasers, was substantially completed. A computer code for analyzing the critical KAM tori that bound the dynamic aperture in circular machines was developed. Studies of modes that arise due to the interaction of coating beams with a narrow-spectrum impedance have begun. During this research educational and research ties with the accelerator community at large have been strengthened.

Cary, J.R.

1992-11-30

281

Studies in theoretical high energy particle physics. [Dept. of Physics, Univ. of Illinois at Chicago  

SciTech Connect

Theoretical work on the following topics is briefly summarized: symmetry structure of conformal affine Toda model and KP hierarchy; solitons in the affine Toda and conformal affine Toda models; classical r-matrices and Poisson bracket structures on infinite-dimensional groups; R-matrix formulation of KP hierarchies and their gauge equivalence; statistics of particles and solitons; charge quantization in the presence of an Alice string; knotting and linking of nonabelian flux; electric dipole moments; neutrino physics in gauge theories; CP violation in the high energy colliders; supersymmetric quantum mechanics; parton structure functions in nuclei; dual parton model. 38 refs.

Aratyn, H.; Brekke, L.; Keung, Wai-Yee; Sukhatme, U.

1993-01-01

282

Physics of Nonmagnetic Relativistic Thermal Plasmas. Ph.D. Thesis - Calif. Univ., San Diego  

NASA Technical Reports Server (NTRS)

A detailed treatment of the kinematics of relativistic systems of particles and photons is presented. In the case of a relativistic Maxwell-Boltzmann distribution of particles, the reaction rate and luminosity are written as single integrals over the invariant cross section, and the production spectrum is written as a double integral over the cross section differential in the energy of the produced particles (or photons) in the center-of-momentum system of two colliding particles. The results are applied to the calculation of the annihilation spectrum of a thermal electron-positron plasma, confirming previous numerical and analytic results. Relativistic thermal electron-ion and electron-electron bremsstrahlung are calculated exactly to lowest order, and relativistic thermal electron-positron bremsstrahlung is calculated in an approximate fashion. An approximate treatment of relativistic Comptonization is developed. The question of thermalization of a relativistic plasma is considered. A formula for the energy loss or exchange rate from the interaction of two relativistic Maxwell-Boltzmann plasmas at different temperatures is derived. Application to a stable, uniform, nonmagnetic relativistic thermal plasma is made. Comparison is made with other studies.

Dermer, C. D.

1984-01-01

283

Condensed matter research using the UCSB FEL. [Univ. of California, Santa Barbara Free Electron Laser project  

SciTech Connect

The University of California, Santa Barbara (UCSB) Free Electron Laser (FEL) project was initiated in 1981 to test the idea of using an electrostatic accelerator in a recirculating beam mode to produce high-power, continuously tunable, coherent far infrared radiation. The development and application of this device to condensed matter research are briefly recounted. Emphasis was on semiconductor research and two-photon experiments. (RWR)

Not Available

1992-01-01

284

[Spin dependent phenomena in medium energy physics]. [Syracuse Univ. , Syracuse, New York  

SciTech Connect

The Syracuse University Medium Energy Physics Group was actively engaged in several research projects. A laser was used to polarize muonic atoms with the goal of measuring fundamental spin-dependent parameters in the reaction [mu][sup [minus

Souder, P.A.

1992-11-01

285

Hydrodynamic models of a cepheid atmosphere. Ph.D. Thesis - Maryland Univ., College Park  

NASA Technical Reports Server (NTRS)

A method for including the solution of the transfer equation in a standard Henyey type hydrodynamic code was developed. This modified Henyey method was used in an implicit hydrodynamic code to compute deep envelope models of a classical Cepheid with a period of 12(d) including radiative transfer effects in the optically thin zones. It was found that the velocity gradients in the atmosphere are not responsible for the large microturbulent velocities observed in Cepheids but may be responsible for the occurrence of supersonic microturbulence. It was found that the splitting of the cores of the strong lines is due to shock induced temperature inversions in the line forming region. The adopted light, color, and velocity curves were used to study three methods frequently used to determine the mean radii of Cepheids. It is concluded that an accuracy of 10% is possible only if high quality observations are used.

Karp, A. H.

1974-01-01

286

Experimental investigations in particle physics at intermediate energies. [Physics Dept. , Temple Univ  

SciTech Connect

The major emphasis of this project continues to be on fundamental symmetries and parameters of the Standard Model. A test of a quark model prediction was also done. The projects in the current period have been the following: LSND, a neutrino oscillation experiment at LAMPF; E791, a search for the decays K{sub L}{sup 0} {yields} {mu}e and K{sub L}{sup 0} {yields} ee; E871, tests and preparations for an upgrade proposal; and E888, a search for the H dibaryon. The LSND (Large Scintillator Neutrino Detector) is under construction at this time. Progress in the construction schedule has been accelerated with the expectation of being ready to accept beam in March 1993. The automated system for testing photomultiplier tubes is in full production, and should be able to certify a fun complement of tubes for installation by October 1992. Results of an earlier LAMPF experiment, E764, on the interaction of muon neutrinos with carbon nuclei have been submitted for publication. A thorough 'blind' analysis of the E791 data set has just been brought to completion. Final results for the upper limits (90% C.L.) on the branching ratios for the decays K{sub L}{sup 0} {yields} {mu}e and K{sub L}{sup 0} {yields} ee are 3.3 {times} 10{sup {minus}11} and 4.1 {times} 10{sup {minus}11}, respectively. The final result for the branching ratio for K{sub L}{sup 0} {yields} {mu}{mu} from all the data (720 events) is (7.0 {plus minus} 0.4 {plus minus} 0.2) {times} 10{sup {minus}9}. The potential of the E791 detector for rare K decays has reached its limit. Before disassembly it was used to mount a search (E888) for a possible long-lived six-quark state, the H. At the same time studies have been made of an upgraded version of the experiment (E871) that will make use of a portion of the existing apparatus.

Auerbach, L.B.; Highland, V.L.; McFarlane, K.W.; Kettell, S.H.

1992-07-12

287

Noise transmission through plates into an enclosure. M.S. Thesis - George Washington Univ.  

NASA Technical Reports Server (NTRS)

An analytical model is presented to predict noise transmission through elastic plates into a hard-walled rectangular cavity at low frequencies, that is, frequencies up through the first few plate and cavity natural frequencies. One or several nonoverlapping and independently vibrating panels are considered. The effects on noise transmission of different external-pressure excitations, plate boundary conditions, fluid parameters, structural parameters, and geometrical parameters were investigated.

Mcdonald, W. B.; Vaicaitis, R.; Myers, M. K.

1978-01-01

288

High energy hadron-hadron collisions. [Dept. of Physics and Astronomy, Univ. of Georgia, Athens, Georgia  

SciTech Connect

Results of a study on high energy collisions with the geometrical model are summarized in three parts: (1) the elastic hadron-hadron collision, (2) the inelastic hadron-hadron collision, and (3) e[sup +]e[sup [minus

Chou, T.T.

1992-01-01

289

Research in elementary particle physics. [Dept. of Physics and Astronomy, Louisiana State Univ,. Baton Rouge, Louisiana  

SciTech Connect

Theoretical work on effective action expansion on an effective low; energy theory of hadron, dynamical symmetry breaking, and lattice gauge theories is described. The high-energy experimental group at Louisiana State University has analyzed data on a neutrino oscillation experiment at LAMPF. Preparations for the LSND neutrino experiment have stated. IMB data have also been analyzed. On the ZEUS electron n-proton colliding bean experiment, the production of the barrel calorimeter has been completed. Several modules of the calorimeter have been tested at Fermilab, and preparations for data taking are underway.

Chan, L.H; Haymaker, R.; Imlay, R.; McNeil, R.; Metcalf, W.; Svoboda, R.

1992-01-01

290

An Empirical Method for Determining the Lunar Gravity Field. Ph.D. Thesis - George Washington Univ.  

NASA Technical Reports Server (NTRS)

A method has been devised to determine the spherical harmonic coefficients of the lunar gravity field. This method consists of a two-step data reduction and estimation process. In the first step, a weighted least-squares empirical orbit determination scheme is applied to Doppler tracking data from lunar orbits to estimate long-period Kepler elements and rates. Each of the Kepler elements is represented by an independent function of time. The long-period perturbing effects of the earth, sun, and solar radiation are explicitly modeled in this scheme. Kepler element variations estimated by this empirical processor are ascribed to the non-central lunar gravitation features. Doppler data are reduced in this manner for as many orbits as are available. In the second step, the Kepler element rates are used as input to a second least-squares processor that estimates lunar gravity coefficients using the long-period Lagrange perturbation equations.

Ferrari, A. J.

1971-01-01

291

Liquid crystal point diffraction interferometer. Ph.D. Thesis - Arizona Univ., 1995  

NASA Technical Reports Server (NTRS)

A new instrument, the liquid crystal point diffraction-interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction. This dissertation describes the theory of both the PDI and liquid crystal phase control. The design considerations for the LCPDI are presented, including manufacturing considerations. The operation and performance of the LCPDI are discussed, including sections regarding alignment, calibration, and amplitude modulation effects. The LCPDI is then demonstrated using two phase objects: defocus difference wavefront, and a temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to theoretical or independently measured results and show excellent agreement. A computer simulation of the LCPDI was performed to verify the source of observed periodic phase measurement error. The error stems from intensity variations caused by dye molecules rotating within the liquid crystal layer. Methods are discussed for reducing this error. Algorithms are presented which reduce this error; they are also useful for any phase-stepping interferometer that has unwanted intensity fluctuations, such as those caused by unregulated lasers.

Mercer, Carolyn R.

1995-01-01

292

Solid state polymerization and crystallography of polyimide precursors. Ph.D. Thesis - Va. Univ.  

NASA Technical Reports Server (NTRS)

Although the production of crystallinity in a polymeric system has historically led to commerically useful properties, the polyimides, prized for their high temperature characteristics, as customarily synthesized by melt or solution casting, are amorphous. It is shown that polymide containing residual crystallinity can be synthesized by isothermal annealing of crystals of the salt of the diisopropyl ester of pyromellitic acid and phenylene diamine. The reaction is topochemical in that the geometry of the polymer product is dependent upon that of the crystalline precursor. Infrared spectroscopy reveals the presence of imide absorption in the polymer, while powder diffractometry suggests residual crystallinity. Single crystal X-ray analysis of the monomer yields a structure of chains of alternating acid and base suggesting that the monomer is amenable to polymerization with a minimum of geometrical disruption.

Wakelyn, N. T.

1974-01-01

293

Task A: Theory of elementary particles. [Inst. of Theoretical Science, Univ. of Oregon, Eugene, Oregon  

SciTech Connect

Brief summaries of work are given in the following areas: grandunification, properties of neutrinos, rare decays of heavy quarks, jet production in hadron collisions (theory, structure, two-jet cross section, null-plane field theory), neutrino physics, and QCD calculations of annihilation of e[sup +]e[sup [minus

Deshpande, N.G.; Soper, D.E.

1992-10-16

294

Random Process Simulation for stochastic fatigue analysis. Ph.D. Thesis - Rice Univ., Houston, Tex.  

NASA Technical Reports Server (NTRS)

A simulation technique is described which directly synthesizes the extrema of a random process and is more efficient than the Gaussian simulation method. Such a technique is particularly useful in stochastic fatigue analysis because the required stress range moment E(R sup m), is a function only of the extrema of the random stress process. The family of autoregressive moving average (ARMA) models is reviewed and an autoregressive model is presented for modeling the extrema of any random process which has a unimodal power spectral density (psd). The proposed autoregressive technique is found to produce rainflow stress range moments which compare favorably with those computed by the Gaussian technique and to average 11.7 times faster than the Gaussian technique. The autoregressive technique is also adapted for processes having bimodal psd's. The adaptation involves using two autoregressive processes to simulate the extrema due to each mode and the superposition of these two extrema sequences. The proposed autoregressive superposition technique is 9 to 13 times faster than the Gaussian technique and produces comparable values for E(R sup m) for bimodal psd's having the frequency of one mode at least 2.5 times that of the other mode.

Larsen, Curtis E.

1988-01-01

295

CRCHD - CRCHD Research - Univ. of Guam/Cancer Res. Center of Hawaii Partnership  

Cancer.gov

The University of Guam (UOG) is the only four-year institution of higher learning in the Western Pacific serving the U.S. territories of Guam and the Commonwealth of the Northern Mariana Islands, as well as all of Micronesia. The student population consists of approximately 50% Pacific Islanders, 32% Filipino, 9% Caucasians, 8% Asians, and 1% other minorities. The University operates interdisciplinary research programs including marine biology, water and environmental research, Micronesian language and area studies, and Micronesian health and aging studies.

296

Evolution of domain walls in the early universe. Ph.D. Thesis - Chicago Univ.  

NASA Technical Reports Server (NTRS)

The evolution of domain walls in the early universe is studied via 2-D computer simulation. The walls are initially configured on a triangular lattice and then released from the lattice, their evolution driven by wall curvature and by the universal expansion. The walls attain an average velocity of about 0.3c and their surface area per volume (as measured in comoving coordinates) goes down with a slope of -1 with respect to conformal time, regardless of whether the universe is matter or radiation dominated. The additional influence of vacuum pressure causes the energy density to fall away from this slope and steepen, thus allowing a situation in which domain walls can constitute a significant portion of the energy density of the universe without provoking an unacceptably large perturbation upon the microwave background.

Kawano, Lawrence

1989-01-01

297

Liquid jet impingement normal to a disk in zero gravity. Ph.D. Thesis - Toledo Univ.  

NASA Technical Reports Server (NTRS)

An experimental and analytical investigation was conducted to determine the free surface shapes of circular liquid jets impinging normal to sharp-edged disks under both normal and zero gravity conditions. An order of magnitude analysis was conducted indicating regions where viscous forces were not significant when computing free surface shapes. The demarcation between the viscous and inviscid region was found to depend upon the flow Reynolds number and the ratio between the jet and disk radius.

Labus, T. L.

1976-01-01

298

D'un univers culturel a l'autre (From One Cultural Universe to Another).  

ERIC Educational Resources Information Center

It is possible to develop an intermediate cultural system much like the interlanguage developed at the intermediate stage by a language learner. Techniques used by one teacher of French are described and discussed. (MSE)

Molinie, Muriel

1988-01-01

299

Pulsed multiwavelength laser ranging system. Ph.D. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

A pulsed multiwavelength laser ranging system for measuring atmospheric delay was built and tested, and its theoretical performance limits were calculated. The system uses a dye modelocked ND:YAG laser, which transmits 70 psec wide pulses simultaneously at 1064, 532, and 355 nm. The differential delay of the 1064 and 355 nm pulses is measured by a specially calibrated waveform digitizer to estimate the dry atmospheric delay. The delay time of the 532 nm pulse is used to measure the target distance. Static crossed field photomultipliers are used as detectors for all wavelengths. Theoretical analysis shows that path curvature and atmospheric turbulence are fundamental limits to the ranging accuracy of both single and multicolor systems operating over horizontal paths. For two color systems, an additional error is caused by the uncertainty in the path averaged water vapor. The standard deviation of the multicolor instrument's timing measurements is directly proportional to the laser pulse width plus photomultiplier jitter divided by the square root of the received photoelectron number. The prototype system's maximum range is km, which is limited by atmospheric and system transmission losses at 355 nm. System signal detection and false alarm calculations are also presented.

Abshire, J. B.

1982-01-01

300

[Investigations in dynamics of gauge theories in theoretical particle physics]. [Virginia Polytechnic Institute State Univ. , Blacksburg  

SciTech Connect

The major theme of the theoretical physics research conducted under DOE support over the past several years has been within the rubric of the standard model, and concerned the interplay between symmetries and dynamics. The research was thus carried out mostly in the context of gauge field theories, and usually in the presence of chiral fermions. Dynamical symmetry breaking was examined both from the point of view of perturbation theory, as well as from non-perturbative techniques associated with certain characteristic features of specific theories. Among the topics of research were: the implications of abelian and non-abelian anomalies on the spectrum and possible dynamical symmetry breaking in any theory, topological and conformal properties of quantum fields in two and higher dimensions, the breaking of global chiral symmetries by vector-like gauge theories such as QCD, the phenomenological implications of a strongly interacting Higgs sector in the standard model, and the application of soliton ideas to the physics to be explored at the SSC.

Not Available

1993-01-01

301

A prediction model for lift-fan simulator performance. M.S. Thesis - Cleveland State Univ.  

NASA Technical Reports Server (NTRS)

The performance characteristics of a model VTOL lift-fan simulator installed in a two-dimensional wing are presented. The lift-fan simulator consisted of a 15-inch diameter fan driven by a turbine contained in the fan hub. The performance of the lift-fan simulator was measured in two ways: (1) the calculated momentum thrust of the fan and turbine (total thrust loading), and (2) the axial-force measured on a load cell force balance (axial-force loading). Tests were conducted over a wide range of crossflow velocities, corrected tip speeds, and wing angle of attack. A prediction modeling technique was developed to help in analyzing the performance characteristics of lift-fan simulators. A multiple linear regression analysis technique is presented which calculates prediction model equations for the dependent variables.

Yuska, J. A.

1972-01-01

302

Annual Conference in Rhetorical Criticism: Commended Papers (6th, California State Univ., Hayward, May, 1972).  

ERIC Educational Resources Information Center

At this 1972 conference, upper division and graduate students from nine western colleges submitted papers on the theory, history, and criticism of rhetoric. Three of them are published in this conference report, along with the principal address. In "Rhetorical Criticism as Argument," the principal address, Wayne Brockriede suggests that useful…

Chalip, Alice Grace, Ed.

303

Compressible flows with periodic vortical disturbances around lifting airfoils. Ph.D. Thesis - Notre Dame Univ.  

NASA Technical Reports Server (NTRS)

A numerical method is developed for solving periodic, three-dimensional, vortical flows around lifting airfoils in subsonic flow. The first-order method that is presented fully accounts for the distortion effects of the nonuniform mean flow on the convected upstream vortical disturbances. The unsteady velocity is split into a vortical component which is a known function of the upstream flow conditions and the Lagrangian coordinates of the mean flow, and an irrotational field whose potential satisfies a nonconstant-coefficient, inhomogeneous, convective wave equation. Using an elliptic coordinate transformation, the unsteady boundary value problem is solved in the frequency domain on grids which are determined as a function of the Mach number and reduced frequency. The numerical scheme is validated through extensive comparisons with known solutions to unsteady vortical flow problems. In general, it is seen that the agreement between the numerical and analytical results is very good for reduced frequencies ranging from 0 to 4, and for Mach numbers ranging from .1 to .8. Numerical results are also presented for a wide variety of flow configurations for the purpose of determining the effects of airfoil thickness, angle of attack, camber, and Mach number on the unsteady lift and moment of airfoils subjected to periodic vortical gusts. It is seen that each of these parameters can have a significant effect on the unsteady airfoil response to the incident disturbances, and that the effect depends strongly upon the reduced frequency and the dimensionality of the gust. For a one-dimensional (transverse) or two-dimensional (transverse and longitudinal) gust, the results indicate that airfoil thickness increases the unsteady lift and moment at the low reduced frequencies but decreases it at the high reduced frequencies. The results show that an increase in airfoil Mach number leads to a significant increase in the unsteady lift and moment for the low reduced frequencies, but a significant decrease for the high reduced frequencies.

Scott, James R.

1991-01-01

304

Contribution to the Performance Determination of Microjets. Ph.D. Thesis - Technical Univ., Feb. 1983  

NASA Technical Reports Server (NTRS)

Theoretical investigations are made on the performance of microjets. A description is given of experiments with micropropulsion units to correlate the results obtained in the first part of the report. Execution of performance measurements is discussed, and error calculations are presented.

Hayn, D.

1984-01-01

305

Semiempirical studies of atomic structure. [Dept. of Physics and Astronomy, Univ. of Toledo  

SciTech Connect

The energy level structure, transition probabilities, and general spectroscopic properties of highly ionized many-electron systems are studied through the combined use of sensitive semiempirical data systematizations, selected precision experimental measurements, and specialized theoretical computations. Measurements are made primarily through the use of fast ion beam excitation methods, which are combined with available data from laser-and tokamak-produced plasmas, astrophysical sources, and conventional light sources. The experimental studies are strengthened through large-scale ab initio calculations. Typical examples are the following: lifetime measurements in the neon isoelectronic sequence; multiplexed decay curve measurements of Li-like Si XII; and isoelectronic specification of intershell resonance and intercombination decay rates using measured transition probabilities and spectroscopically determined singlet-mixing amplitudes.

Curtis, L.J.

1992-01-01

306

A contracting-interval program for the Danilewski method. Ph.D. Thesis - Va. Univ.  

NASA Technical Reports Server (NTRS)

The concept of contracting-interval programs is applied to finding the eigenvalues of a matrix. The development is a three-step process in which (1) a program is developed for the reduction of a matrix to Hessenberg form, (2) a program is developed for the reduction of a Hessenberg matrix to colleague form, and (3) the characteristic polynomial with interval coefficients is readily obtained from the interval of colleague matrices. This interval polynomial is then factored into quadratic factors so that the eigenvalues may be obtained. To develop a contracting-interval program for factoring this polynomial with interval coefficients it is necessary to have an iteration method which converges even in the presence of controlled rounding errors. A theorem is stated giving sufficient conditions for the convergence of Newton's method when both the function and its Jacobian cannot be evaluated exactly but errors can be made proportional to the square of the norm of the difference between the previous two iterates. This theorem is applied to prove the convergence of the generalization of the Newton-Bairstow method that is used to obtain quadratic factors of the characteristic polynomial.

Harris, J. D.

1971-01-01

307

Boundary-layer separation on isolated boattail nozzles. M.S. Thesis - George Washington Univ.  

NASA Technical Reports Server (NTRS)

An angle of attack of 0 deg was investigated in the Langley 16 foot transonic tunnel at free-stream Mach numbers from 0.40 to 0.95 to study the phenomenon of separated flow on a series of circular-arc afterbodies. Both high-pressure air and solid circular cylinders with the cylinder diameter equal to the nozzle-exit diameter were used to simulate jet exhausts. The results indicate that boundary-layer separation is most extensive on steep boattails at high Mach numbers. The jet total-pressure ratio changes (jet total pressure to free-stream static pressure) affected the extent of separation very little; however, comparison of the separation data obtained by using the two jet-simulation techniques indicate that entrainment associated with the presence of a jet had a significant effect on the extent of separation. The solid-simulator separation data were also used to evaluate the predictions of eight separation criteria.

Abeyounis, W. K.

1978-01-01

308

The sound of moving bodies. Ph.D. Thesis - Cambridge Univ.  

NASA Technical Reports Server (NTRS)

The importance of the quadrupole source term in the Ffowcs, Williams, and Hawkings (FWH) equation was addressed. The quadrupole source contains fundamental components of the complete fluid mechanics problem, which are ignored only at the risk of error. The results made it clear that any application of the acoustic analogy should begin with all of the source terms in the FWH theory. The direct calculation of the acoustic field as part of the complete unsteady fluid mechanics problem using CFD is considered. It was shown that aeroelastic calculation can indeed be made with CFD codes. The results indicate that the acoustic field is the most susceptible component of the computation to numerical error. Therefore, the ability to measure the damping of acoustic waves is absolutely essential both to develop acoustic computations. Essential groundwork for a new approach to the problem of sound generation by moving bodies is presented. This new computational acoustic approach holds the promise of solving many problems hitherto pushed aside.

Brentner, Kenneth Steven

1990-01-01

309

A new approach to telemetry data processing. Ph.D. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

An approach for a preprocessing system for telemetry data processing was developed. The philosophy of the approach is the development of a preprocessing system to interface with the main processor and relieve it of the burden of stripping information from a telemetry data stream. To accomplish this task, a telemetry preprocessing language was developed. Also, a hardware device for implementing the operation of this language was designed using a cellular logic module concept. In the development of the hardware device and the cellular logic module, a distributed form of control was implemented. This is accomplished by a technique of one-to-one intermodule communications and a set of privileged communication operations. By transferring this control state from module to module, the control function is dispersed through the system. A compiler for translating the preprocessing language statements into an operations table for the hardware device was also developed. Finally, to complete the system design and verify it, a simulator for the collular logic module was written using the APL/360 system.

Broglio, C. J.

1973-01-01

310

Contribution to the Performance of Microjets. Ph.D. Thesis - Technical Univ., Feb. 1983  

NASA Technical Reports Server (NTRS)

Theoretical investigations are made on the performance of microjets. A description is given of experiments with micropropulsion units to correlate the results obtained in the first part of the report. Execution of performance measurements is discussed, and error calculations are presented.

Hayn, D.

1984-01-01

311

Thermal behavior spiral bevel gears. Ph.D. Thesis - Case Western Univ., Aug. 1993  

NASA Technical Reports Server (NTRS)

An experimental and analytical study of the thermal behavior of spiral bevel gears is presented. Experimental data were taken using thermocoupled test hardware and an infrared microscope. Many operational parameters were varied to investigate their effects on the thermal behavior. The data taken were also used to validate the boundary conditions applied to the analytical model. A finite element-based solution sequence was developed. The three-dimensional model was developed based on the manufacturing process for these gears. Contact between the meshing gears was found using tooth contact analysis to describe the location, curvatures, orientations, and surface velocities. This information was then used in a three-dimensional Hertzian contact analysis to predict contact ellipse size and maximum pressure. From these results, an estimate of the heat flux magnitude and the location on the finite element model was made. The finite element model used time-averaged boundary conditions to permit the solution to attain steady state in a computationally efficient manner.Then time- and position-varying boundary conditions were applied to the model to analyze the cyclic heating and cooling due to the gears meshing and transferring heat to the surroundings, respectively. The model was run in this mode until the temperature behavior stabilized. The transient flash temperature on the surface was therefore described. The analysis can be used to predict the overall expected thermal behavior of spiral bevel gears. The experimental and analytical results were compared for this study and also with a limited number of other studies. The experimental and analytical results attained in the current study were basically within 10% of each other for the cases compared. The experimental comparison was for bulk thermocouple locations and data taken with an infrared microscope. The results of a limited number of other studies were compared with those obtained herein and predicted the same basic behavior.

Handschuh, Robert F.

1995-01-01

312

Theoretical investigation of electron-positive ion/atom interactions. [Clark Atlanta Univ. , Atlanta, Georgia  

SciTech Connect

Very brief summaries are given on three research topics. Electron impact elastic, excitation, and total cross sections for K were investigated by using elaborate Cl target wave functions in the close-coupling approximation. Photoionization cross sections from ground-state Na were calculated near the 2s[sup 2]2p[sup 5]3s and 2s2p[sup 6]3s inner-shell thresholds; also, the photoionization cross sections of excited 3p [sup 2]P[sup o] and 3d [sup 2]D states were calculated with the R-matrix methodology near the 2s2p[sup 6]3s thresholds. A numerical approach was developed to calculate the charge transfer matrix elements for ion-atom(ion) collisions; this was used for the proton-hydrogen collision problem as an illustration.

Msezane, A.Z.

1992-01-01

313

An indirect optimization method with improved convergence characteristics. Ph.D. Thesis - Houston Univ.  

NASA Technical Reports Server (NTRS)

A method is presented for obtaining numerical solutions to a certain class of two-point boundary value problems which arise in optimal control theory. The problems are characterized by systems of nonlinear ordinary differential equations with nonlinear boundary conditions.

Doiron, H. H.

1972-01-01

314

[Experimental and theoretical high energy physics program]. [Purdue Univ. , West Lafayette, Indiana  

SciTech Connect

Experimental and theoretical high-energy physics research at Purdue is summarized in a number of reports. Subjects treated include the following: the CLEO experiment for the study of heavy flavor physics; gas microstrip detectors; particle astrophysics; affine Kac[endash]Moody algebra; nonperturbative mass bounds on scalar and fermion systems due to triviality and vacuum stability constraints; resonance neutrino oscillations; e[sup +]e[sup [minus

Finley, J.; Gaidos, J.A.; Loeffler, F.J.; McIlwain, R.L.; Miller, D.H.; Palfrey, T.R.; Shibata, E.I.; Shipsey, I.P.

1993-04-01

315

An investigation of gear mesh failure prediction techniques. M.S. Thesis - Cleveland State Univ.  

NASA Technical Reports Server (NTRS)

A study was performed in which several gear failure prediction methods were investigated and applied to experimental data from a gear fatigue test apparatus. The primary objective was to provide a baseline understanding of the prediction methods and to evaluate their diagnostic capabilities. The methods investigated use the signal average in both the time and frequency domain to detect gear failure. Data from eleven gear fatigue tests were recorded at periodic time intervals as the gears were run from initiation to failure. Four major failure modes, consisting of heavy wear, tooth breakage, single pits, and distributed pitting were observed among the failed gears. Results show that the prediction methods were able to detect only those gear failures which involved heavy wear or distributed pitting. None of the methods could predict fatigue cracks, which resulted in tooth breakage, or single pits. It is suspected that the fatigue cracks were not detected because of limitations in data acquisition rather than in methodology. Additionally, the frequency response between the gear shaft and the transducer was found to significantly affect the vibration signal. The specific frequencies affected were filtered out of the signal average prior to application of the methods.

Zakrajsek, James J.

1989-01-01

316

The Numerical Analysis of a Turbulent Compressible Jet. Degree awarded by Ohio State Univ., 2000  

NASA Technical Reports Server (NTRS)

A numerical method to simulate high Reynolds number jet flows was formulated and applied to gain a better understanding of the flow physics. Large-eddy simulation was chosen as the most promising approach to model the turbulent structures due to its compromise between accuracy and computational expense. The filtered Navier-Stokes equations were developed including a total energy form of the energy equation. Subgrid scale models for the momentum and energy equations were adapted from compressible forms of Smagorinsky's original model. The effect of using disparate temporal and spatial accuracy in a numerical scheme was discovered through one-dimensional model problems and a new uniformly fourth-order accurate numerical method was developed. Results from two- and three-dimensional validation exercises show that the code accurately reproduces both viscous and inviscid flows. Numerous axisymmetric jet simulations were performed to investigate the effect of grid resolution, numerical scheme, exit boundary conditions and subgrid scale modeling on the solution and the results were used to guide the three-dimensional calculations. Three-dimensional calculations of a Mach 1.4 jet showed that this LES simulation accurately captures the physics of the turbulent flow. The agreement with experimental data was relatively good and is much better than results in the current literature. Turbulent intensities indicate that the turbulent structures at this level of modeling are not isotropic and this information could lend itself to the development of improved subgrid scale models for LES and turbulence models for RANS simulations. A two point correlation technique was used to quantify the turbulent structures. Two point space correlations were used to obtain a measure of the integral length scale, which proved to be approximately 1/2 D(sub j). Two point space-time correlations were used to obtain the convection velocity for the turbulent structures. This velocity ranged from 0.57 to 0.71 U(sub j).

DeBonis, James R.

2001-01-01

317

Dynamics of a class of vortex rings. Ph.D. Thesis - Stanford Univ.  

NASA Technical Reports Server (NTRS)

The contour dynamics method is extended to vortex rings with vorticity varying linearly from the symmetry axis. An elliptic core model is also developed to explain some of the basic physics. Passage and collisions of two identical rings are studied focusing on core deformation, sound generation and stirring of fluid elements. With respect to core deformation, not only the strain rate but how rapidly it varies is important and accounts for greater susceptibility to vortex tearing than in two dimensions. For slow strain, as a passage interaction is completed and the strain relaxes, the cores return to their original shape while permanent deformations remain for rapidly varying strain. For collisions, if the strain changes slowly the core shapes migrate through a known family of two-dimensional steady vortex pairs up to the limiting member of the family. Thereafter energy conservation does not allow the cores to maintain a constant shape. For rapidly varying strain, core deformation is severe and a head-tail structure in good agreement with experiments is formed. With respect to sound generation, good agreement with the measured acoustic signal for colliding rings is obtained and a feature previously thought to be due to viscous effects is shown to be an effect of inviscid core deformation alone. For passage interactions, a component of high frequency is present. Evidence for the importance of this noise source in jet noise spectra is provided. Finally, processes of fluid engulfment and rejection for an unsteady vortex ring are studied using the stable and unstable manifolds. The unstable manifold shows excellent agreement with flow visualization experiments for leapfrogging rings suggesting that it may be a good tool for numerical flow visualization in other time periodic flows.

Shariff, Karim; Leonard, Anthony; Ferziger, Joel H.

1989-01-01

318

Development of a grid-independent approximate Riemannsolver. Ph.D. Thesis - Michigan Univ.  

NASA Technical Reports Server (NTRS)

A grid-independent approximate Riemann solver for use with the Euler and Navier-Stokes equations was introduced and explored. The two-dimensional Euler and Navier-Stokes equations are described in Cartesian and generalized coordinates, as well as the traveling wave form of the Euler equations. The spatial and temporal discretization are described for both explicit and implicit time-marching schemes. The grid-aligned flux function of Roe is outlined, while the 5-wave grid-independent flux function is derived. The stability and monotonicity analysis of the 5-wave model are presented. Two-dimensional results are provided and extended to three dimensions. The corresponding results are presented.

Rumsey, Christopher Lockwood

1991-01-01

319

Robust fault diagnosis of physical systems in operation. Ph.D. Thesis - Rutgers - The State Univ.  

NASA Technical Reports Server (NTRS)

Ideas are presented and demonstrated for improved robustness in diagnostic problem solving of complex physical systems in operation, or operative diagnosis. The first idea is that graceful degradation can be viewed as reasoning at higher levels of abstraction whenever the more detailed levels proved to be incomplete or inadequate. A form of abstraction is defined that applies this view to the problem of diagnosis. In this form of abstraction, named status abstraction, two levels are defined. The lower level of abstraction corresponds to the level of detail at which most current knowledge-based diagnosis systems reason. At the higher level, a graph representation is presented that describes the real-world physical system. An incremental, constructive approach to manipulating this graph representation is demonstrated that supports certain characteristics of operative diagnosis. The suitability of this constructive approach is shown for diagnosing fault propagation behavior over time, and for sometimes diagnosing systems with feedback. A way is shown to represent different semantics in the same type of graph representation to characterize different types of fault propagation behavior. An approach is demonstrated that threats these different behaviors as different fault classes, and the approach moves to other classes when previous classes fail to generate suitable hypotheses. These ideas are implemented in a computer program named Draphys (Diagnostic Reasoning About Physical Systems) and demonstrated for the domain of inflight aircraft subsystems, specifically a propulsion system (containing two turbofan systems and a fuel system) and hydraulic subsystem.

Abbott, Kathy Hamilton

1991-01-01

320

Collider Physics: SDC/SSC liquified fiber calorimetry. [Physics Dept. , Texas A M Univ  

SciTech Connect

Most effort was directed toward the D-Zero experiment at Fermilab. Over 3 pb[sup [minus]1] of high-quality physics data have been obtained. Analysis of the results (wino-zino physics, squark physics), D-zero data acquisition systems efforts, and level-1 and level-2 trigger work are described. Other work concerned detector development for use at the SSC. This technology consists of using liquid scintillator-filled tubes as scintillating fibers for a calorimeter.'' The key issues were to demonstrate that the liquid fibers were sufficiently rad-hard and to demonstrate that fibers with sufficiently long attenuation length could be found to satisfy the resolution requirements; both constraints could be satisfied.

White, J.T.; Huson, F.R.

1992-01-01

321

Gravitational radiation theory. M.A. Thesis - Rice Univ.; [survey of current research  

NASA Technical Reports Server (NTRS)

A survey is presented of current research in the theory of gravitational radiation. The mathematical structure of gravitational radiation is stressed. Furthermore, the radiation problem is treated independently from other problems in gravitation. The development proceeds candidly through three points of view - scalar, rector, and tensor radiation theory - and the corresponding results are stated.

Wilson, T. L.

1973-01-01

322

Sounding rocket instrument development at Univ. of Alabama in Huntsville/NASA MSFC  

NASA Astrophysics Data System (ADS)

We present an overview of solar sounding rocket instruments developed jointly by NASA Marshall Space Flight Center and the University of Alabama in Huntsville. The High Resolution Coronal Imager (Hi-C) is an EUV (19.3 nm) imaging telescope which was flown successfully in July 2012. The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a Lyman Alpha (121.6 nm) spectropolarimeter developed jointly with the National Astronomical Observatory of Japan and scheduled for launch in 2015. The Marshall Grazing Incidence X-ray Spectrograph is a soft X-ray (0.5-1.2 keV) stigmatic spectrograph designed to achieve 5 arcsecond spatial resolution along the slit.

Kobayashi, Ken; Cirtain, Jonathan; Winebarger, Amy; Savage, Sabrina; Golub, Leon; Korreck, Kelly; Kuzin, Sergey; Walsh, Robert; DeForest, Craig; DePontieu, Bart; Title, Alan; Podgorski, William; Kano, Ryouhei; Narukage, Noriyuki; Trujillo-Bueno, Javier

2013-09-01

323

Pulmonary Edema and Plasma Volume Changes in Dysbarism. M.S. Thesis - Texas Univ.  

NASA Technical Reports Server (NTRS)

Two groups of anesthetized, fasted pigs were utilized. One group of 13 animals (8.5 to 16.6 kilograms) was exposed to a high-pressure environment, and the other group of eight animals (6.9 to 20.0 kilograms) constituted the control group. The experimental group was subjected to an atmosphere of 90 percent nitrogen and 10 percent oxygen at a pressure of 50 psig for 30 minutes and then decompressed at a rate 10 psi/min. Plasma volumes, using both iodine-125-tagged-albumin and chromium-51-tagged-cell dilution techniques, were measured before, immediately after, and at 30 and 60 minutes after decompression. Aortic and right-ventricular systolic pressures were also recorded. At 60 minutes after decompression, blood samples were taken, the animals were sacrificed, and the water content of the lungs, kidneys, livers, and spleens was estimated by measuring tissue wet weight and dry weight. Protein extravasation and tissue blood volumes were determined by measuring the iodine-125-tagged-albumin and chromium-51-tagged-cell spaces in homo-genates of the organs under investigation.

Joki, J. A.

1972-01-01

324

Faculty Development at the Dept. of Family Medicine Univ. of Western Ontario  

PubMed Central

The Department of Family Medicine at the University of Western Ontario has been in existence for ten years. During this time there has developed a wealth of experience in helping members of the Department, both fulltime and part-time, to improve their skills as family practice teachers. The current faculty development program has dealt with the transition period from practitioner to teacher, the interaction of teacher and student and current concepts of learning theory. It is now working on the development of scholarship within the department. An outline of the master of clinical science program is given. We hope this program will facilitate the successful development of the next generation of family medicine teachers.

Morrissy, J.R.; Biehn, J.T.; McWhinney, I.R.; Bass, M.J.

1977-01-01

325

Technical progress report, November 1, 1979-October 31, 1980. Report NPL-865. [Univ. of Colorado  

SciTech Connect

Work carried out at the Nuclear Physics Laboratory of the University of Colorado from November 1, 1979 through October 31, 1980 is summarized. Emphasis was on light ion reaction studies with the AVF cyclotron. The high resolution magnetic spectrometer has allowed studies of nucleon transfer, scattering, and charge exchange reactions throughout the periodic table. More experiments have been run with solid state counters this year than has been the case recently, as a broad range spectra of the light nuclei where only moderate resolution is demanded were examined. Several of these experiments were undertaken for more detailed studies of excitations seen with higher energy probes. Multiple coincidence measurements with neutron and gamma-ray counters have opened a new program in pre-equilibrium reactions and provided a new signature for the study of neutron-deficient final nuclei. The neutron time of flight program has expanded to higher excitation and to use of the (d,n) and (..cap alpha..,n) direct nucleon transfer reactions. Three important experiments were completed at the EPICS pion scattering facility at LAMPF, and other low energy pion scattering data were obtained at TRIUMF. Several (p,d) runs at high energies were accomplished, some with polarized beams at TRIUMF. High-lying structures in medium mass nuclei were studied by the (p,n) reaction at Indiana. Interest in the use of polarized beams has been prompted by the theoretical successes in this area. This interest has led to the study of one- and two-nucleon transfer reactions on a range of nuclei at the Los Alamos tandem and at IUCF.

Not Available

1980-11-01

326

Education Research and Teaching in Astrophysical & Planetary Sciences at the Univ. of Colorado  

NASA Astrophysics Data System (ADS)

The Department of Astrophysical and Planetary sciences at the University of Colorado has increasingly been incorporating research-based science education practices. The Colorado physics education research (PER) group is now one of the largest and most productive in the nation. It includes the work of Nobel laureate Carl Wieman's Science Education Initiative. Discipline-based education researchers in physics, astronomy, geology, and other departments meet weekly. Like physics, essentially all large courses in Astrophysical and Planetary Sciences are now taught using peer instruction and "clickers." Approximately 17,000 clickers are in use at CU. A new diagnostic instrument whose subject is (modern) solar system astronomy has been developed and is available for testing. The first-ever departmental Ph.D. in astronomy education research (AER) is under way. A curriculum that encourages students to use more scientific thinking in everyday life and to distinguish good science from bad has been successfully tested. It can be used as part of any introductory geology or astronomy course. Two faculty members are conducting AER, supported by NSF Grant No. 0715517, a CCLI Phase III Grant for the Collaboration of Astronomy Teaching Scholars (CATS) Program. Neither of these two faculty members are in tenure-track lines.

Duncan, D. K.; Arthurs, L.

2009-12-01

327

Estimation from incomplete multinomial data. Ph.D. Thesis - Harvard Univ.  

NASA Technical Reports Server (NTRS)

The vector of multinomial cell probabilities was estimated from incomplete data, incomplete in that it contains partially classified observations. Each such partially classified observation was observed to fall in one of two or more selected categories but was not classified further into a single category. The data were assumed to be incomplete at random. The estimation criterion was minimization of risk for quadratic loss. The estimators were the classical maximum likelihood estimate, the Bayesian posterior mode, and the posterior mean. An approximation was developed for the posterior mean. The Dirichlet, the conjugate prior for the multinomial distribution, was assumed for the prior distribution.

Credeur, K. R.

1978-01-01

328

Arctic lidar at Univ. of California/Los Angeles' HIPAS Observatory  

NASA Astrophysics Data System (ADS)

A bistatic lidar has been assembled at the HIPAS Observatory in Alaska (64.9 degree(s) N latitude and 146.8 degree(s) W) around a 2.7 m diameter rotating Liquid Mirror Telescope (LMT) with parabolic mercury reflecting surface. The LMT is isolated in a tower under a float glass skylight for operation when outside temperature can be at -40 degree(s)C. The lidar operates in conjunction with a 70MW (Effective Radiated Power) Radio Frequency array and ionospheric heater, which has been shown to perturb the arctic ionosphere and the electrojet. Bistatic laser illuminators include a Doubled YAG pumped dye laser (presently tuned to the 590 nm sodium D2 resonance), an Excimer pumped dye laser (also tuned to the D2 line), and a Doubled Alexandrite laser for future N2 and Ca+ detection. Observations include sporadic Na formation due to the aurora, detection of Leonid's meteor trails (starting at 180 km) and changes in the sodium layer due to the HIPAS-RF heater. The 590 nm lidar is now being modified to detect polar stratospheric clouds during the summer. Ozone and OH can be detected in the future with the 308 nm wavelength of the excimer laser. A more recent application will use the LMT to focus a several hundred Joule - nanosecond duration laser pulse to 100 km altitudes, for the purpose of creating multi kilometer long plasma columns in the sky for direct electroject modification experiments. The 1057 nm laser pulse will be generated by surplus Nova components; namely, 9.2 cm and 15 cm disk amplifiers in a double pass SBS configuration.

Wuerker, Ralph F.

2002-01-01

329

PLUM: Parallel Load Balancing for Unstructured Adaptive Meshes. Degree awarded by Colorado Univ.  

NASA Technical Reports Server (NTRS)

Dynamic mesh adaption on unstructured grids is a powerful tool for computing large-scale problems that require grid modifications to efficiently resolve solution features. By locally refining and coarsening the mesh to capture physical phenomena of interest, such procedures make standard computational methods more cost effective. Unfortunately, an efficient parallel implementation of these adaptive methods is rather difficult to achieve, primarily due to the load imbalance created by the dynamically-changing nonuniform grid. This requires significant communication at runtime, leading to idle processors and adversely affecting the total execution time. Nonetheless, it is generally thought that unstructured adaptive- grid techniques will constitute a significant fraction of future high-performance supercomputing. Various dynamic load balancing methods have been reported to date; however, most of them either lack a global view of loads across processors or do not apply their techniques to realistic large-scale applications.

Oliker, Leonid

1998-01-01

330

Stability of large horizontal-axis axisymmetric wind turbines. Ph.D. Thesis - Delaware Univ.  

NASA Technical Reports Server (NTRS)

The stability of large horizontal axis, axi-symmetric, power producing wind turbines was examined. The analytical model used included the dynamic coupling of the rotor, tower and power generating system. The aerodynamic loading was derived from blade element theory. Each rotor blade was permitted tow principal elastic bending degrees of freedom, one degree of freedom in torsion and controlled pitch as a rigid body. The rotor hub was mounted in a rigid nacelle which may yaw freely or in a controlled manner. The tower can bend in two principal directions and may twist. Also, the rotor speed can vary and may induce perturbation reactions within the power generating equipment. Stability was determined by the eigenvalues of a set of linearized constant coefficient differential equations. All results presented are based on a 3 bladed, 300 ft. diameter, 2.5 megawatt wind turbine. Some of the parameters varied were; wind speed, rotor speed structural stiffness and damping, the effective stiffness and damping of the power generating system and the principal bending directions of the rotor blades. Unstable or weakly stable behavior can be caused by aerodynamic forces due to motion of the rotor blades and tower in the plane of rotation or by mechanical coupling between the rotor system and the tower.

Hirschbein, M. S.; Young, M. I.

1980-01-01

331

[Electron transfer, ionization, and excitation in atomic collisions]. [Pennsylvania State Univ  

SciTech Connect

Fundamental processes of electron transfer, ionization, and excitation in ion-atom and ion-ion collisions are studied. Attention is focussed on one- and two-electron systems and, more recently, quasi-one-electron systems whose electron-target-ion core can be accurately modeled by one-electron potentials. The basic computational approaches can then be taken with few, if any, approximations, and the underlying collisional mechanisms can be more clearly revealed. At intermediate collision energies (e.g., proton energies for p-He[sup +] collisions on the order of 100 kilo-electron volts), many electronic states are strongly coupled during the collision, a coupled-state approach, such as a coupled-Sturmian-pseudostate approach, is appropriate. At higher collision energies (million electron-volt energies) the coupling is weaker with, however, many more states being coupled together, so that high-order perturbation theory is essential.

Not Available

1992-01-01

332

Numerical simulation of separated flows. Ph.D. Thesis - Stanford Univ., Calif.  

NASA Technical Reports Server (NTRS)

A new numerical method, based on the Vortex Method, for the simulation of two-dimensional separated flows, was developed and tested on a wide range of gases. The fluid is incompressible and the Reynolds number is high. A rigorous analytical basis for the representation of the Navier-Stokes equation in terms of the vorticity is used. An equation for the control of circulation around each body is included. An inviscid outer flow (computed by the Vortex Method) was coupled with a viscous boundary layer flow (computed by an Eulerian method). This version of the Vortex Method treats bodies of arbitrary shape, and accurately computes the pressure and shear stress at the solid boundary. These two quantities reflect the structure of the boundary layer. Several versions of the method are presented and applied to various problems, most of which have massive separation. Comparison of its results with other results, generally experimental, demonstrates the reliability and the general accuracy of the new method, with little dependence on empirical parameters. Many of the complex features of the flow past a circular cylinder, over a wide range of Reynolds numbers, are correctly reproduced.

Spalart, P. R.; Leonard, A.; Baganoff, D.

1983-01-01

333

Photogrammetry and Videogrammetry Methods Development for Solar Sail Structures. Masters Thesis awarded by George Washington Univ.  

NASA Technical Reports Server (NTRS)

This report discusses the development and application of metrology methods called photogrammetry and videogrammetry that make accurate measurements from photographs. These methods have been adapted for the static and dynamic characterization of gossamer structures, as four specific solar sail applications demonstrate. The applications prove that high-resolution, full-field, non-contact static measurements of solar sails using dot projection photogrammetry are possible as well as full-field, non-contact, dynamic characterization using dot projection videogrammetry. The accuracy of the measurement of the resonant frequencies and operating deflection shapes that were extracted surpassed expectations. While other non-contact measurement methods exist, they are not full-field and require significantly more time to take data.

Pappa, Richard S. (Technical Monitor); Black, Jonathan T.

2003-01-01

334

Final Report on Grant N00014-88-K-0425 (California Univ).  

National Technical Information Service (NTIS)

We summarize advances in the general understanding of strong plasma turbulence, with special application to the mechanisms for powerful microwave emission. Principally, we developed an optical diagnostic system which permits simultaneous measures of the t...

G. Benford

1989-01-01

335

A Marriage of Minds: James R. Jacobs & Shinjoung Yeo Univ. of California-San Diego  

ERIC Educational Resources Information Center

Their personalities and backgrounds are very different, but James R. Jacobs and Shinjoung Yeo are passionate about the same causes: librarianship, open government, and empowerment through information. They balance each other. Yeo is focused, realistic, critical, and an excellent researcher. Her superhero alter ego is Wet Blanket Woman, able to…

Library Journal, 2005

2005-01-01

336

Elastohydrodynamic lubrication of point contacts. Ph.D. Thesis - Leeds Univ.  

NASA Technical Reports Server (NTRS)

A procedure for the numerical solution of the complete, isothermal, elastohydrodynamic lubrication problem for point contacts is given. This procedure calls for the simultaneous solution of the elasticity and Reynolds equations. By using this theory the influence of the ellipticity parameter and the dimensionless speed, load, and material parameters on the minimum and central film thicknesses was investigated. Thirty-four different cases were used in obtaining the fully flooded minimum- and central-film-thickness formulas. Lubricant starvation was also studied. From the results it was possible to express the minimum film thickness for a starved condition in terms of the minimum film thickness for a fully flooded condition, the speed parameter, and the inlet distance. Fifteen additional cases plus three fully flooded cases were used in obtaining this formula. Contour plots of pressure and film thickness in and around the contact have been presented for both fully flooded and starved lubrication conditions.

Hamrock, B. J.

1976-01-01

337

Direct simulation Monte Carlo with ionization and radiation. Ph.D. Thesis, North Carolina State Univ.  

NASA Technical Reports Server (NTRS)

Improvements in the modeling of radiation in low density shock waves with Direct Simulation Monte Carlo (DSMC) are the subject of this study. The physical processes which determine the amount of radiation in a shock wave were investigated and the way in which they were modeled with DSMC was evaluated. Three physical processes were identified for which an improvement in the modeling technique could result in improved radiation predictions. New physical modeling schemes are introduced in this report for the three processes. First a method for determining the electric field and its effect on the flow is introduced. Second, a two step reaction process for electron impact ionization reactions is evaluated. Finally, a new scheme to determine the relaxation collision numbers for excitation of electronic states is proposed. Each new scheme attempts to move the DSMC method toward more accurate physics or more reliance on experimental data. The new schemes are all compared to the current modeling techniques and the differences in the results are evaluated. In all cases the results agree with the available data as well as, or better than the results from earlier schemes.

Carlson, Ann B.

1990-01-01

338

Optical measurements of soot in premixed flames. Ph.D. Thesis - California Univ.  

NASA Technical Reports Server (NTRS)

Two laser diagnostic techniques were used to measure soot volume fractions, number densities and soot particle radii in premixed propane/oxygen flat flames. The two techniques were two wavelength extinction, using 514.5 to 632.8 nm and 457.9 to 632.8 nm wavelength combinations, and extinction/scattering using 514.5 nm light. The flames were fuel rich and had cold gas velocities varying from 3.4 to 5.5 cm/s. Measurements were made at various heights above the sintered bronze, water colored flat flame burner with the equivalence ratio and cold gas velocity fixed. Also, measurements were made at a fixed height above the burner and fixed cold gas velocity while varying the equivalence ratio. Both laser techniques are based on the same underlying assumptions of particle size distribution and soot optical properties. Full Mie theory was used to determine the extinction coefficients and the scattering efficiencies. Temperature measurements in the flame were made using infrared radiometry and fine wire thermocouples. Good agreement between the two techniques in terms of soot particle radii, number density and volume fraction was found for intensity ratios between 0.1 and 0.8.

Lyons, Valerie J.

1988-01-01

339

General Theory of the Double Fed Synchronous Machine. Ph.D. Thesis - Swiss Technological Univ., 1950  

NASA Technical Reports Server (NTRS)

Motor and generator operation of a double-fed synchronous machine were studied and physically and mathematically treated. Experiments with different connections, voltages, etc. were carried out. It was concluded that a certain degree of asymmetry is necessary for the best utilization of the machine.

El-Magrabi, M. G.

1982-01-01

340

Dynamics of a split torque helicopter transmission. M.S. Thesis - Cleveland State Univ.  

NASA Technical Reports Server (NTRS)

Split torque designs, proposed as alternatives to traditional planetary designs for helicopter main rotor transmissions, can save weight and be more reliable than traditional designs. This report presents the results of an analytical study of the system dynamics and performance of a split torque gearbox that uses a balance beam mechanism for load sharing. The Lagrange method was applied to develop a system of equations of motion. The mathematical model includes time-varying gear mesh stiffness, friction, and manufacturing errors. Cornell's method for calculating the stiffness of spur gear teeth was extended and applied to helical gears. The phenomenon of sidebands spaced at shaft frequencies about gear mesh fundamental frequencies was simulated by modeling total composite gear errors as sinusoid functions. Although the gearbox has symmetric geometry, the loads and motions of the two power paths differ. Friction must be considered to properly evaluate the balance beam mechanism. For the design studied, the balance beam is not an effective device for load sharing unless the coefficient of friction is less than 0.003. The complete system stiffness as represented by the stiffness matrix used in this analysis must be considered to precisely determine the optimal tooth indexing position.

Krantz, Timothy L.

1994-01-01

341

A numerical study of fundamental shock noise mechanisms. Ph.D. Thesis - Cornell Univ.  

NASA Technical Reports Server (NTRS)

The results of this thesis demonstrate that direct numerical simulation can predict sound generation in unsteady aerodynamic flows containing shock waves. Shock waves can be significant sources of sound in high speed jet flows, on helicopter blades, and in supersonic combustion inlets. Direct computation of sound permits the prediction of noise levels in the preliminary design stage and can be used as a tool to focus experimental studies, thereby reducing cost and increasing the probability of a successfully quiet product in less time. This thesis reveals and investigates two mechanisms fundamental to sound generation by shocked flows: shock motion and shock deformation. Shock motion is modeled by the interaction of a sound wave with a shock. During the interaction, the shock wave begins to move and the sound pressure is amplified as the wave passes through the shock. The numerical approach presented in this thesis is validated by the comparison of results obtained in a quasi-one dimensional simulation with linear theory. Analysis of the perturbation energy demonstrated for the first time that acoustic energy is generated by the interaction. Shock deformation is investigated by the numerical simulation of a ring vortex interacting with a shock. This interaction models the passage of turbulent structures through the shock wave. The simulation demonstrates that both acoustic waves and contact surfaces are generated downstream during the interaction. Analysis demonstrates that the acoustic wave spreads cylindrically, that the sound intensity is highly directional, and that the sound pressure level increases significantly with increasing shock strength. The effect of shock strength on sound pressure level is consistent with experimental observations of shock noise, indicating that the interaction of a ring vortex with a shock wave correctly models a dominant mechanism of shock noise generation.

Meadows, Kristine R.

1995-01-01

342

An Analysis of NASA Technology Transfer. Degree awarded by Pennsylvania State Univ.  

NASA Technical Reports Server (NTRS)

A review of previous technology transfer metrics, recommendations, and measurements is presented within the paper. A quantitative and qualitative analysis of NASA's technology transfer efforts is performed. As a relative indicator, NASA's intellectual property performance is benchmarked against a database of over 100 universities. Successful technology transfer (commercial sales, production savings, etc.) cases were tracked backwards through their history to identify the key critical elements that lead to success. Results of this research indicate that although NASA's performance is not measured well by quantitative values (intellectual property stream data), it has a net positive impact on the private sector economy. Policy recommendations are made regarding technology transfer within the context of the documented technology transfer policies since the framing of the Constitution. In the second thrust of this study, researchers at NASA Langley Research Center were surveyed to determine their awareness of, attitude toward, and perception about technology transfer. Results indicate that although researchers believe technology transfer to be a mission of the Agency, they should not be held accountable or responsible for its performance. In addition, the researchers are not well educated about the mechanisms to perform, or policies regarding, technology transfer.

Bush, Lance B.

1996-01-01

343

Line-blanketed model stellar atmospheres applied to Sirius. Ph.D. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

The primary goal of this analysis is to determine whether the effects of atomic bound-bound transitions on stellar atmospheric structure can be represented well in models. The investigation is based on an approach which is called the method of artificial absorption edges. The method is described, developed, tested, and applied to the problem of fitting a model stellar atmosphere to Sirius. It is shown that the main features of the entire observed spectrum of Sirius can be reproduced to within the observational uncertainty by a blanketed flux-constant model with T sub eff = 9700 K and Log g = 4.26. The profile of H sub gamma is reproduced completely within the standard deviations of the measurements except near line center, where non-LTE effects are expected to be significant. The equivalent width of H sub gamma, the Paschen slope, the Balmer jump, and the absolute flux at 5550 A all agree with the observed values.

Fowler, J. W.

1972-01-01

344

Early impact basins and the onset of plate tectonics. Ph.D. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

The fundamental crustal dichotomy of the Earth (high and low density crust) was established nearly 4 billion years ago. Therefore, subductable crust was concentrated at the surface of the Earth very early in its history, making possible an early onset for plate tectonics. Simple thermal history calculations spanning 1 billion years show that the basin forming impact thins the lithosphere by at least 25%, and increases the sublithosphere thermal gradients by roughly 20%. The corresponding increase in convective heat transport, combined with the highly fractured nature of the thinned basin lithosphere, suggest that lithospheric breakup or rifting occurred shortly after the formation of the basins. Conditions appropriate for early rifting persisted from some 100,000,000 years following impact. We suggest a very early stage of high temperature, fast spreading "microplate" tectonics, originating before 3.5 billion years ago, and gradually stabilizing over the Archaean into more modern large plate or Wilson Cycle tectonics.

Frey, H.

1977-01-01

345

Topics in Astrophysical X-Ray and Gamma Ray Spectroscopy. Ph.D. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

A number of topics relating to astrophysical observations that have already been made or are currently planned of spectral features, mostly emission lines, in the X-ray and gamma ray region of the electromagnetic spectrum are investigated. These topics include: the production of characteristic X-ray and gamma ray lines by nonthermal ions, spectral features induced by processes occurring in strong magnetic fields, and the positron annihilation line at 0.5 MeV. The rate of X-ray production at 6.8 keV by the 2p to 1s transition in fast hydrogen- and helium-like iron ions, following both electron capture to excited levels and collisional excitation is calculated. The cross section for electron-ion Coulomb collisions in strong fields is also calculated.

Bussard, R. W.

1978-01-01

346

Residual Stress Reversal in Highly Strained Shot Peened Structural Elements. Degree awarded by Florida Univ.  

NASA Technical Reports Server (NTRS)

The purpose of this research was to further the understanding of a crack initiation problem in a highly strained pressure containment housing. Finite Element Analysis methods were used to model the behavior of shot peened materials undergoing plastic deformation. Analytical results are in agreement with laboratory tensile tests that simulated the actual housing load conditions. These results further validate the original investigation finding that the shot peened residual stress had reversed, changing from compressive to tensile, and demonstrate that analytical finite element methods can be used to predict this behavior.

Mitchell, William S.; Throckmorton, David (Technical Monitor)

2002-01-01

347

Advanced propulsion for LEO-Moon transport. 3: Transportation model. M.S. Thesis - California Univ.  

NASA Technical Reports Server (NTRS)

A simplified computational model of low Earth orbit-Moon transportation system has been developed to provide insight into the benefits of new transportation technologies. A reference transportation infrastructure, based upon near-term technology developments, is used as a departure point for assessing other, more advanced alternatives. Comparison of the benefits of technology application, measured in terms of a mass payback ratio, suggests that several of the advanced technology alternatives could substantially improve the efficiency of low Earth orbit-Moon transportation.

Henley, Mark W.

1992-01-01

348

Generalized Reliability Methodology Applied to Brittle Anisotropic Single Crystals. Degree awarded by Washington Univ., 1999  

NASA Technical Reports Server (NTRS)

A generalized reliability model was developed for use in the design of structural components made from brittle, homogeneous anisotropic materials such as single crystals. The model is based on the Weibull distribution and incorporates a variable strength distribution and any equivalent stress failure criteria. In addition to the reliability model, an energy based failure criterion for elastically anisotropic materials was formulated. The model is different from typical Weibull-based models in that it accounts for strength anisotropy arising from fracture toughness anisotropy and thereby allows for strength and reliability predictions of brittle, anisotropic single crystals subjected to multiaxial stresses. The model is also applicable to elastically isotropic materials exhibiting strength anisotropy due to an anisotropic distribution of flaws. In order to develop and experimentally verify the model, the uniaxial and biaxial strengths of a single crystal nickel aluminide were measured. The uniaxial strengths of the <100> and <110> crystal directions were measured in three and four-point flexure. The biaxial strength was measured by subjecting <100> plates to a uniform pressure in a test apparatus that was developed and experimentally verified. The biaxial strengths of the single crystal plates were estimated by extending and verifying the displacement solution for a circular, anisotropic plate to the case of a variable radius and thickness. The best correlation between the experimental strength data and the model predictions occurred when an anisotropic stress analysis was combined with the normal stress criterion and the strength parameters associated with the <110> crystal direction.

Salem, Jonathan A.

2002-01-01

349

Finite Element A Posteriori Error Estimation for Heat Conduction. Degree awarded by George Washington Univ.  

NASA Technical Reports Server (NTRS)

This research investigates residual-based a posteriori error estimates for finite element approximations of heat conduction in single-layer and multi-layered materials. The finite element approximation, based upon hierarchical modelling combined with p-version finite elements, is described with specific application to a two-dimensional, steady state, heat-conduction problem. Element error indicators are determined by solving an element equation for the error with the element residual as a source, and a global error estimate in the energy norm is computed by collecting the element contributions. Numerical results of the performance of the error estimate are presented by comparisons to the actual error. Two methods are discussed and compared for approximating the element boundary flux. The equilibrated flux method provides more accurate results for estimating the error than the average flux method. The error estimation is applied to multi-layered materials with a modification to the equilibrated flux method to approximate the discontinuous flux along a boundary at the material interfaces. A directional error indicator is developed which distinguishes between the hierarchical modeling error and the finite element error. Numerical results are presented for single-layered materials which show that the directional indicators accurately determine which contribution to the total error dominates.

Lang, Christapher G.; Bey, Kim S. (Technical Monitor)

2002-01-01

350

On the Physical Environment in the Galactic Nuclei. Ph.D. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

Galactic nuclei and quasars emit radiation over the entire electromagnetic spectrum. This suggests that concurrent observations over a wide frequency range may provide useful information in determining appropriate models for the physical environment in which the radiation is produced. In conjunction with observations by the high energy spectrometer on OSO-8, four sources have been studied in this manner; the nucleus of the elliptical galaxy, Centaurus A (NGG 5128); the quasar, 30273; the Seyfert galaxy, NGC 4151 and the nucleus of the Milky Way (GCX). Concurrent observations are used to construct the composite spectra (from radio to X-ray) for Cen A and NGC 4151 while the composite spectra of 30273 and GCX are derived from the OSO-8 data and from other observers. A skymap technique used to analyze observations of the galactic center region yielded data consistent with a significant, hard X-ray source at the radio and infrared position of the nucleus of the Milky Way. A theoretical analysis of the temporal variability of the Cen A data is undertaken and its implications discussed. Similarities between the composite spectra of the observed sources suggest that radio-bright and radio-quiet quasars may represent the emission from galactic nuclei with elliptical and Seyfert-like morphologies, respectively.

Beall, J. H.

1979-01-01

351

Analysis of pressure spectra measurements in a ducted combustion system. Ph.D. Thesis - Toledo Univ.  

NASA Technical Reports Server (NTRS)

Combustion noise propagation in an operating ducted liquid fuel combustion system is studied in relation to the development of combustion noise prediction and suppression techniques. The presence of combustor emissions in the duct is proposed as the primary mechanism producing the attenuation and dispersion of combustion noise propagating in an operating liquid fuel combustion system. First, a complex mathematical model for calculating attenuation and dispersion taking into account mass transfer, heat transfer, and viscosity effects due to the presence of liquid fuel droplets or solid soot particles is discussed. Next, a simpler single parameter model for calculating pressure auto-spectra and cross-spectra which takes into account dispersion and attenuation due to heat transfer between solid soot particles and air is developed. Then, auto-spectra and cross-spectra obtained from internal pressure measurements in a combustion system consisting of a J-47 combustor can, a spool piece, and a long duct are presented. Last, analytical results obtained with the single parameter model are compared with the experimental measurements. The single parameter model results are shown to be in excellent agreement with the measurements.

Miles, J. H.

1980-01-01

352

The shock process and light element production in supernovae envelopes. Ph.D. Thesis - Chicago Univ.  

NASA Technical Reports Server (NTRS)

Detailed hydrodynamic modeling of the passage of supernova shocks through the hydrogen envelopes of blue and red progenitor stars was carried out to explore the sensitivity to model conditions of light element production (specifically Li-7 and B-11) which was noted by Dearborn, Schramm, Steigman and Truran (1989) (DSST). It is found that, for stellar models with M is less than or approximately 100 M solar mass, current state of the art supernova shocks do not produce significant light element yields by hydrodynamic processes alone. The dependence of this conclusion on stellar models and on shock strengths is explored. Preliminary implications for Galactic evolution of lithium are discussed, and it is suspected that intermediate mass red giant stars may be the most consistent production site for lithium.

Brown, Lawrence E.; Dearborn, David S.; Schramm, David N.; Larsen, Jon T.; Kurokawa, Shin

1990-01-01

353

Vehicle integration effects on hypersonic waveriders. M.S. Thesis - George Washington Univ.  

NASA Technical Reports Server (NTRS)

The integration of a class of hypersonic high-lift configurations known as waveriders into hypersonic cruise vehicles was evaluated. Waveriders offer advantages in aerodynamic performance and propulsion/airframe integration (PAI) characteristics over conventional hypersonic shapes. A wind-tunnel model was developed which integrates realistic vehicle components with two waverider shapes, referred to as the 'straight-wing' and 'cranked-wing' shapes. Both shapes were conical-flow-derived waveriders at a design Mach number of 4.0. The cranked-wing shape was designed to provide advantages in subsonic performance and directional stability over conventional waveriders. Experimental data and limited computational fluid dynamics (CFD) predictions were obtained over a Mach number range of 2.3 to 4.63 at a Reynolds number of 2.0x10(exp 6) per foot. The CFD predictions and flow visualization data confirmed the shock attachment characteristics of the baseline waverider shapes and illustrated the waverider flow-field properties. Both CFD predictions and experimental data showed that no significant performance degradations occur at off-design Mach numbers for the waverider shapes and the integrated configurations. The experimental data showed that the effects of adding a realistic canopy were minimal. The effects of adding engine components were to increase the drag and thus degrade the aerodynamic performance of the configuration. A significant degradation in aerodynamic performance was observed when 0 degree control surfaces were added to close the blunt base of the waverider to a sharp trailing edge. A comparison of the fully-integrated waverider models to the baseline shapes showed that the performance was significantly degraded when all of the components were added to the waveriders. The fully-integrated configurations studied here do not offer significant performance advantages over conventional hypersonic vehicles, but still offer advantages in air-breathing propulsion integration. Additionally, areas are identified in this study where improvements could be made to enhance the performance. Both fully-integrated configurations are longitudinally unstable over the Mach number range studied for unpowered conditions. The cranked-wing fully-integrated configuration provided significantly better lateral-directional stability characteristics than the straight-wing configuration.

Cockrell, Charles Edward, Jr.

1994-01-01

354

Using UPLC-QTOF-MS to analyze the chemical changes between traditional and dispensing granule decoctions of San-Ao-Tang.  

PubMed

In the present study, a chemical profiling approach based on ultra-performance liquid chromatography coupled with photodiode array detection and time-of-flight mass spectrometry (UPLC-PDA-TOF-MS) was proposed to rapidly evaluate the chemical consistency between traditional and dispensing granule decoctions of traditional medicine combinatorial formulae and validated using San-Ao-Tang (SAT) as a model combinatorial formula. SAT is an effective traditional Chinese medicine, which is usually used in treating asthma and other diseases of the respiratory system. Two decoctions were prepared: traditional decoction, which is a water extract of three mixed constituent herbs of SAT; and dispensing granule decoction, which is a mixed water extract of each individual herb of SAT. Batches of these two decoction samples were subjected to UPLC-PDA-TOF-MS analysis and the data sets of t(R)-m/z pairs, ion intensities and sample codes were processed with supervised orthogonal partial least squared discriminant analysis to holistically compare their differences. Once a clear classification trend was found in the score plot, further statistics were performed to generate points at the two ends of S, and the components that correlated to these ions were regarded as the most changed components during decoction of the combinatorial formula. The changed components were identified by comparing the mass/ultraviolet spectra and retention times with those of reference compounds and/or tentatively assigned by matching empirical molecular formulae with those of the known compounds published in the literature. Using the proposed approach, global chemical differences were found between traditional and dispensing granule decoctions, like ephedrine, pseudoephedrine, norpseudoephedrine, licorice saponine H2, licorice saponine G2 and amygdalin. PMID:23572319

Ma, Chunhua; Qian, Yefei; Fan, Xinsheng; Shang, ErXin; Yao, Xin; Ma, Shiping

2014-04-01

355

Temperature dependence of alkali-metal rattling dynamics in the ?-pyrochlores, AOs2O6 (A = K, Rb, Cs), from MD simulation  

NASA Astrophysics Data System (ADS)

We investigate the temperature response of the alkali-metal rattling modes in ?-pyrochlores, AOs2O6 (A = K, Rb, Cs), from the results of ab initio molecular dynamics (MD) simulations performed at 20?K, 100?K and 300?K. Our results show that the temperature response of the T1u mode is clearly different from that of the T2g mode for all three pyrochlores. In this regard, two features are of particular note for both K and Rb; (1) the T1u mode exhibits a distinctly stronger softening response with decreasing temperature compared to the T2g mode, and (2) the T1u mode becomes stronger and sharper with decreasing temperature. These two findings suggest that the T1u mode is significantly more anharmonic and sensitive to the cage dynamics than the T2g mode. Examination of the local potentials around the alkali-metal atoms reveals that K has the flattest and most anharmonic potential at all temperatures while Cs exhibits the narrowest potential. The temperature dependence of the local potentials reveals that, for K, the potential at a higher temperature is not a simple extrapolation to higher energy of that at a lower temperature. Instead, we find significant reconstruction of the potential at different temperatures. Finally, we explore the temperature response of the coupling between the alkali metals and find a complex temperature dependence which suggests that the origin of the coupling may be more complex than a pure Coulomb interaction. We also find an unexpected increase in the static disorder of the system at low temperatures for the K and Rb pyrochlores.

Shoko, E.; Peterson, V. K.; Kearley, G. J.

2014-06-01

356

Temperature dependence of alkali-metal rattling dynamics in the ?-pyrochlores, AOs2O6 (A = K, Rb, Cs), from MD simulation.  

PubMed

We investigate the temperature response of the alkali-metal rattling modes in ?-pyrochlores, AOs2O6 (A = K, Rb, Cs), from the results of ab initio molecular dynamics (MD) simulations performed at 20?K, 100?K and 300?K. Our results show that the temperature response of the T1u mode is clearly different from that of the T2g mode for all three pyrochlores. In this regard, two features are of particular note for both K and Rb; (1) the T1u mode exhibits a distinctly stronger softening response with decreasing temperature compared to the T2g mode, and (2) the T1u mode becomes stronger and sharper with decreasing temperature. These two findings suggest that the T1u mode is significantly more anharmonic and sensitive to the cage dynamics than the T2g mode. Examination of the local potentials around the alkali-metal atoms reveals that K has the flattest and most anharmonic potential at all temperatures while Cs exhibits the narrowest potential. The temperature dependence of the local potentials reveals that, for K, the potential at a higher temperature is not a simple extrapolation to higher energy of that at a lower temperature. Instead, we find significant reconstruction of the potential at different temperatures. Finally, we explore the temperature response of the coupling between the alkali metals and find a complex temperature dependence which suggests that the origin of the coupling may be more complex than a pure Coulomb interaction. We also find an unexpected increase in the static disorder of the system at low temperatures for the K and Rb pyrochlores. PMID:24832480

Shoko, E; Peterson, V K; Kearley, G J

2014-06-11

357

ON THE LOCATION OF THE {gamma}-RAY OUTBURST EMISSION IN THE BL LACERTAE OBJECT AO 0235+164 THROUGH OBSERVATIONS ACROSS THE ELECTROMAGNETIC SPECTRUM  

SciTech Connect

We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and {gamma}-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array images at {lambda} = 7 mm with {approx}0.15 milliarcsec resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary 'core' and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long timescales (months/years), but the correspondence is poorer on shorter timescales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.

Agudo, Ivan; Gomez, Jose L. [Instituto de Astrofisica de Andalucia, CSIC, Apartado 3004, 18080 Granada (Spain); Marscher, Alan P.; Jorstad, Svetlana G. [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Larionov, Valeri M.; Blinov, Dmitriy A.; Hagen-Thorn, Vladimir A. [Astronomical Institute, St. Petersburg State University, Universitetskij Pr. 28, Petrodvorets, 198504 St. Petersburg (Russian Federation); Laehteenmaeki, Anne [Aalto University Metsaehovi Radio Observatory, Metsaehovintie 114, FIN-02540 Kylmaelae (Finland); Smith, Paul S. [Steward Observatory, University of Arizona, Tucson, AZ 85721-0065 (United States); Nilsson, Kari [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaeisaelaentie 20, FIN-21500 Piikkioe (Finland); Readhead, Anthony C. S. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Mail Code 222, Pasadena, CA 91125 (United States); Aller, Margo F.; Aller, Hugh D. [Department of Astronomy, University of Michigan, 817 Dennison Building, Ann Arbor, MI 48 109 (United States); Heidt, Jochen [ZAH, Landessternwarte Heidelberg, Koenigstuhl, 69117 Heidelberg (Germany); Gurwell, Mark [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Thum, Clemens [Institut de Radio Astronomie Millimetrique, 300 Rue de la Piscine, 38406 St. Martin d'Heres (France); Wehrle, Ann E. [Space Science Institute, Boulder, CO 80301 (United States); Nikolashvili, Maria G. [Abastumani Observatory, Mt. Kanobili, 0301 Abastumani, Georgia (United States); BenItez, Erika [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, 04510 Mexico D. F. (Mexico); Hiriart, David, E-mail: iagudo@iaa.es [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, 2280 Ensenada (Mexico)

2011-07-01

358

On the Location of the gamma-Ray Outburst Emission in the BL Lacertae Object AO 0235 + 164 Through Observations Across the Electromagnetic Spectrum  

NASA Technical Reports Server (NTRS)

We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array images at A = 7 mm with approx.0.15 milliarcsec resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long timescales (months/ years), but the correspondence is poorer on shorter timescales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.

Agudo, Ivan; Marscher, Alan P.; Jorstad, Svetlana G.; Larionov, Valeri M.; Gomez, Jose L.; Laehteenmaeki, Anne; Smith, Paul S.; Nilsson, Kari; Readhead, Anthony C. S.; Aller, Margo F.; Heidt, Jochien; Gurwell, Mark; Thum, Clemens; Wehrle, Ann E.; Nikolashvili, Maria G.; Aller, Hugh D.; Benitez, Erika; Blinov, Dmitriy A.; Hagen-Thorn, Vladimir A.; Hiriart, David; Jannuzi, Buell T.; Joshi, Manasvita; Kimeridze, Givi N.; Kurtanidze, Omar M.; Kurtanidze, Sofia O.

2011-01-01

359

The mass of the black hole in Centaurus A from SINFONI AO-assisted integral-field observations of stellar kinematics  

NASA Astrophysics Data System (ADS)

We present a determination of the mass of the supermassive black hole (BH) and the nuclear stellar orbital distribution of the elliptical galaxy Centaurus A (Cen A) (NGC 5128) using high-resolution integral-field observations of the stellar kinematics. The observations were obtained with SINFONI (Spectrograph for INtegral Field Observations in the Near Infrared) at the European Southern Observatory Very Large Telescope in the near-infrared (IR) (K band), using adaptive optics (AO) to correct for the blurring effect of the Earth's atmosphere. The data have a spatial resolution of 0.17 arcsec full width at half-maximum and high signal-to-noise ratios (S/N) >~ 80 per spectral pixel so that the shape of the stellar line-of-sight velocity distribution can be reliably extracted. We detect clear low-level stellar rotation, which is counter-rotating with respect to the gas. We fit axisymmetric three-integral dynamical models to the data to determine the best-fitting values for the BH mass MBH = (5.5 +/- 3.0) × 107Msolar (3? errors) and (M/L)K = (0.65 +/- 0.15) in solar units. These values are in excellent agreement with previous determinations from the gas kinematics, and in particular with our own published value, extracted from the same data. This provides one of the cleanest gas versus stars comparisons of MBH determination, due to the use of integral-field data for both dynamical tracers and due to a very well-resolved BH sphere of influence RBH ~ 0.70 arcsec. We derive an accurate profile of the orbital anisotropy, and carefully test its reliability using spherical Jeans models with radially varying anisotropy. We find an increase in the tangential anisotropy close to the BH, but the spatial extent of this effect seems restricted to the size of RBH instead of that of Rb ~ 3.9 arcsec of the core in the surface brightness profile, contrary to detailed predictions of current simulations of the binary BH scouring mechanism. More realistic simulations would be required to draw conclusions from this observation.

Cappellari, Michele; Neumayer, N.; Reunanen, J.; van der Werf, P. P.; de Zeeuw, P. T.; Rix, H.-W.

2009-04-01

360

Análise do STR-F13A01 e MPSs do mtDNA para fins de identificação humana: comparação de três métodos de extração de DNA de dentes submetidos ao calor  

Microsoft Academic Search

RESUMO Nos casos de carbonização humana, usualmente, há uma limitação do emprego dos remanescentes bio- lógicos para estudo. Nesses casos, têm-se usado por eleição dentes para análises forenses, já que sua cons- tituição anatômica proporciona proteção ao material genético. No presente estudo, avaliou-se a amplifica- ção por PCR do DNA obtido de dentes submetidos a calor (200ºC, 400ºC, 500ºC e

VANESSA ROSÁLIA REMUALDO; FABIO DAUMAS NUNES; MARIO HIROYUKI HIRATA

361

Fluorochrome and Fluorescent In Situ Hybridization to Monitor Bioaerosols in Swine Buildings  

Microsoft Academic Search

Total microbial cell concentration, viability, and culturability of bioaerosols in swine buildings were monitored by using epifluorescence microscopy with fluorochrome (EFM\\/FL) with four fluorescent dyes (AO, DAPI, PI, and YOPRO-1) and by using fluorescent in situ hybridization (FISH) with five oligonucleotide probes (fl-Univ, fl-EUB, cy-EUK, fl-PSMg, and fl-NotEUB) probes. Results from these two non-culture-based methods were then compared with those

Miao-Ching Chi; Chih-Shan Li

2005-01-01

362

Ensino de Sistemas de Informac ¸ ˜ ao para Cursos de Graduac ¸ ˜ ao em Computac ¸ ˜ ao: Uma Experiencia Integrada e Inovadora  

Microsoft Academic Search

Teaching Information Systems in Computer graduation course s uses techniques already being applyed in market for some years, b ut when the aim is to integrate new technologies to systems practice at real or ganization environ- ments, new integrated and inovative approaches need to be us ed. This article presents a teaching proposal for Information Systems based on an inovative

Ghedini Ralha; Jorge Henrique Cabral Fernandes

363

The structure of nuclei far from stability. [Dept. of Physics and Astronomy, Louisiana State Univ. , Baton Rouge, Louisiana  

SciTech Connect

Studies on nuclei near Z=82 contributed to the establishment of a new region of nuclear deformation and a new class of nuclear structure at closed shells. A important aspect of this work is the establishment of the connection between low-lying 0[sup +] states in even[endash]even nuclei and the occurrence of shape coexistence in the odd-mass neighbors (E0 transitions in [sup 185]Pt, shape coexistence in [sup 184]Pt and [sup 187]Au). A new type of picosecond lifetime measurement system capable of measuring the lifetime of states that decay only by internal conversion was developed and applied to the [sup 186,188]Tl decay to determine the lifetime of the 0[sub 2][sup +] and 2[sub 2][sup +] deformed states in [sup 186,188]Hg. A search for the population of superdeformed states in [sup 192]Hg by the radioactive decay of [sup 192]Tl was accomplished by using a prototype internal pair formation spectrometer.

Zganjar, E.F.

1993-01-01

364

Numerical solution of the incompressible Navier-Stokes equations. Ph.D. Thesis - Stanford Univ., Mar. 1989  

NASA Technical Reports Server (NTRS)

The current work is initiated in an effort to obtain an efficient, accurate, and robust algorithm for the numerical solution of the incompressible Navier-Stokes equations in two- and three-dimensional generalized curvilinear coordinates for both steady-state and time-dependent flow problems. This is accomplished with the use of the method of artificial compressibility and a high-order flux-difference splitting technique for the differencing of the convective terms. Time accuracy is obtained in the numerical solutions by subiterating the equations in psuedo-time for each physical time step. The system of equations is solved with a line-relaxation scheme which allows the use of very large pseudo-time steps leading to fast convergence for steady-state problems as well as for the subiterations of time-dependent problems. Numerous laminar test flow problems are computed and presented with a comparison against analytically known solutions or experimental results. These include the flow in a driven cavity, the flow over a backward-facing step, the steady and unsteady flow over a circular cylinder, flow over an oscillating plate, flow through a one-dimensional inviscid channel with oscillating back pressure, the steady-state flow through a square duct with a 90 degree bend, and the flow through an artificial heart configuration with moving boundaries. An adequate comparison with the analytical or experimental results is obtained in all cases. Numerical comparisons of the upwind differencing with central differencing plus artificial dissipation indicates that the upwind differencing provides a much more robust algorithm, which requires significantly less computing time. The time-dependent problems require on the order of 10 to 20 subiterations, indicating that the elliptical nature of the problem does require a substantial amount of computing effort.

Rogers, Stuart E.

1990-01-01

365

The Tribological Behavior of Polyphenyl Ether and Polyphenyl Thioether Aromatic Lubricants. Ph.D. Thesis - Kyushu Univ., Japan  

NASA Technical Reports Server (NTRS)

The tribological behavior of several polyphenyl ethers and polyphenyl thioethers is reported. Tribological areas covered include: surface tension and wettability measurements, boundary lubrication, ferrography, thermal and oxidative stability and chemiluminescence.

Jones, William R., Jr.

1987-01-01

366

Galactic background maps at 3.93 and 6.55 MHz. M.S. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

The Radio Astronomy Explorer Satellite (RAE-1), its hardware and its data processing are discussed. The data from the prime mapping antenna are discussed with emphasis on the problems involved in reducing the data. Particular attention is drawn to two problems - receiver instability and ground breakthrough - and their influence on the data. Galactic background maps of the nonthermal radiation at 3.93 and 6.55 MHz are produced. It is demonstrated that the positional uncertainity of the maps is about 20 deg. The maps at 3.93 and 6.55 MHz are compared to two ground based maps made at higher frequencies that are smoothed to the larger RAE antenna patterns.

Novaco, J. C.

1973-01-01

367

[Research in two-dimensional critical phenomena and conformal field theory]. [Rutgers, The State Univ. , New Brunswick, New Jersey  

SciTech Connect

A very theoretical description is given of research in two- dimensional critical phenomena and conformal field theory. Major progress is reported in the field of fluctuating two-dimensional surfaces. A discretized representation of fluctuating geometry is used where surfaces are represented by triangulations; continuum surfaces are recovered by taking the size of the triangles to zero. One of the central goals of the theory of critical phenomena is to find all possible universality classes of n-dimensional critical phenomena; this goal has been translated into the problem of clasifying all possible scale-invariant euclidean quantum field theories. (RWR)

Not Available

1990-01-01

368

A spatial model of wind shear and turbulence for flight simulation. Ph.D. Thesis - Colorado State Univ.  

NASA Technical Reports Server (NTRS)

A three dimensional model which combines measurements of wind shear in the real atmosphere with three dimensional Monte Carlo simulated turbulence was developed. The wind field over the body of an aircraft can be simulated and all aerodynamic loads and moments calculated.

Campbell, C. W.

1984-01-01

369

Fine Structure in 3C 120 and 3C 84. Ph.D. Thesis - Maryland Univ., 24 Aug. 1976  

NASA Technical Reports Server (NTRS)

Seven epochs of very long baseline radio interferometric observations of the Seyfert galaxies 3C 120 and 3C 84, at 3.8-cm wave length using stations at Westford, Massachusetts, Goldstone, California, Green Bank, West Virginia, and Onsala, Sweden, have been analyzed for source structure. An algorithm for reconstructing the brightness distribution of a spatially confined source from fringe amplitude and so called closure phase data has been developed and successfully applied to artificially generated test data and to data on the above mentioned sources. Over the two year time period of observation, 3C 120 was observed to consist of a double source showing apparent super relativistic expansion and separation velocities. The total flux changes comprising one outburst can be attributed to one of these components. 3C 84 showed much slower changes, evidently involving flux density changes in individual stationary components rather than relative motion.

Hutton, L. K.

1976-01-01

370

Full-Potential Modeling of Blade-Vortex Interactions. Degree awarded by George Washington Univ., Feb. 1987  

NASA Technical Reports Server (NTRS)

A study of the full-potential modeling of a blade-vortex interaction was made. A primary goal of this study was to investigate the effectiveness of the various methods of modeling the vortex. The model problem restricts the interaction to that of an infinite wing with an infinite line vortex moving parallel to its leading edge. This problem provides a convenient testing ground for the various methods of modeling the vortex while retaining the essential physics of the full three-dimensional interaction. A full-potential algorithm specifically tailored to solve the blade-vortex interaction (BVI) was developed to solve this problem. The basic algorithm was modified to include the effect of a vortex passing near the airfoil. Four different methods of modeling the vortex were used: (1) the angle-of-attack method, (2) the lifting-surface method, (3) the branch-cut method, and (4) the split-potential method. A side-by-side comparison of the four models was conducted. These comparisons included comparing generated velocity fields, a subcritical interaction, and a critical interaction. The subcritical and critical interactions are compared with experimentally generated results. The split-potential model was used to make a survey of some of the more critical parameters which affect the BVI.

Jones, Henry E.

1997-01-01

371

A modal aeroelastic analysis scheme for turbomachinery blading. M.S. Thesis - Case Western Reserve Univ. Final Report  

NASA Technical Reports Server (NTRS)

An aeroelastic analysis is developed which has general application to all types of axial-flow turbomachinery blades. The approach is based on linear modal analysis, where the blade's dynamic response is represented as a linear combination of contributions from each of its in-vacuum free vibrational modes. A compressible linearized unsteady potential theory is used to model the flow over the oscillating blades. The two-dimensional unsteady flow is evaluated along several stacked axisymmetric strips along the span of the airfoil. The unsteady pressures at the blade surface are integrated to result in the generalized force acting on the blade due to simple harmonic motions. The unsteady aerodynamic forces are coupled to the blade normal modes in the frequency domain using modal analysis. An iterative eigenvalue problem is solved to determine the stability of the blade when the unsteady aerodynamic forces are included in the analysis. The approach is demonstrated by applying it to a high-energy subsonic turbine blade from a rocket engine turbopump power turbine. The results indicate that this turbine could undergo flutter in an edgewise mode of vibration.

Smith, Todd E.

1991-01-01

372

Materials sciences research. Final report, 1 June 1975--30 September 1976. [Dept. of Electrical Engineering, Purdue Univ  

Microsoft Academic Search

This final report covers work in three areas. In the area of modulated microstructures hardened steel, the final result was a sample which had a strength of 270 ksi and a fracture toughness of ksi sq. root(in). These properties were obtained with a 50% soft layer and a special 0.28%C alloy (Ni, Co, C, Mo, V). In the area of

1976-01-01

373

Cooling of in-situ propellant rocket engines for Mars mission. M.S. Thesis - Cleveland State Univ.  

NASA Technical Reports Server (NTRS)

One propulsion option of a Mars ascent/descent vehicle is multiple high-pressure, pump-fed rocket engines using in-situ propellants, which have been derived from substances available on the Martian surface. The chosen in-situ propellant combination for this analysis is carbon monoxide as the fuel and oxygen as the oxidizer. Both could be extracted from carbon dioxide, which makes up 96 percent of the Martian atmosphere. A pump-fed rocket engine allows for higher chamber pressure than a pressure-fed engine, which in turn results in higher thrust and in higher heat flux in the combustion chamber. The heat flowing through the wall cannot be sufficiently dissipated by radiation cooling and, therefore, a regenerative coolant may be necessary to avoid melting the rocket engine. The two possible fluids for this coolant scheme, carbon monoxide and oxygen, are compared analytically. To determine their heat transfer capability, they are evaluated based upon their heat transfer and fluid flow characteristics.

Armstrong, Elizabeth S.

1991-01-01

374

[Reaction mechanism studies of heavy ion induced nuclear reactions]. [Dept. of Chemistry and Biochemistry, Univ. of Maryland, College Park, Maryland  

SciTech Connect

Completed work is summarized on the topics of excitation energy division in deep-inelastic reactions and the onset of multifragmentation in La-induced reactions at E/A = 45 MeV. Magnetic fields are being calculated for the PHOBOS detector system, a two-arm multiparticle spectrometer for studying low-transverse-momentum particles produced at the Relativistic Heavy Ion Collider. The Maryland Forward Array is being developed for detection of the reaction products from very peripheral collisions; it consists of two individual units of detectors: the annular silicon detector in front and the plastic phoswich detector at back.

Mignerey, A.C.

1993-02-01

375

Heat Transfer and Fluid Mechanics Institute, 33rd, California State Univ. , Sacramento, June 3, 4, 1993, Proceedings  

SciTech Connect

The present volume on heat transfer and fluid mechanics discusses vortex shedding and pressure oscillations in rockets and ramjets, chemically reactive turbulent flow mixing mechanisms, a computational study of atomization in a high-speed gas flow, and the development and verification of a computer model of cross-flow atomization. Attention is given to viscous liquid flow heating, a method of local corrections for high-speed viscous flows, an experimental study of the transient temperature distributions in concrete, and the thermal stability of two horizontal fluid layers with radiative heating from above. Topics addressed include the effect of molecular diffusion on the scalar field injet mixing, the effect of scattering on the total emittance from an isothermal gas-particle mixture, heat transfer to a bubble suspended in a liquid layer near a solid plate, and a finite analytic solution of Burger's equation using a node moving algorithm.

Reardon, F.H.

1993-01-01

376

Contributions on the Subject of Longitudinal Movements of Aircraft in Wind Shears. Ph.D. Thesis - Technischen Univ., 1983  

NASA Technical Reports Server (NTRS)

The effect of downburst-type wind shears on the longitudinal dynamic behavior of an unguided aircraft is simulated numerically on the basis of published meteorological data and the flight characteristics of an A300-B passenger jet. The nonlinear differential equations of the aircraft motion are linearized by conventional methods, and the wind effects are introduced via the linear derivatives of the wind components referred to the wind gradients to obtain simplified technical models of the longitudinal response to all possible types of constant-gradient wind shears during the first 20-60 sec. Graphs, maps, and diagrams are provided, and a number of accidents presumed to have involved wind shears are analyzed in detail.

Krauspe, P.

1985-01-01

377

Computational aspects of sensitivity calculations in linear transient structural analysis. Ph.D. Thesis - Virginia Polytechnic Inst. and State Univ.  

NASA Technical Reports Server (NTRS)

A study was performed focusing on the calculation of sensitivities of displacements, velocities, accelerations, and stresses in linear, structural, transient response problems. One significant goal of the study was to develop and evaluate sensitivity calculation techniques suitable for large-order finite element analyses. Accordingly, approximation vectors such as vibration mode shapes are used to reduce the dimensionality of the finite element model. Much of the research focused on the accuracy of both response quantities and sensitivities as a function of number of vectors used. Two types of sensitivity calculation techniques were developed and evaluated. The first type of technique is an overall finite difference method where the analysis is repeated for perturbed designs. The second type of technique is termed semi-analytical because it involves direct, analytical differentiation of the equations of motion with finite difference approximation of the coefficient matrices. To be computationally practical in large-order problems, the overall finite difference methods must use the approximation vectors from the original design in the analyses of the perturbed models. In several cases this fixed mode approach resulted in very poor approximations of the stress sensitivities. Almost all of the original modes were required for an accurate sensitivity and for small numbers of modes, the accuracy was extremely poor. To overcome this poor accuracy, two semi-analytical techniques were developed. The first technique accounts for the change in eigenvectors through approximate eigenvector derivatives. The second technique applies the mode acceleration method of transient analysis to the sensitivity calculations. Both result in accurate values of the stress sensitivities with a small number of modes and much lower computational costs than if the vibration modes were recalculated and then used in an overall finite difference method.

Greene, William H.

1990-01-01

378

Clearance flow-generated transverse forces at the rotors of thermal turbomachines. Ph.D. Thesis - Technische Univ., 1975  

NASA Technical Reports Server (NTRS)

Self-excited rotor whirl represents a serious hazard in the operation of turbomachines. The reported investigation has, therefore, the objective to measure the lateral forces acting on the rotor and to determine the characteristic pressure distribution in the rotor clearance area. A description is presented of an approach for calculating the leakage flow in the case of an eccentric rotor position on the basis of empirical loss coefficients. The results are reported of an experimental investigation with a turbine stage, taking into account a variation of the clearance characteristics. The pressure data measured are consistent with the theoretical considerations.

Urlichs, K.

1983-01-01

379

Research Related to Multi Degree of Freedom Magnetic Suspensions. Degree awarded by Old Dominion Univ. Aug. 1997  

NASA Technical Reports Server (NTRS)

This thesis covers the activities associated with (1) recommissioning of the 6-inch Magnetic Suspension and Balance System (MSBS) and (2) enhancing the Annular Suspension and Pointing System (ASPS). These activities continue the program of research in the multi degree of freedom magnetic suspension program at Old Dominion University. The 6-inch MSBS is a large gap magnetic suspension system used as a model support and balance system in wind tunnels. The first stage of recommissioning of the 6-inch MSBS for the 6-inch subsonic wind tunnel is performed. Experimental data and computational results for the magnetic field distribution of the MSBS are given and compared with the estimated magnetic field strength. The comparison indicates that the magnet system is still operating as designed. The Electromagnetic Position Sensor used in the 6-inch MSBS is analyzed before its find reinstatement. The ASPS is a small gap magnetic suspension system providing orientation, mechanical isolation and fine pointing of space payloads. The control system of the ASPS is improved by designing a new code to realize red time control over the system. The original Proportional-Derivative controller is upgraded to a Proportional-Integral-Derivative controller. This progress leads to a system which is more stable and robust with less noise. This new controller is generic and can be adapted to the 6-inch MSBS. Finally, future work on these two systems is proposed.

Britcher, Colin; Yang, Yan

1997-01-01

380

High Energy Particle Acceleration and Turbulent Magnetic Field Amplification in Shell Type Supernova Remnants. Degree awarded by Minnesota Univ.  

NASA Technical Reports Server (NTRS)

Thesis submitted to the faculty of the Graduate School of the University of Minnesota in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Part I discusses the spatial correlation between the x-ray and radio morphologies of Cas A, and in the process address: the effect of inhomogeneous absorption on the apparent x-ray morphology, the interaction between the SNR and a molecular cloud, and the rapid move toward equipartition between the magnetic and gas energy densities. Discussions of the x-ray./radio correlation continues in Chapter 5, where we present a new, deep, ROSAT HRI image of Cas A. Chapter 7 presents ASCA spectra, with non-thermal spectral fits for 13 of the youngest SNRs in the Galaxy.

Keohane, Jonathan Wilmore

1998-01-01

381

Personality Correlated of Success in Interviewing at the USUHS(Uniformed Services Univ. of Health Sciences) School of Medicine.  

National Technical Information Service (NTIS)

Interviewing is a widely used and heavily weighted selection tool for many occupational and educational programs. This is certainly the case for entrance to medical schools in the United States, with the vast majority requiring, or at least strongly encou...

R. K. Gifford D. G. Ebner

1976-01-01

382

Arbitrarily Curved and Twisted Space Beams. Ph.D. Thesis - Va. Polytech. Inst. and State Univ.; [Elastic Deformation, Stress Analysis  

NASA Technical Reports Server (NTRS)

A derivation of the equations which govern the deformation of an arbitrarily curved and twisted space beam is presented. These equations differ from those of the classical theory in that (1) extensional effects are included; (2) the strain-displacement relations are derived; and (3) the expressions for the stress resultants are developed from the strain displacement relations. It is shown that the torsional stress resultant obtained by the classical approach is basically incorrect except when the cross-section is circular. The governing equations are given in the form of first-order differential equations. A numerical algorithm is given for obtaining the natural vibration characteristics and example problems are presented.

Hunter, W. F.

1974-01-01

383

The effect of grain boundaries on the resistivity of polycrystalline silicon. Ph.D. Thesis - Va. Univ.  

NASA Technical Reports Server (NTRS)

The electrical resistivity of polycrystalline silicon films was investigated. The films were grown by the chemical vapor decomposition of silane on oxidized silicon wafers. The resistivity was found to be independent of dopant atom concentration in the lightly doped regions but was a strong function of dopant levels in the more heavily doped regions. A model, based on high dopant atom segregation in the grain boundaries, is proposed to explain the results.

Fripp, A. L., Jr.

1974-01-01

384

Creep-Rupture Data Analysis - Engineering Application of Regression Techniques. Ph.D. Thesis - North Carolina State Univ.  

NASA Technical Reports Server (NTRS)

The results are presented of investigations to apply regression techniques to the development of methodology for creep-rupture data analysis. Regression analysis techniques are applied to the explicit description of the creep behavior of materials for space shuttle thermal protection systems. A regression analysis technique is compared with five parametric methods for analyzing three simulated and twenty real data sets, and a computer program for the evaluation of creep-rupture data is presented.

Rummler, D. R.

1976-01-01

385

Stress concentration factors for circular, reinforced penetrations in pressurized cylindrical shells. Ph.D. Thesis - Virginia Univ.  

NASA Technical Reports Server (NTRS)

The effect on stresses in a cylindrical shell with a circular penetration subject to internal pressure was investigated in thin, shallow linearly, elastic cylindrical shells. Results provide numerical predictions of peak stress concentration factors around nonreinforced and reinforced penetrations in pressurized cylindrical shells. Analytical results were correlated with published formulas, as well as theoretical and experimental results. An accuracy study was made of the finite element program for each of the configurations considered important in pressure vessel technology. A formula is developed to predict the peak stress concentration factor for analysis and/or design in conjunction with the ASME Boiler and Pressure Vessel Code.

Ramsey, J. W., Jr.

1975-01-01

386

CRCHD - CRCHD Research - Research and Education Partnership between NC A&T and the Wake Forest Univ. CCC  

Cancer.gov

To achieve the first objective, the P20 will provide pilot funds for two collaborative research projects, one in prostate cancer chemopreventive agents and the other in glioblastoma cell mobility and resistance to therapeutics.

387

Transonic aerodynamics of dense gases. M.S. Thesis - Virginia Polytechnic Inst. and State Univ., Apr. 1990  

NASA Technical Reports Server (NTRS)

Transonic flow of dense gases for two-dimensional, steady-state, flow over a NACA 0012 airfoil was predicted analytically. The computer code used to model the dense gas behavior was a modified version of Jameson's FL052 airfoil code. The modifications to the code enabled modeling the dense gas behavior near the saturated vapor curve and critical pressure region where the fundamental derivative, Gamma, is negative. This negative Gamma region is of interest because the nonclassical gas behavior such as formation and propagation of expansion shocks, and the disintegration of inadmissible compression shocks may exist. The results indicated that dense gases with undisturbed thermodynamic states in the negative Gamma region show a significant reduction in the extent of the transonic regime as compared to that predicted by the perfect gas theory. The results support existing theories and predictions of the nonclassical, dense gas behavior from previous investigations.

Morren, Sybil Huang

1991-01-01

388

Methods in probability and statistical inference. Final report, June 15, 1975-June 30, 1979. [Dept. of Statistics, Univ. of Chicago  

SciTech Connect

This report describes the research activities of the Department of Statistics, University of Chicago, during the period June 15, 1975 to July 30, 1979. Nine research projects are briefly described on the following subjects: statistical computing and approximation techniques in statistics; numerical computation of first passage distributions; probabilities of large deviations; combining independent tests of significance; small-sample efficiencies of tests and estimates; improved procedures for simultaneous estimation and testing of many correlations; statistical computing and improved regression methods; comparison of several populations; and unbiasedness in multivariate statistics. A description of the statistical consultation activities of the Department that are of interest to DOE, in particular, the scientific interactions between the Department and the scientists at Argonne National Laboratories, is given. A list of publications issued during the term of the contract is included.

Wallace, D L; Perlman, M D

1980-06-01

389

Damage Mechanisms and Controlled Crack Propagation in a Hot Pressed Silicon Nitride Ceramic. Ph.D. Thesis - Northwestern Univ., 1993  

NASA Technical Reports Server (NTRS)

The subcritical growth of cracks from pre-existing flaws in ceramics can severely affect the structural reliability of a material. The ability to directly observe subcritical crack growth and rigorously analyze its influence on fracture behavior is important for an accurate assessment of material performance. A Mode I fracture specimen and loading method has been developed which permits the observation of stable, subcritical crack extension in monolithic and toughened ceramics. The test specimen and procedure has demonstrated its ability to generate and stably propagate sharp, through-thickness cracks in brittle high modulus materials. Crack growth for an aluminum oxide ceramic was observed to be continuously stable throughout testing. Conversely, the fracture behavior of a silicon nitride ceramic exhibited crack growth as a series of subcritical extensions which are interrupted by dynamic propagation. Dynamic initiation and arrest fracture resistance measurements for the silicon nitride averaged 67 and 48 J/sq m, respectively. The dynamic initiation event was observed to be sudden and explosive. Increments of subcritical crack growth contributed to a 40 percent increase in fracture resistance before dynamic initiation. Subcritical crack growth visibly marked the fracture surface with an increase in surface roughness. Increments of subcritical crack growth loosen ceramic material near the fracture surface and the fracture debris is easily removed by a replication technique. Fracture debris is viewed as evidence that both crack bridging and subsurface microcracking may be some of the mechanisms contributing to the increase in fracture resistance. A Statistical Fracture Mechanics model specifically developed to address subcritical crack growth and fracture reliability is used together with a damaged zone of material at the crack tip to model experimental results. A Monte Carlo simulation of the actual experiments was used to establish a set of modeling input parameters. It was demonstrated that a single critical parameter does not characterize the conditions required for dynamic initiation. Experimental measurements for critical crack lengths, and the energy release rates exhibit significant scatter. The resulting output of the model produces good agreement with both the average values and scatter of experimental measurements.

Calomino, Anthony Martin

1994-01-01

390

Progress report on research program in elementary particle theory, 1979-1980. [Univ. of Texas at Austin  

SciTech Connect

A qualitative description is given of research in the following areas: particle physics in relativistic astrophysics and cosmology; phenomenology of weak and electromagnetic interactions; strong interaction physics and quark-parton physics; quantum mechanics, quantum field theory, and fundamental problems; and groups, gauges, and grand unified theories. Reports on this work have already been published, or will be, when it is completed. (RWR)

Sudarshan, E.C.G.; Ne'eman, Y.

1980-01-01

391

Analysis and optimization of truncated scarf nozzles subject to external flow conditions. M.S. Thesis - Toledo Univ.  

NASA Technical Reports Server (NTRS)

Results of a calculation of an optimized truncated scarfed nozzle were compared. The truncated scarfed nozzle was designed for an exit Mach number of 6.0, i.e., the Mach number at the last nozzle characteristic is 6.0, with an external flow Mach number of 5.0. The nozzle was designed by the Rao method for optimum thrust nozzles modified for 2-D flow and truncated scarfed nozzle applications. This design was analyzed using a shock-fitting method for 2-D supersonic flows. Excellent agreement was achieved between the design and analysis. Truncation of the lower nozzle wall (cowl) revealed that there is an optimum length for truncating the cowl without degrading the nozzle performance. Truncation of the nozzle cowl past this optimal length should be analyzed in trade-off studies for thrust loss versus gross vehicle weight. Plots of the oblique shock wave equations were also identified which will allow computation of slip line angle, dynamic pressure coefficient, or ambient Mach number for various specific heat ratios.

Shyne, Rickey J.

1988-01-01

392

Experimental investigation of turbulent flow through a circular-to-rectangular transition duct. Ph.D. Thesis - Washington Univ.  

NASA Technical Reports Server (NTRS)

Steady, incompressible, turbulent, swirl-free flow through a circular-to-rectangular transition duck was studied experimentally. The cross-sectional area remains the same at the exit as at the inlet, but varies through the transition section to a maximum value approximately 15 percent above the inlet value. The cross-sectional geometry everywhere along the duct is defined by the equation of a superellipse. Mean and turbulence data were accumulated utilizing pressure and hot-wire instrumentation at five stations along the test section. Data are presented for operating bulk Reynolds numbers of 88,000 and 390,000. Measured quantities include total and static pressure, the three components of the mean velocity vector, and the six components of the Reynolds stress tensor. In addition to the transition duct measurements, a hot-wire technique which relies on the sequential use of single rotatable normal and slant-wire probes was proposed. The technique is applicable for measurement of the total mean velocity vector and the complete Reynolds stress tensor when the primary flow is arbitrarily skewed relative to a plane which lies normal to the probe axis of rotation.

Davis, David O.

1991-01-01

393

A fuzzy measure approach to motion frame analysis for scene detection. M.S. Thesis - Houston Univ.  

NASA Technical Reports Server (NTRS)

This paper addresses a solution to the problem of scene estimation of motion video data in the fuzzy set theoretic framework. Using fuzzy image feature extractors, a new algorithm is developed to compute the change of information in each of two successive frames to classify scenes. This classification process of raw input visual data can be used to establish structure for correlation. The algorithm attempts to fulfill the need for nonlinear, frame-accurate access to video data for applications such as video editing and visual document archival/retrieval systems in multimedia environments.

Leigh, Albert B.; Pal, Sankar K.

1992-01-01

394

Charge composition of high energy heavy primary cosmic ray nuclei. Ph.D. Thesis - Catholic Univ. of Am.  

NASA Technical Reports Server (NTRS)

A detailed study of the charge composition of primary cosmic radiation for about 5000 charged nuclei from neon to iron with energies greater than 1.16 GeV/nucleon is presented. Values are obtained after corrections were made for detector dependences, atmospheric attenuation, and solar modulation. New values of 38.5, 32.4, 23.7, and 16.8 g/sq cm for the attenuation mean free paths in air for the same charge groups are presented.

Price, R. D.

1974-01-01

395

UNIV 83. A Student's Work. Proceedings of the International University Congress (15th, Rome, Italy, March 26-April 4, 1983).  

ERIC Educational Resources Information Center

In this proceedings, attention is focused on career preparation and the relationship between general and specialized studies, as well as the link between theoretical knowledge and practical experience. The preparatory study for the congress was conducted in about 300 universities, primarily in Europe and America. Nearly 15,000 interviews were…

Cooperation in Education: International Quarterly of the Institute for University Cooperation, 1983

1983-01-01

396

Gamma-ray bursts; Proceedings of the Workshop, Univ. of Alabama, Huntsville, Oct. 16-18, 1991  

NASA Astrophysics Data System (ADS)

Recent developments in gamma-ray burst research are discussed with emphasis on new observations of gamma-ray bursts made by the Compton Gamma-Ray Observatory, Granat, Ginga, Pioneer Venus Orbiter, Prognoz, and Phobos. The papers are grouped under the following headings: general, historical, recent spacecraft observations; spatial and intensity distributions; galactic and extragalactic models; spectral observations; time profiles; and search for counterparts. Specific topics discussed include an upper limit on the luminosity of cosmological gamma-ray bursts; low-mass X-ray binaries and gamma-ray bursts; spectral evolution of gamma-ray bursts; ionization of gamma-ray-burst environments; and BATSE observations of bremsstrahlung from electron precipitation events.

Paciesas, William S.; Fishman, Gerald J.

397

The characteristics of a possible low altitude electron layer in the Martian atmosphere. M.S. Thesis - George Washington Univ.  

NASA Technical Reports Server (NTRS)

The apparent diurnal Martian surface pressure variation, as deduced from radio occultation experiments, is discussed and explained as possibly arising from the effect of a low altitude electron layer. Possible source and loss mechanisms for the low altitude electron layer are presented and discussed. Time-dependent differential equations describing the electron layer are derived and then integrated to investigate the electron distribution resulting from the several processes that might occur in the atmosphere. It is concluded that the source mechanism is the sublimation of alkali atoms from a permanent dust layer (a dust layer of 0.2 micron particles of density 9/cu cm is sufficient), and that the dominant loss process must involve CO2 clustering to the alkali atoms. Using these processes, an electron layer is developed which would explain the apparent diurnal surface pressure.

Wallio, H. A.

1973-01-01

398

An Exponential Finite Difference Technique for Solving Partial Differential Equations. M.S. Thesis - Toledo Univ., Ohio  

NASA Technical Reports Server (NTRS)

An exponential finite difference algorithm, as first presented by Bhattacharya for one-dimensianal steady-state, heat conduction in Cartesian coordinates, has been extended. The finite difference algorithm developed was used to solve the diffusion equation in one-dimensional cylindrical coordinates and applied to two- and three-dimensional problems in Cartesian coordinates. The method was also used to solve nonlinear partial differential equations in one (Burger's equation) and two (Boundary Layer equations) dimensional Cartesian coordinates. Predicted results were compared to exact solutions where available, or to results obtained by other numerical methods. It was found that the exponential finite difference method produced results that were more accurate than those obtained by other numerical methods, especially during the initial transient portion of the solution. Other applications made using the exponential finite difference technique included unsteady one-dimensional heat transfer with temperature varying thermal conductivity and the development of the temperature field in a laminar Couette flow.

Handschuh, Robert F.

1987-01-01

399

Assessment of Potential Aerodynamic Benefits from Spanwise Blowing at the Wing Tip. Ph.D. Thesis - George Washington Univ.  

NASA Technical Reports Server (NTRS)

A comprehensive set of experimental and analytical investigations have been conducted to assess the potential aerodynamic benefits from spanwise blowing at the tip of a moderate aspect ratio, swept wing. An analytical model has been developed to simulate a jet exhausting from the wing tip. An experimental study of a subsonic jet exhausting from the wing tip was conducted to investigate the effect of spanwise blowing from the tip on the aerodynamic characteristics of a moderate aspect ratio, swept wing. Wing force and moment data and surface pressure data were measured at Mach numbers up to 0.72. Results indicate that small amounts of blowing from small jets increase the lift curve slope a small amount, but have no effect on drag. Larger amounts of blowing from longer jets blowing increases lift near the tip and reduce drag at low Mach numbers. These benefits decrease with increasing Mach number, and vanish at Mach 0.5. A Navier-Stokes solver with modified boundary conditions at the tip was used to extrapolate the results to a Mach number of 0.72. With current technology and conventional wing shapes, spanwise blowing at the wing tip does not appear to be a practical means of reducing drag of moderate aspect ratio wings at high subsonic Mach numbers.

Mineck, Raymond Edward

1992-01-01

400

System Identification of Damped Truss-Like Space Structures. Ph.D. Thesis - Cleveland State Univ., Mar. 1994  

NASA Technical Reports Server (NTRS)

A spacecraft payload flown on a launch vehicle experiences dynamic loads. The dynamic loads are caused by various phenomena ranging from the start-up of the launch vehicle engine to wind gusts. A spacecraft payload should be designed to meet launch vehicle dynamic loads. One of the major steps taken towards determining the dynamic loads is to correlate the finite element model of the spacecraft with the test results of a modal survey test. A test-verified finite element model of the spacecraft should possess the same spatial properties (stiffness, mass, and damping) and modal properties (frequencies and mode shapes) as the test hardware representing the spacecraft. The test-verified and correlated finite element model of the spacecraft is then coupled with the finite element model of the launch vehicle for analysis of loads and stress. Modal survey testing, verification of a finite element model, and modification of the finite element model to match the modal survey test results can easily be accomplished if the spacecraft structure is simple. However, this is rarely the case. A simple structure here is defined as a structure where the influence of nonlinearity between force and displacement (uncertainty in a test, for example, with errors in input and output), and the influence of damping (structural, coulomb, and viscous) are not pronounced. The objective of this study is to develop system identification and correlation methods with the focus on the structural systems that possess nonproportional damping. Two approaches to correct the nonproportional damping matrix of a truss structure were studied, and have been implemented on truss-like structures such as the National Aeronautics and Space Administration's space station truss. The results of this study showed nearly 100 percent improvement of the correlated eigensystem over the analytical eigensystem. The first method showed excellent results with up to three modes used in the system identification process. The second method could handle more modes, but required more computer usage time, and the results were less accurate than those of the first method.

Armand, Sasan

1995-01-01

401

Procedures for Computing Transonic Flows for Control of Adaptive Wind Tunnels. Ph.D. Thesis - Technische Univ., Berlin, Mar. 1986  

NASA Technical Reports Server (NTRS)

Numerical methods are developed for control of three dimensional adaptive test sections. The physical properties of the design problem occurring in the external field computation are analyzed, and a design procedure suited for solution of the problem is worked out. To do this, the desired wall shape is determined by stepwise modification of an initial contour. The necessary changes in geometry are determined with the aid of a panel procedure, or, with incident flow near the sonic range, with a transonic small perturbation (TSP) procedure. The designed wall shape, together with the wall deflections set during the tunnel run, are the input to a newly derived one-step formula which immediately yields the adapted wall contour. This is particularly important since the classical iterative adaptation scheme is shown to converge poorly for 3D flows. Experimental results obtained in the adaptive test section with eight flexible walls are presented to demonstrate the potential of the procedure. Finally, a method is described to minimize wall interference in 3D flows by adapting only the top and bottom wind tunnel walls.

Rebstock, Rainer

1987-01-01

402

Studies in tilt rotor VTOL aircraft aeroelasticity, volume 2. Ph.D. Thesis - Case Western Reserve Univ.  

NASA Technical Reports Server (NTRS)

Two methods for natural mode vibration analysis are discussed. The first consists of a direct approach based on a finite element representation of the complete structure as an entity. The mass and stiffness matrices for the complete structure are assembled by properly combining the mass and stiffness matrices of the individual elements into which the structure has been divided. The second approach is that of component mode synthesis. This method is based on the concept of synthesizing the natural modes of the complete structure from modes of conveniently difined substructures, or components, into which the structure has been partitioned. In this way the expedient of reducing the system degrees of freedom, and thus the size of the eigenvalue problem, can be introduced by partial modal synthesis.

Kvaternik, R. G.

1973-01-01

403

Study of potential aerodynamic benefits from spanwise blowing at wingtip. Ph.D. Thesis - George Washington Univ., 1992  

NASA Technical Reports Server (NTRS)

Comprehensive experimental and analytical studies have been conducted to assess the potential aerodynamic benefits from spanwise blowing at the tip of a moderate-aspect-ratio swept wing. Previous studies on low-aspect-ratio wings indicated that blowing from the wingtip can diffuse the tip vortex and displace it outward. The diffused and displaced vortex will induce a smaller downwash at the wing, and consequently the wing will have increased lift and decreased induced drag at a given angle of attack. Results from the present investigation indicated that blowing from jets with a short chord had little effect on lift or drag, but blowing from jets with a longer chord increased lift near the tip and reduced drag at low Mach numbers. A Navier-Stokes solver with modified boundary conditions at the tip was used to extrapolate the results to a Mach number of 0.72. Calculations indicated that lift and drag increase with increasing jet momentum coefficient. Because the momentum of the jet is typically greater than the reduction in the wing drag and the increase in the wing lift due to spanwise blowing is small, spanwise blowing at the wingtip does not appear to be a practical means of improving the aerodynamic efficiency of moderate-aspectratio swept wings at high subsonic Mach numbers.

Mineck, Raymond E.

1995-01-01

404

Evaluation of equilibrium turbulence for a hypersonic boundary layer at nonadiabatic wall conditions. M.S. Thesis - Old Dominion Univ.  

NASA Technical Reports Server (NTRS)

This paper presents an experimental study to characterize the naturally developing compressible turbulent boundary layer produced along a flat plate measuring 9.7 feet long in the NASA Langley 8-Foot High Temperature Tunnel and to determine the test conditions necessary to achieve equilibrium turbulence. The measurements consist of pitot pressure, static pressure, and total temperature distributions in the boundary layer. In addition, surface measurements consisting of heat transfer and pressure distributions were obtained. The tests were conducted at a nominal free-stream Mach number of 6.5, total temperatures of 2700 and 3300 R, and angles of attack of 5 and 13 degrees. The corresponding nominal boundary-layer edge Mach numbers were 6.2 and 5.0. The nominal ratios of adiabatic wall temperature to cold wall temperature were 4.4 and 5.4 and the momentum thickness Reynolds numbers at the boundary layer probe locations ranged from 400 to 7800. The results of this study indicate that momentum thickness Reynolds numbers of at least 4000 are required to obtain an equilibrium turbulent boundary layer in the Langley 8-Foot High Temperature Tunnel. This evaluation is based primarily on the behavior of shape factors inferred from the boundary-layer measurements.

Albertson, Cindy W.

1989-01-01

405

On the Age of Cosmic Rays as Derived from the Abundance of Be-10. Ph.D. Thesis - Maryland Univ.  

NASA Technical Reports Server (NTRS)

The isotopic composition of cosmic ray Be, B, C, and N was studied using a new range versus total light technique. Special emphasis was placed on the Be isotopes and in particular, on the radioactive isotope Be-10 due to its mean lifetime against decay. The experiment consisted of a thin trigger scintillator, an acrylic plastic Cerenkov detector and a spark chamber, followed by a totally active stack of 14 scintillation detectors. This stack of scintillators made possible the measurement of range, and also permitted the removal of interacting events by continuously monitoring their identities along their trajectories. The experiment was carried by balloon to atmospheric depths ranging from 3.5 to 5.0 g sq cm residual atmosphere for a total exposure time of 23 hr. Results indicate the survival of ( 55 + or -21) % of the Be-10 in the arriving cosmic rays; the data were interpreted using the leaky box model of cosmic ray propagation.

Hagen, F. A.

1976-01-01

406

Triangulation Error Analysis for the Barium Ion Cloud Experiment. M.S. Thesis - North Carolina State Univ.  

NASA Technical Reports Server (NTRS)

The triangulation method developed specifically for the Barium Ion Cloud Project is discussed. Expression for the four displacement errors, the three slope errors, and the curvature error in the triangulation solution due to a probable error in the lines-of-sight from the observation stations to points on the cloud are derived. The triangulation method is then used to determine the effect of the following on these different errors in the solution: the number and location of the stations, the observation duration, east-west cloud drift, the number of input data points, and the addition of extra cameras to one of the stations. The pointing displacement errors, and the pointing slope errors are compared. The displacement errors in the solution due to a probable error in the position of a moving station plus the weighting factors for the data from the moving station are also determined.

Long, S. A. T.

1973-01-01

407

Stigmatically focusing partial pressure analyzer with dual chamber ion source. Ph.D. Thesis - Technical Univ. of Munich, 1971  

NASA Technical Reports Server (NTRS)

The partial pressure analyzer developed has a high absolute sensitivity and high resolution. Interaction effects, as they occur in conventional partial pressure analyzers between the heating filament for the emission of electrons and the residual gas, are suppressed by removing the heating filament from the measurement area. The electron beam is generated in an auxiliary vacuum compartment, and passes subsequently through an aperture into the ionization compartment. The probability is small, therefore, that the presence of substances produced at the heating filament by chemical reactions and thermal decompositions will have disturbing effects. The high sensitivity and resolution of the instrument are obtained with the aid of an electron path configuration of unconventional characteristics.

Rasskopf, Klaus F.

1987-01-01

408

Experimental study of void formation during aluminum solidification in reduced gravity. Ph.D. Thesis - Toledo Univ.  

NASA Technical Reports Server (NTRS)

Void formation due to volumetric shrinkage and liquid/vapor reorientation during aluminum solidification was observed in real time by using a radiographic viewing system in normal and reduced gravity. An end-chill directional solidification furnace with water quench was designed and constructed to solidify aluminum samples during the approximately 16 sec of reduced gravity (+/-0.02g) achieved by flying an aircraft through a parabolic trajectory. In the first series of tests the aluminum was contained in a vacuum sealed, pyrolytic boron nitride crucible. An ullage space was present during each test. Void formation was recorded for two cases: a nonwetting system, and a wetting system where wetting occurred between the aluminum and the crucible lid. The void formation in the nonwetting case was similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible. In the wetting case during reduced gravity surface tension caused two voids to form in the top corners of the crucible, but during normal gravity only one large void formed across the top. In the second series of tests the aluminum was contained in a pyrolytic boron nitride crucible that was placed in a stainless steel container and sealed in an environment of argon plus 4 percent hydrogen. An ullage space was present during each test. Void formation was recorded for two cases: a nonwetting system, and a wetting system where wetting occurred between the aluminum and one side wall and the lid. The void for nation in the nonwetting case was similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible, although the meniscus became more convex in reduced gravity. In the wetting case the aluminum did not climb up the corners in 1g, and one large symmetric void resulted at the top when the aluminum had solidified. In the wetting case during reduced gravity the molten aluminum was drawn up the wetted wall and partially across the lid by a capillary underpressure; however, on the nonwetting wall the aluminum moved down. One void resulted along the nonwetting side of the container continuing to the top on the same side.

Chiaramonte, Francis Paul, III

1993-01-01

409

Finite Element Analysis of Active and Sensory Thermopiezoelectric Composite Materials. Degree awarded by Northwestern Univ., Dec. 2000  

NASA Technical Reports Server (NTRS)

Analytical formulations are developed to account for the coupled mechanical, electrical, and thermal response of piezoelectric composite materials. The coupled response is captured at the material level through the thermopiezoelectric constitutive equations and leads to the inherent capability to model both the sensory and active responses of piezoelectric materials. A layerwise laminate theory is incorporated to provide more accurate analysis of the displacements, strains, stresses, electric fields, and thermal fields through-the-thickness. Thermal effects which arise from coefficient of thermal expansion mismatch, pyroelectric effects, and temperature dependent material properties are explicitly accounted for in the formulation. Corresponding finite element formulations are developed for piezoelectric beam, plate, and shell elements to provide a more generalized capability for the analysis of arbitrary piezoelectric composite structures. The accuracy of the current formulation is verified with comparisons from published experimental data and other analytical models. Additional numerical studies are also conducted to demonstrate additional capabilities of the formulation to represent the sensory and active behaviors. A future plan of experimental studies is provided to characterize the high temperature dynamic response of piezoelectric composite materials.

Lee, Ho-Jun

2001-01-01

410

Abort performance for a winged-body single-stage to orbit vehicle. M.S. Thesis - George Washington Univ.  

NASA Technical Reports Server (NTRS)

Optimal control theory is employed to determine the performance of abort to orbit (ATO) and return to launch site (RTLS) maneuvers for a single-stage to orbit vehicle. The vehicle configuration examined is a seven engine, winged-body vehicle, that lifts-off vertically and lands horizontally. The abort maneuvers occur as the vehicle ascends to orbit and are initiated when the vehicle suffers an engine failure. The optimal control problems are numerically solved in discretized form via a nonlinear programming (NLP) algorithm. A description highlighting the attributes of this NLP method is provided. ATO maneuver results show that the vehicle is capable of ascending to orbit with a single engine failure at lift-off. Two engine out ATO maneuvers are not possible from the launch pad, but are possible after launch when the thrust to weight ratio becomes sufficiently large. Results show that single engine out RTLS maneuvers can be made for up to 180 seconds after lift-off and that there are scenarios for which RTLS maneuvers should be performed instead of ATP maneuvers.

Lyon, Jeffery A.

1995-01-01